JP6713151B2 - Force sensor - Google Patents

Description

The present invention relates to a force sensor, and more particularly to a sensor suitable for detecting a force in each coordinate axis direction and a moment about each coordinate axis in a three-dimensional Cartesian coordinate system.

Various types of force sensors are used to control the operation of robots and industrial machines. Also, a small force sensor is incorporated as a man-machine interface of an input device of electronic equipment. The force sensor used for such an application has a structure that is as simple as possible for the purpose of downsizing and cost reduction, and is capable of independently detecting forces on each coordinate axis in a three-dimensional space. Is required.

Currently, generally used multi-axis force sensors are of a type that detects a specific directional component of a force acting on a mechanical structure as a displacement generated in a specific portion, and a type that is generated in the specific portion. It is classified as a type that is detected as mechanical strain. The representative of the former displacement detection type is a capacitive element type force sensor, in which a capacitive element is composed of a pair of electrodes, and the displacement generated in one electrode by the applied force is measured by the capacitive element. It is detected based on the capacitance value. For example, Patent Document 1 (the English version thereof is Patent Document 2) and Patent Document 3 (the English version thereof are Patent Document 4) below disclose this capacitive multi-axis force sensor.

On the other hand, the representative of the latter mechanical strain detection type is a strain gauge type force sensor, which detects mechanical strain caused by an applied force as a change in electrical resistance of a strain gauge or the like. is there. For example, the following Patent Document 5 (English version of which is Patent Document 6) discloses this strain gauge type multi-axis force sensor.

However, in each of the multi-axis force sensors disclosed in the above-mentioned patent documents, the mechanical structure is inevitably thick, and it is difficult to reduce the thickness of the entire device. On the other hand, in the fields of robots, industrial machines, input devices for electronic devices, and the like, the appearance of thinner force sensors is desired. Therefore, Patent Document 7 proposes a force sensor in which the shape of an annular member is deformed by the action of force and the displacement of each part caused by this deformation is detected by a capacitive element. The force sensor (referred to as a prior application force sensor in the present application) disclosed in Patent Document 7 has a structure suitable for simplifying the structure and reducing the thickness.

JP 2004-325367 A U.S. Pat. No. 7,219,561 JP 2004-354049 A US Pat. No. 6,915,709 JP-A-8-122178 US Pat. No. 5,490,427 International Publication No. WO2013/014803

However, in the above-described prior application force sensor, it is necessary to dispose the capacitive element at various places in order to detect various deformation modes of the annular member, so that the electrode configuration of the capacitive element must be complicated. I don't get. Moreover, since the relative position of the pair of electrodes forming the capacitive element is a significant factor affecting the detection accuracy, a large work load is required to adjust the position of each electrode. In particular, when a plurality of capacitive elements are arranged with symmetry and difference detection is performed using them, the counter electrodes should be parallel for each individual capacitive element and the electrode spacing for the multiple capacitive elements should be Must be adjusted so that are equal to each other. Therefore, in commercial use, there is a problem that production efficiency is lowered and cost is increased.

Therefore, it is an object of the present invention to provide a force sensor having a simple structure, and by improving the degree of freedom in arranging the detecting elements, high productivity can be realized.

(1) A first aspect of the present invention is a force sensor for detecting a force or a moment about at least one axis among a force in each coordinate axis direction and a moment around each coordinate axis in an XYZ three-dimensional orthogonal coordinate system,
A force-receiving body that receives a force or moment to be detected,
A detection ring having a ring structure extending along a predetermined basic ring road, and a detection part located at a detection point defined on the basic ring road, and a connecting part located on both sides of this detection part, and a detection ring,
A support for supporting the detection ring,
A connecting member that connects the force receiving body to a position of a predetermined point of action of the detection ring;
A fixing member for fixing the position of a predetermined fixed point of the detection ring to the support,
A detection element that detects elastic deformation generated in the detection unit,
A detection circuit that outputs an electric signal indicating a force or a moment acting on the other of the force receiving body and the supporting body based on the detection result of the detection element when a load is applied to one of the force receiving body and the support;
Is provided
The action point and the fixed point are arranged at different positions of the connecting portion,
The detection unit has a structure in which, when a force is applied between the action point and the fixed point, at least a part of the detection unit elastically deforms based on the applied force.

(2) A second aspect of the present invention is the force sensor according to the above-mentioned first aspect,
The detection element is constituted by a capacitive element having a displacement electrode fixed at a predetermined position of the detection unit, and a fixed electrode fixed at a position facing the displacement electrode of the support or the force receiving body,
The displacement electrode is arranged at a position where displacement is caused with respect to the fixed electrode based on the elastic deformation generated in the detection unit,
The detection circuit outputs an electric signal indicating the applied force or moment based on the change in the capacitance value of the capacitive element.

(3) A third aspect of the present invention is the force sensor according to the above second aspect,
Taking the XY plane as the horizontal plane and the Z axis as the axis that goes vertically upward,
The detection ring has an annular structure extending along a basic annular path located in the XY plane with the Z axis as the central axis,
The support is composed of a support substrate arranged below the detection ring at a predetermined interval,
The displacement electrode is fixed to the lower surface of the detection unit, and the fixed electrode is fixed to the upper surface of the support substrate.

(4) A fourth aspect of the present invention is the force sensor according to the above-mentioned third aspect,
The detection unit includes a first deformation unit that elastically deforms due to the action of a force or a moment that is a detection target, a second deformation unit that elastically deforms due to the action of a force or a moment that is a detection target, and a first deformation. And a displacement portion that is displaced by elastic deformation of the second deformable portion,
The outer end of the first deformable portion is connected to the adjacent connecting portion, the inner end of the first deformable portion is connected to the displacing portion, and the outer end of the second deformable portion is connected to the adjacent connecting portion. Connected, the inner end of the second deformable portion is connected to the displacement portion,
The displacement electrode is fixed at a position of the displacement portion facing the support substrate.

(5) A fifth aspect of the present invention is the force sensor according to the above-mentioned fourth aspect,
A plurality of n (n≧2) detection points are defined on the basic ring road, the detection portions are located at the respective detection points, and the detection ring connects the n detection portions and the n connection portions with each other. It is constructed by alternately arranging along the basic ring road.

(6) A sixth aspect of the present invention is the force sensor according to the fifth aspect described above,
An even number n (n≧2) of detection points are defined on the basic ring road, and the detection portions are located at the respective detection points, and the detection ring connects the n detection portions and the n connection portions with each other. It is constructed by alternately arranging along the basic ring road.

(7) A seventh aspect of the present invention is the force sensor according to the sixth aspect described above,
When the numbers are given to the even-numbered n connecting parts in order along the basic ring road, the action points are arranged in the odd-numbered connecting parts and the fixed points are arranged in the even-numbered connecting parts. It is the one.

(8) An eighth aspect of the present invention is the force sensor according to the seventh aspect described above,
By setting n=2, by arranging the first connecting portion, the first detecting portion, the second connecting portion, and the second detecting portion in this order along the basic annular path, the detecting ring is arranged. Is configured such that the point of action is located at the first connecting portion and the fixed point is located at the second connecting portion.

(9) A ninth aspect of the present invention is the force sensor according to the seventh aspect described above,
By setting n=4, the first connecting portion, the first detecting portion, the second connecting portion, the second detecting portion, the third connecting portion, and the third detecting portion are arranged along the basic annular path. The detection ring is configured by arranging the first section, the fourth connection section, and the fourth detection section in this order, and the first action point is arranged on the first connection section and the first fixed point. Is arranged in the second connecting part, the second action point is arranged in the third connecting part, the second fixing point is arranged in the fourth connecting part,
A connection member connects a first operating point of the detection ring to the force receiving body, and a second connecting member connects a second operating point of the detection ring to the force receiving body. Has and
The fixing member includes a first fixing member that fixes the position of the first fixing point of the detection ring to the support substrate, and a second fixing member that fixes the position of the second fixing point of the detection ring to the support substrate. I have it.

(10) A tenth aspect of the present invention is the force sensor according to the ninth aspect described above,
The first point of action is located on the positive X axis, the second point of action is located on the negative X axis, the first fixed point is located on the positive Y axis, and the second fixed point. Are arranged on the negative Y-axis.

(11) An eleventh aspect of the present invention is the force sensor according to the tenth aspect described above,
On the XY plane, the V axis is defined as a coordinate axis obtained by rotating the X axis counterclockwise by 45° about the origin O, and the W axis is defined as a coordinate axis rotated by 45° counterclockwise about the origin O. , The first detection point is on the positive V axis, the second detection point is on the positive W axis, the third detection point is on the negative V axis, and the fourth detection point is on the negative V axis. It is arranged on the W axis.

(12) A twelfth aspect of the present invention is the force sensor according to the eleventh aspect described above,
Each of the detectors is formed with a capacitive element whose increase and decrease in capacitance value is reversed when a compressive stress acts along the basic annular path and when a tensile stress acts.
The capacitance value of the first capacitive element having the displacement electrode fixed to the first detection portion located at the first detection point is C1, and the capacitance value is fixed to the second detection portion located at the second detection point. The capacitance value of the second capacitance element having the displacement electrode is C2, and the capacitance value of the third capacitance element having the displacement electrode fixed to the third detection portion located at the third detection point is C3, when the electrostatic capacitance value of the fourth capacitive element having the displacement electrode fixed to the fourth detection portion located at the fourth detection point is C4,
The detection circuit
Fz=-(C1+C2+C3+C4)
Mx=-C1-C2+C3+C4
My=+C1-C2-C3+C4
Mz=+C1-C2+C3-C4
By performing an operation based on the following equation, an electric force indicating a force Fz acting in the Z-axis direction, a moment Mx acting about the X-axis, a moment My acting about the Y-axis, and a moment Mz acting about the Z-axis. It is designed to output a signal.

(13) A thirteenth aspect of the present invention is the force sensor according to the seventh aspect described above,
By setting n=8, the first connecting portion, the first detecting portion, the second connecting portion, the second detecting portion, the third connecting portion, and the third detecting portion are arranged along the basic circular path. Section, fourth connecting section, fourth detecting section, fifth connecting section, fifth detecting section, sixth connecting section, sixth detecting section, seventh connecting section, seventh detecting section, The detection ring is configured by arranging the eighth connection portion and the eighth detection portion in this order,
The first point of action is located on the first link, the first fixed point is located on the second link, the second point of action is located on the third link, and the second point is fixed. Are arranged on the fourth connecting part, the third operating point is arranged on the fifth connecting part, the third fixed point is arranged on the sixth connecting part, and the fourth operating point is on the seventh connecting part. The fourth fixing point is arranged on the eighth connecting portion,
A connection member connects a first operating point of the detection ring to the force receiving body, and a second connecting member connects a second operating point of the detection ring to the force receiving body. A third connecting member that connects the position of the third action point of the detection ring to the force receiving body, and a fourth connecting member that connects the position of the fourth action point of the detection ring to the force receiving body, Have
A first fixing member for fixing the position of the first fixing point of the detection ring to the support substrate; and a second fixing member for fixing the position of the second fixing point of the detection ring to the support substrate. A third fixing member for fixing the position of the third fixing point of the detection ring to the support substrate, and a fourth fixing member for fixing the position of the fourth fixing point of the detection ring to the support substrate. It was done.

(14) A fourteenth aspect of the present invention is the force sensor according to the thirteenth aspect described above,
On the XY plane, the V axis is defined as a coordinate axis obtained by rotating the X axis counterclockwise by 45° about the origin O, and the W axis is defined as a coordinate axis rotated by 45° counterclockwise about the origin O. If you define
The first point of action is on the positive X axis, the second point of action is on the positive Y axis, the third point of action is on the negative X axis, and the fourth point of action is on the negative Y axis. Are arranged on the positive V-axis, the second fixed point on the positive W-axis, the third fixed point on the negative V-axis, and the fourth fixed point on the negative W-axis. It was done like this.

(15) A fifteenth aspect of the present invention is the force sensor according to the above-mentioned fourteenth aspect,
On the XY plane, when the azimuth vector Vec(θ) that makes an angle θ counterclockwise with respect to the positive direction of the X-axis from the origin O is defined, the ith vector (1≦i≦8) The detection point is arranged at the intersection of the azimuth vector Vec(π/8+(i-1)·π/4) and the basic ring road.

(16) A sixteenth aspect of the present invention is the force sensor according to the fifteenth aspect described above,
Each of the detectors is formed with a capacitive element whose increase and decrease in capacitance value is reversed when a compressive stress acts along the basic annular path and when a tensile stress acts.
When the capacitance value of the i-th capacitive element having the displacement electrode fixed to the i-th detection portion located at the i-th detection point is C1i,
The detection circuit
Regarding the force Fx acting in the X-axis direction,
Fx=-C11+C12-C13+C14+C15-C16+C17-C18
Alternatively, Fx=-C11+C12+C17-C18
Alternatively, Fx=+C12-C13-C16+C17
The arithmetic expression,
Regarding the force Fy acting in the Y-axis direction,
Fy=+C11-C12-C13+C14-C15+C16+C17-C18
Alternatively, Fy=+C11-C12-C13+C14
Or Fy=-C15+C16+C17-C18
The arithmetic expression,
Regarding the force Fz acting in the Z-axis direction,
Fz=-(C11+C12+C13+C14+C15+C16+C17+C18)
Alternatively, Fz=-(C11+C14+C15+C18)
Alternatively, Fz=-(C12+C13+C16+C17)
Arithmetic expression,
Regarding the moment Mx acting around the X axis,
Mx=-C11-C12-C13-C14+C15+C16+C17+C18
Alternatively, Mx=-C11-C12+C17+C18
Alternatively, Mx=-C13-C14+C15+C16
Arithmetic expression,
Regarding the moment My acting around the Y axis,
My=+C11+C12-C13-C14-C15-C16+C17+C18
Alternatively, My=+C11+C12-C13-C14
Alternatively, My=-C15-C16+C17+C18
Arithmetic expression,
Regarding the moment Mz acting around the Z axis,
Mz=+C11-C12+C13-C14+C15-C16+C17-C18
Alternatively, Mz=+C11-C12+C15-C16
Alternatively, Mz=+C13-C14+C17-C18
Alternatively, Mz=+C11-C14+C15-C18
Arithmetic expression,
The electric signals indicating the force Fx, the force Fy, the force Fz, the moment Mx, the moment My, and the moment Mz are output by performing the calculation based on

(17) A seventeenth aspect of the present invention is the force sensor according to the sixth aspect described above,
When numbers are sequentially assigned to even-numbered n connecting parts along the basic ring road, the action points and the fixed points are basically odd-numbered connecting parts, and the action points and the fixed points are basically the same. It is arranged so as to alternate along the circular road.

(18) An eighteenth aspect of the present invention is the force sensor according to the seventeenth aspect described above,
By setting n=8, the first connecting portion, the first detecting portion, the second connecting portion, the second detecting portion, the third connecting portion, and the third detecting portion are arranged along the basic circular path. Section, fourth connecting section, fourth detecting section, fifth connecting section, fifth detecting section, sixth connecting section, sixth detecting section, seventh connecting section, seventh detecting section, The detection ring is configured by arranging the eighth connection portion and the eighth detection portion in this order,
The first fixed point is arranged on the first connecting part, the first operating point is arranged on the third connecting part, the second fixed point is arranged on the fifth connecting part, and the second operating point is arranged. Is placed in the seventh connection,
A connection member connects a first operating point of the detection ring to the force receiving body, and a second connecting member connects a second operating point of the detection ring to the force receiving body. And have,
A first fixing member that fixes the position of the first fixing point of the detection ring to the support substrate; and a second fixing member that fixes the position of the second fixing point of the detection ring to the support substrate; To have.

(19) A nineteenth aspect of the present invention is the force sensor according to the eighteenth aspect described above,
The first fixed point is located on the positive X axis, the second fixed point is located on the negative X axis, the first working point is located on the positive Y axis, and the second working point is Are arranged on the negative Y-axis.

(20) A twentieth aspect of the present invention is the force sensor according to the nineteenth aspect described above,
The detection ring is a square annular structure that is arranged on the XY plane with the origin O as the center, and extends in a direction parallel to the Y-axis, a first side intersecting the positive X-axis, and a direction parallel to the X-axis. A second side that intersects the positive Y-axis and a third side that intersects the negative X-axis in the direction parallel to the Y-axis, and a third Y-axis that extends in the direction parallel to the X-axis And a fourth side to
The first detection point is arranged at a position having the positive Y coordinate of the first side, the second detection point is arranged at a position having the positive X coordinate of the second side, and the third detection point is arranged. The point is arranged at a position having a negative X coordinate on the second side, the fourth detection point is arranged at a position having a positive Y coordinate on the third side, and the fifth detection point is The third detection point is arranged at a position having a negative Y coordinate on the third side, the sixth detection point is arranged at a position having a negative X coordinate on the fourth side, and the seventh detection point is arranged on a fourth side. It is arranged at a position having a positive X coordinate, and the eighth detection point is arranged at a position having a negative Y coordinate on the first side.

(21) A twenty-first aspect of the present invention is the force sensor according to the twentieth aspect described above,
Each of the detectors is formed with a capacitive element whose increase and decrease in capacitance value is reversed when a compressive stress acts along the basic annular path and when a tensile stress acts.
When the capacitance value of the i-th capacitive element having the displacement electrode fixed to the i-th detection portion located at the i-th detection point is C1i,
The detection circuit
Regarding the force Fx acting in the X-axis direction,
Fx=+C12-C13-C16+C17
The arithmetic expression,
Regarding the force Fy acting in the Y-axis direction,
Fy=-C11-C14+C15+C18
The arithmetic expression,
Regarding the force Fz acting in the Z-axis direction,
Fz=-(C11+C12+C13+C14+C15+C16+C17+C18)
Alternatively, Fz=-(C11+C13+C15+C17)
Alternatively, Fz=-(C12+C14+C16+C18)
The arithmetic expression,
Regarding the moment Mx acting around the X axis,
Mx=-C11-C12-C13-C14+C15+C16+C17+C18
Alternatively, Mx=-C12-C13+C16+C17
The arithmetic expression,
Regarding the moment My acting around the Y axis,
My=+C11+C12-C13-C14-C15-C16+C17+C18
Alternatively, My=+C11-C14-C15+C18
The arithmetic expression,
Regarding the moment Mz acting around the Z axis,
Mz=-C11-C12+C13+C14-C15-C16+C17+C18
Alternatively, Mz=-C11+C13-C15+C17
Alternatively, Mz=-C12+C14-C16+C18
The arithmetic expression,
The electric signals indicating the force Fx, the force Fy, the force Fz, the moment Mx, the moment My, and the moment Mz are output by performing the calculation based on.

(22) A twenty-second aspect of the present invention provides the force sensor according to the nineteenth aspect described above,
The detection ring is a circular annular structure arranged on the XY plane with the origin O as the center,
On the XY plane, when the azimuth vector Vec(θ) that makes an angle θ counterclockwise with respect to the positive direction of the X-axis from the origin O is defined, the ith vector (1≦i≦8) The detection point is arranged at the intersection of the azimuth vector Vec(π/8+(i-1)·π/4) and the basic ring road.

(23) A twenty-third aspect of the present invention provides the force sensor according to the fifth to twenty-second aspects described above,
Regarding a force or moment about a specific axis to be detected, some of the plurality of n detection units behave as a detection unit of the first attribute, and another part behaves as a detection unit of the second attribute,
The first-attribute displacement unit, which constitutes the first-attribute detection unit, is displaced in a direction approaching the support substrate when the positive component about the specific axis acts, and the negative component about the specific axis acts. Is displaced in the direction away from the support substrate,
The second attribute displacement section, which constitutes the second attribute detection section, is displaced in a direction away from the support substrate when a positive component about the specific axis acts, and a negative component about the specific axis acts. When it does, it is displaced in the direction of approaching the support substrate
The first attribute displacement electrode fixed to the first attribute displacement portion and the first attribute fixed electrode fixed to a position of the support substrate facing the first attribute displacement electrode constitute a first attribute capacitive element,
The second attribute displacement electrode fixed to the second attribute displacement portion and the second attribute fixed electrode fixed to a position of the support substrate facing the second attribute displacement electrode constitute a second attribute capacitive element,
The detection circuit outputs an electrical signal corresponding to the difference between the electrostatic capacitance value of the first attribute capacitive element and the electrostatic capacitance value of the second attribute capacitive element for the specific axis of the force or moment to be detected. The electric signal indicating the component of is output.

(24) A twenty-fourth aspect of the present invention is the force sensor according to the fourth to twenty-third aspects described above,
The detection ring is obtained by partially performing a material removal process on an annular member obtained by forming a through opening in the central portion of a plate-shaped member arranged with the Z axis as the central axis. The detection part is constituted by the part subjected to the material removal processing.

(25) A twenty-fifth aspect of the present invention provides the force sensor according to the fourth to twenty-fourth aspects described above,
A detection unit having a first deformable portion, a second deformable portion, and a displacing portion is arranged between one connecting portion end portion and the other connecting portion end portion,
The first deformable portion is formed of a flexible first plate-shaped piece, the second deformable portion is formed of a flexible second plate-shaped piece, and the displacement portion is formed of the third deformable portion. It is composed of plate pieces of
The outer end of the first plate-shaped piece is connected to one end of the connecting portion, the inner end of the first plate-shaped piece is connected to one end of the third plate-shaped piece, and the second plate-shaped piece is connected. The outer end of is connected to the end of the other connecting portion, and the inner end of the second plate-shaped piece is connected to the other end of the third plate-shaped piece.

(26) A twenty-sixth aspect of the present invention is the force sensor according to the twenty-fifth aspect described above,
In the state where no force or moment is applied, the opposing surface of the third plate-shaped piece and the opposing surface of the supporting substrate are kept parallel to each other.

(27) A twenty-seventh aspect of the present invention is the force sensor according to the twenty-sixth aspect,
When a normal line orthogonal to the XY plane is set at the position of the detection point, the first plate-shaped piece and the second plate-shaped piece forming the detection unit located at the detection point are inclined with respect to the normal line. In addition, the inclination direction of the first plate-shaped piece and the inclination direction of the second plate-shaped piece are opposite to each other.

(28) A twenty-eighth aspect of the present invention is the force sensor according to the third to twenty-seventh aspects described above,
When a connection reference line parallel to the Z-axis is defined by passing through the action point or a movement point obtained by moving the action point along a line connecting the origin O and the action point of the coordinate system, An auxiliary connecting member for connecting the lower surface of the detection ring or the force receiving body and the upper surface of the support substrate is further provided along the vicinity.

(29) A twenty-ninth aspect of the present invention is the force sensor according to the twenty-eighth aspect described above,
As the auxiliary connecting member, a member that is more likely to elastically deform when a force acts in a direction orthogonal to the connection reference line than when a force acts in a direction along the connection reference line is used. It is a thing.

(30) A thirtieth aspect of the present invention is the force sensor according to the twenty-eighth or twenty-ninth aspect described above,
The detection ring or the force receiving body is connected to the auxiliary connection member, or the support substrate is connected to the auxiliary connection member, or both of these connection parts are constituted by diaphragm portions, and the diaphragm portion based on the action of force or moment. The auxiliary connection member is tilted with respect to the connection reference line by the deformation of.

(31) A thirty-first aspect of the present invention is the force sensor according to any of the above-described second to thirtieth aspects,
One of the fixed electrode and the displacement electrode is arranged so that the effective facing area of the pair of electrodes forming the capacitive element does not change even when the displacement electrode moves in parallel with the fixed electrode as a result of the force or moment. The area of is set to be larger than the other area.

(32) A thirty-second aspect of the present invention is the force sensor according to the above-described second to thirty-first aspects,
The detection ring, support, and force receiver are made of a conductive material, the displacement electrode is formed on the surface of the detection ring via an insulating layer, and the fixed electrode is insulated on the surface of the support or force receiver. It is formed so as to interpose layers.

(33) A thirty-third aspect of the present invention is the force sensor according to the above-mentioned second to thirty-second aspects,
The detection ring, the support, and the force receiving body are made of a conductive material, and the displacement electrode is formed by a partial area of the surface of the detection ring, or the displacement electrode is formed by a part of the surface of the support or the force receiving body. A fixed electrode is constituted by the region.

(34) A thirty-fourth aspect of the present invention is the force sensor according to the above-mentioned first aspect,
The detection element is composed of a strain gauge fixed at a position that causes elastic deformation of the detection unit,
The detection circuit outputs an electric signal indicating the applied force or moment based on the change in the electric resistance of the strain gauge.

(35) A thirty-fifth aspect of the present invention is the force sensor according to the above-mentioned thirty-fourth aspect,
The detection unit has a plate-shaped deforming portion that elastically deforms by the action of a force or moment to be detected, and the plate-shaped deforming portion is arranged so that its plate surface is inclined with respect to the basic annular path. It is the one.

(36) A thirty-sixth aspect of the present invention is the force sensor according to the thirty-fifth aspect described above,
The detection elements are constituted by strain gauges arranged on both surfaces in the vicinity of the connection end of the plate-shaped deformable portion to the connecting portion.

(37) A thirty-seventh aspect of the present invention is the force sensor according to the above-mentioned thirty-sixth aspect,
The detection elements are a first strain gauge and a second strain gauge, which are respectively disposed on the front surface and the back surface near the first connecting end with respect to the connecting portion, and the front side near the second connecting end with respect to the connecting portion. A third strain gauge and a fourth strain gauge, which are respectively disposed on the surface and the back surface,
The detection circuit detects a bridge voltage of a bridge circuit having the first strain gauge and the fourth strain gauge as the first opposite sides and the second strain gauge and the third strain gauge as the second opposite sides. It was done like this.

