JP2014119347A - Force sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a three-axis force and a three-axis moment, while achieving the miniaturization and the cost down.SOLUTION: The inside structural body 200 composed of a triangle pole is arranged at a position of an original point Q of an αβγ coordinate system, and a cylindrical outside structural body 100 which is outside the inside structure body 200, and further, a cylindrical outer shell structural body 300 which is outside the outside structural body 100 are arranged. The inside structural body 200 and the outer shell structural body 300 are connected, and basic sensors S1, S2, S3 are connected between the inside structural body 200 and the outside structure body 100. The outside structural body 100 is fixed on a pedestal, and when an outside force is acted on the outer shell structure body 300, the inside structural body 200 is made to operate by a relative displacement, and a distortion is generated in each basic sensor. Each basic sensor is defined with a separate XYZ coordinate system, respectively, and moments Mx, My around an X axis, a Y axis are detected based on the generated distortions. Forces Fα, Fβ, Fγ in each coordinate axis direction of the αβγ coordinate system and moments Mα, Mβ, Mγ around each coordinate axis can be obtained by the calculation based on the detection values Mx, My of each basic sensor.

Description

  The present invention relates to a force sensor, and more particularly to a force sensor that detects a force component in an arbitrary axis direction or a moment component around an arbitrary axis in a three-dimensional orthogonal coordinate system.

  In various industrial machines including robots, force sensors that detect forces acting on the joints between arms are used. In particular, in the case of an industrial machine driven by computer control, it is important to detect the force acting on each part separately for a force component in a predetermined axis direction and a moment component around the predetermined axis in a three-dimensional coordinate system.

  As a sensor having a function of independently detecting a three-dimensional force component in each axial direction and a moment component around each axis as described above, for example, Patent Document 1 listed below discloses a piezoresistor formed on a semiconductor substrate. A force sensor using an element is disclosed. In this force sensor, a semiconductor substrate is bonded to a strain generating body in which mechanical bending occurs due to the action of a force to be detected, and a change in the resistance value of a piezoresistive element formed on the semiconductor substrate is detected. The applied force is detected. Patent Document 2 discloses a force sensor that can further improve the technique disclosed in Patent Document 1, simplify the structure, and reduce costs.

  On the other hand, Patent Document 3 uses a structure in which four struts are passed between two parallel substrates, and detects the displacement state of each strut using a capacitive element. A 6-axis type force sensor capable of independently detecting a force component in the coordinate axis direction and a moment component around each coordinate axis is disclosed.

JP-A 63-266325 Japanese Patent No. 4987162 JP 2004-325367 A

  In recent years, the use of force sensors has expanded to various fields, and it is possible to detect force components in the direction of arbitrary coordinate axes and moment components around arbitrary coordinate axes according to individual applications, and to reduce size and cost. There is a demand for a force sensor that can achieve this. The force sensors disclosed in the above-mentioned Patent Documents 1 and 2 have a relatively simple structure, so that the advantage of miniaturization and cost reduction can be obtained, but the force component in the specific coordinate axis direction and the specific coordinate axis Since only the moment component can be detected, usable applications are limited.

  On the other hand, since the force sensor disclosed in Patent Document 3 is a 6-axis sensor, a force component in an arbitrary coordinate axis direction of a three-dimensional coordinate system and a moment component around an arbitrary coordinate axis are independently obtained. It has the advantage that it can be detected. However, the structure is complicated and it is difficult to reduce the size and cost.

  Therefore, the present invention can detect a force component in an arbitrary coordinate axis direction and a moment component around an arbitrary coordinate axis as desired (if necessary, the force component in each coordinate axis direction of the three-dimensional coordinate system and the direction around each coordinate axis). It is an object of the present invention to provide a force sensor that can detect the six-axis component of the moment component) and that can be reduced in size and cost.

(1) A first aspect of the present invention is a force sensor,
An outer structure having a receiving space inside;
An inner structure at least partially housed in the housing space;
A plurality of n sets (where n ≧ 3) of basic sensors;
A calculation means for calculating based on the outputs of the n sets of basic sensors;
Provided,
Each of the n sets of basic sensors
A connection function for directly or indirectly connecting an outer connection point provided at a predetermined position of the outer structure and an inner connection point provided at a predetermined position of the inner structure;
A deformation function that elastically deforms so that the relative positional relationship between the outer connection point and the inner connection point changes based on an external force acting on the other of the outer connection point and the inner connection point, and
The origin O located on the connecting line connecting the outer connecting point and the inner connecting point, the Z axis arranged on the connecting line, the X axis orthogonal to the Z axis, and the Y axis orthogonal to both the Z axis and the X axis And a detection function for detecting at least one of the moment component Mx around the X axis and the moment component My around the Y axis of the external force when an XYZ three-dimensional orthogonal coordinate system having an axis is defined,
The calculation means performs a calculation using the detection values detected by each of the n sets of basic sensors, so that the force and / or moment applied to the other of the outer structure and the inner structure in a state where one is fixed. Is to be detected.

(2) According to a second aspect of the present invention, in the force sensor according to the first aspect described above,
The outer structure is configured by a cylindrical structure that accommodates all or part of the inner structure therein, and each basic sensor is connected to an outer connection point and an inner structure on the inner peripheral surface of the cylindrical structure. Are connected to the inner connection point on the outer peripheral surface.

(3) According to a third aspect of the present invention, in the force sensor according to the second aspect described above,
An outer shell structure provided on the outer side of the outer structure and made of a cylindrical structure; and
A connecting member for connecting the outer shell structure and the inner structure;
Is further provided.

(4) According to a fourth aspect of the present invention, in the force sensor according to the third aspect described above,
When the outer shell structure is arranged so that the central axis thereof is directed in the vertical direction, a connecting member is constituted by a plate-like member covering the upper opening, and the outer shell structure is formed around the lower surface of the plate-like member. Are joined, and the upper surface of the inner structure is connected to the center of the lower surface of the plate-like member.

(5) According to a fifth aspect of the present invention, in the force sensor according to the fourth aspect described above,
When the outer structure and the outer shell structure are constituted by a concentric cylindrical structure having a common axis as a central axis, and the displacement of the inner structure relative to the outer structure reaches a predetermined allowable range, the outer structure The interval between the outer structure and the outer shell structure is set to a predetermined value so that the outer peripheral surface of the structure is in contact with the inner peripheral surface of the outer shell structure, and further displacement is limited,
Each basic sensor can perform a normal detection function as long as the displacement of the inner structure relative to the outer structure is within the allowable range.

(6) According to a sixth aspect of the present invention, in the force sensor according to the fourth or fifth aspect described above,
The outer structure and the outer shell structure are constituted by a concentric cylindrical structure having a common axis as a central axis,
The inner peripheral surface of the outer shell structure is provided with a control projection directed inward, and the outer peripheral surface of the outer structure is provided with a control groove for accommodating the tip of the control projection. The tip of the control projection so that the tip of the control projection and the groove-forming surface of the control groove come into contact with each other and the displacement is further limited when the displacement of the inner structure relative to And the distance between the groove forming surface of the control groove is set to a predetermined value,
Each basic sensor can perform a normal detection function as long as the displacement of the inner structure relative to the outer structure is within the allowable range.

(7) A seventh aspect of the present invention is the force sensor according to the fourth or fifth aspect described above,
The outer structure and the outer shell structure are constituted by a concentric cylindrical structure having a common axis as a central axis,
A control projection directed outward is provided on the outer peripheral surface of the outer structure, and a control groove for receiving a tip portion of the control projection is provided on the inner peripheral surface of the outer shell structure. The tip of the control projection so that the tip of the control projection and the groove-forming surface of the control groove come into contact with each other and the displacement is further limited when the displacement of the inner structure relative to And the distance between the groove forming surface of the control groove is set to a predetermined value,
Each basic sensor can perform a normal detection function as long as the displacement of the inner structure relative to the outer structure is within the allowable range.

(8) The eighth aspect of the present invention is the force sensor according to the second to seventh aspects described above,
A bottom plate member that covers the lower opening of the outer structure when the outer structure is arranged so that the central axis thereof is directed in the vertical direction, and a circuit board fixed to the upper surface of the bottom plate member are further provided. The arithmetic means is constituted by an arithmetic circuit formed on the circuit board.

(9) According to a ninth aspect of the present invention, in the force sensor according to the second to eighth aspects described above,
Attach the basic sensor to the basic sensor mounting part that forms the vicinity of the outer connection point of the outer structure,
Around this basic sensor mounting part, a plurality of wall through slits that penetrate the wall of the outer structure are provided along the contour line, and a flexible beam is provided between adjacent wall through slits. The basic sensor mounting portion is supported by the beam portion from the periphery.

(10) According to a tenth aspect of the present invention, in the force sensor according to the ninth aspect described above,
The basic sensor mounting portion has a circular contour line, and four sets of arc-shaped wall through slits are provided along the contour, and the beam portions are arranged between the adjacent wall through slits. As a result, a total of four sets of beam portions are formed, and the basic sensor mounting portion is supported by the four sets of beam portions from the periphery.

(11) The eleventh aspect of the present invention is the force sensor according to the first to tenth aspects described above,
The inner structure is constituted by a columnar structure at least a part of which is accommodated in the outer structure, and each basic sensor is connected to an outer connection point on the inner peripheral surface of the outer structure and the columnar structure. Are connected to the inner connection point on the outer peripheral surface.

(12) According to a twelfth aspect of the present invention, in the force sensor according to the eleventh aspect described above,
The inner structure is constituted by a triangular prism having an equilateral triangular cross section,
An inner connection point is provided on each side surface of the triangular prism, and three sets of basic sensors each have a connecting function for connecting each inner connection point and the outer connection point provided at the opposite position of the outer structure. It is a thing.

(13) According to a thirteenth aspect of the present invention, in the force sensor according to the eleventh aspect described above,
The inner structure is constituted by a triangular pyramid having an equilateral triangular cross section,
An inner connection point is provided on each side of the triangular pyramid, and three sets of basic sensors have a connecting function to connect each inner connection point and the outer connection point provided at the opposite position of the outer structure. It is a thing.

(14) According to a fourteenth aspect of the present invention, in the force sensor according to the eleventh aspect described above,
The inner structure is constituted by a square column having a square cross section,
An inner connection point is provided on each side surface of the quadrangular prism, and four sets of basic sensors have a connecting function to connect each inner connection point and the outer connection point provided at the opposite position of the outer structure. It is a thing.

(15) According to a fifteenth aspect of the present invention, in the force sensor according to the eleventh aspect described above,
The inner structure is constituted by a square pyramid with a square cross section,
An inner connection point is provided on each side surface of the quadrangular pyramid, and four sets of basic sensors have a connecting function for connecting each inner connection point and the outer connection point provided at the opposite position of the outer structure. It is a thing.

(16) According to a sixteenth aspect of the present invention, in the force sensor according to the above eleventh to fifteenth aspects,
Each basic sensor is arranged such that the connecting line connecting the outer connection point and the inner connection point is orthogonal to the outer surface of the columnar structure constituting the inner structure.

(17) According to a seventeenth aspect of the present invention, in the force sensor according to the first aspect described above,
Each of the outer structure and the inner structure is constituted by a cylindrical structure,
A plurality of n straight lines penetrating the first side wall of the outer structure, the first side wall of the inner structure, the second side wall of the inner structure, and the second side wall of the outer structure are defined. When defining straight lines as reference lines corresponding to n sets of basic sensors,
Insertion holes are respectively formed in the first side walls through which the reference lines of the inner structure pass,
Each basic sensor has an outer connection point provided on the inner peripheral surface of the first side wall of the outer structure through which the corresponding reference line passes, and an inner side of the second side wall of the inner structure through which the corresponding reference line passes. It has a connecting function of connecting an inner connection point provided on the peripheral surface through an insertion hole formed in the first side wall of the inner structure through which the corresponding reference line passes.

(18) According to an eighteenth aspect of the present invention, in the force sensor according to the seventeenth aspect described above,
A top plate member is further provided to cover the upper opening when the outer structure is arranged so that its central axis is directed in the vertical direction.

(19) According to a nineteenth aspect of the present invention, in the force sensor according to the eighteenth aspect described above,
When the outer structure and the inner structure are constituted by a concentric cylindrical structure having a common axis as a central axis, and the displacement of the outer structure with respect to the inner structure reaches a predetermined allowable range, the inner structure The outer peripheral surface of the body and the inner peripheral surface of the outer structure are in contact with each other, and the distance between the inner structure and the outer structure is set to a predetermined value so that further displacement is limited,
Each basic sensor can perform a normal detection function as long as the displacement of the outer structure relative to the inner structure is within the allowable range.

(20) According to a twentieth aspect of the present invention, in the force sensor according to the eighteenth or nineteenth aspect described above,
When the outer structure and the inner structure are constituted by a concentric cylindrical structure having a common axis as a central axis, and the displacement of the outer structure with respect to the inner structure reaches a predetermined allowable range, the inner structure The interval between the basic sensor part and the insertion hole is set to a predetermined value so that the insertion hole formed in the body comes into contact with a part of the basic sensor that passes through the insertion hole and further displacement is limited. ,
Each basic sensor can perform a normal detection function as long as the displacement of the outer structure relative to the inner structure is within the allowable range.

