JP2017062147A - Force sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To notify abnormality to the outside when it occurs.SOLUTION: A diaphragm part 120 is provided inside a toric support part 110. An external force acting on a force receiving part 210 is applied to the center of the diaphragm part 120 via a force conveyance part 220. Four detection points P21-P24 are defined on a detection reference circle G1 at the bottom face of the diaphragm part 120. A-system displacement electrodes E21A-E24A are disposed on the outside of the detection points P21-P24, and B-system displacement electrodes E21B-E24B are disposed in the inside. An A-system capacitive element is formed by the A-system displacement electrodes E21A-E24A and fixed electrodes E11A-E14A that face the foregoing, and a B-system capacitive element is formed by the B-system displacement electrodes E21B-E24B and fixed electrodes E11B-E14B that face the foregoing. When a difference between a detection value obtained from the A-system capacitive element and a detection value obtained from the B-system capacitive element exceeds a tolerance, a difference error is outputted.SELECTED DRAWING: Figure 16

Description

  The present invention relates to a force sensor that detects an external force, and more particularly, to a force sensor that detects a predetermined direction component of an applied external force by electrically detecting bending or displacement generated in an elastically deformable portion.

  Various types of force sensors are used to control the operation of robots and industrial machines. In order to reduce the size and reduce the cost, the force sensor used for such an application has a simple structure as much as possible, and can detect the force relating to each coordinate axis in a three-dimensional space independently. It is hoped that.

  In order to meet such requirements, a detection structure provided with a part of the elastic deformation part is prepared, and a predetermined direction of the applied external force is detected by electrically detecting deflection or displacement generated in the elastic deformation part. A force sensor for detecting a component has been proposed. For example, the following Patent Documents 1 and 2 disclose a force sensor that detects a deflection generated in the diaphragm portion using a piezoresistive element, and Patent Document 3 discloses a displacement generated in the diaphragm portion as a capacitance. A force sensor that detects using an element is disclosed. Further, Patent Document 4 discloses a force sensor that uses a piezoresistive element to detect bending generated in four bridge portions having a beam structure instead of a diaphragm portion.

  On the other hand, based on the same principle, there has also been proposed a force sensor that divides the applied external force into a translational force in the direction of each coordinate axis and a moment around each coordinate axis and can independently detect a total of six axis components. For example, in Patent Document 5, an external force is transmitted to four sets of localized diaphragms via four columnar force transmission bodies, and a displacement mode of each localized diaphragm is detected by a capacitive element, whereby a six-axis component of the external force is obtained. Has been disclosed. Patent Document 6 discloses a force sensor that can be used as a torque sensor by specializing in detecting moments around one axis.

Japanese Patent Laid-Open No. 3-202778 Japanese Patent Laid-Open No. 4-084725 JP 2010-008343 A JP 2004-066945 A JP 2004-325367 A JP 2012-037300 A

  In recent years, the demand for life support robots and medical support robots has been increasing toward a rapidly aging society, and it is expected that the spread of robots will not only extend to the industrial world, but also to the general public. Thus, in a society where humans and robots coexist, it is extremely important to ensure the safety of the robots sufficiently so that the robots do not harm humans.

  On the other hand, a force sensor is indispensable for controlling the operation of the robot, and the operation failure of the force sensor becomes a factor that impairs the safety of the robot. In particular, if an abnormality occurs in a force sensor incorporated in a life support robot or medical support robot, the robot cannot operate normally, and there is a possibility of causing harm to a care recipient or patient.

  However, as described above, the conventional force sensor disclosed in each of the above-mentioned patent documents electrically detects bending and displacement generated in the elastically deforming portion by a detecting element such as a piezoresistive element or a capacitive element. For this reason, it is difficult to eliminate all the failure factors such as breakage of the detection element, disconnection of the signal line, and malfunction of the signal processing circuit. In addition, these force sensors continue to output some detection value even when an abnormality occurs, so that if the robot controller cannot recognize the abnormality, the robot will malfunction. May harm people.

  Therefore, an object of the present invention is to provide a force sensor that can notify the outside when an abnormality occurs.

(1) A first aspect of the present invention provides a force sensor for detecting a predetermined direction component of an applied external force,
An elastic deformation part that generates elastic deformation by the action of a force, a support part that supports the elastic deformation part, a force receiving part that receives an external force to be detected, and an external force applied to the force receiving part A structure for detection having a force transmitting portion for transmitting to a predetermined location;
N A-line detection elements for electrically detecting deflection or displacement generated in the first vicinity of a plurality of n detection points defined at predetermined positions of the elastic deformation portion;
n number of B system detection elements for electrically detecting deflection or displacement generated in a second vicinity portion different from the first vicinity portion of the n detection points;
Provided,
For any i (1 ≦ i ≦ n), the i-th A-line detection element electrically detects the deflection or displacement of the first vicinity of the i-th detection point, and the i-th B The system detection element is configured to electrically detect deflection or displacement of the second vicinity of the i-th detection point,
Furthermore,
A system signal processing means for outputting an A system detection value indicating a predetermined direction component of the external force applied to the force receiving portion based on electrical detection signals detected by the n A system detection elements;
B system signal processing means for outputting a B system detection value indicating a predetermined direction component of the external force applied to the force receiving portion based on the electrical detection signals detected by the n B system detection elements;
The A system detection value and the B system detection value are compared, a difference d between them is obtained, and a predetermined calculation value calculated based on the A system detection value or the B system detection value or both is output as the final detection value. And a comparison means for outputting a difference error when the difference d exceeds a predetermined allowable value T;
Is provided.

(2) According to a second aspect of the present invention, in the force sensor according to the first aspect described above,
When the XYZ three-dimensional orthogonal coordinate system is defined, the detection structure is
Consists of an elastically deformable portion constituted by a thin-plate-like diaphragm portion extending along an XY plane or a plane parallel to the XY plane with the Z axis as a central axis, and an annular structure that supports and fixes the periphery of the elastically deformable portion A lower structure having a support portion;
A force receiving portion constituted by a plate-like substrate disposed so that the Z-axis becomes a central axis at a predetermined distance above the elastic deformation portion, and a lower surface center of the force receiving portion and an upper surface center of the elastic deformation portion. An upper structure having a force transmission portion connected along the Z-axis;
Is provided.

(3) According to a third aspect of the present invention, in the force sensor according to the first aspect described above,
When the XYZ three-dimensional orthogonal coordinate system is defined, the detection structure is
An elastic deformation portion having a central portion located on the Z axis, and a plurality of thin plate-like bridge portions extending radially from the central portion along a plane parallel to the XY plane or the XY plane; A lower structure having a support portion configured by an annular structure that supports and fixes the surroundings;
A force receiving portion constituted by a plate-like substrate disposed at a predetermined distance above the elastically deforming portion so that the Z axis becomes the central axis, and the center of the lower surface of the force receiving portion and the upper surface of the central portion are connected to the Z axis. An upper structure having a force transmission portion connected along
Is provided.

(4) According to a fourth aspect of the present invention, in the force sensor according to the third aspect described above,
The elastically deforming portion includes a thin plate-like first bridge portion extending from the center portion toward the X-axis positive direction, a thin plate-like second bridge portion extending from the center portion toward the X-axis negative direction, and a Y-axis extending from the center portion. A thin plate-like third bridge portion extending in the positive direction and a thin plate-like fourth bridge portion extending in the Y-axis negative direction from the central portion are provided.

(5) According to a fifth aspect of the present invention, in the force sensor according to the first aspect described above,
When the XYZ three-dimensional orthogonal coordinate system is defined, the detection structure is configured by a substrate extending along the XY plane or a plane parallel to the XY plane with the Z axis as a central axis, and the lower structure An upper structure disposed above the body,
A thin plate-like localized diaphragm portion extending in a direction along an XY plane or a plane parallel to the XY plane is formed at a plurality of m locations on the substrate constituting the lower structure. The part of the localized diaphragm part of the set constitutes the elastic deformation part, and the other part constitutes the support part,
The upper structure includes a force receiving portion constituted by a plate-like substrate arranged so that the Z axis is a central axis at a predetermined distance above the substrate constituting the lower structure, and a lower surface of the force receiving portion. And m sets of force transmission portions that connect a predetermined portion and the center of the upper surface of the m sets of diaphragm portions.

(6) According to a sixth aspect of the present invention, in the force sensor according to the fifth aspect described above,
By setting m = 4, a thin plate-like localized diaphragm portion extending in a direction along the XY plane or a plane parallel to the XY plane is formed at four locations on the substrate constituting the lower structure, The lower surface of each localized diaphragm is included in a common detection reference plane,
The upper structure includes a force receiving portion configured by a plate-like substrate disposed at a predetermined distance above the substrate constituting the lower structure so that the Z axis is the central axis, and a lower surface of the force receiving portion. 4 sets of force transmission parts connecting the upper surfaces of the 4 sets of localized diaphragm parts,
Of the four sets of force transmission units, the first force transmission unit is configured to follow a predetermined position on the lower surface of the force receiving unit and a first localized diaphragm unit along a straight line parallel to the Z axis that intersects the positive X axis. The second force transmission unit is connected to a predetermined position on the lower surface of the force receiving unit and the second localized diaphragm unit along a straight line parallel to the Z axis intersecting the negative X axis. The third force transmission unit connects the center of the upper surface, and the third force transmission unit has a predetermined position on the lower surface of the force receiving unit and the upper surface of the third localized diaphragm unit along a straight line parallel to the Z axis that intersects the positive Y axis. The fourth force transmission unit is connected to the center of the upper surface of the fourth localized diaphragm unit along a straight line parallel to the Z axis that intersects the negative Y axis. Are connected to each other.

(7) The seventh aspect of the present invention is the force sensor according to the second to sixth aspects described above,
When a detection reference plane is defined on the XY plane or a plane parallel to the XY plane and a detection reference circle centered on the Z-axis is drawn on this detection reference plane, all n detection points are on the detection reference circle. It is made to arrange in.

(8) The eighth aspect of the present invention is the force sensor according to the seventh aspect described above,
For each detection point, when the side far from the Z axis is called the outside and the side close to the Z axis is called the inside, for any i (1 ≦ i ≦ n),
The i-th A-system detection element electrically detects a deflection or a displacement in the vicinity of the outside of the i-th detection point,
The i-th B system detection element is configured to electrically detect bending or displacement in the vicinity of the inside of the i-th detection point.

(9) The ninth aspect of the present invention is the force sensor according to the first to eighth aspects described above,
Based on both electrical detection signals detected by some or all of the n A-system detection elements and electrical detection signals detected by some or all of the n B-system detection elements An auxiliary system signal processing means for outputting an auxiliary system detection value indicating a predetermined direction component of the external force applied to the force receiving unit,
In addition to the difference d between the A system detection value and the B system detection value, the comparison means further includes a difference dA between the A system detection value and the auxiliary system detection value and a difference dB between the B system detection value and the auxiliary system detection value. When any of the differences d, dA, and dB exceeds a predetermined allowable value T, a difference error is output.

(10) According to a tenth aspect of the present invention, in the force sensor according to the ninth aspect described above,
When dA <dB, the comparison means outputs the A system detection value as the final detection value, when dA> dB, the B system detection value is output as the final detection value, and when dA = dB, the A system detection value. Alternatively, the B system detection value is output as the final detection value.

(11) An eleventh aspect of the present invention is the force sensor according to the ninth or tenth aspect described above,
When two of the differences d, dA, and dB exceed a predetermined allowable value T, the comparison unit estimates a detection value that is involved in the calculation of the two differences as a false detection value. Exception processing is performed in which a predetermined calculated value calculated based on one or both of two detected values excluding the detected value is output as a final detected value.

(12) The twelfth aspect of the present invention is the force sensor according to the first to eighth aspects described above,
The comparison means determines whether or not the A system detection value and the B system detection value are within a predetermined allowable range, and outputs a range-out error when exceeding the allowable range. is there.

(13) According to a thirteenth aspect of the present invention, in the force sensor according to the twelfth aspect described above,
The comparison means outputs the B system detection value as the final detection value when only the A system detection value exceeds the allowable range, and the A system detection value when only the B system detection value exceeds the allowable range. Is output as the final detection value, and when both the A system detection value and the B system detection value exceed the allowable range, a predetermined dummy value within the allowable range is output as the final detection value. .

(14) According to a fourteenth aspect of the present invention, in the force sensor according to the first to eighth aspects described above,
The comparison means calculates an average value of the A system detection value and the B system detection value, and outputs the average value as a final detection value.

(15) According to a fifteenth aspect of the present invention, in the force sensor according to the first to fourteenth aspects described above,
For any i (1 ≦ i ≦ n)
The i-th A-system detection element is constituted by a piezoresistive element arranged in the first vicinity of the i-th detection point, and indicates a detection signal indicating a deflection occurring in the vicinity as a change in electric resistance value. Output
The i-th B system detection element is constituted by a piezoresistive element arranged in the second vicinity of the i-th detection point, and indicates a detection signal indicating a deflection occurring in the vicinity as a change in electric resistance value. Is output.

(16) According to a sixteenth aspect of the present invention, in the force sensor according to the first to fourteenth aspects described above,
For any i (1 ≦ i ≦ n)
The i-th A-system detection element is disposed so as to face the i-th A-system displacement electrode disposed in the first vicinity of the i-th detection point and the i-th A-system displacement electrode. Detecting the displacement generated in the first vicinity portion as a change in capacitance value, comprising an i-th A-system fixed electrode having an i-th A-system fixed electrode fixed to the support portion Output signal,
The i-th B system detection element is disposed so as to face the i-th B system displacement electrode disposed in the second vicinity of the i-th detection point and the i-th B system displacement electrode. A detection unit configured to include a displacement of the second neighboring portion as a change in capacitance value. A signal is output.

(17) According to a seventeenth aspect of the present invention, in the force sensor according to the second or fourth aspect described above,
When the detection reference plane is defined on the upper surface or the lower surface of the diaphragm section or each bridge section, and the X-axis projection image and the Y-axis projection image obtained by projecting the X axis and the Y axis onto the detection reference plane are defined,
By setting n = 4, four detection points are defined on the detection reference plane, and when the detection reference circle centered on the Z axis is drawn on the detection reference plane, the first detection point Is located at the intersection of the positive X-axis projection image and the detection reference circle, the second detection point is located at the intersection of the negative X-axis projection image and the detection reference circle, and the third detection point is positive. The fourth detection point is located at the intersection of the negative Y-axis projection image and the detection reference circle,
For each detection point, when the side far from the Z axis is called the outside, the side near the Z axis is called the inside,
The first A-line detection element electrically detects a deflection or a displacement generated in the vicinity of the outside of the first detection point, and the first B-line detection element is the first detection point. Electrically detecting deflections or displacements that occur in the vicinity of the inside,
The second A-line detection element electrically detects deflection or displacement generated in the vicinity of the outside of the second detection point, and the second B-line detection element is the second detection point. Electrically detecting deflections or displacements that occur in the vicinity of the inside,
The third A-line detection element electrically detects a deflection or a displacement that has occurred in the vicinity of the outside of the third detection point, and the third B-line detection element is the third detection point. Electrically detecting deflections or displacements that occur in the vicinity of the inside,
The fourth A-line detection element electrically detects a deflection or a displacement that has occurred in the vicinity of the outside of the fourth detection point, and the fourth B-line detection element is the fourth detection point. In this way, the deflection or displacement generated in the vicinity of the inside is electrically detected.

(18) According to an eighteenth aspect of the present invention, in the force sensor according to the seventeenth aspect described above,
Each detection element is composed of a piezoresistive element embedded in the upper surface or the lower surface of the diaphragm part or each bridge part, and each piezoresistive element outputs a deflection generated at the embedded position as a change in electric resistance value. Has function,
The first A-system detection element is composed of a piezoresistive element R1A arranged along the X-axis projection image outside the first detection point, and the first B-system detection element is the first It consists of a piezoresistive element R1B arranged along the X-axis projection image inside the detection point,
The second A-system detection element is composed of a piezoresistive element R2A arranged along the X-axis projection image outside the second detection point, and the second B-system detection element is the second It consists of a piezoresistive element R2B arranged along the X-axis projection image inside the detection point,
The third A-line detection element is composed of a piezoresistive element R3A arranged along the Y-axis projection image outside the third detection point, and the third B-line detection element is the third It consists of a piezoresistive element R3B arranged along the Y-axis projection image inside the detection point,
The fourth A-system detection element is composed of a piezoresistive element R4A arranged along the Y-axis projection image outside the fourth detection point, and the fourth B-system detection element is the fourth This is composed of a piezoresistive element R4B arranged along the Y-axis projection image inside the detection point.

(19) According to a nineteenth aspect of the present invention, in the force sensor according to the eighteenth aspect described above,
When the resistance values of the eight sets of piezoresistive elements R1A to R4A and R1B to R4B are expressed as R1A to R4A and R1B to R4B, respectively,
A system signal processing means uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (R1A + R2A + R3A + R4A)
MxA = K2A × (R3A-R4A)
MyA = K3A × (R1A-R2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are obtained. A system detection value is output,
The B system signal processing means uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (R1B + R2B + R3B + R4B)
MxB = K2B × (R3B-R4B)
MyB = K3B × (R1B-R2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X axis, and the moment component MyB around the Y axis are obtained. The B system detection value shown is output.

(20) According to a twentieth aspect of the present invention, in the force sensor according to the seventeenth aspect described above,
Each detection element is constituted by a capacitive element having a displacement electrode fixed to the upper surface or the lower surface of the diaphragm portion or each bridge portion, and a fixed electrode fixed to the support portion so as to face the displacement electrode. Each capacitive element has a function of outputting a displacement generated at a position where the displacement electrode is fixed as a change in capacitance value,
The first A-system detection element is composed of a capacitive element C1A arranged outside the first detection point, and the first B-system detection element is arranged inside the first detection point. A capacitor element C1B,
The second A-line detection element is composed of a capacitive element C2A arranged outside the second detection point, and the second B-line detection element is arranged inside the second detection point. A capacitor element C2B,
The third A-line detection element is composed of a capacitive element C3A arranged outside the third detection point, and the third B-line detection element is arranged inside the third detection point. Capacitance element C3B,
The fourth A-system detection element is composed of a capacitive element C4A arranged outside the fourth detection point, and the fourth B-system detection element is arranged inside the fourth detection point. The capacitor C4B is used.

(21) According to a twenty-first aspect of the present invention, in the force sensor according to the twentieth aspect described above,
When the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B using the same reference numerals,
A system signal processing means uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are obtained. A system detection value is output,
The B system signal processing means uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X axis, and the moment component MyB around the Y axis are obtained. The B system detection value shown is output.

(22) According to a twenty-second aspect of the present invention, in the force sensor according to the second or fourth aspect described above,
When the detection reference plane is defined on the upper surface or the lower surface of the diaphragm section or each bridge section, and the X-axis projection image and the Y-axis projection image obtained by projecting the X axis and the Y axis onto the detection reference plane are defined,
By setting n = 4, four detection points are defined on the detection reference plane, and when the detection reference circle centered on the Z axis is drawn on the detection reference plane, the first detection point Is located at the intersection of the positive X-axis projection image and the detection reference circle, the second detection point is located at the intersection of the negative X-axis projection image and the detection reference circle, and the third detection point is positive. The fourth detection point is located at the intersection of the negative Y-axis projection image and the detection reference circle,
The first A-system detection element electrically detects a displacement of the first detection point in the vicinity where the Y coordinate value is negative, and the first B-system detection element is the first Electrically detecting the displacement of the second detection point in the vicinity where the Y coordinate value is positive,
The second A-line detection element electrically detects a displacement of the second detection point in the vicinity where the Y coordinate value is negative, and the second B-line detection element is the second Electrically detecting the displacement of the second detection point in the vicinity where the Y coordinate value is positive,
The third A system detection element electrically detects a displacement of the third detection point in the vicinity where the X coordinate value is negative, and the third B system detection element is the third Electrically detecting the displacement of the first detection point in the vicinity where the X coordinate value is positive,
The fourth A-line detection element electrically detects a displacement of the fourth detection point in the vicinity where the X coordinate value is negative, and the fourth B-line detection element is the fourth The displacement generated in the vicinity of the first detection point in the vicinity where the X coordinate value is positive is detected electrically.

(23) According to a twenty-third aspect of the present invention, in the force sensor according to the twenty-second aspect described above,
Each detection element is constituted by a capacitive element having a displacement electrode fixed to the upper surface or the lower surface of the diaphragm portion or each bridge portion, and a fixed electrode fixed to the support portion so as to face the displacement electrode. Each capacitive element has a function of outputting a displacement generated at a position where the displacement electrode is fixed as a change in capacitance value,
The first A-system detection element is composed of a capacitive element C1A arranged in the vicinity of the first detection point where the Y coordinate value is negative, and the first B-system detection element is the first detection point. Consisting of a capacitive element C1B arranged in the vicinity of the detection point at which the Y coordinate value is positive,
The second A-system detection element includes a capacitive element C2A arranged in the vicinity of the second detection point where the Y coordinate value is negative, and the second B-system detection element is the second detection point. Consisting of a capacitive element C2B arranged in the vicinity of the detection point of which the Y coordinate value is positive,
The third A-system detection element is composed of a capacitive element C3A arranged in the vicinity of the third detection point where the X coordinate value is negative, and the third B-system detection element is the third detection point. Consisting of a capacitive element C3B arranged in the vicinity of the detection point of which the X coordinate value is positive,
The fourth A-system detection element is composed of a capacitive element C4A arranged in the vicinity of the fourth detection point where the X coordinate value is negative, and the fourth B-system detection element is the fourth detection point. The detection point is composed of a capacitive element C4B arranged in the vicinity of the positive X coordinate value.

(24) According to a twenty-fourth aspect of the present invention, in the force sensor according to the twenty-third aspect described above,
When the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B using the same reference numerals,
A system signal processing means uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are obtained. A system detection value is output,
The B system signal processing means uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X axis, and the moment component MyB around the Y axis are obtained. The B system detection value shown is output.

(25) According to a twenty-fifth aspect of the present invention, in the force sensor according to the twenty-fourth aspect described above,
Using predetermined signed proportional coefficients K2C, K3C,
MxC = K2C × ((C1A + C2A) − (C1B + C2B))
MyC = K3C × ((C3B + C4B) − (C3A + C4A))
The auxiliary system detection value indicating the moment component MxC around the X-axis and the moment component MyC around the Y-axis of the external force applied to the force receiving portion is output by performing the following computation processing or signal processing corresponding to the computation processing. It further has auxiliary system signal processing means,
In addition to the difference d between the A system detection value and the B system detection value, the comparison means further includes a difference dA between the A system detection value and the auxiliary system detection value and a difference dB between the B system detection value and the auxiliary system detection value. When any of the differences d, dA, and dB exceeds a predetermined allowable value T, a difference error is output.