(38) A thirty-eighth aspect of the present invention is the force sensor according to the above-described first to nineteenth and thirty-fourth to thirty-seventh aspects,
The detection ring is an annular structure whose basic annular path is a circle arranged in the XY plane with the Z axis as the central axis,
The support is a circular plate-shaped structure or annular structure arranged in the Z-axis negative region with the Z-axis as the central axis,
The force receiving body is a circular plate-shaped structure or annular structure arranged in the Z-axis positive region with the Z-axis as the central axis, or a circular plate-shaped structure arranged in the XY plane with the Z-axis as the central axis, or It is a ring structure.

(39) A thirty-ninth aspect of the present invention is the force sensor according to the above-described first to nineteenth and thirty-fourth to thirty-seventh aspects,
The detection ring is an annular structure whose basic annular path is a square arranged on the XY plane with the Z axis as the central axis,
The support is a square plate-like structure or an annular structure arranged in the Z-axis negative region with the Z-axis as the central axis,
The force receiving body is a square plate-shaped structure or an annular structure arranged in the Z-axis positive region with the Z-axis as the central axis, or a square plate-shaped structure arranged in the XY plane with the Z-axis as the central axis, or It is a ring structure.

(40) A fortieth aspect of the present invention is the force sensor according to the above-mentioned first to thirty-ninth aspects,
The force receiving body is an annular structure capable of accommodating the detection ring inside, and the force receiving body is arranged outside the detection ring.

(41) A forty-first aspect of the present invention is the force sensor according to the above-mentioned first to thirty-ninth aspects,
The detection ring is an annular structure capable of accommodating the force receiving body inside, and the force receiving body is arranged inside the detection ring.

(42) A forty-second aspect of the present invention is the force sensor according to the above-mentioned first to thirty-ninth aspects,
When the XY plane is a horizontal plane and the Z axis is an axis that extends vertically upward, the detection ring is arranged on the XY plane, the support body is arranged below the detection ring at a predetermined interval, and the force receiving body is the detection ring. Are arranged at a predetermined interval above the.

In the force sensor according to the present invention, the applied force or moment is detected based on the deformation mode of the detection ring having the annular structure. This detection ring has a detection part that causes elastic deformation and connecting parts located on both sides of this detection part. When a force or moment to be detected acts, the detection ring concentrates elastic deformation on the detection part. Will occur. Here, the mode of elastic deformation occurring in the detection unit can be freely set by devising the shape and structure of the detection unit. Therefore, although the structure is simple, it is possible to provide a force sensor that can improve the degree of freedom in arranging the detection elements and realize high production efficiency.

When electrically detecting the displacement based on the elastic deformation of the detection unit, a capacitive element can be used as the detection element. In this case, the arrangement of the capacitive elements can be freely set by devising the shape and structure of the detection unit. Specifically, since the position and orientation of the surface on which the displacement electrode on the detection ring side is formed can be freely set, it is possible to design effectively in order to improve production efficiency. Further, when a force in a specific coordinate axis direction or a moment about a specific coordinate axis is applied, it is possible to design a part of the detection unit to be displaced in a specific direction. A force sensor that efficiently detects an arbitrary direction component can be designed.

Further, in the case of electrically detecting the stress strain based on the elastic deformation of the detecting portion, a strain gauge can be adopted as the detecting element. Also in this case, the strain gauge can be arranged freely by devising the shape and structure of the detection unit, so that an effective design can be achieved in order to improve the production efficiency. Therefore, even when the strain gauge is used as the detection element, it is possible to design a force sensor that efficiently detects an arbitrary directional component of the force or moment to be detected.

It is a top view (upper figure) and a side view (lower figure) of the basic structure part of the prior application force sensor. FIG. 2 is a horizontal cross-sectional view (upper view) taken along the XY plane and a vertical cross-sectional view (lower view) taken along the XZ plane of the basic structure portion shown in FIG. 1. FIG. 2 is a top view (upper view) of the support substrate 300 and the fixing members 510 and 520 of the basic structure shown in FIG. 1, and a vertical cross-sectional view (lower view) obtained by cutting the basic structure along the YZ plane. A transverse cross-sectional view (upper figure) and a vertical cross-sectional view (lower figure) in the XY plane showing a deformed state when a force +Fx in the positive direction of the X-axis is applied to the force receiving body 100 of the basic structure shown in FIG. Figure). It is a longitudinal cross-sectional view in the XZ plane which shows a deformed state when the force +Fz in the Z-axis positive direction acts on the force receiver 100 of the basic structure portion shown in FIG. It is a longitudinal cross-sectional view in the XZ plane which shows a deformed state when the moment +My about the Y-axis is applied to the force receiving body 100 of the basic structure shown in FIG. FIG. 3 is a transverse cross-sectional view in the XY plane showing a deformed state when a moment +Mz about the Z axis is applied to the force receiving body 100 of the basic structure portion shown in FIG. 1. 2A and 2B are a top view (upper view) and a side view (lower view) showing an embodiment in which a fixed auxiliary body 350 for displacement detection is added to the basic structure portion shown in FIG. 1. FIG. 9 is a horizontal cross-sectional view (upper diagram) taken along the XY plane and a vertical cross-sectional view (lower diagram) taken along the VZ plane of the basic structure portion shown in FIG. 8. It is a top view which shows the distance measurement location in the basic structure part shown in FIG. 11 is a table showing changes in the distances d1 to d8 when a force in each coordinate axis direction and a moment around each coordinate axis act on the basic structure shown in FIG. 10. A force sensor formed by adding a capacitive element to the basic structure shown in FIG. 9 is a cross-sectional view taken along the XY plane (upper diagram) and a vertical cross-sectional view cut along the VZ plane (lower diagram). is there. FIG. 3 is a perspective view (FIG. (a)), a side view (FIG. (b)) and a bottom view (FIG. (c)) of a detection ring 600 used in the force sensor according to the first embodiment of the present invention. It is a top view which shows the area|region distribution of the detection ring 600 shown in FIG. 13 (mesh-like hatching is for showing the area|region of detection parts D1-D4, and does not show a cross section). FIG. 14 is a plan view showing a basic loop road B defined on the XY plane and points defined on the basic loop road B in the detection ring 600 shown in FIG. 13. FIG. 2 is a top view (upper diagram) of a basic structure portion of the force sensor according to the first embodiment of the present invention and a side cross-sectional view (lower diagram) cut along the XZ plane. FIG. 14 is a partial cross-sectional view showing a detailed structure of detectors D1 to D4 (represented by a symbol D) of the detector ring 600 shown in FIG. 13. FIG. 14 is a partial cross-sectional view showing a detailed structure in which an electrode is provided on a predetermined portion of a detection substrate D 1 to D 4 (representatively denoted by reference symbol D) of the detection ring 600 shown in FIG. 13 and a supporting substrate 300 facing the detection portion. It is a figure which shows the principle which maintains the effective area of a capacitive element constant, even when the relative position of the displacement electrode with respect to a fixed electrode changes. FIG. 16 shows the fluctuation amount (degree of increase or decrease) of the capacitance value of each capacitive element when a force in each axial direction or a moment around each axis acts on the force receiving body 100 in the first embodiment shown in FIG. It's a table. It is a table obtained by approximately replacing the (-) and (+) columns in the table shown in FIG. 20 with zero. It is a figure which shows the calculation formula which calculates the 4-axis component of the force Fz which acted on the force receiving body 100 in 1st Embodiment shown in FIG. 16, and the moment Mx, My, Mz based on the table shown in FIG. FIG. 23 is a circuit diagram showing an example of a detection circuit that outputs an electrical signal indicating four-axis components of force Fz and moments Mx, My, Mz based on the arithmetic expression shown in FIG. 22. It is a bottom view of the detection ring 700 used for the force sensor which concerns on the 2nd Embodiment of this invention. FIG. 25 is a top view showing a region distribution of the detection ring 700 shown in FIG. 24 (mesh-like hatching is for showing regions of the detection parts D11 to D18, and is not a cross section). FIG. 25 is a plan view showing a basic loop road B defined at positions on the XY plane of the detection ring 700 shown in FIG. 24 and points defined on the basic loop road B. It is a top view of the basic structure part of the force sensor which concerns on the 2nd Embodiment of this invention. FIG. 27 shows a variation amount (degree of increase or decrease) of the capacitance value of each capacitive element when a force in each axial direction or a moment around each axis acts on the force receiving body 100 in the second embodiment shown in FIG. It's a table. Based on the table shown in FIG. 28, the formulas for calculating the six-axis components of the forces Fx, Fy, Fz acting on the force receiving body 100 and the moments Mx, My, Mz in the second embodiment shown in FIG. 27 will be shown. It is a figure. FIG. 30 is a diagram showing a variation of the arithmetic expression shown in FIG. 29. It is a bottom view (upper figure) of a basic structure part of a force sensor concerning a 3rd embodiment of the present invention, and a sectional side view (lower figure) which cut this in the XZ plane. FIG. 31 shows the amount of change (the degree of increase or decrease) in the capacitance value of each capacitance element when a force in each axial direction or a moment around each axis acts on the force receiving body 100 in the third embodiment shown in FIG. It's a table. FIG. 32 is a partial side cross-sectional view showing a modified example relating to the mounting portion of the auxiliary connection member 532 in the third embodiment shown in FIG. When a force in each axial direction or a moment about each axis acts on the force receiving body 100 of the embodiment according to the combination of the second embodiment shown in FIG. 24 and the third embodiment shown in FIG. 6 is a table showing the amount of change (degree of increase or decrease) in the capacitance value of the capacitive element. It is a top view of square-shaped detection ring 700S used for a force sensor concerning a 4th embodiment of the present invention. FIG. 36 is a top view showing a region distribution of the detection ring 700S shown in FIG. 35 (mesh-shaped hatching is for showing regions of the detection parts D11S to D18S, and is not a cross section). FIG. 36 is a plan view showing a basic loop road BS defined at a position on the XY plane of the detection ring 700S shown in FIG. 35 and points defined on the basic loop road BS. FIG. 35 is a table showing the variation amount (degree of increase or decrease) of the capacitance value of each capacitive element when a force in each axial direction or a moment around each axis acts on the force receiving body in the fourth embodiment shown in FIG. 35. Is. FIG. 38 is a diagram showing an arithmetic expression for calculating six-axis components of forces Fx, Fy, Fz and moments Mx, My, Mz acting on the force receiving body in the fourth embodiment shown in FIG. 35 based on the table shown in FIG. 38. Is. FIG. 40 is a diagram showing a variation of the arithmetic expression shown in FIG. 39. It is a top view of the basic structure part of the force sensor which concerns on the 5th Embodiment of this invention. FIG. 9 is a top view (upper diagram) of a basic structure portion of a force sensor according to a sixth embodiment of the present invention and a side cross-sectional view (lower diagram) taken by cutting it along the XZ plane. FIG. 16 is a top view (upper diagram) of a basic structure portion of a force sensor according to a seventh embodiment of the present invention and a side cross-sectional view (lower diagram) cut along the XZ plane. It is a fragmentary sectional view showing the variation of the structure of the detection part in the present invention. Instead of the detection ring 600 in the first embodiment shown in FIG. 16, a top view (upper diagram) of a basic structure part of a force sensor according to a modification using a detection ring 800 in which the direction of the detection part is changed, and It is a sectional side view (lower figure) taken along the XZ plane. FIG. 45 is a partial cross-sectional view showing a mode of elastic deformation of the plate-shaped deforming portion 80 constituting the detecting portion DD shown in FIG. 44(c). 44(c) is a side view (FIG. (a)) and a top view (FIG. (b)) showing an example in which a strain gauge is used as a detection element for detecting elastic deformation generated in the detection unit DD shown in FIG. 44(c). It is a circuit diagram which shows the bridge circuit which outputs an electric signal based on the detection result of 4 sets of strain gauges shown in FIG.

Hereinafter, the present invention will be described based on illustrated embodiments. The present invention is an improvement of the prior application force sensor disclosed in Patent Document 7 (International Publication No. WO2013/014803). Therefore, for convenience of description, first, the prior application force sensor will be described in the following §1 and §2, and the features of the present invention will be described in §3 and the following.

<<<<§1. Features of the basic structure part of the prior application force sensor >>>
FIG. 1 is a top view (upper view) and a side view (lower view) of a basic structure portion of a prior application force sensor. In the top view, the X axis is arranged on the right side of the figure and the Y axis is arranged on the upper side of the figure, and the front direction perpendicular to the plane of the drawing is the Z axis direction. On the other hand, in the side view, the X axis is arranged on the right side of the figure and the Z axis is arranged on the upper side of the figure, and the depth direction perpendicular to the paper surface is the Y axis direction. As shown in the figure, this basic structural unit is composed of the force receiving body 100, the detection ring 200, the support substrate 300, the connecting members 410 and 420, and the fixing members 510 and 520.

The force receiving body 100 is a circular flat plate-shaped (washer-shaped) ring arranged on the XY plane such that the Z axis is the central axis, and both the outer peripheral surface and the inner peripheral surface form a cylindrical surface. The role of the force receiving body 100 is to receive the action of a force or moment to be detected and transmit this to the detection ring 200.

On the other hand, like the force receiving body 100, the detection ring 200 is a circular flat plate-shaped (washer-shaped) ring arranged on the XY plane such that the Z axis serves as the central axis, and has both an outer peripheral surface and an inner peripheral surface. Construct a cylindrical surface. In the case of the example shown here, the detection ring 200 is arranged inside the force receiving body 100. That is, the force receiving body 100 is the outer ring arranged on the XY plane, and the detection ring 200 is the inner ring arranged on the XY plane. Here, the feature of the detection ring 200 is that elastic deformation occurs due to the action of a force or moment to be detected.

The connection members 410 and 420 are members for connecting the force receiver 100 and the detection ring 200. In the illustrated example, the connecting member 410 connects the inner peripheral surface of the force receiving body 100 and the outer peripheral surface of the detection ring 200 at a position along the X-axis positive area, and the connecting member 420 is the X-axis negative area. The inner peripheral surface of the force receiving body 100 and the outer peripheral surface of the detection ring 200 are connected at a position along the line. Therefore, a gap H1 is secured between the force receiving body 100 and the detection ring 200 as shown in the figure, and a gap H2 is secured inside the detection ring 200 as shown in the diagram.

As is clear from the side view shown in the lower part of FIG. 1, in this example, the force receiving body 100 and the detection ring 200 have the same thickness (dimension in the Z-axis direction). Is completely hidden inside the force receiving body 100. The thickness of both rings does not necessarily have to be the same, but it is preferable that both rings have the same thickness in order to realize a thin sensor (a sensor whose dimension in the Z-axis direction is as small as possible).

The support substrate 300 is a disk-shaped substrate having a diameter equal to the outer diameter of the force receiving body 100, has an upper surface parallel to the XY plane, and is arranged below the force receiving body 100 and the detection ring 200 at a predetermined interval. It The fixing members 510 and 520 are members for fixing the detection ring 200 to the support substrate 300. In the side view, the fixing member 510 does not appear hidden behind the fixing member 520, but the fixing members 510 and 520 play a role of connecting the lower surface of the detection ring 200 and the upper surface of the support substrate 300. As shown by the broken lines in the top view, the fixing members 510 and 520 are arranged at positions along the Y axis.

FIG. 2 is a horizontal cross-sectional view (upper view) taken along the XY plane and a vertical cross-sectional view (lower view) taken along the XZ plane of the basic structure shown in FIG. The origin O of the XYZ three-dimensional Cartesian coordinate system is shown at the center of the cross-sectional view taken along the XY plane. In FIG. 2, the state in which the detection ring 200 is connected to the force receiving body 100 via the connection members 410 and 420 arranged along the X axis at two left and right positions is clearly shown.

FIG. 3 is a top view (upper view) of the support substrate 300 and the fixing members 510 and 520 of the basic structure shown in FIG. 1, and a vertical cross-sectional view (lower view) of the basic structure taken along the YZ plane. Is. The top view of FIG. 3 corresponds to a state in which the top view of FIG. 1 is rotated 90° counterclockwise, and the Y axis is taken to the left. Further, in the top view of FIG. 3, the position of the detection ring 200 is shown by a broken line. On the other hand, in the vertical cross-sectional view of FIG. 3, a state in which the detection ring 200 is fixed above the support substrate 300 by the fixing members 510 and 520 is clearly shown.

As will be described later, when forces in various directions act on the force receiving body 100 in a state where the support substrate 300 is fixed, the detection ring 200 is deformed in a mode according to the applied force. The prior application force sensor detects the applied force by electrically detecting this deformation mode. Therefore, the easiness of elastic deformation of the detection ring 200 is a parameter that influences the detection sensitivity of the sensor. If the detection ring 200 that is easily elastically deformed is used, it is possible to realize a sensor with high sensitivity that can detect a small force, but the maximum detectable force is suppressed. On the contrary, if the detection ring 200 which is not easily elastically deformed is used, the maximum value of the force that can be detected can be increased, but the sensitivity is lowered, so that it becomes impossible to detect a minute force.

The easiness of elastic deformation of the detection ring 200 depends on the thickness in the Z-axis direction and the thickness in the radial direction (the smaller the thickness, the easier the elastic deformation), and further depends on the material thereof. Therefore, in practice, it is necessary to select the size and material of each part of the detection ring 200 according to the application of the force sensor. As will be described later, the detection ring used in the present invention is improved in this respect, and the degree of freedom in design can be further improved in accordance with industrial demand.

On the other hand, the force receiving body 100 and the support substrate 300 do not have to be members that cause elastic deformation in principle of detecting force. Rather, in order for the applied force to contribute 100% to the deformation of the detection ring 200, it is preferable that the force receiving body 100 and the support substrate 300 are completely rigid bodies. In the illustrated example, the reason why the ring-shaped structure having the void H1 at the center is used as the force receiving body 100 is not to facilitate elastic deformation but to accommodate the detection ring 200 inside. If the ring-shaped force receiving body 100 is arranged outside the detection ring 200 as in the illustrated example, the thickness of the basic structure portion can be reduced, and a thinner force sensor can be realized.

Practically, as the material of the force receiver 100, the detection ring 200, and the support substrate 300, if an insulating material is used, it is sufficient to use a synthetic resin such as plastic, and if a conductive material is used, It is sufficient to use a metal such as stainless steel or aluminum. Of course, an insulating material and a conductive material may be used in combination.

Next, in the state where the support substrate 300 is fixed, when the force in each coordinate axis direction and the moment about each coordinate axis act on the force receiving body 100, what kind of phenomenon occurs in this basic structure part will be considered. Try.

As described above, the force receiving body 100 and the support substrate 300 are preferably essentially rigid bodies so that the applied force contributes 100% to the deformation of the detection ring 200. However, in reality, when the basic structure portion is made of resin or metal, the force receiving body 100 and the support substrate 300 do not become perfect rigid bodies, and it can be said strictly that force and moment are applied to the force receiving body 100. In this case, the force receiving body 100 and the support substrate 300 are also slightly elastically deformed. However, if the elastic deformation generated in the force receiving body 100 or the support substrate 300 is a slight elastic deformation as compared with the elastic deformation generated in the detection ring 200, it can be ignored, and it can be considered as a substantially rigid body. Therefore, in the present application, the force receiving body 100 and the support substrate 300 are rigid bodies, and the elastic deformation due to the force or the moment occurs only in the detection ring 200.

First, let us consider what kind of change occurs in this basic structure when a force in the X-axis direction acts on the force receiver 100 with the support substrate 300 fixed. FIG. 4 is a horizontal cross-sectional view (upper view) in the XY plane and a vertical cross-section in the XZ plane showing a deformed state when the force +Fx in the positive direction of the X-axis is applied to the force receiving body 100 of the basic structure shown in FIG. It is a figure (lower figure). The support substrate 300 is fixed and therefore immovable, but the force receiving body 100 moves to the right in the figure by the force +Fx in the positive direction of the X axis. As a result, the detection ring 200 deforms as shown. The broken line shown in the figure indicates the position of each ring before movement or deformation.

Here, for convenience of explanation of this modification, two fixed points P1 and P2 (indicated by black circles) and two action points Q1 and Q2 (indicated by white circles) will be considered. The fixed points P1 and P2 are points defined on the Y-axis, and correspond to the positions of the fixed members 510 and 520 shown in FIG. That is, the detection ring 200 is fixed to the support substrate 300 by the fixing members 510 and 520 at the positions of the fixing points P1 and P2. On the other hand, the action points Q1 and Q2 are points defined on the X axis, and the detection ring 200 is connected to the force receiving body 100 by the connecting members 410 and 420 at the positions of the action points Q1 and Q2. ..

Thus, in the prior application force sensor, the action point is the position where the connecting member is connected and the fixed point is the position where the fixing member is connected. The important point is that the action point and the fixed point are arranged at different positions. In the case of the example shown in FIG. 4, the fixed points P1 and P2 and the action points Q1 and Q2 are arranged at different positions on the XY plane. This is because the detection ring 200 is not elastically deformed when the action point and the fixed point occupy the same position.

Now, when the force +Fx in the positive direction of the X-axis acts on the force receiving body 100, as shown in FIG. 4, the action points Q1 and Q2 (white circles) of the detection ring 200 receive a force to the right in the figure. Will join. However, since the positions of the fixed points P1 and P2 (black circles) of the detection ring 200 are fixed, the flexible detection ring 200 is deformed from the reference circular state to the distorted state as illustrated. (Note that the diagram showing the deformed state in the present application is a diagram that is somewhat deformed in order to emphasize the deformed state, and does not necessarily show an accurate deformed mode). Specifically, as shown in the figure, between points P1-Q1 and between points P2-Q1, tensile forces act on both ends of the quadrant of the detection ring 200, and the quadrant contracts inward, resulting in points P1-Q2. Between the points and between points P2 and Q2, the pressing force acts on both ends of the quadrant of the detection ring 200, and the quadrant bulges outward.

When a force −Fx in the negative direction of the X axis acts on the force receiver 100, a phenomenon opposite to that in FIG. 4 occurs. Further, when the force +Fy in the positive direction of the Y axis and the force −Fy in the negative direction of the Y axis act on the force receiver 100, a phenomenon occurs in which the deformed state in the upper part of FIG. 4 is rotated by 90°.

Next, let us consider what kind of change occurs in this basic structure when a force in the Z-axis direction acts on the force receiver 100 with the support substrate 300 fixed. FIG. 5 is a vertical cross-sectional view in the XZ plane showing a deformed state when a force +Fz in the Z-axis positive direction acts on the force receiving body 100 of the basic structure shown in FIG. The support substrate 300 is fixed and therefore immovable, but the force receiving body 100 moves upward in the figure by the force +Fz in the Z-axis positive direction. As a result, the detection ring 200 deforms as shown. The broken line shown in the figure indicates the position of each ring before movement or deformation.

Here again, the basic point of the modification is that the positions of the two fixed points P1 and P2 (the positions fixed by the fixing members 510 and 520) are immovable, and the positions of the two action points Q1 and Q2 move upward. That is the point. The detection ring 200 is gradually deformed from the positions of the fixed points P1 and P2 to the positions of the action points Q1 and Q2. When the force −Fz in the negative Z-axis direction acts on the force receiving body 100, the force receiving body 100 moves downward in the drawing. As a result, the modification of the detection ring 200 is upside down from that of FIG.

Next, let us consider what kind of change occurs in this basic structure when a moment about the Y axis acts on the force receiver 100 with the support substrate 300 fixed. FIG. 6 is a vertical cross-sectional view on the XZ plane showing a deformed state when a moment +My about the Y-axis is applied to the force receiving body 100 of the basic structure shown in FIG. In the present application, the sign of the moment acting around a predetermined coordinate axis is the positive direction of rotation of the right screw for advancing the right screw in the positive direction of the coordinate axis. For example, the rotation direction of the moment +My shown in FIG. 6 is the rotation direction for advancing the right screw in the Y-axis positive direction.

In this case as well, the support substrate 300 is fixed and thus immovable, but the force receiving body 100 receives the moment +My about the Y-axis positive rotation and rotates clockwise about the origin O in the figure. As a result, the action point Q1 moves downward and the action point Q2 moves upward. The detection ring 200 is gradually deformed from the positions of the fixed points P1 and P2 (positions fixed by the fixing members 510 and 520) to the positions of the action points Q1 and Q2. When a moment −My about the negative Y axis acts on the force receiving body 100, a phenomenon opposite to that in FIG. 6 occurs. When a moment +Mx about the positive X axis and a moment −Mx about the negative X axis act on the force receiving body 100, a phenomenon occurs in which the deformed state is rotated by 90° in the top view.

Finally, let us consider what kind of change occurs in this basic structure when a moment around the Z axis acts on the force receiving body 100 with the support substrate 300 fixed. FIG. 7 is a cross-sectional view in the XY plane showing a deformed state when a moment +Mz about the Z-axis is applied to the force receiving body 100 of the basic structure shown in FIG. In this case as well, the support substrate 300 is fixed and therefore immovable, but the force receiving body 100 receives a moment +Mz about the Z axis and rotates counterclockwise about the origin O in the figure.

As a result, a counterclockwise force in the figure is applied to the action points Q1 and Q2 of the detection ring 200. However, since the positions of the fixed points P1 and P2 of the detection ring 200 are fixed, the flexible detection ring 200 is deformed from the reference circular state to the distorted state as illustrated. Become. Specifically, as shown in the figure, between points P2-Q1 and between points P1-Q2, a pulling force acts on both ends of the quadrant of the detection ring 200 and the quadrant contracts inward, and points P1-Q1. Between the points and between points P2 and Q2, the pressing force acts on both ends of the quadrant of the detection ring 200, and the quadrant bulges outward, and is deformed into an elliptical shape as a whole. On the other hand, when a negative moment about the Z-axis -Mz is applied to the force receiving body 100, the force receiving body 100 rotates clockwise around the origin O in the figure, so that the deformation of FIG. The situation arises.