(21) According to a twenty-first aspect of the present invention, in the force sensor according to the nineteenth or twentieth aspect described above,
Each basic sensor is arranged such that the connecting line connecting the outer connection point and the inner connection point is orthogonal to the common central axis of the outer structure and the inner structure.

(22) According to a twenty-second aspect of the present invention, in the force sensor according to the seventeenth to twenty-first aspects described above,
The vicinity of the intersection with the reference line of the first side wall of the outer structure constitutes a diaphragm portion that is thinner than the other portions, and one end of the basic sensor is joined to this diaphragm portion. Is.

(23) According to a twenty-third aspect of the present invention, in the force sensor according to the seventeenth to twenty-second aspects described above,
A plurality of n sets of basic sensors each have a hook-shaped portion for performing a connection function, and at least some of the basic sensors can avoid contact with the hook-shaped portions of other basic sensors. It is made to curve like this.

(24) According to a twenty-fourth aspect of the present invention, in the force sensor according to the seventeenth to twenty-third aspects described above,
A bottom plate member that covers the lower opening of the inner structure when the inner structure is arranged so that the central axis thereof is directed in the vertical direction, and a circuit board fixed to the upper surface of the bottom plate member are further provided. The arithmetic means is constituted by an arithmetic circuit formed on a circuit board.

(25) According to a twenty-fifth aspect of the present invention, in the force sensor according to the seventeenth to twenty-fourth aspects described above,
An outer shell structure provided on the outer side of the outer structure and made of a cylindrical structure; and
A connecting member that connects the outer structure and the outer shell structure;
Is further provided.

(26) According to a twenty-sixth aspect of the present invention, in the force sensor according to the first to eleventh and seventeenth to twenty-fifth aspects described above,
When defining an αβγ three-dimensional orthogonal coordinate system having an α axis, a β axis, and a γ axis orthogonal to each other at the origin Q defined inside the inner structure,
The Z-axis of the XYZ three-dimensional orthogonal coordinate system defined for each basic sensor is defined in the direction passing through the origin Q,
The computing means acted about the force component Fα acting in the α-axis direction, the force component Fβ acting in the β-axis direction, the force component Fγ acting in the γ-axis direction, the moment component Mα acting around the α-axis, and the β-axis. At least one component of the moment component Mγ and the moment component Mγ acting around the γ-axis is 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 X axis and each Z axis defined for each basic sensor are axes included in the αβ plane, and each Y axis defined for each basic sensor is defined to be parallel to the γ axis. Is.

(28) According to a twenty-eighth aspect of the present invention, in the force sensor according to the twenty-seventh aspect described above,
Three sets of basic sensors are arranged so that each Z-axis forms 120 ° with respect to each other.

(29) According to a twenty-ninth aspect of the present invention, in the force sensor according to the twenty-eighth aspect described above,
On the αβ plane, an azimuth angle is defined with the α axis direction being 0 ° and the β axis direction being 90 °. Further, the δ axis facing the azimuth angle 210 ° direction and the azimuth angle 330 ° direction When we define the facing ε axis,
The Z-axis positive direction defined for the first basic sensor matches the β-axis negative direction, the Z-axis positive direction defined for the second basic sensor matches the δ-axis negative direction, and the third basic sensor Three basic sensors having the same detection sensitivity are arranged so that the defined Z-axis positive direction coincides with the ε-axis negative direction,
The computing means Mx1 moment component around the X axis detected by the first basic sensor, My1 moment component around the Y axis detected by the first basic sensor, and around the X axis detected by the second basic sensor. Moment component Mx2, moment component around Y axis detected by second basic sensor My2, moment component around X axis detected by third basic sensor Mx3, moment component around Y axis detected by third basic sensor Fα = K11 (−My1 + 1/2 · My2 + 1/2 · My3) using predetermined coefficient values K11, K12, K13, K14, K15, and K16, where My3 is the moment component
Fβ = K12 (−√3 / 2 · My2 + √3 / 2 · My3)
Fγ = K13 (Mx1 + Mx2 + Mx3)
Mα = K14 (Mx1-1 / Mx2-1 / Mx3)
Mβ = K15 (√3 / 2 · Mx2−√3 / 2 · Mx3)
Mγ = K16 (My1 + My2 + My3)
6 components of force components Fα, Fβ, Fγ and moment components Mα, Mβ, Mγ are detected by performing the following calculation.

(30) According to a thirtieth aspect of the present invention, in the force sensor according to the twenty-seventh aspect,
Four sets of basic sensors are arranged so that each Z-axis forms 90 ° with respect to each other.

(31) According to a thirty-first aspect of the present invention, in the force sensor according to the thirtieth aspect described above,
The Z-axis positive direction defined for the first basic sensor matches the β-axis negative direction, the Z-axis positive direction defined for the second basic sensor matches the α-axis positive direction, and the third basic sensor Four sets of basic sensors having the same detection sensitivity so that the defined Z-axis positive direction matches the β-axis positive direction and the Z-axis positive direction defined for the fourth basic sensor matches the α-axis negative direction Is placed,
The computing means Mx1 moment component around the X axis detected by the first basic sensor, My1 moment component around the Y axis detected by the first basic sensor, and around the X axis detected by the second basic sensor. Moment component Mx2, moment component around Y axis detected by second basic sensor My2, moment component around X axis detected by third basic sensor Mx3, moment component around Y axis detected by third basic sensor , The moment component around the X axis detected by the fourth basic sensor is Mx4, and the moment component around the Y axis detected by the fourth basic sensor is My4. Using K22, K23, K24, K25, K26 Fα = K21 (−My1 + My3)
Fβ = K22 (−My2 + My4)
Fγ = K23 (Mx1 + Mx2 + Mx3 + Mx4)
Mα = K24 (Mx1-Mx3)
Mβ = K25 (Mx2-Mx4)
Mγ = K26 (My1 + My2 + My3 + My4)
6 components of force components Fα, Fβ, Fγ and moment components Mα, Mβ, Mγ are detected by performing the following calculation.

(32) A thirty-second aspect of the present invention provides the force sensor according to the twenty-sixth aspect,
Each Z axis defined for each basic sensor points in a direction that makes an inclination angle θ with respect to the αβ plane, and each Y axis that is defined for each basic sensor indicates a direction that makes an inclination angle θ with respect to the γ axis. Each basic sensor is arranged so as to face.

(33) According to a thirty-third aspect of the present invention, in the force sensor according to the first to thirty-second aspects described above,
Each basic sensor, a force receiving body that receives an applied external force, a strain generating body having a diaphragm portion that is deformed based on the force received by the force receiving body, and a connection member that connects the force receiving body and the diaphragm portion The detection element detects the distortion of the diaphragm portion, and the detection circuit outputs at least one of the moment components Mx and My as an electric signal based on the detection result of the detection element.

(34) According to a thirty-fourth aspect of the present invention, in the force sensor according to the thirty-third aspect described above,
As the detecting element, a piezoresistive element that detects the distortion of the diaphragm portion as a change in resistance value is used.

(35) According to a thirty-fifth aspect of the present invention, in the force sensor according to the thirty-fourth aspect described above,
The strain body is constituted by a plate-like member having an upper surface and a lower surface parallel to the XY plane, and a detection groove defined in the central portion of the upper surface of the strain body has a detection groove toward the lower surface side. The diaphragm portion is formed by the bottom portion of the detection groove, the side wall portion is formed around the detection groove, and the lower surface of the diaphragm portion and the lower surface of the side wall portion are located on the same plane,
The force receiving body is arranged below the strain body at a predetermined interval,
The connecting member is constituted by a columnar member arranged on the Z axis, the upper end thereof is connected to the lower surface center portion of the diaphragm portion, and the lower end thereof is connected to the upper surface center portion of the force receiving body,
The strain detection board further includes a strain detection board disposed at the position of the origin O of the XYZ three-dimensional orthogonal coordinate system and joined to the diaphragm portion. The strain detection board has a top surface and a bottom face parallel to the XY plane, and a detection groove. Is joined to the bottom surface of the diaphragm so that the stress caused by the deformation of the diaphragm is transmitted,
The piezoresistive element is formed at a predetermined location on the upper surface of the strain detection substrate,
The detection circuit outputs an electric signal indicating the moment component Mx and / or My based on the change in the electric resistance of the piezoresistive element.

(36) The thirty-sixth aspect of the present invention is the force sensor according to the thirty-third aspect described above,
As the detection element, a capacitance element that detects the displacement of the diaphragm portion as a change in capacitance value is used.

  According to the force sensor of the present invention, the inner structure is accommodated in the outer structure, and the two are connected by a plurality of n sets of basic sensors (where n ≧ 3) and detected by each of the basic sensors. Since the calculation is performed on the moment component, the force component in the direction of the arbitrary coordinate axis and the moment component around the arbitrary coordinate axis can be detected as desired while reducing the size and cost by a relatively simple structure. Will be able to. Of course, if necessary, it is possible to realize a force sensor that detects the six-axis component of the force component in each coordinate axis direction of the three-dimensional coordinate system and the moment component around each coordinate axis.

It is the top view (upper figure (a)) and side view (lower figure (b)) of a basic structure about an example (example using a piezoresistive element) which can be used for a force sensor concerning the present invention. . 1 is a top view (upper view (a)) showing a state in which the cover 18 of the basic structure shown in FIG. 1 has been removed, and a side sectional view (lower view (b)) cut along the XZ plane (the hatching of the cover bonding portion 19 is shown in FIG. , Not a cross section, but a region). It is a bottom view of the basic structure shown in FIG. FIG. 4 is a bottom view showing a state where four screws N are inserted through the basic structure shown in FIG. 3. FIG. 2 is a top view (upper view (a)) showing a state in which the cover 18 of the basic structure shown in FIG. 1 is removed, and a side sectional view (lower view (b)) cut at the position of the cutting line WW. The hatching of the portion 19 does not indicate a cross section but indicates a region). It is a sectional side view in the XZ plane which shows a deformation | transformation state when the moment component + My around Y-axis acts on the basic structure shown in FIG. It is a sectional side view in the XZ plane which shows a deformation | transformation state when force component + Fz of a Z-axis direction acts on the basic structure shown in FIG. It is a top view which shows the example of arrangement | positioning of the piezoresistive element in the basic sensor shown in FIG. 1 (a hatching shows the formation area of a piezoresistive element, and does not show a cross section). It is a table | surface which shows the change of the resistance value of each piezoresistive element in the example of arrangement | positioning shown in FIG. FIG. 9 is a circuit diagram showing a detection circuit for detecting a moment component My around the Y axis in the arrangement example shown in FIG. 8. FIG. 9 is a circuit diagram showing a detection circuit for detecting a moment component Mx around the X axis in the arrangement example shown in FIG. 8. It is the cross-sectional view which cut | disconnected the force sensor which concerns on the 1st Embodiment of this invention by the (alpha) (beta) plane (it is a top view about basic sensors S1-S3). It is the longitudinal cross-sectional view which cut | disconnected the force sensor which concerns on the 1st Embodiment of this invention by (epsilon) plane (it is a side view about basic sensor S3). It is a cross-sectional view which shows the direction of the coordinate axis (X-axis, Y-axis, Z-axis) of basic sensor S1-S3 used as the component of the force sensor shown in FIG. FIG. 13 is a cross-sectional view showing detection operations of the basic sensors S1 to S3 when a positive force + Fα is applied to the inner structure 200 of the force sensor shown in FIG. 12. FIG. 13 is a cross-sectional view showing detection operations of the basic sensors S1 to S3 when a force + Fβ in the β-axis positive direction is applied to the inner structure 200 of the force sensor shown in FIG. 12. FIG. 13 is a cross-sectional view showing detection operations of the basic sensors S1 to S3 when a force + Fγ in the positive direction of the γ-axis acts on the inner structure 200 of the force sensor shown in FIG. 12. FIG. 13 is a cross-sectional view showing detection operations of the basic sensors S1 to S3 when a moment + Mα about the positive direction of the α-axis is applied to the inner structure 200 of the force sensor shown in FIG. 12. FIG. 13 is a cross-sectional view showing detection operations of the basic sensors S1 to S3 when a moment + Mβ around the β-axis positive direction is applied to the inner structure 200 of the force sensor shown in FIG. 12. FIG. 13 is a cross-sectional view showing detection operations of the basic sensors S1 to S3 when a moment + Mγ about the positive direction of the γ-axis acts on the inner structure 200 of the force sensor shown in FIG. 13 is a table showing detection values output from the basic sensors S1 to S3 when six-axis components of external force act on the inner structure 200 of the force sensor shown in FIG. It is a figure which shows the formula of the calculation performed in order to detect a 6-axis component with the force sensor shown in FIG. It is the longitudinal cross-sectional view which cut | disconnected the force sensor which concerns on the 2nd Embodiment of this invention by (epsilon) plane (it is a side view about basic sensor S3). It is the longitudinal cross-sectional view which cut | disconnected the force sensor which concerns on the 3rd Embodiment of this invention by (epsilon) γ plane (it is a side view about basic sensor S3). It is the cross-sectional view which cut | disconnected the force sensor which concerns on the 4th Embodiment of this invention by (alpha) (beta) plane (it is a top view about basic sensors S1'-S3 '). It is the longitudinal cross-sectional view which cut | disconnected the force sensor which concerns on the 4th Embodiment of this invention in (epsilon) plane (it is a side view about basic sensor S3 '). It is the longitudinal cross-sectional view which cut | disconnected the force sensor which concerns on the modification of the 4th Embodiment of this invention by (epsilon) γ plane (it is a side view about basic sensor S3 '). It is the cross-sectional view which cut | disconnected the force sensor which concerns on the modification of this invention by the (alpha) (beta) plane (it is a top view about basic sensors S1-S4). It is a figure which shows the type | formula of the calculation performed in order to detect a 6-axis component with the force sensor shown in FIG. It is a perspective view which shows the structure of the outer structure 100E of the force sensor which concerns on another modification of this invention (The attachment state of basic sensor S1-S3 is shown with the broken line). It is a side view which shows another example (example using a capacitive element) of the basic sensor which can be utilized for the force sensor which concerns on this invention. It is a top view of the strain body 70 in the basic sensor shown in FIG.