(26) According to a twenty-sixth aspect of the present invention, in the force sensor according to the sixth aspect described above,
When an X-axis projection image and a Y-axis projection image obtained by projecting the X axis and the Y axis onto the detection reference plane are defined, and a detection reference circle centered on the Z axis is drawn on the detection reference plane,
By setting n = 4, one detection point is defined at the center of the lower surface of each localized diaphragm portion, and the first detection point is located at the intersection of the positive X-axis projection image and the detection reference circle. And the second detection point is located at the intersection of the negative X-axis projection image and the detection reference circle, and the third detection point is located at the intersection of the positive Y-axis projection image and the detection reference circle, The fourth detection point is located at the intersection of the negative Y-axis projection image and the detection reference circle,
For each detection point, when the side far from the Z axis is called the outside, the side near the Z axis is called the inside,
The first A-line detection element electrically detects a displacement generated in the vicinity of the outside of the first detection point, and the first B-line detection element is located inside the first detection point. The electrical displacement is detected in the vicinity of
The second A-line detection element electrically detects a displacement generated in the vicinity of the outside of the second detection point, and the second B-line detection element is located inside the second detection point. The electrical displacement is detected in the vicinity of
The third A-line detection element electrically detects a displacement generated in the vicinity of the outside of the third detection point, and the third B-line detection element is located inside the third detection point. The electrical displacement is detected in the vicinity of
The fourth A-line detection element electrically detects a displacement generated in the vicinity of the outside of the fourth detection point, and the fourth B-line detection element is located inside the fourth detection point. The displacement generated in the vicinity of is electrically detected.

(27) According to a twenty-seventh aspect of the present invention, in the force sensor according to the twenty-sixth aspect described above,
Each detection element is composed of a capacitive element having a displacement electrode fixed to the lower surface of each localized diaphragm portion and a fixed electrode fixed to the support portion so as to face the displacement electrode. , Having a function of outputting the displacement generated at the position where the displacement electrode is fixed as a change in capacitance value,
The first A-system detection element is composed of a capacitive element C1A arranged outside the first detection point, and the first B-system detection element is arranged inside the first detection point. A capacitor element C1B,
The second A-line detection element is composed of a capacitive element C2A arranged outside the second detection point, and the second B-line detection element is arranged inside the second detection point. A capacitor element C2B,
The third A-line detection element is composed of a capacitive element C3A arranged outside the third detection point, and the third B-line detection element is arranged inside the third detection point. Capacitance element C3B,
The fourth A-system detection element is composed of a capacitive element C4A arranged outside the fourth detection point, and the fourth B-system detection element is arranged inside the fourth detection point. The capacitor C4B is used.

(28) According to a twenty-eighth aspect of the present invention, in the force sensor according to the twenty-seventh aspect described above,
When the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B using the same reference numerals,
A system signal processing means uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are obtained. A system detection value is output,
The B system signal processing means uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X axis, and the moment component MyB around the Y axis are obtained. The B system detection value shown is output.

(29) According to a twenty-ninth aspect of the present invention, in the force sensor according to the sixth aspect described above,
When an X-axis projection image and a Y-axis projection image obtained by projecting the X axis and the Y axis onto the detection reference plane are defined, and a detection reference circle centered on the Z axis is drawn on the detection reference plane,
By setting n = 4, one detection point is defined at the center of the lower surface of each localized diaphragm portion, and the first detection point is located at the intersection of the positive X-axis projection image and the detection reference circle. And the second detection point is located at the intersection of the negative X-axis projection image and the detection reference circle, and the third detection point is located at the intersection of the positive Y-axis projection image and the detection reference circle, The fourth detection point is located at the intersection of the negative Y-axis projection image and the detection reference circle,
The first A-system detection element electrically detects a displacement of the first detection point in the vicinity where the Y coordinate value is negative, and the first B-system detection element is the first Electrically detecting the displacement of the second detection point in the vicinity where the Y coordinate value is positive,
The second A-line detection element electrically detects a displacement of the second detection point in the vicinity where the Y coordinate value is negative, and the second B-line detection element is the second Electrically detecting the displacement of the second detection point in the vicinity where the Y coordinate value is positive,
The third A system detection element electrically detects a displacement of the third detection point in the vicinity where the X coordinate value is negative, and the third B system detection element is the third Electrically detecting the displacement of the first detection point in the vicinity where the X coordinate value is positive,
The fourth A-line detection element electrically detects a displacement of the fourth detection point in the vicinity where the X coordinate value is negative, and the fourth B-line detection element is the fourth The displacement generated in the vicinity of the first detection point in the vicinity where the X coordinate value is positive is detected electrically.

(30) According to a thirtieth aspect of the present invention, in the force sensor according to the twenty-ninth aspect described above,
Each detection element is composed of a capacitive element having a displacement electrode fixed to the lower surface of each localized diaphragm portion and a fixed electrode fixed to the support portion so as to face the displacement electrode. , Having a function of outputting the displacement generated at the position where the displacement electrode is fixed as a change in capacitance value,
The first A-system detection element is composed of a capacitive element C1A arranged in the vicinity of the first detection point where the Y coordinate value is negative, and the first B-system detection element is the first detection point. Consisting of a capacitive element C1B arranged in the vicinity of the detection point at which the Y coordinate value is positive,
The second A-system detection element includes a capacitive element C2A arranged in the vicinity of the second detection point where the Y coordinate value is negative, and the second B-system detection element is the second detection point. Consisting of a capacitive element C2B arranged in the vicinity of the detection point of which the Y coordinate value is positive,
The third A-system detection element is composed of a capacitive element C3A arranged in the vicinity of the third detection point where the X coordinate value is negative, and the third B-system detection element is the third detection point. Consisting of a capacitive element C3B arranged in the vicinity of the detection point of which the X coordinate value is positive,
The fourth A-system detection element is composed of a capacitive element C4A arranged in the vicinity of the fourth detection point where the X coordinate value is negative, and the fourth B-system detection element is the fourth detection point. The detection point is composed of a capacitive element C4B arranged in the vicinity of the positive X coordinate value.

(31) According to a thirty-first aspect of the present invention, in the force sensor according to the thirtieth aspect described above,
When the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B using the same reference numerals,
A system signal processing means uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are obtained. A system detection value is output,
The B system signal processing means uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X axis, and the moment component MyB around the Y axis are obtained. The B system detection value shown is output.

(32) According to a thirty-second aspect of the present invention, in the force sensor according to the thirty-first aspect described above,
Using predetermined signed proportional coefficients K2C, K3C,
MxC = K2C × ((C1A + C2A) − (C1B + C2B))
MyC = K3C × ((C3B + C4B) − (C3A + C4A))
The auxiliary system detection value indicating the moment component MxC around the X-axis and the moment component MyC around the Y-axis of the external force applied to the force receiving portion is output by performing the following computation processing or signal processing corresponding to the computation processing. It further has auxiliary system signal processing means,
In addition to the difference d between the A system detection value and the B system detection value, the comparison means further includes a difference dA between the A system detection value and the auxiliary system detection value and a difference dB between the B system detection value and the auxiliary system detection value. When any of the differences d, dA, and dB exceeds a predetermined allowable value T, a difference error is output.

  In the force sensor according to the present invention, a plurality of n detection points are defined at predetermined positions of the elastically deforming portion of the detection structure, and in order to detect deflection or displacement generated in the vicinity of these individual detection points. The two detection elements of the A system detection element and the B system detection element are provided, and two detection values are obtained. If the difference between the two detection values exceeds a predetermined allowable value, a difference error is output. Therefore, when any abnormality occurs, the abnormality can be notified as a difference error.

FIG. 2 is a side sectional view of a general detection structure used for a force sensor (FIG. (A)) and a top view of the lower structure 100 (FIG. (B)). It is a sectional side view which shows a deformation | transformation state when force -Fz and moment + My act with respect to the force receiving part 210 of the structure for a detection shown in FIG. FIG. 10 is a side sectional view (FIG. (A)) of another detection structure used in the force sensor and a top view (FIG. (B)) of the lower structure 100 ′. FIG. 2 is a side sectional view (FIG. (A)) showing a conventional force sensor incorporating a piezoresistive element as a detection element in the detection structure shown in FIG. 1 and a top view (FIG. (B)) of a lower structure 100. . FIG. 5 is a side sectional view showing the principle of detection of force −Fz and moment + My by the force sensor shown in FIG. 4. FIG. 2 is a side sectional view (FIG. (A)) showing a conventional force sensor in which a capacitive element is incorporated as a detection element in the detection structure shown in FIG. 1 and a bottom view (FIG. (B)) of a lower structure 100. FIG. 7 is a side sectional view showing the principle of detection of a force −Fz and a moment + My by the force sensor shown in FIG. 6. FIG. 5 is a table showing a change in resistance value of each piezoresistive element R1 to R4 in the force sensor shown in FIG. 4 and a calculation formula for obtaining a predetermined direction component of an applied external force. It is a figure which shows the arithmetic expression which calculates | requires the table | surface which shows the capacitance value change of each capacitive element C1-C4 in the force sensor shown in FIG. 6, and the predetermined direction component of the applied external force. It is a top view which shows arrangement | positioning of each detection element D1-D4 in the force sensor shown in FIG. 4 and FIG. It is a figure which shows the computing equation which calculates | requires the predetermined direction component of the applied external force using the detection signal values D1-D4 obtained from the detection elements D1-D4 shown in FIG. It is a block diagram which shows the difference of the basic composition of the conventional force sensor and the force sensor which concerns on this invention. It is a top view which shows arrangement | positioning of each detection element D1A-D4A, D1B-D4B in the force sensor which concerns on this invention. It is a figure which shows the arithmetic expression which calculates | requires the table | surface which shows the change of the detection signal obtained from detection element D1A-D4A, D1B-D4B shown in FIG. 13, and the predetermined direction component of the applied external force. FIG. 1 is a side sectional view showing a force sensor according to the present invention in which a piezoresistive element is incorporated as a detection element in the detection structure shown in FIG. 1 (FIG. 1A), and a top view of a lower structure 100 (FIG. It is. FIG. 1 is a side sectional view (FIG. (A)) showing a force sensor according to the present invention in which a capacitive element is incorporated as a detection element in the detection structure shown in FIG. 1 and a bottom view (FIG. (B)) of a lower structure 100. is there. It is a block diagram which shows the basic composition of the force sensor shown in FIG. It is a flowchart which shows the specific process sequence of the comparison means 45 shown in FIG. FIG. 17 is a side sectional view (FIG. (A)) showing a modification of the force sensor shown in FIG. 16 and a bottom view (FIG. (B)) of the lower structure 100. FIG. FIG. 20 is a block diagram showing a basic configuration when auxiliary system signal processing is added to the force sensor shown in FIG. 19. FIG. 6 is a side sectional view (FIG. (A)) of a detection structure used in another embodiment of the force sensor according to the present invention and a bottom view (FIG. (B)) of the lower structure 400. FIG. 22 is a side sectional view showing a deformed state when a force −Fz and a moment + My are applied to the force receiving portion 510 of the detection structure shown in FIG. 21. FIG. 21 is a side sectional view (FIG. (A)) showing a force sensor according to another embodiment of the present invention in which a capacitive element is incorporated as a detection element in the detection structure shown in FIG. 21, and a bottom view of the lower structure 100 (FIG. (b)). FIG. 24 is a side sectional view (FIG. (A)) showing a modified example in which the arrangement pattern of the capacitive element in the force sensor shown in FIG. 23 is changed and a bottom view (FIG. (B)) of the lower structure 100.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

<<< §1. Configuration of a conventional general force sensor >>>
First, in §1, the structure and operation of a conventional general force sensor disclosed in the above-mentioned patent documents and the like will be described for convenience of explanation.

<1-1. Detection structure having a diaphragm portion>
FIG. 1 is a diagram showing an example of a detection structure having a diaphragm portion used in a conventional general force sensor. For example, a structure similar to the structure for detection shown in FIG. 1 is used for the force sensor disclosed in Patent Documents 1 to 3 described above.

  FIG. 1 (a) is a side sectional view of this detection structure. In the case of the illustrated example, the detection structure is constituted by the lower structure 100 and the upper structure 200. FIG. 1B is a top view of the lower structure 100. The lower structure 100 has a structure in which a cylindrical groove H is formed on the lower surface side of the disk, and includes a cylindrical support portion 110 and a circular thin plate-like diaphragm portion 120. The periphery of the diaphragm portion 120 is supported and fixed by the support portion 110, and external force is transmitted to the central portion 125. On the other hand, the upper structure 200 includes a disk-shaped force receiving portion 210 and a columnar force transmitting portion 220. The force transmission part 220 connects the center part of the lower surface of the force receiving part 210 and the center part 125 of the upper surface of the diaphragm part 120.

  The lower structure 100 and the upper structure 200 can be made of a general material such as metal or resin. However, the diaphragm 120 needs to be elastically deformed by the action of an external force, and is therefore a detection target. The thickness is set so as to exhibit flexibility when an external force is applied. The other portions preferably act as rigid bodies as much as possible, and therefore may be made of a material that is sufficiently thicker than the diaphragm portion 120.

  For convenience of explanation, as shown in the figure, the origin O is set at the center of the diaphragm 120, the X axis is in the right direction in FIG. 1 (a), the Z axis is in the upward direction in FIG. 1 (a), and FIG. Taking the Y axis in the upward direction, an XYZ three-dimensional orthogonal coordinate system is defined, and the following operation will be described using the coordinate system. The lower structure 100 shown in FIG. 1 (a) corresponds to a cross-sectional view of the lower structure 100 shown in FIG. 1 (b) cut along the XZ plane.

  After all, when a coordinate system as shown in the figure is defined, the lower structure 100 includes an elastic deformation portion 120 configured by a thin plate-like diaphragm portion extending along the XY plane with the Z axis as a central axis, and the elastic deformation portion. And a support part 110 configured by an annular structure that supports and fixes the periphery of 120, and the upper structure 200 has a Z-axis at a predetermined distance above the elastic deformation part 120. A force receiving portion 210 constituted by a plate-like substrate arranged so as to be the central axis, and a force transmitting portion that connects the lower surface center of the force receiving portion 210 and the upper surface center of the elastic deformation portion 120 along the Z axis. 220.

  In the illustrated example, the diaphragm portion 120 is formed along the XY plane because the diaphragm portion 120 is formed as a remaining upper layer of the lower structure 100 by digging the groove H on the lower surface side of the disk-shaped member. However, the groove H is not necessarily formed on the lower surface side, and may be formed on the upper surface side (in this case, a diaphragm portion is formed as a remaining lower layer). May be formed on both the upper surface side and the lower surface side (in this case, the diaphragm portion is formed as an intermediate remaining layer). In short, the elastically deformable portion 120 may be configured by a thin plate-like diaphragm portion extending along the XY plane or a plane parallel to the XY plane with the Z axis as the central axis.

  In the example shown in the figure, the detection structure is configured by joining the lower structure 100 and the upper structure 200. However, the detection structure has a structure that forms an integral structure as a whole. It doesn't matter. In short, the detection structure used in the force sensor includes an elastic deformation portion 120 that undergoes elastic deformation by the action of force, a support portion 110 that supports the elastic deformation portion 120, and a receiving force that receives an external force to be detected. What is necessary is just to have the part 210 and the force transmission part 220 which transmits the external force applied to this force receiving part 210 to the predetermined location of the elastic deformation part 120.

  Subsequently, a modification mode when an external force is applied to the detection structure shown in FIG. 1 will be described. Here, the deformation | transformation aspect at the time of a specific external force component being added to the force receiving part 210 in the state which fixed the support part 110 is shown. For example, when this detection structure is used as a joint part of a robot arm, the support part 110 is attached to the upper arm part of the robot arm, and the force receiving part 210 is attached to the lower arm part, the lower arm is in a state where the upper arm part is fixed. Due to the external force acting on the part, the elastic deformation part 120 is deformed.

  FIG. 2A is a side sectional view showing a deformation mode of the detection structure when a translational force −Fz (downward force in the figure) in the negative Z-axis direction is applied to the force receiving portion 210. As shown in the figure, the force -Fz is transmitted to the central portion 125 of the elastic deformation portion 120 (diaphragm portion) via the force transmission portion 220, and the elastic deformation portion 120 is elastically deformed so as to protrude downward. On the contrary, when a translational force + Fz (upward force in the figure) in the positive direction of the Z axis is applied, the elastically deforming portion 120 is elastically deformed so as to be convex upward.

  On the other hand, FIG. 2 (b) shows that the force receiving portion 210 has a positive Y-axis moment + My (clockwise moment in the figure: in this application, the rotational direction for advancing the right screw in the positive direction of the predetermined coordinate axis, It is a sectional side view showing a deformation mode of the structure for detection when a positive rotation about the coordinate axis is added. As shown in the figure, the moment + My is transmitted to the central portion 125 of the elastic deformation portion 120 (diaphragm portion) via the force transmission portion 220, and the elastic deformation portion 120 has the right half convex downward and the left half upward as shown. It is elastically deformed to be convex. Conversely, when a negative Y-axis moment -My (counterclockwise moment in the figure) is applied, the elastic deformation portion 120 is elastic so that the right half is convex upward and the left half is convex downward. Deform. The deformation mode when the moment ± Mx around the X axis is applied may be considered as a side sectional view of FIG. 2 (b) cut along the YZ plane.

  As described above, when external forces having various directional components are applied to the force receiving portion 210, the elastic deformation portion 120 is deformed inherently according to the external force, and each portion is bent or displaced. By taking out the bending and displacement of each part thus generated as an electrical signal by the detection element, the applied external force can be detected for each individual direction component.

<1-2. Detection structure with bridge>
FIG. 3 is a diagram illustrating an example of a detection structure having a bridge portion instead of the diaphragm portion. For example, a structure similar to the structure for detection shown in FIG. 3 is used in the force sensor disclosed in Patent Document 4 described above.

  FIG. 3 (a) is a side sectional view of this detection structure. Also in this example, the detection structure is constituted by the lower structure 100 ′ and the upper structure 200. Here, the upper structure 200 shown in FIG. 3A has the same structure as the upper structure 200 used in the detection structure shown in FIG. 1A described in §1-1. It is a member. In contrast, the lower structure 100 ′ shown in FIG. 3A has a slightly different structure from the upper structure 100 shown in FIG.

  FIG. 3B is a top view of the lower structure 100 ′. The lower structure 100 ′ has a support part 110, four bridge parts 121 to 124, and a central part 125. The support portion 110 is a cylindrical component similar to the support portion 110 shown in FIG. 1 and plays a role of supporting and fixing the outer end portions of the four bridge portions 121 to 124. The central portion 125 is a member through which the Z-axis is inserted at the center, similarly to the central portion 115 shown in FIG. 1, and the lower end of the force transmission portion 220 is connected to the upper surface thereof. The four bridge portions 121 to 124 are thin plate members extending radially from the central portion 125 along the XY plane.

  As shown in FIG. 3 (a), a cylindrical groove H is formed inside the cylindrical support portion 110, and the groove H passes through the four fan-shaped openings shown in FIG. 3 (b). Is connected to the upper space of the lower structure 100 '.

  The lower structure 100 ′ and the upper structure 200 can be made of a general material such as metal or resin, but the four bridge portions 121 to 124 need to be elastically deformed by the action of an external force. Therefore, the thickness is set so as to exhibit flexibility when an external force to be detected is applied. The other portions preferably act as rigid bodies as much as possible, and therefore may be made of a sufficiently thick material as compared with the four bridge portions 121 to 124.

  Here, for convenience of explanation, as shown in the drawing, the origin O is set at the center of the central portion 125, the X axis is in the right direction in FIG. 3 (a), the Z axis is in the upward direction in FIG. 3 (a), and FIG. Taking the Y axis in the upward direction, an XYZ three-dimensional orthogonal coordinate system is defined, and the following operation will be described using the coordinate system. The lower structure 100 ′ shown in FIG. 3 (a) corresponds to a cross-sectional view of the lower structure 100 ′ shown in FIG. 3 (b) cut along the XZ plane.

  After all, the detection structure shown in FIG. 3 can be said to be obtained by replacing the elastic deformation portion 120 (diaphragm portion) of the detection structure shown in FIG. 1 with four bridge portions 121 to 124. The bridge portions 121 to 124 and the central portion 125 function as the elastic deformation portion 120. In the case of the illustrated example, the four bridge portions 121 to 124 are arranged at positions on the XY plane, but of course, the positions of the four bridge portions 121 to 124 are limited to positions extending along the XY plane. However, it may be arranged at a position extending along another plane parallel to the XY plane. In the illustrated example, four bridge portions 121 to 124 are provided. However, the number of bridge portions is not limited to four, and any number of bridge portions may be used as long as there are a plurality of bridge portions. The material of each part may be the same as that of the detection structure shown in FIG.

  As described above, the characteristic of the detection structure described in §1-2 is constituted by the lower structure 100 ′ and the upper structure 200, and the lower structure 100 ′ is an elastic structure composed of a plurality of bridge portions. It is a point provided with the deformation | transformation part and the support part 110 comprised by the cyclic | annular structure which supports and fixes the circumference | surroundings of this elastic deformation part. More specifically, the elastically deforming portion includes a central portion 125 located on the Z axis and a plurality of thin plate-like bridge portions extending radially from the central portion 125 along a plane parallel to the XY plane or the XY plane. (In this example, four bridge portions 121 to 124).

  On the other hand, the upper structure 200 includes a force receiving portion 210 configured by a plate-like substrate disposed so that the Z axis is a central axis at a predetermined distance above the elastic deformation portions (121 to 125), And a force transmission unit 220 that connects the center of the lower surface of the force receiving unit 210 and the upper surface of the central part 125 of the elastically deforming unit along the Z-axis.

  In particular, in the case of the detection structure illustrated in FIG. 3B, the elastically deforming portion includes a thin plate-like first bridge portion 121 extending from the central portion 125 toward the X-axis positive direction, and the central portion 125 extending from the X-axis. A thin plate-like second bridge portion 122 extending toward the negative direction, a thin plate-like third bridge portion 123 extending from the central portion 125 toward the Y-axis positive direction, and a central portion 125 extending toward the Y-axis negative direction. And a fourth bridge portion 124 having a thin plate shape. For this reason, the structure is suitable when a specific arrangement of detection elements as described later is employed.

  Thus, in the example shown in FIG. 1, the elastic deformation portion is configured by the diaphragm portion 120, whereas in the example shown in FIG. 3, the elastic deformation portion is configured by a plurality of bridge portions 121 to 124. Yes. The diaphragm portion 120 and the plurality of bridge portions 121 to 124 are the same in that they are bent by the action of an external force, and the elastic deformation portion for the detection structure may be constituted by a diaphragm portion, or a plurality of bridge portions 121 to 124 may be formed. You may comprise by the bridge part.

  In this application, for the sake of convenience, in the following description, an example in which the elastic deformation portion for the detection structure is configured by a diaphragm portion will be shown as a representative example, but the diaphragm portion in these examples may include a plurality of bridges as appropriate. It is possible to replace it with a part.