As described above, in a state where the support substrate 300 of the basic structure shown in FIG. 1 is fixed, when the force in each coordinate axis direction and the moment around each coordinate axis act on the force receiving body 100, the deformation mode that occurs in the detection ring 200 However, these deformation modes are different from each other, and the deformation amount is also different depending on the magnitude of the force or the moment applied. Therefore, by detecting the elastic deformation of the detection ring 200 and collecting information about the mode and size thereof, the force in each coordinate axis direction and the moment about each coordinate axis can be detected independently. This is the basic principle of the detection operation of the prior application force sensor. In the prior application force sensor, in order to perform detection based on such a principle, a capacitive element and a detection circuit are further added to the basic structure section described so far.

<<<<§2. Detection principle of prior application force sensor >>>
The prior application force sensor detects the direction and magnitude of the applied force and moment by measuring the displacement of a specific portion of the basic structure shown in FIG. A fixed auxiliary body 350 is added to detect this displacement.

FIG. 8 is a top view (upper diagram) and a side view (lower diagram) showing an example in which a fixed auxiliary body 350 for displacement detection is added to the basic structure shown in FIG. As shown in the figure, in this basic structure part, the detection ring 200 is arranged inside the force receiving body 100, and the fixing auxiliary body 350 is further arranged inside thereof. The fixing auxiliary body 350 is a columnar object having the Z axis as a central axis, and the lower surface is fixed to the upper surface of the support substrate 300. The outer peripheral surface of the stationary auxiliary body 350 faces the inner peripheral surface of the detection ring 200 with the gap H2 interposed therebetween.

FIG. 9 is a cross-sectional view (upper diagram) taken along the XY plane and a vertical cross-sectional view (lower diagram) taken along the VZ plane of the basic structure shown in FIG. Here, the V axis passes through the origin O in the XYZ three-dimensional Cartesian coordinate system, the positive region is located in the first quadrant of the XY plane, and the negative region is located in the third quadrant of the XY plane. It is the axis that forms °. The W axis passes through the origin O in the XYZ three-dimensional orthogonal coordinate system, the positive area is located in the second quadrant of the XY plane, and the negative area is located in the fourth quadrant of the XY plane, and is orthogonal to the V axis. It is an axis. The horizontal cross-sectional view shown in the upper part of FIG. 9 is a view in which the positive direction of the V-axis is the right direction and the positive direction of the W-axis is the upper direction, and the fixing auxiliary body 350 is added to the basic structure shown in the upper part of FIG. , Which corresponds to the figure rotated by 45° in the clockwise direction. Further, since the vertical cross-sectional view in the lower part of FIG. 9 is a vertical cross-sectional view taken along the VZ plane, the right direction is the V-axis positive direction.

As described in §1, on the detection ring 200, two fixed points P1 and P2 are arranged on the Y axis, and two action points Q1 and Q2 are arranged on the X axis. Here, four measurement points R1 to R4 (indicated by X marks) are further defined. As shown, the first measurement point R1 is in the V-axis positive area, the second measurement point R2 is in the W-axis positive area, the third measurement point R3 is in the V-axis negative area, and the fourth measurement point R4 is Each is arranged in the negative region of the W axis. After all, in the upper horizontal cross-sectional view of FIG. 9, the basic annular path B (indicated by a thick dashed line in the figure) is defined as a circle located between the outer peripheral contour circle and the inner peripheral contour circle of the detection ring 200. In this case, the points Q1, R1, P1, R2, Q2, R3, P2, R4 are arranged at regular intervals on the circular basic loop road B in this order. The four measurement points R1 to R4 are defined in such positions because the displacement caused by the elastic deformation of the detection ring 200 becomes the most prominent.

In order to detect the radial displacements of the four measurement points R1 to R4, the distances d1, d2, d3 and d4 indicated by the arrows in the transverse cross section of the upper part of FIG. 9 may be measured. These distances d1, d2, d3, d4 are located on the inner peripheral surface of the detection ring 200, the measurement target surface located near each measurement point R1, R2, R3, R4, and the outer periphery of the fixed auxiliary body 350, It is the distance from the opposing reference surface that faces the surface to be measured.If the distance is large, it indicates that the area near the measurement point is bulging in the radial direction.If the distance is small, the area near the measurement point is the radius. It shows that it is shrinking in the direction. Therefore, if a capacitance element that electrically detects these distances is prepared, it is possible to measure the deformation amount in the radial direction of the portion near each measurement point.

On the other hand, in order to detect the displacements of the four measurement points R1 to R4 in the vertical direction (Z-axis direction), the distances d5 and d7 and the distances d6 and d8 not shown in the vertical sectional view in the lower part of FIG. 9 are indicated. (The distance d6 may be a distance directly below the measurement point R2 located inside the fixed auxiliary body 350, and the distance d8 may be a distance directly below the measurement point R4 located in front of the fixed auxiliary body 350). These distances d5, d6, d7 and d8 are located on the lower surface of the detection ring 200 near the measurement points R1, R2, R3 and R4 and on the upper surface of the support substrate 300. Is a distance from the opposing reference surface, and if the distance is large, it means that the measurement point vicinity part is displaced upward, and if the distance is small, the measurement point vicinity part is downward. It means that it is displaced. Therefore, if a detection element that electrically detects these distances is prepared, it is possible to measure the amount of vertical deformation of the portion near each measurement point.

Thus, if the radial displacement and the vertical displacement of the four measurement points R1 to R4 can be measured, the overall deformation mode and deformation amount of the detection ring 200 can be grasped, and the XYZ cubic It is possible to detect the force in each coordinate axis direction and the six-axis component of the moment around each coordinate axis in the original Cartesian coordinate system. FIG. 10 is a top view showing distance measurement points necessary for detecting the 6-axis component. That is, in this example, as described above, the distance d1 (displacement in the radial direction) and the distance d5 (displacement in the vertical direction) are measured for the first measurement point R1, and the distance d2 for the second measurement point R2. (Radial displacement) and distance d6 (upward and downward displacement) are measured, and distance d3 (radial displacement) and distance d7 (upward and downward displacement) are measured at the third measurement point R3, At the fourth measurement point R4, the distance d4 (displacement in the radial direction) and the distance d8 (displacement in the vertical direction) will be measured.

FIG. 11 shows changes in the distances d1 to d8 when a force in each coordinate axis direction and a moment about each coordinate axis act on the force receiving body 100 with the support substrate 300 fixed in the basic structure shown in FIG. Is a table showing. In this table, "+" indicates that the distance increases, "-" indicates that the distance decreases, and "0" indicates that the distance does not change. The fact that such a result is obtained can be easily understood in consideration of the specific modification of the detection ring 200 described in §1.

For example, when the force +Fx in the positive direction of the X axis acts on the force receiver 100, the detection ring 200 causes the quadrants between points P1 and Q1 and between points P2 and Q1 to move inward as shown in FIG. The contraction and the quadrants between points P1-Q2 and between points P2-Q2 are deformed so as to bulge outward. Therefore, the distances d1 and d4 are small and the distances d2 and d3 are large. At this time, since the detection ring 200 is not vertically deformed, the distances d5 to d8 do not change. The +Fx row in the table of FIG. 11 shows such a result. For the same reason, when the force +Fy in the positive direction of the Y-axis is applied, the result shown in the row +Fy in the table of FIG. 11 is obtained.

Further, when the force +Fz in the Z-axis positive direction acts on the force receiving body 100, the detection ring 200 is deformed as shown in FIG. 5, so that the distances d5 to d8 increase. At this time, since the detection ring 200 is not deformed in the radial direction, the distances d1 to d4 do not change. The +Fz row in the table of FIG. 11 shows such a result.

Then, when a moment +My about the Y-axis is applied to the force receiving body 100, the detection ring 200 is deformed as shown in FIG. 6, the right half of the figure is displaced downward, and the left half of the figure is upward. The distances d5 and d8 are reduced and the distances d6 and d7 are increased. At this time, since the detection ring 200 is not deformed in the radial direction, the distances d1 to d4 do not change. The +My row in the table of FIG. 11 shows such a result. For the same reason, when the positive X-axis moment +Mx acts, the result shown in the row of +Mx in the table of FIG. 11 is obtained.

Finally, when a moment +Mz about the Z-axis is applied to the force receiving body 100, the detection ring 200 is deformed as shown in FIG. 7, and the quadrant between the points P1 and Q1 and between the points P2 and Q2. The circular arc bulges outward, and the quadrant circular arc between points P1-Q2 and between points P2-Q1 is deformed so as to contract inward. Therefore, the distances d1 and d3 increase, and the distances d2 and d4 decrease. At this time, since the detection ring 200 is not vertically deformed, the distances d5 to d8 do not change. The +Mz row in the table of FIG. 11 shows such a result.

The table of FIG. 11 shows the results when a positive force and a positive moment are applied. However, when a negative force and a negative moment are applied, “+” and “−” are given. The result will be reversed. After all, the change pattern of the distances d1 to d8 is different in each case where the six-axis components act, and the greater the applied force or moment, the greater the amount of change in the distance. Therefore, if the detection circuit performs a predetermined calculation based on the measured values of the distances d1 to d8, the detected values of the six axis components can be independently output.

The prior application force sensor is a basic structure shown in FIG. 8 with a capacitance element and a detection circuit further added, and is capable of electrically detecting a change in capacitance value of the capacitance element arranged in each portion. Is used to measure the displacement at a specific location and detect the direction and magnitude of the applied force and moment.

FIG. 12 is a horizontal cross-sectional view (upper diagram) taken along the XY plane and a vertical cross-sectional view (lower diagram) taken along the VZ plane of the force sensor configured by adding a capacitive element to the basic structure shown in FIG. Figure)). A comparison between the basic structure shown in FIG. 9 and the force sensor shown in FIG. 12 reveals that the latter has 16 electrodes E11 to E18 and E21 to E28. The eight sets of capacitive elements composed of these 16 electrodes function as detection elements for measuring the above-described eight distances d1 to d8.

As shown in the horizontal cross-sectional view in the upper part of FIG. 12, displacement electrodes E21 to E24 are provided on the inner peripheral surface of the detection ring 200 near the four measurement points R1 to R4 (measurement target surface), respectively. ing. Displacement electrodes E25 to E28 (indicated by broken lines in the figure) are provided on the lower surface of the detection ring 200 near the four measurement points R1 to R4 (measurement target surface). These eight displacement electrodes E21 to E28 are literally electrodes that are displaced by the deformation of the detection ring 200.

On the other hand, eight fixed electrodes E11 to E18 are provided at positions (opposite reference planes) facing these eight displacement electrodes E21 to E28. The eight fixed electrodes E11 to E18 are literally electrodes fixed directly or indirectly to the support substrate 300, and always maintain fixed positions regardless of the deformation of the detection ring 200. Specifically, fixed electrodes E11 to E14 are provided on the outer peripheral surface of the cylindrical fixed auxiliary body 350 at positions facing the displacement electrodes E21 to E24, and these electrodes are interposed via the fixed auxiliary body 350. It is indirectly fixed on the support substrate 300. Fixed electrodes E15 to E18 are directly fixed on the upper surface of the support substrate 300 at positions facing the displacement electrodes E25 to E28 (only the displacement electrodes E15 and E17 appear in the vertical sectional view in the lower part of FIG. 12). However, the displacement electrode E16 is located in the back of the fixed auxiliary body 350, and the displacement electrode E18 is located in front of the fixed auxiliary body 350).

In the drawings of the present application, for convenience of illustration, the actual thickness of each displacement electrode and each fixed electrode is ignored. For example, when each electrode is composed of a vapor deposition layer or a plating layer, its thickness is about several μm, and the thickness of each electrode E11 to E28 shown in FIG. It's not.

After all, in the case of the example shown in FIG. 12, eight sets of displacement electrodes E21 to E28 provided on the measurement target surface located in the vicinity of each measurement point R1 to R4 on the inner peripheral surface and the lower surface of the detection ring 200 and the fixing auxiliary. Eight sets of fixed electrodes E11 to E18 provided on the opposing reference planes defined on the outer peripheral surface of the body 350 and the upper surface of the support substrate 300 at positions facing the respective measurement target surfaces form eight capacitive elements. Will be configured. Then, the prior application force sensor measures the displacements at the respective measurement points R1 to R4 by electrically detecting the capacitance values of these eight sets of capacitive elements, and based on the table shown in FIG. The direction and magnitude of the force and moment acting on the force receiving body 100 will be detected.

As described above, the prior application force sensor can be configured by using a simple basic structure portion as shown in FIG. 12, but since it is necessary to arrange the capacitive elements at various places, There is no choice but to complicate the structure of the electrodes. Specifically, in order to add a capacitive element to the basic structure portion, a step of forming an electrode layer parallel to the substrate surface (XY plane) like the fixed electrodes E15 to E18 and the displacement electrodes E25 to E28. And the step of forming an electrode layer perpendicular to the substrate surface (XY plane) like the fixed electrodes E11 to E14 and the displacement electrodes E21 to E24. Generally, the former process is relatively easy because a method widely used in the semiconductor manufacturing process and the like can be used, but the latter process needs to incorporate a complicated method and is mass-produced. The problem is likely to occur above.

In addition, the relative position of the pair of electrodes forming each capacitance element is a significant factor that affects the detection accuracy. In particular, as in the example shown in FIG. 12, when a plurality of capacitive elements are arranged with symmetry and difference detection is performed using these, the counter electrodes are arranged in parallel for each individual capacitive element. It is necessary to adjust such that the electrode intervals of the plurality of capacitance elements are equal to each other. For this reason, the prior application force sensor has a problem that the production efficiency is reduced and the cost is increased when it is used commercially.

In order to solve such a problem in the force sensor of the prior application, the present invention adopts a structure in which a detection portion that causes elastic deformation is provided at a specific position of the detection ring, thereby improving the degree of freedom in design and improving the production efficiency. We propose a new device that can improve the Hereinafter, the present invention will be described in detail based on specific embodiments.

<<<< §3. Basic embodiment of the present invention >>>
<3-1. Structure of detection ring>
FIG. 13 is a perspective view (FIG. (a)), a side view (FIG. (b)) and a bottom view of a detection ring 600 used in the force sensor according to the basic embodiment (first embodiment) of the present invention. Figure (c)). The detection ring 200 used in the prior application force sensor shown in FIG. 1 is a simple annular structure, whereas the detection ring 600 used in the force sensor of the present application shown in FIG. Detection portions D1 to D4 configured by combining plate pieces that elastically deform are provided at four positions of the annular structure.

In other words, the detection ring 600 shown in FIG. 13 is a member obtained by subjecting the detection ring 200 shown in FIG. 1 to partial material removal processing, and the portion subjected to this material removal processing. Thus, the detection parts D1 to D4 as illustrated are formed. The detection ring 200 shown in FIG. 1 is obtained by forming a through opening in the center of a plate-shaped member arranged with the Z axis as the central axis. The detection ring 600 shown in FIG. 13 is obtained by subjecting the detection ring 200 thus obtained to a partial material removal process. The four sets of detection units D1 to D4 are the parts obtained by such material removal processing. However, when the detection ring 600 is actually mass-produced, it is not always necessary to perform material removal processing, and for example, casting using a mold, resin molding, press processing, or the like may be performed.

Here, for convenience of explanation, an XYZ three-dimensional coordinate system is defined as shown in the figure, and a state in which the detection ring 600 is arranged on the XY plane with the Z axis as the central axis is shown. FIG. 13A is a perspective view of the detection ring 600 as seen obliquely from below. As shown in the figure, the detection ring 600 has four sets of detection parts D1 to D4 and four sets of connection parts L1 to L4 that connect these detection parts D1 to D4 to each other. That is, the detection ring 600 has a structure in which the connecting portions L1 to L4 are respectively inserted between the detecting portions D1 to D4.

As shown in the detection section D4 of the side view of FIG. 13(b) (only the outer peripheral surface portion is shown in order to avoid complexity of the figure), the detection section D4 in this embodiment is The deformable portion 61, the second deformable portion 62, and the displacing portion 63 are composed of three plate-shaped pieces (leaf springs). The other detectors D1 to D3 have the same structure. As described above, since each of the detection units D1 to D4 is configured by the plate-shaped piece having a thinner wall thickness than each of the connection units L1 to L4, the detection units D1 to D4 are more likely to be elastically deformed than each of the connection units L1 to L4. have. Therefore, as described later, when an external force acts on the detection ring 600, elastic deformation of the detection ring 600 based on the external force occurs concentrated on the detection portions D1 to D4, and the elastic deformation of the connection portions L1 to L4 is: It is practically negligible.

As described above, since the detection ring 200 used in the prior application force sensor has a uniform annular structure, elastic deformation occurs over the entire ring when an external force is applied, whereas the force sensor of the present application. In the detection ring 600 used for, the deformation concentrates on the detection portions D1 to D4 where elastic deformation easily occurs. Therefore, it is possible to cause more efficient deformation and more efficient detection. Specifically, not only the detection sensitivity is increased, but also the shape and structure of the detection unit are devised, whereby the mode of elastic deformation can be freely set. Note that a specific mode of elastic deformation of the illustrated detection units D1 to D4 will be described in detail later.

FIG. 13(c) is a bottom view of the detection ring 600 shown in FIG. 13(a), which is looked up from below, and when the X axis is taken in the right direction, the Y axis is an axis that faces downward. As shown in the drawing, clockwise from the connecting portion L1 arranged on the X axis as a starting point, the connecting portion L1, the detecting portion D1, the connecting portion L2, the detecting portion D2, the connecting portion L3, the detecting portion D3, the connecting portion L4. The detectors D4 are arranged in this order. As will be described later, fixed points P1 and P2 (shown by black circles) on the Y-axis are fixed to the support substrate, and external force applied from the force receiving body to action points Q1 and Q2 (shown by white circles) on the X-axis. Works. As a result, elastic deformation occurs in each of the detection units D1 to D4 according to the external force.

FIG. 14 is a top view showing the region distribution of the detection ring 600 shown in FIG. 13 (the mesh hatching is for showing the regions of the detection parts D1 to D4, and not for showing the cross section). Since it is a top view, contrary to FIG. 13(c), L1, D1, L2, D2, L3, D3, L4, D4 are arranged in this order on the detection ring 600 in a counterclockwise direction. As shown in the figure, on the XY plane, the V axis is defined as a coordinate axis obtained by rotating the X axis counterclockwise by 45° about the origin O, and the Y axis is rotated counterclockwise by 45° about the origin O. The W axis is defined as the coordinate axis. <I>, <II>, <III>, and <IV> in the figure show the first to fourth quadrants in the XY two-dimensional coordinate system. The four sets of detectors D1, D2, D3, D4 are arranged in the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant, respectively.

FIG. 15 is a plan view showing the basic ring road B defined on the XY plane and the points defined on the basic ring road B for the detection ring 600 shown in FIG. The basic annular path B indicated by a thick dashed line in the figure is a circle centered on the origin O arranged on the XY plane, and the detection ring 600 is an annular structure extending along the basic annular path B. In the figure, the positions of the inner contour line and the outer contour line of the detection ring 600 are shown by solid lines. In the illustrated embodiment, the basic annular path B is a circle on the XY plane that passes through the intermediate position between the inner contour line and the outer contour line of the detection ring 600, and the annular thick portion of the detection ring 600 (the connecting portion L1). ~L4) center line.

The four sets of detection points R1 to R4 are defined as points on the basic ring road B. Specifically, the first detection point R1 is defined at the intersection position of the positive V axis and the basic ring road B, and the second detection point R2 is the intersection point of the positive W axis and the basic ring road B. The third detection point R3 is defined as a position, the third detection point R3 is defined as an intersection position between the negative V axis and the basic ring road B, and the fourth detection point R4 is defined as an intersection point between the negative W axis and the basic ring road B. Defined in position. These detection points R1 to R4 indicate the arrangement of the detection units D1 to D4, respectively. That is, as shown as a meshed hatching area in FIG. 14, the first detection unit D1 is arranged at the position of the first detection point R1 and the second detection unit D2 is arranged at the position of the second detection point R2. The third detector D3 is arranged at the position of the third detection point R3, and the fourth detector D4 is arranged at the position of the fourth detection point R4.

On the other hand, points P1 and P2 indicated by black circles in FIG. 15 are fixed points, and points Q1 and Q2 indicated by white circles are action points. As will be described later, the fixed points P1 and P2 are points fixed to the support substrate 300, and the action points Q1 and Q2 are points where the force from the force receiving body 100 acts. In the illustrated example, the fixed points P1 and P2 are defined at the intersection positions of the Y axis and the basic ring road B, and the action points Q1 and Q2 are defined at the intersection positions of the X axis and the basic ring road B. There is. Therefore, in the force sensor using this detection ring 600, the force or moment acting on the two points Q1 and Q2 on the X axis is fixed to the two points P1 and P2 on the Y axis, and the force or moment acting on the V axis and W The detection is performed based on the elastic deformation of the four sets of detection units D1 to D4 arranged at the detection points R1 to R4 on the axis.

As shown in FIG. 15, the fixed points P1 and P2 and the action points Q1 and Q2 are alternately arranged along the basic ring road B. As will be described later, such an alternating arrangement is important for effectively deforming the detection ring 600 when an external force to be detected acts. Further, the four sets of detection points R1 to R4 are arranged between the adjacent fixed points and action points. Such an arrangement is also important for causing effective displacement of the detection units D1 to D4 when an external force to be detected acts.

<3-2. Structure of basic embodiment>
Next, the structure of the force sensor according to the basic embodiment (first embodiment) of the present invention will be described. FIG. 16 is a top view (upper view) of the basic structure of the force sensor according to the embodiment and a side sectional view (lower view) taken along the XZ plane. As shown in the figure, the basic structure includes a force receiving body 100, a detection ring 600, and a support substrate 300.

As described in detail in §3-1, the detection ring 600 is an annular member having the structure shown in FIG. 13, and has four sets of detection units D1 to D4. The force receiving body 100 is an annular member arranged so as to surround the outside of the detection ring 600. On the other hand, the support substrate 300 is a disk-shaped member arranged below the detection ring 600 and the force receiving body 100 as shown in the side sectional view of the lower stage. The inner peripheral surface of the force receiving body 100 and the outer peripheral surface of the detection ring 600 are connected by two connecting members 410 and 420 arranged at positions along the X axis, and the lower surface of the detection ring 600 and the support substrate. The upper surface of 300 is connected by fixing members 510 and 520 arranged at positions along the Y axis.

Comparing the basic structure of the prior invention shown in FIG. 2 with the basic structure of the present invention shown in FIG. 16, the essential difference between the two is that the detection ring 200 in the former is replaced with the detection ring 600 in the latter. It is the only point. The other constituent elements are slightly different in size and shape, but since there is no difference in the essential function, in FIG. 16, the same reference numerals are used for the corresponding constituent elements except for the detection ring. It is shown using. The detection ring 200 shown in FIG. 2 is a simple washer-shaped annular structure, whereas the detection ring 600 shown in FIG. 16 is an annular structure having detection portions D1 to D4 at four locations. For this reason, when an external force (force or moment) acts on the detection ring 600, as described above, the deformation concentrates on the detection portions D1 to D4.

Therefore, the structure of each of the detection units D1 to D4 and its modification will be described below. FIG. 17 is a partial cross-sectional view showing the detailed structure of the detection parts D1 to D4 of the detection ring 600 shown in FIG. All four detection units D1 to D4 have the same structure. The detection unit D shown in FIG. 17 is a representative of these four sets of detection units D1 to D4, and shows a cross-sectional portion when the detection ring 600 is cut along a cylindrical surface including the basic annular path B. 17(a) shows a state in which no external force is applied, FIG. 17(b) shows a state in which a compressive force f1 is applied to the detection portion D by the action of the external force, and FIG. 17(c) shows a state in which the external force acts. The state where the extension force f2 acts on the part D is shown.

As shown in FIG. 17A, the connecting portions L are located on the left and right sides of the detecting portion D. The connecting portion L corresponds to one of the four connecting portions L1 to L4. For example, when the detection unit D shown in FIG. 17(a) is the fourth detection unit D4 shown in FIG. 13, the connecting portion L arranged on the right side of the detecting unit D is the connecting portion L1 shown in FIG. And the connecting portion L arranged on the left side thereof corresponds to the connecting portion L4 shown in FIG.

As shown in the figure, the detection unit D includes a first deformation unit 61 that elastically deforms due to the action of an external force that is a detection target, a second deformation unit 62 that elastically deforms due to the action of an external force that is a detection target, and a second deformation unit 62. A first deformable portion 61 and a second deformable portion 62 that are displaced by elastic deformation of the second deformable portion 62, and an end portion of the connecting portion L arranged on the left side and a connecting portion arranged on the right side. It is arranged between the end portion of the portion L.

In the case of the example shown here, the first deformable portion 61 is composed of a flexible first plate-shaped piece, and the second deformable portion 62 is composed of a flexible second plate-shaped piece. The displacement portion 63 is configured by the third plate-shaped piece. Actually, the detection ring 600 is composed of a structure made of the same material such as metal (stainless steel, aluminum, etc.) or synthetic resin (plastic, etc.). The first plate-shaped piece 61, the second plate-shaped piece 62, and the displacement portion 63 are plate-shaped members that are thinner than the connecting portion L, and therefore have flexibility.

In the case of the example shown here, the displacement portion 63 is also a thin plate-shaped member and thus has flexibility, but the displacement portion 63 does not necessarily have to be a flexible member. Not (of course, flexible). The role of the displacement portion 63 is to generate displacement when an external force is applied. In order to generate such displacement, the first deformable portion 61 and the second deformable portion 62 have flexibility. It's enough if there is. Therefore, the displacement portion 63 does not necessarily have to be configured by a thin plate-shaped member, and may be a thicker member. On the other hand, the connecting portion L may have a certain degree of flexibility, but in order to effectively deform the first deforming portion 61 and the second deforming portion 62 by the applied external force. It is preferable that the connecting portion L is not deformed as much as possible.