  Hereinafter, the present invention will be described based on the illustrated embodiments. The force sensor according to the present invention is an apparatus configured by combining three or more basic sensors. Therefore, for the sake of convenience, the configuration and operation of a specific example of the basic sensor will be described in §1 and §2, and embodiments of the force sensor configured using this basic sensor will be described in §3 and thereafter.

<<< §1. Specific configuration example of basic sensor >>>
Here, first, a specific configuration example of the basic sensor used as one part of the force sensor according to the present invention will be described. The basic sensor described here is a sensor disclosed in the above-mentioned Patent Document 2 (Japanese Patent No. 4987162), and details thereof are described in Patent Document 2. Therefore, in the following description, the structure and operation will be briefly described.

  FIG. 1 shows a top view (upper view (a)) and a side view (lower view (b)) of the basic structure constituting the basic sensor. As shown in the lower side view, main components of the basic structure are the strain body 10, the connection member 20, and the force receiving body 30.

  As shown in the top view in the upper part of FIG. 1, the strain body 10 is constituted by a plate-like member having an upper surface and a lower surface parallel to the XY plane. As shown by a broken line in the lower side view, a detection groove G1 is provided inside the strain body 10, and a diaphragm portion 11 is formed by the bottom of the detection groove G. On the other hand, a side wall 12 is formed around the detection groove G1. Further, a strain detection substrate 40 is disposed on the bottom surface of the detection groove G1 (the top surface of the diaphragm portion 11).

  Here, for convenience of explanation, an XYZ three-dimensional orthogonal coordinate system is defined by taking the origin O at the center position of the strain detection substrate 40 and taking the X, Y, and Z axes in the directions shown in the figure. That is, in the top view of the upper stage, the X axis is defined in the right direction, the Y axis is defined in the upward direction, and the Z axis is oriented in a direction perpendicular to the paper surface. In the lower side view, the X axis is defined in the right direction, the Z axis is defined in the upper direction, and the Y axis is oriented in a direction perpendicular to the paper surface.

  In the case of the example shown here, the force receiving body 30 is also configured by a plate-like member having an upper surface and a lower surface parallel to the XY plane. And as shown with a broken line in the figure, the detection groove | channel G2 is provided in the inside, and the diaphragm part 31 is formed of the bottom part of this detection groove | channel G. On the other hand, a side wall 32 is formed around the detection groove G2. In the case of the illustrated example, the strain body 10 and the force receiving body 30 are configured by disk-shaped members having the same diameter, and are arranged so that the Z axis is the central axis. The force receiving body 30 is completely overlapped with the strain body 10.

  The force receiving body 30 is arranged below the strain body 10 with a predetermined interval, and the two are connected by the connecting member 20. The connecting member 20 is constituted by a columnar member (in this example, a columnar member) arranged on the Z axis, and its upper end is connected to the center of the lower surface of the diaphragm portion 11 and its lower end is the diaphragm portion 31. Is connected to the central portion of the upper surface.

  In the case of the example shown here, the strain body 10, the connection member 20, and the force receiving body 30 are made of the same material (for example, a metal having a linear expansion coefficient close to that of a silicon substrate such as Kovar or 42-alloy, or stainless steel or aluminum). It is comprised by the integral structure which consists of a metal. Therefore, the connection part between the strain body 10 and the connection member 20 and the connection part between the connection member 20 and the force receiving body 30 are not joined by an adhesive or the like, but are constituted by a continuous structure made of the same material.

  The petal-like cover 18 depicted in the top view of FIG. 1 functions as a lid that covers the upper part of the detection groove G1. As will be described later, the planar shape of the detection groove G1 has a petal shape that is slightly smaller than the contour shape of the cover 18. The detection groove G1 drawn with a broken line in the lower side view indicates the contour position of the detection groove G1 when the strain body 10 is cut along the XZ plane. As shown in the upper part of FIG. 1, four screw holes 15 are formed in the side wall portion 12 of the strain body 10 (the screw holes are not shown in the lower side view). Further, the circuit board 50 protruding outward from the side wall portion 12 of the strain generating body 10 is a board for mounting the detection circuit, and one end thereof reaches the detection groove G1.

  The basic structure inside the basic sensor will be further clarified by referring to FIG. 2 shows a top view (upper view (a)) showing a state in which the cover 18 of the basic structure shown in FIG. 1 is removed, and a side sectional view (lower view (b)) cut along the XZ plane. Has been. Here, in the upper plan view of the upper stage, the hatched portion by the dots sandwiched between the petal-like contours f1 and f2 is an area of the cover adhesion portion 19 for adhering the lower surface peripheral portion of the cover 18 (Hatching is for indicating a region, not for a cross section).

  As shown in the side sectional view of the lower part of FIG. 2, the cover bonding portion 19 is a step portion formed at a position that is lowered from the upper surface of the strain body 10 by a dimension corresponding to the thickness of the cover 18. Further, the petal-like contour f2 shown in the upper part of FIG. 2 matches the contour shape of the cover 18 shown in FIG. Therefore, if the adhesive is applied to the portion of the cover bonding portion 19 shown hatched in the figure and the cover 18 is fitted to the stepped portion from above, the peripheral portion of the lower surface of the cover 18 is bonded and fixed to the cover bonding portion 19. can do.

  On the other hand, the inner contour f1 of the cover bonding portion 19 indicates the contour of the detection groove G1. That is, a detection area corresponding to the inside of the petal-like contour f1 is defined at the center of the upper surface of the strain body 10, and the detection area is directed toward the lower surface side of the strain body 10. A detection groove G1 having a uniform depth is formed. The side sectional view of the lower part of FIG. 2 shows a section obtained by cutting the basic structure along the XZ plane, so that only a part of the longitudinal section of the detection groove G1 appears, but the top view of FIG. As described above, the detection groove G1 has a petal-like planar shape. The depth of the detection groove G1 is uniform, and a petal-shaped diaphragm portion 11 having a uniform thickness is formed at the bottom of the detection groove G1. Since the diaphragm portion 11 is thin, the diaphragm portion 11 is bent (mechanically deformed) when subjected to the action of a force to be detected. As illustrated, the lower surface of the diaphragm portion 11 and the lower surface of the side wall portion 12 are located on the same plane.

  The strain detection substrate 40 is a square semiconductor substrate having an upper surface and a lower surface that are parallel to the XY plane, and is arranged so that the Z axis is the central axis. As shown in the top view in the upper part of FIG. 2, the petal-like planar shape of the detection groove G <b> 1 is a shape suitable for accommodating the square-shaped strain detection substrate 40. 2, the strain detection substrate 40 is joined to the bottom surface of the detection groove G1 (that is, the upper surface of the diaphragm portion 11) so that the stress generated by the deformation of the diaphragm portion 11 is transmitted. (Specifically, the strain detection substrate 40 is bonded to the upper surface of the diaphragm portion 11 by applying an adhesive on the entire lower surface).

  A piezoresistive element A is formed at a predetermined position on the upper surface of the strain detection substrate 40 (not shown in the lower side sectional view). In the example shown here, the strain detection substrate 40 is configured by a silicon substrate, and the piezoresistive element A can be configured as a region in which P-type or N-type impurities are implanted into the upper surface layer of the silicon substrate. In the example in the upper part of FIG. 2, eight sets of piezoresistive elements A are arranged in the immediate vicinity of the position of the connecting member 20 indicated by a broken line, but the number and arrangement of the piezoresistive elements are limited to this example. is not.

  In short, the strain detection substrate 40 used in this basic sensor has a top surface and a bottom surface that are parallel to the XY plane, and is joined to the bottom surface of the detection groove G1 so that stress generated by deformation of the diaphragm portion 11 is transmitted. Any device may be used as long as a piezoresistive element is formed at a predetermined position on the upper surface. On the circuit board 50, a detection circuit (not shown) that outputs an electric signal indicating the force received by the force receiving body 30 based on a change in the electric resistance of the piezoresistive element A is mounted.

  On the other hand, the force receiving body 30 is a component having substantially the same structure as the strain body 10. The strain body 10 is provided with a detection groove G1 on the upper surface side, whereas the force receiving body 30 is provided with a detection groove G2 on the lower surface side. Here, the planar shape of the detection groove G2 is circular. While the strain detection substrate 40 is disposed in the detection groove G1, such a component is not provided in the detection groove G2, and no cover is provided. In the case of the sensor disclosed in the above-mentioned Patent Document 2 (Japanese Patent No. 4987162), the detection groove G2 is not provided on the force receiving body 30 side. In the basic sensor used in the present invention, by providing the detection groove G2 also on the force receiving body 30 side, the force receiving body 30 itself has flexibility, and the detection sensitivity of the 6-axis force sensor shown in the present application is improved. I am trying.

  After all, this basic sensor includes a strain generating body 10 having a diaphragm portion 11, a force receiving body 30 having a diaphragm portion 31, a connecting member 20 for connecting both diaphragm portions 11 and 31, and an XYZ three-dimensional orthogonal coordinate system. A strain detection board 40 disposed at the position of the origin O and joined to the diaphragm unit 11; and a detection circuit (circuit mounted on the circuit board 50) that outputs a force to be detected as an electrical signal; It has a function of detecting a force component in a predetermined axis direction and a moment component around the predetermined axis in the XYZ three-dimensional orthogonal coordinate system.

  The screw holes 15 formed at four locations on the side wall portion 12 of the strain body 10 are through holes (screws are not cut) for fixing the strain body 10 to an external object. In the side sectional view of the lower part of FIG. 2, a state in which the screws N are inserted through the left and right screw holes 15 is depicted. These screws N are screwed into female screws in screw holes formed in an object (in the embodiment described in §3, the inner structure 200) disposed above the strain body 10. In this way, the strain body 10 is firmly fixed to the object by the four screws N.

  As shown in the side sectional view of the lower stage of FIG. 2, four openings 33 are provided on the outer peripheral portion of the side wall 32 of the force receiving body 30. Each opening 33 is formed at a position directly below each screw hole 15 and is used to insert a tool (driver) for rotating the screw N inserted through the screw hole 15.

  3 is a bottom view of the basic structure shown in FIG. 1, and FIG. 4 is a bottom view showing a state in which four screws N are inserted through the basic structure shown in FIG. As described above, in the outer peripheral portion of the force receiving body 30, an opening 33 (as shown in the drawing) for inserting a tool (driver) for rotating the screw N inserted through the screw hole 15 of the strain body 10. A U-shaped cutout portion formed from the outer periphery of the force receiving body 30 toward the central axis is formed.

  In order to attach the basic sensor to the counterpart object (in the case of the embodiment described in §3, the inner structure 200), four openings 33 are provided from the lower surface side of the force receiving body 30 using the openings 33 at four locations. The four screws N may be fixed by inserting the screws N through the screw holes 15 of the strain body 10 and rotating them with a tool (driver). FIG. 4 shows a state where the fixing with the four screws N is completed in this way.

  While the opening 33 is formed at a position along the X axis or the Y axis, respectively, the force receiving body 30 is positioned below the four positions at 45 ° on the outer periphery of the force receiving body 30. A screw hole 35 is formed for fixing to the arranged object (in the case of the embodiment described in §3, the outer structure 100).

  FIG. 5 is a top view (upper view (a)) and a side sectional view (lower view (b)) showing a state where the cover 18 of the basic structure shown in FIG. 1 is removed. Here, the top view in FIG. 5 corresponds to the top view in FIG. 2 rotated clockwise by 45 °, and the side cross-sectional view in FIG. 5 shows the structure shown in FIG. The cross section cut | disconnected in the position of WW is shown. Therefore, screw holes 35 appear on the left and right in this side sectional view. A female screw is formed inside the screw hole 35 formed in the force receiving body 30 and is led out from the side of the object (in the embodiment described in §3, the outer structure 100) disposed below. It is screwed with the tip of the four screws. Thereby, the force receiving body 30 can be firmly fixed to the object.

  Note that the contour shape of the detection groove G1 shown in the side sectional view of the lower stage of FIG. 5 is different from the contour shape of the detection groove G1 shown in the side sectional view of the lower stage of FIG. This is because the latter shows a cross section at the position of the cutting line WW, whereas the latter shows a cross section by the XZ plane. The lower side sectional view of FIG. 5 clearly shows that the cover bonding portion 19 is formed by the step structure generated by the difference between the contours f1 and f2. In addition, an insertion port that penetrates from the outside toward the detection groove G1 is provided in the side wall portion 12 of the strain generating body 10, and the circuit board 50 on which the detection circuit is mounted is inserted and fixed in the insertion port. Is also clearly shown. Between each piezoresistive element A (not shown in the lower side sectional view) provided on the upper surface of the strain detection board 40 and a detection circuit provided on the circuit board 50, wiring including bonding wires 47 is provided. Applied.