  In addition, since the deformation | transformation aspect when an external force acts on the structure for a detection shown in FIG. 3 is the same as the deformation | transformation aspect shown in FIG. 2, description is abbreviate | omitted here.

<1-3. Example using piezoresistive element>
FIG. 4 is a view showing a conventional force sensor in which a piezoresistive element is incorporated as a detection element in the detection structure shown in FIG. FIG. 4 (a) is a side sectional view showing a state in which the force sensor is cut along the XZ plane, and FIG. 4 (b) is a top view of the lower structure 100 of the force sensor.

  As shown in FIG. 4B, in this example, four sets of piezoresistive elements R1 to R4 (indicated by small black rectangles) are arranged on the upper surface of the elastic deformation portion 120 (diaphragm portion). Specifically, the resistance elements R1 and R2 are disposed at positions along the X axis, and the resistance elements R3 and R4 are disposed at positions along the Y axis. As shown in the side sectional view of FIG. 4A, each of the resistance elements R1 to R4 is embedded in the upper surface of the elastic deformation portion 120. Therefore, when the elastic deformation portion 120 is deformed by the action of an external force, It is possible to detect a deflection occurring at each position on the upper surface as a change in electrical resistance.

  Here, for convenience of explanation, detection points P11 to P14 are defined at respective positions on the upper surface of the elastic deformation portion 120, as indicated by x in FIG. The four sets of resistance elements R1 to R4 are disposed at the positions of the detection points P11 to P14, respectively, and can detect the deflection generated at the positions of the detection points P11 to P14 as changes in electrical resistance. In the case of the illustrated example, the resistance element R1 is arranged at the position of the detection point P11 so that the longitudinal direction thereof faces the X-axis direction, and the resistance element R2 is arranged at the position of the detection point P12 so that the longitudinal direction thereof faces the X-axis direction. The resistive element R3 is arranged at the position of the detection point P13 so that the longitudinal direction thereof faces the Y-axis direction, and the resistive element R4 is arranged at the position of the detection point P14 so that the longitudinal direction thereof faces the Y-axis direction.

  FIG. 5 is a side sectional view showing the principle of detection of force -Fz and moment + My by the force sensor shown in FIG. In the case of this force sensor, as shown in FIG. 5 (a), when a downward force -Fz is applied to the force receiving portion 210, the elastic deformation portion 120 is elastically deformed so as to protrude downward. At this time, stress that contracts in the X-axis direction is applied to the detection points P11 and P12 located on the upper surface of the elastic deformation portion 120, as indicated by white arrows in the figure. Similarly, stress that contracts in the Y-axis direction is applied to the detection points P13 and P14 located on the upper surface of the elastic deformation portion 120. For this reason, the resistance values of the four sets of resistance elements R1 to R4 decrease. On the other hand, when an upward force + Fz is applied, the elastic deformation part 120 is elastically deformed so as to be convex upward, so that the detection points P11 to P14 located on the upper surface of the elastic deformation part 120 may have X axis Stress that extends in the axial direction is applied, and the resistance values of the four sets of resistance elements R1 to R4 increase.

  On the other hand, when a moment + My about the Y-axis is applied to the force receiving portion 210, the elastic deformation portion 120 has a right half convex downward and a left half convex upward as shown in FIG. 5 (b). Since it is elastically deformed, as shown by the white arrow in the figure, stress that contracts in the X-axis direction is applied to the detection point P11, and stress that extends in the X-axis direction is applied to the detection point P12. For this reason, the resistance value of the resistance element R1 decreases and the resistance value of the resistance element R2 increases. At this time, no significant change occurs in the resistance values of the resistance elements R3 and R4.

  The manner in which the resistance value increases or decreases when the moment -My around the negative Y-axis is applied is the reverse of the above. Further, when a moment ± Mx about the X axis is applied, the resistance values of the resistance elements R3 and R4 increase and decrease, and no significant change occurs in the resistance values of the resistance elements R1 and R2. The operation is as described above when the detection points P11 to P14 are defined on the upper surface of the elastic deformation portion 120. The detection points are defined on the lower surface of the elastic deformation portion 120, and each piezoresistive element is connected to the lower surface of the elastic deformation portion 120. Since the expansion and contraction forms are reversed, the increase and decrease of the resistance elements are also reversed. If the increase / decrease of each resistance element is electrically detected, the applied external force can be detected for each direction component.

<1-4. Example using capacitive element>
FIG. 6 is a diagram showing a conventional force sensor in which a capacitive element is incorporated as a detection element in the detection structure shown in FIG. FIG. 6A is a side sectional view showing a state where the force sensor is cut along the XZ plane, and FIG. 6B is a bottom view of the lower structure 100 of the force sensor. 1 (b) and 4 (b) are top views, while FIG. 6 (b) is a bottom view of the lower structure 100 as viewed from below. Is reversed.

  In the example shown here, as shown in FIG. 6 (b), detection points P21 to P24 are defined at respective positions on the lower surface of the elastic deformation portion 120 (diaphragm portion), and the displacements of these detection points P21 to P24 are defined. 4 sets of capacitive elements C1 to C4 are provided. That is, as shown in FIG. 6 (b), small disc-shaped displacement electrodes E21 to E24 are fixed on the lower surface of the elastic deformation portion 120 at the positions of the detection points P21 to P24, respectively. Specifically, the displacement electrodes E21 and E22 are disposed at positions along the X axis, and the displacement electrodes E23 and E24 are disposed at positions along the Y axis.

  On the other hand, as shown in FIG. 6 (a), a disk-shaped electrode support substrate 300 is disposed inside the cylindrical support portion 110, and four fixed electrodes are disposed on the upper surface of the electrode support substrate 300. E11 to E14 are arranged. The electrode support substrate 300 is a component for supporting the fixed electrodes E <b> 11 to E <b> 14, and the outer peripheral surface thereof is connected to the inner peripheral surface of the support part 110. The fixed electrodes E11 to E14 are disk-shaped electrodes having the same size as the displacement electrodes E21 to E24, and are disposed at positions facing the displacement electrodes E21 to E24, respectively. That is, the planar arrangement of the fixed electrodes E11 to E14 is the same as the planar arrangement of the displacement electrodes E21 to E24 shown in FIG.

  Thus, the four displacement electrodes E21 to E24 and the four fixed electrodes E11 to E14 facing the displacement electrodes E21 to E24 constitute a total of four capacitive elements C1 to C4. That is, the capacitive element C1 is configured by the displacement electrode E21 and the fixed electrode E11, and is used to detect the displacement of the detection point P21. The capacitive element C2 is configured by the displacement electrode E22 and the fixed electrode E12, and the detection point P22. The capacitive element C3 is composed of the displacement electrode E23 and the fixed electrode E13, and is used to detect the displacement of the detection point P23. The capacitive element C4 is used for detecting the displacement of the displacement electrode E24 and the fixed electrode E14. And is used to detect the displacement of the detection point P24. In the drawing, the reference numerals of the capacitive elements C1 to C4 are shown in parentheses near the reference numerals of the displacement electrodes E21 to E24.

  For convenience of illustration, FIG. 6A shows that there is not much difference between the thickness of the diaphragm portion 120 and the thickness of the electrode support substrate 300, but in actuality, the diaphragm portion 120 functions as an elastic deformation portion. The electrode support substrate 300 is sufficiently thin to function as a rigid body. Accordingly, the displacement electrodes E21 to E24 are displaced according to the deformation of the diaphragm portion 120, but the fixed electrodes E11 to E14 are not displaced because the electrode support substrate 300 is not deformed. For this reason, when an external force acts and the diaphragm part 120 bends, each detection point P21-P24 produces a displacement, The said displacement is electrically detected as a change of the electrostatic capacitance value of each capacitive element C1-C4. Can do.

  FIG. 7 is a side sectional view showing the principle of detection of force -Fz and moment + My by the force sensor shown in FIG. In the case of this force sensor, as shown in FIG. 7 (a), when a downward force -Fz is applied to the force receiving portion 210, the elastic deformation portion 120 is elastically deformed so as to protrude downward. At this time, since the detection points P21 and P22 located on the lower surface of the elastic deformation portion 120 are displaced downward in the figure, the distance between the electrodes of the capacitive elements C1 and C2 arranged at the positions of the detection points P21 and P22 is It decreases and the capacitance value increases. Since the detection points P23 and P24 are similarly displaced downward, the distance between the electrodes of the capacitive elements C3 and C4 also decreases, and the capacitance value increases. That is, due to the downward force -Fz, the distance between the electrodes of all the capacitive elements C1 to C4 decreases, and the capacitance value increases. Conversely, when an upward force + Fz is applied, the distance between the electrodes of all the capacitive elements C1 to C4 increases, and the capacitance value decreases.

  On the other hand, when a moment + My about the Y-axis is applied to the force receiving portion 210, the elastic deformation portion 120 has a right half projecting downward and a left half projecting upward as shown in FIG. 7B. Due to elastic deformation, the distance between the electrodes of the capacitive element C1 decreases and the capacitance value increases, but the distance between the electrodes of the capacitive element C2 increases and the capacitance value decreases. At this time, the distance between the electrodes of the capacitive elements C3 and C4 increases in part, but decreases in the other part, so that there is no significant change in the capacitance value.

  The manner in which the capacitance value increases or decreases when the moment -My around the negative Y-axis is applied is the reverse of the above. Further, when a moment ± Mx about the X axis is applied, the capacitance values of the capacitive elements C3 and C4 increase and decrease, and no significant change occurs in the capacitance values of the capacitive elements C1 and C2. If the increase / decrease of each capacitive element is electrically detected, the applied external force can be detected for each direction component.

<1-5. Signal processing>
Up to now, the configuration of a conventional force sensor using a piezoresistive element is illustrated in §1-3, and the configuration of a conventional force sensor using a capacitive element is illustrated in §1-4. Here, for these force sensors, detection values indicating the force component Fz in the Z-axis direction of the external force applied to the force receiving portion 210, the moment component Mx around the X axis, and the moment component My around the Y axis are output. The signal processing for this will be briefly described.

  FIG. 8 is a table showing changes in resistance values of the piezoresistive elements R1 to R4 when three types of external force components Fz, Mx, and My act on the force sensor shown in FIG. 4 described in §1-3. It is a figure which shows the computing equation which calculates | requires the predetermined direction component of the applied external force. In the upper table, “+” indicates an increase in resistance value, “−” indicates a decrease in resistance value, and “0” indicates that no significant change occurs in the resistance value. As described above in §1-3, such a resistance value change occurs in each of the resistance elements R1 to R4.

Therefore, when the resistance values of the respective resistance elements R1 to R4 are expressed as R1 to R4 using the same reference numerals, the arithmetic expression shown in the lower stage:
Fz = K1 × (R1 + R2 + R3 + R4)
Mx = K2 × (R3-R4)
My = K3 × (R2-R1)
By performing the calculation based on, three types of external force components Fz, Mx, and My can be calculated. Here, K1, K2, and K3 are predetermined proportional coefficients, and become scaling factors for outputting Fz, Mx, and My as accurate force detection values. In addition, when the electrical characteristics of the piezoresistive element used are different from the above example (for example, when the resistance value increases with respect to shrinking stress and the resistance value decreases with respect to expanding stress), If necessary, the proportionality coefficients K1, K2, and K3 may have negative values.

  Note that the zero value of the detection value Fz calculated by the arithmetic expression shown in the figure is not set correctly, so that the zero value correction is actually performed so that the calculation value Fz when no external force is applied is output as the detection value 0. Need to do. Since the detected values Mx and My are differential calculation values, the calculated values Mx and My when no external force is applied should theoretically be zero.

  Further, in practice, instead of performing the above arithmetic processing, it is also possible to perform signal processing corresponding to the arithmetic processing. For example, since the values of Mx and My are given as differential calculation values, it is possible to configure a bridge circuit using each resistance element and output an analog signal corresponding to the differential calculation value as the bridge voltage of the bridge circuit. It is. Since such a specific signal processing technique is already a known technique, a description thereof is omitted here.

  On the other hand, FIG. 9 shows changes in the capacitance values of the capacitive elements C1 to C4 when three types of external force components Fz, Mx, and My act on the force sensor shown in FIG. 6 described in §1-4. FIG. 6 is a diagram showing a calculation formula for obtaining a predetermined direction component of an applied external force and a table showing the above. In the upper table, “+” indicates an increase in capacitance value, “−” indicates a decrease in capacitance value, and “0” indicates that no significant change occurs in the capacitance value. Yes. Such a change in resistance value occurs in each of the capacitive elements C1 to C4, as already described in §1-4.

Therefore, if the capacitance values of the capacitive elements C1 to C4 are expressed as C1 to C4 using the same symbols, respectively, the arithmetic expression shown in the lower stage:
Fz = −K1 × (C1 + C2 + C3 + C4)
Mx = K2 × (C4-C3)
My = K3 × (C1-C2)
By performing the calculation based on, three types of external force components Fz, Mx, and My can be calculated. Here, K1, K2, and K3 are predetermined proportional coefficients, and become scaling factors for outputting Fz, Mx, and My as accurate force detection values.

  Note that the detected value Fz calculated by the illustrated arithmetic expression is not set to the zero point correctly, so that the zero value correction is actually performed so that the calculated value Fz when no external force is applied is output as the detected value 0. Need to do. Since the detected values Mx and My are differential calculation values, the calculated values Mx and My when no external force is applied should theoretically be zero.

  In practice, in order to take out the capacitance values C1 to C4 of the capacitive elements C1 to C4 as electric signals, it is necessary to use a C / V conversion circuit or the like. Is well known, and the description is omitted here.

  After all, in the case of the force sensor shown in FIG. 4 described in §1-3, since the piezoresistive elements R1 to R4 are used as the detection elements, the arithmetic processing based on the arithmetic expression shown in the lower part of FIG. It is necessary to prepare means for performing signal processing corresponding to the arithmetic processing. In the case of the force sensor shown in FIG. 6 described in §1-4, the capacitive elements C1 to C4 are used as the detection elements. Therefore, it is necessary to prepare means for performing arithmetic processing based on the arithmetic expression shown in the lower part of FIG. 9 or signal processing corresponding to the arithmetic processing.

  FIG. 10 is a top view showing the arrangement of the detection elements D1 to D4 with respect to the diaphragm portion 120 in the force sensor shown in FIGS. 4 and 6. In the case of the force sensor shown in FIG. 4, the detection elements D1 to D4 are piezoresistive elements R1 to R4 embedded in the upper surface of the diaphragm 120. In the case of the force sensor shown in FIG. ˜D4 are capacitive elements C1 to C4 configured by a displacement electrode fixed to the lower surface of the diaphragm 120 and a fixed electrode facing the displacement electrode. FIG. 10 shows elements such as piezoresistive elements and capacitive elements as detection elements D1 to D4 as general concepts, and four sets of squares denoted by reference signs D1 to D4 in the figure are such general The arrangement | positioning of the detection elements D1-D4 as a concept is shown.

  Here, the first detection element D1 is an element that electrically detects the bending or displacement of the first detection point P1, and the second detection element D2 is the bending or displacement of the second detection point P2. The third detection element D3 is an element that electrically detects deflection or displacement of the third detection point P3, and the fourth detection element D4 is the fourth detection element D4. This is an element for electrically detecting the deflection or displacement of the second detection point P4.

  When the detection elements D1 to D4 are grasped as general elements having a function of electrically detecting the deflection or displacement of the detection points P1 to P4 as in the example shown in FIG. An arithmetic expression for obtaining the predetermined direction component can be expressed by a general expression as shown in FIG. In this equation, variables Fz, Mx, My are detected values indicating the force component Fz in the Z-axis direction of the external force applied to the force receiving portion 210, the moment component Mx around the X axis, and the moment component My around the Y axis. Yes, variables D1 to D4 are values of detection signals obtained from the detection elements D1 to D4 shown in FIG. 10, and K1, K2, and K3 are predetermined signed proportional coefficients.

  Here, the signs of the proportional coefficients K1, K2, and K3 indicate what detection element is actually used as each of the detection elements D1 to D4 (for example, a piezoresistive element or a capacitive element), and indicates each detection element D1 to D4. It is determined depending on circumstances such as where to place (for example, the upper surface or the lower surface of the diaphragm portion). For example, in the case of the force sensor shown in FIG. 4 described in §1-3, the arithmetic expression shown in the lower part of FIG. 8 is actually used. The arithmetic expression is the general expression shown in FIG. In the equation, the variables D1 to D4 are replaced with the resistance values R1 to R4, and the equation is nothing but the proportionality coefficient K3 is set to a negative value. Similarly, in the case of the force sensor shown in FIG. 6 described in §1-4, the arithmetic expression shown in the lower part of FIG. 9 is actually used, but the arithmetic expression is shown in FIG. In the general formula, the variables D1 to D4 are replaced with the capacitance values C1 to C4 and the proportional coefficients K1 and K2 are set to negative values.

  Thus, if K1, K2, and K3 are handled as signed proportional coefficients, the general formula of FIG. 11 can be applied to any case. Accordingly, in each of the following embodiments, description will be made using the general formula of FIG. 11. However, in the proportional coefficients K1, K2, and K3, appropriate codes are set for the respective embodiments. It shall be.

<<< §2. Basic embodiment of the present invention >>
Subsequently, in §2, a basic embodiment of the force sensor according to the present invention will be described.

<2-1. Basic concept of the present invention>
First, the basic concept of the present invention will be described along with the problems of the conventional force sensor. FIG. 12 is a block diagram showing a difference in basic configuration between a conventional force sensor and the force sensor according to the present invention.

  FIG. 12 (a) shows a basic configuration of the conventional force sensor described in §1 as a block diagram. As shown in the figure, this force sensor has a detection structure 10, a detection element 20, and a signal processing means 30. The detection structure 10 is a mechanical structure illustrated in FIGS. 1 and 3 and includes an elastic deformation portion that generates elastic deformation by the action of a force. As already described, when an external force to be detected acts on the detection structure 10, the elastic deformation portion is deformed.

  A plurality of detection points are defined in the elastic deformation part in the detection structure 10, and the detection element 20 has a function of detecting deformation near each detection point as an electric signal. In §1, an example in which a piezoresistive element that detects deflection near each detection point as an electrical signal is used as the detection element 20 or a capacitance element that detects displacement in the vicinity of each detection point as an electrical signal is described. It was.

  The detection signal obtained by each detection element 20 is given to the signal processing means 30. The signal processing means 30 has a function of obtaining a detection value indicating a predetermined direction component of the external force applied to the detection structure 10 based on an electrical detection signal from each element, and outputting this as a final detection value. Have. FIG. 11 shows an arithmetic expression for calculating detection values of three types of external force components Fz, Mx, and My based on detection signal values D1 to D4 obtained from four sets of detection elements D1 to D4. . The signal processing means 30 has a function of calculating external force components Fz, Mx, My, and the like based on such an arithmetic expression and outputting them as final detection values.

  However, as described above, the conventional force sensor having such a configuration has a problem that abnormality occurs due to various factors. For example, since the detection structure is a physical structure, if each part is mechanically damaged, it will not function normally. Similarly, the detection element 20 is a part including delicate parts such as a piezoresistive element and a capacitive element, and is easily damaged. For example, in the case of a capacitive element, if impurities enter between the electrodes, it will not operate normally. Further, the wiring of the signal line is indispensable between the detection element 20 and the signal processing means 30, but if this signal line is disconnected, a normal detection signal cannot be obtained. Of course, malfunction may occur in the electronic circuit constituting the signal processing means 30.

  As described above, when an abnormality occurs in a force sensor used in a life support robot or a medical support robot, the robot malfunctions, and there is a possibility of harming a person. In particular, if the control of the medical support robot breaks down and causes runaway, there is a possibility that it may lead to a serious matter related to human life.

  In general, as a method to ensure system safety, fault detection (fault tolerance) is to provide redundancy by multiplexing detection systems and control systems, and to maintain normal functions in the other even if an abnormality occurs. The idea of this is prevalent.

  In view of such a way of thinking, it is possible to configure a force sensor as shown in FIG. The force sensor shown in FIG. 12 (b) is configured by further adding a comparing means 40 to the two force sensors shown in FIG. 12 (a). That is, the first sensor SA surrounded by the dashed line in the upper part of the figure and the second sensor SB enclosed by the dashed line in the lower part of the figure are both the same as the force sensor shown in FIG. It is. The external force to be detected is applied to the detection structure 10A of the first sensor SA and also to the detection structure 10B of the second sensor SB. The first sensor SA and the second sensor SB are separate and independent sensors and output independent detection values.

  Specifically, in the first sensor SA, the deformation generated in the vicinity of each detection point of the detection structure 10A based on the external force is detected by the detection element 20A, and the obtained detection signal is processed by the signal processing means 30A. As a result, the detection value VA of the first sensor is output. Similarly, in the second sensor SB, the deformation generated in the vicinity of each detection point of the detection structure 10B based on the same external force is detected by the detection element 20B, and the obtained detection signal is processed by the signal processing means 30B. As a result, the detection value VB of the second sensor is output.

  Thus, when two independent detection values VA and VB are obtained, the comparison means 40 compares them, and if the difference between the two is within a predetermined allowable range, either one of the detection values or the average value of the two is obtained. Etc. may be output as the final detection value. If the difference between the two exceeds a predetermined allowable range, some error output is performed. Then, as long as there is no error output, approximate detection values are obtained in both the sensors SA and SB, and the final detection value can be treated as a reliable value for the time being. In the unlikely event that an error is output, the control system of the robot can avoid harming humans by taking emergency measures such as emergency stop of the driving of the robot.

  However, since the force sensor shown in FIG. 12B includes two sets of independent sensors, it is inevitable that the entire apparatus becomes large and the manufacturing cost increases. In the block diagram of FIG. 12 (b), the same external force is applied to each of the two sets of detection structures 10A, 10B. Since 10A and 10B are separate and independent physical structures, the external forces that are the detection targets of both sensors SA and SB are not the same even if they are arranged adjacent to each other. For this reason, an error is potentially included between the two independent detection values VA and VB.

  Therefore, the force sensor according to the present invention employs a basic configuration as shown in the block diagram of FIG. The force sensor is characterized in that the detection structure is constituted by a single structure as in the example shown in FIG. 12 (a), while the detection element and signal processing means are shown in FIG. 12 (b). As in the example shown in FIG. 4, two sets are provided to ensure redundancy.

  That is, the external force to be detected is applied to the single detection structure 10, but the deformations that occur in the vicinity of each detection point of this detection structure 10 are the A system detection element 25 </ b> A and the B system detection element 25 </ b> B. And detected respectively. Actually, a plurality of n detection points are defined in the detection structure 10, and n A system detection elements 25A and n B detection points are detected in order to detect deflection or displacement in the vicinity of the n detection points. A system detection element 25B is provided. The detection signals from the n A system detection elements 25A are processed by the A system signal processing means 35A and output as the A system detection value A, and the detection signals from the n B system detection elements 25B are B It is processed by the system signal processing means 35B and output as the B system detection value B.