The outer end of the first deformable portion 61 is connected to the connecting portion L adjacent thereto, and the inner end of the first deformable portion 61 is connected to the displacement portion 63. The outer end of the second deformable portion 62 is connected to the connecting portion L adjacent thereto, and the inner end of the second deformable portion 62 is connected to the displacement portion 63. In the case of the example shown in FIG. 17(a), the first deformable portion, the second deformable portion, and the displaceable portion are the first plate-shaped piece 61, the second plate-shaped piece 62, and the third plate-shaped piece, respectively. The outer end (left end) of the first plate-shaped piece 61 is connected to the right end of the connecting portion L arranged on the left side, and the inner end (right end) of the first plate-shaped piece 61. ) Is connected to the left end of the third plate-like piece 63, and the outer end (right end) of the second plate-like piece 62 is connected to the left end of the connecting portion L arranged on the right side, and The inner end of the plate-shaped piece 62 is connected to the right end of the third plate-shaped piece 63.

As described above, the detection unit D is arranged at the position of the detection point R defined on the basic ring road B. The normal line N shown in FIG. 17(a) is a normal line that stands at the position of the detection point R and is orthogonal to a basic plane (XY plane) including the basic loop road B, and the detection unit D has this normal line N. Are arranged so that they are in the center. In addition, in the cross-sectional view of FIG. 17A, the first plate-shaped piece 61 and the second plate-shaped piece 62 are inclined with respect to the normal line N, and The inclination direction (downward to the right) and the inclination direction (upward to the right) of the second plate-shaped piece 62 are opposite. Particularly, in the case of the illustrated example, the cross-sectional shape of the detection unit D is line-symmetric with respect to the normal line N, and the upper and lower surfaces of the third plate-shaped piece 63 form surfaces parallel to the XY plane.

Thus, with respect to the cross section including the basic annular path B, the inclination direction of the first plate-shaped piece 61 and the inclination direction of the second plate-shaped piece 62 with respect to the normal line N are opposite to each other. The displacement direction of the third plate-shaped piece 63 (displacement portion) is opposite between when the compressive force f1 acts in the direction along the path B and when the extension force f2 acts. This is convenient for performing difference detection using a plurality of capacitive elements, as will be described later.

That is, as shown in FIG. 17(b), when a compressive force f1 (white arrow in the figure) acts on the detection unit D in the direction along the basic annular road B, the detection unit D has a reduced width. Since a stress is applied in the direction, the postures of the first plate-shaped piece 61 and the second plate-shaped piece 62 change to a more vertical standing state. As a result, the third plate-shaped piece 63 (displacement portion) is displaced downward as indicated by a black arrow in the figure. On the other hand, as shown in FIG. 17(c), when the extension force f2 (white arrow in the figure) acts on the detection unit D in the direction along the basic annular road B, the detection unit D is widened in width. Since stress is applied in the direction, the postures of the first plate-shaped piece 61 and the second plate-shaped piece 62 change to a more horizontal lying state. As a result, the third plate-shaped piece 63 (displacement portion) is displaced upward as indicated by a black arrow in the figure.

As described above, the deformation mode in the case where the compressive force f1 or the extension force f2 acts on the detection unit D in the direction along the basic annular path B has been described, but of course, in the case where the external force acts in the other direction, A different modification from that shown in FIG. 17 will occur. For example, in FIG. 17A, a force for moving the connecting portion L on the right side upward in the figure is applied, and at the same time, a force for moving the connecting portion L on the left side downward in the figure is applied. Then, a deformation that is asymmetric with respect to the normal line N occurs. However, as will be described later, in the force sensor according to the basic embodiment shown here, it is sufficient to grasp the operating principle when substantially considering only the modification shown in FIG.

<3-3. Detection principle by capacitive element>
In the basic embodiment of the present invention, the direction and magnitude of the applied external force are detected by using the displacement of the displacement portion 63 generated in the four sets of detection portions D1 to D4. A capacitive element is used as a detection element for detecting the. In other words, the force sensor according to the basic embodiment of the present invention is configured by adding the capacitive element and the detection circuit to the basic structure shown in FIG.

FIG. 18 is a partial cross-sectional view showing a detailed structure in which electrodes are provided at predetermined portions of the detection portions D1 to D4 of the detection ring 600 shown in FIG. 13 and the supporting substrate 300 facing the detection portions D1 to D4. In FIG. 18 as well, the detector D represents four sets of detectors D1 to D4, and shows a cross-sectional portion when the detector ring 600 is cut along a cylindrical surface including the basic annular path B. .. That is, a part of the detection ring 600 shown in the upper part of FIG. 18 corresponds to a part of the detection ring 600 shown in FIG.

As described above, both surfaces of the third plate-shaped piece 63 form surfaces parallel to the XY plane including the basic annular path B when no external force (force or moment) is applied. On the other hand, the support substrate 300 is arranged so that its upper and lower surfaces are parallel to the XY plane. Therefore, as shown in the figure, the third plate-shaped piece 63 (displacement portion) and the opposing surface of the support substrate 300 are parallel to each other. Moreover, in the case of the embodiment shown here, since the cross-sectional shape of the detecting portion D is line symmetric with respect to the normal line N, the compressive force f1 or the expanding force f2 as shown in FIGS. When the third plate-shaped piece 63 (displacement portion) is displaced, the third plate-shaped piece 63 (displacement portion) is displaced in parallel with the vertical direction in the figure, and the third plate-shaped piece 63 (displacement portion) and the opposing surface of the support substrate 300 are opposed to each other. Are always maintained in parallel. Of course, when the third plate-shaped piece 63 is deformed by the external force (f1, f2), the parallel state is not maintained, but the distance between the electrodes E1 and E2 described later is still equal to the external force (f1, f2). If there is a change on the basis of the above, no problem will occur in the detection operation.

In order to detect the displacement of the displacement portion, as shown in the figure, the fixed electrode E1 is fixed to the upper surface of the support substrate 300 via the insulating layer I1, and the lower surface of the third plate-shaped piece 63 (displacement portion) is The displacement electrode E2 is fixed via the insulating layer I2. If the supporting substrate 300 is maintained in a fixed state, the position of the fixed electrode E1 is fixed, but the position of the displacement electrode E2 is displaced along with the displacement of the third plate-shaped piece 63 (displacement portion). As shown in the figure, the fixed electrode E1 and the displacement electrode E2 are arranged at positions facing each other, and a capacitive element C is constituted by both. Here, when the third plate-shaped piece 63 (displacement portion) moves in the vertical direction in the drawing, the distance between the pair of electrodes forming the capacitive element C changes. Therefore, the displacement direction (upper or lower in the figure) and the displacement amount of the third plate-shaped piece 63 (displacement portion) can be detected based on the capacitance value of the capacitive element C.

Specifically, as shown in FIG. 17(b), when the compressive force f1 acts on the detection unit D, the distance between both electrodes is reduced, and the capacitance value of the capacitive element C is increased. As shown in FIG. 5, when the extension force f2 acts on the detection unit D, the distance between both electrodes increases and the capacitance value of the capacitive element C decreases. FIG. 18 shows an example in which the capacitive element C is formed for the detection unit D, but of course, in actuality, the fixed electrode E1 and the displacement electrode are respectively provided for the four sets of detection units D1 to D4 shown in FIG. E2 is provided, and four sets of capacitive elements C1 to C4 are formed. A specific method for detecting each of the applied external force components by using these four sets of capacitive elements C1 to C4 will be described in the following §3-4.

In the embodiment shown in FIG. 18, the displacement electrode E2 is fixed to the third plate-shaped piece 63 (displacement portion) via the insulating layer I2. This is because the detection ring 600 is made of a conductive material such as metal. This is because it is composed of materials. Similarly, the fixed electrode E1 is fixed to the supporting substrate 300 via the insulating layer I1, but this is because the supporting substrate 300 is made of a conductive material such as metal. That is, in the case of the basic structure shown in FIG. 16, since the force receiving body 100, the detection ring 600, and the support substrate 300 are all made of a conductive material such as metal, the displacement electrode E2 is disposed on the surface of the displacement portion 63. And the fixed electrode E1 is formed on the surface of the support substrate 300 via the insulating layer I1.

Therefore, when the detection ring 600 (of which at least the surface on which the displacement electrode E2 is formed) is made of an insulating material such as resin, it is not necessary to provide the insulating layer I2. Similarly, when the support substrate 300 (of which at least the surface on which the fixed electrode E1 is formed) is made of an insulating material such as resin, the insulating layer I1 need not be provided.

When the detection ring 600 is made of a conductive material such as metal, a part of the lower surface of the detection ring 600 can be used as the displacement electrode E2. For example, in the embodiment shown in FIG. 18, if the detection ring 600 is made of a conductive material, the third plate-shaped piece 63 (displacement portion) becomes a conductive plate, so that it itself functions as a displacement electrode. Will be fulfilled. Therefore, it is not necessary to separately provide the displacement electrode E2. In this case, electrically, the entire surface of the detection ring 600 has the same potential, but the portions that actually function as the displacement electrodes E2 of the four sets of capacitive elements C1 to C4 are the four sets provided individually. That is, only the area facing the fixed electrode E1. Therefore, the four sets of capacitance elements C1 to C4 behave as separate capacitance elements, respectively, and there is no problem in principle.

On the contrary, when the supporting substrate 300 is made of a conductive material such as metal, a part of the upper surface of the supporting substrate 300 can be used as the fixed electrode E1. For example, in the embodiment shown in FIG. 18, if the supporting substrate 300 is made of a conductive material, a part of its upper surface will function as a fixed electrode. Therefore, it is not necessary to separately provide the fixed electrode E1. In this case, electrically, the entire surface of the support substrate 300 is at the same potential, but the portions that actually function as the fixed electrodes E1 of the four sets of capacitive elements C1 to C4 are the four sets provided individually. That is, only the region facing the displacement electrode E2 of. Therefore, the four sets of capacitance elements C1 to C4 behave as separate capacitance elements, respectively, and there is no problem in principle.

In this way, if the detection ring 600 is made of a conductive material such as metal, or if the support substrate 300 is made of a conductive material such as metal, individual displacement electrodes E2 and individual fixed electrodes E1 are formed. Since the step of providing can be omitted, the production efficiency can be further improved.

However, if such an omitted structure is adopted, the entire detection ring 600 or the entire support substrate 300 serves as a common electrode, and stray capacitance is formed in various unintended portions. For this reason, noise components are likely to be mixed in the detected value of the electrostatic capacitance, and the detection accuracy may decrease. Therefore, in the case of a force sensor that requires highly accurate detection, even if the detection ring 600 and the support substrate 300 are made of a conductive material, they are insulated from each other as in the embodiment shown in FIG. The individual displacement electrodes E2 and the individual fixed electrodes E1 are preferably provided via layers.

The easiness of elastic deformation of the detection unit D is a parameter that affects the detection sensitivity of the sensor. By using the detection unit D that is easily elastically deformed, it is possible to realize a sensor with high sensitivity that can detect even a small external force, but the maximum value of the external force that can be detected is suppressed. On the contrary, if the detection unit D that is not easily elastically deformed is used, the maximum value of the external force that can be detected can be made large, but the sensitivity is lowered, so that it becomes impossible to detect a minute external force.

The easiness of elastic deformation of the detection unit D depends on the thickness of the first deformation unit 61 (first plate-shaped piece) and the second deformation unit 62 (second plate-shaped piece) It is determined depending on the shape such as (easy), width (more elastically deformed as it is narrower), length (more elastically deformed as it is longer), and further depending on its material. Further, the detection unit D can be designed with a structure in which the displacement portion 63 (third plate-shaped piece) is elastically deformed. Therefore, in practice, the size and material of each part of the detection unit D may be appropriately selected according to the application of the force sensor.

Note that, as described above, in the drawings of the present application, for convenience of illustration, the actual size of each part is ignored. For example, in FIG. 18, the thicknesses of the fixed electrode E1 and the displacement electrode E2 and the thicknesses of the insulating layer I1 and the insulating layer I2 are drawn so as to be substantially the same as the thicknesses of the plate-shaped pieces 61, 62, 63. However, each of these electrodes and insulating layers can be formed by vapor deposition or plating, and the thickness thereof can be set to about several μm. On the other hand, the thickness of each plate-shaped piece 61, 62, 63 is preferably designed to be thicker in consideration of practical strength. For example, when it is made of metal, it is set to about 1 mm. Is preferred.

On the other hand, the force receiving body 100 and the support substrate 300 shown in FIG. 16 do not have to be members that cause elastic deformation in principle of detecting an external force. Rather, in order for the applied external force to contribute 100% to the deformation of the detection ring 600, it is preferable that the force receiving body 100 and the support substrate 300 are completely rigid bodies. In the illustrated example, the reason why the annular structure is used as the force receiving body 100 is not to facilitate elastic deformation, but is arranged on the outside of the detection ring 600 to form an overall thin force sensor. This is because.

That is, in the case of the basic embodiment shown in FIG. 16, each of the force receiving body 100, the detection ring 600, and the support substrate 300 can be configured by a flat structure having a small thickness in the Z-axis direction, and moreover, the force receiving body. Since the structure in which 100 is arranged outside the detection ring 600 is adopted, it becomes possible to set the axial length (length in the Z-axis direction) of the entire sensor to be short. In addition, in the case of the basic embodiment shown in FIG. 16, it is sufficient to dispose all the displacement electrodes E2 on the lower surface of the detection ring 600 (the lower surface of each displacement portion 63 of the four sets of detection portions D1 to D4). You can expect the effect of improving.

This effect can be easily understood by comparing with the configuration of the capacitive element of the prior application force sensor illustrated in FIG. In the prior application force sensor illustrated in FIG. 12, by the displacement electrodes E21 to E24 formed on the inner peripheral surface of the detection ring 200 and the fixed electrodes E11 to E14 formed on the outer peripheral surface of the stationary auxiliary body 350. Four sets of capacitive elements are formed, and further four sets of capacitive elements are formed by the displacement electrodes E25 to E28 formed on the lower surface of the detection ring 200 and the fixed electrodes E15 to E18 formed on the upper surface of the support substrate 300. To be done.

As described above, in order to form both the electrode along the horizontal surface and the electrode along the vertical surface, a process that requires a certain amount of time is required, and a large work load is required for the position adjustment. Therefore, the production efficiency is unavoidably reduced. For example, even if the central axis of the fixed auxiliary body 350 is slightly deviated from the Z axis, the positions of the fixed electrodes E11 to E14 are changed and the electrostatic capacitance value of the capacitive element is changed. Of course, the same applies when the central axis of the detection ring 200 is slightly deviated from the Z axis. Therefore, in the manufacturing process of the prior application force sensor, when the fixing auxiliary body 350 and the detection ring 200 are attached, the central axes need to be aligned with high accuracy.

On the other hand, in the case of the force sensor using the basic structure shown in FIG. 16, the displacement electrodes E2 are formed on the lower surfaces of the displacement portions 63 of the four detection units D1 to D4, and the displacement electrodes E2 are formed on the support substrate 300. The fixed electrode E1 may be formed at each of the facing positions. Both electrodes are electrodes along a horizontal plane, and accurate thickness control is possible by using a general film forming process. Moreover, the electrodes are not required to have strict accuracy in the formation position in the horizontal direction. Further, since the distance between the displacement electrode E2 and the fixed electrode E1 facing the displacement electrode E2 is defined by the height dimension of the fixed members 510 and 520, the positional accuracy of each electrode in the vertical direction can be easily ensured. it can. Therefore, even in the case of performing commercial mass production, it is not possible to make the counter electrodes parallel to each other for each capacitance element and to adjust the electrode intervals for a plurality of capacitance elements to be equal to each other. It's easy. For this reason, the force sensor according to the basic embodiment described here can ensure high production efficiency.

In the case of the embodiment shown in FIG. 18, the size of the fixed electrode E1 (planar size, that is, the planar size, that is, the occupied area of the projected image on the XY plane) is larger than that of the displacement electrode E2. , Occupying area of the projected image on the XY plane) is set larger. This is so that even if the displacement electrode E2 is displaced in the left-right direction of the drawing or in the direction perpendicular to the paper surface of the drawing (direction along the XY plane), the facing area of the displacement electrode E2 with respect to the fixed electrode E1 does not change. It is a consideration to do. In other words, even if the displacement electrode E2 is displaced in any of the three-dimensional directions, the effective area of the capacitive element C is always maintained constant as long as the positional relationship between both electrodes is maintained in parallel.

FIG. 19 is a diagram showing the principle that the effective area of the capacitive element C is maintained constant even when the relative position of the displacement electrode E2 with respect to the fixed electrode E1 changes in this way. Now, consider a case where a pair of electrodes EL and ES are arranged so as to face each other, as shown in FIG. Both electrodes EL and ES are arranged so as to be parallel to each other at a predetermined interval, and form a capacitive element. However, the electrode EL has a larger area than the electrode ES, and when the contour of the electrode ES is projected on the surface of the electrode EL to form an orthogonal projection image, the projected image of the electrode ES is the surface of the electrode EL. Completely contained within. In this case, the effective area of the capacitive element is the area of the electrode ES.

FIG. 19(b) is a side view of the pair of electrodes ES, EL shown in FIG. 19(a). The hatched area in the figure is a portion that substantially functions as a capacitive element, and the effective area as a capacitive element is the area of this hatched electrode (that is, the area of the electrode ES). Become.

Now, consider a vertical plane U as shown by a dashed line in the figure. The electrodes ES and EL are both arranged so as to be parallel to the vertical plane U. Here, if the electrode ES is moved vertically upward along the vertical surface U, the facing portion on the electrode EL side moves upward, but the area of the facing portion remains unchanged. Even if the electrode ES is moved downward or in the depth direction or the front direction of the paper surface, the area of the facing portion on the electrode EL side does not change.

In short, when the contour of the electrode ES having the smaller area is projected onto the surface of the electrode EL having the larger area to form the orthogonal projection image, the projection image of the electrode ES is completely formed within the surface of the electrode EL. As long as the included state is maintained, the effective area of the capacitive element formed by both electrodes is equal to the area of the electrode ES and is always constant.

Therefore, if the relationship between the displacement electrode E2 and the fixed electrode E1 shown in FIG. 18 is the same as the relationship between the electrode ES and the electrode EL shown in FIG. 19, the displacement electrode E2 is affected by the external force. Even if it is displaced in the direction, as long as the displacement electrode E2 and the fixed electrode E1 are kept parallel to each other, the effective facing area of the pair of electrodes forming the capacitive element C is constant. This means that the change in the capacitance value of the capacitive element C occurs exclusively according to the distance between the displacement electrode E2 and the fixed electrode E1. In other words, the change in the capacitance value of the capacitive element C occurs only depending on the displacement of the displacement portion 63 in the direction along the normal line N, and the change in the direction orthogonal to the normal line N occurs. This means that it does not depend on displacement. This is useful for accurately detecting the applied external force based on the principle described above.

As described above, in the embodiment in which the capacitive element is used as the detection element, even when the displacement electrode E2 moves in parallel to the fixed electrode E1 as a result of the application of a predetermined external force to the detection ring 600, the capacitive element C is removed. It is preferable to set the area of one of the fixed electrode E1 and the displacement electrode E2 to be larger than the area of the other so that the effective facing area of the pair of electrodes does not change. Although FIG. 19 shows an example in which rectangular electrodes are used as the two electrodes EL and ES, the shapes of the displacement electrode E2 and the fixed electrode E1 used in the force sensor according to the present invention are arbitrary. However, for example, a circular electrode may be used.

<3-4. Specific detection method for each external force component>
Subsequently, in the force sensor using the basic structure shown in FIG. 16, the forces Fx, Fy, Fz in each coordinate axis direction and the moment Mx about each coordinate axis are applied to the force receiving body 100 in a state where the support substrate 300 is fixed. Let us consider the operation when My and Mz act. As illustrated in FIG. 18, the displacement electrode E2 is arranged on the lower surface of each detection section D (the lower surface of the displacement section 63), and the fixed electrode E1 is arranged on the upper surface of the supporting substrate 300 at the facing portion. A capacitive element C is formed by the pair of electrodes E1 and E2. Therefore, here, the capacitive elements formed for the four sets of detection units D1 to D4 will be referred to as capacitive elements C1 to C4, respectively, and the capacitance values of these capacitive elements C1 to C4 will be denoted by the same reference numerals C1 to C1. It is indicated by C4.

The table of FIG. 20 shows the amount of change (degree of increase or decrease) in the capacitance value of each of the capacitive elements C1 to C4 when external force Fx, Fy, Fz, Mx, My, Mz is applied to the force receiving body 100. Like In this table, “+” indicates that the capacitance value increases (the electrode spacing of the capacitive element C decreases), and “−” indicates that the capacitance value decreases (the electrode spacing of the capacitive element C increases). Yes). In addition, “++” indicates that the degree of increase in capacitance value is larger than that of “+”, and “(+)” indicates that the degree of increase of capacitance value is smaller than that of “+”. Show. Similarly, “−−” indicates that the degree of decrease in capacitance value is larger than that of “−”, and “(−)” indicates that the degree of decrease of capacitance value is smaller than that of “−”. Indicates that.

However, the absolute value of the increase or decrease of each capacitance value actually depends on the size and thickness of each part of the detection ring 600, particularly on the size and thickness of the plate-shaped pieces 61, 62, 63 forming the detection part D. Therefore, the difference between “(+)”, “+”, and “++” in the table shown in the present application and the difference between “(−)”, “−”, and “−−” are relative. It is a thing. In particular, the forces Fx, Fy, Fz (unit: N) and the moments Mx, My, Mz (unit: N·m) are different physical quantities and cannot be directly compared.

The table of FIG. 20 shows measured values when forces of the same magnitude are applied to the outer peripheral portion of the force receiving body 100 in respective directions (directions acting as external forces of Fx, Fy, Fz, Mx, My, and Mz). It was created based on. Therefore, the value of the moment is converted as a value obtained by multiplying the force applied to the outer peripheral portion of the force receiving body 100 by the radius of the outer peripheral portion of the force receiving body 100. The table of FIG. 20 shows “(+)” and “(−)” when the absolute value is less than 5 based on such a conversion value, and “when the absolute value is 5 or more and less than 50”. It is shown by "+" and "-", and when the absolute value is 50 or more, it is shown by "++" and "--".

The fact that the results shown in the table of FIG. 20 are obtained is obtained by detecting the detection ring 600 shown in FIG. 16 by referring to the modification of the detection ring 200 in the prior application force sensor shown in FIGS. It can be understood by recognizing what kind of stress acts on each position of the portions D1 to D4 and then considering the displacement direction of the displacement portion 63 shown in FIG. The detection ring 200 and the detection ring 600 are different from each other in the structure of the detection portions D1 to D4, but are both ring-shaped rings, and are fixed on the Y-axis at fixed points P1 and P2. The action points Q1 and Q2 of 1 are common in that they are deformed by the action of an external force. Therefore, the stress applied to the positions of the detection portions D1 to D4 of the detection ring 600 is the same as the stress applied to the corresponding positions of the detection ring 200 shown in FIGS.

For example, when the force +Fx in the positive direction of the X axis acts on the force receiver 100, the detection ring 200 deforms as shown in FIG. 4, and the extension force f2 is generated between the points P1-Q1 and between the points P2-Q1. Acts, and the compressive force f1 acts between points P1-Q2 and between points P2-Q2. Therefore, in the case of the detection ring 600 shown in FIG. 16, the extension force f2 acts on the detection portions D1 and D4, the displacement portion 63 moves upward as shown in FIG. 17(c), and the electrostatic capacitance value C1, C4 decreases. On the other hand, the compressive force f1 acts on the detection portions D2 and D3, the displacement portion 63 moves downward as shown in FIG. 17(b), and the electrostatic capacitance values C2 and C3 increase. Each column of the row of Fx in the table of FIG. 20 shows such a result.

Similarly, when the force +Fy in the positive direction of the Y-axis acts on the force receiver 100, the compressive force f1 acts between the points P1-Q1 and between the points P1-Q2, and between the points P2-Q1 and the point P2-. An extension force f2 acts between Q2. Therefore, in the case of the detection ring 600 shown in FIG. 16, the compression force f1 acts on the detection portions D1 and D2, and the electrostatic capacitance values C1 and C2 increase. On the other hand, the extension force f2 acts on the detection units D3 and D4, and the capacitance values C3 and C4 decrease. Each column of the Fy row in the table of FIG. 20 shows such a result.

When the force +Fz in the Z-axis positive direction acts on the force receiving body 100, the detection ring 200 deforms as shown in FIG. Therefore, in the case of the detection ring 600 shown in FIG. 16, the four detection units D1 to D4 all move upward (Z axis positive direction). Therefore, the electrode intervals of the four sets of capacitive elements C1 to C4 are all widened, and the capacitance values C1 to C4 are reduced. Each column of the row of Fz in the table of FIG. 20 shows such a result. Since the positions of the fixed points P1 and P2 do not change, the detectors D1 to D4 are slightly inclined with respect to the XY plane, and the pair of electrodes forming each of the capacitive elements C1 to C4 are not parallel. Therefore, the effective facing area of the pair of electrodes slightly varies, but the capacitance values C1 to C4 are mainly affected by the variation in the inter-electrode distance.

On the other hand, when the moment +My about the Y-axis is applied to the force receiving body 100, the detection ring 200 is deformed as shown in FIG. 6, the right half of the figure is displaced downward, and the left half of the figure is upward. Is displaced to. Therefore, in the case of the detection ring 600 shown in FIG. 16, the detection units D1 and D4 located in the right half of the figure are displaced downward, and the detection units D2 and D3 located in the left half of the diagram are displaced upward. Therefore, the electrode spacing of the capacitive elements C1 and C4 becomes small, and the electrostatic capacitance values C1 and C4 increase. In addition, the electrode spacing between the capacitive elements C2 and C3 increases, and the electrostatic capacitance values C2 and C3 decrease. Each column of the My row in the table of FIG. 20 shows such a result.