<<< §2. Specific basic sensor operation >>>
Subsequently, the operation of the basic sensor described in §1 will be described. Here, first, let us consider how the diaphragm portion 11 is deformed when an external force is applied to the basic sensor and what kind of stress is applied to the strain detection substrate 40. FIG. 6 is a sectional side view on the XZ plane showing a deformation state when the moment component + My around the Y-axis acts on the basic structure shown in FIG. In the figure, the Y axis is an axis that is oriented in the depth direction perpendicular to the paper surface at the origin O.

  In the present application, the sign of the moment component around the specific coordinate axis is positive in the rotation direction for advancing the right screw in the positive direction of the specific coordinate axis. Therefore, in the case of the illustrated example, the moment component + My is a force that rotates the force receiving body 30 clockwise around the Y axis as the center axis, and the moment component -My is a force receiving body around the Y axis as the center axis. This is the force to rotate 30 counterclockwise.

  The diaphragm portions 11 and 31 are film-like structural portions that are thinner than the other portions. Therefore, when an external force is applied, the diaphragm portions 11 and 31 are bent due to elastic deformation. Therefore, when the moment component + My acts on the force receiving member 30 in a state where the strain generating body 10 is fixed, the diaphragm portions 11 and 31 are deformed as illustrated, and the strain detecting substrate 40 is deformed as illustrated. Will occur. As a result, a stress as indicated by an arrow is applied to the upper surface of the strain detection substrate 40. That is, when attention is paid to the vicinity of the center of the upper surface of the strain detection substrate 40 (the immediate vicinity of the outside of the connection region of the connection member 20), a stress (tensile stress) is applied on the left side of the drawing and contracted on the right side of the drawing. Stress (compressive stress) is applied. As a result, a change occurs in the electric resistance of the piezoresistive element arranged at each position.

  For example, in the case of a P-type piezoresistive element formed on a silicon substrate, the resistance value increases when a stress in the extending direction acts, and the resistance value decreases when a stress in the contracting direction acts. In the case of an N-type piezoresistive element, the opposite result occurs. Therefore, if a detection circuit for detecting such a change in the resistance value of the piezoresistive element is provided on the circuit board 50, the external force component acting on the force receiving body 30 can be detected as an electric signal.

  The stress applied to each piezoresistive element varies depending on the type of external force component acting on the force receiving body 30. For example, when the negative moment component -My acts, a deformation mode that is reversed from the left and right of FIG. 6 is obtained. FIG. 7 is a cross-sectional side view on the XZ plane showing a deformation state when a force component + Fz in the Z-axis direction acts on the basic structure shown in FIG. When the central portion of the strain detection substrate 40 is pushed upward (Z-axis positive direction) and attention is paid to the vicinity of the center of the upper surface of the strain detection substrate 40, stress is applied in the extending direction at either the left or right position. When a negative force component -Fz (a force component directed downward in FIG. 7) is applied, conversely, stress is applied in a contracting direction at either the left or right position.

  FIG. 8 is a top view showing in detail the arrangement of the eight sets of piezoresistive elements A shown in FIG. For convenience of explanation, eight sets of piezoresistive elements are denoted by reference numerals A1 to A8. In addition, the hatching in FIG. 8 indicates a formation region of the piezoresistive elements A1 to A8, and does not indicate a cross section.

  Specifically, in the case of this example, the first piezoresistive element A1 and the second piezoresistive element A1 and the second piezoresistive element A2 that are arranged along the X-axis positive region so that the X-axis direction is the longitudinal direction on the upper surface of the strain detection substrate 40 The piezoresistive element A2, the third piezoresistive element A3 and the fourth piezoresistive element A4 arranged along the X-axis negative region so that the X-axis direction is the longitudinal direction, and the Y-axis direction being the longitudinal direction. The fifth piezoresistive element A5 and the sixth piezoresistive element A6 arranged along the Y-axis positive region so as to be in the direction, and along the Y-axis negative region so that the Y-axis direction is the longitudinal direction. A seventh piezoresistive element A7 and an eighth piezoresistive element A8 are provided.

  Here, the first to eighth piezoresistive elements A1 to A8 are composed of piezoresistive elements of the same material and the same size, and their electrical characteristics are the same. Therefore, if stress is applied to each element under the same condition, the same resistance value change occurs. Further, the arrangement pattern of the piezoresistive elements A1 to A8 is symmetric with respect to the XZ plane and the YZ plane, and the plane pattern shown in the top view of FIG. The Y-axis is also a line-symmetric figure.

  FIG. 9 is a table showing changes in resistance values of the eight sets of piezoresistive elements A1 to A8 shown in FIG. Each column in the row labeled “+ Mx” in the figure indicates a change in resistance value when a moment component + Mx around the positive X-axis acts on the force receiving member 30, and each column in the row labeled “+ My”. Indicates a change in resistance value when a moment component + My about the positive Y-axis acts on the force receiving member 30, and each column in the row labeled “+ Fz” indicates the force in the Z-axis positive direction on the force receiving member 30. The resistance value change when the component + Fz acts is shown. Here, “+” indicates that the resistance value increases, “−” indicates that the resistance value decreases, and “0” indicates that the resistance value does not change.

  In the table of FIG. 9, it can be easily understood that the result in the column of “+ My” becomes like this by looking at the modification of FIG. Since the eight sets of piezoresistive elements A1 to A8 are all P-type piezoresistive elements, considering the modification of FIG. 6, in the top view shown in FIG. It can be seen that the contraction stress acts to decrease the resistance value, and the elements A3 and A4 are subjected to the stress extending in the longitudinal direction to increase the resistance value. On the other hand, for the elements A5 to A8, since the stretching stress in the longitudinal direction is not generated, the resistance value does not change. The reason why the result in the column “+ Mx” is obtained is also the same.

  On the other hand, it can be easily understood that the result of the column of “+ Fz” becomes like this by looking at the modification of FIG. If the deformation | transformation aspect of FIG. 7 is considered, in the top view shown in FIG. 8, it turns out that the stress which extends to a longitudinal direction acts on all the piezoresistive elements A1-A8, and resistance value increases. In addition, when reverse-direction moment components “−Mx” and “−My” and a reverse direction force component “−Fz” are applied, the result obtained by reversing the signs shown in the table of FIG. 9 is obtained. Become.

  Based on the results shown in the table of FIG. 9, it can be seen that the detection circuit shown in FIGS. 10 and 11 can detect the moment component My around the Y axis and the moment component Mx around the X axis.

  In the detection circuit shown in FIG. 10, the first piezoresistive element A1 and the second piezoresistive element A2 are arranged on the first opposite side, and the third piezoresistive element A3 and the fourth piezoresistive element A4 are arranged. This is a circuit that detects a moment component My around the Y-axis using a Wheatstone bridge arranged on the second opposite side. When a predetermined power supply voltage is supplied from the DC power supply E, the terminals Ty1 and Ty2 maintain an equipotential while the bridge maintains the equilibrium condition. However, when the equilibrium state is lost, a potential difference Vy is generated between the two terminals. It will be. This potential difference Vy becomes an electric signal indicating the direction and magnitude of the moment component My around the Y axis.

  For example, when the moment component + My acts, as shown in the table of FIG. 9, the resistance values of the piezoresistive elements A1 and A2 decrease and the resistance values of the piezoresistive elements A3 and A4 increase, so that the terminal Ty1 side is positive, the terminal A voltage Vy that is negative on the Ty2 side is generated. When the counterclockwise moment component -My is applied, the sign of the voltage Vy is reversed. Further, if the applied moment component is large, the absolute value of the voltage Vy is also large.

  Similarly, the detection circuit shown in FIG. 11 has a fifth piezoresistive element A5 and a sixth piezoresistive element A6 arranged on the first opposite side, and a seventh piezoresistive element A7 and an eighth piezoresistive element. This is a circuit for detecting the moment component Mx around the X axis using a Wheatstone bridge in which A8 is arranged on the second opposite side. When a predetermined power supply voltage is supplied from the DC power supply E, the terminals Tx1 and Tx2 maintain an equipotential while the bridge maintains the equilibrium condition. However, when the equilibrium state is lost, a potential difference Vx occurs between the terminals. It will be. This potential difference Vx becomes an electric signal indicating the direction and magnitude of the moment component Mx around the X axis.

  Note that when the moment component Mx acts, the resistance values of the piezoresistive elements A1 to A4 do not change, so the detection circuit shown in FIG. 10 does not erroneously detect the moment component Mx. Further, when the force component Fz is applied, all the resistance values of the piezoresistive elements A1 to A8 are increased. Therefore, the detection circuit shown in FIG. 10 maintains the equilibrium condition of the bridge, and the force component Fz is There is no false detection. Similarly, the detection circuit shown in FIG. 11 does not erroneously detect the moment component My and the force component Fz. As described above, the detection circuit shown in FIGS. 10 and 11 can obtain an accurate detection value from which interference of other axis components is eliminated.

  The detection circuits shown in FIGS. 10 and 11 are both circuits that perform differential detection using a Wheatstone bridge, and are mounted on the circuit board 50. Since the difference detection is performed, even if a change occurs in the electrical characteristics of each piezoresistive element due to a change in the actual use environment (particularly the temperature environment), the influence is not output as a detection value. For example, even if the electrical resistance of the eight sets of piezoresistive elements increases or decreases due to temperature changes, these increases and decreases are phenomena that occur for all eight sets of piezoresistive elements. The balanced condition of the bridge circuit is maintained as it is, and no detection voltage is output. As described above, the detection circuits shown in FIGS. 10 and 11 can perform accurate detection without the influence of the actual use environment.

  Note that, based on the result in the column “+ Fz” in the table of FIG. 9, it can be seen that the force component in the Z-axis direction can be detected as the variation amount of the sum of the resistance values of the eight pairs of piezoresistive elements A1 to A8. That is, if the sum of the resistance values of the eight sets of piezoresistive elements A1 to A8 in a state where no external force is applied is measured as a reference value, if the sum of the resistance values increases from the reference value, the increase amount Indicates the magnitude of the force component + Fz in the Z-axis positive direction. If the sum of the resistance values decreases from the reference value, the decrease indicates the magnitude of the force component -Fz in the Z-axis negative direction. Become. However, since a difference cannot be detected for the force component in the Z-axis direction, a detection error due to a change in the actual usage environment is included.

  However, when used for the force sensor described in §3 and later, it is sufficient that the basic sensor has a function of detecting the moment component Mx around the X axis and the moment component My around the Y axis. The function of detecting the force component Fz is not necessary. Therefore, when the sensor described here is used as the basic sensor for the force sensor according to the present invention, no trouble is caused even if the force component Fz in the Z-axis direction cannot be accurately detected.

<<< §3. Structure of the first embodiment >>
Here, the structure of the first embodiment of the force sensor according to the present invention will be described. FIG. 12 is a cross-sectional view of the force sensor according to the first embodiment. This force sensor has a function of detecting a force component in a desired coordinate axis direction and a moment component around the desired coordinate axis in a three-dimensional orthogonal coordinate system. Therefore, here, an αβγ three-dimensional orthogonal coordinate system is defined with the α axis in the right direction of the drawing, the β axis in the upward direction, and the γ axis in the front direction perpendicular to the paper surface, and the following explanation will be given.

  In the description of the basic sensor described in §1 and §2, the XYZ three-dimensional orthogonal coordinate system is defined, and the function of detecting the moment component Mx around the X axis and the moment component My around the Y axis has been described. In this application, for the sake of convenience, the three-dimensional orthogonal coordinate system used for explaining the operation of the basic sensor is an XYZ three-dimensional orthogonal coordinate system, and the three-dimensional orthogonal coordinate system used for explaining the operation of the force sensor according to the present invention is an αβγ three-dimensional orthogonal coordinate system. I will make a distinction. The XYZ three-dimensional orthogonal coordinate system is a local coordinate system defined for each basic sensor, whereas the αβγ three-dimensional orthogonal coordinate system is a global coordinate system defined for the entire force sensor. .

  FIG. 12 is a cross-sectional view of the force sensor cut along the αβ plane. A point Q shown in the center of the figure indicates the origin of the αβγ three-dimensional orthogonal coordinate system (the γ-axis is the plane of the paper at the point Q). Becomes an axis orthogonal to the This force sensor includes a force component Fα acting in the α-axis direction, a force component Fβ acting in the β-axis direction, a force component Fγ acting in the γ-axis direction, a moment component Mα acting around the α-axis, and a β-axis around It functions as a 6-axis force sensor capable of detecting 6 components of the acting moment component Mβ and the acting moment component Mγ.

  As shown in the figure, the basic components of the force sensor are a cylindrical outer structure 100 having a housing space therein, an inner structure 200 housed in the housing space, and an outer side of the outer structure 100. 3 is an outer shell structure 300, three sets of basic sensors S1, S2, S3, and arithmetic means not shown. As will be described later, the calculation means has a function of performing calculations necessary for obtaining six components to be detected based on the outputs of the basic sensors S1 to S3.