  In this way, when two independent detection values A and B are obtained, the comparison means 45 compares them, and if the difference between the two is within a predetermined allowable range, either one of the detection values or the average value of the two is obtained. Etc. may be output as the final detection value. If the difference between the two exceeds a predetermined allowable range, some error output is performed. By doing so, unless there is an error output, approximate detection values are obtained in both the A system and the B system, and the final detection values can be treated as reliable values. In the unlikely event that an error is output, the control system of the robot can avoid harming humans by taking emergency measures such as emergency stop of the driving of the robot.

  In this way, in the force sensor according to the present invention shown in FIG. 12 (c), the two types of A system detection value A and B system detection value B are obtained by passing through two systems of A system and B system. Since the detection value can be obtained, the comparison means 45 compares the two to output an error when the difference between the two exceeds a predetermined allowable value, indicating that some abnormality has occurred to the outside. Can be notified.

  Moreover, since the detection structure 10 is composed of a single structure, the overall size of the apparatus is substantially the same as that of the force sensor shown in FIG. It is necessary to prepare two systems for the detection element and the signal processing means, but the manufacturing process is not significantly different for one system or two systems, and the manufacturing cost is also the manufacturing cost of the force sensor shown in FIG. Can be suppressed to a level slightly above. Of course, since the structure 10 for detection is single, the A system detection value A and the B system detection value B are detection values for the same external force as detection targets.

  As a result, the force sensor according to the present invention includes a detection structure 10, n A system detection elements 25A, n B system detection elements 25B, as shown in a block diagram in FIG. A system signal processing means 35A, B system signal processing means 35B, and comparison means 45 are provided, and a predetermined direction component of external force acting on the detection structure 10 is output as a final detection value. When it is recognized that an abnormality has occurred, it has a function of outputting an error and notifying the outside.

  Here, in the same way as the detection structure used in the conventional force sensor described in §1, the detection structure 10 includes an elastic deformation portion 120 that generates elastic deformation by the action of force, and the elastic deformation. A support portion 110 that supports the portion 120, a force receiving portion 210 that receives an external force to be detected, a force transmission portion 220 that transmits the external force applied to the force receiving portion 210 to a predetermined location of the elastic deformation portion 120, have. A plurality of n detection points are defined at predetermined positions of the elastic deformation portion 120.

  The n A-line detection elements 25A are detection elements that electrically detect bending or displacement generated in the first vicinity of the plurality of n detection points, and the n B-line detection elements 25B are A detection element that electrically detects the bending or displacement of the plurality of n detection points generated in a second neighboring portion different from the first neighboring portion.

  Here, paying attention to an arbitrary i (1 ≦ i ≦ n), the i-th A system detection element electrically detects the deflection or displacement of the first vicinity of the i-th detection point, The i-th B system detection element plays a role of electrically detecting deflection or displacement of the second vicinity of the i-th detection point. For example, the first A-line detection element electrically detects the deflection or displacement of the first vicinity of the first detection point, and the first B-line detection element detects the first detection point. The deflection or displacement of the second vicinity of the point is electrically detected.

  On the other hand, the A system signal processing means 35A is based on the electrical detection signals detected by the n A system detection elements 25A and indicates the A system detection value indicating the predetermined direction component of the external force applied to the force receiving section 210. A is output. Similarly, the B system signal processing unit 35B detects the B system detection indicating the predetermined direction component of the external force applied to the force receiving unit 210 based on the electrical detection signals detected by the n B system detection elements 25B. Outputs value B.

  And the comparison means 45 compares A system detection value A and B system detection value B, calculates | requires the difference d of both, and was calculated based on A system detection value A or B system detection value B, or these both A predetermined calculation value (for example, an average value of both) is output as a final detection value, and when the difference d exceeds a predetermined allowable value T, a difference error is output.

  This difference error indicates that a wrinkle exceeding a predetermined allowable value T has occurred between the A system detection value A and the B system detection value B, and some abnormality has occurred in the force sensor. It becomes the signal which shows that. As described above, since the force sensor according to the present invention has a function of notifying the outside as a difference error when the above abnormality occurs, when the sensor is incorporated in a robot or the like, the robot control is performed. It is possible to cause the apparatus to recognize the occurrence of an abnormality, and to prevent humans from being harmed due to a malfunction of the robot.

  When the configuration of the present invention shown in FIG. 12C is compared with the configuration shown in FIG. 12B, a measure for providing redundancy to the detection structure 10 is omitted. If a mechanical damage occurs, a correct detection value cannot be output. However, in general, the durability of the detection structure 10 is higher than the durability of the detection element 20 and the signal processing means 30, and therefore, as shown in FIG. Even if a measure for providing redundancy is taken, the reliability of the force sensor can be sufficiently improved.

  As will be described later in the embodiment, the comparison means 45 may have a function of selectively outputting a more appropriate one (higher reliability) of the A system detection value A and the B system detection value B. Is possible. Therefore, as shown in FIG. 12 (c), if the detection element and the signal processing means are provided with redundancy so that the A system and the B system are made independent independently, a failure occurs in one system. However, the detection value of the other system can be output as the final detection value, and the reliability can be improved.

  In particular, detection elements are prone to failure due to disconnection of signal lines or contamination of foreign objects due to use in the actual environment. For example, when capacitive elements are used, damage to wiring to each electrode or between opposing electrodes If impurities are mixed in, normal operation cannot be achieved. Further, when used in a high humidity environment, the capacitance value greatly fluctuates due to condensation or slight water immersion, so that the output capacitance value does not correspond to the correct inter-electrode distance. In the force sensor according to the present invention, the detection element and the signal processing means are multiplexed. Therefore, even if a failure occurs in one system, the detection value of the other system is finalized. Reliability can be improved by outputting as a detection value.

<2-2. Specific Detection Element Arrangement and Signal Processing>
Next, a specific arrangement example of the detection elements in the force sensor according to the present invention and a specific signal processing method for the detection signals obtained from the detection elements will be described.

  In §1 described above, the arrangement of the detection elements D1 to D4 in the conventional general force sensor with respect to the diaphragm 120 is described with reference to FIG. FIG. 13 is a top view showing an arrangement example of the detection elements D1A to D4A and D1B to D4B in the force sensor according to the present invention in comparison with the conventional example shown in FIG.

  In the case of the conventional example shown in FIG. 10, four detection points P1 to P4 are defined at predetermined positions of the diaphragm portion 120, and in order to detect bending or displacement of the diaphragm portion 120 at the positions of the detection points P1 to P4, Four sets of detection elements D1 to D4 (actually, piezoresistive elements R1 to R4 and capacitive elements C1 to C4) are arranged. As described above, the four sets of squares denoted by reference numerals D1 to D4 in the drawing indicate the arrangement of the detection elements D1 to D4 as a general concept.

  On the other hand, in the example according to the present invention shown in FIG. 13, the four detection points P <b> 1 to P <b> 4 are defined at predetermined positions of the diaphragm unit 120, but four sets of detection elements D <b> 1. 8 sets of detection elements D1A to D4A and D1B to D4B are arranged instead of to D4. Again, the eight sets of rectangles labeled D1A to D4A and D1B to D4B in the figure indicate the arrangement of the detection elements D1A to D4A and D1B to D4B as a general concept using graphic symbols. It does not show the actual physical shape. Actually, these eight sets of detection elements D1A to D4A and D1B to D4B are configured by piezoresistive elements and capacitive elements having a predetermined shape.

  In the example shown in FIG. 13, a detection reference plane is defined on the XY plane (or an arbitrary plane parallel to the XY plane), and a detection reference circle G1 (centered on the Z axis) is formed on the detection reference plane. In the drawing, the four detection points P1 to P4 are all located on the detection reference circle G1. In other words, the four detection points P1 to P4 are all arranged at positions equidistant from the Z axis.

  Of course, in implementing the present invention, the n detection points may be defined at arbitrary positions, but in practice, as shown in the figure, all the n detection points are equidistant from the Z axis. In other words, when the detection reference plane is defined on the XY plane or a plane parallel to the XY plane and the detection reference circle G1 centered on the Z axis is drawn on this detection reference plane It is preferable that all the n detection points are arranged on the detection reference circle G1. This is because by adopting such a symmetrical arrangement, the value of the detection signal obtained from each detection element is also symmetrical, and signal processing (arithmetic processing) by the signal processing means is performed. This is because it can be simplified.

  For the detection points P1 to P4, when the side far from the Z axis is referred to as the outside, and the side close to the Z axis is referred to as the inside, among the eight sets of detection elements shown in FIG. The four detection elements D1A to D4A that are attached are arranged outside the detection points P1 to P4, and the four sets of detection elements D1B to D4B that are suffixed with B are the detection points P1 to P4. It can be seen that it is arranged inside P4. Here, the four sets of detection elements D1A to D4A arranged on the outside correspond to the A system detection elements shown in FIG. 12C, and the four sets of detection elements D1B to D4B arranged on the inside are: This corresponds to the B system detection element shown in FIG.

  The first A-system detection element D1A electrically detects the deflection or displacement of the vicinity of the outside of the first detection point P1, and the first B-system detection element D1B is the first detection. The bending or displacement of the portion near the inside of the point P1 is electrically detected.

  In the case of the conventional example shown in FIG. 10, the detection element D1 is the only element that detects the deflection or displacement of the position of the detection point P1, so the detection element D1 can be arranged immediately above the detection point P1. It is. On the other hand, in the case of the example according to the present invention shown in FIG. 13, it is necessary to provide the A system detection element D1A and the B system detection element D1B as elements that detect the deflection or displacement of the position of the detection point P1. There is. Therefore, in the case of the embodiment shown in FIG. 13, the A system detection element D1A is slightly deviated from the detection point P1, but it is arranged in the vicinity of the outside thereof, and the B system detection element D1B is slightly deviated from the detection point P1. Although it comes off, the arrangement method of arranging in the position near the inside is adopted.

  Therefore, both the A system detection element D1A and the B system detection element D1B function as elements that electrically detect deflection or displacement in the vicinity of the detection point P1, but strictly speaking, the A system detection element Since the element D1A detects the portion near the outside of the detection point P1, and the B system detection element D1B detects the portion near the inside of the detection point P1, the values of the detection signals obtained from both do not completely match.

  Similarly, the second A-system detection element D2A electrically detects the deflection or displacement of the vicinity near the outside of the second detection point P2, and the second B-system detection element D2B The bending or displacement of the vicinity portion inside the second detection point P2 is electrically detected. The third A-system detection element D3A electrically detects the deflection or displacement of the vicinity of the outside of the third detection point P3, and the third B-system detection element D3B is the third The deflection or displacement of the vicinity inside the detection point P3 is electrically detected. And the 4th A system detection element D4A electrically detects the bending or displacement of the vicinity part outside the 4th detection point P4, and the 4th B system detection element D4B is the 4th The deflection or displacement of the vicinity inside the detection point P4 is electrically detected.

  In FIG. 13, by setting n = 4, four detection points P1 to P4 are defined, and four sets of A system detection elements D1A to D4A are arranged outside the detection points P1 to P4. Although an example in which four sets of B-system detection elements D1B to D4B are arranged inside each detection point P1 to P4 is shown as a general theory, when a plurality of n detection points are defined, any i (1 ≦ 1 For i ≦ n), the i-th A-system detection element DiA electrically detects the deflection or displacement of the vicinity of the outside of the i-th detection point Pi, and the i-th B-system detection element DiB is The bending or displacement of the vicinity of the inside of the i-th detection point Pi may be detected electrically. To do so, the i-th A-system detection element DiA is arranged outside the i-th detection point Pi, and the i-th B-system detection element DiB is placed inside the i-th detection point Pi. What is necessary is just to arrange.

  Here, the detection elements D1A, D1B, D2B, and D2A arranged on the X axis are piezoresistive elements extending in the X axis direction, and the detection elements D3A, D3B, D4B, and D4A arranged on the Y axis are Assuming that the piezoresistive elements extend in the Y-axis direction, a table showing changes in detection signals obtained from the detection elements D1A to D4A and D1B to D4B is shown in FIGS. 14 (a) and 14 (b). become.

  FIG. 14 (a) shows changes in the resistance values of the A system detection elements D1A to D4A when three types of external force components Fz, Mx, and My act, and FIG. 14 (b) shows each B system detection element. The change of the resistance value of D1B-D4B is shown. Specifically, “+” indicates an increase in resistance value, “−” indicates a decrease in resistance value, and “0” indicates that no significant change occurs in the resistance value. The tables shown in FIGS. 14 (a) and 14 (b) are exactly the same as the table shown in FIG. 8. When each detection element is a piezoresistive element, it is already §1 that such a result is obtained. As explained in.

Here, the resistance values detected by the A system detection elements D1A to D4A are represented as D1A to D4A using the same reference numerals, and the three types of external force components calculated from these resistance values are represented as FzA, MxA, and MyA. If this is the case, each external force component, as shown in the lower part of FIG.
FzA = K1A × (D1A + D2A + D3A + D4A)
MxA = K2A × (D3A−D4A)
MyA = K3A × (D1A−D2A)
(K3A becomes a negative coefficient).

Similarly, resistance values detected by the B system detection elements D1B to D4B are represented as D1B to D4B using the same reference numerals, and three types of external force components calculated from these resistance values are represented as FzB, MxB, and MyB. If this is the case, each external force component, as shown in the lower part of FIG. 14 (b), uses a predetermined proportional coefficient K1B, K2B, K3B,
FzB = K1B × (D1B + D2B + D3B + D4B)
MxB = K2B × (D3B-D4B)
MyB = K3B × (D1B-D2B)
(K3B becomes a negative coefficient).

  Each of the above arithmetic expressions corresponds to the general expression shown in FIG. 11, and each of the proportional coefficients K1A, K2A, K3A, K1B, K2B, K3B is a proportional coefficient with a sign. In addition to serving as a scaling factor, it also serves to correct the sign of each detected value.

  Of course, the sign of each proportionality coefficient changes depending on whether each detection element is arranged on the upper surface or the lower surface of the diaphragm 120 and whether each detection element is a piezoresistive element or a capacitive element. It will be.

  Further, the A system detection elements D1A to D4A are arranged outside the detection points P1 to P4, and the B system detection elements D1B to D4B are arranged inside the detection points P1 to P4. The absolute value of the detection signal value obtained from the A system differs between the A system and the B system. However, if the value of the proportionality coefficient that serves as a scaling factor is appropriately set, the A system detection values A and B The system detection value B can be made equal.

  For example, when an external force −Fz in the negative Z-axis direction is applied to the detection structure, the diaphragm 120 is deformed as shown in FIG. 5A, so that the detection points P1 to P4 are placed on the upper surface of the diaphragm 120. When defined, a compressive force in the radial direction acts in the vicinity of each of the detection points P1 to P4, and “-” is shown in the “−Fz” column of the tables of FIGS. 14 (a) and 14 (b). As shown, the resistance values of the eight detection elements D1A to D4A and D1B to D4B made of piezoresistive elements are all reduced. However, the absolute value of the amount of decrease differs between the A system detection elements D1A to D4A arranged outside the detection points P1 to P4 and the B system detection elements D1B to D4B arranged inside.

  That is, in a state where no external force is applied, even if the resistance values of the eight detection elements D1A to D4A and D1B to D4B are all the same, when the external force -Fz is applied, the A system detection element There will be a difference between the resistance values of D1A to D4A and the B system detection elements D1B to D4B. As a result, the sum of resistance values “D1A + D2A + D3A + D4A” of the A system detection element and the sum of resistance values of the B system detection element “D1B + D2B + D3B + D4B” are not equal.

Still, if you set proportional coefficients K1A and K1B to appropriate values,
FzA = K1A × (D1A + D2A + D3A + D4A)
FzB = K1B × (D1B + D2B + D3B + D4B)
It is possible to adjust so that the detection values FzA and FzB calculated by the two arithmetic expressions are equal to each other.

  Appropriate values for the proportional constants K1A, K2A, K3A, K1B, K2B, and K3B depend on the shape, material, dimensions of each part, position of each detection element, detection characteristics of each detection element, and the like. Therefore, an optimal value may be set through a test using a specific force sensor.

  If each proportionality constant is set to an optimum value, the A system detection value A (specifically, FzA calculated by the above-described arithmetic expression) output from the A system signal processing means 35A shown in FIG. , MxA, MyA) and the B system detection value B output from the B system signal processing means 35B (specifically, FzB, MxB, MyB calculated by the above-described arithmetic expression) are theoretically equal. Become.

  Therefore, in the comparison means 45, the A system detection value A and the B system detection value B are compared, the difference d between them is obtained, and the A system detection value A or the B system detection value B or both are calculated. A predetermined calculated value (for example, an average value of both) is output as a final detected value (in the above example, a detected value of the three-axis components of Fz, Mx, My), and the difference d indicates a predetermined allowable value T If it has exceeded, a difference error is output. If the force sensor is operating normally, the difference d is considered to be within the allowable value T. Therefore, unless the difference error is output from the comparison means 45, the final detection value should be treated as a highly reliable value. Can do.

In the case of a force sensor having a function of detecting the triaxial components Fz, Mx, and My as in the above example, the difference d is obtained for each of these triaxial components. That is,
d (Fz) = absolute value (FzA−FzB)
d (Mx) = absolute value (MxA−MxB)
d (My) = absolute value (MyA−MyB)
Based on the following formula, differences d (Fz), d (Mx), and d (My) of the respective axis components are obtained, and it is determined whether or not these exceed the allowable value T. As the allowable value T, a value common to the three axes may be used. If necessary, an allowable value T (Fz) for the difference d (Fz) and an allowable value T (Mx) for the difference d (Mx). The allowable value T (My) for the difference d (My) may be set.

  If the difference is separately determined for each of the three axis components, for example, a difference error may be output separately for each of the three axis components such as Error (Fz), Error (Mx), and Error (My). it can. In this case, handling of each detection value when a difference error is output may be left to the operation policy of a control device such as a robot in which the force sensor is incorporated. For example, when only the error (Fz) is output together with the final detection values Fz, Mx, and My of the three-axis components, the Mx and My that are not output the difference error may be handled as recognized as normal. However, as long as a differential error is output for Fz, it is possible to handle all detected values as abnormal for safety.

  Of course, the comparison means 45 may output only a single difference error. In this case, if any one of the differences d (Fz), d (Mx), and d (My) between the axis components exceeds the allowable value, a common difference error is output.

  In the case of the embodiment shown here, the comparison means 45 employs an operation in which the output of the difference error and the output of the final detection value are performed separately and independently. Some final detection values (detection values of the triaxial components Fz, Mx, My) are always output. In other words, even when a differential error is output, the output of the final detection value that is inferior in reliability is continued as it is. This is based on a design philosophy that even a final detection value that is inferior in reliability is handled by a policy on the side of a control device such as a robot. Of course, if a difference error is output, it is possible to design to refrain from outputting the final detection value (for example, output a detection value indicating 0) if necessary.

<2-3. Example Using Piezoresistive Element>
Subsequently, an embodiment using a piezoresistive element as the detection element will be described. FIG. 15 is a diagram showing a force sensor according to the present invention in which a piezoresistive element is incorporated as a detection element in the detection structure shown in FIG. Here, FIG. 15A is a side sectional view of the force sensor cut along the XZ plane, and FIG. 15B is a top view of the lower structure 100 of the force sensor.

  In §1-3, the structure and operation of an example of a conventional force sensor using a piezoresistive element as a detection element has been described with reference to FIG. The basic structure and basic operation of the force sensor according to the present invention shown in FIG. 15 are based on the basic structure and basic operation of the conventional force sensor shown in FIG. Therefore, the force sensor according to the present invention shown in FIG. 15 will be described below in comparison with the conventional force sensor shown in FIG.

  First, there is no difference between the two parts of the detection structure. That is, the detection structure used in the force sensor shown in FIG. 15 includes the lower structure 100 and the upper structure 200, and a thin diaphragm portion is used as the elastic deformation portion 120. . In FIG. 15 as well, for convenience of explanation, an XYZ three-dimensional orthogonal coordinate system as shown is defined with the center of the diaphragm 120 as the origin O. The upper surface of the lower structure 100 (the upper surface of the diaphragm portion 120) is referred to as a detection reference surface. The detection reference plane is a plane for arranging a plurality of n detection points, and the XY plane may be the detection reference plane. In the illustrated embodiment, each piezoresistive element is the upper surface of the diaphragm unit 120. Therefore, for the sake of convenience, the upper surface of the diaphragm 120 (a plane parallel to the XY plane) is set as the detection reference plane.

  As shown in FIG. 15 (b), when a detection reference circle G1 (indicated by a one-dot chain circle in the figure) centered on the Z axis is drawn on this detection reference plane, four detection points P11 to P14 are obtained. , Both are located on the detection reference circle G1. In other words, the four detection points P <b> 11 to P <b> 14 are all arranged at the same distance (the radius of the detection reference circle G <b> 1) from the Z axis on the upper surface of the lower structure 100. Moreover, the detection points P11 and P12 are arranged on a straight line along the X axis, and the detection points P13 and P14 are arranged on a straight line along the Y axis. Such a geometric configuration has a merit that the signal processing by the signal processing means can be simplified because symmetry is generated in the arrangement of the detection elements and the value of the detection signal is also symmetric. .

  A feature of the embodiment using the piezoresistive element described here is that a plurality of n detection points are defined in the diaphragm unit 120, and the i-th detection point Pi (i satisfies 1 ≦ i ≦ n). Two sets of piezoresistive elements, i.e., a piezoresistive element that constitutes the i-th A-system detection element DiA and a piezoresistive element that constitutes the i-th B-system detection element DiB, are arranged in the vicinity of It is in the point. Here, the i-th A-system detection element DiA is configured by a piezoresistive element disposed in the first vicinity of the i-th detection point Pi, and the deflection generated in the vicinity is determined by the electric resistance value. A detection signal indicated as a change is output, and the i-th B system detection element DiB is configured by a piezoresistive element arranged in the second vicinity of the i-th detection point Pi, and is generated in the vicinity A detection signal indicating deflection as a change in electric resistance value is output.

  The specific example shown in FIG. 15 is an example in which n = 4 is set. For convenience of explanation, as described above, a detection reference plane is defined on the upper surface of the diaphragm section 120, and the X axis and the Y axis are If an X-axis projection image and a Y-axis projection image obtained by projecting on the detection reference plane are defined, the following configuration is provided. First, since n = 4 is set, four detection points are defined on the detection reference plane. Here, as shown in FIG. 15B, if a detection reference circle G1 centered on the Z-axis is drawn on the detection reference plane, the first detection point P11 is a positive X-axis projection image and a detection reference circle. Located at the intersection with G1, the second detection point P12 is located at the intersection between the negative X-axis projection image and the detection reference circle G1, and the third detection point P13 is detected as the positive Y-axis projection image. Located at the intersection with the reference circle G1, the fourth detection point P14 is located at the intersection between the negative Y-axis projection image and the detection reference circle G1.

  For each of the detection points P11 to P14, if the side far from the Z axis is referred to as the outside, and the side close to the Z axis is referred to as the inside, the detection points P11 to P14 have 4 A set of A-system detection elements and 4 sets of B-system detection elements are provided, and detection of the triaxial components Fz, Mx, My is performed based on detection signals from all eight sets of detection elements. become.

  Specifically, first, the first A-system detection element is composed of a piezoresistive element R1A arranged along the X-axis projection image outside the first detection point P11, and the first B-system detection element. The detection element is composed of a piezoresistive element R1B arranged along the X-axis projection image inside the first detection point P11. Similarly, the second A-system detection element is composed of a piezoresistive element R2A arranged along the X-axis projection image outside the second detection point P12, and the second B-system detection element is It consists of a piezoresistive element R2B arranged along the X-axis projection image inside the second detection point P12. These piezoresistive elements R1A, R1B, R2B, and R2A are all arranged so that their longitudinal directions (directions as resistive elements) are along the X axis.

  The third A-system detection element is composed of a piezoresistive element R3A arranged along the Y-axis projection image outside the third detection point P13, and the third B-system detection element is It consists of a piezoresistive element R3B arranged along the Y-axis projection image inside the third detection point P13. Further, the fourth A-system detection element is composed of a piezoresistive element R4A arranged along the Y-axis projection image outside the fourth detection point P14, and the fourth B-system detection element is It consists of a piezoresistive element R4B arranged along the Y-axis projection image inside the fourth detection point P14. These piezoresistive elements R3A, R3B, R4B, and R4A are all arranged so that their longitudinal directions (directions as resistive elements) are along the Y axis.

  In the case of the embodiment shown in FIG. 15, the upper surface of the diaphragm unit 120 is used as a detection reference surface, the detection points P11 to P14 are arranged on the upper surface of the diaphragm unit 120, and each piezoresistive element is embedded in the upper surface of the diaphragm unit 120. However, the lower surface of the diaphragm unit 120 may be used as a detection reference surface, the detection points P11 to P14 may be arranged on the lower surface of the diaphragm unit 120, and the piezoresistive elements may be embedded in the lower surface of the diaphragm unit 120. Absent. In either case, each piezoresistive element outputs the deflection generated at the embedded position as a change in electrical resistance value. Specifically, in the embodiment shown in FIG. 15, the resistance value changes as shown in the tables of FIGS. 14A and 14B occur due to the action of the triaxial components Fz, Mx, and My.

  Therefore, as shown in FIG. 12 (c), if the A-system signal processing means 35A and the B-system signal processing means 35B are provided, the three-axis component Fz can be calculated by calculation based on the detection signals from the eight detection elements. , Mx, My can be output as final detection values.

Specifically, if the resistance values of the eight sets of piezoresistive elements R1A to R4A and R1B to R4B are expressed as R1A to R4A and R1B to R4B using the same reference numerals,
The A system signal processing means 35A uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (R1A + R2A + R3A + R4A)
MxA = K2A × (R3A-R4A)
MyA = K3A × (R1A-R2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are A system detection value A shown can be output.

On the other hand, the B system signal processing means 35B uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (R1B + R2B + R3B + R4B)
MxB = K2B × (R3B-R4B)
MyB = K3B × (R1B-R2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X axis, and the moment component MyB around the Y axis are obtained. The B system detection value B shown can be output.

  Therefore, as described above, the comparing means 45 compares the A system detection value A and the B system detection value B to obtain the difference d between them, and based on the A system detection value A or the B system detection value B or both. Is output as final detection values Fz, Mx, My, and if the difference d exceeds a predetermined allowable value T, a difference error is output. Output.

  As described above, in order to implement the present invention, it is preferable that all the detection points are arranged on the detection reference circle G1. This is because by arranging all the detection points on the detection reference circle G1, symmetry can be obtained in the arrangement of each detection element, and the symmetry of the detection signal value can also be obtained by the signal processing means. This is because signal processing can be simplified.

For example, in the above example, the piezoresistive elements R1A and R2A have symmetry with respect to the YZ plane, and the piezoresistive elements R3A and R4A have symmetry with respect to the XZ plane. For this reason, in the state where no external force is acting,
MxA = K2A × (R3A-R4A)
MyA = K3A × (R1A-R2A)
Therefore, the zero point correction process for the outputs of MxA and MyA can be omitted.

Similarly, in the case of the above example, the piezoresistive elements R1B and R2B have symmetry with respect to the YZ plane, and the piezoresistive elements R3B and R4B have symmetry with respect to the XZ plane. For this reason, in the state where no external force is acting,
MxB = K2B × (R3B-R4B)
MyB = K3B × (R1B-R2B)
Since both of the calculation results are 0, the zero point correction process for the MxB and MyB outputs can be omitted.

<2-4. Example Using Capacitance Element>
Subsequently, an embodiment using a capacitive element as a detection element will be described. FIG. 16 is a diagram showing a force sensor according to the present invention in which a capacitive element is incorporated as a detection element in the detection structure shown in FIG. Here, FIG. 16A is a side sectional view of the force sensor cut along the XZ plane, and FIG. 16B is a bottom view of the lower structure 100 of the force sensor (from the bottom). (Because this is a looked up view, the Y-axis faces downward).

  In §1-4, the structure and operation of an example of a conventional force sensor using a capacitive element as a detection element has been described with reference to FIG. The basic structure and basic operation of the force sensor according to the present invention shown in FIG. 16 are based on the basic structure and basic operation of the conventional force sensor shown in FIG. Therefore, the force sensor according to the present invention shown in FIG. 16 will be described below in comparison with the conventional force sensor shown in FIG.

  First, there is no difference between the two parts of the detection structure. That is, the detection structure used in the force sensor shown in FIG. 16 includes the lower structure 100 and the upper structure 200, and a thin plate-like diaphragm portion is used as the elastic deformation portion 120. . In FIG. 16 as well, for convenience of explanation, an XYZ three-dimensional orthogonal coordinate system as shown is defined with the center of the diaphragm 120 as the origin O. And the lower surface of the diaphragm part 120 will be called a detection reference plane. The detection reference plane is a plane on which a plurality of n detection points are arranged. The upper surface of the diaphragm 120 or the XY plane may be used as a detection reference plane, but a displacement electrode is arranged below the diaphragm 120. In relation to this, here, the lower surface of the diaphragm 120 (a plane parallel to the XY plane) is set as the detection reference plane.

  As shown in FIG. 16 (b), when a detection reference circle G1 (shown by a one-dot chain line in the figure) centered on the Z-axis is drawn on the detection reference plane, four detection points P21 to P24 are drawn. Are both located on the detection reference circle G1. In other words, the four detection points P <b> 21 to P <b> 24 are all arranged at the same distance (the radius of the detection reference circle G <b> 1) from the Z axis on the lower surface of the diaphragm portion 120. Moreover, the detection points P21 and P22 are arranged on a straight line along the X axis, and the detection points P23 and P24 are arranged on a straight line along the Y axis. As described above, such a geometric configuration creates symmetry in the arrangement of each detection element, and also provides symmetry in the value of the detection signal, thus simplifying signal processing by the signal processing means. There is a merit that can be done.

  A feature of the embodiment using the capacitive element described here is that a plurality of n detection points are defined in the diaphragm unit 120, and the i-th detection point Pi (i satisfies 1 ≦ i ≦ n). In the vicinity of (an arbitrary integer), two sets of capacitive elements, i.e., a capacitive element constituting the i-th A-system detection element DiA and a capacitive element constituting the i-th B-system detection element DiB are arranged. .

  The specific example shown in FIG. 16 is an example in which n = 4 is set. As described above, the detection reference plane is defined on the lower surface of the diaphragm 120, and the X axis and the Y axis are defined as the detection reference plane. If an X-axis projection image and a Y-axis projection image obtained by projection are defined and a detection reference circle G1 centered on the Z axis is drawn on the detection reference plane, the first detection point P21 is a positive X-axis projection. The second detection point P22 is located at the intersection of the negative X-axis projection image and the detection reference circle G1, and the third detection point P23 is positive Y. The fourth detection point P24 is located at the intersection between the negative projected image and the detection reference circle G1, and is located at the intersection between the axial projection image and the detection reference circle G1.

  Further, as shown in FIG. 16 (b), eight semicircular displacement electrodes E21A, E21B, E22A, E22B, E23A, E23B, E24A, E24B are arranged on the lower surface of the diaphragm 120, Eight semicircular fixed electrodes E11A and E11B are formed on the support substrate 300 (a disk-shaped substrate whose outer peripheral portion is fixed to the inner peripheral surface of the support portion 110) so as to face the eight displacement electrodes. , E12A, E12B, E13A, E13B, E14A, E14B (the planar arrangement pattern is the same as the arrangement pattern of the eight displacement electrodes shown in FIG. 16B). A capacitive element is formed by the individual displacement electrodes and the individual fixed electrodes opposed thereto. In FIG. 16B, the eight capacitive elements formed in this way are indicated by parenthesized symbols C1A, C1B, C2A, C2B, C3A, C3B, C4A, and C4B.

  It is also possible to adopt a structure in which the displacement electrode is provided not on the bottom surface of the diaphragm portion 120 but on the top surface, and the fixed electrode is disposed above the displacement electrode (that is, the capacitor element is disposed above the diaphragm portion 120). However, as shown in FIG. 16 (a), when the detection structure in which the force receiving portion 210 is disposed above the diaphragm portion 120 is used, the displacement electrode is connected to the diaphragm portion 120 as shown in the drawing. The overall structure can be simplified by adopting the structure provided on the lower surface (that is, the structure in which the capacitive element is disposed below the diaphragm portion 120).

  Eventually, for an arbitrary i (1 ≦ i ≦ n), the i-th A-system detection element DiA is the i-th A-system displacement electrode disposed in the first vicinity of the i-th detection point Pi. And an i-th A-system capacitive element CiA having an i-th A-system fixed electrode fixed to the support 110 so as to face the i-th A-system displacement electrode, A detection signal indicating a displacement generated in the vicinity of 1 as a change in capacitance value is output. The i-th B-system detection element DiB is connected to the i-th B-system displacement electrode disposed in the second vicinity of the i-th detection point Pi, and the i-th B-system displacement electrode. The i-th B-system capacitive element CiB having an i-th B-system fixed electrode fixed to the support portion 110 so as to face each other, and the displacement generated in the second vicinity is electrostatic capacitance A detection signal indicated as a change in value is output.

  Here, for each of the detection points P21 to P24, if the side far from the Z axis is referred to as the outside and the side close to the Z axis is referred to as the inside, Four sets of A-line detection elements and four sets of B-line detection elements are provided, and the detection of the triaxial components Fz, Mx, My is performed based on detection signals from all the eight sets of detection elements. It will be.

  Specifically, first, the first A-system detection element is composed of a capacitive element C1A (displacement electrode E21A and fixed electrode E11A) arranged outside the first detection point P21. A system | strain detection element consists of capacitive element C1B (displacement electrode E21B and fixed electrode E11B) arrange | positioned inside the 1st detection point P21. Similarly, the second A-system detection element is composed of a capacitive element C2A (displacement electrode E22A and fixed electrode E12A) arranged outside the second detection point P22, and the second B-system detection element is The capacitive element C2B (displacement electrode E22B and fixed electrode E12B) disposed inside the second detection point P22.

  The third A-line detection element is composed of a capacitive element C3A (displacement electrode E23A and fixed electrode E13A) arranged outside the third detection point P23, and the third B-line detection element is It consists of a capacitive element C3B (displacement electrode E23B and fixed electrode E13B) arranged inside the third detection point P23. And the 4th A system detection element consists of capacitive element C4A (displacement electrode E24A and fixed electrode E14A) arranged outside the 4th detection point P24, and the 4th B system detection element is The capacitive element C4B (displacement electrode E24B and fixed electrode E14B) is arranged inside the fourth detection point P24.

  These eight sets of capacitive elements output the displacement generated at the position where each displacement electrode is fixed as a change in capacitance value. Specifically, in the case of the embodiment shown in FIG. 16, due to the action of the triaxial components Fz, Mx, My, both the A-system capacitive element and the B-system capacitive element are as shown in the table of FIG. 9. A change in capacitance value will occur. Therefore, as shown in FIG. 12 (c), if the A-system signal processing means 35A and the B-system signal processing means 35B are provided, the three-axis component Fz can be calculated by calculation based on the detection signals from the eight detection elements. , Mx, My can be output as final detection values.

Specifically, if the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B using the same reference numerals,
The A system signal processing means 35A uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are A system detection value A shown can be output.

On the other hand, the B system signal processing means 35B uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X axis, and the moment component MyB around the Y axis are obtained. The B system detection value B shown can be output.

  Therefore, as described above, the comparing means 45 compares the A system detection value A and the B system detection value B to obtain the difference d between them, and based on the A system detection value A or the B system detection value B or both. Is output as final detection values Fz, Mx, My, and if the difference d exceeds a predetermined allowable value T, a difference error is output. Output.

  Also in the embodiment shown in FIG. 16, since all the detection points P21 to P24 are arranged on the detection reference circle G1, symmetry is obtained in the arrangement of each detection element, and the value of the detection signal is also symmetric. And the advantage that the signal processing by the signal processing means can be simplified.

For example, the capacitive elements C1A and C2A have symmetry with respect to the YZ plane, and the capacitive elements C3A and C4A have symmetry with respect to the XZ plane. For this reason, in the state where no external force is acting,
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
Therefore, the zero point correction process for the outputs of MxA and MyA can be omitted.

Similarly, the capacitive elements C1B and C2B have symmetry with respect to the YZ plane, and the capacitive elements C3B and C4B have symmetry with respect to the XZ plane. For this reason, in the state where no external force is acting,
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
Since both of the calculation results are 0, the zero point correction process for the MxB and MyB outputs can be omitted.

<2-5. Signal processing means and comparison means>
As explained in §2-1, the force sensor according to the present invention is characterized by n external forces applied to a single detection structure 10 as shown in the block diagram of FIG. The A system detection element 25A and the n B system detection elements 25B respectively detect the detection signals obtained from the A system detection element 25A and the B system signal processing means 35B. The system detection value A and the system B detection value B are obtained, and the comparison means 45 compares them.

  For example, the basic configuration of the force sensor according to the embodiment shown in FIG. 16 described in §2-4 is shown in FIG. 17 as a block diagram following FIG. 12 (c). In this case, the detection structure 10 is constituted by a laminated structure of the lower structure 100 and the upper structure 200 as shown in FIG. Further, as shown in FIG. 16 (b), the A system detection element 25A is composed of four sets of A system capacitance elements C1A to C4A, and the B system detection element 25B is composed of four sets of B system capacitance elements. It is comprised by C1B-C4B.

  Then, detection signals indicating capacitance values C1A to C4A indicated by the same reference numerals are output from the A-system capacitive elements C1A to C4A, respectively, and are provided to the A-system signal processing means 35A. Similarly, detection signals indicating electrostatic capacitance values C1B to C4B indicated by the same reference numerals are output from the B system capacitive elements C1B to C4B, respectively, and are provided to the B system signal processing means 35B. Actually, an electric circuit (for example, a C / V conversion circuit) for taking in the capacitance value between a pair of electrodes constituting each capacitive element as an electric signal at the input stage of each signal processing means 35A, 35B. Is equipped.

  The A-system signal processing means 35A performs, based on the detected signals C1A to C4A, the arithmetic processing based on the arithmetic expression as shown in the figure or the signal processing corresponding to the arithmetic processing, thereby performing triaxial components FzA, MxA, MyA is output as the A system detection value A. Similarly, the B-system signal processing means 35B performs the arithmetic processing based on the arithmetic expression as shown on the basis of the captured detection signals C1B to C4B or the signal processing corresponding to the arithmetic processing, thereby performing the triaxial component FzB. , MxB, MyB are output as the B system detection value B.

  When the captured detection signal is converted into a digital signal and processed, each detection value can be obtained by arithmetic processing using a digital circuit such as a logic element or a microprocessor. Actually, the detection signal is captured at a predetermined sampling period, and the detection values A and B are output at each sampling period. When the captured detection signal is processed as an analog signal, signal processing corresponding to necessary calculation processing may be executed by an analog circuit.

  The A system detection value A (FzA, MxA, MyA) and the B system detection value B (FzB, MxB, MyB) obtained in this way are given to the comparison means 45. This comparison means 45 may also be constituted by a digital circuit using a logic element or a microprocessor, or may be constituted by an analog circuit capable of executing equivalent processing. In the block diagram of FIG. 17, the A system signal processing means 35A, the B system signal processing means 35B, and the comparison means 45 are depicted as separate blocks, but these constituent elements are digital circuits using a microprocessor. May be incorporated in the same IC chip.

  In short, the A system signal processing means 35A and the B system signal processing means 35B only need to be configured to input signals of different systems and output signals of different systems, respectively. If the processing is performed separately and independently, the redundancy required for the present invention can be secured. Of course, in order to increase redundancy, the A system signal processing means 35A, the B system signal processing means 35B, and the comparison means 45 may all be configured by separate IC chips.

  The first role of the comparison unit 45 is to output a detection value A or a detection value B or a predetermined calculation value calculated based on both as a final detection value. For example, the A system may be determined as the main system and the B system as the sub system, and the A system detection value A may always be output as the final detection values Fz, Mx, My. In this case, the B system detection value B is used only for comparison with the A system detection value A. Of course, the A system may be determined as the sub-system and the B system as the main system. Alternatively, an average value of the A system detection value A and the B system detection value B may be calculated, and the average value may be output as the final detection value. In this case, each final detection value is obtained by the calculation of Fz = (FzA + FzB) / 2, Mx = (MxA + MxB) / 2, My = (MyA + MyB) / 2.

The second role of the comparison means 45 is to compare the A system detection value A and the B system detection value B, find the difference d between the two, and if the difference d exceeds a predetermined allowable value T, It is to output a difference error. Specifically, as described in §2-2,
d (Fz) = absolute value (FzA−FzB)
d (Mx) = absolute value (MxA−MxB)
d (My) = absolute value (MyA−MyB)
Based on the following formula, differences d (Fz), d (Mx), and d (My) of the respective axis components are obtained, and it is determined whether or not these exceed the allowable value T. As the allowable value T, a value common to the three axes may be set, or a different value may be set for each. Also, the difference error output method may output a separate error for each of the three axis components, or output a common difference error when an error occurs for at least one axis component. Also good.

  As described above, if a difference error is output from the comparison unit 45, a control device such as a robot incorporating the force sensor can perform appropriate control based on the difference error. However, in the embodiment shown here, the comparison means 45 is also provided with a function for outputting a range-out error in addition to the difference error. This range-out error is an error indicating that the A system detection value A or the B system detection value B exceeds a predetermined allowable range.

  In general, in the case of a sensor that outputs some detection value as an electric signal, a predetermined allowable range is set for the detection value to be output, and only a detection value within the allowable range is guaranteed as an appropriate detection value. Normally, even if an output that exceeds this allowable range is made slightly, a design with a margin is often made so as not to immediately cause damage to the detection structure. A detection value exceeding the allowable range is not a proper detection value guaranteed by the sensor.

  Therefore, in the embodiment shown here, a function for outputting a range-out error is added to the comparison means 45. That is, the comparison means 45 determines whether or not each of the A system detection value A and the B system detection value B is within a predetermined allowable range, and if it exceeds the allowable range, a range out error is generated. Perform output processing. Eventually, from the comparison means 45, in addition to the final output values Fz, Mx, My, if the difference d exceeds a predetermined allowable value T, a difference error is output, and the detection values A, B are predetermined. If the allowable range is exceeded, a range-out error is output.

  FIG. 18 is a flowchart showing a specific processing procedure of the comparison means 45 shown in FIG. First, in step S1, A system detection value A and B system detection value B are input. Actually, the detection values A and B are input at a predetermined sampling period. Each of the above-described embodiments is an example of a force sensor having a detection function of the three-axis components Fz, Mx, and My. Therefore, the detection value A is a three-axis component of FzA, MxA, and MyA, and the detection value B Is a triaxial component of FzB, MxB, and MyB.

  In the subsequent step S2, a specific axis component is extracted from the input detection values A and B. As described above, since the detection values A and B for the three-axis components Fz, Mx, and My are input in step S1, first, in step S2, there is only one specific axis component for this three-axis component. Will be extracted. Here, first, let us assume that the component Fz is extracted as a specific axial component. Specifically, FzA is extracted as the detection value A, and FzB is extracted as the detection value B.

  In step S3, it is determined whether or not the input detection values A and B are within a predetermined allowable range. In the case of the example shown here, the allowable range R (Fz) is set for FzA and FzB, the allowable range R (Mx) is set for MxA and MxB, and the allowable range R (My) is set for MyA and MyB. Thus, it is determined whether each is within the set allowable range. Therefore, when FzA is extracted as the detection value A and FzB is extracted as the detection value B in step S2, it is determined whether or not these detection values A and B are within the allowable range R (Fz). Of course, a common allowable range may be set for the three-axis components.

  If it is determined in step S3 that both the detected values A and B are within the allowable range, the process proceeds to step S4, and the difference d is calculated as the absolute value of the difference between the detected values A and B. . In the case of the above example, the absolute value of the difference between FzA and FzB is calculated as the difference d (Fz). In step S5, it is determined whether or not the difference d exceeds a predetermined allowable value T. If the difference d exceeds the allowable value T, the process proceeds to step S7, and a differential error is output. As described above, the tolerance value T may be set separately for each axis component, or a common tolerance value may be set. Further, the difference error may include information indicating a specific axis component (Fz in the above example) in which the error has occurred, as necessary.

  Subsequently, in step S6, a process of outputting the detection value A or B or its average value as the final detection value is performed. As described above, when the A system is defined as the main system and the B system is defined as the sub system, in step S6, only the A system detection value is always output as the final detection value (in the above example, FzA Is output as the final detection value Fz as it is). On the other hand, when the average value of both is adopted, in step S6, the average value of the detection values A and B is output as the final detection value (in the above example, obtained by the calculation Fz = (FzA + FzB) / 2). Value is output as the final detection value Fz).

  On the other hand, if it is determined in step S3 that one of the detection values A and B is within the allowable range but the other is out of the allowable range, the process proceeds to step S8, and a range out error is output. Done. For this range-out error, if necessary, information indicating the specific axis component (Fz in the above example) where the error has occurred, and information indicating which of the A system / B system is out of range. It may be included. In step S9, the detected value A or B within the allowable range is output as the final detected value.

  If it is determined in step S3 that both detection values A and B exceed the allowable range, the process proceeds to step S10, and a range out error is output. For this range-out error, if necessary, information indicating a specific axis component (Fz in the above example) in which the error has occurred, or information indicating that both of the A system / B system are out of range. May be included. In step S11, instead of the detection values A and B, a predetermined dummy value is output as the final detection value.