Similarly, when the moment +Mx about the X-axis is applied to the force receiver 100, in the case of the detection ring 600 shown in FIG. 16, the detection units D3 and D4 located in the lower half of the figure are displaced downward, The detectors D1 and D2 located in the upper half of the upper part are displaced upward. Therefore, the electrode spacing between the capacitive elements C3 and C4 becomes smaller, and the electrostatic capacitance values C3 and C4 increase. In addition, the electrode spacing between the capacitive elements C1 and C2 increases, and the capacitance values C1 and C2 decrease. Each column of the row of Mx in the table of FIG. 20 shows such a result.

Even when the moments +Mx and +My are applied, the detectors D1 to D4 are slightly tilted with respect to the XY plane, and therefore the pair of electrodes forming the capacitors C1 to C4 are not parallel to each other. Therefore, the effective facing area of the pair of electrodes slightly varies, but the capacitance values C1 to C4 are mainly affected by the variation in the inter-electrode distance.

Finally, when the moment +Mz about the Z-axis is applied to the force receiving body 100, the detection ring 200 is deformed as shown in FIG. 7, and the compression force is applied between the points P1 and Q1 and between the points P2 and Q2. f1 acts, and the extension force f2 acts between points P1-Q2 and between points P2-Q1. Therefore, in the case of the detection ring 600 shown in FIG. 16, the compression force f1 acts on the detection portions D1 and D3, and the electrostatic capacitance values C1 and C3 increase. On the other hand, the extension force f2 acts on the detection units D2 and D4, and the capacitance values C2 and C4 decrease. Each column of the row of Mz in the table of FIG. 20 shows such a result.

In the table of FIG. 20, each column of the row of Fx and the row of Fy is “(+)” or “(−)” when Fx and Fy act and when Fz and Mz act. This is because the amount of displacement generated in the displacement portion 63 of each of the detection units D1 to D4 is smaller than that in. On the other hand, each column of the row of Mx and the row of My is “++” or “−−” when Mx and My act, as shown in FIG. 6, the detection ring is greatly inclined, This is because the displacement electrode E2 is largely displaced.

The table of FIG. 20 shows the results when a positive force and a positive moment are applied. However, when a negative force and a negative moment are applied, “+” and “−” are given. The result will be reversed.

The force sensor according to the basic embodiment (first embodiment) of the present invention includes four sets of capacitive elements C1 to C4 (four sets of displacement electrodes and four sets of fixed electrodes) in the basic structure shown in FIG. ) And a detection circuit are added. This force sensor measures the displacement at a specific location by electrically detecting the change in the capacitance value of the capacitive elements C1 to C4 arranged in each of the detection units D1 to D4, and detects the force and moment acting. It has a function to detect the direction and size. Here, the principle of detection of forces and moments on each coordinate axis by the force sensor and an example of a specific detection circuit will be shown.

As described above, in this force sensor, when external force Fx, Fy, Fz, Mx, My, Mz is applied to the force receiving body 100, the capacitance values of the respective capacitive elements C1 to C4 are as shown in the table of FIG. It causes fluctuations as shown in. Here, since "(+)" and "(-)" have smaller variations than "+" and "-", they will be treated as approximately 0. Then, the table of FIG. 20 is approximately replaced with the table of FIG. Assuming the table of FIG. 21, the four-axis components Fz, Mx, My, Mz of the external force acting on the force receiving body 100 can be calculated by the arithmetic expression shown in FIG.

First, it can be understood that the force Fz in the Z-axis direction can be obtained by the calculation of Fz=−(C1+C2+C3+C4) by referring to each column of the row of Fz in the table of FIG. Moreover, it can be seen that the use of this arithmetic expression cancels each other even if there is an axial component other than Fz. For example, when the results in the respective columns of the rows of Mx, My, Mz are respectively substituted into the above-described arithmetic expression for calculation, the results of Fz=0 are obtained. Therefore, the value Fz obtained by the above arithmetic expression is a value indicating only the force component Fz in the Z-axis direction that does not include the other axis component. This is because the structures of the detection units D1 to D4 and the capacitive elements C1 to C4 have symmetry with respect to both the XZ plane and the YZ plane.

Next, regarding the moment Mx about the X-axis, it can be understood by referring to each column of the row of Mx in the table of FIG. 21 that it is obtained by the calculation of Mx=−C1−C2+C3+C4. Similarly, the moment My about the Y axis is obtained by the calculation of My=+C1-C2-C3+C4 by referring to each column of the row My in the table of FIG. 21, and the moment Mz about the Z axis is obtained. With reference to each column of the row of Mz in the table of FIG. 21, Mz=+C1-C2+C3-C4 is obtained. In any of the arithmetic expressions, the other axis components cancel each other out, so that only the components not including the other axis components are obtained.

After all, if the four arithmetic expressions shown in FIG. 22 are used, the values of the four-axis components Fz, Mx, My, and Mz can be detected without the interference of the other-axis components. Of course, the table of FIG. 21 is obtained by performing an approximation with the columns of “(+)” and “(−)” in the table of FIG. It is included as a detection error. However, as long as the force sensor is used for a purpose in which the error is within the allowable range, there will be no practical problem.

FIG. 23 is a circuit diagram showing an example of a detection circuit that outputs an electrical signal indicating four-axis components of force Fz and moments Mx, My, Mz based on the arithmetic expression shown in FIG. The capacitive elements C1 to C4 shown in this circuit diagram are the capacitive elements C1 to C4 provided in the detection units D1 to D4. Each of the capacitive elements C1 to C4 is composed of a fixed electrode E1 and a displacement electrode E2 (see FIG. 18). In this circuit, four sets of fixed electrodes E1 are connected to each other so as to have a common ground potential, and four sets of displacement electrodes E2 are electrically independent electrodes. Therefore, in the circuit diagram of FIG. 23, the fixed electrodes are indicated by the same reference numeral E1, and the displacement electrodes are indicated by the individual reference numerals E2(D1), E2(D2), E2(D3), E2(D4). It is indicated by. Conversely, four sets of displacement electrodes E2 may be connected to each other and the four sets of fixed electrodes E1 may be electrically independent electrodes.

The C/V conversion circuits 11 to 14 are circuits that respectively convert the capacitance values C1 to C4 of the capacitive elements C1 to C4 into voltage values V1 to V4, and the converted voltage values V1 to V4 are respectively It becomes a value corresponding to the electrostatic capacitance values C1 to C4. Each of the adder/subtractor calculators 15 to 18 has a function of performing a calculation based on the calculation formula shown in FIG. 22 and outputting the result to the output terminals T1 to T4. Thus, the voltage values corresponding to the four axis components Fz, Mx, My and Mz are output to the output terminals T1 to T4. Of course, a microprocessor may be used instead of the addition/subtraction arithmetic units 15 to 18 to perform arithmetic operations.

After all, if the capacitive element C as shown in FIG. 18 is added to each position of the four sets of detection units D1 to D4 of the basic structure shown in FIG. 16 and the detection circuit shown in FIG. It is possible to realize a force sensor that can detect the values of the axial components Fz, Mx, My, and Mz. Here, each of the four sets of capacitive elements (detection elements) includes a displacement electrode E2 formed on the lower surface of the detection ring 600 (lower surface of the displacement portion 63) and a fixed electrode E1 formed on the upper surface of the support substrate 300. , Which simplifies the manufacturing process.

The inter-electrode distance between the pair of electrodes (the fixed electrode E1 and the displacement electrode E2) forming each of the capacitive elements C1 to C4 is defined by the height dimension of the fixed members 510 and 520 shown in FIG. Accuracy can be easily secured. For this reason, a complicated work for adjusting the electrode interval becomes unnecessary, and high production efficiency can be secured even when commercial mass production is performed.

Of course, this force sensor cannot detect Fx and Fy, and, as described above, since the detection is performed based on the approximation table shown in FIG. 21, mixing of other axis components may occur. Become. However, it is sufficient if the four-axis components Fz, Mx, My, Mz or a part of them can be detected. If the error based on the above approximation is within an allowable range, this force sensor is industrially sufficiently used. It is possible. Note that a force sensor that can detect all of the six-axis components Fx, Fy, Fz, Mx, My, and Mz and a force sensor that can obtain a more accurate detection value will be described as another embodiment. This will be described in Section 5 onwards.

<<<<§4. Essential features of force sensor according to the present invention >>>
The force sensor according to the present invention is a force sensor that detects a force or a moment related to at least one of the forces in each coordinate axis direction and the moment around each coordinate axis in the XYZ three-dimensional orthogonal coordinate system. The force sensor according to the basic embodiment described in §3 is an example thereof, and has a function of detecting the four-axis components Fz, Mx, My, Mz. Here, the essential characteristics of the force sensor according to the present invention will be described with reference to the force sensor described in §3.

A force sensor according to the present invention includes a force-receiving body that receives a force or a moment to be detected, a detection ring having a structure in which at least a part of the elastic ring is deformed, and a support body that supports the detection ring. And has a function of detecting a force or a moment acting on the other of the force receiving body and the supporting body when a load is applied to the other. In the case of the basic embodiment described in §3, the support substrate 300 is used as a support, but the support does not necessarily have to be a substrate-like structure, and may be a member having an arbitrary shape. Further, the force receiving body 100 does not necessarily have to be an annular member, and may be a member having an arbitrary shape.

However, if the plate-shaped support substrate 300 is used as a support, the other members are arranged above the support substrate 300, the force receiving body 100 is an annular member, and the force receiving body 100 is arranged outside the detection ring 600, the entire structure is obtained. Since it is possible to realize a thin sensor, it is preferable to use the support substrate 300 as a support and the force receiving body 100 as an annular member in order to reduce the thickness.

The detection ring 600 is a component that plays the most important role in the present invention and has an annular structure extending along a predetermined basic annular path B. A detection point R is defined on the basic ring road B. In the case of the detection ring 600 shown in FIG. 13, four detection points R1 to R4 are defined on the basic ring road B as shown in FIG. As shown in FIG. 14, the detection ring 600 has detection parts D1 to D4 located at the respective detection points R1 to R4 and connecting parts L1 to L4 located on both sides of each detection part. ..

As shown in FIG. 16, the connecting members 410 and 420 connecting the force receiving body 100 to the positions of the action points Q1 and Q2 of the detection ring 600 and the positions of the fixing points P1 and P2 of the detection ring 600 are set to the support (support substrate 300). ), and fixing members 510 and 520 for fixing to (). Here, the respective action points Q1 and Q2 and the respective fixed points P1 and P2 are arranged at mutually different positions of the connecting portions L1 to L4.

When a force acts between the action points Q1 and Q2 and the fixed points P1 and P2, the detection units D1 to D4 have a structure in which at least a part thereof elastically deforms based on the action force. The detection unit D illustrated in FIG. 17 is composed of three plate-shaped pieces 61, 62, and 63, so that the entire member becomes a member that elastically deforms. However, for example, the displacement unit 63 has an increased thickness. A member that does not elastically deform may be used.

In the force sensor according to the present invention, the force receiving body 100 and the support body (support substrate 300) are further based on the detection element that detects the elastic deformation generated in the detection units D1 to D4 and the detection result of the detection element. A detection circuit is provided which outputs an electric signal indicating the force or moment acting on the other when one is loaded.

In the case of the basic embodiment described in §3, as shown in FIG. 18, the displacement electrode E2 fixed at a predetermined position of the detection section D and the position facing the displacement electrode E2 of the support (support substrate 300) are provided. The detection element is configured by the capacitive element C having the fixed electrode E1 that is fixed. Here, the displacement electrode E2 is located at a position (specifically, in the case of the example shown in FIG. 18, the lower surface of the displacement portion 63) that is displaced with respect to the fixed electrode E1 based on the elastic deformation generated in the detection unit D. It is arranged. Then, as illustrated in FIG. 23, the detection circuit outputs an electric signal indicating the applied force or moment based on the change in the capacitance value of each of the capacitive elements C1 to C4.

In the basic embodiment described in §3, for the sake of convenience, the force or moment acting on the force receiving body 100 is detected in the state where the supporting substrate 300 (supporting body) is fixed. Even if the force or moment acting on the support substrate 300 (support) is detected while the force receiving body 100 is fixed, the principle of operation is the same according to the law of action and reaction.

In the present application, for convenience, one is referred to as a support (support substrate 300) and the other is referred to as a force receiving body 100, and only a detection operation for detecting a force or a moment applied to the force receiving body with the support fixed is described. Even if the support body and the force receiving body are exchanged, there is no difference in detection principle. Therefore, for example, in the basic structure shown in FIG. 16, even if the ring-shaped member 100 is interpreted as a support and the substrate-shaped member 300 is interpreted as a force receiving body, there is no difference in the operating principle of the force sensor. (In this case, points P1 and P2 are acting points and points Q1 and Q2 are fixed points).

In the example shown in FIG. 16, the detection ring 600 extends along the basic annular path B located on the XY plane with the Z axis as the central axis when the XY plane is taken as the horizontal plane and the Z axis is taken as a vertically upward axis. It has an annular structure. The support body is composed of a support substrate 300 arranged below the detection ring 600 at a predetermined interval. If such an arrangement is adopted, the displacement electrodes E2 are fixed to the lower surfaces of the detection units D1 to D4, and the fixed electrodes E1 are fixed to the upper surface of the support substrate 300, thereby configuring the capacitive elements C1 to C4. Therefore, the work of adjusting the electrode interval becomes easy, and the production efficiency can be improved.

In addition, in this basic embodiment, as shown in FIG. 17, the detection unit D includes a first deformation unit 61 and a second deformation unit 62 that elastically deform due to the action of a force or moment that is a detection target; The first deformation portion 61 and the second deformation portion 62 have a displacement portion 63 that is displaced by elastic deformation. Here, the outer end of the first deformable portion 61 is connected to the connecting portion L adjacent thereto, and the inner end thereof is connected to the displacement portion 63. The outer end of the second deformable portion 62 is connected to the connecting portion L adjacent to the second deformable portion 62, and the inner end thereof is connected to the displacement portion 63. Therefore, the lower surface of the displacement portion 63 becomes a surface parallel to the upper surface of the support substrate 300, and the displacement electrode E2 is formed on the lower surface of the displacement portion 63 as in the example shown in FIG. By forming the fixed substrate E1 on the upper surface, the capacitive element C including a pair of parallel electrodes can be formed.

Since the detection ring 600 shown in FIG. 13 is provided with four sets of detection units D1 to D4, a total of four sets of capacitive elements C1 to C4 (detection elements) are formed as described above. .. However, in implementing the present invention, the number n of the detection units D is not necessarily limited to four sets, and it is sufficient if at least one set of the detection units D is provided.

However, since the axis component to be detected is limited and sufficient detection accuracy cannot be obtained with only one set of the detection units D, the number n of the detection units D (the number n of the detection points R) is practically used. It is preferable to set n≧2 and to provide a plurality of detection units D. In other words, a plurality of n (n≧2) detection points R1, R2,..., Rn are defined on the basic ring road B, and a detection unit is arranged at each detection point to provide n detection points. , Dn and n connecting portions L1, L2,..., Ln are alternately arranged along the basic annular path B to form a detection ring. Is preferred.

Moreover, in practice, the number n of the detection units D is set to an even number, an even number n of detection points is defined on the basic loop road B, and the detection units are arranged at the respective detection points to detect an even number n of detections. It is preferable that the detection ring is configured by alternately arranging the parts and the even-numbered n connecting parts along the basic annular path B. By providing an even number n of detection units, it is possible to configure a basic structure unit having symmetry with respect to both the XZ plane and the YZ plane in the XYZ three-dimensional Cartesian coordinate system. This is because the advantages of eliminating the interference of the axial components and simplifying the arithmetic processing performed by the detection circuit can be obtained.

In this case, when numbers are given in order from the predetermined starting point along the basic annular road B to the even-numbered n connecting portions, the action points Q1, Q2,... Are arranged in the odd-numbered connecting portions. , Fixed points P1, P2,... Are preferably arranged at even-numbered connecting portions. Then, in a state where each fixed point P is fixed, the external force acting on each action point Q can be efficiently transmitted to each detection unit D, and an efficient detection operation can be realized.

For example, when the number n of the detection points R is set to n=2, the first connecting portion L1, the first detecting portion D1, the second connecting portion L2, and the second detecting portion along the basic ring road B are detected. The detection ring can be configured by arranging the parts D2 in this order. In this case, the action point Q1 may be arranged on the first connecting portion L1 and the fixed point P1 may be arranged on the second connecting portion L2.

The force sensor according to the basic embodiment described in §3 is a more practical example in which the number n of detection points R is set to n=4. That is, as shown in FIG. 15, in the XY plane, the V axis is defined as a coordinate axis obtained by rotating the X axis counterclockwise by 45° about the origin O, and the Y axis is rotated counterclockwise about the origin O by 45 degrees. When the W axis is defined as the rotated coordinate axis, the first detection point R1 is on the positive V axis, the second detection point R2 is on the positive W axis, and the third detection point R3 is on the negative V axis. On the axis, the fourth detection point R4 is arranged on the negative W axis.

As a result, as shown in FIG. 14, the four sets of detection units D1 to D4 are arranged on the V axis or the W axis. Then, along the basic ring road B, in the counterclockwise direction, the first connecting portion L1, the first detecting portion D1, the second connecting portion L2, the second detecting portion D2, the third connecting portion L3, and the third connecting portion L3. The detection ring 600 is configured by arranging the three detection parts D3, the fourth connection part L4, and the fourth detection part D4 in this order.

Further, as shown in FIG. 15, the first point of action Q1 is arranged on the positive X-axis (first connecting portion L1), and the second point of action Q2 is on the negative X-axis (third connecting portion). L3), the first fixed point P1 is located on the positive Y axis (second connecting portion L2), and the second fixed point P2 is on the negative Y axis (fourth connecting portion L4). It is located in. In other words, the action points Q1 and Q2 are arranged at odd-numbered connecting portions, and the fixed points P1 and P2 are arranged at even-numbered connecting portions.

In the basic structure shown in FIG. 16, the first connecting member 410 that connects the position of the first action point Q1 of the detection ring 600 to the force receiving body 100 and the second action point Q2 of the detection ring 600. A second connecting member 420 that connects the position to the force receiving body 100, a first fixing member 510 that fixes the position of the first fixing point P1 of the detection ring 600 to the support substrate 300, and a second connecting member of the detection ring 600. And a second fixing member 520 for fixing the position of the fixing point P2 to the supporting substrate 300. In such a basic structure part, the stress generated based on the external force applied to the force receiving body 100 can be efficiently transmitted to the four sets of detection parts D1 to D4 in the state where the support substrate 300 is fixed.

As shown in FIG. 18, a capacitive element C is formed in each detection unit D, in which the increase and decrease of the capacitance value is reversed when the compressive stress acts along the basic annular path B and when the tensile stress acts. Has been done.

Therefore, the capacitance value of the first capacitive element C1 having the displacement electrode E2 (D1) fixed to the first detection portion D1 located at the first detection point R1 is set to C1, and the second detection point R2 is set to C1. The capacitance value of the second capacitive element C2 having the displacement electrode E2 (D2) fixed to the second detection section D2 located is C2, and the third detection section D3 located at the third detection point R3. The capacitance value of the third capacitive element C3 having the fixed displacement electrode E2 (D3) is C3, and the displacement electrode E2 (D4) fixed to the fourth detection portion D4 located at the fourth detection point R4. Assuming that the capacitance value of the fourth capacitive element C4 having C4 is C4, as shown in FIG.
Fz=-(C1+C2+C3+C4)
Mx=-C1-C2+C3+C4
My=+C1-C2-C3+C4
Mz=+C1-C2+C3-C4
By performing an operation based on the following equation, the force Fz acting in the Z-axis direction, the moment Mx acting around the X axis, the moment My acting around the Y axis, and the moment Mz acting around the Z axis are calculated. be able to.

As described above, for example, the circuit shown in FIG. 23 can be used as the detection circuit that outputs the electric signals corresponding to the detection values Fz, Mx, My, and Mz based on such calculation. ..

When a capacitive element is used as the detection element, it is preferable to perform a calculation for obtaining a difference in electrostatic capacitance value between the plurality of capacitive elements and output the detected value. For example, among the four arithmetic expressions in the above example, only the arithmetic expression regarding Fz is an arithmetic expression for obtaining the sum of four electrostatic capacitance values C1 to C4, but the other arithmetic expressions include those of a plurality of capacitive elements. It is a difference calculation formula for obtaining a difference in electrostatic capacitance value. Such difference calculation is useful for removing errors that occur in the manufacturing process (for example, dimensional errors of parts and mounting positions) and errors that occur in the usage environment (for example, errors caused by expansion of members due to temperature). Is effective.

For example, in the case of the embodiment shown in FIG. 16, the electrode intervals of the four sets of capacitive elements C1 to C4 are defined by the dimension of the pair of fixing members 510 and 520 in the height direction. Even if an error occurs in the dimension of the fixing members 510 and 520 in the height direction due to a dimensional error or a temperature environment, the dimensional error can be canceled by the difference calculation, so that an accurate detection value including no error is output. It becomes possible to do.

Generally speaking, regarding the force or moment about a specific axis to be detected, some of the plurality of n detection units behave as the first attribute detection unit, and the other part of the plurality of n detection units have the second attribute. Will behave as a detection unit of. Here, the detection unit of the first attribute means that, when a positive component about a specific axis acts, the displacement unit 63 is displaced in a direction approaching the support substrate 300, and a negative component about the specific axis is detected. The displacement portion 63 is a detection portion having a property of being displaced in a direction away from the support substrate 300 when it acts. On the other hand, when the positive component about a specific axis acts, the displacement unit 63 is displaced in the direction away from the support substrate 300, and the negative component about the specific axis is the second attribute detecting unit. The displacement portion 63 is a detection portion having a property of being displaced in a direction approaching the support substrate 300 when the displacement portion 63 acts.

Then, when detecting the component about the specific axis, the first attribute displacement electrode E2 fixed to the displacement portion 63 of the detection unit of the first attribute and the first attribute fixed to a position where the support substrate 300 faces each other. A capacitive element formed by the fixed electrode E1 is referred to as a first attribute capacitive element, and is disposed at a position where the second attribute displacement electrode E2 fixed to the displacement section 63 of the second attribute detection section and the support substrate 300 face each other. If the capacitive element formed by the fixed second attribute fixed electrode E1 is referred to as the second attribute capacitive element, the capacitance value of the first attribute capacitive element and the second attribute capacitive element of the second attribute capacitive element are detected by the detection circuit. An electric signal corresponding to the difference between the capacitance value and the electrostatic capacitance value may be obtained and output as an electric signal indicating the detection component of the force or moment to be detected about the specific axis.

Of course, whether a certain specific capacitive element behaves as the first attribute capacitive element or the second attribute capacitive element depends on the specific axial component acting, so the six axial components Fx, Fy. , Fz, Mx, My, and Mz act, the attributes are defined respectively. Specifically, regarding the specific row of the table shown in FIG. 21, the capacitive element in which “+” or “++” is described is the first attribute capacitive element as far as the specific axial component corresponding to the row is concerned. Therefore, the capacitive element with “−” or “−−” described is the second attribute capacitive element as far as the specific axial component corresponding to the row is concerned.

The addition/subtraction calculators 16, 17, and 18 shown in FIG. 23 take into account such attributes, and the capacitance value of the first attribute capacitive element and the capacitance value of the second attribute capacitive element regarding the specific axis component. It means that the difference calculation for obtaining the difference between and is performed. Note that the addition/subtraction calculator 15 performs only the calculation for obtaining the sum, and therefore the error canceling function based on the above difference calculation does not work.

<<<<§5. Embodiment using 8 sets of detectors >>>
Subsequently, an embodiment (second embodiment) in which the number n of detection points R is set to n=8 and a total of eight detection units are used will be described here. In the basic embodiment (first embodiment) described in §3, the number n of detection points R is set to n=4, and a total of four sets of detection units D1 to D4 are used. Since Fy cannot be sufficiently detected, the example in which the four-axis components Fz, Mx, My, and Mz are detected using the approximation table shown in FIG. 21 has been described. In the embodiment using the eight detection units described here, the manufacturing cost increases as the number of the detection units increases, but the six-axis components Fx, Fy, Fz, Mx, My, and Mz are practically used. It is possible to perform the detection operation with sufficient accuracy.

FIG. 24 is a bottom view of the detection ring 700 used in the force sensor according to the embodiment using the eight pairs of detection units. As can be seen by comparing the detection ring 600 shown in FIG. 13(c) and the detection ring 700 shown in FIG. 24, the only substantial difference between them is the number of detection portions D. FIG. 24 is a bottom view of the detection ring 700 looking up from below, and eight sets of detection units D11 to D18 are arranged in a clockwise order. The structures of the detection units D11 to D18 are similar to the structure of the detection unit D shown in FIG. FIG. 24 shows an example in which the detection unit D18 is configured by three plate-shaped pieces, that is, a first deformable portion 71, a second deformable portion 72, and a displacement portion 73. The other detectors D11 to D17 also have the same structure.

FIG. 25 is a top view showing the region distribution of the detection ring 700 shown in FIG. 24 (mesh-like hatching is for showing the regions of the detection portions D11 to D18, not for showing the cross section). As illustrated, the detection ring 700 has a structure in which eight sets of detection units D11 to D18 are connected by eight sets of connection units L11 to L18. The detecting portions D11 to D18 are formed by three plate-shaped pieces, while the connecting portions L11 to L18 are formed by thick members, and when an external force acts on the detecting ring 700, the external force is applied. The elastic deformation of the detection ring 700 based on (1) is concentrated on the detection portions D11 to D18.