  The basic sensors S <b> 1 to S <b> 3 are configured by a strain body 10, a connection member 20, and a force receiving body 30 as illustrated. Here, in order to distinguish these three sets of basic sensors from each other, different symbols “S1 to S3” are given, but all of these three sets of basic sensors have been described in §1 and §2. This is the basic sensor S. In other words, three sets of basic sensors S described in §1 and §2 are used in the force sensor according to the first embodiment. Since the structure of the basic sensor S has already been described in detail, the internal structure of each basic sensor is not shown in the following drawings. Therefore, FIG. 12 is basically a cross-sectional view, but a top view of the basic sensors S1 to S3 is shown.

  The inner structure 200 is a columnar structure whose cross section is a regular triangle, and is arranged so that the γ-axis becomes the central axis. On the other hand, the outer structure 100 and the outer shell structure 300 are constituted by concentric cylindrical structures having the γ-axis as a common central axis. Three sets of basic sensors S <b> 1 to S <b> 3 are arranged between the side surface of the inner structure 200 and the inner peripheral surface of the outer structure 100, and serve to connect the two. That is, in the first embodiment, the outer structure 100 is configured by a cylindrical structure that houses the inner structure 200 therein, and each of the basic sensors S1 to S3 is the cylindrical outer structure 100. The outer connection point on the inner peripheral surface of the inner structure 200 and the inner connection point on the outer peripheral surface of the inner structure 200 are connected to each other.

  Here, in order to describe a specific arrangement of each of the basic sensors S1 to S3, on the αβ plane, the α axis direction is set to 0 °, and azimuth angles up to 360 ° are defined counterclockwise. Further, as shown, in addition to the α axis and the β axis, a δ axis and an ε axis are defined. The α-axis, β-axis, δ-axis, and ε-axis are all axes on the αβ plane, and their azimuth angles are 0 °, 90 °, 210 °, and 330 ° (all are positive for each axis). Direction azimuth). Therefore, when attention is paid to the three axes of the β axis, the δ axis, and the ε axis, these three axes are axes that form 120 ° with respect to each other on the αβ plane. And 3 sets of basic sensors S1-S3 are arrange | positioned along these 3 axes | shafts.

  Specifically, the first basic sensor S1 is arranged such that the β axis is the central axis, and the outer connection point Jβ located at the intersection of the inner peripheral surface of the outer structure 100 and the β axis positive region. And the inner connection point Iβ located at the intersection of the outer peripheral surface of the inner structure 200 and the β-axis positive region is connected. Similarly, the second basic sensor S2 is arranged so that the δ axis becomes the central axis, and the outer connection point Jδ located at the intersection of the inner peripheral surface of the outer structure 100 and the δ axis positive region, The third basic sensor S3 is connected so as to connect the inner connection point Iδ located at the intersection of the outer peripheral surface of the inner structure 200 and the δ-axis positive region so that the ε-axis becomes the central axis. An outer connection point Jε located at the intersection of the inner peripheral surface of the outer structure 100 and the ε-axis positive region, and an inner connection located at the intersection of the outer peripheral surface of the inner structure 200 and the ε-axis positive region. The point Iε is connected so as to be connected.

  Note that, as described in §1, each of the strain generating body 10 and the force receiving body 30 constituting each basic sensor S is a plate-like member, so that the object surface of the counterpart to be attached is a plane. Is desirable. In the case of the first embodiment, the inner structure 200 has an equilateral triangle in cross section, and its outer peripheral surface is a flat surface. Therefore, there is no problem in attaching the strain body 10. On the other hand, if the outer structure 100 is made into a complete cylindrical shape, the inner peripheral surface becomes a curved surface, which is not preferable for attaching the plate-shaped force receiving body 30 as it is. Therefore, in the embodiment shown here, as shown in the drawing, a portion of the inner peripheral surface of the outer structure 100 to which the force receiving body 30 of the basic sensors S1 to S3 is attached is a flat shape. .

  For this reason, the outer structure 100 is slightly thicker in the vicinity of the portion that intersects the β-axis positive region, the δ-axis positive region, and the ε-axis positive region. Further, as shown in the figure, control grooves 111, 112, 113 are provided on the outer peripheral surface of this thick portion, and control protrusions 311, 312, 313 provided on the inner peripheral surface of the outer shell structure 300 are provided. It has a structure that can accommodate the tip. The functions of these control protrusions and control grooves will be described later.

  As described above, the strain body 10 of each of the basic sensors S1 to S3 is bonded and fixed to the inner connection points Iβ, Iδ, and Iε (indicated by black circles) provided at predetermined positions on the outer peripheral surface of the inner structure 200. The force receiving bodies 30 of the basic sensors S1 to S3 are joined and fixed to outer connection points Jβ, Jδ, Jε (shown by black circles in the figure) provided at predetermined positions on the inner peripheral surface of the outer structure 100. The As described in §1, the strain generating body 10 and the force receiving body 30 are actually fixed with screws, but the illustration of the screws is omitted in the drawings after FIG.

  As shown in FIG. 1B, a detection groove G <b> 1 is formed on the upper surface of the strain body 10, and a detection groove G <b> 2 is formed on the lower surface of the force receiving body 30. For this reason, in the structure shown in FIG. 12, the strain body 10 is not directly connected to the inner connection points Iβ, Iδ, Iε, and the force receiving body 30 is also directly connected to the outer connection points Jβ, Jδ, Jε. However, since these are directly fixed to the peripheral portion of each connection point, the basic sensors S1 to S3 are eventually connected to the outer connection points Jβ, Jδ, Jε provided at predetermined positions of the outer structure 100, respectively. The connecting function of indirectly connecting the inner connection points Iβ, Iδ, and Iε provided at predetermined positions of the inner structure 200 is achieved.

  Of course, a basic sensor having a structure in which one end is directly fixed to the outer connection point and the other end is directly fixed to the inner connection point may be used to directly connect the two connection points. Absent. Further, the inner structure 200 only needs to have a function of connecting the basic sensors S1 to S3 to the side surface thereof, and therefore may be configured by a cylindrical body having a hollow inside.

  The structure of the force sensor shown in FIG. 12 will be further clarified by referring to the longitudinal sectional view of FIG. The longitudinal sectional view shown in FIG. 13 corresponds to a longitudinal sectional view of the force sensor shown in FIG. 12 cut along the εγ plane. That is, the force sensor is a cross-sectional view cut along a cross section (position along the ε axis) corresponding to azimuth angles of 150 ° and −330 ° on the αβ plane. Also in FIG. 13, the basic sensor S3 is not a cross-sectional view but a side view.

  As described above, the outer structure body 100 and the outer shell structure body 300 are configured by concentric cylindrical structures having the γ-axis as a common central axis. A bottom plate member 150 is attached, and a disk-shaped connecting member 250 is attached above the outer shell structure 300. The upper part of the inner structure 200 is attached to the center of the lower surface of the connecting member 250, and the bottom plate member 150 is fixed to the upper surface of the pedestal 400.

  In FIG. 13, the right side wall (portion intersecting the ε-axis negative region) is thicker than the left side wall (portion intersecting the ε-axis negative region) of the outer structure 100 as described above. This is because a plane for connecting the force receiving body 30 of the third basic sensor S3 is provided on the inner surface of the right side wall as described above. A control groove 113 is provided on the outer peripheral surface of the thick portion, and the tip end portion of the control protrusion 313 provided on the inner peripheral surface of the outer shell structure 300 is accommodated.

  The force receiving body 30 of the third basic sensor S3 is fixed to the inner peripheral surface of the outer structure 100, and the strain body 10 is fixed to the outer peripheral surface of the inner structure 200. The third basic sensor S3 Thus, the outer connection point Jε and the inner connection point Iε are connected. Although not appearing in FIG. 13, the mounting conditions of the first basic sensor S1 and the second basic sensor S2 are exactly the same. In other words, the longitudinal sectional view taken along the β axis and the longitudinal sectional view taken along the δ axis of the force sensor shown in FIG. 12 are also similar to the longitudinal sectional view of FIG.

  In the embodiment shown here, the inner structure 200 is constituted by a triangular prism having a regular triangular cross section. In FIG. 13, the reason why the longitudinal section of the inner structure 200 is not symmetrical with respect to the γ-axis is that it shows a longitudinal section of a triangular prism. Inner connection points Iβ, Iδ, and Iε are provided at intersections with the β-axis, δ-axis, and ε-axis on each side surface of the inner structure 200 made of a triangular prism, and three sets of basic sensors S1 to S3 are respectively provided. The connecting function of connecting the inner connection points Iβ, Iδ, Iε and the outer connection points Jβ, Jδ, Jε provided at the opposing positions of the outer structure 100 is achieved.

  In the case of the embodiment shown here, as shown by hatching with dots in the figure, the outer structure 100 and the bottom plate member 150 are constituted by a cup-shaped structure that forms an integral structure made of the same material. The bottom surface is bonded to the top surface of the pedestal 400. Further, the circuit board 500 is fixed to the upper surface of the bottom plate member 150. The circuit board 500 is a semiconductor substrate on which an arithmetic circuit that constitutes arithmetic means to be described later is formed. Although illustration is omitted, between the basic sensors S1 to S3 and the circuit board 500, wiring for transmitting detection values detected by the basic sensors S1 to S3 is provided.

  On the other hand, in the case of this embodiment, as shown in the drawing by hatching with hatching, the inner structure 200, the connecting member 250, and the outer shell structure 300 are also constituted by a structure having an integral structure made of the same material. . The connecting member 250 has a function of connecting the inner structure 200 and the cylindrical outer shell structure 300 provided on the outer side thereof, and when an external force is applied, the inner structure 200, the connecting member 250, The outer shell structure 300 is displaced integrally.

  In the case of this example, the outer shell structure 300 is a cylindrical structure having the γ-axis as the central axis. As shown in FIG. 13, when the outer shell structure 300 is disposed so that the γ-axis is directed in the vertical direction, The connecting member 250 is configured by a circular plate-like member that covers the upper opening of the outer shell structure 300. The outer shell structure 300 is joined to the periphery of the lower surface of the plate-like member 250, and the upper surface of the inner structure 200 is connected to the center of the lower surface of the plate-like member 250.

  Of course, the connecting member 250 is not necessarily configured by a plate-like member, and may be configured by any structure as long as it is a structure that functions to connect the inner structure 200 and the outer shell structure 300. It doesn't matter. However, if the connecting member 250 is configured by a plate-like member that covers the upper opening of the cylindrical outer shell structure 300 as in the illustrated example, the advantage of serving as a cover that covers the inside of the apparatus can be obtained. .

  The outer structure 100, the inner structure 200, the connecting member 250, and the outer shell structure 300 are preferably composed of structures having rigidity as much as possible. If these are configured by a structure having sufficient rigidity, an external force to be detected can be efficiently transmitted to each of the basic sensors S1 to S3, and detection sensitivity can be improved. In the case of the embodiment shown here, the outer structure 100 and the bottom plate member 150 shown by hatching with dots in the figure are made of aluminum alloy, and the inner structure 200 shown by hatching with hatching in the figure, The member 250 and the outer shell structure 300 are also made of an aluminum alloy, and the pedestal 400 is also made of an aluminum alloy. Of course, the material of each part is not limited to an aluminum alloy, and for example, an iron-based alloy such as SUS (stainless steel) may be used.

  On the other hand, each basic sensor S1 to S3 has diaphragm portions 11 and 31, as shown in FIG. 1, and has the property of causing elastic deformation as shown in FIGS. 6 and 7, for example, when an external force is applied. Have. After all, the force sensor shown in FIG. 13 includes a first rigid body group including the outer structure 100, the bottom plate member 150, and the base 400, and a second rigid body group including the inner structure 200, the connecting member 250, and the outer shell structure 300. It has the structure which connected the rigid body group by basic sensors S1-S3 which can be elastically deformed.

  Therefore, for example, when the base 400 is fixed and some external force is applied to the connecting member 250 or the outer shell structure 300, the basic sensors S1 to S3 are elastically deformed by the external force. The second rigid body group is displaced with respect to one rigid body group. Conversely, when an external force is applied to the first rigid body group in a state where the second rigid body group is fixed, the first rigid body group is displaced relative to the second rigid body group. However, since these phenomena are fundamentally the same according to the law of action and reaction, in the present application, the following explanation will be given taking the former case as an example.

  When the base 400 is fixed, the outer structure 100 is fixed in the cross-sectional view of FIG. In this state, when an external force is applied to the outer shell structure 300 (or the disk-like connecting member 250 connected thereabove), the external force is transmitted to the inner structure 200. The inner structure 200 is supported from three sides by the basic sensors S1 to S3. As described above, the basic sensors S1 to S3 are elastically deformed by the action of an external force. The body 200 is displaced within the accommodation space inside the outer structure 100.

  Here, the basic sensors S1 to S3 have a function of detecting the moment components Mx and My of the applied external force, and the detected values are given as electric signals to the arithmetic circuit on the circuit board 500 described above. The arithmetic circuit performs a predetermined arithmetic process on the detection values given from the basic sensors S1 to S3, so that the outer shell structure 300 (or the disk-shaped connecting member 250 connected above the outer shell structure 300). With respect to the external force applied to, the force components Fα, Fβ, Fγ in the respective coordinate axes and the moment components Mα, Mβ, Mγ around the coordinate axes are detected. Specific calculation contents will be described in detail in §4.