  As the dummy value output in step S11, a predetermined value within the allowable range is set in advance. For example, a detection value (a value indicating a zero point) output when no external force is applied may be set as a dummy value. The reason for outputting the dummy value within the allowable range instead of the detection values A and B is that if a value exceeding the allowable range is output as the final detection value, a device that uses the final detection value (for example, a robot) This is because an unexpected failure may occur in the control device.

  As described above, the allowable range is a range of an appropriate detection value guaranteed by the force sensor, and a robot control device or the like is designed on the assumption that the detection value is within the allowable range. Will be. For this reason, if a value exceeding the allowable range is output as the final detection value, an unexpected situation may occur in the robot control device or the like that has received the final detection value.

  Therefore, in the processing in the comparison means 45, if both the detection values A and B exceed the allowable range, a range out error is output to notify the abnormality, and the final detection value is a dummy within the allowable range. The value is output. This dummy value is of course not a correct detection value, but a robot control device or the like can recognize that the dummy value is not a correct detection value by receiving a notification of a range-out error. Does not occur.

  Thus, when the process for the specific axis component extracted in step S2 (Fz in the above example) is completed, the process returns to step S2 again via step S12, and another specific axis component (for example, Mx or My). ), The same processing is repeated. Thus, when the processing for all the axis components (in the above example, the three-axis components Fx, Mx, My) is completed, the processing of the comparison means 45 (processing for the detection values A, B input in one sampling period) Ends.

  In short, in the case of the embodiment shown in the flowchart of FIG. 18, when only the A system detection value A exceeds the allowable range, the comparison means 45 outputs the B system detection value B as the final detection value, When only the B system detection value B exceeds the allowable range, the A system detection value A is output as the final detection value, and both the A system detection value A and the B system detection value B exceed the allowable range. Performs processing for outputting a predetermined dummy value within the allowable range as the final detection value.

<<< §3. Modification of the present invention >>
So far, in §2, the basic embodiment of the force sensor according to the present invention has been described. Here, some modifications to these basic embodiments will be described.

<3-1. Modified example in which arrangement of detection elements is changed>
FIG. 19 is a side sectional view (FIG. 19A) showing a modification of the force sensor shown in FIG. 16, and a bottom view of the lower structure 100 (FIG. 19B). The force sensor shown in FIG. 16 is different from the force sensor shown in FIG. 19 only in the arrangement of eight detection elements (capacitance elements). Accordingly, the reference numerals of the constituent elements of the force sensor shown in FIG. 19 are the same as those of the corresponding constituent elements of the force sensor shown in FIG.

  The force sensor shown in FIG. 19 has the same detection structure as the detection structure shown in FIG. 16, and a detection reference plane is defined on the lower surface of the diaphragm portion 120. Four detection points P21 to P24 are defined. The positions of the detection points P21 to P24 are also exactly the same as in the embodiment shown in FIG. In addition, in order to detect displacement generated in the vicinity of these four detection points P21 to P24, four sets of A-system detection elements and four sets of B-system detection elements are formed. The same as the embodiment shown in FIG. However, the arrangement of the detection elements is slightly different.

  The embodiment shown in FIG. 16 is an example in which capacitive elements are arranged according to the basic arrangement policy of the detection elements shown in FIG. The basic arrangement policy shown in FIG. 13 is that the A system detection element is arranged in the vicinity of the outside of each detection point, and the B system detection element is arranged in the vicinity of the inside of each detection point. It was. For this reason, in FIG. 13, four sets of A system detection elements D1A to D4A are arranged outside the detection points P1 to P4, and four sets of B system detection elements D1B to D4B are arranged inside the detection points P1 to P4. An example is shown.

  On the other hand, the basic arrangement policy of the detection elements in the modification shown in FIG. 19 is that the A system detection element and the B system detection element are adjacently arranged on both sides of the X axis or the Y axis, respectively. Is.

  Specifically, as shown in FIG. 19 (b), the first A-system detection element C1A electrically detects the displacement generated in the vicinity of the first detection point P21 where the Y coordinate value is negative. The first B-system detection element C1B can electrically detect the displacement generated in the vicinity of the first detection point P21 where the Y coordinate value is positive. It is arranged in the position. Similarly, the second A-system detection element C2A is arranged at a position where the displacement generated in the vicinity of the second detection point P22 where the Y coordinate value is negative can be electrically detected. The second B system detection element C2B is arranged at a position where the displacement generated in the vicinity of the second detection point P22 where the Y coordinate value is positive can be electrically detected.

  The third A-system detection element C3A is arranged at a position where the displacement generated in the vicinity of the third detection point P23 where the X coordinate value is negative can be electrically detected. The B-th system detection element C3B is arranged at a position where the displacement generated in the vicinity of the third detection point P23 where the X coordinate value is positive can be electrically detected. Further, the fourth A-system detection element C4A is disposed at a position where the displacement generated in the vicinity of the fourth detection point P24 where the X coordinate value is negative can be electrically detected. The B-th system detection element C4B is arranged at a position where the displacement generated in the vicinity of the fourth detection point P24 where the X coordinate value is positive can be electrically detected.

  In the case of the modification shown in FIG. 19, as in the embodiment shown in FIG. 16, an electrode support substrate 300 fixed to the support portion 110 is provided, and a fixed electrode fixed on the electrode support substrate 300 is used. As a result, a total of eight capacitive elements are formed, and these capacitive elements are used as detection elements.

  That is, each of the capacitive elements C1A to C4A and C1B to C4B includes semicircular displacement electrodes E21A to E24A and E21B to E24B fixed to the lower surface of the diaphragm 120, and the electrode support substrate 300 so as to face these displacement electrodes. The semi-circular fixed electrodes E11A to E14A and E11B to E14B fixed on the top, and the function of outputting the displacement generated at the position where each displacement electrode is fixed as the change in the capacitance value Have

  Specifically, the first A-line detection element is from a capacitive element C1A (displacement electrode E21A and fixed electrode E11A) arranged in the vicinity of the first detection point P21 where the Y coordinate value is negative. Thus, the first B-system detection element is composed of a capacitive element C1B (displacement electrode E21B and fixed electrode E11B) arranged in the vicinity of the first detection point P21 where the Y coordinate value is positive. Similarly, the second A-system detection element includes a capacitive element C2A (displacement electrode E22A and fixed electrode E12A) disposed in the vicinity of the second detection point P22 where the Y coordinate value is negative. The second B-system detection element includes a capacitive element C2B (displacement electrode E22B and fixed electrode E12B) arranged in the vicinity of the second detection point P22 where the Y coordinate value is positive.

  The third A-system detection element includes a capacitive element C3A (displacement electrode E23A and fixed electrode E13A) disposed in the vicinity of the third detection point P23 where the X coordinate value is negative. The third B-system detection element includes a capacitive element C3B (displacement electrode E23B and fixed electrode E13B) disposed in the vicinity of the third detection point P23 where the X coordinate value is positive. Further, the fourth A-system detection element is composed of a capacitive element C4A (displacement electrode E24A and fixed electrode E14A) arranged in the vicinity of the fourth detection point P24 where the X coordinate value is negative. The fourth B-system detection element includes a capacitive element C4B (displacement electrode E24B and fixed electrode E14B) arranged in the vicinity of the fourth detection point P24 where the X coordinate value is positive.

  As described above, the arrangement of the detection elements of the force sensor shown in FIG. 19 is slightly different from the arrangement of the detection elements of the force sensor shown in FIG. Each of the B system detection elements detects a displacement in the vicinity of the first detection point P21, and both the second A system detection element and the second B system detection element are the second ones. A displacement in the vicinity of the detection point P22 is detected, and the third A-line detection element and the third B-line detection element both detect a displacement in the vicinity of the third detection point P23, and The 4th A system detection element and the 4th B system detection element remain unchanged in the essential feature that both detect the displacement in the vicinity of the fourth detection point P24.

  Accordingly, in the case of the force sensor shown in FIG. 19, it is possible to detect the triaxial components Fz, Mx, and My by performing the same signal processing as that of the force sensor shown in FIG.

That is, if the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B using the same symbols, respectively, the A-system signal processing means 35A has a predetermined signed proportionality. Using the coefficients K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
The A system detection value A indicating FzA, MxA, MyA can be output by performing the following arithmetic processing or signal processing corresponding to the arithmetic processing.

Similarly, the B system signal processing means 35B uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
The B system detection value B indicating FzB, MxB, MyB can be output by performing the following arithmetic processing or signal processing corresponding to the arithmetic processing.

<3-2. Modified example with auxiliary system signal processing>
In §3-1 described above, the modification in which the arrangement of the detection elements is changed has been described with reference to FIG. The feature of this modification is that the arrangement pattern of the A system detection element and the B system detection element is not divided on the inside or outside of the detection point, but on the positive side or the negative side of the coordinate axis. As described above, when the arrangement pattern divided on the positive side or the negative side of the coordinate axis is employed, in addition to the A system signal processing and the B system signal processing, it is possible to obtain an advantage that the auxiliary system signal processing can be further added. Here, a modified example in which the auxiliary system signal processing is added will be described.

  FIG. 20 is a block diagram showing a basic configuration when auxiliary system signal processing is added to the force sensor shown in FIG. In §2-5, the signal processing for the force sensor shown in FIG. 16 has been described with reference to the block diagram of FIG. 17, but here, the force shown in FIG. 19 will be described with reference to the block diagram of FIG. Signal processing (an example in which auxiliary system signal processing is added) for the sense sensor will be described.

  In the block diagram shown in FIG. 20, the auxiliary system signal processing means 35C is added to the block diagram shown in FIG. 17, and the auxiliary system detection value C output from the auxiliary system signal processing means 35C is considered in the comparison means 45. The processing is executed. The A system detection element 25A and the B system detection element 25B are configured by capacitive elements C1A to C4A and C1B to C4B adopting the arrangement pattern shown in FIG. 19, but the A system signal processing means 35A and the B system signal processing means. The signal processing executed in 35B is not different from the processing described in §2-5.

  That is, in the A system signal processing means 35A, arithmetic processing based on the arithmetic expression described in the illustrated block or signal processing corresponding to the arithmetic processing is executed, and the A system detection value A (FzA, MxA, MyA) is obtained. In the B system signal processing means 35B, the arithmetic processing based on the arithmetic expression described in the illustrated block or the signal processing corresponding to the arithmetic processing is executed, and the B system detection value B (FzB, MxB, MyB) Is output.

  On the other hand, the auxiliary system signal processing means 35C includes detection signals (capacitance values C1A to C4A) from the A system detection element 25A, detection signals (capacitance values C1B to C4B) from the B system detection element 25B, and And MxC and MyC are output as auxiliary system detection values C by performing arithmetic processing based on arithmetic expressions described in the illustrated block or signal processing corresponding to the arithmetic processing. The auxiliary system detection value C is a value obtained by a calculation process different from the A system detection value A and the B system detection value B, but is not a detection value of a completely independent third system, but the A system and B It is a value obtained by calculation processing that mixes the system.

Specifically, the auxiliary system signal processing means 35C uses predetermined signed proportional coefficients K2C and K3C,
MxC = K2C × ((C1A + C2A) − (C1B + C2B))
MyC = K3C × ((C3B + C4B) − (C3A + C4A))
The auxiliary system detection value C indicating the moment component MxC around the X axis and the moment component MyC around the Y axis of the external force is output by performing the following calculation processing or signal processing corresponding to the calculation processing.

  The reason why the moment component MyC around the Y-axis can be obtained based on the above arithmetic expression can be understood with reference to the modification shown in FIG. When the deformation mode occurs, the detection point P21 is displaced downward and the detection point P22 is displaced upward, so that the capacitance values of the capacitive elements C1A, C1B, C2A, C2B shown in FIG. fluctuate. On the other hand, when attention is paid to the displacement in the vicinity of the detection points P23 and P24 shown in FIG. 19 (b), the displacement is not as large as that in the vicinity of the detection points P21 and P22. It can be seen that the part where the X coordinate value is positive is displaced downward, and the left part of the figure (the part where the X coordinate value is negative) is displaced upward.

  Therefore, with the Y axis as a boundary, the capacitance values of the capacitive elements C3B and C4B arranged on the right side of the figure increase, and the capacitance values of the capacitive elements C3A and C4A arranged on the left side of the figure decrease. It will be. The above formula MyC = K3C × ((C3B + C4B) − (C3A + C4A)) is a calculation formula based on such a phenomenon. The reason why the moment component MxC around the X axis is obtained by the above-described equation MxC = K2C × ((C1A + C2A) − (C1B + C2B)) is also the same.

  Of course, the fluctuation amount of the capacitance value used for calculating the auxiliary system detection value C (MxC, MyC) is the fluctuation amount of the capacitance value used for calculating the A system detection value A and the B system detection value B. Since it is small, the accuracy of the auxiliary system detection value C is lower than the accuracy of the A system detection value A and the B system detection value B. Therefore, this auxiliary system detection value C is not very suitable for use as a final detection value, but is useful for use as a third value for determination of a difference error by the comparison means 45 as will be described later. It is.

  Specifically, in the case of the embodiment shown in FIG. 20, the comparison unit 45 is further provided with the auxiliary system detection value C in addition to the A system detection value A and the B system detection value B. In addition to the difference d between the value A and the B system detection value B, the difference dA (the absolute value of the difference between the detection value A and the detection value C) and the B system detection value between the A system detection value A and the auxiliary system detection value C The difference dB between B and the auxiliary system detection value C (absolute value of the difference between the detection value B and the detection value C) can be obtained. Therefore, when any of the three types of differences d, dA, and dB exceeds a predetermined allowable value T, an operation of outputting a difference error can be performed.

  In this way, if the operation of outputting the difference error by comparing the three detection values with each other is taken, more reliable abnormality notification is performed as compared with the operation of outputting the difference error by comparing the two detection values described above. It becomes possible.

  If the result of comparing these three detection values is used, the comparison means 45 can output a more appropriate value as the final detection value. For example, one of the A system detection value A and the B system detection value B is selectively output as the final detection value, and the difference dA and dB can be used as a selection criterion. it can. Specifically, the comparison unit 45 obtains the above-described three differences d, dA, and dB, and then outputs the A system detection value A as the final detection value when dA <dB, and when dA> dB. May output the B system detection value B as the final detection value.

  In other words, the detection value A or B that is closer to the third detection value C is output as the final detection value. When dA = dB, either detection value A or B may be used as the final detection value. If such a selection method is adopted, if there is a discrepancy between the detection values A and B, the one closer to the third detection value C is finally selected, and thus a more reliable value. Is output as the final detection value.

  Alternatively, after obtaining the above three differences d, dA, and dB, it is determined whether or not these exceed a predetermined allowable value T, and if two of the three exceed the predetermined allowable value T If it is, the detection value involved in the calculation of the two differences is estimated as a false detection value, and one of the two detection values excluding this false detection value (or based on these two detection values) An exception process may be performed in which a predetermined calculated value such as a calculated average value may be output as a final detection value.

  For example, in the above example, the difference d is the difference between the detection values A and B, the difference dA is the difference between the detection values A and C, and the difference dB is the difference between the detection values B and C. , DA, and dB, when only two of the differences d and dA exceed the allowable value T, the “difference between A and B” and the “difference between A and C” are large, and the “difference between B and C” "Is small. In this case, there is a high possibility that only the detected value A involved in the calculation of “difference between A and B” and “difference between A and C” indicates an abnormal value. Therefore, in this case, the detection value A is estimated as a false detection value, and one of the two detection values B and C excluding the false detection value A (or an average value calculated based on these two detection values) Etc.) is output as the final detection value, a more reliable value is output as the final detection value.

  As described above, in the embodiment shown in FIG. 19, that is, in the embodiment where n = 4 is set and the detection points P21 to P24 are defined at four locations, and the displacement in the vicinity of these detection points is detected using the capacitive element, Although the modified example which adds auxiliary system signal processing was demonstrated, of course, the modified example is not limited to the example which sets n = 4, and the example which uses a capacitive element as a detection element.

  In short, in the modified example in which the auxiliary system signal processing described here is added, in addition to the A system signal processing means 35A and the B system signal processing means 35B used in the basic embodiment described in §2, Based on both of the electrical detection signals detected by some or all of the A system detection elements and the electrical detection signals detected by some or all of the n B system detection elements. Auxiliary system signal processing means 35C for outputting an auxiliary system detection value C indicating a predetermined direction component of the external force applied to the force section is further provided, and the A system detection value A, the B system detection value B, and the auxiliary system are provided by the comparison means 45. The detection values C may be compared with each other to execute a difference error output process or an appropriate final detection value output process.

  Of course, such processing by the comparison means 45 may be performed by arithmetic processing using a digital circuit, or may be performed by signal processing using an analog circuit.

<3-3. Modification Example of Detection Structure>
In each of the embodiments described so far, as shown in FIG. 1, a detection structure formed by stacking the lower structure 100 and the upper structure 200 is used. For a plurality of n detection points defined in a predetermined place, the detection point is a type that detects the deflection or displacement of the vicinity thereof. However, the detection structure usable in the present invention is not limited to the type shown in FIG. In particular, the elastically deformable portion only needs to have a property of causing elastic deformation by the action of force, and does not necessarily need to be configured by the single diaphragm portion 120.

  For example, FIG. 3 shows a detection structure in which a lower structure 100 ′ and an upper structure 200 using four bridge portions 121 to 124 as elastic deformation portions instead of the diaphragm portion 120 are stacked. An example is shown. Of course, the force sensor according to the present invention may be configured using a detection structure of the type shown in FIG. In that case, what is necessary is just to replace the diaphragm part 120 in the above description with the four bridge parts 121-124. Since the deformation modes of the four bridge portions 121 to 124 are basically the same as the deformation modes of the diaphragm portion 120 shown in FIG. 2, the arrangement of each detection element and the processing content of each signal processing means are as follows. It may be the same as the embodiment described so far.

  Here, another modification of the structure for detection will be described with reference to FIG. The detection structure shown in FIG. 1 takes a form in which a plurality of n detection points are arranged on a single diaphragm portion 120 supported from the periphery by a support 110, whereas FIG. The detection structure 21 has a form in which a plurality of n detection points are dispersed and arranged on a plurality of m diaphragm portions supported from the periphery by a support.

  In the case of the modification shown here, the detection structure 10 is not completely multiplexed as in the example shown in FIG. However, since a plurality of m diaphragm portions are used, the diaphragm portions (elastic deformation portions) are multiplexed. Therefore, the reliability when the detection structure is damaged is improved as compared with the basic embodiments described so far.

  FIG. 21 (a) is a side sectional view of a detection structure according to this modification. Also in this example, the detection structure is composed of the lower structure 400 and the upper structure 500. Here, the upper structure 500 shown in FIG. 21 (a) has a disk-like shape, similar to the upper structure 200 used in the detection structure shown in FIG. 1 (a) described in §1-1. It has a force receiving portion 510 made of a substrate, and cylindrical force transmitting portions 521 to 524 connecting the lower surface of the force receiving portion 510 and the upper surface of the lower structure 400.

  In the case of the detection structure shown in FIG. 1 (a), the force transmission unit 220 is a single cylindrical member that connects the central portion of the lower surface of the force receiving portion 210 and the central portion 125 of the upper surface of the diaphragm portion 120. However, a total of four force transmission portions 521 to 524 are provided in the detection structure shown in FIG. In the modification shown in FIG. 21 (a), four localized diaphragm portions 421 to 424 are provided on the lower structure 400 side. This is for connecting the lower surface.

  The structure of the lower structure 400 is clearly shown in the bottom view of FIG. As shown in the figure, the lower structure 400 is a disk-like structure as a whole, and cylindrical grooves H1 to H4 are dug in four places on the lower surface thereof. The bottom of each of the grooves H1 to H4 (the upper layer portion of the lower structure 400) constitutes a thin disk-shaped diaphragm portion. Therefore, the lower structure 400 is formed with disk-shaped diaphragm portions at four locations. Here, each diaphragm part will be referred to as localized diaphragm parts 421-424. Of the lower structure 400, a portion excluding the localized diaphragm portions 421 to 424 becomes the support portion 410. Each of the disk-shaped localized diaphragm portions 421 to 424 is in a state where the periphery is supported by the thick support portion 410.

  Also in this modified example, the lower structure 400 and the upper structure 500 can be made of a general material such as metal or resin. Since the localized diaphragm parts 421 to 424 need to be elastically deformed by the action of an external force, the localized diaphragm parts 421 to 424 are set to have a thickness that exhibits flexibility when an external force to be detected acts. The other portions preferably act as rigid bodies as much as possible, so that a sufficient thickness is ensured.

  In FIG. 21 (b), the positions of the force transmission parts 521 to 524 connected to the upper surfaces of the localized diaphragm parts 421 to 424 are indicated by broken-line circles. As described above, the force transmission parts 521 to 524 are columnar members, and connect predetermined portions on the lower surface of the upper structure 500 to the upper surface centers of the localized diaphragm parts 421 to 424.

  The illustrated example is an example in which four sets of localized diaphragm portions 421 to 424 are provided, but the number of localized diaphragm portions may be arbitrary. Again, as shown in the figure, when the XYZ three-dimensional orthogonal coordinate system is defined with the origin O at the center position of the upper layer portion of the lower structure 400, the structural features of the detection structure according to the modification shown in FIG. Can be said as follows.

  First, the detection structure includes a lower structure 400 formed of a substrate extending along an XY plane (may be a plane parallel to the XY plane) with the Z axis as a central axis, and above the lower structure 400. The upper structure 500 is disposed. The substrate constituting the lower structure 400 is formed with thin plate-like localized diaphragm portions 421 to 424 extending in a direction along the XY plane (or a plane parallel to the XY plane) at a plurality of m locations. In the lower structure 400, these m sets of localized diaphragm portions 421 to 424 constitute an elastic deformation portion, and the other portions constitute a support portion 410.

  On the other hand, the upper structure 510 includes a force receiving portion 510 and m sets of force transmitting portions 521 to 524. Here, the force receiving portion 510 is configured by a plate-like substrate that is arranged at a predetermined distance above the substrate constituting the lower structure 400 so that the Z-axis becomes the central axis, and m sets of force The transmission parts 521 to 524 connect a predetermined location on the lower surface of the force receiving part 510 and the center of the upper surface of the m sets of diaphragm parts 421 to 424.

  Since the example of FIG. 21 is an example in which m = 4 is set, the substrate constituting the lower structure 400 has thin plate-like stations extending in four directions along the XY plane or a plane parallel to the XY plane. Existing diaphragm portions 421 to 424 are formed. Practically, it is preferable to set m = 4 as shown in this example and arrange the four sets of localized diaphragm portions 421 to 424 at the positions shown in the figure.

  As shown in FIG. 21 (a), the four sets of localized diaphragm portions 421 to 424 all have the same thickness, and their lower surfaces are included in a common plane. Here, if a common detection reference plane is set on this common plane and four detection points P21 to P24 are arranged on this detection reference plane (see FIG. 21B), these detection points P21 to P24 are arranged. This arrangement is equivalent to the embodiment shown in FIGS. The localized diaphragm portions 421 to 424 on the disk are arranged so that the detection points P21 to P24 are at the center positions.

  On the other hand, the upper structure 500 includes a force receiving portion 510 configured by a plate-like substrate disposed so that the Z axis is a central axis at a predetermined distance above the substrate constituting the lower structure 400, and 4 sets of force transmission parts 521-524 which connect the lower surface of force receiving part 510 and the upper surfaces of 4 sets of localized diaphragm parts 421-424.

  Of these four sets of force transmission units, the first force transmission unit 521 is located along a straight line parallel to the Z axis that intersects the positive X axis and the first position on the lower surface of the force receiving unit 510. The second force transmission unit 522 is connected to a predetermined position on the lower surface of the force receiving unit 510 and a second position along a straight line parallel to the Z axis that intersects the negative X axis. The third force transmission portion 523 is connected to a predetermined position on the lower surface of the force receiving portion 510 along a straight line parallel to the Z axis intersecting with the positive Y axis. The fourth localized force diaphragm 423 is connected to the center of the upper surface of the third localized diaphragm 423, and the fourth force transmission unit 524 is formed along a straight line parallel to the Z axis intersecting with the negative Y axis. The position and the center of the upper surface of the fourth localized diaphragm portion 424 are connected.

  After all, in the example of the detection structure shown in FIG. 21, m = 4 is set, and four sets of localized diaphragm portions 421 to 424 (elastic deformation portions) are provided in the lower structure 400, and n = 4 is set. Thus, it can be said that four detection points P21 to P24 are set on the elastic deformation portion. Since both m and n are set to 4, there is a one-to-one correspondence between the localized diaphragm portions and the detection points, and detection points P21 to P24 are defined at the center positions of the lower surfaces of the localized diaphragm portions 421 to 424, respectively. become. Moreover, each force transmission part 521-524 is connected above each detection point P21-P24.

  FIG. 22 (a) is a side sectional view showing a deformed state when force -Fz is applied to the force receiving portion 510 of the detection structure shown in FIG. 21, and FIG. 22 (b) is a moment. It is a sectional side view which shows a deformation | transformation state when + My acts. Since the external force is transmitted from the four force transmitting portions 521 to 524 to the center positions of the upper surfaces of the four localized diaphragm portions 421 to 424 with respect to the lower structure 400, the deformation mode can be changed for each local station. Although different for each existing diaphragm portion 421 to 424, there is no substitute for the fact that the predetermined direction component of the applied external force can be calculated by detecting the displacement in the vicinity of each detection point P21 to P24. In fact, when the deformation mode of the detection structure shown in FIG. 22 is compared with the deformation mode of the detection structure shown in FIG. 2, the characteristics of the deformation modes in the vicinity of the detection points P21 to P24 are similar. You will understand that.

  However, in the case of the detection structure shown in FIG. 22, since the force transmission parts 521 to 524 are connected above the detection points P21 to P24, the deflection is not caused in the immediate vicinity of the detection points P21 to P24. Almost does not occur. Therefore, here, an embodiment in which a capacitive element is used as the detection element will be described.

  FIG. 23 is a sectional side view (FIG. (A)) showing a force sensor according to an embodiment in which eight sets of capacitive elements are incorporated as detection elements in the detection structure shown in FIG. It is a figure (figure (b)). In order to arrange the fixed electrodes, four sets of electrode support substrates 601 to 604 are added below the four sets of localized diaphragm portions 421 to 424 at a predetermined distance. Each of these electrode support substrates 601 to 604 is a disk-shaped member whose periphery is fixed to the support portion 410. The eight sets of capacitive elements are configured by four sets of A-system capacitive elements C1A to C4A arranged on the outer side and four sets of B-system capacitive elements C1B to C4B arranged on the inner side.

  Also in FIG. 23, for convenience of explanation, an XYZ three-dimensional orthogonal coordinate system as illustrated is defined with the origin O at the center position of the upper layer portion of the lower structure 400. Then, as described above, the surface including the lower surface of each of the localized diaphragm portions 421 to 424 is set as a common detection reference surface, and the Z axis is centered on this detection reference surface as shown in FIG. If the detected reference circle G2 is drawn, all the detection points P21 to P24 are arranged on the detection reference circle G2.

  The illustrated example is an example in which the number m of localized diaphragm portions and the number n of detection points are both set to 4, and one detection point is defined at the center of the lower surface of each localized diaphragm portion. Here, if an X-axis projection image and a Y-axis projection image obtained by projecting the X-axis and the Y-axis onto the detection reference plane are defined, as shown in FIG. 23 (b), the first detection point P21 is The second detection point P22 is located at the intersection between the positive X-axis projection image and the detection reference circle G2, and the third detection point is located at the intersection between the negative X-axis projection image and the detection reference circle G2. P23 is located at the intersection of the positive Y-axis projection image and the detection reference circle G2, and the fourth detection point P24 is located at the intersection of the negative Y-axis projection image and the detection reference circle G2.

  For each of the detection points P21 to P24, if the side far from the Z axis is referred to as the outside, and the side close to the Z axis is referred to as the inside, the first A-system detection element is the first detection point P21. The displacement generated in the outer vicinity portion is electrically detected, and the first B-system detection element electrically detects the displacement generated in the inner vicinity portion of the first detection point P21. Similarly, the second A system detection element electrically detects the displacement generated in the vicinity of the outside of the second detection point P22, and the second B system detection element is the second The displacement generated in the vicinity of the inside of the detection point P22 is electrically detected.

  Further, the third A-line detection element electrically detects a displacement generated in the vicinity of the outside of the third detection point P23, and the third B-line detection element is the third detection point. The displacement generated in the vicinity portion inside the point P23 is electrically detected, and the fourth A-system detection element electrically detects the displacement generated in the vicinity portion outside the fourth detection point P24. The fourth B system detection element detects and electrically detects the displacement generated in the vicinity of the inside of the fourth detection point P24.

  In particular, the embodiment shown in FIG. 23 is an example in which a capacitive element is used as a detection element, and each capacitive element includes displacement electrodes E21A to E24A and E21B to E24B fixed to the lower surfaces of the localized diaphragm portions 421 to 424. The fixed electrodes E11A to E14A and E11B to E14B (electrodes disposed so as to face the displacement electrodes E21A to E24A and E21B to E24B) fixed to the upper surfaces of the electrode support substrates 601 to 604, and the displacement electrodes Has a function of outputting a displacement generated at a fixed position as a change in capacitance value. Such an arrangement of eight capacitive elements corresponds to the arrangement of eight capacitive elements in the force sensor shown in FIG.

  Specifically, the first A-system detection element is composed of a capacitive element C1A arranged outside the first detection point P21, and the first B-system detection element is the first detection point. Similarly, the second A-system detection element is composed of a capacitance element C2A disposed outside the second detection point P22, and the second B-system detection element is composed of the capacitance element C1B disposed inside P21. A system | strain detection element consists of capacitive element C2B arrange | positioned inside the 2nd detection point P22.

  The third A-system detection element is composed of a capacitive element C3A arranged outside the third detection point P23, and the third B-system detection element is inside the third detection point P23. In addition, the fourth A-line detection element is composed of the capacitive element C4A arranged outside the fourth detection point P24, and the fourth B-line detection element is , And the capacitive element C4B disposed inside the fourth detection point P24.

  Here, the feature of the deformation mode of the detection structure shown in FIG. 22 is substantially the same as the feature of the deformation mode of the detection structure shown in FIG. 2, and in the force sensor shown in FIG. Also, by using the A system signal processing means 35A and the B system signal processing means 35B shown in FIG. 17, the force component Fz in the Z-axis direction of the external force applied to the force receiving portion 510, the moment component Mx around the X-axis, The moment component My around the Y axis can be calculated.

That is, when the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B, respectively, using the same reference numerals, the A system signal processing means 35A has a predetermined sign. Using proportional coefficients K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
A system detection value indicating the three-axis components FzA, MxA, and MyA can be output by performing the following arithmetic processing or signal processing corresponding to the arithmetic processing.
Similarly, the B system signal processing means 35B uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
The B system detection value indicating the three-axis components FzB, MxB, and MyB can be output by performing the following arithmetic processing or signal processing corresponding to the arithmetic processing. The processing operation of the comparison means 45 is the same as that in the embodiments described so far.

<3-4. Combination of modifications>
So far, the basic embodiments of the present invention have been described in §2-1 to 2-5, and modifications thereof have been described in §3-1 to 3-3. Of course, these embodiments and modifications can be applied in combination with each other as necessary.

  The combination example shown in FIG. 24 is an example in which the modification example described in §3-1 is applied to the arrangement of the capacitive elements in the modification example (force sensor shown in FIG. 23) described in §3-3. That is, the difference between the force sensor shown in FIG. 23 and the force sensor shown in FIG. 24 is only the arrangement of eight capacitive elements.

  Specifically, in the force sensor shown in FIG. 23, similarly to the force sensor shown in FIG. 16, the A-line detection element is arranged in the vicinity of the outside of each detection point, and the B-line detection element is set to each detection point. 24, the force sensor shown in FIG. 24 sandwiches the X-axis or Y-axis in the same manner as the force sensor shown in FIG. The policy that the A system detection element and the B system detection element are arranged adjacent to each other is adopted.

  The force sensor shown in FIG. 23 and the force sensor shown in FIG. 24 are the same in terms of the detection structure used and the arrangement of n detection points. Both are examples in which the number m of the localized diaphragm portions and the number n of the detection points are set to 4, and one detection point P21 to P24 is respectively provided at the center of the bottom surface of the four sets of localized diaphragm portions 421 to 424. Is defined. In addition, since the detection element is configured by a capacitive element, there is no change in that four sets of electrode support substrates 601 to 604 are provided.

  Therefore, a common detection reference plane is set at the lower surface position of each of the localized diaphragm portions 421 to 424, and an X-axis projection image and a Y-axis projection image obtained by projecting the X axis and the Y axis onto the detection reference plane are defined. If the detection reference circle G2 centered on the Z-axis is drawn on the detection reference plane, the first detection point P21 is located at the intersection of the positive X-axis projection image and the detection reference circle G2, and the second Detection point P22 is located at the intersection of the negative X-axis projection image and the detection reference circle G2, and the third detection point P23 is located at the intersection of the positive Y-axis projection image and the detection reference circle G2. The fourth detection point P24 is located at the intersection of the negative Y-axis projection image and the detection reference circle G2.

  The first A-line detection element electrically detects a displacement of the first detection point P21 in the vicinity where the Y coordinate value is negative, and the first B-line detection element is The displacement generated in the vicinity of the first detection point P21 where the Y coordinate value is positive is electrically detected. Similarly, the second A system detection element electrically detects a displacement of the second detection point P22 in the vicinity where the Y coordinate value is negative, and the second B system detection element. Detects electrically the displacement generated in the vicinity of the second detection point P22 where the Y coordinate value is positive.

  The third A system detection element electrically detects a displacement of the third detection point P23 in the vicinity where the X coordinate value is negative, and the third B system detection element is The displacement generated in the vicinity of the third detection point P23 where the X coordinate value is positive is electrically detected. Further, the fourth A-line detection element electrically detects a displacement of the fourth detection point P24 in the vicinity where the X coordinate value is negative, and the fourth B-line detection element is The displacement generated in the vicinity of the fourth detection point P24 where the X coordinate value is positive is electrically detected.

  In particular, the embodiment shown in FIG. 24 is an example in which a capacitive element is used as a detection element, and each capacitive element includes displacement electrodes E21A to E24A and E21B to E24B fixed to the lower surfaces of the localized diaphragm portions 421 to 424. The fixed electrodes E11A to E14A and E11B to E14B (electrodes disposed so as to face the displacement electrodes E21A to E24A and E21B to E24B) fixed to the upper surfaces of the electrode support substrates 601 to 604, and the displacement electrodes Has a function of outputting a displacement generated at a fixed position as a change in capacitance value. Such an arrangement of the eight capacitive elements corresponds to the arrangement of the eight capacitive elements in the force sensor shown in FIG.

  Specifically, the first A-system detection element includes a capacitive element C1A arranged in the vicinity of the first detection point P21 where the Y coordinate value is negative, and the first B-system detection element. The element is composed of a capacitive element C1B arranged in the vicinity of the first detection point P21 where the Y coordinate value is positive. Similarly, the second A-system detection element is composed of a capacitive element C2A arranged in the vicinity of the second detection point P22 where the Y coordinate value is negative, and the second B-system detection element is The second detection point P22 includes a capacitive element C2B arranged in the vicinity of the Y coordinate value that is positive.

  The third A-system detection element is composed of a capacitive element C3A arranged in the vicinity of the third detection point P23 where the X coordinate value is negative, and the third B-system detection element is It consists of a capacitive element C3B arranged in the vicinity of the third detection point P23 where the X coordinate value is positive. Further, the fourth A-system detection element is composed of a capacitive element C4A arranged in the vicinity of the fourth detection point P24 where the X coordinate value is negative, and the fourth B-system detection element is The fourth detection point P24 includes a capacitive element C4B arranged in the vicinity where the X coordinate value is positive.

  Also in the force sensor shown in FIG. 24, the force component Fz in the Z-axis direction of the external force applied to the force receiving portion 510 is obtained by using the A system signal processing means 35A and the B system signal processing means 35B shown in FIG. The moment component Mx around the X axis and the moment component My around the Y axis can be calculated.

That is, when the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B, respectively, using the same reference numerals, the A system signal processing means 35A has a predetermined sign. Using proportional coefficients K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
A system detection value indicating the three-axis components FzA, MxA, and MyA can be output by performing the following arithmetic processing or signal processing corresponding to the arithmetic processing.

Similarly, the B system signal processing means 35B uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
The B system detection value indicating the three-axis components FzB, MxB, and MyB can be output by performing the following arithmetic processing or signal processing corresponding to the arithmetic processing. The processing operation of the comparison means 45 is the same as that in the embodiments described so far.

In the case of the force sensor shown in FIG. 24, as in the case of the force sensor shown in FIG. In that case, auxiliary system signal processing means 35C may be added in addition to A system signal processing means 35A and B system signal processing means 35B, as in the example shown in FIG. As described in § 3-2, this auxiliary system signal processing means 35C uses predetermined signed proportional coefficients K2C and K3C,
MxC = K2C × ((C1A + C2A) − (C1B + C2B))
MyC = K3C × ((C3B + C4B) − (C3A + C4A))
The auxiliary system detection value C indicating the moment component MxC around the X axis and the moment component MyC around the Y axis of the external force applied to the force receiving portion is output by performing the following calculation processing or signal processing corresponding to the calculation processing It is a component to do.

  As described above, if the auxiliary system detection value C is calculated, the comparison unit 45 further adds the A system detection value A and the auxiliary system in addition to the difference d between the A system detection value A and the B system detection value B. When the difference dA between the system detection value C and the difference dB between the B system detection value B and the auxiliary system detection value C is obtained, and any of the differences d, dA, dB exceeds a predetermined allowable value T, A differential error can be output. It is also possible to output a more appropriate value as the final detection value by using the differences d, dA, and dB. Details of such processing are as already described in §3-2.

  As described above, the force sensor according to the present invention is an example of a sensor that detects the three-axis components of the force component Fz in the Z-axis direction of the applied external force, the moment component Mx around the X axis, and the moment component My around the Y axis. As described above, of course, the present invention is not limited to such a force sensor for 3-axis detection. For example, a force sensor for 6-axis detection as disclosed in Patent Document 5 mentioned above. Alternatively, the present invention can also be applied to a torque sensor (one-axis detection force sensor that detects only the moment component Mz) as disclosed in the aforementioned Patent Document 6.

  Note that the detection structure having m sets of localized diaphragm portions shown in FIG. 21 can also be used as a detection structure of a force sensor for 6-axis detection disclosed in Patent Document 5 described above. . Therefore, in practice, it is possible to manufacture the force sensor shown in FIG. 23 or FIG. 24 using the manufacturing line of the force sensor for 6-axis detection.

10, 10A, 10B: detection structures 20, 20A, 20B: detection element 25A: A system detection element 25B: B system detection elements 30, 30A, 30B: signal processing means 35A: A system signal processing means 35B: B system Signal processing means 35C: auxiliary system signal processing means 40: comparison means 45: comparison means 100, 100 ': lower structure 110: support part 120: elastic deformation part (diaphragm part)
121-124: Elastic deformation part (bridge part)
125: central part 200: upper structure 210: force receiving part 220: force transmission part 300: electrode support substrate 400: lower structure 410: support parts 421 to 424: elastic deformation part (localized diaphragm part)
500: upper structure 510: force receiving portions 521 to 524: force transmitting portions 601 to 604: electrode support substrate A: A system detection value B: B system detection value C: auxiliary system detection values C1 to C4: capacitive element Capacitance value)
C1A to C4A: A-system capacitive element (capacitance value thereof)
C1B to C4B: B-system capacitive element (capacitance value thereof)
D1 to D4: detection elements (values of detection signals obtained therefrom)
D1A to D4A: A system detection element (value of detection signal obtained therefrom)
D1B to D4B: B system detection element (value of detection signal obtained therefrom)
d, dA, dB: Differences E11 to E14: Fixed electrodes E11A to E14A: A system fixed electrodes E11B to E14B: B system fixed electrodes E21 to E24: Displacement electrodes E21A to E24A: A system displacement electrodes E21B to E24B: B system displacement Electrode Fz: Force component in the Z-axis direction of external force FzA: A-system detected value of force component in the Z-axis direction of external force FzB: B-system detected value of force component in the Z-axis direction of external force G1, G2: Detection reference circle H, H1 to H4: Grooves K1 to K3: Proportional coefficient K1A to K3A: Proportional coefficient for system A K1B to K3B: Proportional coefficient for system B K2C, K3C: Proportional coefficient for auxiliary system Mx: Moment component MxA of external force around X axis: A system detected value MxB of the moment component of the external force around the X axis: B system detected value of the moment component of the external force around the X axis My: Moment component My of the external force around the Y axis : A system detected value MyB of moment component around Y axis of external force MyB: B system detected value of moment component around Y axis of external force O: Origin P1 to P4 of XYZ three-dimensional orthogonal coordinate system: Detection points P11 to P14: Detection Points P21 to P24: Detection points R1 to R4: Piezoresistive element (its resistance value)
R1A to R4A: System A piezoresistive elements R1B to R4B: System B piezoresistive elements S1 to S10: Steps SA of the flowchart: First sensor SB: Second sensor T: Allowable value VA: First sensor detection Value VB: Detected value of second sensor X: Coordinate axis of XYZ three-dimensional orthogonal coordinate system Y: Coordinate axis of XYZ three-dimensional orthogonal coordinate system Z: Coordinate axis of XYZ three-dimensional orthogonal coordinate system

(1) A first aspect of the present invention provides a force sensor for detecting a predetermined direction component of an applied external force,
An elastic deformation part that generates elastic deformation by the action of a force, a support part that supports the elastic deformation part, a force receiving part that receives an external force to be detected, and an external force applied to the force receiving part A structure for detection having a force transmitting portion for transmitting to a predetermined location;
N A-line detection elements that electrically detect bending or displacement generated in the first vicinity of each of a plurality of n detection points defined at predetermined positions of the elastic deformation portion;
n B-system detection elements that electrically detect deflection or displacement generated in a second vicinity different from the first vicinity of each of the n detection points ;
Provided,
For any i (1 ≦ i ≦ n), the i-th A-line detection element electrically detects the deflection or displacement of the first vicinity of the i-th detection point, and the i-th B The system detection element is configured to electrically detect deflection or displacement of the second vicinity of the i-th detection point,
Furthermore,
A system signal processing means for outputting an A system detection value indicating a predetermined direction component of the external force applied to the force receiving portion based on electrical detection signals detected by the n A system detection elements;
B system signal processing means for outputting a B system detection value indicating a predetermined direction component of the external force applied to the force receiving portion based on the electrical detection signals detected by the n B system detection elements;
The A system detection value and the B system detection value are compared, a difference d between them is obtained, and a predetermined calculation value calculated based on the A system detection value or the B system detection value or both is output as the final detection value. And a comparison means for outputting a difference error when the difference d exceeds a predetermined allowable value T;
Is provided.

Claims (32)

A force sensor for detecting a predetermined direction component of an applied external force,
An elastic deformation part that generates elastic deformation by the action of a force; a support part that supports the elastic deformation part; a force receiving part that receives an external force to be detected; and an external force applied to the force receiving part to the elastic deformation part A structure for detection having a force transmission part for transmitting to a predetermined position of
N A-line detection elements for electrically detecting deflection or displacement generated in the first vicinity of a plurality of n detection points defined at predetermined positions of the elastic deformation portion;
N number of B system detection elements for electrically detecting deflection or displacement generated in a second vicinity portion different from the first vicinity portion of the n detection points;
With
For any i (1 ≦ i ≦ n), the i-th A-line detection element electrically detects the deflection or displacement of the first vicinity of the i-th detection point, and the i-th B The system detection element electrically detects the deflection or displacement of the second vicinity of the i-th detection point,
Furthermore,
A system signal processing means for outputting an A system detection value indicating the predetermined direction component of the external force applied to the force receiving section based on an electrical detection signal detected by the n A system detection elements; ,
B system signal processing means for outputting a B system detection value indicating the predetermined direction component of the external force applied to the force receiving unit based on the electrical detection signals detected by the n B system detection elements; ,
The A system detection value and the B system detection value are compared, the difference d between them is obtained, and the predetermined detection value calculated based on the A system detection value or the B system detection value or both is finally detected A comparison means for outputting a difference error when the difference d exceeds a predetermined allowable value T.
A force sensor characterized by comprising: The force sensor according to claim 1,
When the XYZ three-dimensional orthogonal coordinate system is defined, the detection structure is
Consists of an elastically deformable portion constituted by a thin-plate-like diaphragm portion extending along an XY plane or a plane parallel to the XY plane with the Z axis as a central axis, and an annular structure that supports and fixes the periphery of the elastically deformable portion A lower structure having a support portion;
A force receiving portion constituted by a plate-like substrate disposed at a predetermined distance above the elastic deformation portion so that the Z-axis becomes a central axis, a lower surface center of the force receiving portion, and an upper surface of the elastic deformation portion An upper structure having a force transmission part connecting the center along the Z axis;
A force sensor characterized by comprising: The force sensor according to claim 1,
When the XYZ three-dimensional orthogonal coordinate system is defined, the detection structure is
An elastic deformation portion having a central portion located on the Z-axis, and a plurality of thin plate-like bridge portions extending radially from the central portion along a plane parallel to the XY plane or the XY plane, and the elastic deformation portion A lower structure having a support portion configured by an annular structure that supports and fixes the periphery of
A force receiving portion constituted by a plate-like substrate disposed at a predetermined distance above the elastically deforming portion so that the Z-axis becomes a central axis; a center of a lower surface of the force receiving portion; and an upper surface of the center portion A superconductor having a force transmission part connecting the Z-axis along the Z-axis,
A force sensor characterized by comprising: The force sensor according to claim 3, wherein
The elastically deforming portion includes a thin plate-like first bridge portion extending from the center portion toward the X-axis positive direction, a thin plate-like second bridge portion extending from the center portion toward the X-axis negative direction, and a Y-axis extending from the center portion. A force sensor comprising: a thin plate-like third bridge portion extending in a positive direction; and a thin plate-like fourth bridge portion extending in a Y-axis negative direction from a central portion. The force sensor according to claim 1,
When the XYZ three-dimensional orthogonal coordinate system is defined, the detection structure is configured by a substrate extending along the XY plane or a plane parallel to the XY plane with the Z axis as a central axis, and the lower structure An upper structure disposed above the body,
A thin plate-like localized diaphragm portion extending in a direction along an XY plane or a plane parallel to the XY plane is formed at a plurality of m locations on the substrate constituting the lower structure, and among the lower structures, These m sets of localized diaphragm portions constitute elastic deformation portions, and other portions constitute support portions,
The upper structure includes a force receiving portion configured by a plate-like substrate disposed at a predetermined distance above the substrate constituting the lower structure so that the Z axis is a central axis; and the force receiving portion A force sensor comprising: m sets of force transmitting portions that connect a predetermined portion of the lower surface of the set and the center of the upper surface of the m sets of diaphragm portions. The force sensor according to claim 5, wherein
By setting m = 4, a thin plate-like localized diaphragm portion extending in a direction along the XY plane or a plane parallel to the XY plane is formed at four locations on the substrate constituting the lower structure, The lower surface of each localized diaphragm is included in a common detection reference plane,
The upper structure includes a force receiving portion constituted by a plate-like substrate disposed at a predetermined distance above the substrate constituting the lower structure so that the Z axis is a central axis, and a lower surface of the force receiving portion And four sets of force transmission portions connecting the upper surfaces of the four sets of localized diaphragm portions,
Of the four sets of force transmission units, the first force transmission unit is arranged along a straight line parallel to the Z axis intersecting with the positive X axis and a predetermined position and a first localization on the lower surface of the force receiving unit. The second force transmission unit is connected to a center of the upper surface of the diaphragm unit, and the second force transmitting unit is located along a straight line parallel to the Z axis intersecting with the negative X axis and a predetermined position on the lower surface of the force receiving unit and the second localization. The third force transmitting portion connects the center of the upper surface of the diaphragm portion, and the third force transmitting portion is located along a straight line parallel to the Z axis intersecting with the positive Y axis and a predetermined position on the lower surface of the force receiving portion and the third localization The fourth force transmitting portion is connected to the center of the upper surface of the diaphragm portion, and the fourth position is located along a straight line parallel to the Z axis intersecting with the negative Y axis. A force sensor characterized by connecting the center of the upper surface of the diaphragm portion. The force sensor according to any one of claims 2 to 6,
When a detection reference plane is defined on the XY plane or a plane parallel to the XY plane, and a detection reference circle centered on the Z axis is drawn on this detection reference plane, all the n detection points are the detection reference circles. A force sensor arranged on the top. The force sensor according to claim 7, wherein
For each detection point, when the side far from the Z axis is called the outside and the side close to the Z axis is called the inside, for any i (1 ≦ i ≦ n),
The i-th A-system detection element electrically detects a deflection or a displacement in the vicinity of the outside of the i-th detection point,
A force sensor, wherein the i-th B system detection element electrically detects a deflection or a displacement of a portion near the inside of the i-th detection point. The force sensor according to any one of claims 1 to 8,
Based on both electrical detection signals detected by some or all of the n A-system detection elements and electrical detection signals detected by some or all of the n B-system detection elements An auxiliary system signal processing means for outputting an auxiliary system detection value indicating a predetermined direction component of the external force applied to the force receiving unit,
In addition to the difference d between the A system detection value and the B system detection value, the comparison means further includes a difference dA between the A system detection value and the auxiliary system detection value and a difference dB between the B system detection value and the auxiliary system detection value. The force sensor outputs a difference error when any of the differences d, dA, and dB exceeds a predetermined allowable value T. The force sensor according to claim 9, wherein
When dA <dB, the comparison means outputs the A system detection value as the final detection value, when dA> dB, the B system detection value is output as the final detection value, and when dA = dB, the A system detection value. Or the force sensor which outputs B system | strain detected value as a final detected value. The force sensor according to claim 9 or 10,
When two of the differences d, dA, and dB exceed a predetermined allowable value T, the comparison unit estimates a detection value that is involved in the calculation of the two differences as a false detection value. A force sensor characterized by performing an exceptional process for outputting a predetermined calculated value calculated based on one or both of two detected values excluding a detected value as a final detected value. The force sensor according to any one of claims 1 to 8,
The comparison means determines whether or not the A system detection value and the B system detection value are within a predetermined allowable range, and outputs a range-out error when exceeding the allowable range. Force sensor. The force sensor according to claim 12, wherein
The comparison means outputs the B system detection value as the final detection value when only the A system detection value exceeds the allowable range, and the A system detection value when only the B system detection value exceeds the allowable range. Is output as the final detection value, and when both the A system detection value and the B system detection value exceed the allowable range, a predetermined dummy value within the allowable range is output as the final detection value. Sense sensor. The force sensor according to any one of claims 1 to 8,
A force sensor, wherein the comparison means calculates an average value of the A system detection value and the B system detection value and outputs the average value as a final detection value. In the force sensor in any one of Claims 1-14,
For any i (1 ≦ i ≦ n)
The i-th A-system detection element is constituted by a piezoresistive element arranged in the first vicinity of the i-th detection point, and indicates a detection signal indicating a deflection occurring in the vicinity as a change in electric resistance value. Output
The i-th B system detection element is constituted by a piezoresistive element arranged in the second vicinity portion of the i-th detection point, and a detection signal indicating a deflection generated in the vicinity portion as a change in electric resistance value A force sensor. In the force sensor in any one of Claims 1-14,
For any i (1 ≦ i ≦ n)
The i-th A-system detection element is disposed so as to face the i-th A-system displacement electrode disposed in the first vicinity of the i-th detection point and the i-th A-system displacement electrode. Detecting the displacement generated in the first vicinity portion as a change in capacitance value, comprising an i-th A-system fixed electrode having an i-th A-system fixed electrode fixed to the support portion Output signal,
The i-th B system detection element is disposed so as to face the i-th B system displacement electrode disposed in the second vicinity of the i-th detection point and the i-th B system displacement electrode. Detected by a change in capacitance value, which is constituted by an i-th B-system capacitive element having an i-th B-system fixed electrode fixed to a support portion, and which shows a displacement generated in the second vicinity portion A force sensor that outputs a signal. The force sensor according to claim 2 or 4,
When the detection reference plane is defined on the upper surface or the lower surface of the diaphragm section or each bridge section, and the X-axis projection image and the Y-axis projection image obtained by projecting the X axis and the Y axis onto the detection reference plane are defined,
By setting n = 4, four detection points are defined on the detection reference plane. When a detection reference circle centered on the Z axis is drawn on the detection reference plane, the first detection point is drawn. The detection point is located at the intersection of the positive X-axis projection image and the detection reference circle, the second detection point is located at the intersection of the negative X-axis projection image and the detection reference circle, and the third The detection point is located at the intersection of the positive Y-axis projection image and the detection reference circle, the fourth detection point is located at the intersection of the negative Y-axis projection image and the detection reference circle,
For each detection point, when the side far from the Z axis is called the outside, the side near the Z axis is called the inside,
The first A-line detection element electrically detects a deflection or a displacement that has occurred in the vicinity of the outside of the first detection point, and the first B-line detection element is the first Electrically detects deflection or displacement that occurs in the vicinity of the inside of the detection point,
The second A-line detection element electrically detects a deflection or a displacement that has occurred in the vicinity of the outside of the second detection point, and the second B-line detection element is the second Electrically detects deflection or displacement that occurs in the vicinity of the inside of the detection point,
The third A-line detection element electrically detects deflection or displacement generated in the vicinity of the outside of the third detection point, and the third B-line detection element is the third Electrically detects deflection or displacement that occurs in the vicinity of the inside of the detection point,
The fourth A-line detection element electrically detects deflection or displacement generated in the vicinity of the outside of the fourth detection point, and the fourth B-line detection element is the fourth A force sensor characterized by electrically detecting a deflection or a displacement generated in a portion near the inside of a detection point. The force sensor according to claim 17,
Each detection element is composed of a piezoresistive element embedded in the upper surface or the lower surface of the diaphragm part or each bridge part, and each piezoresistive element outputs a deflection generated at the embedded position as a change in electric resistance value. Has function,
The first A-system detection element is composed of a piezoresistive element R1A arranged along the X-axis projection image outside the first detection point, and the first B-system detection element is the first It consists of a piezoresistive element R1B arranged along the X-axis projection image inside the detection point,
The second A-system detection element is composed of a piezoresistive element R2A arranged along the X-axis projection image outside the second detection point, and the second B-system detection element is the second It consists of a piezoresistive element R2B arranged along the X-axis projection image inside the detection point,
The third A-line detection element is composed of a piezoresistive element R3A arranged along the Y-axis projection image outside the third detection point, and the third B-line detection element is the third It consists of a piezoresistive element R3B arranged along the Y-axis projection image inside the detection point,
The fourth A-system detection element is composed of a piezoresistive element R4A arranged along the Y-axis projection image outside the fourth detection point, and the fourth B-system detection element is the fourth A force sensor comprising a piezoresistive element R4B arranged along a Y-axis projection image inside a detection point. The force sensor according to claim 18,
When the resistance values of the eight sets of piezoresistive elements R1A to R4A and R1B to R4B are expressed as R1A to R4A and R1B to R4B, respectively,
A system signal processing means uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (R1A + R2A + R3A + R4A)
MxA = K2A × (R3A-R4A)
MyA = K3A × (R1A-R2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are obtained. A system detection value is output,
The B system signal processing means uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (R1B + R2B + R3B + R4B)
MxB = K2B × (R3B-R4B)
MyB = K3B × (R1B-R2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X-axis, and the moment component MyB around the Y-axis are obtained. A force sensor that outputs a detected B system detection value. The force sensor according to claim 17,
Each detection element is constituted by a capacitive element having a displacement electrode fixed to the upper surface or the lower surface of the diaphragm portion or each bridge portion, and a fixed electrode fixed to the support portion so as to face the displacement electrode. Each capacitive element has a function of outputting a displacement generated at a position where the displacement electrode is fixed as a change in capacitance value,
The first A-system detection element is composed of a capacitive element C1A arranged outside the first detection point, and the first B-system detection element is arranged inside the first detection point. A capacitor element C1B,
The second A-line detection element is composed of a capacitive element C2A arranged outside the second detection point, and the second B-line detection element is arranged inside the second detection point. A capacitor element C2B,
The third A-line detection element is composed of a capacitive element C3A arranged outside the third detection point, and the third B-line detection element is arranged inside the third detection point. Capacitance element C3B,
The fourth A-system detection element is composed of a capacitive element C4A arranged outside the fourth detection point, and the fourth B-system detection element is arranged inside the fourth detection point. A force sensor comprising a capacitive element C4B. The force sensor according to claim 20,
When the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B using the same reference numerals,
A system signal processing means uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are obtained. A system detection value is output,
The B system signal processing means uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X-axis, and the moment component MyB around the Y-axis are obtained. A force sensor that outputs a detected B system detection value. The force sensor according to claim 2 or 4,
When the detection reference plane is defined on the upper surface or the lower surface of the diaphragm section or each bridge section, and the X-axis projection image and the Y-axis projection image obtained by projecting the X axis and the Y axis onto the detection reference plane are defined,
By setting n = 4, four detection points are defined on the detection reference plane. When a detection reference circle centered on the Z axis is drawn on the detection reference plane, the first detection point is drawn. The detection point is located at the intersection of the positive X-axis projection image and the detection reference circle, the second detection point is located at the intersection of the negative X-axis projection image and the detection reference circle, and the third The detection point is located at the intersection of the positive Y-axis projection image and the detection reference circle, the fourth detection point is located at the intersection of the negative Y-axis projection image and the detection reference circle,
The first A-line detection element electrically detects a displacement of the first detection point in the vicinity where the Y-coordinate value is negative, and the first B-line detection element is Electrically detecting a displacement of the first detection point in the vicinity where the Y coordinate value is positive;
The second A-system detection element electrically detects a displacement generated in the vicinity of the second detection point where the Y coordinate value is negative, and the second B-system detection element is Electrically detecting a displacement of the second detection point in the vicinity where the Y coordinate value is positive;
The third A system detection element electrically detects a displacement of the third detection point in the vicinity where the X coordinate value is negative, and the third B system detection element Electrically detecting a displacement of the third detection point in the vicinity where the X coordinate value is positive;
The fourth A-line detection element electrically detects a displacement generated in the vicinity of the fourth detection point where the X coordinate value is negative, and the fourth B-line detection element is A force sensor that electrically detects a displacement of a fourth detection point in the vicinity where the X coordinate value is positive. The force sensor according to claim 22, wherein
Each detection element is constituted by a capacitive element having a displacement electrode fixed to the upper surface or the lower surface of the diaphragm portion or each bridge portion, and a fixed electrode fixed to the support portion so as to face the displacement electrode. Each capacitive element has a function of outputting a displacement generated at a position where the displacement electrode is fixed as a change in capacitance value,
The first A-system detection element is composed of a capacitive element C1A arranged in the vicinity of the first detection point where the Y coordinate value is negative, and the first B-system detection element is the first detection point. Consisting of a capacitive element C1B arranged in the vicinity of the detection point at which the Y coordinate value is positive,
The second A-system detection element includes a capacitive element C2A arranged in the vicinity of the second detection point where the Y coordinate value is negative, and the second B-system detection element is the second detection point. Consisting of a capacitive element C2B arranged in the vicinity of the detection point of which the Y coordinate value is positive,
The third A-system detection element is composed of a capacitive element C3A arranged in the vicinity of the third detection point where the X coordinate value is negative, and the third B-system detection element is the third detection point. Consisting of a capacitive element C3B arranged in the vicinity of the detection point of which the X coordinate value is positive,
The fourth A-system detection element is composed of a capacitive element C4A arranged in the vicinity of the fourth detection point where the X coordinate value is negative, and the fourth B-system detection element is the fourth detection point. A force sensor comprising a capacitive element C4B arranged in the vicinity of the detection point of which the X coordinate value is positive. The force sensor according to claim 23, wherein
When the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B using the same reference numerals,
A system signal processing means uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are obtained. A system detection value is output,
The B system signal processing means uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X-axis, and the moment component MyB around the Y-axis are obtained. A force sensor that outputs a detected B system detection value. The force sensor according to claim 24, wherein
Using predetermined signed proportional coefficients K2C, K3C,
MxC = K2C × ((C1A + C2A) − (C1B + C2B))
MyC = K3C × ((C3B + C4B) − (C3A + C4A))
The auxiliary system detection value indicating the moment component MxC around the X-axis and the moment component MyC around the Y-axis of the external force applied to the force receiving portion is output by performing the following computation processing or signal processing corresponding to the computation processing. It further has auxiliary system signal processing means,
In addition to the difference d between the A system detection value and the B system detection value, the comparison means further includes a difference dA between the A system detection value and the auxiliary system detection value and a difference dB between the B system detection value and the auxiliary system detection value. The force sensor outputs a difference error when any of the differences d, dA, and dB exceeds a predetermined allowable value T. The force sensor according to claim 6, wherein
When an X-axis projection image and a Y-axis projection image obtained by projecting the X axis and the Y axis onto the detection reference plane are defined, and a detection reference circle centered on the Z axis is drawn on the detection reference plane,
By setting n = 4, one detection point is defined in the center of the lower surface of each localized diaphragm portion, and the first detection point is the intersection of the positive X-axis projection image and the detection reference circle. The second detection point is located at the intersection of the negative X-axis projection image and the detection reference circle, and the third detection point is at the intersection of the positive Y-axis projection image and the detection reference circle. And the fourth detection point is located at the intersection of the negative Y-axis projection image and the detection reference circle,
For each detection point, when the side far from the Z axis is called the outside, the side near the Z axis is called the inside,
The first A-line detection element electrically detects a displacement generated in the vicinity of the outside of the first detection point, and the first B-line detection element is the first detection point. Detect the displacement generated in the vicinity of the inside of the
The second A-line detection element electrically detects a displacement generated in the vicinity of the outside of the second detection point, and the second B-line detection element is the second detection point. Detect the displacement generated in the vicinity of the inside of the
The third A-line detection element electrically detects a displacement that has occurred in the vicinity of the outside of the third detection point, and the third B-line detection element is the third detection point. Detect the displacement generated in the vicinity of the inside of the
The fourth A-line detection element electrically detects a displacement generated in the vicinity of the outside of the fourth detection point, and the fourth B-line detection element is the fourth detection point. A force sensor characterized by electrically detecting a displacement generated in the vicinity of the inner side of the head. The force sensor according to claim 26, wherein
Each detection element is composed of a capacitive element having a displacement electrode fixed to the lower surface of each localized diaphragm portion and a fixed electrode fixed to the support portion so as to face the displacement electrode. , Having a function of outputting the displacement generated at the position where the displacement electrode is fixed as a change in capacitance value,
The first A-system detection element is composed of a capacitive element C1A arranged outside the first detection point, and the first B-system detection element is arranged inside the first detection point. A capacitor element C1B,
The second A-line detection element is composed of a capacitive element C2A arranged outside the second detection point, and the second B-line detection element is arranged inside the second detection point. A capacitor element C2B,
The third A-line detection element is composed of a capacitive element C3A arranged outside the third detection point, and the third B-line detection element is arranged inside the third detection point. Capacitance element C3B,
The fourth A-system detection element is composed of a capacitive element C4A arranged outside the fourth detection point, and the fourth B-system detection element is arranged inside the fourth detection point. A force sensor comprising a capacitive element C4B. The force sensor according to claim 27, wherein
When the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B using the same reference numerals,
A system signal processing means uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are obtained. A system detection value is output,
The B system signal processing means uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X-axis, and the moment component MyB around the Y-axis are obtained. A force sensor that outputs a detected B system detection value. The force sensor according to claim 6, wherein
When an X-axis projection image and a Y-axis projection image obtained by projecting the X axis and the Y axis onto the detection reference plane are defined, and a detection reference circle centered on the Z axis is drawn on the detection reference plane,
By setting n = 4, one detection point is defined in the center of the lower surface of each localized diaphragm portion, and the first detection point is the intersection of the positive X-axis projection image and the detection reference circle. The second detection point is located at the intersection of the negative X-axis projection image and the detection reference circle, and the third detection point is at the intersection of the positive Y-axis projection image and the detection reference circle. And the fourth detection point is located at the intersection of the negative Y-axis projection image and the detection reference circle,
The first A-line detection element electrically detects a displacement of the first detection point in the vicinity where the Y-coordinate value is negative, and the first B-line detection element is Electrically detecting a displacement of the first detection point in the vicinity where the Y coordinate value is positive;
The second A-system detection element electrically detects a displacement generated in the vicinity of the second detection point where the Y coordinate value is negative, and the second B-system detection element is Electrically detecting a displacement of the second detection point in the vicinity where the Y coordinate value is positive;
The third A system detection element electrically detects a displacement of the third detection point in the vicinity where the X coordinate value is negative, and the third B system detection element Electrically detecting a displacement of the third detection point in the vicinity where the X coordinate value is positive;
The fourth A-line detection element electrically detects a displacement generated in the vicinity of the fourth detection point where the X coordinate value is negative, and the fourth B-line detection element is A force sensor that electrically detects a displacement of a fourth detection point in the vicinity where the X coordinate value is positive. The force sensor according to claim 29,
Each detection element is composed of a capacitive element having a displacement electrode fixed to the lower surface of each localized diaphragm portion and a fixed electrode fixed to the support portion so as to face the displacement electrode. , Having a function of outputting the displacement generated at the position where the displacement electrode is fixed as a change in capacitance value,
The first A-system detection element is composed of a capacitive element C1A arranged in the vicinity of the first detection point where the Y coordinate value is negative, and the first B-system detection element is the first detection point. Consisting of a capacitive element C1B arranged in the vicinity of the detection point at which the Y coordinate value is positive,
The second A-system detection element includes a capacitive element C2A arranged in the vicinity of the second detection point where the Y coordinate value is negative, and the second B-system detection element is the second detection point. Consisting of a capacitive element C2B arranged in the vicinity of the detection point of which the Y coordinate value is positive,
The third A-system detection element is composed of a capacitive element C3A arranged in the vicinity of the third detection point where the X coordinate value is negative, and the third B-system detection element is the third detection point. Consisting of a capacitive element C3B arranged in the vicinity of the detection point of which the X coordinate value is positive,
The fourth A-system detection element is composed of a capacitive element C4A arranged in the vicinity of the fourth detection point where the X coordinate value is negative, and the fourth B-system detection element is the fourth detection point. A force sensor comprising a capacitive element C4B arranged in the vicinity of the detection point of which the X coordinate value is positive. The force sensor according to claim 30, wherein
When the capacitance values of the eight sets of capacitive elements C1A to C4A and C1B to C4B are expressed as C1A to C4A and C1B to C4B using the same reference numerals,
A system signal processing means uses a predetermined signed proportional coefficient K1A, K2A, K3A,
FzA = K1A × (C1A + C2A + C3A + C4A)
MxA = K2A × (C3A-C4A)
MyA = K3A × (C1A-C2A)
Or a signal process corresponding to the calculation process, the force component FzA in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxA around the X axis, and the moment component MyA around the Y axis are obtained. A system detection value is output,
The B system signal processing means uses a predetermined signed proportional coefficient K1B, K2B, K3B,
FzB = K1B × (C1B + C2B + C3B + C4B)
MxB = K2B × (C3B-C4B)
MyB = K3B × (C1B-C2B)
Or a signal process corresponding to the calculation process, the force component FzB in the Z-axis direction of the external force applied to the force receiving portion, the moment component MxB around the X-axis, and the moment component MyB around the Y-axis are obtained. A force sensor that outputs a detected B system detection value. The force sensor according to claim 31, wherein
Using predetermined signed proportional coefficients K2C, K3C,
MxC = K2C × ((C1A + C2A) − (C1B + C2B))
MyC = K3C × ((C3B + C4B) − (C3A + C4A))
The auxiliary system detection value indicating the moment component MxC around the X-axis and the moment component MyC around the Y-axis of the external force applied to the force receiving portion is output by performing the following computation processing or signal processing corresponding to the computation processing. It further has auxiliary system signal processing means,
In addition to the difference d between the A system detection value and the B system detection value, the comparison means further includes a difference dA between the A system detection value and the auxiliary system detection value and a difference dB between the B system detection value and the auxiliary system detection value. The force sensor outputs a difference error when any of the differences d, dA, and dB exceeds a predetermined allowable value T.

Images