Since FIG. 25 is a top view, the first connecting portion L11, the first detecting portion D11, the second connecting portion L12, the first connecting portion L11, and the second connecting portion L12 are rotated counterclockwise along the basic ring road B shown by the thick dashed line in the drawing. 2 detection part D12, 3rd connection part L13, 3rd detection part D13, 4th connection part L14, 4th detection part D14, 5th connection part L15, 5th detection part D15, 6th By arranging the connecting portion L16, the sixth detecting portion D16, the seventh connecting portion L17, the seventh detecting portion D17, the eighth connecting portion L18, and the eighth detecting portion D18 in this order, 700 is configured.

Also in this figure, the V axis is defined as a coordinate axis obtained by rotating the X axis counterclockwise about the origin O by 45° on the XY plane, and the Y axis is rotated counterclockwise about the origin O by 45°. The W axis is defined as the coordinate axis. <I>, <II>, <III>, and <IV> in the figure show the first to fourth quadrants in the XY two-dimensional coordinate system. The eight detection units D11 to D18 are arranged in two sets in each quadrant.

FIG. 26 is a plan view showing the basic loop road B defined on the XY plane and the points defined on the basic loop road B in the detection ring 700 shown in FIG. The basic annular path B shown by a thick dashed line in the figure is a circle centered on the origin O arranged on the XY plane, and the detection ring 700 is an annular structure extending along the basic annular path B. In the figure, the positions of the inner contour line and the outer contour line of the detection ring 700 are indicated by solid lines. In the case of the illustrated embodiment, the basic annular path B is a circle on the XY plane passing through the intermediate position between the inner contour line and the outer contour line of the detection ring 700, and the annular thick portion of the detection ring 700 (the connecting portion L11). ~L18) becomes the center line.

Eight sets of detection points R11 to R18 are arranged on this basic ring road B at equal intervals. As in the example shown in FIG. 26, to define eight detection points R11 to R18 at equal intervals on the basic circular road B formed by a circle, in the XY plane, the origin O is set as the starting point and the X-axis positive direction is set. Is defined as an azimuth vector Vec(θ) that forms an angle θ counterclockwise with respect to the azimuth vector Vec(π/8+(i−1). )·Π/4) and the basic ring road B may be arranged at the intersection. For example, the first detection point R11 shown in FIG. 26 is set to θ=π/8, and the azimuth vector Vec(θ) forming an angle θ counterclockwise with respect to the positive direction of the X-axis and the basic loop road B. It is located at the intersection point.

In the figure, the VX axis is located at an intermediate position between the X axis and the V axis, the VY axis is located at an intermediate position between the V axis and the Y axis, the WY axis is located at an intermediate position between the Y axis and the W axis, and the X axis and the W axis are located at the intermediate position. The WX axis is defined at the intermediate position. After all, the eight detection points R11 to R18 are arranged in the positive and negative regions of the VX axis, VY axis, WY axis, and WX axis. These detection points R11 to R18 indicate the arrangement of the detection units D11 to D18, respectively, and as shown as a mesh-shaped hatched area in FIG. 25, eight detection units D11 to D18 each detect eight sets of detection units. It is arranged at the positions of points R11 to R18.

In the detection ring 600 having four sets of detection parts described in §3, two sets of fixed points P1 and P2 and two sets of action points Q1 and Q2 are defined, but there are eight sets of detection parts shown here. In the detection ring 700, as shown in FIG. 26, four sets of fixed points P11 to P14 (black circles) and four sets of action points Q11 to Q14 (white circles) are defined. Of course, the four sets of fixed points P11 to P14 are fixed to the support substrate 300, and the four sets of action points Q11 to Q14 are points to which the force from the force receiving body 100 acts.

As shown in FIG. 26, the first action point Q11 is on the positive X axis, the second action point Q12 is on the positive Y axis, the third action point Q13 is on the negative X axis, and the fourth action point. Q14 is on the negative Y-axis, the first fixed point P11 is on the positive V-axis, the second fixed point P12 is on the positive W-axis, the third fixed point P13 is on the negative V-axis, and the fourth fixed point P13 is on the negative V-axis. The fixed point P14 is arranged on the negative W axis. Therefore, in the force sensor using this detection ring 700, the force or moment acting on the four points Q11 to Q14 on the X-axis and the Y-axis is fixed while the four points P11 to P14 on the V-axis and the W-axis are fixed. Is detected based on the elastic deformation of the eight sets of detection units D11 to D18 arranged at the detection points R11 to R18 on the VX axis, VY axis, WY axis, and WX axis.

Also in this embodiment, the fixed points P11 to P14 and the action points Q11 to Q14 are alternately arranged along the basic annular road B. Such an alternating arrangement is important for effectively deforming the detection ring 700 when an external force to be detected acts. Further, the eight sets of detection points R11 to R18 are arranged between the fixed point and the action point which are adjacent to each other. Such an arrangement is also important for causing effective displacement of the detection units D11 to D18 when an external force to be detected acts.

As can be seen by comparing FIG. 25 and FIG. 26, the first action point Q11 is arranged at the first connecting portion L11, the first fixed point P11 is arranged at the second connecting portion L12, and Point of action Q12 is disposed on the third connecting portion L13, the second fixed point P12 is disposed on the fourth connecting portion L14, the third operating point Q13 is disposed on the fifth connecting portion L15, The third fixed point P13 is arranged in the sixth connecting portion L16, the fourth action point Q14 is arranged in the seventh connecting portion L17, and the fourth fixed point P14 is arranged in the eighth connecting portion L18. There is.

Here, the positions of the four sets of fixed points P11 to P14 of the detection ring 700 are fixed to the support substrate 300 by a fixing member. In FIG. 24, the connecting positions of the fixing members 560, 570, 580, 590 for fixing the positions of these fixing points P11 to P14 are indicated by broken lines. On the other hand, the positions of the four sets of action points Q11 to Q14 shown by white circles in FIG. 24 are connected to the force receiving body 100 by the connecting member.

FIG. 27 is a top view of the basic structure part of the force sensor according to the embodiment using eight sets of detection parts. This basic structure portion includes a force receiving body 100, a detection ring 700, and a support substrate 300. Although not shown in this top view, the support substrate 300 is a disk-shaped member having the same outer diameter as the force receiving body 100, and is disposed below the force receiving body 100 and the detection ring 700. .. The force receiving body 100 is an annular member similar to the embodiment shown in FIG. 16, and is arranged so as to surround the outside of the detection ring 700. The support substrate 300 is a disk-shaped member as in the embodiment shown in FIG. As described above, since the force receiving body 100 and the supporting substrate 300 shown in FIG. 27 are essentially the same as the force receiving body and the supporting substrate in the embodiment shown in FIG. 16, they are denoted by the same reference numerals.

The main difference between the basic structure part shown in FIG. 16 and the basic structure part shown in FIG. 27 is that the former uses a detection ring 600 having four sets of detection parts D1 to D4, whereas the latter has the same structure. , A detection ring 700 having eight sets of detection units D11 to D18 is used. Also, the difference accompanying this is that in the former, two sets of connecting members 410, 420 and two sets of fixing members 510, 520 are provided, whereas in the latter, four sets of connecting members 460. , 470, 480, 490 and four sets of fixing members 560, 570, 580, 590 are provided.

That is, the outer peripheral surface of the detection ring 700 near the first action point Q11 is connected to the inner peripheral surface of the force receiving body 100 by the first connecting member 460 arranged along the positive region of the X axis. The outer peripheral surface of the detection ring 700 in the vicinity of the second point of action Q12 is connected to the inner peripheral surface of the force receiving body 100 by the second connecting member 470 arranged along the positive region of the Y axis. There is. Similarly, the outer peripheral surface of the detection ring 700 near the third point of action Q13 is connected to the inner peripheral surface of the force receiving body 100 by the third connecting member 480 arranged along the negative region of the X axis. The outer peripheral surface of the detection ring 700 in the vicinity of the fourth point of action Q14 is connected to the inner peripheral surface of the force receiving body 100 by the fourth connecting member 490 arranged along the negative region of the Y axis. ing.

On the other hand, the lower surface of the detection ring 700 at the position of the first fixing point P11 (the position of the V-axis positive region) is fixed to the upper surface of the support substrate 300 by the first fixing member 560, and the second fixing of the detection ring 700. The lower surface at the position of the point P12 (the position of the W axis positive region) is fixed to the upper surface of the support substrate 300 by the second fixing member 570. Similarly, the lower surface of the detection ring 700 at the position of the third fixed point P13 (the position of the V axis negative region) is fixed to the upper surface of the support substrate 300 by the third fixing member 580, and the fourth surface of the detection ring 700 is fixed. The lower surface of the position of the fixed point P14 (the position of the W-axis negative region) is fixed to the upper surface of the support substrate 300 by the fourth fixing member 590.

The force sensor according to the second embodiment of the present invention is configured by adding a capacitive element and a detection circuit to the basic structure shown in FIG. Here, the capacitive element is a displacement electrode E2 formed on the lower surface of each displacement portion 73 of the eight pairs of detection portions D11 to D18 shown in FIG. 24, and a fixed electrode E1 formed on the upper surface of the support substrate 300 at an opposing position. And formed by. The detailed structure of such a capacitive element C is as already described in Section 3 with reference to FIG. According to the structure, a capacitive element is formed in which the increase and decrease in the capacitance value is reversed when the compressive stress acts along the basic annular path B and when the tensile stress acts. Here, the capacitive elements formed for the eight sets of detection units D11 to D18 are referred to as capacitive elements C11 to C18, respectively, and the electrostatic capacitance values of these capacitive elements C11 to C18 are denoted by the same reference numerals C11 to C18. I will show you.

Then, in the state where the support substrate 300 is fixed, the variation amount (increase/decrease) of the capacitance value of each of the capacitive elements C11 to C18 when the external force Fx, Fy, Fz, Mx, My, Mz is applied to the force receiving body 100. 28) is as shown in the table of FIG. Also in this table, “+” indicates that the capacitance value increases (the electrode spacing of the capacitive element C decreases), and “−” indicates that the capacitance value decreases (the electrode spacing of the capacitive element C decreases). Increase). In addition, “++” indicates that the degree of increase in capacitance value is larger than that of “+”, and “(+)” indicates that the degree of increase of capacitance value is smaller than that of “+”. Show. Similarly, “−−” indicates that the degree of decrease in capacitance value is larger than that of “−”, and “(−)” indicates that the degree of decrease of capacitance value is smaller than that of “−”. Indicates that.

Here, a detailed description of the reason why the result shown in the table of FIG. 28 is obtained is omitted, but in the state where the positions of the four fixed points P11 to P14 (black circles) shown in FIG. 27 are fixed, four sets are fixed. Considering the deformation mode of the detection ring 700 when the external force in the predetermined direction acts on the positions of the action points Q11 to Q14 (white circles), the displacement electrodes E2 of the detection units D11 to D18 are displaced. It will be easy to understand if you examine it.

In the table of FIG. 28, the result of the row of Fx and the row of Fy is “(+)” or “(−)” (that is, the degree of increase/decrease is small), as shown in FIG. 27. This is because the arrangement of the detection units D11 to D18 is deviated from the X axis and the Y axis, and thus the displacement electrode E2 is not largely displaced by the action of the forces Fx and Fy. On the other hand, the result of the row of Mx and the row of My is "++" or "--" (that is, the degree of increase/decrease is large), as shown in FIG. This is because, when acting, the detection ring is greatly inclined and the displacement electrode E2 is largely displaced.

The table of FIG. 28 shows the result when a positive force and a positive moment are applied, but “+” and “−” are given when a negative force and a negative moment are applied. The result will be reversed. Assuming the results shown in the table of FIG. 28, the 6-axis components Fx, Fy, Fz, Mx, My, Mz of the external force acting on the force receiving body 100 can be calculated by the arithmetic expression shown in FIG. it can.

First, the force Fx in the X-axis direction is obtained by the calculation of Fx=−C11+C12−C13+C14+C15−C16+C17−C18 by referring to each column of the row of Fx in the table of FIG. Similarly, the force Fy in the Y-axis direction is obtained by the calculation of Fy=+C11-C12-C13+C14-C15+C16+C17-C18 by referring to each column of the Fy row in the table of FIG. Then, the force Fz in the Z-axis direction is obtained by the calculation of Fz=-(C11+C12+C13+C14+C15+C16+C17+C18) by referring to each column of the Fz row of the table in FIG.

On the other hand, the moment Mx about the X axis can be obtained by the calculation of Mx=−C11−C12−C13−C14+C15+C16+C17+C18 by referring to each column of the row of Mx in the table of FIG. Similarly, the moment My about the Y axis can be obtained by the calculation of My=+C11+C12-C13-C14-C15-C16+C17+C18 by referring to each column of the row My of the table in FIG. Then, the moment Mz about the Z-axis is obtained by the calculation of Mz=+C11-C12+C13-C14+C15-C16+C17-C18 by referring to each column of the row of Mz in the table of FIG.

The basic structure shown in FIG. 27 has symmetry with respect to both the XZ plane and the YZ plane, and further has symmetry with respect to the VZ plane and the WZ plane. For this reason, if the respective arithmetic expressions shown in FIG. 29 are used, the other-axis components are almost canceled out, so that only the components not including the other-axis components are obtained. Strictly speaking, however, in the table of FIG. 28, the absolute values of the variations indicated by (+) and (−), the absolute values of the variations indicated by + and −, and the absolute values of ++ and −− are shown. The absolute value of the fluctuation amount does not completely match. For this reason, it is difficult to completely eliminate the interference of the other axis components, but in practical use, it can be suppressed to a level at which there is no problem. If necessary, it is also possible to perform a correction using a microcomputer or the like to remove the mixed other axis component. After all, if a detection circuit (not shown) that performs the calculation based on the calculation formula shown in FIG. 29 is prepared, the voltage values corresponding to the 6-axis components Fx, Fy, Fz, Mx, My, and Mz are used as electric signals. Can be output.

Note that the arithmetic expressions shown in FIG. 29 are calculations that use all of the eight sets of electrostatic capacitance values C11 to C18, but the arithmetic expressions do not necessarily use all the electrostatic capacitance values. There is no need, and only a part of it may be used.

For example, if only four sets of the eight sets of capacitance values C11 to C18 are used, the force Fx is calculated by the formula Fx=−C11+C12+C17−C18 or Fx=+C12−C13−C16+C17. It is possible to calculate the force Fy by an arithmetic expression Fy=+C11-C12-C13+C14 or Fy=-C15+C16+C17-C18, and the force Fz is Fz=-(C11+C14+C15+C18), or It is possible to obtain by the arithmetic expression Fz=-(C12+C13+C16+C17).

Similarly, the moment Mx can be obtained by an arithmetic expression Mx=-C11-C12+C17+C18 or Mx=-C13-C14+C15+C16, and the moment My is My=+C11+C12-C13-C14 or My=-. It is possible to obtain the calculation formula C15-C16+C17+C18, and the moment Mz is calculated by the calculation formula Mz=+C11-C12+C15-C16 or Mz=+C13-C14+C17-C18 or Mz=+C11-C14+C15-C18. It is possible.

FIG. 30 is a diagram showing a variation of such an arithmetic expression. 29 is an arithmetic expression that uses all of the eight sets of capacitance values C11 to C18, the variation shown in FIG. 30 has eight sets of capacitance values C11 to C18. It suffices to perform an operation using only four of these. Theoretically, a more accurate detection value can be obtained by performing an operation using all of the eight sets of electrostatic capacitance values C11 to C18, but in reality, each of the arithmetic expressions shown in FIG. By performing the calculation based on, it is possible to obtain the detection result with sufficient accuracy in practical use. Therefore, in order to reduce the calculation load of the detection circuit as much as possible, the variation shown in FIG. 30 may be adopted.

<<<<§6. Embodiment in which auxiliary connection member is added >>>
Here, an embodiment (third embodiment) in which an auxiliary connecting member is added will be described. In §3, regarding the force sensor according to the basic embodiment (first embodiment), when an external force of 6 axis components Fx, Fy, Fz, Mx, My, and Mz is applied, four sets of electrostatic charges are applied. Regarding the capacitance values C1 to C4, it has been described that the capacitance value varies as shown in the table of FIG. In this table, “++” and “−−” have a larger degree of increase in capacitance value than “+” and “−”, and “(+)” and “(−)” are “+”. It is shown that the degree of increase of the capacitance value is smaller than that of “” and “−”.

As described above, the magnitudes of fluctuations that occur in the four sets of capacitance values C1 to C4 differ depending on the external force component that acts, and thus the detection sensitivities of the respective axis components differ. Therefore, for example, even if the four-axis components Fz, Mx, My, Mz are detected based on the arithmetic expression shown in FIG. 22, the sensitivity of the detected values Mx, My is considerably higher than the sensitivity of the detected values Fz, Mz. Become. On the other hand, with respect to Fx and Fy, since the detection sensitivity is considerably low, in practice, as shown in the approximation table of FIG. 21, the variation amount must be set to 0, and the detection value cannot be obtained.

Of course, the detection sensitivity can be adjusted by changing the size of each part of the detection ring 600. For example, the thickness of the first deformable portion 61 and the second deformable portion 62 forming the detecting portion D can be reduced to reduce elasticity. If it is easily deformed, the detection sensitivity can be increased. However, although such a dimensional change is effective for adjusting the detection sensitivity of the force sensor as a whole, it cannot correct the difference in the detection sensitivity of each axis component. In providing a force sensor capable of detecting multi-axis components, it is not preferable that the detection sensitivities differ. Here, a method for correcting such a difference in detection sensitivity will be described.

In the force sensor described above, as a general tendency, the detection sensitivities of the components Mx and My are higher than the detection sensitivities of the other components. This is because the basic structure used in the present invention has a structure that is relatively easily deformed when a moment My about the Y axis acts, as shown in FIG. 6, for example. Similarly, when the moment Mx about the X axis acts, the deformation is likely to occur.

FIG. 31 is a bottom view (upper diagram) of the basic structure portion of the force sensor according to the third embodiment in which a difference in detection sensitivity is corrected in view of such structural features (upper diagram) and FIG. FIG. 4 is a side sectional view (lower diagram) taken along the XZ plane. In addition, in the bottom view shown in the upper stage, a state in which the support substrate 300 is removed is shown for convenience.

The difference between the basic structure portion according to the first embodiment shown in FIG. 16 and the basic structure portion according to the third embodiment shown in FIG. 31 is that in the latter case, auxiliary connection members 531 and 532 are added. Only. As shown in the lower side sectional view, the auxiliary connection member 531 is a columnar member arranged at a position where the connection reference line A1 passing through the point of action Q1 and parallel to the Z axis is the central axis, The upper end is connected to the lower surface of the detection ring 600, and the lower end is connected to the upper surface of the support substrate 300. Similarly, the auxiliary connection member 532 is a cylindrical member arranged at a position where the connection reference line A2 passing through the point of action Q2 and parallel to the Z axis is the central axis, and the upper end thereof is connected to the lower surface of the detection ring 600. The lower end is connected to the upper surface of the support substrate 300.

The detection ring 600 and the support substrate 300 are originally connected by a pair of fixing members 510 and 520. However, in the third embodiment shown here, the auxiliary connecting member 531 and 532 will be added. Here, the fixing members 510 and 520 are connected to the positions of the fixing points P1 and P2, while the auxiliary connecting members 531 and 532 are connected to the positions of the action points Q1 and Q2. The pair of auxiliary connection members 531 and 532 have a function of suppressing the displacement of the detection ring 600 that occurs when the moment My or Mx acts on the force receiving body 100.

FIG. 6 shows a deformation mode of the detection ring 200 when the moment My acts, but if the auxiliary connection members 531 and 532 are added to the positions of the action points Q1 and Q2, such deformation is suppressed. You can easily understand what is done. In this way, the auxiliary connection members 531 and 532 have a function of suppressing the deformation when the moment My acts, and further have a function of suppressing the deformation when the moment Mx acts. Of course, it also has a function of suppressing the deformation when the moment Mz and the forces Fx, Fy, and Fz act.

In short, the auxiliary connection members 531 and 532 function as “replacement bars” for keeping the distance between the detection ring 600 and the support substrate 300 constant at the positions of the connection reference lines A1 and A2. It should be noted that even if only one of the auxiliary connecting members 531 and 532 is provided, a certain effect can be obtained, but in practice it is preferable to provide both of them.

According to an experiment conducted by the inventor of the present application, the displacement suppressing effect of the auxiliary connecting members 531 and 532 is most prominent with respect to the moment My and is also prominent to some extent with respect to the moment Mx, but with respect to the forces Fx and Fy. Are few. This means that when the forces Fx and Fy are applied to the force receiver 100, the auxiliary connection members 531 and 532 are inclined with respect to the connection reference lines A1 and A2, but the auxiliary connection members 531 and 532 are connected to each other. It is considered that the displacement that is inclined with respect to the connection reference lines A1 and A2 is more likely to occur than the displacement that is expanded and contracted in the direction along A1 and A2. As a result, the effect of correcting the difference between the detection sensitivity for the moments Mx, My and the detection sensitivity for the forces Fx, Fy can be obtained.

FIG. 32 shows the amount of variation (increase/decrease) in the capacitance value of each capacitance element when a force in each axial direction or a moment around each axis acts on the force receiving body 100 in the third embodiment shown in FIG. FIG. The sign of each column is "+" or "-", and it can be seen that the difference in the detection sensitivity of each axis component is largely corrected by comparison with the table shown in FIG.

Of course, since the reference numerals in each column in these tables indicate relative detection sensitivities, the addition of the auxiliary connection members 531 and 532 does not improve the detection sensitivities of the forces Fx and Fy. As described above, when the auxiliary connecting members 531 and 532 are added, the detection sensitivity of any axial component decreases, but the detection sensitivity to the moments Mx and My significantly decreases, and the detection sensitivity to the forces Fx and Fy is reduced. Since there is only a slight decrease in, the detection sensitivities for each axis component are balanced. In order to increase the detection sensitivity of the force sensor as a whole, as described above, the thickness of the first deforming portion 61 and the second deforming portion 62 that form the detecting portion D may be reduced.

In the embodiment shown in FIG. 31, the connection reference lines A1 and A2 indicating the arrangement positions of the auxiliary connection members 531 and 532 are set as straight lines passing through the action points Q1 and Q2 and parallel to the Z axis. The position of the reference line is not necessarily limited to this position. For example, the auxiliary connection member 531 may be arranged so that the connection reference line A3 shown in FIG. 31 becomes the central axis, or the auxiliary connection member 532 may be arranged so that the connection reference line A4 shown in FIG. 31 becomes the central axis. You may. Here, the connection reference line A3 is a straight line parallel to the Z axis, passing through the movement point obtained by moving the action point Q1 in the positive direction of the X axis, and the connection reference line A4 moves the action point Q2 in the negative direction of the X axis. It is a straight line that passes through the moved point and is parallel to the Z axis. The auxiliary connection members arranged at the positions of the connection reference lines A3 and A4 serve to connect the lower surface of the force receiving body 100 and the upper surface of the connection member 300.

Since the connection reference lines A1 to A4 are all straight lines that are orthogonal to the X axis, if the auxiliary connection member is arranged at this position, the detection sensitivity of the moment My that has the highest detection sensitivity among the six axis components is effective. Can be suppressed. Of course, the auxiliary connection member does not necessarily need to be arranged at an accurate position with the connection reference lines A1 to A4 as the central axis, and even if it is arranged at a position slightly deviated from the connection reference lines A1 to A4, the detection sensitivity difference is The effect of correction can be obtained.

After all, in order to correct the difference in detection sensitivity, the action points Q1 and Q2 or the movement point obtained by moving the action points Q1 and Q2 along the line connecting the origin O and the action points Q1 and Q2 are passed through the Z-axis. Auxiliary connection members for connecting the lower surface of the detection ring 600 or the force receiving body 100 to the upper surface of the support substrate 300 along the connection reference lines A1 to A4 or in the vicinity thereof. 531 and 532 may be provided.

Since the role of the auxiliary connection members 531 and 532 is to balance the detection sensitivities of the respective axial components, it is necessary to maintain the detection sensitivities for the forces Fx and Fy as much as possible and reduce the detection sensitivities for the moment My. is there. For that purpose, as the auxiliary connection members 531, 532, when the force acts in the direction orthogonal to the connection reference lines A1 to A4, compared to when the force acts in the direction along the connection reference lines A1 to A4. However, it is preferable to use a member that easily causes elastic deformation. In other words, a member is used which is less likely to elastically deform when a force in the direction parallel to the Z axis is applied, but easily elastically deforms when a force in the direction perpendicular to the Z axis is applied. Is preferred.

The auxiliary connection members 531 and 532 shown in FIG. 31 are columnar members that extend in the Z-axis direction, and have the property of being difficult to expand and contract in the Z-axis direction, but easy to incline in the Z-axis direction. The material is suitable as an auxiliary connecting member. Actually, the degree of elastic deformation may be adjusted depending on the thickness of the auxiliary connecting member. Of course, the shape of the auxiliary connecting member is not limited to the cylindrical shape, and any shape may be adopted.

Specifically, elongated rod-shaped members made of a material having elasticity to some extent, such as metal or resin, may be used as the auxiliary connection members 531 and 532, which may be arranged along a predetermined connection reference line. Then, when the support substrate 300 is fixed and the force is applied to the force receiving body 100 in the direction along the connection reference line, elastic deformation hardly occurs, and the force is applied in the direction orthogonal to the connection reference line. When applied, elastic deformation is likely to occur. In other words, the auxiliary connecting members 531 and 532 made of elongated rod-shaped members are unlikely to be deformed to expand and contract in the longitudinal direction, but are likely to be deformed to incline the whole. As a result, the displacement of the detection ring 600 in the Z-axis direction is suppressed more effectively than the displacements in the X-axis direction and the Y-axis direction, and the detection sensitivity difference for each axis component can be corrected.

FIG. 33 is a partial cross-sectional view showing a modified example of the structure near the auxiliary connecting member 532 shown in FIG. In this modified example, the auxiliary connecting member 532 is devised so as to be more easily tilted, and a diaphragm structure is adopted for the connecting portions at both ends of the auxiliary connecting member.

Similar to the auxiliary connection member 532 shown in FIG. 31, the auxiliary connection member 532d shown in FIG. 33 is a columnar structure arranged such that the connection reference line A2 passing through the point of action Q2 serves as the central axis, and the detection is performed. It plays a role of connecting the ring 600 and the support substrate 300. However, the upper end of the auxiliary connection member 532d is connected to the lower surface of the diaphragm portion 600d, and the lower end is connected to the upper surface of the diaphragm portion 300d. Here, the diaphragm portion 600d is a thin-walled portion formed in the connecting portion L of the detection ring 600, and in order to form this diaphragm portion 600d, a groove portion G1 is formed on the lower surface of the detection ring 600. .. On the other hand, the diaphragm portion 300d is a thin portion formed on the support substrate 300, and the groove portion G2 is formed on the upper surface of the support substrate 300 in order to form the diaphragm portion 300d.

FIG. 33 shows the structure in the vicinity of the auxiliary connection member 532d having the connection reference line A2 as its central axis, but the same diaphragm portion is also provided at the upper and lower connection portions of the auxiliary connection member 531d having the connection reference line A1 as its central axis. 600d and 300d are formed. When the connecting structure using such a diaphragm is adopted, the auxiliary connecting members 531d and 532d are displaced by the deformation of the diaphragm portions 600d and 300d, so that the auxiliary connecting members 531d and 532d themselves do not need to be deformed. Therefore, members having thick rigidity may be used as the auxiliary connecting members 531d and 532d. In order to secure a sufficient inclination angle, it is preferable to make the auxiliary connection members 531d and 532d as long as possible.

In the example shown in FIG. 33, the upper end of the auxiliary connection member 532d is connected to the detection ring 600 via the diaphragm portion 600d, and the lower end of the auxiliary connection member 532d is connected to the support substrate 300 via the diaphragm portion 300d. However, it is also possible to adopt a configuration in which only the upper end or only the lower end is connected via the diaphragm portion.

After all, when adopting a configuration in which the auxiliary connecting member is connected via the diaphragm portion, the connecting portion of the detecting ring or the force receiving member to the auxiliary connecting member, or the connecting portion of the supporting substrate to the auxiliary connecting member, or these connecting portions. Both of them may be constituted by a diaphragm portion, and the auxiliary connecting member may be inclined with respect to the connection reference line by the deformation of the diaphragm portion caused by the action of force or moment.

The third embodiment shown in FIG. 31 is obtained by adding auxiliary connecting members 531 and 532 to the force sensor according to the first embodiment shown in FIG. 16, and according to the third embodiment, as shown in FIG. The results shown in the table of FIG. 32 are obtained instead of the table of 20. However, based on the table of FIG. 32, it is not possible to obtain accurate detection values without interference of the other axis components for all the six axis components Fx, Fy, Fz, Mx, My, Mz. Rather, it is not possible to perform an approximation in which the variation amount of the electrostatic capacitance value when the forces Fx and Fy act is 0, and thus the degree of interference of the other axis components increases.

In order to obtain accurate detection values without interference of the other axis components for all of the six axis components Fx, Fy, Fz, Mx, My, Mz, the second embodiment (8 sets of detection units) described in §5. The embodiment in which the auxiliary connection member is added to the above embodiment). Specifically, with respect to the basic structure portion according to the second embodiment shown in FIG. 27, at four positions of the action points Q11 to Q14 (or at positions of movement points obtained by moving these points outward), Connection reference lines parallel to the Z-axis may be defined, and four sets of auxiliary connection members may be provided on or near each connection reference line. These auxiliary connecting members serve to connect the lower surface of the connecting portion L of the detection ring 700 and the upper surface of the support substrate 300. Of course, the upper end and the lower end of the auxiliary connecting member may be connected via a diaphragm portion as shown in FIG. 33, if necessary.

FIG. 34 shows a force sensor in which four sets of auxiliary connecting members are added to the second embodiment described in §5, in each capacitive element when a force in each axial direction or a moment around each axis acts. It is a table showing the variation amount (degree of increase or decrease) of the electrostatic capacitance value. The sign of each column is "+" or "-", and it can be seen that the difference in the detection sensitivity of each axis component is largely corrected by comparison with the table shown in FIG. In the second embodiment, as described in §5, the interference based on the other axis components is eliminated from all the six axis components Fx, Fy, Fz, Mx, My, and Mz by the calculation based on the calculation formula shown in FIG. The detected value obtained can be obtained. Therefore, by adding four sets of auxiliary connecting members to the second embodiment, it is possible to accurately detect the six axis components and correct the difference in the detection sensitivity of each axis component. As mentioned above, it is difficult to completely eliminate the interference of other axis components, but in practice, it can be suppressed to a level that does not cause any problems, and if necessary, by using a microcomputer or the like, It is also possible to make a correction to remove the other axis component.

Note that it is not always necessary to use all four sets of auxiliary connection members, and if at least one set is used, the effect of correcting the difference in detection sensitivity can be obtained. For example, in the second embodiment shown in FIG. 27, if the auxiliary connecting members are provided at the positions of the two sets of action points Q11 and Q13, the displacement when the moment My acts can be significantly suppressed. Therefore, it is possible to correct at least the detection sensitivity to the moment My.

<<<< §7. Embodiment using square detection ring >>>
The embodiments described so far are all force sensors having circular portions. For example, in the case of the force sensor according to the first embodiment shown in FIG. 16, the detection ring 600 is an annular structure whose basic annular path B is a circle arranged in the XY plane with the Z axis as the central axis. The support body (support substrate) 300 is a circular plate-like structure arranged in the Z axis negative region with the Z axis as the central axis, and the force receiving body 100 is arranged in the XY plane with the Z axis as the central axis. It is a circular annular structure.

In the fourth embodiment described here, each part is configured by a square member. For example, as the detection ring, a square detection ring 700S as shown in FIG. 35 can be used. This detection ring 700S is obtained by modifying the shape of the detection ring 700 shown in FIG. 24 into a square, and the basic structure is similar. Therefore, as the reference numeral of each part of the detection ring 700S shown in FIG. 35, the reference numeral of the corresponding part of the detection ring 700 shown in FIG. 24 with S (an acronym for Square) added thereto is used. Note that, while FIG. 24 is a bottom view and FIG. 35 is a top view, the direction of the Y axis is reversed.

In the case of the detection ring 700 shown in FIG. 24, eight sets of detection units D11 to D18 are arranged clockwise on the circular detection ring 700. On the other hand, since FIG. 35 is a top view, eight sets of detection units D11S to D18S are arranged counterclockwise on the square detection ring 700S. As illustrated, the first detection unit D11S includes a first deformation unit 71S and a second deformation unit 72S, and a displacement unit 73S whose both ends are supported by the first deformation unit 71S and the second deformation unit 72S. The same applies to the structures of the second to eighth detectors D12S to D18S.

The basic structure and modification of the detectors D11S to D18S are the same as the basic structure and modification of the detector D shown in FIG. Of course, the detection unit formed on the circular detection ring 700 and the detection unit formed on the square detection ring 700S are slightly different in shape, but the essential structure and modification are the same. .. Therefore, when the capacitive element C is formed by the displacement electrode E2 formed on the displacement portion 73S of each of the detection portions D11S to D18S and the fixed electrode E1 formed on the opposing position of the support substrate, along the basic annular path BS. The increase and decrease in the capacitance value of the capacitive element C are reversed between when the compressive stress is applied and when the tensile stress is applied.

Although illustration is omitted here, the force receiving body 100S formed of a square annular structure surrounding the outer side of the square force receiving ring 700S and the outer contour line of the force receiving body 100S are the same as the shape of the square detection ring 700S. A support body (support substrate) 300S made of a plate-shaped structure having a square is prepared. That is, in the fourth embodiment described here, the detection ring 700S is an annular structure whose base annular path BS is a square arranged in the XY plane with the Z axis as the central axis, and the support (support substrate) 300S. Is a square plate-like structure arranged in the Z-axis negative region with the Z-axis as the central axis, and the force receiving body 100S is a square annular structure arranged in the XY plane with the Z-axis as the central axis. become.

Of course, a connecting member is connected between the force receiver 100S and the detection ring 700S, and a fixing member is connected between the detection ring 700S and the support substrate 300S. However, these connection positions are slightly different from those of the second embodiment described in §5. In the case of the fourth embodiment, as shown in FIG. 35, two sets of fixed points P15 and P16 are defined on the X axis of the detection ring 700S, and the positions of these fixed points P15 and P16 are determined by the fixing members 515 and 525. It is fixed to the support substrate 300S. On the other hand, two sets of action points Q15 and Q16 are defined on the Y axis of the detection ring 700S, and the positions of these action points Q15 and Q16 are connected to the force receiver 100S by a connecting member (not shown).

FIG. 36 is a top view showing the region distribution of the detection ring 700S shown in FIG. 35 (the mesh hatching is for showing the regions of the detection portions D11S to D18S, and is not a cross section). As illustrated, the detection ring 700S has a structure in which eight sets of detection units D11S to D18S are connected by eight sets of connection units L11S to L18S. While the detection parts D11S to D18S are configured by three plate-shaped pieces, the connection parts L11S to L18S are configured from thick members, and when an external force acts on the detection ring 700S, the external force is applied. The elastic deformation of the detection ring 700S based on is concentrated on the detection units D11S to D18S.

When a square basic annular road BS as shown by a thick dashed-dotted line in FIG. 36 is defined, the first connecting portion L11S, the first detecting portion D11S, and the second basic annular road BS are formed counterclockwise along the basic annular road BS. Connecting portion L12S, second detecting portion D12S, third connecting portion L13S, third detecting portion D13S, fourth connecting portion L14S, fourth detecting portion D14S, fifth connecting portion L15S, fifth The detection section D15S, the sixth connection section L16S, the sixth detection section D16S, the seventh connection section L17S, the seventh detection section D17S, the eighth connection section L18S, and the eighth detection section D18S are arranged in this order. By arranging them, the detection ring 700S is configured.

<I>, <II>, <III>, and <IV> in the figure show the first to fourth quadrants in the XY two-dimensional coordinate system. The eight detection units D11S to D18S are arranged in two sets in each quadrant.

FIG. 37 is a plan view showing the basic ring road BS defined on the XY plane and the points defined on the basic ring road BS for the detection ring 700S shown in FIG. The basic ring road BS shown by a thick dashed line in the figure is a square centered on the origin O arranged on the XY plane, and the detection ring 700S is a rectangular ring structure extending along the base ring road BS. Become. In the drawing, the positions of the inner contour line and the outer contour line of the detection ring 700S are shown by solid lines. In the illustrated embodiment, the basic annular path BS is a square on the XY plane that passes through the intermediate position between the inner contour line and the outer contour line of the detection ring 700S, and the annular thick portion of the detection ring 700S (the connecting portion L11S). ~L18S).

As can be seen from FIG. 37, the fixed point P and the action point Q are not provided between the detection points R11 and R12 in the fourth embodiment. Similarly, neither the fixed point P nor the action point Q is provided between the detection points R13 and R14, between the detection points R15 and R16, and between the detection points R17 and R18. In other words, in the fourth embodiment, when the even-numbered n connecting portions are sequentially numbered along the basic annular path, the action point Q and the fixed point P are both odd-numbered. The policy is such that the points of action Q and the fixed points P are arranged at the connecting portion and are arranged alternately along the basic annular road BS.

Specifically, as can be seen by comparing FIGS. 36 and 37, the first fixed point P15 is arranged at the first connecting portion L11S, and the first action point Q15 is arranged at the third connecting portion L13S. The second fixed point P16 is arranged at the fifth connecting portion L15S, and the second action point Q16 is arranged at the seventh connecting portion L17S. That is, the fixed points P15 and P16 and the action points Q1 and Q2 are arranged alternately in the odd-numbered connecting portions, and the fixed point P also acts in the even-numbered connecting portions. Q is not placed either.

Here, the position of the first action point Q15 of the detection ring 700S is connected to the force receiving body 100S by the first connection member, and the position of the second action point Q16 of the detection ring 700S is the position of the second connection member. Is connected to the force receiving body 100S (illustration of each connecting member is omitted). Similarly, the position of the first fixed point P15 of the detection ring 700S is fixed to the support substrate 300S by the first fixed member 515, and the position of the second fixed point P16 of the detection ring 700S is set to the second fixed member. It is fixed to the support substrate 300S by 525 (see FIG. 35).

More specifically, in the illustrated example, the first fixed point P15 is arranged on the positive X axis, the second fixed point P16 is arranged on the negative X axis, and the first action point Q15. Are arranged on the positive Y-axis, and the second action point Q16 is arranged on the negative Y-axis. The detection ring 700S is a square annular structure arranged on the XY plane with the origin O as the center, and extends in a direction parallel to the Y-axis and intersects the positive X-axis with the first side S1 and the X-axis. A second side S2 extending in the direction parallel to the positive Y-axis, a third side S3 extending in the direction parallel to the Y-axis and a negative X-axis extending in the direction parallel to the X-axis. And a fourth side S4 that intersects the negative Y-axis.

Then, the first detection point R11 is arranged at a position having the positive Y coordinate of the first side S1, and the second detection point R12 is arranged at a position having the positive X coordinate of the second side S2. The third detection point R13 is arranged at the position having the negative X coordinate of the second side S2, and the fourth detection point R14 is arranged at the position having the positive Y coordinate of the third side S3. The fifth detection point R15 is arranged at the position having the negative Y coordinate of the third side S3, and the sixth detection point R16 is arranged at the position having the negative X coordinate of the fourth side S4. The seventh detection point R17 is arranged at the position having the positive X coordinate of the fourth side S4, and the eighth detection point R18 is arranged at the position having the negative Y coordinate of the first side S1. Has been done.

In the force sensor according to the fourth embodiment described here, the capacitive elements C11 to C18 are formed for each of the eight sets of detection units D11S to D18S arranged at the positions of such eight sets of detection points R11 to R18. To be done. With respect to the force sensor, the fluctuation amount (degree of increase/decrease) of the capacitance values C11 to C18 of the capacitance elements C11 to C18 when a force in each axis direction or a moment around each axis is applied is shown in the table of FIG. As shown in. Here, the column marked with “0” indicates that no significant variation occurs, and the column marked with “+” or “−” indicates that the capacitance value increases or decreases. .. Further, the columns marked with "++" or "-" indicate that the degree of increase or decrease of the capacitance value is larger.

Assuming the results shown in the table of FIG. 38, the 6-axis components Fx, Fy, Fz, Mx, My, Mz of the external force acting on the force receiving body 100S can be calculated by the arithmetic expression shown in FIG. it can.

First, the force Fx in the X-axis direction is obtained by the calculation of Fx=+C12-C13-C16+C17 by referring to each column of the row of Fx in the table of FIG. Similarly, the force Fy in the Y-axis direction can be obtained by the calculation Fy=−C11−C14+C15+C18 by referring to each column of the Fy row in the table of FIG. Then, the force Fz in the Z-axis direction is obtained by the calculation of Fz=−(C11+C12+C13+C14+C15+C16+C17+C18) by referring to each column of the Fz row of the table in FIG.

On the other hand, the moment Mx about the X axis can be obtained by the calculation of Mx=−C11−C12−C13−C14+C15+C16+C17+C18 by referring to each column of the row of Mx in the table of FIG. Similarly, the moment My about the Y axis can be obtained by the calculation of My=+C11+C12-C13-C14-C15-C16+C17+C18 by referring to each column of the row of My in the table of FIG. Then, the moment Mz about the Z axis is obtained by the calculation of Mz=-C11-C12+C13+C14-C15-C16+C17+C18 by referring to each column of the row of Mz in the table of FIG.

The basic structure portion configured by using the detection ring 700S shown in FIG. 35 has symmetry with respect to both the XZ plane and the YZ plane. Therefore, by using the respective arithmetic expressions shown in FIG. 39, it is possible to obtain a detection value in which the interference of the other axis components is eliminated. Although illustration is omitted here, if a detection circuit for performing the calculation based on the calculation formula shown in FIG. 39 is prepared, the voltage values corresponding to the 6-axis components Fx, Fy, Fz, Mx, My, and Mz are electrically converted. It can be output as a signal. As mentioned above, it is difficult to completely eliminate the interference of other axis components, but in practice, it can be suppressed to a level that does not cause any problems, and if necessary, by using a microcomputer or the like, It is also possible to make a correction to remove the other axis component.

Note that the arithmetic expression shown in FIG. 39 shows an example of an arithmetic expression for calculating each axis component, and it is also possible to calculate each axis component by using an arithmetic expression different from this. For example, the force Fz can be obtained by an arithmetic expression Fz=-(C11+C13+C15+C17) or Fz=-(C12+C14+C16+C18), and the moment Mx can be obtained by an arithmetic expression Mx=-C12-C13+C16+C17. And the moment My can be obtained by an arithmetic expression My=+C11-C14-C15+C18, and the moment Mz can be obtained by an arithmetic expression Mz=-C11+C13-C15+C17 or Mz=-C12+C14-C16+C18. Is possible.

FIG. 40 is a diagram showing a variation of such an arithmetic expression. Theoretically, a more accurate detection value can be obtained by performing an operation using all of the eight sets of capacitance values C11 to C18, but in reality, each of the variations shown in FIG. Even if the calculation based on the calculation formula is performed, it is possible to obtain the detection result with sufficient accuracy in practical use. Therefore, in order to reduce the calculation load of the detection circuit as much as possible, the variation shown in FIG. 40 may be adopted.

<<<<§8. Other variants >>>
Although some embodiments of the force sensor according to the present invention have been described so far, some modifications will be described here.

<8-1. Modified example in which the positions of the action points and fixed points are changed>
FIG. 41 is a top view of the basic structure portion of the force sensor according to the fifth embodiment of the present application. Like the second embodiment shown in FIG. 27, the fifth embodiment is a force sensor in which each unit has a circular shape and uses eight sets of detection units D11 to D18. The basic structure part of the force sensor according to the fifth embodiment shown in FIG. 41 is almost the same as the basic structure part of the force sensor according to the second embodiment shown in FIG. The same members are used for the force receiving body 100 and the support substrate 300. Therefore, the structure and arrangement of the eight sets of detection units D11 to D18 are not changed, and the structure and arrangement of the eight sets of capacitive elements are not changed.

That is, in the basic structure portion shown in FIG. 41, the detection ring 700 is a circular annular structure arranged on the XY plane with the origin O as the center, and on the XY plane, with the origin O as the starting point, the detection ring 700 moves in the positive direction of the X axis. On the other hand, when the azimuth vector Vec(θ) forming the angle θ counterclockwise is defined, the ith (where 1≦i≦8) detection point is the azimuth vector Vec(π/8+(i−1). )·Π/4) and the basic loop road B are located at the intersections. This is a structure common to the basic structure part shown in FIG. The difference between the two is the positions of the action point Q and the fixed point P, and the configuration of the detection circuit (arithmetic expression used).

In the case of the basic structure shown in FIG. 27, four sets of action points Q11 to Q14 (white circles) are arranged on the X axis or the Y axis, and four sets of fixed points P11 to P14 (black circles) are on the V axis or the W axis. It is located in. Therefore, the detection ring 700 is connected to the force receiving body 100 by the four sets of connecting members 460, 470, 480, 490, and is connected to the support substrate 300 by the four sets of fixing members 560, 570, 580, 590. ..

On the other hand, in the case of the basic structure shown in FIG. 41, two sets of action points Q15 and Q16 (white circles) are arranged on the Y axis, and two sets of fixed points P15 and P16 (black circles) are located on the X axis. It is arranged. Therefore, the detection ring 700 is connected to the force receiver 100 by the two sets of connecting members 470 and 490, and is connected to the support substrate 300 by the two sets of fixing members 516 and 526.

After all, the force sensor according to the fifth embodiment shown in FIG. 41 has an outer shape similar to that of the force sensor according to the second embodiment shown in FIG. 27, but has a working point Q and a fixed point P. The arrangement is the same as that of the force sensor according to the fourth embodiment using the square member shown in FIG. In the fourth embodiment, when numbers are sequentially assigned to the even-numbered n connecting portions along the basic loop road BS, the action point Q and the fixed point P are arranged at the odd-numbered connecting portions. In addition, the action point Q and the fixed point P are alternately arranged along the basic ring road BS. Also in the fifth embodiment shown in FIG. 41, since the action point Q and the fixed point P are arranged based on the above-described policy, both the action point Q and the fixed point P are located on the V axis and the W axis. Not placed.

Therefore, the variation mode of the electrostatic capacitance values of the eight sets of capacitive elements C11 to C18 in the force sensor according to the fifth embodiment is different from the table shown in FIG. 28 (the table for the second embodiment). The arithmetic expression used to detect each axis component is also different from the arithmetic expression shown in FIG. 29 (the arithmetic expression in the second embodiment). Here, the description of the table showing the variation mode of the capacitance value and the arithmetic expression used to detect each axis component in the fifth embodiment will be omitted, but in practice, the table shown in FIG. A calculation formula close to the calculation formula 39 is obtained.

As described above, when the present invention is carried out, even if the detection rings having the same physical structure are used, the deformation modes of the detection ring are different depending on the positions of the action point Q and the fixed point P. It should be kept in mind that the calculation formula for obtaining the axis component also differs.

<8-2. Modified example in which the force receiving body is arranged inside>
In the embodiments described so far, an annular structure capable of accommodating the detection ring is used as the force receiving body, and the force receiving body is arranged outside the detection ring. It does not have to be located outside the ring. For example, if the detection ring is an annular structure capable of accommodating the force receiving body inside, the force receiving body can be arranged inside the detection ring.

FIG. 42 is a top view (upper view) of a basic structure portion of a force sensor according to a sixth embodiment of the present invention and a side cross-sectional view (lower view) taken along the XZ plane. The detection ring 700 in the basic structure part shown in FIG. 42 is exactly the same as the detection ring 700 in the basic structure part according to the second embodiment shown in FIG. 27, and the structure of the eight detection parts D11 to D18 and There is no difference in the arrangement, the structure or arrangement of the eight sets of capacitive elements C11 to C18, the arrangement of the four sets of action points Q11 to Q14, and the arrangement of the four sets of fixed points P11 to P14. However, the force receiving body 100 shown in FIG. 27 is an annular structure arranged outside the detection ring 700, whereas the force receiving body 150 shown in FIG. 42 is arranged inside the detection ring 700. It has a columnar structure.

Therefore, the arrangement of the four sets of fixing members 560, 570, 580, 590 for fixing the detection ring 700 to the support substrate 380 is the same as that in the second embodiment, but the detection ring 700 is used as the force receiving member 150. Four sets of connection members 465, 475, 485, 495 for connection are provided inside the detection ring 700. That is, since the four sets of connecting members 465, 475, 485, 495 connect the positions of the action points Q11 to Q14 of the detection ring 700 to the force receiving body 150, the inner peripheral surface of the detection ring 700 and the force receiving body 150 are connected. It is provided as a member for connecting to the outer peripheral surface.

As can be seen from the side sectional view in the lower part of FIG. 42, since the force receiving body 150 is housed inside the detection ring 700, the support substrate 380 has a disk having an outer diameter equal to the outer diameter of the detection ring 700. It is configured by a member having a shape. Therefore, the radial size of the basic structure portion can be set small. In the illustrated example, since the thickness of the force receiving body 150 is set to be larger than the thickness of the detection ring 700, the upper end of the force receiving body 150 has a structure protruding upward. In that case, the thickness of the force receiving body 150 may be made equal to the thickness of the detection ring 700.

As described above, when the structure in which the force receiver 150 is housed inside the detection ring 700 is adopted, the inner cavity of the detection ring 700 can be effectively used, and the device can be downsized. However, the detection ring 700 that is deformed when subjected to the action of an external force is exposed to the outside, and therefore when the portion of the detection ring 700 comes into contact with any object, the detection ring 700 is originally deformed (described above). The deformation necessary for the detection principle) is hindered, and a correct detection result cannot be obtained. Therefore, when adopting the sixth embodiment, it is preferable to consider such as providing a protective cover on the outside so that the original deformation of the detection ring 700 is not hindered.

The detection operation of each axial component in the force sensor according to the sixth embodiment is the same as the operation of the force sensor according to the second embodiment described in §5, and thus the description thereof is omitted here.

<8-3. Modified example in which the force receiving body is arranged above>
In §8-2, the modification in which the force receiving body is arranged inside the detection ring is described, but the arrangement of the force receiving body is not limited to the outside or the inside of the detection ring. Theoretically, what kind of position the force receiving body should have is that it can transmit the force or moment to be detected to the action point Q of the detection ring without disturbing the original deformation of the detection ring. You can place it in any position. Here, a modification in which the force receiving body is arranged above the detection ring will be described.

FIG. 43 is a top view (upper view) of a basic structure portion of a force sensor according to a seventh embodiment of the present invention and a side cross-sectional view (lower view) taken along the XZ plane. The detection ring 700 and the support substrate 380 in the basic structure portion shown in FIG. 43 are exactly the same as the detection ring 700 and the support substrate 380 in the basic structure portion according to the sixth embodiment shown in FIG. The arrangement of the fixing members 560, 570, 580, 590 is also the same.

However, the force receiving body 150 shown in FIG. 42 is a columnar structure arranged inside the detection ring 700, whereas the force receiving body 180 shown in FIG. 43 is arranged above the detection ring 700. It has a disc-shaped structure. In the case of this example, the force receiving body 180 is configured by a disk-shaped member having an outer diameter equal to the outer diameter of the detection ring 700, that is, a member having the same shape as the support substrate 380.

Therefore, the arrangement of the four sets of fixing members 560, 570, 580, 590 for fixing the detection ring 700 to the support substrate 380 is the same as that of the sixth embodiment, but the detection ring 700 is used as the force receiving member 180. The four sets of connection members 491, 492, 493, 494 for connection are provided above the detection ring 700. As shown by the broken lines in the upper diagram of FIG. 43, the four sets of connecting members 491, 492, 493, 494 are cylindrical members and receive the positions of the action points Q11 to Q14 of the detection ring 700. In order to connect to the force body 180, it is provided as a member that connects the upper surface of the detection ring 700 and the lower surface of the force receiver 180.

After all, in the force sensor according to the seventh embodiment, when the XY plane is a horizontal plane and the Z axis is an axis directed vertically upward, the detection ring 700 is arranged on the XY plane and the support (support substrate 380) is arranged. ) Is arranged below the detection ring 700 at a predetermined interval, and the force receiving body 180 is arranged above the detection ring at a predetermined interval.

As described above, even when the force receiver 180 is arranged above the detection ring 700, there is no change in the function of transmitting the force or moment to be detected to the action points Q11 to Q14 of the detection ring 700. The operation of detecting each axial component in the force sensor according to the seventh embodiment is also the same as the operation of the force sensor according to the second embodiment described in §5, so description thereof will be omitted here.

<8-4. Other modifications regarding the shape and arrangement of the force receiving body and the support>
In the first to fifth embodiments described so far, the force receiving body 100 made of the annular structure is used, but this is a convenience for disposing the force receiving body 100 outside the detection ring. On the other hand, the force receiving body 150 (FIG. 42) used in the sixth embodiment described in §8-2 has a cylindrical shape, and the force receiving body 180 (FIG. 42) used in the seventh embodiment described in §8-3 is used. 43) has a disc shape. As described above, the shape of the force receiving body may be an annular structure or a plate-like structure as long as it is designed to have an appropriate shape in each embodiment. Of course, it may be a circular structure or a rectangular structure.

Similarly, in the first to seventh embodiments described so far, the support substrates 300 and 380 made of a plate-shaped structure are used as the support, but the support in the present invention serves to support the detection ring. Any member can be used as long as it fulfills the requirements, and its shape may be arbitrary. Therefore, the plate-shaped structure is not necessarily required, and an annular structure can be used as the support.

Further, in the first to seventh embodiments described so far, the support (supporting substrates 300, 380) is arranged below the detection ring, but the support is not necessarily below the detection ring (the detection ring is XY. It is not necessary to arrange it in the Z-axis negative region when it is arranged on the plane, and it can be arranged at any position. However, if the supporting body is composed of the supporting substrate arranged below the detection ring, the fixed electrode can be formed on the upper surface of the supporting substrate. Therefore, in order to simplify the manufacturing process, the plate arranged below the detection ring. It is preferable that the support is constituted by a structural body.

<8-5. Variation of detector>
Here, variations regarding the structure of the detection unit D will be described. In each of the embodiments described so far, the detection unit D having the structure illustrated in FIG. 17 is used. The detection unit D has a first deforming portion 61 and a second deforming portion 62 that are elastically deformed, and a displacement portion 63 that is displaced by the elastic deformation of the deforming portions 61 and 62.

More specifically, as shown in FIG. 17(a), the detection unit D arranged at the position of the detection point R includes a first plate-shaped piece 61 and a second plate-shaped piece 62 that elastically deform, Both ends are constituted by a third plate-shaped piece 63 supported by these plate-shaped pieces 61, 62, and the third plate-shaped piece 63 functions as a displacement portion. Here, when the normal line N orthogonal to the XY plane is set at the position of the detection point R, the first plate-shaped piece 61 and the second plate-shaped piece 62 are inclined with respect to the normal line N. Moreover, the inclination direction of the first plate-shaped piece 61 and the inclination direction of the second plate-shaped piece 62 are opposite to each other. Further, in the state where no force or moment is applied, the facing surface of the third plate-shaped piece 63 (displacement portion) and the facing surface of the support substrate 300 are kept parallel to each other.

Here, paying attention to the planar shape of the detecting portion in the embodiments shown in FIGS. 13, 16, 24, 27, 31, 31, 41, and 42 described above, the first plate-shaped piece 61, The projected images of 71 and the second plate-shaped pieces 62, 72 and the third plate-shaped pieces 63, 73 on the XY plane are all fan-shaped, and the left and right contour lines of the projected images are It is along the radius toward the origin O. For example, the planar shapes of the plate-shaped pieces 61, 62, 63 forming the detection unit D4 shown in FIG. 13(c) are all fan-shaped, which is close to a trapezoid. This is because the detection ring 600 has an annular shape, and the detection units D1 to D4 are designed in accordance with the annular shape.

On the other hand, in the embodiment shown in FIG. 35, for example, the planar shapes of the plate-shaped pieces 71S, 72S, 73S forming the detection unit D11S are all rectangular. This is because the detection ring 700S has a quadrangular shape, and the detection units D11S to D18S are designed in accordance with the quadrangular shape.

As described above, in the above-described embodiments, the planar shape of each plate-shaped piece that constitutes the detection unit is designed to be a fan shape or a rectangle according to the shape of the detection ring. It is not always necessary to properly use the plane shape of (1) as in the above example. For example, as shown in FIG. 13(c), even if the annular detection ring 600 is adopted, the planar shapes of the plate-like pieces 61, 62, 63 are all designed to be rectangular. It doesn't matter. In the embodiment shown in FIG. 13(c), if the planar shape of each plate-like piece 61, 62, 63 is made into a rectangle like the plate-like pieces 71S, 72S, 73S shown in the embodiment of FIG. When the three-dimensional structure of D is formed by cutting or wire cutting, a simple process of driving the processing tool in the same direction can be adopted, which is preferable for mass production of the sensor.

The detector D having the cross-sectional structure illustrated in FIG. 17(a) is one of the detectors having the most preferable structure in carrying out the present invention, but the detector that can be used in the present invention The structure of D is not limited to the structure illustrated in FIG. 17(a). FIG. 44 is a partial cross-sectional view showing a variation of the structure of the detection unit D.

The detection unit DB shown in FIG. 44(a) is a detection unit provided in a part of the detection ring 600B, and includes a first plate-shaped piece 61B, a second plate-shaped piece 62B, a displacement section 63B, and a first plate-shaped piece 62B. It has a bridge portion 64B and a second bridge portion 65B. As shown in the figure, the displacement portion 63B, the first bridge portion 64B, and the second bridge portion 65B are all plate-shaped and arranged so as to be parallel to the XY plane (the plane including the basic annular road B). The first plate-shaped piece 61B and the second plate-shaped piece 62B, which are constituent elements, are arranged so as to be orthogonal to the XY plane (parallel to the normal line N). It is a component of the shape.

In the case of the detection unit D shown in FIG. 17(a), the first plate-shaped piece 61 and the second plate-shaped piece 62 are inclined so that they are in opposite directions. In the case of the part DB, the first plate-shaped piece 61B and the second plate-shaped piece 62B are parallel to each other. Therefore, in the detection unit DB, the first plate-shaped piece 61B and the second plate-shaped piece 62B are inclined with respect to the normal line N regardless of whether the compression force f1 or the extension force f2 is applied. Therefore, in either case, the displacement portion 63B moves upward in the figure. Therefore, it is impossible to detect the direction of the acting force or moment due to the increase or decrease of the capacitance value of the capacitive element C, but if the application is such that the direction of the acting force or moment is fixed, the detecting unit DB acts. It is possible to detect the magnitude of the applied force or moment.

The detection unit DC shown in FIG. 44(b) is a detection unit provided in a part of the detection ring 600C, and includes a first plate-shaped piece 61C, a second plate-shaped piece 62C, a displacement portion 63C, and a first plate-shaped piece 61C. It has a bridge portion 64C and a second bridge portion 65C. As shown in the figure, the displacement portion 63C, the first bridge portion 64C, and the second bridge portion 65C are all plate-shaped and arranged so as to be parallel to the XY plane (the plane including the basic annular road B). The first plate-shaped piece 61C and the second plate-shaped piece 62C, which are constituent elements, are plate-shaped constituent elements that are inclined with respect to the normal line N so as to be opposite to each other. However, it differs from the detection unit D shown in FIG. 17(a) in the manner of inclination, and the distance between the plate-shaped pieces 61C and 62C increases as it goes downward in the figure.

In the detection unit DC, when the compression force f1 acts, the displacement portion 63C moves upward in the figure, and when the extension force f2 acts, the displacement portion 63C moves downward in the figure. Although the displacement direction is opposite to that of the detection unit D shown in FIG. 17A, the direction and magnitude of the applied force or moment can be detected by increasing or decreasing the capacitance value of the capacitive element C. ..

The detection unit DD shown in FIG. 44(c) is a detection unit provided in a part of the detection ring 600D, and has a very simple structure including one plate-shaped deforming unit 80. The plate-shaped deforming portion 80 is a component that elastically deforms due to the action of a force or moment to be detected, and its plate surface is arranged so as to be inclined with respect to the XY plane (the plane including the basic annular path B). Has been done. In the detection unit DD, when the compression force f1 or the extension force f2 is applied, the plate-shaped deforming unit 80 is bent.

When the capacitive element is used as the detection element as in each of the embodiments described above, a simple structure such as the detection unit DD is not so preferable, but as described later, a strain gauge is used as the detection element. In this case, a simple structure such as the detector DD is also sufficiently useful.

Of course, as the detection unit D, various structures other than this can be adopted. In short, the detecting unit used in the present invention may have any structure as long as the structure causes displacement or bending when the compressive force f1 or the expanding force f2 is applied in the direction along the basic annular path B. It doesn't matter. On the other hand, although the connecting portion may have a certain degree of flexibility, it is preferable that the connecting portion is not deformed as much as possible in order to effectively deform the detecting portion by the external force applied. Therefore, in practice, at least a part of the detection unit is an elastic deformable body that causes elastic deformation that can be significantly detected by the detection element, and the connection section is a rigid body in which significant deformation is not detected in the detection sensitivity of the detection element. Is preferred.

Further, in the embodiments described so far, the detection unit D having a structure in which the displacement portion 63 is displaced in the Z axis direction is used, but the displacement direction of the displacement portion 63 does not necessarily have to be the Z axis direction. Absent.

FIG. 45 is a top view of the basic structure part of the force sensor according to the modified example using the detection ring 800 in which the direction of the detection part is changed instead of the detection ring 600 in the first embodiment shown in FIG. 2)) and a side cross-sectional view of the same taken along the XZ plane (lower figure). The four sets of detection parts D1 to D4 provided in the detection ring 600 shown in FIG. 16 are replaced with four sets of detection parts D1′ to D4′ in the detection ring 800 shown in FIG. Here, the basic structure of the four sets of detectors D1' to D4' is similar to the structure of the detector D shown in FIG. 17(a), but the orientation on the detector ring is different.

As can be seen from the detection section D1′ in FIG. 45, the detection section D1′ includes a first plate-shaped piece 91 and a second plate-shaped piece 92 that are elastically deformed, and plate-shaped pieces 91, The third plate-shaped piece 93 is supported by 92, and the third plate-shaped piece 93 functions as a displacement portion. Here, the plate-shaped pieces 91, 92, 93 correspond to the plate-shaped pieces 61, 62, 63 shown in FIG. 17(a), respectively, but the orientations arranged with respect to the detection ring are different. ing.

That is, in the four sets of detection units D1 to D4 provided in the detection ring 600 shown in FIG. 16, the displacement portion 63 is located below the detection ring 600, and the lower surface of the displacement portion 63 is the upper surface of the support substrate 300. Is facing. On the other hand, in the four sets of detection parts D1′ to D4′ provided in the detection ring 800 shown in FIG. 45, the displacement part 93 is located outside the detection ring 800, and the outer surface of the displacement part 93 is located. Faces the inner peripheral surface of the force receiving body 100.

In other words, the four sets of detection units D1′ to D4′ shown in FIG. 45 have a structure in which the four sets of detection units D1 to D4 shown in FIG. 16 are rotated by 90° with the basic annular path B as the rotation axis. have. Therefore, when the compressive force f1 acts along the basic annular path B, the displacement portion 93 is displaced outward (see FIG. 17(b)), and when the extension force f2 acts along the basic annular path B, the displacement portion 93 is displaced. Is displaced inward (see FIG. 17(c)).

As described above, in the four sets of detection units D1 to D4 provided in the detection ring 600 shown in FIG. 16, the displacement portion 63 is displaced in the Z-axis direction, whereas in the detection ring 800 shown in FIG. In the four sets of detection units D1' to D4', the displacement unit 93 is displaced about the origin O in the radial direction of the circle drawn on the XY plane. Therefore, as shown in FIG. 45, if the displacement electrode E2 is formed on the outer surface of the displacement portion 93 and the fixed electrode E1 is formed on the inner peripheral surface of the force receiving body 100 facing the displacement electrode E2, the pair of electrodes E1 is formed. , E2 form a capacitive element C. Then, the capacitance value of the capacitive element C can be used as a parameter indicating the displacement of the displacement portion 93 in the radial direction.

Of course, the behavior of the four sets of capacitive elements C1' to C4' formed for the four sets of detection units D1' to D4' shown in FIG. 45 is formed for the four sets of detection units D1 to D4 shown in FIG. Since the behavior of the four capacitive elements C1 to C4 is different, the variation form of the electrostatic capacitance values of the four capacitive elements C1' to C4' is different from that shown in the table of FIG. However, if a table such as the table of FIG. 20 is created as a table showing the variation form of the electrostatic capacitance values of the four sets of capacitive elements C1′ to C4′, each axial component of the force or moment to be detected can be obtained. An arithmetic expression to be calculated can be derived.

Here, with respect to the force sensor shown in FIG. 45, description of a specific arithmetic expression for calculating each axis component is omitted, but the modification shown in FIG. 45 shows the following two important points. ing. The first point is that when a capacitive element is used as the detection element, the change in the electrode spacing of the capacitive element does not necessarily have to be in the Z-axis direction. Although the illustrated example is an example in which the change in the electrode spacing of the capacitive element occurs in the radial direction, it goes without saying that a capacitive element in which the change in the electrode spacing occurs in any other direction may be used.

The second point is that when the capacitive element is used as the detection element, the displacement electrode E2 needs to be provided in the detection portion (that is, the detection ring), but the fixed electrode E1 facing the displacement electrode E2 is not always supported. It is not necessary to provide it on the body (supporting substrate 300), and it may be provided on the force receiving body 100. In each of the embodiments described up to §8-4, the fixed electrode E1 is provided on the upper surface of the support substrate 300, but in the case of the modification shown in FIG. 45, the fixed electrode E1 is not the support substrate 300. It is provided on the inner peripheral surface of the annular force receiving body 100. Here, the force receiving body 100 will be displaced by the action of an external force, and as a result, the fixed electrode E1 may be displaced, but the displacement is completely linked to the displacement of the displacement electrode E2. Therefore, it is possible to detect the external force acting on the force receiving body 100 based on the variation form of the capacitance value of each of the capacitive elements C1′ to C4′.

<8-6. Modification using strain gauge>
In the embodiments described so far, the capacitive element is used as the detection element that detects the elastic deformation that occurs in the detection unit, but in implementing the present invention, the detection element is not necessarily limited to the capacitive element. Absent. Here, as the detection element, a strain gauge fixed at a position where elastic deformation of the detection portion is generated is used, and as a detection circuit, an electric signal indicating an applied force or moment is based on a change in the electric resistance of the strain gauge. A modified example using a circuit for outputting will be described.

FIG. 46 is a partial cross-sectional view showing a mode of elastic deformation of the plate-shaped deforming portion 80 constituting the detecting portion DD shown in FIG. 44(c). FIG. 46(a) shows a state in which an external force is not acting on this detection unit DD. As illustrated, the detection unit DD is configured by a plate-shaped deforming unit 80 that elastically deforms due to the action of a force or moment that is a detection target. Here, the plate-shaped deforming portion 80 is arranged so that its plate surface is inclined with respect to the basic annular road B. In reality, such detectors DD are arranged at a plurality of locations on the detector ring 600D. In other words, the detection ring 600D is an annular structure in which the plurality of plate-shaped deforming portions 80 and the plurality of connecting portions L are alternately arranged.

Now, consider the case where a compressive force f1 as shown in FIG. 46(b) acts on the position of the detection point R of the detection ring 600D. In this case, the plate-shaped deforming portion 80 is bent, but stresses shown by "-" or "+" in the figure are generated in each portion of the surface thereof. Here, "+" indicates a compressive stress (that is, a stress in the direction of contracting along the basic annular path B), and "-" indicates a tensile stress (that is, a direction of expanding in the left and right directions along the basic annular path B in the figure). Stress). As illustrated, the stress generated on the surface of the plate-shaped deforming portion 80 is concentrated near the connection end of the plate-shaped deforming portion 80 to the connecting portion L. On the other hand, when the extension force f2 acts on the position of the detection point R, a stress distribution having the opposite sign to that in FIG. 46(b) is obtained.

On the other hand, FIG. 46(c) shows a stress distribution generated when a vertical force acts on the pair of adjacent connecting portions L. Specifically, in the illustrated example, when a downward force f3 in the figure acts on the left connecting portion L and an upward force f4 in the figure acts on the right connecting portion L. It shows the stress distribution that occurs in the. Also in this case, the stress generated on the surface of the plate-shaped deforming portion 80 is concentrated near the connecting end of the plate-like deforming portion 80 to the connecting portion L.

In consideration of such a stress distribution, in order to detect the elastic deformation generated in the detection unit DD by the strain gauge using the detection unit DD including the plate-shaped deformation unit 80 as illustrated, the plate-shaped deformation unit 80 is used. It can be seen that effective detection is possible by arranging the strain gauges on both surfaces in the vicinity of the connection end with respect to the connecting portion L.

FIG. 47 is a side view (FIG. (a)) and a top view showing an example in which a strain gauge is used as a detection element for detecting elastic deformation generated in the detection unit DD shown in FIG. 44(c), based on such an idea. (Figure (b)). When the detection ring has a circular shape, the basic annular road B constitutes a circle, but in FIG. 47, a part of the basic annular road B is shown by a straight line for convenience of explanation.

As shown in the figure, in the plate-shaped deforming portion 80 constituting the detecting portion DD, the first strain gauge r1 is attached to the front side surface in the vicinity of the first connecting end with respect to the left side connecting portion L, and the second side is attached to the rear side surface. The strain gauge r2 is attached. Similarly, the third strain gauge r3 is attached to the front surface near the second connection end for the right connecting portion L, and the fourth strain gauge r4 is attached to the back surface.

48 is a circuit diagram showing a bridge circuit 19 that outputs an electric signal based on the detection results of the four strain gauges r1 to r4 shown in FIG. Specifically, the bridge circuit 19 has the first strain gauge r1 and the fourth strain gauge r4 as the first opposite sides, and the second strain gauge r2 and the third strain gauge r3 as the second opposite sides. It is a circuit on the opposite side and operates by applying a predetermined voltage from the bridge voltage source e. If a detection circuit for detecting the bridge voltage generated between the output terminals T5 and T6 is provided for the bridge circuit 19, the bridge voltage is modified as shown in FIG. 46(b) or shown in FIG. 46(c). It can be used as a parameter indicating the degree of deformation as shown in.

Here, although the description of the specific structure of the force sensor using the strain gauge as the detection element and the specific detection principle of each axis component is omitted, the stress distribution generated on the surface of the detection unit is measured or simulated. If it is obtained by, it is possible to determine the effective placement of the strain gauge, and by performing a predetermined calculation process based on the bridge voltage of the bridge circuit configured by these strain gauges, the detected value of the desired axial component can be obtained. It can be obtained as an electric signal.

The force sensor according to the present invention has a function of detecting a force in an arbitrary coordinate axis direction or a moment about an arbitrary coordinate axis in an XYZ three-dimensional orthogonal coordinate system. Moreover, since high production efficiency can be realized, it can be used for measuring force and moment in various industrial equipment. In particular, it is most suitable for industrial equipment that is automatically assembled using a robot arm, is incorporated in the joint part of the arm, monitors the force generated at the tip of the arm, and controls this.

11-14: C/V conversion circuits 15-18: Addition/subtraction arithmetic unit 19: Bridge circuits 61, 61B, 61C: First deforming portions 62, 62B, 62C: Second deforming portions 63, 63B, 63C: Displacement portions 64B, 64C: 1st bridge part 65B, 65C: 2nd bridge part 71, 71S: 1st deformation part 72, 72S: 2nd deformation part 73, 73S: Displacement part 80: Plate-shaped deformation part 91: 1st deformation|transformation part 92: 2nd deformation|transformation part 93: Displacement part 100: Force receiving body 150: Force receiving body 180: Force receiving body 200: Detection ring 300: Support substrate 300d: Diaphragm part 350: Fixing auxiliary body 380: Support substrates 410, 420: Connection members 460, 465: Connection members 470, 475: Connection members 480, 485: Connection members 490-495: Connection members 510, 515, 516: Fixing members 520, 525, 526: Fixing members 531 532, 532d: auxiliary connecting members 560, 570, 580, 590: fixing members 600, 600B, 600C, 600D: detection ring 600d: diaphragm parts 700, 700S: detection ring 800: detection rings A1, A2: connection reference lines B, BS: Basic loop path C, C1 to C4, C11 to C18: Capacitance element (its capacitance value)
D, D1 to D4, D11 to D18, D11S to D18S, DB, DC, DD, D1' to D4': Detection parts d1 to d8: Distances of facing surfaces E1: Fixed electrodes E11 to E18: Fixed electrodes E2, E2( D1) to E2 (D4): Displacement electrodes E21 to E28: Displacement electrode EL: Large area electrode ES: Small area electrode e: Bridge voltage source Fx: X-axis direction force Fy: Y-axis direction force Fz: Z-axis direction Force f1: compression force f2: extension force f3, f4: forces G1 and G2 in the vertical direction in the figure: groove portions H1 and H2: void portions I1 and I2: insulating layers L, L1 to L4, L11 to L18, and L11S to L18S: Connection portion Mx: Moment about X axis My: Moment about Y axis Mz: Moment about Z axis N: Normal line O: XYZ origin of three-dimensional coordinate system P1, P2, P11 to P16: Fixed point Q1, Q2, Q11 to Q16: Working points R1 to R4, R11 to R18: Detection points/measurement points r1 to r4: Strain gauges S1 to S4: Each side T1 to T6 of the rectangular detection ring 700S: Output terminals U: Vertical plane V: An axis obtained by rotating the X axis counterclockwise by 45° on the XY plane VX: Coordinate axis located between the V axis and the X axis VY: Coordinate axes V1 to V4 located between the V axis and the Y axis : Voltage W: An axis obtained by rotating the Y axis counterclockwise by 45° on the XY plane WX: Coordinate axis located in the middle of the W axis and the X axis WY: Coordinate axis X located in the middle of the W axis and the Y axis : XYZ three-dimensional coordinate system coordinate axis Y: XYZ three-dimensional coordinate system coordinate axis Z: XYZ three-dimensional coordinate system coordinate axis

Claims (8)

A force sensor that detects a force or moment about at least one of the forces in each coordinate axis direction and the moment about each coordinate axis in the XYZ three-dimensional Cartesian coordinate system, and receives a force or moment to be detected. A force body, which has a ring shape when viewed from the Z-axis direction,
A support for supporting the force receiving body,
A detection ring connected between the force receiving member and the support member, the detection unit having a portion that is elastically deformed by the action of a force or moment to be detected, And a detection ring having a detection portion having a curved structure that is curved so as to form a part of the detection ring ,
A detection element that detects elastic deformation generated in the detection unit,
A detection circuit for outputting an electric signal indicating a force or a moment acting on the other of the force receiving body and the supporting body based on the detection result of the detection element, in a state where a load is applied to one of the force receiving body and the supporting body;
Equipped with
The detection unit has a first plate-shaped piece whose one end is connected to the support, a second plate-shaped piece whose one end is connected to the force receiving body, and a first end which is the first plate-shaped piece. A third plate-like piece connected to the other end of the piece and having a second end connected to the other end of the second plate-like piece,
The detection element includes a displacement electrode fixed at a predetermined position of the third plate-like piece, and a fixed electrode fixed at a position facing the displacement electrode of the supporting body or the force receiving body. Composed of elements,
The force sensor, wherein the detection circuit outputs an electric signal indicating an applied force or moment based on a change in the capacitance value of the capacitive element. The force sensor according to claim 1,
The force sensor, wherein the first plate-shaped piece and the second plate-shaped piece extend in mutually different directions when viewed in a radial direction orthogonal to the Z-axis direction. The force sensor according to claim 1 or 2,
The force sensor, wherein the first plate-shaped piece and the third plate-shaped piece extend in mutually different directions when viewed in a radial direction orthogonal to the Z-axis direction. The force sensor according to any one of claims 1 to 3,
The force sensor, wherein the second plate-shaped piece and the third plate-shaped piece extend in mutually different directions when viewed in a radial direction orthogonal to the Z-axis direction. The force sensor according to any one of claims 1 to 4,
That the first plate-shaped piece, the second plate-shaped piece, and the third plate-shaped piece extend in different directions when viewed in a radial direction orthogonal to the Z-axis direction. Characteristic force sensor. The force sensor according to any one of claims 1 to 5,
A force sensor, wherein the length of the third plate-shaped piece is longer than the length of the displacement electrode when viewed in a radial direction orthogonal to the Z-axis direction. The force sensor according to any one of claims 1 to 6,
The force sensor, wherein the displacement electrode is fixed to a flat surface of the third plate-shaped piece. The force sensor according to any one of claims 1 to 7,
The force sensor, wherein the third plate-shaped piece has the curved structure.

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