  As described above, the basic sensors S1 to S3 have a property of being elastically deformed by the action of an external force. That is, when an external force is applied, it is deformed in a mode corresponding to the external force, but when the external force is no longer applied, it returns to its original state. However, normally, the property of such elastic deformation is maintained only when the magnitude of the applied external force is within a predetermined allowable range. When excessive external force is applied, the property of elastic deformation is It will be damaged. In this case, the basic sensor cannot perform a normal detection function. Thus, the force sensor according to the first embodiment incorporates two control structures for preventing excessive external force from being applied to the basic sensors S1 to S3.

  The first control structure is realized by configuring the outer structure body 100 and the outer shell structure body 300 with concentric cylindrical structures having a common γ-axis as a central axis. As shown in FIG. 12, a predetermined gap is formed between the outer peripheral surface of the outer structure 100 and the inner peripheral surface of the outer shell structure 300. Therefore, by appropriately setting the size of the gap, the displacement of the outer shell structure 300 with respect to the outer structure 100 is controlled within an appropriate range so that excessive external force is not applied to the basic sensors S1 to S3. Yes. If the displacement of the outer shell structure 300 relative to the outer structure 100 can be controlled within an appropriate range, the displacement of the inner structure 200 relative to the outer structure 100 can also be controlled within a predetermined allowable range. ~ S3 can perform a normal detection function.

  In short, when the displacement of the inner structure 200 with respect to the outer structure 100 reaches a predetermined allowable range (that is, the magnitude of the acting external force allows each of the basic sensors S1 to S3 to perform a normal detection function. The outer structure 100 so that the outer peripheral surface of the outer structure 100 and the inner peripheral surface of the outer shell structure 300 are in contact with each other and further displacement is limited. The design may be such that the distance between the outer shell structure 300 and the outer shell structure 300 is set to a predetermined value.

  In the case of a specific force sensor prototyped by the inventor of the present application, that is, a structure having a diameter of 10 mm and a height of 7 mm is used as each of the basic sensors S1 to S3, and the outer shell structure 300 is a size having a diameter of 25 mm. In the case of the embodiment using the cylindrical structure, if the distance between the outer structure 100 and the outer shell structure 300 is set to about 10 to 20 μm, practically sufficient detection sensitivity can be obtained, and the basic sensor S1. It was possible to limit the external force applied to -S3 within a range in which a normal detection function can be performed.

  The second control structure adopted by the force sensor shown in FIG. 12 is a combination of a control protrusion and a control groove. As shown in the figure, control protrusions 311, 312, and 313 facing inward are provided on the inner peripheral surface of the outer shell structure 300, and tip portions of these control protrusions are provided on the outer peripheral surface of the outer structure 100. Control grooves 111, 112, and 113 are provided. Moreover, when the displacement of the inner structure 200 with respect to the outer structure 100 reaches a predetermined allowable range (that is, when the displacement of the outer shell structure 300 with respect to the outer structure 100 reaches a predetermined allowable range), The tip of each control projection and each control groove so that the tip of each control projection 311, 312, 313 is in contact with the groove forming surface of each control groove 111, 112, 113 and further displacement is limited. Is set to an appropriate value (in this embodiment, about 10 to 20 μm).

  Each of the basic sensors S1 to S3 can perform a normal detection function as long as the displacement of the inner structure 200 with respect to the outer structure 100 is within the allowable range described above. The control structure makes it possible to limit the external force applied to the basic sensors S1 to S3 within a range in which a normal detection function can be achieved.

  As shown in the figure, in the example shown here, the combination of the control projection 311 and the control groove 111 is arranged on the β axis, and the combination of the control projection 312 and the control groove 112 is arranged on the δ axis. The combination of the control protrusion 313 and the control groove 113 is arranged on the ε axis. As described above, if a total of three combinations of the control projection and the control groove are arranged at positions shifted by 120 °, efficient displacement control can be performed for external force components acting in various directions. become.

  In particular, the combination of the control protrusion 311 and the control groove 111 arranged on the β-axis controls the force applied to the first basic sensor S1 in the height direction (Z-axis direction in FIG. 1) within an allowable range. The combination of the control projection 312 and the control groove 112 arranged on the δ axis controls the force applied in the height direction to the second basic sensor S2 within an allowable range. The combination of the control protrusion 313 and the control groove 113 arranged on the ε axis is effective in controlling the force applied to the third basic sensor S3 in the height direction within an allowable range. Is.

  Thus, in the case of the embodiment shown in FIG. 12, the outer structure 100 and the outer shell structure 300 are constituted by a concentric cylindrical structure having the γ-axis as a common central axis, and the gap dimension between the two structures. By adopting two types of control structures, a first control structure for setting the value to an appropriate value and a second control structure for arranging a combination of control protrusions and control grooves, each basic sensor S1 The external force applied to .about.S3 is maintained within a predetermined allowable range.

  In the example shown in FIG. 12, control protrusions directed inward are formed on the inner peripheral surface of the outer shell structure 300, and control grooves for accommodating the tip portions of these control protrusions are provided on the outer peripheral surface of the outer structure. Although the structure is adopted, the positional relationship between the control protrusion and the control groove may be reversed. That is, a control protrusion directed outward may be provided on the outer peripheral surface of the outer structure 100, and a control groove for accommodating the tip of the control protrusion may be provided on the inner peripheral surface of the outer shell structure 300. Also in this case, when the displacement of the inner structure 200 with respect to the outer structure 100 reaches a predetermined allowable range, the tip end portion of the control protrusion comes into contact with the groove forming surface of the control groove, and further displacement is limited. As described above, if the distance between the tip of the control protrusion and the groove forming surface of the control groove is set to an appropriate value, the external force applied to each of the basic sensors S1 to S3 can be maintained within a predetermined allowable range. The normal detection function can be maintained.

<<< §4. Detection Operation of First Embodiment >>>
Subsequently, the detection operation of the force sensor according to the first embodiment of the present invention described in §3 will be described. As described above, main components of the force sensor shown in FIG. 12 are the outer structure 100 having a housing space therein, the inner structure 200 housed in the housing space, and three sets of basic sensors. Calculation means (not shown in FIG. 12) that performs calculations based on S1 to S3 and the outputs of these basic sensors S1 to S3.

  The force sensor described in §3 is further provided with an outer shell structure 300 and a connecting member 250. These components are used for efficiently transmitting an external force to the inner structure 200. It is an auxiliary component and is not essential when configuring the force sensor according to the present invention.

  As shown in FIG. 13, this force sensor is provided with a bottom plate member 150 that covers the lower opening of the outer structure 100 when the outer structure 100 is arranged so that the central axis is directed in the vertical direction. The circuit board 500 is fixed to the upper surface of the bottom plate member 150. The arithmetic means described above is constituted by an arithmetic circuit formed on the circuit board 500, and a detection operation described later is executed by the arithmetic circuit formed on the circuit board 500. The bottom plate member 150 and the pedestal 400 are not essential components of the present invention, but are useful for supporting the circuit board 500.

  If a microprocessor is provided on the circuit board 500, a detection operation to be described later can be performed by digital calculation by the microprocessor. Furthermore, if necessary, this microprocessor can perform signal processing such as sensitivity correction, temperature correction, and other axis sensitivity correction.

  As shown in FIG. 13, the internal structure 200 is constituted by a columnar structure housed inside the outer structure 100 (in this example, a triangular prism whose section is an equilateral triangle), and three sets of basic sensors S1. ˜S3 are, as shown in FIG. 12, outer connection points Jβ, Jδ, Jε on the inner peripheral surface of the outer structure 100 and inner connection points Iβ, Iδ, Iε on the outer peripheral surface of the inner structure (triangular prism) 200. Will play a role in linking.

  Here, let us organize the basic functions of the basic sensors S1 to S3 used in the force sensor according to the present invention. The first basic function of each basic sensor is that outer connection points Jβ, Jδ, Jε provided at predetermined positions of the outer structure 100 and inner connection points Iβ, Iδ, Iε provided at predetermined positions of the inner structure 200. Is a connecting function for connecting The outer connection point and the inner connection point are not necessarily connected directly, and may be indirectly connected by fixing the end of the sensor around the periphery.

  In the case of the example shown in FIG. 12, detection grooves G1 and G2 are formed in the strain body 10 and the force receiving body 30 of the basic sensors S1 to S3, and the outer connection point and the inner connection point are the grooves G1, G2. Located in G2. For this reason, although both are not connected directly, it has become the state connected indirectly by joining the strain body 10 and the force receiving body 30 to the circumference | surroundings.

  The second basic function of each basic sensor is elastically deformed so that the relative positional relationship between the two points changes based on an external force acting on the other one of the outer connection point and the inner connection point in a fixed state. It is a transformation function. When an external force is applied to the force sensor shown in FIG. 12 (for example, when a force is applied to the inner structure 200 in a state where the outer structure 100 is fixed), the inner structure with respect to the outer structure 100 is used. The reason why 200 is displaced is that each of the basic sensors S1 to S3 has a deformation function of elastically deforming. In the case of the basic sensor S shown in FIG. 1, since at least the diaphragm parts 11 and 31 have a function of elastic deformation, elastic deformation as exemplified in FIGS. 6 and 7 occurs.

  And the 3rd basic function of each basic sensor is a detection function which detects the external force which acts on the other in the state where one of the outside connection point and the inside connection point is fixed. However, the moment component around the predetermined axis is sufficient for the external force to be detected. More specifically, the origin O located on the connecting line connecting the outer connecting point and the inner connecting point, the Z axis arranged on the connecting line, the X axis orthogonal to the Z axis, the Z axis, and the X axis When an XYZ three-dimensional orthogonal coordinate system having a Y-axis orthogonal to both axes is defined, it has a detection function for detecting the moment component Mx around the X-axis and the moment component My around the Y-axis of the applied external force. If you do.

  The specific basic sensors described in §1 and §2 can be said to be ideal sensors having the three basic functions described above. The calculation means performs a calculation using the detection values detected by each of the three sets of basic sensors S1 to S3, so that the force applied to the other of the outer structure 100 and the inner structure 200 in a state where one is fixed. And moments can be detected. Hereinafter, the detection principle will be described in detail.

  First, the relationship between each coordinate system is defined accurately. 1 and 2, the structure and operation of the basic sensor S have been described by defining the XYZ three-dimensional orthogonal coordinate system as shown. According to the description, the basic sensor S can detect the moment component Mx around the X axis and the moment component My around the Y axis in the XYZ coordinate system.

  The basic sensor S can detect the force component Fz in the Z-axis direction, but the force sensor of the present invention does not use the detected value of the force component Fz. When the inventor of the present application prototyped the basic sensor S and measured the sensitivity, the detection sensitivity of the moment components Mx and My was extremely high compared to the detection sensitivity of the force component Fz. For example, when the moment component Mx, My is measured by applying a moment having a magnitude of 10 N · cm and the force component Fz is measured by adding 10 N, the former sensitivity is 100, and the latter sensitivity is 1-10. It was about. Of course, since such a sensitivity difference is within a range that can be corrected by the amplifier circuit, there is no problem in using the basic sensor S as a three-axis sensor capable of detecting Mx, My, and Fz. Therefore, it is not necessary to detect the force component Fz in the Z-axis direction, and efficient detection using only Mx and My components with high sensitivity becomes possible.

  As described above, the XYZ three-dimensional orthogonal coordinate system is a local coordinate system defined for each basic sensor S, whereas the αβγ three-dimensional orthogonal coordinate system is a force or moment to be detected by the force sensor. This is a global coordinate system for indicating the direction of. In the case of the example shown in FIG. 12, the origin Q is defined inside the inner structure 200 (one point on the central axis of the triangular prism), and the αβγ cubic having the α, β, and γ axes orthogonal to each other at the origin Q. An original Cartesian coordinate system is defined. Therefore, the XYZ local coordinate system defined for each of the three basic sensors S1 to S3 is arranged in the αβγ global coordinate system.

  FIG. 14 is a cross-sectional view (cross-sectional view cut along the αβ plane) showing the directions of the coordinate axes (X-axis, Y-axis, Z-axis) of the basic sensors S1 to S3 that are components of the force sensor shown in FIG. is there. As shown in FIG. 1 (b), the origin O of the coordinate system of the basic sensor S is defined at the center position of the strain detection board 40, and the strain generating body 10 and the force receiving body 20 constituted by plate members are used. The XYZ coordinate system is defined so that the upper and lower surfaces are parallel to the XY plane. Therefore, also in FIG. 14, the XYZ coordinate system is defined by the same method for each of the basic sensors S1 to S3.

  That is, the origin O of the basic sensor S1 is located on the β axis, the origin O of the basic sensor S2 is located on the δ axis, and the origin O of the basic sensor S3 is located on the ε axis. The Z axis of the XYZ coordinate system defined for each of the basic sensors S1 to S3 is defined in a direction passing through the origin Q of the αβγ coordinate system (the direction toward the origin Q is the positive direction of the Z axis). In addition, each X axis and each Z axis defined for each of the basic sensors S1 to S3 are axes included in the αβ plane, and each Y axis defined for each of the basic sensors S1 to S3 is a γ axis. (The direction perpendicular to the paper surface of the drawing and toward the back side of the paper surface is the positive direction of the Y axis).

  As a result, the positive direction of each X axis defined for each of the basic sensors S1 to S3 is a counterclockwise tangential direction with respect to a circle centered on the origin Q in FIG. They are arranged so as to form 120 ° with respect to each other. That is, the Z-axis positive direction defined for the first basic sensor S1 matches the β-axis negative direction, the Z-axis positive direction defined for the second basic sensor S2 matches the δ-axis negative direction, The three basic sensors having the same detection sensitivity are arranged so that the positive Z-axis direction defined for the basic sensor S3 coincides with the negative ε-axis direction. When such a configuration is adopted, the calculation by the calculation means can be simplified.

  The calculating means includes a moment component Mx1 around the X axis detected by the first basic sensor S1, a moment component My1 around the Y axis detected by the first basic sensor S1, and a around X axis detected by the second basic sensor S2. Moment component Mx2, the moment component My2 around the Y axis detected by the second basic sensor S2, the moment component Mx3 around the X axis detected by the third basic sensor S3, and the Y axis detected by the third basic sensor S3 Based on the surrounding moment component My3, the force component Fα acting in the α-axis direction of the force acting on the force sensor, the force component Fβ acting in the β-axis direction, acting in the γ-axis direction on the basis of the following principle Force component Fγ, moment component Mα acting around the α axis, moment component Mβ acting around the β axis, and moment component Mγ acting around the γ axis It can be. Hereinafter, the detection principle of each component will be described.

  FIG. 15 is a cross-sectional view illustrating the detection operation of each of the basic sensors S1 to S3 when a positive force + Fα is applied to the inner structure 200 of the force sensor illustrated in FIG. For example, when a force + Fα that translates the outer shell structure 300 in the positive direction of the α-axis is applied in a state where the pedestal 400 is fixed, the inner structure 200 integrated with the outer shell structure 300 is also applied. , Force + Fα acts. In FIG. 15, the white arrow pointing in the positive direction of the α axis indicates the direction of action of the force + Fα.

  When such an external force + Fα acts on the inner structure 200, a moment in the rotational direction indicated by a white arrow in the figure acts on each of the basic sensors S1 to S3, and elastic deformation is performed in a predetermined manner. Will occur. The inner structure 200 is displaced in the positive direction of the α axis by such elastic deformation of the basic sensor. In other words, when the inner structure 200 is displaced in the positive direction of the α axis, a moment directed in the rotational direction indicated by the white arrow in the drawing acts on each of the basic sensors S1 to S3.

  Specifically, when a force + Fα in the α-axis positive direction acts on the inner structure 200, the lower surface of the figure (the surface in contact with the inner structure 200) is placed on the first basic sensor S1 in the α-axis positive direction. Therefore, as shown in the figure, a moment component -My1 (a force that rotates the vicinity of the origin O1 counterclockwise in the drawing) acts on the origin O1. In this case, since the force + Fα is a force that translates the inner structure 200 in the positive direction of the α axis, the moment component Mx1 around the X axis acting on the origin O1 is zero.

  On the other hand, the second basic sensor S2 is acted on by a force that moves the right upper surface in the drawing (the surface in contact with the inner structure 200) in the positive direction of the α axis. A positive moment component + My2 (in the drawing, a force that rotates the vicinity of the origin O2 in the clockwise direction) acts. Also in this case, the moment component Mx2 around the X axis acting on the origin O2 is zero.

  Similarly, the third basic sensor S3 is acted on by a force that moves the upper left surface of the drawing (the surface in contact with the inner structure 200) in the positive direction of the α axis. A moment component + My3 (a force that rotates the vicinity of the origin O3 in the clockwise direction in the drawing) acts on the positive axis. Also in this case, the moment component Mx3 around the X axis acting on the origin O3 is zero.

  As described above, when the force + Fα in the α-axis positive direction is applied, each of the basic sensors S1 to S3 obtains a detection value indicating the value of the moment component My around the Y-axis (moment component around the X-axis). The detection value indicating the value of Mx is zero). However, as can be seen from the arrangement of the basic sensors S1 to S3 shown in the figure, the detection sensitivity is slightly different for each basic sensor.

  That is, for each of the basic sensors S1 to S3, the force that contributes to the generation of the moment My around the Y axis is the side direction component of the inner structure 200 out of the external force + Fα applied to the inner structure 200. Thus, if the angle formed between each side surface and the α axis is φ, only the component “Fα × cosφ” is the force that contributes to the generation of the moment My. Here, in the case of the first basic sensor S1, φ = 0 °, so Fα × cosφ = Fα. However, in the case of the second and third basic sensors S2 and S3, φ = 60 °. Fα × cosφ = 1/2 · Fα.

  In other words, even if an external force + Fα having the same magnitude is applied to the inner structure 200, if the absolute value of the moment My around the Y axis output from the basic sensor S1 is 1, the basic sensor S2 , S3, the absolute value of the moment My around the Y axis is ½. Eventually, when an external force + Fα in the positive direction of the α-axis acts on the inner structure 200, moments Mx1 to Mx3 around the X axis and moments My1 to My3 around the Y axis output from the basic sensors S1 to S3. The detection values are summarized in the table shown in the lower part of FIG.

  For convenience of explanation, a white arrow in the cross-sectional view is attached with a sign + or − indicating the rotation direction, and is described as “−My1”, “+ My2”, “+ My3”. The detection values “Mx1”, “My1”,... In the lower table indicate variable values including signs (that is, positive or negative values). The same applies to FIGS. 16 to 20 described later.

  As shown in the table of FIG. 15, the detected values of the moments Mx1 to Mx3 around the X axis are all zero, and the detected values of the moments My1 to My3 around the Y axis are My1 = −1 and My2 = + 1 / 2, My3 = + 1/2. Here, the sign of each detection value indicates the rotation direction of the moment acting on each basic sensor (the rotation direction in which the right screw is advanced in the positive direction of each coordinate axis is positive), and the absolute value of each detection value is The ratio of the effective component which contributes to each basic sensor as a moment among the external forces which acted on the inner structure 200 is shown. Specifically, as described above, the angle formed between the maximum sensitivity direction of each basic sensor (the Y-axis direction when detecting Mx and the X-axis direction when detecting My) and the direction of the applied external force. If φ, the absolute value of each detected value is given by cosφ.

  If the basic sensors S1 to S3 are adjusted so that the values of the moments Mx and My can be output as linear detection values, the values in the table shown in the lower part of FIG. 15 are also obtained as linear output values. For example, when a unit external force + Fα is applied and detection values of My1 = −1, My2 = + 1/2, My3 = + 1/2 are obtained as shown in the figure, the double external force + 2Fα is When added, detection values of My1 = -2, My2 = + 1, My3 = + 1 are obtained. Further, when a unit external force -Fα directed in the reverse direction (α-axis negative direction) is applied, the sign of each detection value is reversed, and My1 = + 1, My2 = −1 / 2, My3 = −1 / 2. A detection value is obtained.

  FIG. 16 is a cross-sectional view showing the detection operation of each of the basic sensors S1 to S3 when a force + Fβ in the positive direction of the β axis is applied to the inner structure 200 of the force sensor shown in FIG. When such an external force + Fβ acts, a moment directed in the rotational direction indicated by the white arrow in the figure acts on each of the basic sensors S1 to S3.

  Specifically, although a force does not act on the first basic sensor S1 in the Z-axis direction with respect to the origin O1, the moment components are Mx1 = 0 and My1 = 0. On the other hand, the second basic sensor S2 is acted on by a force that moves the right upper surface (the surface that is in contact with the inner structure 200) in the positive direction of the β-axis, so that the origin O2 is Y-axis as illustrated. Although a negative moment component -My2 (a force that rotates the vicinity of the origin O2 counterclockwise in the figure) acts, the moment component Mx2 around the X axis is zero. Similarly, the third basic sensor S3 is acted on by a force that moves the upper left surface of the drawing (the surface in contact with the inner structure 200) in the positive direction of the β axis. A moment component around the positive axis + My3 (in the figure, a force that rotates the vicinity of the origin O3 clockwise) acts, but the moment component Mx3 around the X axis is zero.

  Again, if the angle between the maximum sensitivity direction of each basic sensor and the direction of the applied external force is φ, φ = 30 ° for the basic sensors S2 and S3, so the ratio of effective components contributing to moment generation Is cos 30 ° = √3 / 2. Therefore, when an external force + Fβ in the positive direction of the β axis acts on the inner structure 200, moments Mx1 to Mx3 around the X axis and moments My1 to My3 around the Y axis output from each of the basic sensors S1 to S3. The detected values are as shown in the table in the lower part of FIG.

  FIG. 17 shows the detection operation of each of the basic sensors S1 to S3 when a force in the positive direction of the γ axis + Fγ (force directed upward in the drawing) is applied to the inner structure 200 of the force sensor shown in FIG. It is a cross-sectional view shown. When such an external force + Fγ is applied, a moment directed in the rotational direction indicated by the white arrow in the figure is applied to each of the basic sensors S1 to S3.

  Specifically, since the force that moves the lower surface (the surface in contact with the inner structure 200) in the γ-axis positive direction acts on the first basic sensor S1, with respect to the origin O1, as illustrated, A moment component + Mx1 (a force that rotates the vicinity of the origin O1 in the clockwise direction in the direction of the arrow in the drawing) acts, but the moment component My1 around the Y axis is zero.

  Similarly, the second basic sensor S2 is acted on by a force that moves the upper right surface (the surface in contact with the inner structure 200) in the positive direction of the γ-axis, so that the origin O2 is X as shown in the figure. A moment component around the positive axis + Mx2 (in the drawing, a force that rotates the vicinity of the origin O2 in the clockwise direction in the direction of travel of the arrow) acts, but the moment component My2 around the Y axis is zero. Exactly in the same manner, the third basic sensor S3 is acted on by a force that moves the upper left surface (the surface in contact with the inner structure 200) in the positive direction of the γ-axis. A moment component + Mx3 (a force that rotates the vicinity of the origin O3 in the clockwise direction in the direction of the arrow in the drawing) acts, but the moment component My3 about the Y axis is zero.

  Again, if the angle between the maximum sensitivity direction of each basic sensor and the direction of the applied external force is φ, φ = 0 ° for any of the basic sensors S1 to S3, so that the active component contributing to moment generation The ratio of cos 0 ° = 1. Therefore, when an external force + Fγ in the positive direction of the γ-axis acts on the inner structure 200, the moments Mx1 to Mx3 around the X axis and the moments My1 to My3 around the Y axis output from the basic sensors S1 to S3. The detected values are as shown in the table in the lower part of FIG.

  18 is a cross-sectional view showing the detection operation of each of the basic sensors S1 to S3 when a moment + Mα about the positive α axis acts on the inner structure 200 of the force sensor shown in FIG. When such a moment + Mα acts, a moment in the rotational direction indicated by the white arrow in the figure acts on each of the basic sensors S1 to S3.

  Specifically, a force that moves the lower surface (the surface in contact with the inner structure 200) in the figure in the positive direction of the γ-axis (upwardly perpendicular to the paper surface) acts on the first basic sensor S1. As shown in the figure, the moment component + Mx1 (the force that rotates the vicinity of the origin O1 in the clockwise direction in the direction of the arrow in the drawing) acts, but the moment component My1 around the Y axis is zero. It is.

  On the other hand, the second basic sensor S2 is acted on by a force that moves the right upper surface (the surface in contact with the inner structure 200) in the negative γ-axis direction (vertically below the paper surface). As shown in the figure, the moment component -Mx2 (a force that rotates the vicinity of the origin O2 in the counterclockwise direction in the direction of the arrow in the drawing) acts, but the moment component My2 around the Y axis is zero. It is. Similarly, a force that moves the upper left surface (the surface in contact with the inner structure 200) in the γ-axis negative direction (downwardly perpendicular to the paper surface) acts on the third basic sensor S3. As shown in the figure, a moment component −Mx3 (a force that rotates the vicinity of the origin O3 in the counterclockwise direction in the direction of the arrow in the drawing) acts, but the moment component My3 around the Y axis is Zero.

  Again, if the angle between the maximum sensitivity direction of each basic sensor and the direction of the applied external force is φ, since φ = 0 ° for the basic sensor S1, the proportion of active components contributing to moment generation is Although cos 0 ° = 1, φ = 60 ° for the basic sensors S2 and S3, so the ratio of the active component contributing to the moment generation is cos 60 ° = 1/2. Accordingly, when a moment + Mα about the positive α axis acts on the inner structure 200, the moments Mx1 to Mx3 about the X axis and the moments My1 to My3 about the Y axis output from each of the basic sensors S1 to S3. The detected values are as shown in the table in the lower part of FIG.

  FIG. 19 is a cross-sectional view showing the detection operation of each of the basic sensors S1 to S3 when a moment + Mβ around the positive β axis acts on the inner structure 200 of the force sensor shown in FIG. When such a moment + Mβ acts, a moment directed in the rotational direction indicated by the white arrow in the figure acts on each of the basic sensors S1 to S3.

  Specifically, a moment that rotates the lower surface (the surface in contact with the inner structure 200) around the β axis, that is, a moment around the Z axis, acts on the first basic sensor S1. The moment component Mx1 around the X axis and the moment component My1 around the Y axis are zero.

  On the other hand, the second basic sensor S2 is acted on by a force that moves the upper right side of the drawing (the surface in contact with the inner structure 200) in the positive direction of the γ-axis (vertically upward on the paper surface). As shown, a moment component + Mx2 (in the figure, a force that rotates the vicinity of the origin O2 in the clockwise direction in the direction of travel of the arrow) acts, but the moment component My2 around the Y axis is zero. . Similarly, a force that moves the upper left surface (the surface in contact with the inner structure 200) in the γ-axis negative direction (downwardly perpendicular to the paper surface) acts on the third basic sensor S3. As shown in the figure, a moment component −Mx3 (a force that rotates the vicinity of the origin O3 in the counterclockwise direction in the direction of the arrow in the drawing) acts, but the moment component My3 around the Y axis is Zero.

  Again, if the angle between the maximum sensitivity direction of each basic sensor and the direction of the applied external force is φ, since φ = 0 ° for the basic sensor S1, the proportion of active components contributing to moment generation is Although cos 0 ° = 1, φ = 30 ° for the basic sensors S2 and S3, so the ratio of the active component contributing to the moment generation is cos 30 ° = √3 / 2. Accordingly, when the moment + Mβ around the β axis is applied to the inner structure 200, the moments Mx1 to Mx3 around the X axis and the moments My1 to My3 around the Y axis output from the basic sensors S1 to S3. The detected values are as shown in the table in the lower part of FIG.

  Note that the basic sensor S shown in FIG. 1 does not necessarily have sufficient flexibility to cause sufficient deformation when the moment component Mz around the Z-axis is applied. Therefore, in FIG. 19, when the moment + Mβ around the β-axis is applied to the inner structure 200 of the force sensor, the first basic sensor S1 is changed to the second and third basic sensors S2, S3. There is a possibility of causing an effect of suppressing the deformation that occurs. In §8.2 described later, a modification for improving this point is illustrated.

  FIG. 20 is a cross-sectional view showing the detection operation of each of the basic sensors S1 to S3 when a moment + Mγ about the positive γ-axis acts on the inner structure 200 of the force sensor shown in FIG. When such a moment + Mγ is applied, a force for rotating the inner structure 200 counterclockwise in the drawing is applied, and each of the basic sensors S1 to S3 faces the rotation direction indicated by the white arrow in the drawing. Moment acts.

  Specifically, since the force that moves the lower surface (the surface in contact with the inner structure 200) in the α-axis negative direction acts on the first basic sensor S <b> 1, the origin O <b> 1 is as shown in the figure. A moment component + My1 (in the drawing, a force that rotates the vicinity of the origin O1 in the clockwise direction) acts on the Y axis. At this time, the moment component Mx1 around the X axis is zero. Exactly in the same manner, for the second basic sensor S2, a force that rotates the vicinity of the origin O2 in the clockwise direction, that is, a moment component + My2 around the positive Y axis acts, but the moment component Mx2 around the X axis is zero. is there. For the third basic sensor S3, a force that rotates the vicinity of the origin O3 in the clockwise direction, that is, a moment component + My3 around the positive Y axis acts, but the moment component Mx3 around the X axis is zero.

  Here, considering the angle φ between the maximum sensitivity direction of each basic sensor and the direction of the applied external force, since φ = 0 ° for any basic sensor, the proportion of active components contributing to moment generation is , Cos 0 ° = 1. Therefore, when a moment + Mγ about the positive γ-axis acts on the inner structure 200, the moments Mx1 to Mx3 about the X-axis and the moments My1 to My3 about the Y-axis output from each of the basic sensors S1 to S3. The detected values are as shown in the table in the lower part of FIG.

  As described above, in the force sensor shown in FIGS. 12 and 13, the six-axis components Fα, Fβ, Fγ, Mα, Mβ, and Mγ of the external force are applied to the inner structure 200 with the base 400 fixed. In this case, what kind of output (detected values of moments Mx and My) is obtained from each of the basic sensors S1 to S3 has been described. FIG. 21 is a table summarizing these results.

  This table shows the results of applying positive force components + Fα, + Fβ, + Fγ and positive moment components + Mα, + Mβ, + Mγ as the six-axis components of the external force, respectively, but the negative component −Fα. , -F [beta], -F [gamma], -M [alpha], -M [beta], -M [gamma], the result obtained by reversing the sign of each detected value in the table is obtained. In addition, as described above, the absolute value of each detection value in this table is the reference value 1 when the maximum sensitivity direction of the basic sensor matches the direction of the applied external force (when φ = 0 °). And a relative value indicating the detection sensitivity of each of the basic sensors S1 to S3.

Considering the results shown in the table of FIG. 21, it can be seen that the six-axis components Fα, Fβ, Fγ, Mα, Mβ, and Mγ can be obtained based on the arithmetic expression as shown in FIG. See example of substituting numerical values). These arithmetic expressions are expressions in which the six detection values Mx1, My1, Mx2, My2, Mx3, My3 are multiplied by the respective detection values shown in the table of FIG. 21 as coefficients and added. For example, the arithmetic expression for calculating the force component Fα in the α-axis direction is Fα = K11 (−My1 + 1/2 · My2 + 1/2 · My3)
This is because the six detection values Mx1, My1, Mx2, My2, Mx3, My3 are detected values “0”, “−1” shown in the first row of the table of FIG. 21, respectively. ], “0”, “+1/2”, “0”, “+1/2” are multiplied as coefficients and added. The first coefficient K11 on the right side is a factor for scaling the final Fα value.

After all, in the case of this force sensor, based on the six sets of detected moments Mx1, My1, Mx2, My2, Mx3, My3 obtained from the three sets of basic sensors S1 to S3,
Fα = K11 (−My1 + ½ · My2 + ½ · My3)
Fβ = K12 (−√3 / 2 · My2 + √3 / 2 · My3)
Fγ = K13 (Mx1 + Mx2 + Mx3)
Mα = K14 (Mx1-1 / Mx2-1 / Mx3)
Mβ = K15 (√3 / 2 · Mx2−√3 / 2 · Mx3)
Mγ = K16 (My1 + My2 + My3)
By performing the following calculation, the force component Fα acting in the α-axis direction, the force component Fβ acting in the β-axis direction, the force component Fγ acting in the γ-axis direction, the moment component Mα acting around the α-axis, around the β-axis It is possible to detect the six-axis components of the moment component Mβ acting on the moment and the moment component Mγ acting around the γ-axis.

  An arithmetic circuit for performing such an operation may be incorporated on the circuit board 500. Note that K11, K12, K13, K14, K15, and K16 in the above equation are factors for performing appropriate scaling, respectively. In practice, in a calibration process using a prototype of a force sensor, a correct unit system is used. The value of each coefficient value may be determined so that the final output at is obtained.

  The important point here is that when the six-axis component is obtained by the above-described arithmetic expression, the detection value of each component can be obtained independently without receiving interference from other axis components. Hereinafter, this point will be shown by substituting specific detection values into the variables of the respective arithmetic expressions shown in FIG.

  First, let us consider the calculation formula for the force component Fα. Now, assuming that an external force + Fα is applied to the inner structure 200, detection values (Mx1 = 0, My1 = −1, Mx2 = 0, My2 = + 1/2, as shown in the first row of the table of FIG. 21). Mx3 = 0, My3 = + 1/2) is obtained. Therefore, by substituting these detection values into the expression in the first row of FIG. 22, Fα = K11 (− (− 1) + ½ (+ ½) + ½ (+ ½)) = K11 ( 3/2) is obtained. That is, a value of K11 (3/2) is output as the detected value of the force component Fα. If the coefficient K11 is set to an appropriate value, this detected value indicates a correct value for the force component Fα.

  At this time, even if the other five-axis components act simultaneously, the other-axis component is not erroneously detected as the detected value of the force component Fα if the calculation using the above-described arithmetic expression is performed. For example, if force component + Fβ is acting, My1 = 0, My2 = −√3 / 2, My3 = + √3 / 2 are obtained as detected values as shown in the second row of the table of FIG. However, if these detection values are substituted into the expression in the first row of FIG. 22, Fα = K11 (0 + 1/2 (−√3 / 2) +1/2 (+ √3 / 2)) = 0. Therefore, the detected value of the force component Fα is not output. If force component + Fγ is acting, as shown in the third row of the table of FIG. 21, My1 = 0, My2 = 0, and My3 = 0 are obtained as detection values, so the first of FIG. Substituting these detection values into the equation on the line results in Fα = K11 (0 + 0 + 0) = 0, which is not output as the detection value of the force component Fα.

  The same applies to the moment components Mα, Mβ, and Mγ. For example, assuming that moment components + Mα and + Mβ are acting, My1 = 0, My2 = 0, and My3 = 0 are obtained as detection values as shown in the fourth and fifth rows of the table of FIG. Therefore, if these detection values are substituted into the expression in the first row of FIG. 22, Fα = K11 (0 + 0 + 0) = 0, and no detection value of the force component Fα is output. If the moment component + Mγ is acting, My1 = + 1, My2 = + 1, and My3 = + 1 are obtained as detection values as shown in the sixth row of the table of FIG. If these detection values are substituted into the equation on the line, Fα = K11 (− (+ 1) +1/2 (+1) +1/2 (+1)) = 0, which is output as the detection value of the force component Fα. There is nothing. After all, the calculation result by the expression in the first row of FIG. 22 shows only the detected value of the force component Fα, and does not receive interference from other axis components.

  Next, consider an arithmetic expression for the force component Fβ. If an external force + Fβ is applied to the inner structure 200, detection values (Mx1 = 0, My1 = 0, Mx2 = 0, My2 = −√3 / 2, Mx3) as shown in the second row of the table of FIG. = 0, My3 = + √3 / 2). Therefore, by substituting these detection values into the expression in the second row of FIG. 22, Fβ = K12 (−√3 / 2 (−√3 / 2) + √3 / 2 (+ √3 / 2)). = K12 (3/2) is obtained. That is, the value K12 (3/2) is output as the detected value of the force component Fβ. If the coefficient K12 is set to an appropriate value, the detected value indicates a correct value for the force component Fβ.

  At this time, even if the other five-axis components act simultaneously, they are not erroneously detected. For example, if the force component + Fα is acting, My2 = + 1/2 and My3 = + 1/2 are obtained as detection values as shown in the first row of the table of FIG. 21, but the second value of FIG. Substituting these detection values into the equation on the line yields Fβ = K12 (−√3 / 2 (+1/2) + √3 / 2 (+1/2)) = 0, and the detection value of the force component Fβ Will not be output. If force component + Fγ is acting, My2 = 0 and My3 = 0 are obtained as detection values as shown in the third row of the table of FIG. 21, so the equation of the second row of FIG. If these detected values are substituted, Fβ = K12 (0 + 0) = 0 is obtained, and the detected value of the force component Fβ is not output.

  The same applies to the moment components Mα, Mβ, and Mγ. For example, assuming that moment components + Mα and + Mβ are acting, My2 = 0 and My3 = 0 are obtained as detection values as shown in the fourth and fifth rows of the table of FIG. Substituting these detection values into the expression in the second row of the equation, Fβ = K12 (0 + 0) = 0. Further, if the moment component + Mγ is acting, My2 = + 1 and My3 = + 1 are obtained as detection values as shown in the sixth row of the table of FIG. 21, so the equation of the second row of FIG. If these detected values are substituted into Fβ = K12 (−√3 / 2 (+1) + √3 / 2 (+1)) = 0, it is not output as the detected value of the force component Fβ. After all, the calculation result by the expression in the second row in FIG. 22 shows only the detected value of the force component Fβ, and does not receive interference from other axis components.

  Similarly, consider an arithmetic expression for the force component Fγ. If an external force + Fγ is applied to the inner structure 200, detection values (Mx1 = + 1, My1 = 0, Mx2 = + 1, My2 = 0, Mx3 = + 1, My3) as shown in the third row of the table of FIG. = 0). Therefore, by substituting these detection values into the expression on the third row in FIG. 22, a calculation result of Fγ = K13 ((+ 1) + (+ 1) + (+ 1)) = K13 × 3 is obtained. That is, a value of K13 × 3 is output as the detected value of the force component Fγ. If the coefficient K13 is set to an appropriate value, this detected value indicates a correct value for the force component Fγ.

  At this time, even if the other five-axis components act simultaneously, they are not erroneously detected. For example, if force components + Fα and + Fβ are acting, Mx1 = 0, Mx2 = 0, and Mx3 = 0 are obtained as detection values as shown in the first and second rows of the table of FIG. Therefore, if these detection values are substituted into the expression in the third row in FIG. 22, Fγ = K13 (0 + 0 + 0) = 0, and is not output as the detection value of the force component Fγ.

  The same applies to the moment components Mα, Mβ, and Mγ. For example, if the moment component + Mα is acting, Mx1 = + 1, Mx2 = −1 / 2, and Mx3 = −1 / 2 are obtained as detection values as shown in the fourth row of the table of FIG. When these detected values are substituted into the expression in the third row of FIG. 22, Fγ = K13 ((+ 1) + (− 1/2) + (− 1/2)) = 0, and the force component Fγ Are not output as detected values. