JP6910693B2 - 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 around each coordinate axis in a three-dimensional Cartesian coordinate system.

Various types of force sensors are used to control the movement of robots and industrial machines. A small force sensor is also incorporated as a man-machine interface for the input device of electronic devices. In order to reduce the size and cost of the force sensor used for such applications, the structure should be as simple as possible, and the force related to each coordinate axis in the three-dimensional space should be detected independently. Is required.

Currently, multiaxial force sensors that are generally used are of the type that detects a specific directional component of the force acting on the mechanical structure as a displacement that occurs in a specific part, and those that occur in a specific part. It is classified as a type that is detected as mechanical distortion. A typical example of the former displacement detection type is a capacitive element type force sensor. A capacitive element is composed of a pair of electrodes, and the displacement generated on one electrode by the applied force is applied to the capacitive element. It is detected based on the capacitance value. For example, the following Patent Document 1 (the English version thereof is Patent Document 2) and Patent Document 3 (the English version thereof is Patent Document 4) disclose this capacitive multiaxial force sensor.

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

However, in each of the multiaxial force sense sensors disclosed in the above-mentioned patent documents, the thickness of the mechanical structure portion has to be increased, 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, etc., the appearance of thinner force sensors is desired. Therefore, Patent Document 7 proposes a force sensor that deforms the shape of an annular member by the action of a force and detects the displacement of each part caused by this deformation by a capacitive element. The force sensor disclosed in Patent Document 7 (referred to as a prior force sensor in the present application) has a structure suitable for simplifying and thinning the structure.

Japanese Unexamined Patent Publication No. 2004-325376 U.S. Pat. No. 7219561 Japanese Unexamined Patent Publication No. 2004-354049 U.S. Pat. No. 6,915,709 Japanese Unexamined Patent Publication No. 8-122178 U.S. Pat. No. 5,490,427 International Publication No. WO 2013/014803

However, in the above-mentioned prior force sensor, it is necessary to arrange the capacitive elements at various places in order to detect various deformation modes of the annular member, so that the electrode configuration constituting the capacitive element is not complicated. Do not get. Moreover, since the relative positions of the pair of electrodes constituting the capacitive element are important factors that affect the detection accuracy, a great work load is required for adjusting the positions of the individual electrodes. In particular, when a plurality of capacitive elements are arranged with symmetry and difference detection is performed using these, the counter electrodes are parallel to each capacitive element and the electrode spacing for the plurality of capacitive elements is set. Need to be adjusted so that they are equal to each other. Therefore, for commercial use, there is a problem that the production efficiency is lowered and the cost is soared.

Therefore, an object of the present invention is to provide a force sensor that has a simple structure and can realize high production efficiency by improving the degree of freedom in arranging detection elements.

(1) A first aspect of the present invention is a force sensor that detects a force or moment related to at least one of the force in each coordinate axis direction and the moment around each coordinate axis in the XYZ three-dimensional Cartesian coordinate system.
A receiving body that is affected by a force or moment to be detected,
A detection ring having an annular structure extending along a predetermined basic ring road, having a detection unit located at a detection point defined on the basic ring road, and connecting portions located on both sides of the detection unit.
A support that supports the detection ring and
A connecting member that connects the receiving body to the position of a predetermined point of action of the detection ring,
A fixing member that fixes the position of a predetermined fixing point of the detection ring to the support,
A detection element that detects elastic deformation that occurs in the detection unit,
Based on the detection result of the detection element, a detection circuit that outputs an electric signal indicating the force or moment acting on one of the receiving body and the support while the load is applied to the other, and a detection circuit.
Provided
The points of action and fixed points are located at different positions on the connection.
The detection unit has a structure in which at least a part of the detection unit causes elastic deformation based on the applied force when a force is applied between the point of action and the fixed point.

(2) A second aspect of the present invention is the force sensor according to the first aspect described above.
The detection element is composed of 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 receiving body.
The displacement electrode is arranged at a position where the displacement is generated 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 acting force or moment based on the fluctuation of the capacitance value of the capacitive element.

(3) A third aspect of the present invention is the force sensor according to the second aspect described above.
When the XY plane is a horizontal plane and the Z axis is a vertically upward axis,
The detection ring has an annular structure extending along a basic annular road located in the XY plane with the Z axis as the central axis.
The support is composed of support substrates arranged below the detection ring at predetermined intervals.
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 third aspect described above.
The first deformation part in which the detection part causes elastic deformation by the action of the force or moment to be detected, the second deformation part in which the detection part causes elastic deformation by the action of the force or moment to be detected, and the first deformation. It has a portion and a displacement portion that causes displacement due to elastic deformation of the second deformed portion.
The outer end of the first deformed portion is connected to a connecting portion adjacent thereto, the inner end of the first deformed portion is connected to the displacement portion, and the outer end of the second deformed portion is connected to the connecting portion adjacent thereto. Connected, the inner end of the second deformed part is connected to the displacement part,
The displacement electrode is fixed at a position facing the support substrate of the displacement portion.

(5) A fifth aspect of the present invention is the force sensor according to the fourth aspect described above.
A plurality of n (n ≧ 2) detection points are defined on the basic ring road, detection units are located at each detection point, and a detection ring connects n detection parts and n connection parts. It is configured by being arranged alternately 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 of n (n ≧ 2) detection points are defined on the basic ring road, detection units are located at each detection point, and a detection ring connects n detection units and n connection parts. It is configured by being arranged alternately 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 even n connecting parts are numbered in order along the basic ring road, the points of action are arranged at the odd-numbered connecting parts and the fixed points are arranged at the even-numbered connecting parts. It is the one that was made.

(8) An eighth aspect of the present invention is the force sensor according to the seventh aspect described above.
By setting n = 2, the detection ring is arranged 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 ring road. Is configured, the point of action is arranged in the first connecting portion, and the fixed point is arranged in 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, along the basic ring road, the first connecting part, the first detecting part, the second connecting part, the second detecting part, the third connecting part, and the third detection A detection ring is configured by arranging a portion, a fourth connecting portion, and a fourth detecting portion in this order, a first point of action is arranged on the first connecting portion, and a first fixed point. Is placed in the second connecting part, the second point of action is placed in the third connecting part, the second fixed point is placed in the fourth connecting part, and so on.
The connecting member connects the position of the first point of action of the detection ring to the receiving body and the second connecting member connecting the position of the second point of action of the detection ring to the receiving body. And have
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. It is intended to have.

(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. Is arranged on the negative Y-axis.

(11) The eleventh aspect of the present invention is the force sensor according to the tenth aspect described above.
In the XY plane, the V axis is defined as the coordinate axis obtained by rotating the X axis counterclockwise by 45 ° around the origin O, and the W axis is defined as the coordinate axis obtained by rotating the Y axis counterclockwise by 45 ° around the origin O. Is defined, 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 negative. 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.
Capacitive elements are formed in each detection unit so that the increase and decrease of the capacitance value is reversed when compressive stress is applied and when tensile stress is applied along the basic ring road.
The capacitance value of the first capacitive element having the displacement electrode fixed to the first detection unit located at the first detection point is fixed to C1 and the second detection unit 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 unit located at the third detection point is set to C2. C3, when the capacitance value of the fourth capacitive element having the displacement electrode fixed to the fourth detection unit 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 above formula, 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 shown. 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 part, the first detecting part, the second connecting part, the second detecting part, the third connecting part, and the third detection along the basic ring road. Unit, 4th connecting part, 4th detecting part, 5th connecting part, 5th detecting part, 6th connecting part, 6th detecting part, 7th connecting part, 7th detecting part, The detection ring is configured by arranging the eighth connecting portion and the eighth detecting portion in this order.
The first point of action is located at the first connecting point, the first fixed point is located at the second connecting point, the second point of action is located at the third connecting point, and the second fixed point. Is placed in the fourth connecting part, the third point of action is placed in the fifth connecting part, the third fixed point is placed in the sixth connecting part, and the fourth point of action is placed in the seventh connecting part. Placed in the section, the fourth fixed point is placed in the eighth connecting section,
The connecting member connects the position of the first point of action of the detection ring to the receiving body and the second connecting member connecting the position of the second point of action of the detection ring to the receiving body. A third connecting member that connects the position of the third point of action of the detection ring to the receiving body, and a fourth connecting member that connects the position of the fourth point of action of the detection ring to the receiving body. Have,
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. To have a third fixing member that fixes the position of the third fixing point of the detection ring to the support substrate and a fourth fixing member that fixes 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.
In the XY plane, the V axis is defined as the coordinate axis obtained by rotating the X axis counterclockwise by 45 ° around the origin O, and the W axis is defined as the coordinate axis obtained by rotating the Y axis counterclockwise by 45 ° around 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, the fourth point of action is on the negative Y-axis, the first The fixed point is on the positive V-axis, the second fixed point is on the positive W-axis, the third fixed point is on the negative V-axis, and the fourth fixed point is on the negative W-axis. It is something like that.

(15) A fifteenth aspect of the present invention is the force sensor according to the fourteenth aspect described above.
In the XY plane, when the directional vector Vec (θ) forming an angle θ counterclockwise with respect to the positive direction of the X axis is defined with the origin O as the starting point, the i-th (however, 1 ≦ i ≦ 8) The detection points are arranged at the intersections of the directional vector Vec (π / 8 + (i-1) · π / 4) and the basic loop path.

(16) A sixteenth aspect of the present invention is the force sensor according to the fifteenth aspect described above.
Capacitive elements are formed in each detection unit so that the increase and decrease of the capacitance value is reversed when compressive stress is applied and when tensile stress is applied along the basic ring road.
When the capacitance value of the i-th capacitive element having the displacement electrode fixed to the i-th detection unit 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
Calculation formula,
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
Alternatively, Fy = -C15 + C16 + C17-C18
Calculation formula,
Regarding the force Fz acting in the Z-axis direction,
Fz =-(C11 + C12 + C13 + C14 + C15 + C16 + C17 + C18) or Fz =-(C11 + C14 + C15 + C18)
Alternatively, Fz =-(C12 + C13 + C16 + C17)
Calculation formula,
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
Calculation formula,
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
Calculation formula,
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
Calculation formula,
By performing the calculation based on the above, an electric signal indicating the force Fx, the force Fy, the force Fz, the moment Mx, the moment My, and the moment Mz is output.

(17) A seventeenth aspect of the present invention is the force sensor according to the sixth aspect described above.
When an even number of n connecting parts are numbered in order along the basic ring road, the point of action and the fixed point are both at the odd-numbered connecting part, and the point of action and the fixed point are basically. They are arranged so as to alternate along the ring 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 part, the first detecting part, the second connecting part, the second detecting part, the third connecting part, and the third detection along the basic ring road. Unit, 4th connecting part, 4th detecting part, 5th connecting part, 5th detecting part, 6th connecting part, 6th detecting part, 7th connecting part, 7th detecting part, The detection ring is configured by arranging the eighth connecting portion and the eighth detecting portion in this order.
The first fixed point is arranged in the first connecting part, the first point of action is arranged in the third connecting part, the second fixed point is arranged in the fifth connecting part, and the second point of action is arranged. Is placed at the 7th connecting part,
The connecting member connects the position of the first point of action of the detection ring to the receiving body and the second connecting member connecting the position of the second point of action of the detection ring to the receiving body. And have
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. It is made 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 point of action is located on the positive Y-axis, and the second point of action. Is 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 arranged in the XY plane with the origin O as the center, and has a first side extending in a direction parallel to the Y axis and intersecting the positive X axis, and a direction parallel to the X axis. The second side intersects the positive Y-axis, the third side intersects the negative X-axis extending in the direction parallel to the Y-axis, and intersects the negative Y-axis extending in the direction parallel to the X-axis. Has a fourth side and
The first detection point is placed at a position having the positive Y coordinate of the first side, the second detection point is placed at the position having the positive X coordinate of the second side, and the third detection. A point is placed at a position having a negative X coordinate on the second side, a fourth detection point is placed at a position having a positive Y coordinate on the third side, and a fifth detection point is a fifth. The third side is placed at a position with a negative Y coordinate, the sixth detection point is placed at a position with a negative X coordinate on the fourth side, and the seventh detection point is on the 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 of the first side.

(21) The 21st aspect of the present invention is the force sensor according to the 20th aspect described above.
Capacitive elements are formed in each detection unit so that the increase and decrease of the capacitance value is reversed when compressive stress is applied and when tensile stress is applied along the basic ring road.
When the capacitance value of the i-th capacitive element having the displacement electrode fixed to the i-th detection unit 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
Calculation formula,
Regarding the force Fy acting in the Y-axis direction,
Fy = -C11-C14 + C15 + C18
Calculation formula,
Regarding the force Fz acting in the Z-axis direction,
Fz =-(C11 + C12 + C13 + C14 + C15 + C16 + C17 + C18) or Fz =-(C11 + C13 + C15 + C17)
Alternatively, Fz =-(C12 + C14 + C16 + C18)
Calculation formula,
Regarding the moment Mx acting around the X axis,
Mx = -C11-C12-C13-C14 + C15 + C16 + C17 + C18
Alternatively, Mx = -C12-C13 + C16 + C17
Calculation formula,
Regarding the moment My acting around the Y axis,
My = + C11 + C12-C13-C14-C15-C16 + C17 + C18
Alternatively, My = + C11-C14-C15 + C18
Calculation formula,
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
Calculation formula,
By performing the calculation based on the above, an electric signal indicating the force Fx, the force Fy, the force Fz, the moment Mx, the moment My, and the moment Mz is output.

(22) The 22nd aspect of the present invention is the force sensor according to the 19th aspect described above.
The detection ring is a circular annular structure arranged in the XY plane with the origin O as the center.
In the XY plane, when the directional vector Vec (θ) forming an angle θ counterclockwise with respect to the positive direction of the X axis is defined with the origin O as the starting point, the i-th (however, 1 ≦ i ≦ 8) The detection points are arranged at the intersections of the directional vector Vec (π / 8 + (i-1) · π / 4) and the basic loop path.

(23) The 23rd aspect of the present invention is the force sensor according to the 5th to 22nd aspects described above.
Regarding the force or moment about the specific axis to be detected, some of the n plurality of detectors behave as the first attribute detector, and the other part behaves as the second attribute detector.
The first attribute displacement part constituting the first attribute detection part is displaced in the direction approaching the support substrate when the positive component for the specific axis acts, and the negative component for the specific axis acts. When it is displaced, it is displaced in the direction away from the support board,
The second attribute displacement part constituting the second attribute detection part is displaced in the direction away from the support substrate when the positive component for the specific axis acts, and the negative component for the specific axis acts. When it is displaced, it is displaced toward the support substrate,
The first attribute capacitance element is composed of the first attribute displacement electrode fixed to the first attribute displacement portion and the first attribute fixed electrode fixed at a position facing the first attribute displacement electrode of the support substrate.
The second attribute capacitance element is composed of the second attribute displacement electrode fixed to the second attribute displacement portion and the second attribute fixed electrode fixed at a position facing the second attribute displacement electrode of the support substrate.
The detection circuit transmits an electric signal corresponding to the difference between the capacitance value of the first attribute capacitance element and the capacitance value of the second attribute capacitance element with respect to the specific axis of the force or moment to be detected. It is designed to be output as an electric signal indicating the components of.

(24) The 24th aspect of the present invention is the force sensor according to the 4th to 23rd aspects described above.
The detection ring is obtained by partially removing the material from the annular member obtained by forming a through opening in the central portion of the plate-shaped member arranged with the Z axis as the central axis. It is a member that has been subjected to this material removal process so that the detection unit is composed of the portion.

(25) The 25th aspect of the present invention is the force sensor according to the 4th to 24th aspects described above.
A detection unit having a first deformed portion, a second deformed portion, and a displacement portion is arranged between one connecting portion end portion and the other connecting portion end portion.
The first deformed portion is composed of a first plate-shaped piece having flexibility, the second deformed portion is composed of a second plate-shaped piece having flexibility, and the displacement portion is a third. Consists of plate-shaped 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 the second plate-shaped piece is connected to the other end of the 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) The 26th aspect of the present invention is the force sensor according to the 25th aspect described above.
In a state where no force or moment is applied, the facing surface of the third plate-shaped piece and the facing surface of the support substrate are maintained in parallel.

(27) A 27th aspect of the present invention is the force sensor according to the 26th aspect described above.
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 constituting the detection unit located at the detection point are inclined with respect to the normal line. In addition, the tilting direction of the first plate-shaped piece and the tilting direction of the second plate-shaped piece are opposite to each other.

(28) The 28th aspect of the present invention is the force sensor according to the 3rd to 27th aspects described above.
When a connection reference line parallel to the Z axis is defined through the action point or the movement point where the action point is moved along the line connecting the origin O of the coordinate system and the action point, the connection reference line or its Along the vicinity, an auxiliary connecting member for connecting the lower surface of the detection ring or the receiving body and the upper surface of the support substrate is further provided.

(29) The 29th aspect of the present invention is the force sensor according to the 28th aspect described above.
As the auxiliary connection member, a member that is more likely to undergo elastic deformation when a force is applied in a direction orthogonal to the connection reference line is used than when a force is applied in a direction along the connection reference line. It is a thing.

(30) A thirtieth aspect of the present invention is the force sensor according to the 28th or 29th aspect described above.
The connection portion of the detection ring or the receiving body to the auxiliary connecting member, the connecting portion of the support substrate to the auxiliary connecting member, or both of these connecting portions are formed by a diaphragm portion, and the diaphragm portion is based on the action of a force or a moment. The auxiliary connecting member is tilted with respect to the connection reference line due to the deformation of.

(31) The 31st aspect of the present invention is the force sensor according to the 2nd to 30th aspects described above.
One of the fixed electrode and the displacement electrode so that the effective facing area of the pair of electrodes constituting the capacitive element does not change even when the displacement electrode is translated with respect to the fixed electrode as a result of the action of a force or moment. The area of is set larger than the area of the other.

(32) The 32nd aspect of the present invention is the force sensor according to the 2nd to 31st aspects described above.
The detection ring, the support, and the receiving body 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 the receiving body. It is made to be formed through layers.

(33) The 33rd aspect of the present invention is the force sensor according to the 2nd to 32nd aspects described above.
The detection ring, the support, and the receiving body are made of a conductive material, and a displacement electrode is formed by a part of the surface of the detection ring, or a part of the surface of the support or the receiving body. The fixed electrode is configured by the region.

(34) A thirty-fourth aspect of the present invention is the force sensor according to the first aspect described above.
The detection element is composed of a strain gauge fixed at a position where elastic deformation of the detection unit occurs.
The detection circuit outputs an electric signal indicating the acting force or moment based on the fluctuation of the electric resistance of the strain gauge.

(35) The 35th aspect of the present invention is the force sensor according to the 34th aspect described above.
It seems that the detection part has a plate-like deformation part that causes elastic deformation by the action of a force or moment to be detected, and the plate-like deformation part is arranged so that the plate surface is inclined with respect to the basic ring road. It is the one that was made.

(36) The 36th aspect of the present invention is the force sensor according to the 35th aspect described above.
The detection element is configured by strain gauges arranged on both sides in the vicinity of the connection end of the plate-shaped deformed portion with respect to the connecting portion.

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

(38) A 38th aspect of the present invention is the force sensor according to the 1st to 19th and 34th to 37th aspects described above.
The detection ring is an annular structure having a circle arranged on the XY plane with the Z axis as the central axis as the basic annular path.
The support is a circular plate-like structure or an annular structure arranged in the Z-axis negative region with the Z-axis as the central axis.
The receiving body is a circular plate-like structure or an annular structure arranged in the Z-axis positive region with the Z-axis as the central axis, or a circular plate-like structure or an annular structure arranged in the XY plane with the Z-axis as the central axis. It is made to be an annular structure.

(39) A 39th aspect of the present invention is the force sensor according to the 1st to 19th and 34th to 37th aspects described above.
The detection ring is an annular structure having a square as a basic annular path arranged in 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 receiving body is a square plate-like structure or an annular structure arranged in the Z-axis positive region with the Z-axis as the central axis, or a square plate-like structure or an annular structure arranged in the XY plane with the Z-axis as the central axis. It is made to be an annular structure.

(40) The 40th aspect of the present invention is the force sensor according to the 1st to 39th aspects described above.
The receiving body is an annular structure capable of accommodating the detection ring inside, and the receiving body is arranged outside the detection ring.

(41) The 41st aspect of the present invention is the force sensor according to the 1st to 39th aspects described above.
The detection ring is an annular structure capable of accommodating the receiving body inside, and the receiving body is arranged inside the detection ring.

(42) A 42nd aspect of the present invention is the force sensor according to the 1st to 39th aspects described above.
When the XY plane is a horizontal plane and the Z axis is an axis vertically upward, the detection ring is arranged on the XY plane, the supports are arranged below the detection ring at predetermined intervals, and the receiving body is the detection ring. It is arranged above the above at a predetermined interval.

In the force sensor according to the present invention, the acting force and moment are detected based on the deformation mode of the detection ring having an annular structure. This detection ring has a detection unit that causes elastic deformation and connecting portions located on both sides of the detection unit, and when a force or moment to be detected acts on the detection unit, the detection unit is intensively elastically deformed. 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, the degree of freedom in arranging the detection elements can be improved, and it becomes possible to provide a force sensor capable of achieving high production efficiency.

When electrically detecting the displacement based on the elastic deformation of the detection unit, a capacitive element can be adopted 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 formation surface of the displacement electrode on the detection ring side can be freely set, effective design can be performed in order to improve production efficiency. In addition, when a force in a specific coordinate axis direction or a moment around a specific coordinate axis acts, it is possible to design a part of the detection unit to be displaced in a specific direction, so that the force or moment to be detected can be detected. A force sensor that efficiently detects an arbitrary directional component can be designed.

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

It is a top view (upper view) and a side view (lower view) of the basic structure part of the prior application force sensor. It is a cross-sectional view (upper view) of the basic structural portion shown in FIG. 1 cut in the XY plane and a vertical cross-sectional view (lower view) cut in the XZ plane. It is a top view (upper view) of the support substrate 300 and the fixing members 510 and 520 of the basic structure part shown in FIG. 1, and a vertical cross-sectional view (lower view) of the basic structure part cut in a YZ plane. A cross-sectional view in the XY plane (upper view) and a vertical cross-sectional view in the XZ plane (lower) showing the deformation state when a force + Fx in the positive direction of the X axis is applied to the receiving body 100 of the basic structure shown in FIG. Figure). It is a vertical cross-sectional view in the XZ plane which shows the deformation state when the force + Fz in the Z-axis positive direction is applied to the receiving body 100 of the basic structure part shown in FIG. It is a vertical cross-sectional view in the XZ plane which shows the deformation state when the moment + My about the positive direction of the Y axis acts on the receiving body 100 of the basic structure part shown in FIG. FIG. 5 is a cross-sectional view on an XY plane showing a deformed state when a moment + Mz around the Z-axis is applied to a receiving body 100 of the basic structural portion shown in FIG. It is a top view (upper view) and side view (lower view) showing an embodiment in which a fixing auxiliary body 350 for displacement detection is added to the basic structure portion shown in FIG. 1. It is a cross-sectional view (upper view) of the basic structural portion shown in FIG. 8 cut in the XY plane and a vertical cross-sectional view (lower view) cut in the VZ plane. It is a top view which shows the distance measurement part in the basic structure part shown in FIG. It is a table which shows the change of the distance d1 to d8 when the force in each coordinate axis direction and the moment around each coordinate axis act on the basic structure part shown in FIG. The force sensor configured by adding a capacitance element to the basic structure shown in FIG. 9 is shown in a cross-sectional view (upper view) cut in the XY plane and a vertical cross-sectional view (lower view) cut in the VZ plane. be. It is a perspective view (FIG. (A)), a side view (FIG. (B)), and a bottom view (FIG. (C)) of the detection ring 600 used for the force sensor according to the 1st Embodiment of this invention. It is a top view which shows the region distribution of the detection ring 600 shown in FIG. 13 (the mesh-like hatching is for showing the region of detection part D1 to D4, and does not show the cross section). It is a top view which shows the basic ring road B defined on the XY plane and each point defined on this basic ring road B about the detection ring 600 shown in FIG. It is the top view (upper view) of the basic structure part of the force sensor which concerns on 1st Embodiment of this invention, and the side sectional view (lower figure) which cut it in the XZ plane. FIG. 3 is a partial cross-sectional view showing a detailed structure of detection units D1 to D4 (representatively indicated by reference numerals D) of the detection ring 600 shown in FIG. FIG. 3 is a partial cross-sectional view showing a detailed structure in which electrodes are provided in predetermined portions of detection portions D1 to D4 (representatively indicated by reference numeral D) of the detection ring 600 shown in FIG. 13 and a support substrate 300 facing the detection portions D1 to D4. It is a figure which shows the principle of keeping the effective area of a capacitive element constant even when the relative position of a displacement electrode with respect to a fixed electrode changes. The amount of change (degree of increase / decrease) in the capacitance value of each capacitive element when a force in each axial direction or a moment around each axis is applied to the receiving body 100 according to the first embodiment shown in FIG. It is a table. It is a table obtained by approximately replacing the columns (−) and (+) in the table shown in FIG. 20 with zeros. It is a figure which shows the arithmetic expression which calculates the 4-axis component of the force Fz and the moment Mx, My, Mz acting on the receiving body 100 in 1st Embodiment shown in FIG. 16 based on the table shown in FIG. It is a circuit diagram which shows an example of the detection circuit which outputs the electric signal which shows the 4-axis component of a force Fz and a moment Mx, My, Mz based on the arithmetic expression shown in FIG. It is a bottom view of the detection ring 700 used for the force sensor which concerns on the 2nd Embodiment of this invention. It is a top view which shows the region distribution of the detection ring 700 shown in FIG. 24 (the mesh-like hatching is for showing the region of detection part D11 D18, and does not show the cross section). It is a top view which shows the basic ring road B defined at the position on the XY plane of the detection ring 700 shown in FIG. 24, and each point defined on this basic ring road B. It is a top view of the basic structure part of the force sensor which concerns on 2nd Embodiment of this invention. The amount of change (degree of increase / decrease) in the capacitance value of each capacitive element when a force in each axial direction or a moment around each axis is applied to the receiving body 100 in the second embodiment shown in FIG. 27 is shown. It is a table. Based on the table shown in FIG. 28, an arithmetic formula for calculating the six-axis components of the forces Fx, Fy, Fz and the moments Mx, My, Mz acting on the receiving body 100 in the second embodiment shown in FIG. 27 is shown. It is a figure. It is a figure which shows the variation of the arithmetic expression shown in FIG. It is a bottom view (upper view) of the basic structure part of the force sensor according to the third embodiment of the present invention, and a side sectional view (lower view) obtained by cutting the basic structure portion in the XZ plane. The amount of change (degree of increase / decrease) in the capacitance value of each capacitive element when a force in each axial direction or a moment around each axis is applied to the receiving body 100 in the third embodiment shown in FIG. 31 is shown. It is a table. It is a partial side sectional view which shows the modification about the attachment part of the auxiliary connection member 532 in 3rd Embodiment shown in FIG. When a force in each axial direction or a moment around each axis acts on the 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. 31 It is a table which shows the fluctuation amount (the degree of increase / decrease) of the capacitance value of a capacitive element. It is a top view of the square detection ring 700S used for the force sensor which concerns on 4th Embodiment of this invention. It is a top view which shows the region distribution of the detection ring 700S shown in FIG. 35 (the mesh-like hatching is for showing the region of detection part D11S to D18S, and does not show the cross section). It is a top view which shows the basic ring road BS defined at the position on the XY plane of the detection ring 700S shown in FIG. 35, and each point defined on this basic ring road BS. A table showing the amount of change (degree of increase / decrease) in the capacitance value of each capacitive element when a force in each axial direction or a moment around each axis acts on the receiving body according to the fourth embodiment shown in FIG. 35. Is. Based on the table shown in FIG. 38, a diagram showing an arithmetic formula for calculating the six-axis components of the forces Fx, Fy, Fz and the moments Mx, My, Mz acting on the receiving body in the fourth embodiment shown in FIG. 35. Is. It is a figure which shows the 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 5th Embodiment of this invention. It is a top view (upper view) of the basic structure part of the force sensor according to the sixth embodiment of the present invention, and a side sectional view (lower view) obtained by cutting the basic structure portion in the XZ plane. It is the top view (upper view) of the basic structure part of the force sensor which concerns on 7th Embodiment of this invention, and the side sectional view (lower figure) which cut it in the XZ plane. It is a partial cross-sectional view which shows the variation of the structure of the detection part in this invention. Top view (upper view) of the basic structural part of the force sensor according to the modified example in which the detection ring 800 in which the direction of the detection part is changed is used instead of the detection ring 600 in the first embodiment shown in FIG. It is a side sectional view (lower view) which cut this in the XZ plane. FIG. 44 (c) is a partial cross-sectional view showing an mode of elastic deformation of the plate-shaped deformed portion 80 constituting the detection portion DD shown in FIG. 44 (c). FIG. 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 the electric signal based on the detection result of 4 sets of strain gauges shown in FIG. 47.

Hereinafter, the present invention will be described based on the illustrated embodiment. It should be noted that the present invention is an improved invention of the prior application force sensor disclosed in Patent Document 7 (International Publication No. WO 2013/014803) described above. Therefore, for convenience of explanation, first, the prior application force sensor will be described in §1 and §2 below, and the features of the present invention will be described in §3 and subsequent sections.

<<< §1. Features of the basic structure of the first-to-file force sensor >>>
FIG. 1 is a top view (upper view) and a side view (lower view) of the basic structure of the 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 paper surface is the Z-axis direction. On the other hand, in the side view, the X-axis is arranged in the right direction of the figure and the Z-axis is arranged in the upper direction 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 part is composed of a receiving body 100, a detection ring 200, a support substrate 300, connecting members 410, 420, and fixing members 510, 520.

The receiving body 100 is a circular flat plate-shaped (washer-shaped) ring arranged on an XY plane so 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 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, the detection ring 200 is a circular flat plate-shaped (washer-shaped) ring arranged on the XY plane so that the Z axis is the central axis, like the receiving body 100, and has both an outer peripheral surface and an inner peripheral surface. It constitutes a cylindrical surface. In the case of the example shown here, the detection ring 200 is arranged inside the receiving body 100. That is, the receiving body 100 is an outer ring arranged on the XY plane, and the detection ring 200 is an 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 connecting members 410 and 420 are members for connecting the receiving body 100 and the detection ring 200. In the case of the illustrated example, the connecting member 410 connects the inner peripheral surface of the receiving body 100 and the outer peripheral surface of the detection ring 200 at a position along the X-axis positive region, and the connecting member 420 connects the X-axis negative region. The inner peripheral surface of the receiving body 100 and the outer peripheral surface of the detection ring 200 are connected at a position along the above. Therefore, a gap H1 is secured between the 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 figure.

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

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

FIG. 2 is a cross-sectional view (upper view) of the basic structural portion shown in FIG. 1 cut in the XY plane and a vertical cross-sectional view (lower view) cut in the XZ plane. The origin O of the XYZ three-dimensional Cartesian coordinate system is shown at the center of the cross-sectional view cut along the XY plane. In FIG. 2, the state in which the detection ring 200 is connected to the receiving body 100 via the connecting members 410 and 420 arranged along the X axis at two positions on the left and right 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 cut along a 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 indicated by a broken line. On the other hand, the vertical cross-sectional view of FIG. 3 clearly shows the state in which the detection ring 200 is fixed above the support substrate 300 by the fixing members 510 and 520.

As will be described later, when forces in various directions act on the receiving body 100 in a state where the support substrate 300 is fixed, the detection ring 200 is deformed in a manner corresponding to the applied force. The prior force sensor detects the applied force by electrically detecting this deformation mode. Therefore, the ease of elastic deformation of the detection ring 200 is a parameter that affects the detection sensitivity of the sensor. By using the detection ring 200 that is easily elastically deformed, it is possible to realize a sensor with high sensitivity that can detect even when a minute force is applied, but the maximum value of the detectable force is suppressed. On the contrary, if the detection ring 200 which is hard to be elastically deformed is used, the maximum value of the detectable force can be taken large, but the sensitivity is lowered, so that the minute force cannot be detected.

The ease of elastic deformation of the detection ring 200 is determined depending on the thickness in the Z-axis direction and the thickness in the radial direction (the thinner the both, the easier the elastic deformation is), and further depends on the material thereof. Therefore, in practice, it is necessary to select the dimensions and materials 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 has been improved in this respect, and the degree of freedom in design can be further improved according to the industrial demand.

On the other hand, the receiving body 100 and the supporting substrate 300 do not need to be members that cause elastic deformation in principle of detecting the force. Rather, it is preferable that the receiving body 100 and the supporting substrate 300 are completely rigid bodies so that the applied force contributes 100% to the deformation of the detection ring 200. In the illustrated example, the reason for using the ring-shaped structure having the gap H1 in the center as the receiving body 100 is not to facilitate elastic deformation but to accommodate the detection ring 200 inside. As shown in the illustrated example, if the ring-shaped receiving body 100 is arranged outside the detection ring 200, the thickness of the basic structural portion can be reduced, and a thinner force sensor can be realized.

Practically, as the material of the receiving body 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. It is sufficient to use a metal such as stainless steel or aluminum. Of course, a combination of an insulating material and a conductive material may be used.

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

As described above, the receiving body 100 and the supporting substrate 300 are originally preferably completely rigid bodies so that the applied force contributes 100% to the deformation of the detection ring 200. However, in reality, when the basic structural part is made of resin or metal, the receiving body 100 and the supporting substrate 300 are not completely rigid, and it can be said strictly that a force or a moment is applied to the receiving body 100. For example, the receiving body 100 and the supporting substrate 300 are also slightly elastically deformed. However, if the elastic deformation that occurs in the receiving body 100 and the support substrate 300 is slightly more elastic than the elastic deformation that occurs in the detection ring 200, it can be ignored, and there is no problem in considering it as a substantially rigid body. Therefore, in the present application, it is assumed that the receiving body 100 and the supporting substrate 300 are rigid bodies, and elastic deformation due to a force or a moment occurs exclusively in the detection ring 200.

First, let us consider what kind of change occurs in this basic structural portion when a force in the X-axis direction acts on the receiving body 100 in a state where the support substrate 300 is fixed. FIG. 4 is a cross-sectional view (upper view) in the XY plane and a vertical cross section in the XZ plane showing a deformed state when a force + Fx in the positive direction of the X axis is applied to the receiving body 100 of the basic structure shown in FIG. It is a figure (lower figure). Since the support substrate 300 is fixed, it is immobile, but the 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 is deformed as shown. The broken line shown in the figure indicates the position of each ring before movement or deformation.

Here, for convenience of explaining this modification, two fixed points P1 and P2 (indicated by black circles) and two points of action Q1 and Q2 (indicated by white circles) are 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 points of action Q1 and Q2 are points defined on the X-axis, and the detection ring 200 is connected to the receiving body 100 by the connecting members 410 and 420 at the positions of the points of action Q1 and Q2. ..

As described above, in the prior force sensor, the point of action is the position where the connecting member is connected, and the fixed point is the position where the fixing member is connected. And the important point is that the point of action 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 when the point of action and the fixed point occupy the same position, elastic deformation does not occur in the detection ring 200.

When a force + Fx in the positive direction of the X-axis acts on the receiving body 100, as shown in FIG. 4, a force in the right direction of the figure is applied to the action points Q1 and Q2 (white circles) of the detection ring 200. 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 shown in the figure. (Note that the figure showing the deformed state in the present application is a slightly deformed figure for emphasizing the deformed state, and is not necessarily a figure showing an accurate deformation mode). Specifically, as shown in the figure, between points P1-Q1 and points P2-Q1, a tensile force acts on both ends of the quadrant arc of the detection ring 200, causing the quadrant arc to shrink inward and points P1-Q2. Between the interval and the points P2-Q2, a pressing force acts on both ends of the quadrant arc of the detection ring 200, and the quadrant arc bulges outward.

When a force −Fx in the negative direction of the X axis acts on the receiving body 100, a phenomenon opposite to that in FIG. 4 occurs. Further, when a force + Fy in the positive direction of the Y axis and a force −Fy in the negative direction of the Y axis act on the receiving body 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 structural portion when a force in the Z-axis direction acts on the receiving body 100 in a state where the support substrate 300 is fixed. FIG. 5 is a vertical cross-sectional view in the XZ plane showing a deformed state when a force + Fz in the positive direction of the Z axis is applied to the receiving body 100 of the basic structure shown in FIG. Since the support substrate 300 is fixed, it is immovable, but the receiving body 100 moves upward in the figure by the force + Fz in the positive direction of the Z axis. As a result, the detection ring 200 is deformed as shown. The broken line shown in the figure indicates the position of each ring before movement or deformation.

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

Next, let us consider what kind of change occurs in this basic structural portion when a moment around the Y axis acts on the receiving body 100 in a state where the support substrate 300 is fixed. FIG. 6 is a vertical cross-sectional view on an XZ plane showing a deformed state when a moment + My in the positive direction of the Y axis acts on the 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 defined as the direction of rotation of the right-hand screw for advancing the right-hand 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-hand screw in the positive direction of the Y axis.

In this case as well, the support substrate 300 is immobile because it is fixed, but the receiving body 100 receives a moment + My in the positive direction of the Y axis and rotates clockwise around the origin O in the figure. As a result, the point of action Q1 moves downward and the point of action Q2 moves upward. The detection ring 200 is gently deformed from the positions of the fixed points P1 and P2 (positions fixed by the fixed members 510 and 520) toward the positions of the action points Q1 and Q2. When the moment-My around the negative Y-axis acts on the receiving body 100, the phenomenon opposite to that in FIG. 6 occurs. Further, when the moment + Mx around the positive axis of the X axis and the moment −Mx around the negative axis of the X axis act on the 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 structural portion when a moment around the Z axis acts on the receiving body 100 in a state where the support substrate 300 is fixed. FIG. 7 is a cross-sectional view on the XY plane showing a deformed state when a moment + Mz around the Z-axis is applied to the receiving body 100 of the basic structure shown in FIG. In this case as well, the support substrate 300 is immobile because it is fixed, but the receiving body 100 receives a moment + Mz in the positive direction of the Z axis and rotates counterclockwise around the origin O in the figure.

As a result, a counterclockwise force is applied to the action points Q1 and Q2 of the detection ring 200 in the figure. 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 shown in the figure. Become. Specifically, as shown in the figure, between points P2-Q1 and points P1-Q2, a tensile force acts on both ends of the quadrant arc of the detection ring 200, causing the quadrant arc to shrink inward and point P1-Q1. Between the gap and the points P2-Q2, a 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 the moment-Mz in the negative direction of the Z axis acts on the receiving body 100, the receiving body 100 rotates clockwise around the origin O in the figure, so that the deformation shown in FIG. 7 is turned inside out. The state occurs.

As described above, when the support substrate 300 of the basic structure shown in FIG. 1 is fixed and a force in each coordinate axis direction and a moment around each coordinate axis act on the receiving body 100, the deformation mode that occurs in the detection ring 200. However, these deformation modes are different from each other, and the amount of deformation is also different depending on the magnitude of the applied force and moment. Therefore, if the elastic deformation of the detection ring 200 is detected and information on its mode and size is collected, the force in each coordinate axis direction and the moment around each coordinate axis can be detected independently and independently. This is the basic principle of the detection operation in 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 structural portion described so far.

<<< §2. First-to-file force sensor detection principle >>>
The prior force sensor detects the direction and magnitude of the applied force and moment by measuring the displacement of the basic structural portion shown in FIG. 1. A fixed auxiliary body 350 is added for this displacement detection.

FIG. 8 is a top view (upper view) and a side view (lower view) showing an example in which a fixing auxiliary body 350 for displacement detection is added to the basic structural portion shown in FIG. 1. As shown in the figure, in this basic structure portion, the detection ring 200 is arranged inside the receiving body 100, and the fixing auxiliary body 350 is further arranged inside the detection ring 200. The fixing auxiliary body 350 is a columnar object centered on the Z axis, and its lower surface is fixed to the upper surface of the support substrate 300. The outer peripheral surface of the fixing 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 view) of the basic structural portion shown in FIG. 8 cut in the XY plane and a vertical cross-sectional view (lower view) cut in the VZ plane. 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, the negative region is located in the third quadrant of the XY plane, and 45 with respect to the X-axis. It is the axis that makes °. Further, the W axis passes through the origin O in the XYZ three-dimensional Cartesian coordinate system, the positive region is located in the second quadrant of the XY plane, the negative region is located in the fourth quadrant of the XY plane, and is orthogonal to the V axis. The axis. The cross-sectional view shown in the upper part of FIG. 9 is a view in which the V-axis positive direction is to the right and the W-axis positive direction is upward, and the fixing auxiliary body 350 is added to the basic structure shown in the upper part of FIG. , Corresponds to the figure rotated 45 ° clockwise. Further, since the lower vertical cross-sectional view of FIG. 9 is a vertical cross-sectional view cut along the VZ plane, the right direction is the positive direction of the V axis.

As described in §1, 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 on the detection ring 200. Here, four measurement points R1 to R4 (indicated by x) are further defined. As shown, the first measurement point R1 is in the V-axis positive region, the second measurement point R2 is in the W-axis positive region, the third measurement point R3 is in the V-axis negative region, and the fourth measurement point R4 is. They are arranged in the negative W-axis region, respectively. After all, in the upper cross-sectional view of FIG. 9, the basic ring road B (indicated by a thick alternate long and short dash 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, and R4 are arranged at equal intervals on the circular basic ring road B in this order. The four measurement points R1 to R4 are defined at such positions because the displacement caused by the elastic deformation of the detection ring 200 is most noticeable.

In order to detect the radial displacements of these four measurement points R1 to R4, the distances d1, d2, d3, and d4 indicated by the arrows in the upper cross-sectional view of FIG. 9 may be measured. These distances d1, d2, d3, and 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 facing reference surface facing the measurement target surface. When the distance is large, it means that the portion near the measurement point is bulging in the radial direction, and when the distance is small, the portion near the measurement point is the radius. It will show that it is shrinking in the direction. Therefore, if a capacitive element that electrically detects these distances is prepared, it is possible to measure the amount of deformation in the radial direction of the portion near each measurement point.

On the other hand, in order to detect the displacement of the four measurement points R1 to R4 in the vertical direction (Z-axis direction), the distances d5 and d7 shown by arrows in the lower vertical sectional view of FIG. 9 and the distances d6 and d8 not shown are shown. (The distance d6 is the distance directly below the measurement point R2 located at the back of the fixed auxiliary body 350, and the distance d8 is the distance directly below the measurement point R4 located at the 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, the measurement target surface located near each measurement point R1, R2, R3, R4, and the measurement target surface located on the upper surface of the support substrate 300. It is the distance to the facing reference plane facing the above. When the distance is large, it means that the portion near the measurement point is displaced upward, and when the distance is small, the portion near the measurement point is downward. It will indicate that it is displaced. Therefore, if a detection element that electrically detects these distances is prepared, it is possible to measure the amount of deformation in the vertical direction of the portion near each measurement point.

If the radial displacement and the vertical displacement of the four measurement points R1 to R4 can be measured in this way, the overall deformation mode and deformation amount of the detection ring 200 can be grasped, and the XYZ tertiary can be grasped. It becomes possible to detect the six-axis components of the force in each coordinate axis direction and the moment around each coordinate axis in the original Cartesian coordinate system. FIG. 10 is a top view showing a distance measurement point required 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 is measured for the second measurement point R2. (Deviation in the radial direction) and distance d6 (displacement in the vertical direction) are measured, and at the third measurement point R3, the distance d3 (displacement in the radial direction) and the distance d7 (displacement in the vertical direction) are measured. With respect to the fourth measurement point R4, the distance d4 (displacement in the radial direction) and the distance d8 (displacement in the vertical direction) are measured.

FIG. 11 shows changes in distances d1 to d8 when a force in each coordinate axis direction and a moment around each coordinate axis act on the receiving body 100 with the support substrate 300 fixed in the basic structure portion shown in FIG. It 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 fluctuate. It can be easily understood that such a result can be obtained by considering the specific modification of the detection ring 200 described in §1.

For example, when a force + Fx in the positive direction of the X axis acts on the receiving body 100, the detection ring 200 has a quadrant arc between points P1-Q1 and points P2-Q1 inward as shown in FIG. The contraction, the quadrant between points P1-Q2 and P2-Q2 deforms to bulge outward. Therefore, the distances d1 and d4 become smaller, and the distances d2 and d3 become larger. At this time, since the detection ring 200 is not deformed in the vertical direction, the distances d5 to d8 do not fluctuate. The + Fx row in the table of FIG. 11 shows such a result. For the same reason, when a force + Fy in the positive direction of the Y axis is applied, the result shown in the row of + Fy in the table of FIG. 11 is obtained.

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

Then, when a moment + My in the positive direction of the Y axis acts on the 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. Since it is displaced to, the distances d5 and d8 become smaller, and the distances d6 and d7 become larger. At this time, since the detection ring 200 is not deformed in the radial direction, the distances d1 to d4 do not fluctuate. The + My row in the table of FIG. 11 shows such a result. For the same reason, when the moment + Mx around the X-axis acts, the result shown in the row of + Mx in the table of FIG. 11 is obtained.

Finally, when a moment + Mz in the positive direction of the Z axis acts on the receiving body 100, the detection ring 200 is deformed as shown in FIG. 7, and the quarters between points P1-Q1 and P2-Q2. The arc bulges outward, and the quadrant between points P1-Q2 and P2-Q1 deforms inward. Therefore, the distances d1 and d3 become large, and the distances d2 and d4 become small. At this time, since the detection ring 200 is not deformed in the vertical direction, the distances d5 to d8 do not fluctuate. The + Mz row in the table of FIG. 11 shows such a result.

The table in FIG. 11 shows the results when a positive force and a positive moment are applied, but when a negative force and a negative moment are applied, "+" and "-" are shown. The result of reversing "" will be obtained. After all, the change pattern of the distances d1 to d8 is different in each case where the 6-axis component acts, and the larger the applied force or moment, the larger the amount of change in the distance. Therefore, if a predetermined calculation is performed based on the measured values of the distances d1 to d8 by the detection circuit, the detected values of the 6-axis components can be output independently.

The prior force sensor is a basic structure shown in FIG. 8 to which a capacitance element and a detection circuit are further added, and electrically detects a change in the capacitance value of the capacitance element arranged in each part. This measures the displacement of a specific location and detects the direction and magnitude of the applied force and moment.

FIG. 12 shows a cross-sectional view (upper view) of the force sensor configured by adding a capacitance element to the basic structure shown in FIG. 9 cut in the XY plane and a vertical cross-sectional view (lower view) cut in the VZ plane. Figure). Comparing the basic structure shown in FIG. 9 with the force sensor shown in FIG. 12, it can be seen that 16 electrodes E11 to E18 and E21 to E28 are added in the latter. The eight sets of capacitive elements composed of these 16 electrodes function as detection elements for measuring the eight distances d1 to d8 described above.

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

On the other hand, eight fixed electrodes E11 to E18 are provided at positions facing these eight displacement electrodes E21 to E28 (opposing reference planes). These eight fixed electrodes E11 to E18 are literally electrodes that are directly or indirectly fixed to the support substrate 300, and always maintain a fixed position regardless of the deformation of the detection ring 200. Specifically, fixed electrodes E11 to E14 are provided on the outer peripheral surface of the columnar fixed auxiliary body 350 at positions facing the displacement electrodes E21 to E24, and these electrodes are connected via the fixed auxiliary body 350. It is indirectly fixed on the support substrate 300. Further, the 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 at the back of the fixed auxiliary body 350, and the displacement electrode E18 is located at the 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 thin-film deposition layer or a plating layer, the thickness thereof is about several μm, and the thickness of each electrode E11 to E28 shown in FIG. 12 on the drawing is correct in terms of actual size ratio. It is 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 surfaces located in the vicinity of the respective measurement points R1 to R4 on the inner peripheral surface and the lower surface of the detection ring 200, and fixing assistance. Eight sets of capacitive elements are formed by eight sets of fixed electrodes E11 to E18 provided on the facing reference surfaces defined at positions facing each measurement target surface on the outer peripheral surface of the body 350 and the upper surface of the support substrate 300. It will be configured. Then, the prior force sensor measures the displacement of each measurement point R1 to R4 by electrically detecting the capacitance value of these eight sets of capacitive elements, and based on the table shown in FIG. 11, The direction and magnitude of the force and moment acting on the receiving body 100 will be detected.

As described above, the prior application force sensor can be configured by using a simple basic structure as shown in FIG. 12, but since it is necessary to arrange the capacitive elements at various places, the capacitive elements are used. The configuration of the constituent electrodes has to be complicated. Specifically, in order to add a capacitive element to the basic structure, a step of forming an electrode layer parallel to the substrate surface (XY plane) such as fixed electrodes E15 to E18 and displacement electrodes E25 to E28. It is necessary to perform a step of forming an electrode layer perpendicular to the substrate surface (XY plane), such as 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 a semiconductor manufacturing process or the like can be used, but the latter process requires a complicated method to be adopted and mass production is performed. Problems are likely to occur above.

Moreover, the relative positions of the pair of electrodes constituting the individual capacitive elements are important factors that affect 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 made parallel to each of the capacitive elements. , It is necessary to adjust the electrode spacing for a plurality of capacitive elements so that they are equal to each other. For this reason, the first-to-file force sensor has a problem that the production efficiency is lowered and the cost is soared when it is used commercially.

In order to solve such a problem in the prior force sensor, the present invention improves the degree of freedom in design and improves the production efficiency by adopting a structure in which a detection unit that causes elastic deformation is provided at a specific position of the detection ring. It proposes a new device that can enhance the. Hereinafter, the present invention will be described in detail based on specific embodiments.

<<< §3. Basic Embodiment of the present invention >>>
<3-1. Detection ring structure>
FIG. 13 is a perspective view (FIG. (A)), a side view (FIG. (B)), and a bottom view (bottom view) of the 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 has a simple annular structure, whereas the detection ring 600 used in the force sensor of the present application shown in FIG. 13 has this simple structure. Detection units D1 to D4 formed by combining elastically deformable plate-shaped pieces are provided at four locations in 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 a partial material removal process, and the portion subjected to the material removal process. As a result, detection units D1 to D4 as shown in the figure are formed. The detection ring 200 shown in FIG. 1 is 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 ring 600 shown in FIG. 13 is obtained by further 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, it may be produced by casting using a mold, resin molding, press processing, or the like.

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 viewed from diagonally below. As shown in the figure, the detection ring 600 has four sets of detection units D1 to D4 and four sets of connecting parts L1 to L4 for connecting the detection units D1 to D4 to each other. That is, the detection ring 600 has a structure in which the connecting portions L1 to L4 are interposed between the detection units D1 to D4, respectively.

As shown in the detection unit D4 of the side view of FIG. 13 (b) (only the outer peripheral surface portion is shown to avoid cluttering the figure), the detection unit D4 in this embodiment is the first. It is composed of three plate-shaped pieces (leaf springs), which are a deformed portion 61, a second deformed portion 62, and a displacement portion 63. The other detection units D1 to D3 also have a similar structure. As described above, since each of the detection units D1 to D4 is composed of a plate-shaped piece having a thickness thinner than that of the connection portions L1 to L4, the detection portions D1 to D4 are more likely to be elastically deformed than the connection portions L1 to L4. have. Therefore, as will be described later, when an external force acts on the detection ring 600, the elastic deformation of the detection ring 600 based on the external force is concentrated on the detection units D1 to D4, and the elastic deformation of the connecting portions L1 to L4 is caused. In practice, it can be ignored.

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 is used. In the detection ring 600 used for the above, the deformation is concentrated on the detection units D1 to D4 where elastic deformation is likely to occur. Therefore, it becomes possible to generate more efficient deformation, and more efficient detection becomes possible. Specifically, by not only increasing the detection sensitivity but also devising the shape and structure of the detection unit, it becomes possible to freely set the mode of elastic deformation. The specific modes 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) looking up from below. When the X axis is taken to the right, the Y axis is an axis facing downward. As shown in the figure, clockwise from the connecting portion L1 arranged on the X-axis, the connecting portion L1, the detecting portion D1, the connecting portion L2, the detecting portion D2, the connecting portion L3, the detecting portion D3, and the connecting portion L4. The detection units D4 are arranged in this order. As will be described later, the fixed points P1 and P2 (indicated by black circles) on the Y-axis are fixed to the support substrate, and the external forces applied from the receiving body are applied to the points of action Q1 and Q2 (indicated by white circles) on the X-axis. Works. As a result, each of the detection units D1 to D4 is elastically deformed 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-like hatching is for showing the regions of the detection units D1 to D4, and does not show the cross section). Since it is a top view, contrary to FIG. 13C, L1, D1, L2, D2, L3, D3, L4, and D4 are arranged counterclockwise on the detection ring 600 in this order. As shown in the figure, on the XY plane, the V-axis is defined as a coordinate axis in which the X-axis is rotated 45 ° counterclockwise around the origin O, and the Y-axis is rotated 45 ° counterclockwise around the origin O. The W axis is defined as the coordinate axis. <I>, <II>, <III>, and <IV> in the figure indicate the first to fourth quadrants in the XY two-dimensional coordinate system. The four sets of detection units D1, D2, D3, and 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 ring road B shown by the thick alternate long and short dash 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 ring road 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 case of the illustrated embodiment, the basic ring road 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 600, and is a ring-thick portion (connecting portion L1) of the detection ring 600. It becomes the center line of ~ L4).

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 of the positive W axis and the basic ring road B. Defined at the position, the third detection point R3 is defined at the intersection position of the negative V axis and the basic loop path B, and the fourth detection point R4 is the intersection of the negative W axis and the basic loop path 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 in FIG. 14 as a mesh-like hatching region, the first detection unit D1 is arranged at the position of the first detection point R1, and the second detection unit D2 is located at the position of the second detection point R2. The third detection unit D3 is arranged at the position of the third detection point R3, and the fourth detection unit D4 is arranged at the position of the fourth detection point R4.

On the other hand, the points P1 and P2 indicated by black circles in FIG. 15 are fixed points, and the 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 points of action Q1 and Q2 are points on which the force from the receiving body 100 acts. In the case of the illustrated example, the fixed points P1 and P2 are defined at the intersection position between the Y axis and the basic ring road B, and the action points Q1 and Q2 are defined at the intersection position between the X axis and the basic ring road B. There is. Therefore, in the force sensor using the detection ring 600, the force or moment acting on the two points Q1 and Q2 on the X axis in the state where the two points P1 and P2 on the Y axis are fixed is applied to 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 points of action Q1 and Q2 are alternately arranged along the basic ring road B. Such an alternating arrangement is important in causing effective deformation of the detection ring 600 when an external force to be detected acts on it, as will be described later. Further, four sets of detection points R1 to R4 are arranged between adjacent fixed points and action points. Such an arrangement is also important in causing effective displacement of the detection units D1 to D4 when an external force to be detected acts.

<3-2. Structure of basic embodiment>
Subsequently, 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 portion of the force sensor according to the embodiment and a side cross-sectional view (lower view) obtained by cutting the basic structure portion in the XZ plane. As shown in the figure, this basic structural part includes a 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 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 receiving body 100, as shown in the lower side sectional view. The inner peripheral surface of the 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 are connected. It is connected to the upper surface of the 300 by fixing members 510 and 520 arranged at positions along the Y axis.

Comparing the basic structural part of the prior invention shown in FIG. 2 with the basic structural part 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 only the point that is done. Although there are slight differences in dimensions and shapes for each of the other components, there is no difference in essential functions. Therefore, in FIG. 16, the corresponding components are designated by the same reference numerals 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. Therefore, when an external force (force or moment) acts on the detection ring 600, the deformation is concentrated exclusively on the detection units D1 to D4 as described above.

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

As shown in FIG. 17A, connecting portions L are located on both the left and right sides of the detection portion D. This connecting portion L corresponds to any of four sets of connecting portions L1 to L4. For example, when the detection unit D shown in FIG. 17A is the fourth detection unit D4 shown in FIG. 13, the connection unit L arranged on the right side thereof is the connection unit L1 shown in FIG. Corresponds to, 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 causes elastic deformation due to the action of an external force to be detected, a second deformation unit 62 that causes elastic deformation due to the action of an external force to be detected, and a second. It has a deformed portion 61 of 1 and a displacement portion 63 that is displaced by elastic deformation of the second deformed portion 62, and is connected to the end of the connecting portion L arranged on the left side and the connecting portion L arranged on the right side. It is arranged between the end of the portion L.

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

In the case of the example shown here, the displacement portion 63 is also a thin plate-shaped member and therefore has flexibility, but the displacement portion 63 does not necessarily have to be a flexible member. No (of course, it may be flexible). The role of the displacement portion 63 is to generate a displacement when an external force is applied, and in order to generate such a displacement, the first deformed portion 61 and the second deformed portion 62 have flexibility. It's enough if you have it. Therefore, the displacement portion 63 does not necessarily have to be formed of a plate-shaped member having a thin wall thickness, and may be a thicker wall member. On the other hand, the connecting portion L may have a certain degree of flexibility, but the external force acting may cause effective deformation of the first deformed portion 61 and the second deformed portion 62. , It is preferable that the connecting portion L is not deformed as much as possible.

The outer end of the first deformed portion 61 is connected to the connecting portion L adjacent thereto, and the inner end of the first deformed portion 61 is connected to the displacement portion 63. Further, the outer end of the second deformed portion 62 is connected to the connecting portion L adjacent thereto, and the inner end of the second deformed portion 62 is connected to the displacement portion 63. In the case of the example shown in FIG. 17 (a), the first deformed portion, the second deformed portion, and the displaced portion are the first plate-shaped piece 61, the second plate-shaped piece 62, and the third plate-shaped piece, respectively. It is composed of 63, and the outer end (left end) of the first plate-shaped piece 61 is connected to the right end portion 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. ) Is connected to the left end of the third plate-shaped piece 63, and the outer end (right end) of the second plate-shaped piece 62 is connected to the left end of the connecting portion L arranged on the right side. 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 set at the position of the detection point R and orthogonal to the basic plane (XY plane) including the basic ring road B, and the detection unit D is the normal line N. Is arranged so that is in the center. Further, 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 first plate-shaped piece 61 The inclination direction (downward to the right) and the inclination direction (upward to the right) of the second plate-shaped piece 62 are opposite. In particular, in the case of the illustrated example, the cross-sectional shape of the detection unit D is line-symmetrical with respect to the normal line N, and both the upper and lower surfaces of the third plate-shaped piece 63 form a plane parallel to the XY plane.

As described above, with respect to the cross section including the basic annular road 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 N are opposite to each other. The displacement direction of the third plate-shaped piece 63 (displacement portion) is opposite between the case where the compressive force f1 acts in the direction along the path B and the case where 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 the compressive force f1 (white arrow in the figure) acts on the detection unit D in the direction along the basic ring road B, the width of the detection unit D is reduced. Since the 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 vertically standing state. As a result, the third plate-shaped piece 63 (displacement portion) is displaced downward as shown by the black arrow in the figure. On the other hand, as shown in FIG. 17 (c), when an extension force f2 (white arrow in the figure) acts on the detection unit D in the direction along the basic ring road B, the width of the detection unit D is widened. Since the 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 shown by the black arrow in the figure.

The deformation mode when the compressive force f1 or the extension force f2 acts on the detection unit D in the direction along the basic ring road B has been described above, but of course, when the external force acts in any other direction, , A deformation mode different from that shown in FIG. 17 will occur. For example, in FIG. 17 (a), a force for moving the right side connecting portion L is applied to the upper side of the figure, and at the same time, a force for moving the left side connecting portion L is applied to the lower side of the drawing. Then, a deformation that becomes asymmetric with respect to the normal N occurs. However, as will be described later, in the force sensor according to the basic embodiment shown here, it is sufficient to substantially grasp the operating principle by considering only the deformation mode 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 displacements of the displacement portions 63 generated in the four sets of detection portions D1 to D4, but the displacement of the displacement portions 63 is detected. A capacitive element is used as a detection element for detecting. In other words, the force sensor according to the basic embodiment of the present invention is configured by adding a capacitive element and a detection circuit to the basic structural portion shown in FIG.

FIG. 18 is a partial cross-sectional view showing a detailed structure in which electrodes are provided in predetermined portions of the detection portions D1 to D4 of the detection ring 600 shown in FIG. 13 and the support substrate 300 facing the detection portions D1 to D4. Also in FIG. 18, the detection unit D represents four sets of detection units D1 to D4, and shows a cross-sectional portion when the detection ring 600 is cut by a cylindrical surface including the basic ring road B. .. That is, the part of the detection ring 600 shown in the upper part of FIG. 18 corresponds to the part of the detection ring 600 shown in FIG. 13 (a).

As described above, both sides of the third plate-shaped piece 63 form a plane parallel to the XY plane including the basic ring road B in a state where no external force (force or moment) is applied. On the other hand, the support substrate 300 is arranged so that both the upper and lower surfaces thereof are parallel to the XY plane. Therefore, as shown in the drawing, the third plate-shaped piece 63 (displacement portion) and the facing surface of the support substrate 300 are in a parallel state. Moreover, in the case of the embodiment shown here, since the cross-sectional shape of the detection unit D is line-symmetrical with respect to the normal line N, the compressive force f1 or the extension force f2 as shown in FIGS. When acted, the third plate-shaped piece 63 (displacement portion) is displaced in the form of moving in parallel in the vertical direction in the figure, and the third plate-shaped piece 63 (displacement portion) and the facing surface of the support substrate 300. Is always kept parallel. Of course, when the third plate-shaped piece 63 is deformed by an external force (f1, f2), the parallel state is not maintained, but the distance between the electrodes E1 and E2, which will be described later, is still the external force (f1, f2). If it changes based on, there is no problem in the detection operation.

In order to detect the displacement of the displacement portion, as shown in the drawing, the fixed electrode E1 is fixed to the upper surface of the support substrate 300 via the insulating layer I1, and to the lower surface of the third plate-shaped piece 63 (displacement portion). The displacement electrode E2 is fixed via the insulating layer I2. If the support substrate 300 is maintained in the fixed state, the position of the fixed electrode E1 is fixed, but the position of the displacement electrode E2 is displaced according to 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 the capacitive element C is formed by both of them. 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 constituting the capacitive element C fluctuates. Therefore, the displacement direction (upper or lower in the figure) and the amount of displacement of the third plate-shaped piece 63 (displacement portion) can be detected based on the capacitance value of the capacitance element C.

Specifically, as shown in FIG. 17 (b), when the compressive force f1 acts on the detection unit D, the distance between the two electrodes is shortened, the capacitance value of the capacitance element C is increased, and FIG. As shown in the above, when the extension force f2 acts on the detection unit D, the distance between the two electrodes increases, and the capacitance value of the capacitance 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 reality, the fixed electrodes E1 and the displacement electrodes are actually formed for the four sets of detection units D1 to D4 shown in FIG. 13, respectively. E2 is provided, and four sets of capacitive elements C1 to C4 are formed. A specific method for detecting each acting external force component using these four sets of capacitive elements C1 to C4 will be described in §3-4 below.

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, which makes the detection ring 600 conductive such as metal. This is because it is composed of materials. Similarly, the fixed electrode E1 is fixed to the support substrate 300 via the insulating layer I1 because the support substrate 300 is made of a conductive material such as metal. That is, in the case of the basic structural portion shown in FIG. 16, since the 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 placed on the surface of the displacement portion 63. 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, it is not necessary to provide the insulating layer I1.

Further, 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, and therefore 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 individually provided in four sets. It is only the region facing the fixed electrode E1 of. Therefore, the four sets of capacitive elements C1 to C4 behave as separate capacitive elements, and there is no problem in principle.

On the contrary, when the support substrate 300 is made of a conductive material such as metal, a part of the upper surface of the support substrate 300 can be used as the fixed electrode E1. For example, in the embodiment shown in FIG. 18, if the support substrate 300 is made of a conductive material, a part of the upper surface thereof functions 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 has 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 individually provided in four sets. Only the region facing the displacement electrode E2 of. Therefore, the four sets of capacitive elements C1 to C4 behave as separate capacitive elements, 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 the support substrate 300 is made of a conductive material such as metal, the individual displacement electrodes E2 and the individual fixed electrodes E1 can be formed. Since the step of providing can be omitted, the production efficiency can be further improved.

However, if such an abbreviated structure is adopted, the entire detection ring 600 or the entire support substrate 300 becomes a common electrode, and stray capacitances are formed in various unintended parts. Therefore, a noise component is likely to be mixed in the detected value of the capacitance, and the detection accuracy may be lowered. 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 as in the embodiment shown in FIG. It is preferable to provide the individual displacement electrode E2 and the individual fixed electrode E1 via the layer.

The ease 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 highly sensitive sensor that can detect even a minute external force, but the maximum value of the detectable external force is suppressed. On the contrary, if the detection unit D which is hard to be elastically deformed is used, the maximum value of the detectable external force can be increased, but the sensitivity is lowered, so that the minute external force cannot be detected.

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

As described above, in the drawings of the present application, the actual size of each part is ignored for convenience of illustration. For example, in FIG. 18, the thickness of the fixed electrode E1 and the displacement electrode E2 and the thickness of the insulating layer I1 and the insulating layer I2 are drawn so as to be substantially the same as the thickness of each of the plate-shaped pieces 61, 62, 63. However, each of these electrodes and the insulating layer 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 preferable.

On the other hand, the receiving body 100 and the supporting substrate 300 shown in FIG. 16 do not need to be members that cause elastic deformation in principle of detecting an external force. Rather, it is preferable that the receiving body 100 and the supporting substrate 300 are completely rigid bodies so that the applied external force contributes 100% to the deformation of the detection ring 600. In the illustrated example, the reason why the annular structure is used as the receiving body 100 is not to facilitate elastic deformation, but to form a thin force sensor as a whole by arranging it outside the detection ring 600. Because.

That is, in the case of the basic embodiment shown in FIG. 16, the receiving body 100, the detection ring 600, and the support substrate 300 can all be formed of a flat structure having a small thickness in the Z-axis direction, and the receiving body. Since the structure in which the 100 is arranged outside the detection ring 600 is adopted, the axial length (length in the Z-axis direction) of the entire sensor can be set short. Further, in the case of the basic embodiment shown in FIG. 16, it is sufficient to arrange 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), and thus the production efficiency. Can be expected to have the effect of improving.

This effect can be easily understood by comparing with the configuration of the capacitive element of the prior force sensor illustrated in FIG. In the prior force sensor illustrated in FIG. 12, 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 fixing auxiliary body 350 are used. 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. Will be done.

In this way, in order to form both the electrode along the horizontal plane and the electrode along the vertical plane, a rather time-consuming process is required, and a great work load is required for the position adjustment. As a result, production efficiency is inevitably reduced. For example, even if the central axis of the fixing auxiliary body 350 is slightly deviated from the Z axis, the positions of the fixed electrodes E11 to E14 fluctuate, and the capacitance value of the capacitive element fluctuates. 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 force sensor, it is necessary to align the central axis with high accuracy when attaching the fixing auxiliary body 350 and the detection ring 200.

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 sets of detection portions D1 to D4, respectively, and are mounted on the support substrate 300. Fixed electrodes E1 may be formed at opposite positions. Each of the electrodes becomes an electrode along a horizontal plane, and accurate thickness control is possible by using a general film forming process. Moreover, each electrode is not required to have strict accuracy regarding 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 fixing members 510 and 520, the positional accuracy of each electrode in the vertical direction can be easily ensured. can. Therefore, even in the case of commercial mass production, it is possible to make the counter electrodes parallel to each capacitive element and to make adjustments so that the electrode spacings of the plurality of capacitive elements are 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 area occupied by the projected image on the XY plane) is compared with the size of the displacement electrode E2 (planar size, that is, the area occupied by the projected image on the XY plane). , Occupied 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 figure or in the direction perpendicular to the paper surface of the figure (direction along the XY plane), the area of the displacement electrode E2 facing the fixed electrode E1 does not change. It is a consideration to do. In other words, regardless of the three-dimensional direction in which the displacement electrode E2 is displaced, the effective area of the capacitive element C is always maintained constant as long as the positional relationship between the two electrodes is maintained in parallel.

FIG. 19 is a diagram showing a principle that the effective area of the capacitive element C is kept constant even when the relative position of the displacement electrode E2 with respect to the fixed electrode E1 changes. Now, consider a case where a pair of electrodes EL and ES are arranged so as to face each other as shown in FIG. 19 (a). Both electrodes EL and ES are arranged so as to be parallel to each other at predetermined intervals, and constitute a capacitive element. However, the area of the electrode EL is larger than that of the electrode ES, and when the contour of the electrode ES is projected onto the surface of the electrode EL to form a normal 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. 19B is a side view of the pair of electrodes ES and EL shown in FIG. 19A. The hatched region in the figure is a portion that functions as a substantial capacitive element, and the effective area as a capacitive element is the area of the hatched electrode (that is, the area of the electrode ES). Become.

Now, consider the vertical plane U as shown by the alternate long and short dash line in the figure. Both the electrodes ES and EL are arranged so as to be parallel to the vertical plane U. Here, assuming that the electrode ES is moved vertically upward along the vertical plane U, the facing portion on the electrode EL side moves upward, but the area of the facing portion does not change. Even if the electrode ES is moved downward or toward the back or front 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 a normal projection image, the projected image of the electrode ES is completely inside the surface of the electrode EL. As long as the contained state is maintained, the effective area of the capacitive element composed of both electrodes becomes 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 similar to the relationship between the electrode ES and the electrode EL shown in FIG. 19, which of the displacement electrodes E2 is affected by the action of an external force. Even if the displacement is made in the direction, the effective facing area of the pair of electrodes constituting the capacitive element C is constant as long as the parallel electrode E2 and the fixed electrode E1 are kept parallel to each other. This means that the change in the capacitance value of the capacitance 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 capacitance element C depends only on the displacement of the displacement portion 63 in the direction along the normal line N, and occurs in the direction orthogonal to the normal line N. It means that it does not depend on displacement. This is useful in accurately detecting the applied external force based on the above-mentioned principle.

As described above, in the embodiment in which the capacitance element is used as the detection element, the capacitance element C is moved even when the displacement electrode E2 is translated with respect to the fixed electrode E1 as a result of a predetermined external force acting on the detection ring 600. 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 areas of the pair of constituent electrodes do 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. Yes, for example, a circular electrode may be used.

<3-4. Specific detection method for individual external force components>
Subsequently, with respect to the force sensor using the basic structure shown in FIG. 16, with the support substrate 300 fixed, the forces Fx, Fy, Fz in each coordinate axis direction and the moments Mx around each coordinate axis are attached to the receiving body 100. 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 unit D (the lower surface of the displacement unit 63), and the fixed electrode E1 is arranged on the opposite portion of the upper surface of the support substrate 300. Then, the capacitance element C is formed by the pair of electrodes E1 and E2. Therefore, here, the capacitance elements formed for the four sets of detection units D1 to D4 are referred to as capacitance elements C1 to C4, respectively, and the capacitance values of the capacitance elements C1 to C4 are set to the same reference numerals C1 to C1. It will be shown by C4.

The amount of change (degree of increase / decrease) in the capacitance value of each of the capacitance elements C1 to C4 when an external force Fx, Fy, Fz, Mx, My, Mz is applied to the receiving body 100 is shown in the table of FIG. Will be. In this table, "+" indicates that the capacitance value increases (the electrode spacing of the capacitance element C decreases), and "-" indicates that the capacitance value decreases (the electrode spacing of the capacitance element C increases). ) Indicates that. In addition, "++" indicates that the degree of increase in the capacitance value is larger than that of "+", and "(+)" indicates that the degree of increase in the 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 in capacitance value is smaller than that of "-". Show 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, in particular, the size and thickness of the plate-shaped pieces 61, 62, 63 constituting the detection part D. The difference between "(+)", "+", and "++" in the table shown in the present application and the difference between "(-)", "-", and "---" are only relative. It is a thing. In particular, the forces Fx, Fy, Fz (unit: N) and the moments Mx, My, Mz (unit: Nm) are different physical quantities and cannot be directly compared.

The table of FIG. 20 shows the measured values when a force of the same magnitude is applied to the outer peripheral portion of the receiving body 100 in each direction (direction in which the force acts as an external force of Fx, Fy, Fz, Mx, My, 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 receiving body 100 by the radius of the outer peripheral portion of the receiving body 100. Based on such conversion values, the table of FIG. 20 is indicated by "(+)" and "(-)" when the absolute value is less than 5, and "(-)" when the absolute value is 5 or more and less than 50. It is indicated by "+" and "-", and when the absolute value is 50 or more, it is indicated by "++" and "---".

To obtain the results shown in the table of FIG. 20, the detection of the detection ring 600 shown in FIG. 16 can be obtained by referring to the deformation mode of the detection ring 200 in the prior application force sensor shown in FIGS. 4 to 7. 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. Although the detection ring 200 and the detection ring 600 are different in the structural parts of the detection units D1 to D4, they are both annular rings, and when the fixed points P1 and P2 on the Y axis are fixed, they are on the X axis. It is common that the points of action Q1 and Q2 are deformed by the action of an external force. Therefore, the stress applied to the positions of the detection units D1 to D4 of the detection ring 600 is the same as the stress applied to the corresponding positions of the detection rings 200 shown in FIGS. 4 to 7.

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

Similarly, when a force + Fy in the positive direction of the Y axis acts on the receiving body 100, a compressive force f1 acts between points P1-Q1 and P1-Q2, and between points P2-Q1 and P2-. A stretching force f2 acts between Q2. Therefore, in the case of the detection ring 600 shown in FIG. 16, the compressive force f1 acts on the detection units D1 and D2, and the 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.

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

On the other hand, when a moment + My in the positive direction of the Y axis acts on the 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. Displace 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 figure are displaced upward. Therefore, the electrode spacing of the capacitance elements C1 and C4 becomes small, and the capacitance values C1 and C4 increase. Further, the electrode spacing of the capacitance elements C2 and C3 becomes large, and the 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 around the X-axis forward acts on the receiving body 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, and the figure shows. The detection units D1 and D2 located in the upper half are displaced upward. Therefore, the electrode spacing of the capacitance elements C3 and C4 becomes small, and the capacitance values C3 and C4 increase. Further, the electrode spacing of the capacitance elements C1 and C2 becomes large, and the capacitance values C1 and C2 decrease. Each column of the Mx row in the table of FIG. 20 shows such a result.

Even when the moments + Mx and + My act, the detection units D1 to D4 are slightly inclined with respect to the XY plane, so that the pair of electrodes forming the respective capacitive elements C1 to C4 are not parallel. Therefore, the effective facing areas of the pair of electrodes fluctuate slightly, but the capacitance values C1 to C4 are mainly affected by the fluctuation of the distance between the electrodes.

Finally, when a moment + Mz around the Z-axis positively acts on the receiving body 100, the detection ring 200 is deformed as shown in FIG. 7, and a compressive force is applied between points P1-Q1 and P2-Q2. f1 acts, and an extension force f2 acts between points P1-Q2 and points P2-Q1. Therefore, in the case of the detection ring 600 shown in FIG. 16, the compressive force f1 acts on the detection units D1 and D3, and the 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 Mz row in the table of FIG. 20 shows such a result.

In the table of FIG. 20, each column of the Fx row and the Fy row is "(+)" or "(-)" when Fx and Fy acted and Fz and Mz acted. This is because the amount of displacement generated in the displacement units 63 of the detection units D1 to D4 is smaller than that of the displacement units 63. On the other hand, the reason why each column of the Mx line and the My line is "++" or "---" is that when Mx and My act, the detection ring is greatly tilted as shown in FIG. This is because the displacement electrode E2 is largely displaced.

The table in FIG. 20 shows the results when a positive force and a positive moment are applied, but when a negative force and a negative moment are applied, "+" and "-" are shown. The result of reversing "" will be obtained.

The force sensor according to the basic embodiment (first embodiment) of the present invention has four sets of capacitive elements C1 to C4 (four sets of displacement electrodes and four sets of fixed electrodes) in the basic structural portion shown in FIG. ) And a detection circuit are added. This force sensor measures the displacement of 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 measures the displacement of the applied force and moment. It has a function to detect the orientation and size. Here, the principle of detecting the force and the moment with respect to each coordinate axis by this force sensor and an example of a specific detection circuit will be shown.

As described above, in this force sensor, when an external force Fx, Fy, Fz, Mx, My, Mz is applied to the receiving body 100, the capacitance values of the capacitive elements C1 to C4 are shown in the table of FIG. It causes fluctuations as shown in. Here, since the amount of fluctuation of "(+)" and "(-)" is smaller than that of "+" and "-", it will be treated as approximately 0. Then, the table of FIG. 20 is approximately replaced with the table of FIG. 21. Assuming the table of FIG. 21, the four-axis components Fz, Mx, My, and Mz of the external force acting on the 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 operation of Fz =-(C1 + C2 + C3 + C4) by referring to each column of the Fz row in the table of FIG. Moreover, if this arithmetic expression is used, it can be seen that even if other axis components other than Fz are present, they cancel each other out. For example, when the results of each column of the Mx, My, and Mz rows are substituted into the above calculation formulas and calculated, the results of Fz = 0 are obtained in each case. Therefore, the value Fz obtained by the above calculation formula is a value indicating only the force component Fz in the Z-axis direction that does not include other axis components. This is because the structures of the detection units D1 to D4 and the capacitance elements C1 to C4 have symmetry with respect to both the XZ plane and the YZ plane.

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

After all, by using the four arithmetic expressions shown in FIG. 22, it is possible to detect the values of the four-axis components Fz, Mx, My, and Mz without the interference of the other-axis components. Of course, since the table of FIG. 21 was obtained by performing an approximation with the columns of "(+)" and "(-)" in the table of FIG. 20 set to 0, in reality, some other axis components are present. It is mixed as a detection error. However, if it is a force sensor used in an application in which the error is within an allowable range, there is no problem in practical use.

FIG. 23 is a circuit diagram showing an example of a detection circuit that outputs an electric signal showing the four-axis components of the force Fz and the moments Mx, My, and Mz based on the arithmetic expression shown in FIG. The capacitance elements C1 to C4 shown in this circuit diagram are capacitance elements C1 to C4 provided in the detection units D1 to D4. Each of the capacitance 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 all indicated by the same reference numerals E1, and the displacement electrodes are indicated by individual reference numerals E2 (D1), E2 (D2), E2 (D3), and E2 (D4). It is shown by. On the contrary, four sets of displacement electrodes E2 may be connected to each other, and four sets of fixed electrodes E1 may be electrically independent electrodes.

The C / V conversion circuits 11 to 14 are circuits that convert the capacitance values C1 to C4 of the capacitance elements C1 to C4 into voltage values V1 to V4, respectively, and the converted voltage values V1 to V4 are respective. It becomes a value corresponding to the capacitance values C1 to C4. The addition / subtraction calculators 15 to 18 each have 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, the arithmetic may be performed using a microprocessor instead of the addition / subtraction arithmetic units 15 to 18.

After all, if the capacitance 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 portion shown in FIG. 16, and the detection circuit shown in FIG. 23 is further prepared, 4 It is possible to realize a force sensor capable of detecting the values of the shaft components Fz, Mx, My, and Mz. Here, the four sets of capacitive elements (detection elements) are the displacement electrode E2 formed on the lower surface of the detection ring 600 (the lower surface of the displacement portion 63) and the fixed electrode E1 formed on the upper surface of the support substrate 300. , Simplifies the manufacturing process.

Further, the distance between the electrodes of the pair of electrodes (fixed electrode E1 and displacement electrode E2) constituting each of the capacitance elements C1 to C4 is defined by the height dimension of the fixing members 510 and 520 shown in FIG. 16, which is sufficient. Accuracy can be easily ensured. Therefore, complicated work for adjusting the electrode spacing becomes unnecessary, and high production efficiency can be ensured even in the case of commercial mass production.

Of course, this force sensor cannot detect Fx and Fy, and as described above, the detection is performed based on the approximation table shown in FIG. 21, so that other axis components are slightly mixed. Become. However, it is sufficient if the four-axis components Fz, Mx, My, Mz or a part of them can be detected, and if the error based on the above approximation is within the permissible range, this force sensor can be fully utilized industrially. It is possible. As another embodiment, a force sensor capable of detecting all of the 6-axis components Fx, Fy, Fz, Mx, My, and Mz and a force sensor capable of obtaining a more accurate detection value § It will be described in 5 and later.

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

The force sensor according to the present invention includes a receiving body that is affected by a force or moment to be detected, a detection ring having a structure that causes at least a part of elastic deformation, and a support that supports the detection ring. It has a function of detecting a force or a moment acting on one of the 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 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, other members are arranged above the support substrate 300, the receiving body 100 is an annular member, and the other members are arranged outside the detection ring 600, the whole is taken. Since a thin sensor can be realized, it is preferable to use the support substrate 300 as a support and the 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 road B. A detection point R is defined on this 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 units D1 to D4 located at the respective detection points R1 to R4, and connecting parts L1 to L4 located on both sides of the individual detection units. ..

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

The detection units D1 to D4 have a structure in which at least a part of the detection units D1 to D4 elastically deform based on the applied force when a force is applied between the action points Q1 and Q2 and the fixed points P1 and P2. Since the detection unit D illustrated in FIG. 17 is composed of three plate-shaped pieces 61, 62, 63, the whole becomes a member that causes elastic deformation. For example, the displacement portion 63 is increased in thickness. , A member that does not cause elastic deformation may be used.

The force sensor according to the present invention further includes a detection element that detects elastic deformation generated in the detection units D1 to D4, and a receiver 100 and a support (support substrate 300) based on the detection results of the detection elements. It is equipped with a detection circuit that outputs an electric signal indicating the force or moment acting on one side when a load is applied to the other side.

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 unit D and the position facing the displacement electrode E2 of the support (support substrate 300) The detection element is composed of a capacitance element C having a fixed fixed electrode E1 and a fixed electrode E1. Here, the displacement electrode E2 is located at a position where displacement is generated with respect to the fixed electrode E1 based on the elastic deformation generated in the detection unit D (specifically, in the case of the example shown in FIG. 18, the lower surface of the displacement unit 63). Have been placed. Then, as illustrated in FIG. 23, the detection circuit outputs an electric signal indicating the acting force or moment based on the fluctuation of the capacitance value of each of the capacitance elements C1 to C4.

In the basic embodiment described in §3, for convenience, it has been described that the force or moment acting on the receiving body 100 is detected in a state where the supporting substrate 300 (supporting body) is fixed, but conversely. Even if the force or moment acting on the support substrate 300 (support) is detected in a state where the receiving body 100 is fixed, the operating principle 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 receiving body 100, and only the detection operation for detecting the force or moment applied to the receiving body while the support is fixed will be described. , Even if the support and the receiving body are replaced, there is no difference in the detection principle. Therefore, for example, in the basic structure shown in FIG. 16, even if the annular member 100 is interpreted as a support and the substrate-shaped member 300 is interpreted as a receiving body, there is no difference in the operating principle of the force sensor. (In this case, points P1 and P2 are points of action, and points Q1 and Q2 are fixed points).

In the example shown in FIG. 16, the detection ring 600 extends along the basic ring road B located in the XY plane with the Z axis as the central axis when the XY plane is a horizontal plane and the Z axis is an axis vertically upward. It has an annular structure. The support is composed of support substrates 300 arranged below the detection ring 600 at predetermined intervals. When such an arrangement is adopted, the capacitance elements C1 to C4 are configured by fixing the individual displacement electrodes E2 to the lower surfaces of the detection units D1 to D4 and fixing the individual fixed electrodes E1 to the upper surface of the support substrate 300. Therefore, the work of adjusting the electrode spacing can be facilitated, and the production efficiency can be improved.

Further, in this basic embodiment, as shown in FIG. 17, the detection unit D has a first deformation portion 61 and a second deformation portion 62 that cause elastic deformation due to the action of a force or moment to be detected, and a second deformation portion 62. It has a deformed portion 61 of 1 and a displacement portion 63 that causes displacement due to elastic deformation of the second deformed portion 62. Here, the outer end of the first deformed portion 61 is connected to the connecting portion L adjacent thereto, and the inner end is connected to the displacement portion 63. Further, the outer end of the second deformed portion 62 is connected to the connecting portion L adjacent thereto, and the inner end 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 as in the example shown in FIG. 18, the displacement electrode E2 is formed on the lower surface of the displacement portion 63 to form the support substrate 300. If the fixed substrate E1 is formed on the upper surface, a capacitive element C composed of 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 carrying out 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 detection units D is provided.

However, since the axis component to be detected is limited by only one set of detection units D and sufficient detection accuracy cannot be obtained, practically, the number n of detection units D (the number n of detection points R) is used. It is preferable to set n ≧ 2 and 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 n detection units are arranged at each detection point. The detection ring is formed by alternately arranging the detection units D1, D2, ..., Dn and n connecting parts L1, L2, ..., Ln along the basic ring road B. Is preferable.

Further, in practical use, the number n of the detection units D is set to an even number, n even number of detection points are defined on the basic ring road B, and the detection units are arranged at each detection point to detect n even numbers. It is preferable to form the detection ring by alternately arranging the portions and the even number of n connecting portions along the basic ring road B. By providing an even number of n detection units, it is possible to form a basic structural 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 merit of eliminating the interference of the shaft component and simplifying the arithmetic processing performed by the detection circuit can be obtained.

In this case, when an even number of n connecting portions are numbered in order from a predetermined starting point along the basic ring road B, the action points Q1, Q2, ... Are arranged at the odd-numbered connecting portions. , It is preferable that the fixed points P1, P2, ... Are arranged at the 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 detection along the basic ring road B. The detection ring can be configured by arranging the parts D2 in this order. In this case, the point of action Q1 may be arranged in the first connecting portion L1 and the fixed point P1 may be arranged in the second connecting portion L2.

The force sensor according to the basic embodiment described in §3 is a more practical embodiment in which the number n of the 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 ° around the origin O, and the Y axis is counterclockwise 45 about the origin O. When the W axis is defined as the coordinate axis rotated by °, 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 a negative V. 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, counterclockwise along the basic ring road B, 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 The detection ring 600 is configured by arranging the detection unit D3 of 3, the fourth connecting unit L4, and the fourth detection unit 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 part L1), and the second point of action Q2 is on the negative X-axis (third connecting part). L3), the first fixed point P1 is located on the positive Y axis (second connecting portion L2), and the second fixed point P2 is located on the negative Y axis (fourth connecting portion L4). Is located in. In other words, the points of action Q1 and Q2 are arranged at the odd-numbered connecting portions, and the fixed points P1 and P2 are arranged at the even-numbered connecting portions.

Then, in the basic structure shown in FIG. 16, the first connecting member 410 that connects the position of the first working point Q1 of the detection ring 600 to the receiving body 100 and the second working point Q2 of the detection ring 600 A second connecting member 420 that connects the position to the 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 of the detection ring 600. A second fixing member 520 for fixing the position of the fixing point P2 to the support substrate 300 is provided. In such a basic structure unit, stress generated based on an external force acting on the receiving body 100 can be efficiently transmitted to four sets of detection units D1 to D4 in a state where the support substrate 300 is fixed.

As shown in FIG. 18, each detection unit D is formed with a capacitance element C in which the increase / decrease of the capacitance value is reversed when the compressive stress is applied and when the extension stress is applied along the basic ring road B. Has been done.

Therefore, the capacitance value of the first capacitance element C1 having the displacement electrode E2 (D1) fixed to the first detection unit D1 located at the first detection point R1 is set to C1 and the second detection point R2. The capacitance value of the second capacitance element C2 having the displacement electrode E2 (D2) fixed to the second detection section D2 located is transferred to C2 and the third detection section D3 located at the third detection point R3. The displacement electrode E2 (D4) fixed to the fourth detection unit D4 located at the fourth detection point R4 and the capacitance value of the third capacitance element C3 having the fixed displacement electrode E2 (D3). Assuming that the capacitance value of the fourth capacitance element C4 having the above 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 above formula, 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 a detection circuit that outputs an electric signal corresponding to the detected values Fz, Mx, My, and Mz based on such an operation. ..

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

For example, in the case of the embodiment shown in FIG. 16, the electrode spacing of the four sets of capacitive elements C1 to C4 is defined by the height dimension of the pair of fixing members 510 and 520, but in the manufacturing process. Even if there is an error in the height direction of the fixing members 510 and 520 due to dimensional error or temperature environment, the dimensional error can be offset by the difference calculation, so an accurate detection value that does not include the error is output. It becomes possible to do.

Generally speaking, with respect to a force or moment about a specific axis to be detected, some of the n plurality of detection units behave as the detection unit of the first attribute, and the other part behaves as the detection unit of the second attribute. It will behave as a detector of. Here, the detection unit of the first attribute means that when a positive component for a specific axis acts, the displacement unit 63 is displaced in a direction approaching the support substrate 300, and a negative component for the specific axis is generated. When acting, the displacement unit 63 is a detection unit having a property of being displaced in a direction away from the support substrate 300. On the contrary, in the detection unit of the second attribute, when a positive component for a specific axis acts, the displacement unit 63 is displaced in a direction away from the support substrate 300, and a negative component for the specific axis is generated. When acted on, the displacement unit 63 is a detection unit having a property of being displaced in a direction approaching the support substrate 300.

Then, when detecting the component for 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 the opposite positions of the support substrate 300 are used. The capacitance element composed of the fixed electrode E1 is called a first attribute capacitance element, and is located at a position opposite to the second attribute displacement electrode E2 fixed to the displacement portion 63 of the detection unit of the second attribute and the support substrate 300. If the capacitance element composed of the fixed second attribute fixed electrode E1 is called the second attribute capacitance element, the capacitance value of the first attribute capacitance element and the capacitance element of the second attribute capacitance element are determined by the detection circuit. An electric signal corresponding to the difference between the capacitance value and the capacitance value may be obtained and output as an electric signal indicating a detection component of the force or moment to be detected for the specific axis.

Of course, whether a specific capacitive element behaves as a first attribute capacitive element or a second attribute capacitive element is a matter that depends on a specific axial component that acts on it. Therefore, the 6-axis components Fx, Fy , Fz, Mx, My, and Mz act on each of the attributes. Specifically, with respect to a specific row of the table shown in FIG. 21, a capacitive element in which "+" or "++" is described is a first attribute capacitive element as long as it relates to a specific axial component corresponding to the row. Therefore, the capacitive element in which "-" or "---" is described is the second attribute capacitive element as far as the specific axial component corresponding to the row is concerned.

In consideration of such attributes, the addition / subtraction calculators 16, 17, and 18 shown in FIG. 23 have a capacitance value of the first attribute capacitance element and a capacitance value of the second attribute capacitance element with respect to a specific axis component. It means that the difference calculation for finding the difference between and is performed. Since only the calculation for obtaining the sum is performed on the addition / subtraction calculation unit 15, the error canceling function based on the difference calculation does not work.

<<< §5. Embodiment using 8 sets of detectors >>>
Subsequently, an embodiment (second embodiment) in which the number n of the detection points R is set to n = 8 and a total of eight sets of detection units are used will be described here. In the basic embodiment described in §3 (first embodiment), the number n of the detection points R is set to n = 4, and a total of four sets of detection units D1 to D4 are used. Since it is not possible to sufficiently detect Fy, an example of detecting the four-axis components Fz, Mx, My, and Mz using the approximation table shown in FIG. 21 has been described. In the embodiment using the eight sets of detection units described here, the manufacturing cost increases as the number of detection units increases, but all of the 6-axis components Fx, Fy, Fz, Mx, My, and Mz are practically used. The detection operation with sufficient accuracy becomes possible.

FIG. 24 is a bottom view of the detection ring 700 used for the force sensor according to the embodiment using the eight sets of detection units. As can be seen by comparing the detection ring 600 shown in FIG. 13 (c) with the detection ring 700 shown in FIG. 24, the only substantial difference between the two is the number of detection units 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 structure of the detection units D11 to D18 is the same as the structure of the detection unit D shown in FIG. FIG. 24 shows an example in which the detection unit D18 is composed of three plate-shaped pieces, a first deformed portion 71, a second deformed portion 72, and a displacement portion 73. The other detection units D11 to D17 also have a similar structure.

FIG. 25 is a top view showing the region distribution of the detection ring 700 shown in FIG. 24 (the mesh-like hatching is for showing the regions of the detection units D11 to D18, and does not show the cross section). As shown in the figure, the detection ring 700 has a structure in which eight sets of detection units D11 to D18 are connected by eight sets of connecting parts L11 to L18. While the detection units D11 to D18 are composed of three plate-shaped pieces, the connecting parts L11 to L18 are composed of thick members, and when an external force acts on the detection ring 700, the external force is concerned. The elastic deformation of the detection ring 700 based on the above is concentrated on the detection units 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, and the second connecting portion L11 are counterclockwise along the basic ring road B shown by the thick alternate long and short dash line in the figure. 2 detection unit D12, 3rd connection unit L13, 3rd detection unit D13, 4th connection unit L14, 4th detection unit D14, 5th connection unit L15, 5th detection unit D15, 6th The detection ring is arranged 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 in which the X-axis is rotated 45 ° counterclockwise around the origin O on the XY plane, and the Y-axis is rotated 45 ° counterclockwise around the origin O. The W axis is defined as the coordinate axis. <I>, <II>, <III>, and <IV> in the figure indicate the first to fourth quadrants in the XY two-dimensional coordinate system. Two sets of eight sets of detection units D11 to D18 are arranged in each quadrant.

FIG. 26 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 700 shown in FIG. 24. The basic ring road B shown by the thick alternate long and short dash 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 ring road B. In the figure, the positions of the inner contour line and the outer contour line of the detection ring 700 are shown by solid lines. In the case of the illustrated embodiment, the basic ring road 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 is a ring-thick portion (connecting portion L11) of the detection ring 700. It becomes the center line of ~ L18).

Eight sets of detection points R11 to R18 are arranged at equal intervals on the basic ring road B. As in the example shown in FIG. 26, in order to define eight detection points R11 to R18 at equal intervals on the basic circular path B composed of circles, the origin O is the starting point in the XY plane and the X-axis is positive. An azimuth vector Vec (θ) forming an angle θ counterclockwise with respect to the above is defined, and the i-th (however, 1 ≦ i ≦ 8) detection point R1i is set to the azimuth vector Vec (π / 8 + (i-1). ) ・ Π / 4) and the basic ring road B may be arranged at the intersection position. For example, the first detection point R11 shown in FIG. 26 is a direction vector Vec (θ) forming an angle θ counterclockwise with respect to the positive direction of the X axis and the basic ring road B, where θ = π / 8. It is located at the intersection.

In the figure, the VX axis is located between the X-axis and the V-axis, the VY axis is located between the V-axis and the Y-axis, the WY-axis is located between the Y-axis and the W-axis, and the X-axis and the W-axis are located. The WX axis is defined at the intermediate position. The eight sets of detection points R11 to R18 are eventually arranged in the positive and negative regions of the VX axis, the VY axis, the WY axis, and the WX axis. These detection points R11 to R18 indicate the arrangement of the detection units D11 to D18, respectively, and as shown in FIG. 25 as a mesh-like hatching region, the eight sets of detection units D11 to D18 each indicate eight sets of detection. 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 the detection ring 600 has 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 points fixed to the support substrate 300, and the four sets of action points Q11 to Q14 are points on which the force from the receiving body 100 acts.

As shown in FIG. 26, the first point of action Q11 is on the positive X-axis, the second point of action Q12 is on the positive Y-axis, the third point of action Q13 is on the negative X-axis, and the fourth point of action. 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. The fixed point P14 is located 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 and Y axes while the four points P11 to P14 on the V and W axes are fixed. Is detected based on the elastic deformation of eight sets of detection units D11 to D18 arranged at the detection points R11 to R18 on the VX axis, the VY axis, the WY axis, and the WX axis.

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

As can be seen by comparing FIGS. 25 and 26, the first point of action Q11 is arranged at the first connecting portion L11, the first fixed point P11 is arranged at the second connecting portion L12, and the second The point of action Q12 is arranged at the third connecting portion L13, the second fixed point P12 is arranged at the fourth connecting portion L14, the third point of action Q13 is arranged at the fifth connecting portion L15, and the third The fixed point P13 of 3 is arranged at the sixth connecting portion L16, the fourth working point Q14 is arranged at the seventh connecting portion L17, and the fourth fixed point P14 is arranged at the eighth connecting portion L18. There is.

Here, the positions of the four sets of fixing points P11 to P14 of the detection ring 700 are fixed to the support substrate 300 by the fixing member. In FIG. 24, the connection positions of the fixing members 560, 570, 580, and 590 for fixing the positions of the fixing points P11 to P14 are shown 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 receiving body 100 by the connecting member.

FIG. 27 is a top view of the basic structural part of the force sensor according to the embodiment using eight sets of detection parts. This basic structural part includes a receiving body 100, a detection ring 700, and a support substrate 300. Although not shown in the top view, the support substrate 300 is a disk-shaped member having the same diameter as the outer diameter of the receiving body 100, and is arranged below the receiving body 100 and the detection ring 700. .. The receiving body 100 is an annular member as in 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 receiving body 100 and the supporting substrate 300 shown in FIG. 27 are not essentially different from the receiving body and the supporting substrate in the embodiment shown in FIG. 16, they are shown by using the same reference numerals.

The main difference between the basic structure shown in FIG. 16 and the basic structure shown in FIG. 27 is that the former uses a detection ring 600 having four sets of detection units D1 to D4, whereas the latter uses a detection ring 600. , A detection ring 700 having eight sets of detection units D11 to D18 is used. Further, the difference accompanying this is that in the former, two sets of connecting members 410 and 420 and two sets of fixing members 510 and 520 are provided, whereas in the latter, four sets of connecting members 460 are provided. , 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 point of action Q11 is connected to the inner peripheral surface of the 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 near the second point of action Q12 is connected to the inner peripheral surface of the 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 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 near the fourth point of action Q14 is connected to the inner peripheral surface of the receiving body 100 by a fourth connecting member 490 arranged along the negative region of the Y axis. ing.

On the other hand, the lower surface of the position of the first fixing point P11 (position of the V-axis positive region) of the detection ring 700 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 of the position of the point P12 (the position of the positive region of the W axis) is fixed to the upper surface of the support substrate 300 by the second fixing member 570. Similarly, the lower surface of the position of the third fixing point P13 (position of the negative V-axis region) of the detection ring 700 is fixed to the upper surface of the support substrate 300 by the third fixing member 580, and the fourth of the detection ring 700. The lower surface of the position of the fixing point P14 (the position of the negative region of the W axis) 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 structural portion shown in FIG. 27. Here, the capacitive element is a displacement electrode E2 formed on the lower surface of each displacement portion 73 of the eight sets of detection portions D11 to D18 shown in FIG. 24, and a fixed electrode E1 formed at a position facing the upper surface of the support substrate 300. And are formed by. The detailed structure of such a capacitive element C has already been described in §3 with reference to FIG. According to this structure, a capacitive element is formed in which the increase / decrease of the capacitance value is reversed when the compressive stress is applied and when the tensile stress is applied along the basic ring road B. Here, the capacitance elements formed for the eight sets of detection units D11 to D18 are referred to as capacitance elements C11 to C18, respectively, and the capacitance values of each of these capacitance elements C11 to C18 are designated by the same reference numerals C11 to C18. I will show you.

Then, in a state where the support substrate 300 is fixed, the amount of fluctuation (increase / decrease) in the capacitance value of each of the capacitance elements C11 to C18 when an external force Fx, Fy, Fz, Mx, My, Mz is applied to the receiving body 100. Degree) is shown in the table of FIG. Also in this table, "+" indicates that the capacitance value increases (the electrode spacing of the capacitance element C decreases), and "-" indicates that the capacitance value decreases (the electrode spacing of the capacitance element C decreases). (Increases). In addition, "++" indicates that the degree of increase in the capacitance value is larger than that of "+", and "(+)" indicates that the degree of increase in the 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 in capacitance value is smaller than that of "-". Show that.

Although detailed explanation of the reason why the results shown in the table of FIG. 28 are obtained is omitted here, four sets of fixed points P11 to P14 (black circles) shown in FIG. 27 are fixed in position. How the displacement electrodes E2 of the detection units D11 to D18 are displaced in consideration of the deformation mode of the detection ring 700 when an external force in a predetermined direction acts on the positions of the action points Q11 to Q14 (white circles). It will be easy to understand if you consider it.

In the table of FIG. 28, the result of the Fx row and the Fy row 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, so that the displacement electrode E2 is not significantly displaced by the action of the forces Fx and Fy. On the other hand, the result of the Mx line and the My line is "++" or "---" (that is, the degree of increase or decrease is large) because the moments Mx and My are as shown in FIG. This is because when it acts, the detection ring is greatly tilted and the displacement electrode E2 is largely displaced.

The table of FIG. 28 shows the results when a positive force and a positive moment are applied, but when a negative force and a negative moment are applied, "+" and "-" are shown. Will be the result of reversal. Assuming the results shown in the table of FIG. 28, the 6-axis components Fx, Fy, Fz, Mx, My, and Mz of the external force acting on the receiving body 100 can be calculated by the arithmetic formula shown in FIG. 29. can.

First, the force Fx in the X-axis direction can be obtained by the calculation of Fx = −C11 + C12-C13 + C14 + C15-C16 + C17-C18 by referring to each column of the Fx row in the table of FIG. 28. Similarly, the force Fy in the Y-axis direction can be obtained by the calculation Fy = + C11-C12-C13 + C14-C15 + C16 + C17-C18 by referring to each column of the Fy row in the table of FIG. 28. Then, the force Fz in the Z-axis direction can be obtained by the calculation of Fz = − (C11 + C12 + C13 + C14 + C15 + C16 + C17 + C18) by referring to each column of the Fz row in the table of FIG. 28.

On the other hand, the moment Mx around 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 Mx row in the table of FIG. 28. Similarly, the moment My around the Y-axis can be obtained by the calculation My = + C11 + C12-C13-C14-C15-C16 + C17 + C18 by referring to each column of the My row in the table of FIG. 28. Then, the moment Mz around the Z axis can be obtained by the calculation of Mz = + C11-C12 + C13-C14 + C15-C16 + C17-C18 by referring to each column of the Mz row in the table of FIG. 28.

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. Therefore, if each calculation formula shown in FIG. 29 is used, the other axis components are almost canceled out, so that only the components that do not contain the other axis components can be obtained. Strictly speaking, however, the absolute values of the fluctuations indicated by (+) and (-), the absolute values of the fluctuations indicated by + and-, and ++ and-in the table of FIG. 28 are shown. The absolute values of the fluctuations do not exactly match. Therefore, it is difficult to completely eliminate the interference of other shaft components, but it can be suppressed to a level that does not cause any problem in practical use. Further, if necessary, it is also possible to perform a correction for removing the mixed other axis component by performing an operation using a microcomputer or the like. After all, if a detection circuit (not shown) that performs an operation based on the arithmetic expression shown in FIG. 29 is prepared, the voltage values corresponding to the 6-axis components Fx, Fy, Fz, Mx, My, and Mz can be used as an electric signal. Can be output.

In addition, although each of the calculation formulas shown in FIG. 29 performs the calculation using all eight sets of capacitance values C11 to C18, the calculation formula does not necessarily use all the capacitance values. It is not necessary, and only a part of it may be used.

For example, if only 4 of the 8 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. The force Fy can be calculated by the arithmetic formula Fy = + C11-C12-C13 + C14 or Fy = -C15 + C16 + C17-C18, and the force Fz is Fz =-(C11 + C14 + C15 + C18) or It can be calculated by the arithmetic formula Fz = − (C12 + C13 + C16 + C17).

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

FIG. 30 is a diagram showing variations of such an arithmetic expression. While each calculation formula shown in FIG. 29 is a calculation formula that utilizes all of the eight sets of capacitance values C11 to C18, in the variation shown in FIG. 30, eight sets of capacitance values C11 to C18 are used. It suffices to perform calculations using only four of these sets. Theoretically, it is possible to obtain a more accurate detection value by performing an calculation using all of the eight sets of capacitance values C11 to C18, but in reality, each calculation formula shown in FIG. 30 By performing the calculation based on, it is possible to obtain a detection result with sufficient accuracy in practical use. Therefore, if it is desired to reduce the calculation load of the detection circuit as much as possible, the variation shown in FIG. 30 may be adopted.

<<< §6. Embodiment to which auxiliary connection member is added >>>
Here, an embodiment (third embodiment) to which an auxiliary connecting member is added will be described. In §3, with respect to the force sensor according to the basic embodiment (first embodiment), when an external force of 6-axis components such as Fx, Fy, Fz, Mx, My, and Mz is applied, four sets of capacitance are applied. It has been stated that with respect to the capacitance values C1 to C4, the capacitance value fluctuates 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 shows that the degree of increase in the capacitance value is smaller than that of "" and "-".

As described above, the magnitude of the fluctuation generated in the four sets of capacitance values C1 to C4 differs depending on the acting external force component, and the detection sensitivity of each axis component is different. Therefore, for example, even if the four-axis components Fz, Mx, My, and Mz are detected based on the calculation formula shown in FIG. 22, the sensitivity of the detected values Mx and My is considerably higher than the sensitivity of the detected values Fz and Mz. Become. On the other hand, since the detection sensitivity of Fx and Fy is considerably low, in practice, as shown in the approximation table of FIG. 21, the fluctuation amount must be set to 0, and the detection value cannot be obtained.

Of course, the detection sensitivity can be adjusted by changing the dimensions of each part of the detection ring 600. For example, the thickness of the first deformed part 61 and the second deformed part 62 constituting the detection part D is reduced to reduce the 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 entire force sensor, it is not possible to correct the difference in the detection sensitivity of each axis component. In order to provide a force sensor capable of detecting a multi-axis component, it is not preferable that there is a difference in detection sensitivity. Here, a device for correcting such a difference in detection sensitivity will be described.

In the force sensor described so far, as a general tendency, the detection sensitivity of the components Mx and My is higher than the detection sensitivity 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 around the Y axis acts, as shown in FIG. 6, for example. Similarly, when a moment Mx around the X-axis acts, deformation is likely to occur.

FIG. 31 is a bottom view (upper view) of the basic structural portion of the force sensor according to the third embodiment, which has been devised to correct the difference in detection sensitivity in view of such structural features. It is a side sectional view (lower view) cut in the XZ plane. The bottom view shown in the upper row shows a state in which the support substrate 300 is removed for convenience.

The difference between the basic structural part according to the first embodiment shown in FIG. 16 and the basic structural part according to the third embodiment shown in FIG. 31 is that the auxiliary connecting members 531, 532 are added in the latter. Only. As shown in the lower side sectional view, the auxiliary connecting 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. Its upper end is connected to the lower surface of the detection ring 600, and its lower end is connected to the upper surface of the support substrate 300. Similarly, the auxiliary connection member 532 is a columnar member arranged at a position where the connection reference line A2, which passes through the point of action Q2 and is parallel to the Z axis, is the central axis, and its upper end 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, but in the third embodiment shown here, as a member for connecting the two, an auxiliary connecting member 531 and 531 are further connected. 532 will be added. Here, the fixing members 510 and 520 are connected to the positions of the fixed points P1 and P2, while the auxiliary connecting members 531 and 532 are connected to the positions of the working points Q1 and Q2. The pair of auxiliary connecting members 531, 532 functions to suppress the displacement of the detection ring 600 that occurs when the moment My or Mx acts on the receiving body 100.

FIG. 6 shows a deformation mode of the detection ring 200 when the moment My acts. However, if auxiliary connecting members 531, 532 are added to the positions of the action points Q1 and Q2, such deformation is suppressed. It will be easy to understand that it will be done. As described above, the auxiliary connecting members 531 and 532 have a function of suppressing deformation when the moment My acts, and further serve a function of suppressing deformation when the moment Mx acts. Of course, it also functions to suppress deformation when moment Mz, force Fx, Fy, and Fz act.

In short, the auxiliary connecting members 531, 532 function as "replacement rods" for maintaining a constant distance between the detection ring 600 and the support substrate 300 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, 532 is provided, a certain effect can be obtained, but in practice, it is preferable to provide both.

According to the experiment conducted by the inventor of the present application, the displacement suppressing effect of the auxiliary connecting members 531 and 532 is most remarkable with respect to the moment My and to some extent with respect to the moment Mx, but with respect to the forces Fx and Fy. Is few. This is because when the forces Fx and Fy are applied to the receiving body 100, the auxiliary connecting members 531 and 532 are inclined with respect to the connecting reference lines A1 and A2, but the auxiliary connecting members 531 and 532 are connected to the connecting reference lines. It is considered that this is because the displacement that inclines with respect to the connection reference lines A1 and A2 is more likely to occur than the displacement that expands and contracts in the direction along A1 and A2. As a result, the effect of correcting the difference between the detection sensitivity for the moments Mx and My and the detection sensitivity for the forces Fx and Fy can be obtained.

FIG. 32 shows the amount of fluctuation (increase / decrease) in the capacitance value of each capacitance element when a force in each axis direction or a moment around each axis acts on the receiving body 100 in the third embodiment shown in FIG. It is a table showing the degree). The symbols in each column are “+” or “−”, and it can be seen that the difference in the detection sensitivity of each axis component is significantly corrected when compared with the table shown in FIG.

Of course, since the symbols in the respective columns in these tables indicate the relative detection sensitivities, the addition of the auxiliary connecting members 531, 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 is lowered for all the axial components, but the detection sensitivity for the moments Mx and My is significantly lowered, and the detection sensitivity for the forces Fx and Fy is remarkable. Since the decrease in is slight, it means that the detection sensitivity for each axis component is balanced. In order to increase the detection sensitivity of the entire force sensor, as described above, the thickness of the first deformed portion 61 and the second deformed portion 62 constituting the detection unit 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 is the central axis, or the auxiliary connection member 532 may be arranged so that the connection reference line A4 shown in FIG. 31 is the central axis. You may. Here, the connection reference line A3 is a straight line that passes through the movement point in which the action point Q1 is moved in the positive direction of the X axis and is parallel to the Z 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 moving point and is parallel to the Z axis. The auxiliary connecting members arranged at the positions of the connecting reference lines A3 and A4 play a role of connecting the lower surface of the receiving body 100 and the upper surface of the connecting member 300.

Since the connection reference lines A1 to A4 are all straight lines orthogonal to the X-axis, if the auxiliary connecting member is arranged at this position, the detection sensitivity of the moment My, which has the highest detection sensitivity among the 6-axis components, is effective. It is possible to suppress it. Of course, the auxiliary connection member does not necessarily have to be arranged at an accurate position about the connection reference lines A1 to A4 as the central axis, and even if the auxiliary connection member is arranged at a position slightly deviated from the connection reference lines A1 to A4, the difference in detection sensitivity can be obtained. The effect of correction can be obtained.

After all, in order to correct the difference in detection sensitivity, the Z-axis passes through the points of action Q1 and Q2 or the moving points where the points of action Q1 and Q2 are moved along the line connecting the origin O and the points of action Q1 and Q2. Auxiliary connection members that define connection reference lines A1 to A4 parallel to the above and connect the lower surface of the detection ring 600 or the receiving element 100 and the upper surface of the support substrate 300 along the connection reference lines A1 to A4 or its vicinity. 531 and 532 may be provided.

Since the role of the auxiliary connecting members 531, 532 is to balance the detection sensitivity for each shaft component, it is necessary to maintain the detection sensitivity for the forces Fx and Fy as much as possible and reduce the detection sensitivity for the moment My. be. For that purpose, as the auxiliary connecting members 531 and 532, when the force acts in the direction orthogonal to the connecting reference lines A1 to A4 as compared with the case where the force acts in the direction along the connecting reference lines A1 to A4. However, it is preferable to use a member that easily causes elastic deformation. In other words, when a force in the direction parallel to the Z axis is applied, elastic deformation is unlikely to occur, but when a force is applied in the direction perpendicular to the Z axis, a member that is likely to cause elastic deformation is used. Is preferable.

The auxiliary connecting members 531, 532 shown in FIG. 31 are columnar members extending in the Z-axis direction, and have a property that they are difficult to expand and contract in the Z-axis direction, but are easily inclined in the Z-axis direction. , The material is suitable as an auxiliary connection member. Actually, the degree of elastic deformation may be adjusted by the thickness of the auxiliary connecting member. Of course, the shape of the auxiliary connecting member is not limited to the columnar shape, and any shape may be adopted.

Specifically, an elongated rod-shaped member made of a material having a certain degree of elasticity such as metal or resin may be used as the auxiliary connecting member 531 or 532, and this may be arranged along a predetermined connection reference line. Then, when the support substrate 300 is fixed and a force is applied to the receiving body 100 in the direction along the connection reference line, elastic deformation is unlikely to occur, and the force is applied in the direction orthogonal to the connection reference line. When acted, 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 be tilted as a whole. As a result, the displacement of the detection ring 600 in the Z-axis direction is effectively suppressed as compared with the displacement in the X-axis direction and the Y-axis direction, and the difference in detection sensitivity for each axis component can be corrected.

FIG. 33 is a partial cross-sectional view showing a modified example of the neighborhood structure of the auxiliary connecting member 532 shown in FIG. 31. In this modified example, the auxiliary connecting member 532 is devised to be more easily tilted, and a diaphragm structure is adopted at the connecting portions at both ends of the auxiliary connecting member.

Similar to the auxiliary connecting member 532 shown in FIG. 31, the auxiliary connecting member 532d shown in FIG. 33 is a columnar structure arranged so that the connection reference line A2 passing through the point of action Q2 is the central axis, and is detected. It serves to connect the ring 600 and the support substrate 300. However, the upper end of the auxiliary connecting 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 portion formed in the connecting portion L of the detection ring 600, and in order to form the 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 in order to form the diaphragm portion 300d, a groove portion G2 is formed on the upper surface of the support substrate 300.

FIG. 33 shows a structure in the vicinity of the auxiliary connecting member 532d having the connection reference line A2 as the central axis. 600d and 300d are formed. When such a connection structure using 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, as the auxiliary connecting members 531d and 532d, members having a large rigidity may be used. In order to secure a sufficient inclination angle, it is preferable to make the auxiliary connecting members 531d and 532d as long as possible.

In the example shown in FIG. 33, the upper end of the auxiliary connecting member 532d is connected to the detection ring 600 via the diaphragm portion 600d, and the lower end of the auxiliary connecting member 532d is connected to the support substrate 300 via the diaphragm portion 300d. Although it is adopted, a configuration in which only the upper end or only the lower end is connected via the diaphragm portion may be adopted.

After all, when the auxiliary connecting member is connected via the diaphragm portion, the connecting portion of the detection ring or the receiving body to the auxiliary connecting member, the connecting portion of the support substrate to the auxiliary connecting member, or these connecting portions. Both of them may be composed of a diaphragm portion, and the auxiliary connecting member may be inclined with respect to the connection reference line due to the deformation of the diaphragm portion based on the action of a force or a 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, FIG. Instead of the table of 20, the results shown in the table of FIG. 32 are obtained. However, based on the table of FIG. 32, accurate detection values without interference of other axis components cannot be obtained for all of the 6-axis components Fx, Fy, Fz, Mx, My, and Mz. Rather, it is not possible to perform an approximation in which the amount of change in the capacitance value when the forces Fx and Fy are applied is 0, so that the degree of interference of other axis components becomes large.

In order to obtain accurate detection values for all of the 6-axis components Fx, Fy, Fz, Mx, My, and Mz without interference of other axis components, the second embodiment described in §5 (8 sets of detection units) Auxiliary connection member may be added to the embodiment). Specifically, with respect to the basic structural portion according to the second embodiment shown in FIG. 27, the positions of the four sets of action points Q11 to Q14 (or the positions of the movement points obtained by moving them outward) are set to the positions. A connection reference line 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 play a role of connecting the lower surface of the connecting portion L of the detection ring 700 and the upper surface of the support substrate 300. Of course, if necessary, the upper end and the lower end of the auxiliary connecting member may be connected via a diaphragm portion as shown in FIG. 33.

FIG. 34 shows each capacitive element when a force in each axial direction or a moment around each axis acts on the force sensor to which four sets of auxiliary connecting members are added to the second embodiment described in §5. It is a table which shows the fluctuation amount (degree of increase / decrease) of a capacitance value. The symbols in each column are “+” or “−”, and it can be seen that the difference in the detection sensitivity of each axis component is significantly corrected when compared with the table shown in FIG. 28. In the second embodiment, as described in §5, interference of other axis components is eliminated for all of the 6-axis components Fx, Fy, Fz, Mx, My, and Mz by the calculation based on the calculation formula shown in FIG. The detected value can be obtained. Therefore, if four sets of auxiliary connecting members are added to the second embodiment, it is possible to accurately detect the 6-axis component 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 performing calculations using a microcomputer or the like. It is also possible to make a correction to remove other axis components.

It is not always necessary to use all four sets of auxiliary connecting 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 auxiliary connecting members are provided at the positions of the two sets of action points Q11 and Q13, respectively, the displacement when the moment My acts can be significantly suppressed. At least, it is possible to make corrections that reduce the detection sensitivity to the moment My.

<<< §7. Embodiment using a square detection ring >>>
All of the embodiments described so far have been force sensors having a circular shape in each part. 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 having a circle arranged on the XY plane with the Z axis as the central axis and the basic annular path B as the basic annular path B. The support body (support substrate) 300 is a circular plate-like structure arranged in the negative region of the Z axis with the Z axis as the central axis, and the 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 composed of a square member. For example, as the detection ring, a square detection ring 700S as shown in FIG. 35 can be used. The detection ring 700S is a square shape of the detection ring 700 shown in FIG. 24, and has a similar basic structure. Therefore, as the code of each part of the detection ring 700S shown in FIG. 35, S (an acronym for Square) is added to the end of the code of the corresponding part of the detection ring 700 shown in FIG. 24. Note that FIG. 24 is a bottom view, whereas FIG. 35 is a top view, so that the directions of the Y-axis are 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 shown in the figure, the first detection unit D11S has a first deformation unit 71S, a second deformation unit 72S, and a displacement unit 73S supported at both ends by these. The same applies to the structures of the second to eighth detection units D12S to D18S.

The basic structure and deformation mode of the detection units D11S to D18S are the same as the basic structure and deformation mode of the detection unit D shown in FIG. Of course, the shape of the detection unit formed on the circular detection ring 700 and the detection unit formed on the square detection ring 700S will be slightly different, but the essential structure and deformation mode will not change. .. Therefore, when the capacitance element C is formed by the displacement electrode E2 formed in the displacement portions 73S of the detection portions D11S to D18S and the fixed electrode E1 formed at the opposite positions of the support substrates, the capacitance element C is formed along the basic annular path BS. The increase / decrease in the capacitance value of the capacitive element C is reversed between when the compressive stress is applied and when the tensile stress is applied.

Although not shown here, the receiving body 100S made of a square annular structure surrounding the outer side of the square detection ring 700S is the same as the outer contour line of the receiving body 100S. A support (support substrate) 300S made of a plate-like structure having a square is prepared. That is, in the fourth embodiment described here, the detection ring 700S is an annular structure having a square arranged on the XY plane with the Z axis as the central axis as the basic ring road BS, and the support (support substrate) 300S. Is a square plate-like structure arranged in the negative region of the Z axis with the Z axis as the central axis, and the 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 receiving body 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 the second embodiment described in §5. In the case of this 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 receiving body 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-like hatching is for showing the regions of the detection units D11S to D18S, and does not show the cross section). As shown in the figure, the detection ring 700S has a structure in which eight sets of detection units D11S to D18S are connected by eight sets of connecting parts L11S to L18S. While the detection units D11S to D18S are composed of three plate-shaped pieces, the connecting portions L11S to L18S are composed of thick members, and when an external force acts on the detection ring 700S, the external force is concerned. The elastic deformation of the detection ring 700S based on the above is concentrated on the detection units D11S to D18S.

When a square basic ring road BS as shown by a thick alternate long and short dash line is defined in FIG. 36, the first connecting portion L11S, the first detecting portion D11S, and the second are used counterclockwise along the basic ring road BS. Connecting part L12S, 2nd detecting part D12S, 3rd connecting part L13S, 3rd detecting part D13S, 4th connecting part L14S, 4th detecting part D14S, 5th connecting part L15S, 5th The detection unit D15S, the sixth connection unit L16S, the sixth detection unit D16S, the seventh connection unit L17S, the seventh detection unit D17S, the eighth connection unit L18S, and the eighth detection unit D18S are arranged in this order. The detection ring 700S is configured by arranging it.

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

FIG. 37 is a plan view showing the basic ring road BS defined on the XY plane and each point defined on the basic ring road BS for the detection ring 700S shown in FIG. 35. The basic ring road BS shown by the thick alternate long and short dash line in the figure is a square centered on the origin O arranged on the XY plane, and the detection ring 700S is a square ring structure extending along the basic ring road BS. Become. In the figure, the positions of the inner contour line and the outer contour line of the detection ring 700S are shown by solid lines. In the case of the illustrated embodiment, the basic ring road BS is a square on the XY plane passing through the intermediate position between the inner contour line and the outer contour line of the detection ring 700S, and is a ring-thick portion (connecting portion L11S) of the detection ring 700S. ~ L18S) becomes the center line.

As can be seen from FIG. 37, in this fourth embodiment, the fixed point P and the action point Q are not provided between the detection points R11 and R12. Similarly, no fixed point P or 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 n connecting portions are numbered in order along the basic ring road, the action point Q and the fixed point P are both odd-numbered. The policy is adopted that the points of action Q and the fixed points P are arranged alternately along the basic ring road BS while being arranged at the connecting portion.

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 working 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 working point Q16 is arranged at the seventh connecting portion L17S. That is, the fixed points P15 and P16 and the points of action Q1 and Q2 are all arranged at the odd-numbered connecting portions and alternately, and the fixed points P are also the points of action at the even-numbered connecting portions. Q is also not placed.

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

More specifically, in the case of 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 point of action Q15. Is arranged on the positive Y-axis, and the second point of action 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 has a first side S1 extending in a direction parallel to the Y axis and intersecting the positive X axis, and an X axis. A second side S2 that extends in a direction parallel to the positive Y-axis and intersects a positive Y-axis, a third side S3 that extends in a direction parallel to the Y-axis and intersects a negative X-axis, and an extension in a direction parallel to the X-axis. It has a fourth side S4 that intersects the negative Y axis.

Then, the first detection point R11 is arranged at a position having a positive Y coordinate of the first side S1, and the second detection point R12 is arranged at a position having a positive X coordinate of the second side S2. The third detection point R13 is arranged at a position having a negative X coordinate of the second side S2, and the fourth detection point R14 is arranged at a position having a positive Y coordinate of the third side S3. The fifth detection point R15 is arranged at a position having a negative Y coordinate of the third side S3, and the sixth detection point R16 is arranged at a position having a negative X coordinate of the fourth side S4. The seventh detection point R17 is arranged at a position having a positive X coordinate of the fourth side S4, and the eighth detection point R18 is arranged at a position having a 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 the eight sets of detection points R11 to R18. Will be done. The amount of fluctuation (degree of increase / decrease) of the capacitance values C11 to C18 of the capacitance elements C11 to C18 when a force in each axial direction or a moment around each axis is applied to the force sensor is shown in the table of FIG. 38. It becomes something like the one shown in. Here, the column marked with "0" indicates that no significant fluctuation amount occurs, and the column marked with "+" or "-" indicates that the capacitance value increases or decreases. .. Further, the column marked with "++" or "---" indicates 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, and Mz of the external force acting on the receiving body 100S can be calculated by the arithmetic formula shown in FIG. 39. can.

First, the force Fx in the X-axis direction can be obtained by the calculation of Fx = + C12-C13-C16 + C17 by referring to each column of the Fx row in the table of FIG. 38. 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. 38. Then, the force Fz in the Z-axis direction can be obtained by the calculation of Fz = − (C11 + C12 + C13 + C14 + C15 + C16 + C17 + C18) by referring to each column of the Fz row in the table of FIG. 38.

On the other hand, the moment Mx around 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 Mx row in the table of FIG. 38. Similarly, the moment My around the Y-axis can be obtained by the calculation My = + C11 + C12-C13-C14-C15-C16 + C17 + C18 by referring to each column of the My row in the table of FIG. 38. Then, the moment Mz around the Z axis can be obtained by the calculation of Mz = −C11-C12 + C13 + C14-C15-C16 + C17 + C18 by referring to each column of the Mz row in the table of FIG. 38.

The basic structural part 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 each of the arithmetic expressions shown in FIG. 39, it is possible to obtain a detected value excluding the interference of other axis components. Although not shown here, if a detection circuit that performs an operation based on the arithmetic expression shown in FIG. 39 is prepared, the voltage values corresponding to the 6-axis components Fx, Fy, Fz, Mx, My, and Mz can be electrically generated. 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 performing calculations using a microcomputer or the like. It is also possible to make a correction to remove other axis components.

The calculation formula shown in FIG. 39 shows an example of a calculation formula for calculating each axis component, and it is also possible to calculate each axis component using another calculation formula. For example, the force Fz can be calculated by the formula Fz =-(C11 + C13 + C15 + C17) or Fz =-(C12 + C14 + C16 + C18), and the moment Mx can be calculated by the formula Mx = -C12-C13 + C16 + C17. The moment My can be calculated by the formula My = + C11-C14-C15 + C18, and the moment Mz can be calculated by the formula Mz = -C11 + C13-C15 + C17 or Mz = -C12 + C14-C16 + C18. Is possible.

FIG. 40 is a diagram showing variations of such an arithmetic expression. Theoretically, it is possible to obtain a more accurate detection value by performing an operation using all of the eight sets of capacitance values C11 to C18, but in reality, each of them shown as a variation in FIG. 40. Even if the calculation is performed based on the calculation formula, it is possible to obtain a detection result with sufficient accuracy in practical use. Therefore, if it is desired 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. Deformation example in which the positions of the action point and fixed point are changed>
FIG. 41 is a top view of the basic structure of the force sensor according to the fifth embodiment of the present application. Similar to the second embodiment shown in FIG. 27, the fifth embodiment is a force sensor in which each part has a circular shape and eight sets of detection parts D11 to D18 are used. The basic structure of the force sensor according to the fifth embodiment shown in FIG. 41 is almost the same as the basic structure of the force sensor according to the second embodiment shown in FIG. 27, and is actually the detection ring 700. The same members are used for the receiving body 100 and the supporting substrate 300. Therefore, the structure and arrangement of the eight sets of detection units D11 to D18 are the same, and the structure and arrangement of the eight sets of capacitive elements are also the same.

That is, in the basic structure shown in FIG. 41, the detection ring 700 is a circular annular structure arranged in the XY plane with the origin O as the center, and in the XY plane, the origin O is the starting point in the positive direction of the X axis. On the other hand, when the orientation vector Vec (θ) forming an angle θ counterclockwise is defined, the i-th (however, 1 ≦ i ≦ 8) detection point is the orientation vector Vec (π / 8 + (i-1). ) ・ Π / 4) is located at the intersection of the basic ring road B. This is a structure common to the basic structure shown in FIG. 27. The difference between the two is the positions of the point of action Q and the fixed point P, and the configuration of the detection circuit (calculation formula 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 Y-axis, and four sets of fixed points P11 to P14 (black circles) are on the V-axis or W-axis. Is located in. Therefore, the detection ring 700 is connected to the receiving body 100 by four sets of connecting members 460, 470, 480, 490, and is connected to the support substrate 300 by 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 arranged on the X axis. Have been placed. Therefore, the detection ring 700 is connected to the receiving body 100 by two sets of connecting members 470 and 490, and is connected to the support substrate 300 by 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 the force sensor according to the second embodiment shown in FIG. 27, but has an action 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. 35. In the fourth embodiment, when an even number of n connecting portions are numbered in order along the basic ring road BS, the action point Q and the fixed point P are both arranged at the odd-numbered connecting portions. In addition, the policy is adopted that the action points Q and the fixed points 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 policy, both the action point Q and the fixed point P are arranged on the V axis and the W axis. Not placed.

Therefore, the variation mode of the capacitance values of the eight sets of capacitance elements C11 to C18 in the force sensor according to the fifth embodiment is different from the table shown in FIG. 28 (table for the second embodiment). The calculation formula used for detecting each axis component is also different from the calculation formula shown in FIG. 29 (the calculation formula for the second embodiment). Although the description of the table showing the variation mode of the capacitance value and the calculation formula used for detecting each axis component according to the fifth embodiment is omitted here, in reality, the table and the figure shown in FIG. 38 are shown. An equation close to the arithmetic expression shown in 39 can be obtained.

As described above, even when the detection rings having exactly the same physical structure are used when carrying out the present invention, the deformation mode of the detection ring differs depending on the positions of the action point Q and the fixed point P, and each of them is different. It should be noted that the calculation formula for obtaining the axis component also differs.

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

FIG. 42 is a top view (upper view) of the basic structural portion of the force sensor according to the sixth embodiment of the present invention and a side sectional view (lower view) obtained by cutting the basic structure portion in the XZ plane. The detection ring 700 in the basic structure portion shown in FIG. 42 is exactly the same as the detection ring 700 in the basic structure portion according to the second embodiment shown in FIG. 27, and has the structure of eight sets of detection units D11 to D18. There is no difference in the arrangement, the structure and 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, while the receiving body 100 shown in FIG. 27 is an annular structure arranged outside the detection ring 700, the receiving body 150 shown in FIG. 42 is arranged inside the detection ring 700. It is 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 of the second embodiment, but the detection ring 700 is attached to the receiving body 150. Four sets of connecting members 465,475,485,495 for connecting 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 receiving body 150, the inner peripheral surface of the detection ring 700 and the receiving body 150 It is provided as a member that connects to the outer peripheral surface.

As can be seen from the lower side sectional view of FIG. 42, since the receiving body 150 is housed inside the detection ring 700, the support substrate 380 is a disk having an outer diameter equal to the outer diameter of the detection ring 700. It is composed of shaped members. Therefore, the size of the basic structural portion in the radial direction can be set small. In the illustrated example, since the thickness of the receiving body 150 is set to be larger than the thickness of the detection ring 700, the structure is such that the upper end of the receiving body 150 protrudes upward, but it is desired to reduce the overall thickness. In this case, the thickness of the receiving body 150 may be equal to the thickness of the detection ring 700.

By adopting a structure in which the receiving body 150 is housed inside the detection ring 700 as described above, the inner cavity portion of the detection ring 700 can be effectively used, and the device can be miniaturized. However, since the detection ring 700, which is deformed when subjected to the action of an external force, is exposed to the outside, when the portion of the detection ring 700 comes into contact with some object, the original deformation of the detection ring 700 (described above). The deformation required for the detection principle) is hindered, and correct detection results cannot be obtained. Therefore, when adopting the sixth embodiment, it is preferable to give consideration such as providing a protective cover on the outside so that the original deformation of the detection ring 700 is not hindered.

Since the detection operation of each axis 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, the description thereof is omitted here.

<8-3. Deformation example in which the receiving body is placed above>
Although §8-2 described a modified example in which the receiving body is arranged inside the detection ring, the arrangement of the receiving body is not limited to the outside or the inside of the detection ring. Theoretically, any position can be obtained as long as the receiving body can transmit the force or moment to be detected to the action point Q of the detection ring without interfering with the original deformation of the detection ring. It may be placed in a position. Here, a modified example in which the receiving body is arranged above the detection ring will be described.

FIG. 43 is a top view (upper view) of the basic structural portion of the force sensor according to the seventh embodiment of the present invention and a side sectional view (lower view) obtained by cutting the basic structure portion in the XZ plane. The detection ring 700 and the support substrate 380 in the basic structure shown in FIG. 43 are exactly the same as the detection ring 700 and the support substrate 380 in the basic structure according to the sixth embodiment shown in FIG. 42, and there are four sets. The arrangement of the fixing members 560, 570, 580, 590 is the same.

However, while the receiving body 150 shown in FIG. 42 is a columnar structure arranged inside the detection ring 700, the receiving body 180 shown in FIG. 43 is arranged above the detection ring 700. It is a disk-shaped structure. In the case of this example, the receiving body 180 is composed of a disk-shaped member having an outer diameter equal to the outer diameter of the detection ring 700, that is, a member having exactly 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 attached to the receiving body 180. Four sets of connecting members 491, 492, 49, 494 for connecting are provided above the detection ring 700. As shown by the broken line in the upper part of FIG. 43, the four sets of connecting members 491, 492, 49, 494 are columnar 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 for connecting the upper surface of the detection ring 700 and the lower surface of the force receiving body 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 vertically upward, the detection ring 700 is arranged on the XY plane and the support (support substrate 380). ) Are arranged below the detection ring 700 at predetermined intervals, and the receiving body 180 is arranged above the detection ring at predetermined intervals.

As described above, even when the receiving body 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. Since the detection operation of each axis component in the force sensor according to the seventh embodiment is the same as the operation of the force sensor according to the second embodiment described in §5, the description thereof is omitted here.

<8-4. Other variants regarding the shape and arrangement of the receiving body and support>
In the first to fifth embodiments described so far, the receiving body 100 made of an annular structure is used, but this is a convenience for arranging the receiving body 100 outside the detection ring. On the other hand, the receiving body 150 (FIG. 42) used in the sixth embodiment described in §8-2 has a columnar shape, and the receiving body 180 (FIG. 42) used in the seventh embodiment described in §8-3 has a columnar shape. 43) has a disk shape. As described above, the shape of the receiving body may be an annular structure or a plate-shaped 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-like structure are used as the support, but the support in the present invention plays a role of supporting the detection ring. Any member that fulfills the above requirements is sufficient, and the shape may be arbitrary. Therefore, it does not necessarily have to be a plate-like structure, and an annular structure can be used as a support.

Further, in the first to seventh embodiments described so far, the support (support substrate 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 a plane), and it can be arranged at an arbitrary position. However, if the support is composed of a support substrate arranged below the detection ring, a fixed electrode can be formed on the upper surface thereof. Therefore, in order to simplify the manufacturing process, a plate arranged below the detection ring It is preferable that the support is composed of a shaped structure.

<8-5. Variations of detector>
Here, variations regarding the structure of the detection unit D will be described. In all 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 deformed portion 61 and a second deformed portion 62 that cause elastic deformation, and a displacement portion 63 that causes displacement due to the elastic deformation of these deformed portions 61 and 62.

More specifically, as shown in FIG. 17A, 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 cause elastic deformation. Both ends are composed of a third plate-shaped piece 63 supported by these plate-shaped pieces 61 and 62, and the third plate-shaped piece 63 functions as a displacement portion. Here, when a 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 a 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 maintained in parallel.

Here, focusing on the planar shape of the detection unit in the embodiments shown in FIGS. 13, 16, 27, 27, 31, 41, and 42 described so far, the first plate-shaped piece 61, The projected images of the 71 and the second plate-shaped pieces 62, 72 and the third plate-shaped pieces 63, 73 on the XY plane have a fan shape close to a trapezoid, 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, and 63 constituting 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 according to 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, and 73S constituting the detection unit D11S are all rectangular. This is because the detection ring 700S has a square ring shape, and the detection units D11S to D18S are designed according to this square ring.

As described above, in the examples described so far, the planar shape of each plate-shaped piece constituting the detection unit is designed to be fan-shaped or rectangular according to the shape of the detection ring, but each plate-shaped piece is designed. It is not always necessary to use the plane shape of the above properly as in the above example. For example, as shown in FIG. 13 (c), even when the annular detection ring 600 is adopted, the plan shape of each of the plate-shaped pieces 61, 62, and 63 is designed to be rectangular. It doesn't matter. In the embodiment shown in FIG. 13 (c), if the planar shape of the plate-shaped pieces 61, 62, 63 is made rectangular like the plate-shaped pieces 71S, 72S, 73S shown in the embodiment of FIG. 35, the detection unit 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 sensors.

The detection unit D having a cross-sectional structure illustrated in FIG. 17A is one of the detection units having the most preferable structure in carrying out the present invention, but 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 variations in the structure of the detection unit D.

The detection unit DB shown in FIG. 44A is a detection unit provided in a part of the detection ring 600B, and is a first plate-shaped piece 61B, a second plate-shaped piece 62B, a displacement portion 63B, and a first plate-shaped piece 61B. 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 arranged so as to be parallel to the XY plane (the plane including the basic ring road B). The first plate-shaped piece 61B and the second plate-shaped piece 62B, which are constituent elements, are plates 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 as to be opposite to each other, but the detection shown in FIG. 44 (a) In the case of the part DB, the first plate-shaped piece 61B and the second plate-shaped piece 62B are in a state of being parallel to each other. Therefore, in this detection unit DB, the first plate-shaped piece 61B and the second plate-shaped piece 62B are inclined with respect to the normal N regardless of whether the compressive force f1 is applied or the stretching force f2 is applied. Therefore, in either case, the displacement portion 63B moves to the upper part of the figure. Therefore, it is not possible to detect the direction of the acting force or moment by increasing or decreasing the capacitance value of the capacitance element C, but if the application has a fixed direction of the acting force or moment, the detection unit DB acts. It is possible to detect the magnitude of the applied force or moment.

The detection unit DC shown in FIG. 44B is a detection unit provided in a part of the detection ring 600C, and is a first plate-shaped piece 61C, a second plate-shaped piece 62C, a displacement part 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 arranged so as to be parallel to the XY plane (the plane including the basic ring road B). The first plate-shaped piece 61C and the second plate-shaped piece 62C are plate-shaped components arranged so as to be inclined so as to be opposite to each other with respect to the normal line N. However, the mode of inclination is different from that of the detection unit D shown in FIG. 17 (a), and the distance between the plate-shaped pieces 61C and 62C increases toward the lower part of the figure.

In this detection unit DC, the displacement unit 63C moves to the upper part of the figure when the compressive force f1 acts, and the displacement part 63C moves to the lower part of the figure when the extension force f2 acts. Although the direction of displacement is opposite to that of the detection unit D shown in FIG. 17 (a), the direction and magnitude of the applied force and moment can be detected by increasing or decreasing the capacitance value of the capacitance 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 deformed portion 80. The plate-shaped deformed portion 80 is a component that causes elastic deformation by the action of a force or moment to be detected, and the plate surface is arranged so as to be inclined with respect to an XY plane (a plane including the basic ring road B). Has been done. In this detection unit DD, when a compressive force f1 or an extension force f2 acts, the plate-shaped deformed portion 80 is bent.

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

Of course, as the detection unit D, those having various structures can be adopted. The detection unit used in the present invention is, in short, any structure as long as it has a structure in which displacement or bending occurs when a compressive force f1 or an extension force f2 acts in a direction along the basic ring road B. It doesn't matter if there is one. On the other hand, the connecting portion may have a certain degree of flexibility, but it is preferable that the connecting portion is not deformed as much as possible in order to cause the detection portion to be effectively deformed by the applied external force. Therefore, in practice, at least a part of the detection unit is an elastic deformed body that causes elastic deformation that can be significantly detected by the detection element, and the connecting part is a rigid body in which significant deformation is not detected in the detection sensitivity of the detection element. Is preferable.

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

FIG. 45 is a top view of the basic structural portion of the force sensor according to the modified example in which the detection ring 800 in which the orientation of the detection portion is changed is used instead of the detection ring 600 in the first embodiment shown in FIG. (Figure) and a side sectional view (lower figure) of this cut along the XZ plane. The four sets of detection units D1 to D4 provided in the detection ring 600 shown in FIG. 16 are replaced with four sets of detection units D1'to D4' in the detection ring 800 shown in FIG. 45. Here, the basic structure of the four sets of detection units D1'to D4' is similar to the structure of the detection unit D shown in FIG. 17 (a), but the orientation on the detection ring is different.

As can be seen from the detection unit D1'in FIG. 45, the detection unit D1' has a first plate-shaped piece 91 and a second plate-shaped piece 92 that cause elastic deformation, and these plate-shaped pieces 91 at both ends. It is composed of a third plate-shaped piece 93 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 unit 63 is located below the detection ring 600, and the lower surface of the displacement unit 63 is the upper surface of the support substrate 300. Facing. On the other hand, in the four sets of detection units D1'to D4' provided in the detection ring 800 shown in FIG. 45, the displacement portion 93 is located outside the detection ring 800, and the outer surface of the displacement portion 93. Faces the inner peripheral surface of the 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 ring road B as the rotation axis. have. Therefore, when the compressive force f1 acts along the basic ring road B, the displacement portion 93 is displaced outward (see FIG. 17B), and when the extension force f2 acts along the basic ring road B, the displacement portion 93 is displaced. Displaces 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 unit 63 is displaced in the Z-axis direction, whereas the displacement unit 63 is provided in the detection ring 800 shown in FIG. 45. In the four sets of detection units D1'to D4', the displacement unit 93 is displaced in the radial direction of the circle drawn on the XY plane with the origin O as the center. 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 receiving body 100 facing the displacement electrode E2, the pair of electrodes E1 , E2 can form the capacitive element C. Then, the capacitance value of the capacitance 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 sets of capacitance elements C1 to C4 is different, the variation form of the capacitance value of the four sets of capacitance elements C1'to C4' is different from that shown in the table of FIG. However, if a table such as the table in FIG. 20 is created as a table showing the variation form of the capacitance values of the four sets of capacitance elements C1'to C4', each axis component of the force or moment to be detected can be obtained. The calculation formula to be calculated can be derived.

Here, with respect to the force sensor shown in FIG. 45, the description of a specific calculation formula for calculating each axis component is omitted, but the modified example 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 related to the Z-axis direction. The illustrated example is an example in which the change in the electrode spacing of the capacitive element occurs in the radial direction, but of course, 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 a capacitive element is used as the detection element, the displacement electrode E2 needs to be provided in the detection unit (that is, the detection ring), but the fixed electrode E1 facing the displacement electrode E2 is not necessarily supported. It is not necessary to provide it on the body (support substrate 300), and it may be provided on the 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 modified example shown in FIG. 45, the fixed electrode E1 is not the support substrate 300. , Is provided on the inner peripheral surface of the annular receiving body 100. Here, the receiving body 100 is displaced by the action of an external force, and as a result, the fixed electrode E1 may also 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 receiving body 100 based on the variation form of the capacitance value of each capacitance element C1'to C4'.

<8-6. Deformation example using strain gauge>
In the embodiments described so far, a capacitance element is used as a detection element for detecting elastic deformation generated in the detection unit, but in carrying out the present invention, the detection element is not necessarily limited to the capacitance element. do not have. Here, as a detection element, a strain gauge fixed at a position where elastic deformation occurs in the detection unit is used, and as a detection circuit, an electric signal indicating an acting force or moment is transmitted based on the fluctuation of the electric resistance of the strain gauge. A modified example using the output circuit is shown.

FIG. 46 is a partial cross-sectional view showing the mode of elastic deformation of the plate-shaped deformed portion 80 constituting the detection portion DD shown in FIG. 44 (c). FIG. 46A shows a state in which no external force is applied to the detection unit DD. As shown in the figure, the detection unit DD is composed of a plate-shaped deformation unit 80 that elastically deforms due to the action of a force or moment to be detected. Here, the plate-shaped deformed portion 80 is arranged so that its plate surface is inclined with respect to the basic ring road B. In reality, such detection units DD are arranged at a plurality of locations on the detection ring 600D. In other words, the detection ring 600D is an annular structure in which a plurality of plate-shaped deformed portions 80 and a plurality of connecting portions L are alternately arranged.

Now, consider a 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 deformed portion 80 is bent, but the stress indicated by “−” or “+” in the figure is generated in each portion of the surface thereof. Here, "+" indicates a compressive stress (that is, a stress in the direction of contraction along the basic ring road B), and "-" indicates an extension stress (that is, a stress in the direction of expanding to the left and right of the figure along the basic ring road B). Stress) is shown. As shown in the figure, the stress generated on the surface of the plate-shaped deformed portion 80 is concentrated in the vicinity of the connection end of the plate-shaped deformed portion 80 with respect 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 a sign opposite to that in FIG. 46 (b) is obtained.

On the other hand, FIG. 46 (c) shows the stress distribution generated when a vertical force is applied to a pair of adjacent connecting portions L. Specifically, in the illustrated example, when the downward force f3 in the figure acts on the left connecting portion L and the upward force f4 in the figure acts on the right connecting portion L. It shows the stress distribution that occurs in. In this case as well, the stress generated on the surface of the plate-shaped deformed portion 80 is concentrated in the vicinity of the connection end of the plate-shaped deformed portion 80 with respect to the connecting portion L.

Considering such a stress distribution, in order to detect the elastic deformation caused in the detection unit DD by the strain gauge by using the detection unit DD including the plate-shaped deformation unit 80 as shown in the figure, the plate-shaped deformation unit 80 is used. It can be seen that effective detection is possible by arranging each strain gauge on both sides in the vicinity of the connection end with respect to the connection portion L of the above.

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. (Fig. (B)). When the detection ring is circular, the basic ring road B forms a circle, but in FIG. 47, a part of the basic ring road B is shown by a straight line for convenience of explanation.

As shown in the figure, with respect to the plate-shaped deformed portion 80 constituting the detection portion DD, the first strain gauge r1 is attached to the front surface near the first connection end with respect to the left connecting portion L, and the second strain gauge r1 is attached to the back surface. Strain gauge r2 is attached. Similarly, the third strain gauge r3 is attached to the front surface near the second connection end with respect to the right connecting portion L, and the fourth strain gauge r4 is attached to the back surface.

FIG. 48 is a circuit diagram showing a bridge circuit 19 that outputs an electric signal based on the detection results of the four sets of strain gauges r1 to r4 shown in FIG. 47. Specifically, in this bridge circuit 19, the first strain gauge r1 and the fourth strain gauge r4 are the first opposite sides, and the second strain gauge r2 and the third strain gauge r3 are the second sides. The circuit has opposite sides, 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 may be deformed as shown in FIG. 46 (b) or may be deformed as 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 axial component is omitted, the stress distribution generated on the surface of the detection unit is actually measured or simulated. The effective arrangement of the strain gauges can be determined by the above, and the detection value of the desired axial component can be obtained by performing a predetermined arithmetic process based on the bridge voltage of the bridge circuit composed of these strain gauges. It can be obtained as an electrical 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 around an arbitrary coordinate axis in an XYZ three-dimensional Cartesian coordinate system. Moreover, since high production efficiency can be realized, it can be used for measuring forces and moments in various industrial devices. In particular, in industrial equipment that automatically assembles using a robot arm, it is most suitable for applications in which it is incorporated into the joint portion of the arm, the force generated at the tip of the arm is monitored, and the force is controlled.

11-14: C / V conversion circuit 15-18: Addition / subtraction calculator 19: Bridge circuit 61, 61B, 61C: First deformation part 62, 62B, 62C: Second deformation part 63, 63B, 63C: Displacement part 64B, 64C: First bridge portion 65B, 65C: Second bridge portion 71, 71S: First deformed portion 72, 72S: Second deformed portion 73, 73S: Displacement portion 80: Plate-shaped deformed portion 91: First deformed portion 92: Second deformed portion 93: Displacement portion 100: Receiving body 150: Receiving body 180: Receiving body 200: Detection ring 300: Support substrate 300d: Diaphragm part 350: Fixing auxiliary body 380: Support board 410, 420: Connecting member 460, 465: Connecting member 470, 475: Connecting member 480, 485: Connecting member 490-495: Connecting member 510, 515, 516: Fixing member 520, 525, 526: Fixing member 531 532,532d: Auxiliary connecting members 560, 570, 580, 590: Fixing members 600, 600B, 600C, 600D: Detection ring 600d: Displacement 700, 700S: Detection ring 800: Detection rings A1, A2: Connection reference line B, BS: Basic loop path C, C1 to C4, C11 to C18: Capacitive element (its capacitance value)
D, D1 to D4, D11 to D18, D11S to D18S, DB, DC, DD, D1'to D4': Detection units d1 to d8: Facing surface distance 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: Force in X-axis direction Fy: Force in Y-axis direction Fz: Z-axis direction Force f1: Compressing force f2: Stretching force f3, f4: Vertical force in the figure G1, G2: Grooves H1, H2: Voids I1, I2: Insulating layers L, L1 to L4, L11 to L18, L11S ~ L18S: Connecting part Mx: Moment around X-axis My: Moment around Y-axis Mz: Moment around Z-axis N: Normal line O: XYZ Origins of three-dimensional coordinate system P1, P2, P11-P16: Fixed points Q1, Q2, Q11 to Q16: points of action R1 to R4, R11 to R18: detection points / measurement points r1 to r4: strain gauges S1 to S4: each side of the rectangular detection ring 700S T1 to T6: output terminal U: vertical surface V: Axis with the X axis rotated 45 ° counterclockwise on the XY plane VX: Coordinate axis located between the V axis and the X axis VY: Coordinate axes located between the V axis and the Y axis V1 to V4 : Voltage W: Axis in which the Y axis is rotated counterclockwise by 45 ° on the XY plane WX: Coordinate axis located between the W axis and the X axis WY: Coordinate axis X located between the W axis and the Y axis : XYZ 3D coordinate system coordinate axis Y: XYZ 3D coordinate system coordinate axis Z: XYZ 3D coordinate system coordinate axis

Claims (3)

A force sensor that detects a force or moment related to at least one of the forces in each coordinate axis direction and the moments around each coordinate axis in the XYZ three-dimensional Cartesian coordinate system.
A receiving body that is affected by a force or moment to be detected and is formed in a ring shape when viewed from the Z-axis direction along the Z-axis .
A support that supports the receiving body and
A detection unit that is connected between the receiving body and the supporting body and has a portion that is elastically deformed by the action of a force or moment to be detected, and the receiving force when viewed from the Z-axis direction. The detector located inside the body and
A detection element that detects elastic deformation generated in the detection unit, and
Based on the detection result of the detection element, a detection circuit that outputs an electric signal indicating a force or moment acting on one of the receiving body and the supporting body when a load is applied to the other, and a detection circuit.
With
One end of the detector is connected before Symbol support, the other end of the detector is connected before Symbol force receiving member,
The detection unit has a first deformation portion, a second deformation portion, and a displacement portion.
The first deformed portion and the second deformed portion are connected via the displacement portion.
When viewed from the Z-axis direction, the displaced portion can be displaced in the radial direction of the receiving body, and the wall thickness of the displaced portion is the wall thickness of the first deformed portion and the second. Thicker than the thickness of the deformed part of
The detection element is composed of a capacitance element having a displacement electrode fixed to the displacement portion and a fixed electrode fixed to the force receiving body and located at a position facing the displacement electrode.
When viewed from the Z-axis direction, the displacement electrode is located outside the displacement portion, and the fixed electrode is located inside the force receiving body.
The detection circuit is a force sensor characterized by outputting an electric signal indicating an acting force or moment based on a fluctuation in the capacitance value of the capacitance element. In the force sensor according to claim 1,
A force sensor characterized in that the first deformed portion and the second deformed portion are composed of plate-shaped pieces. In the force sensor according to claim 1 or 2.
A force sensor characterized in that the displacement electrode is fixed to a flat surface of the displacement portion.

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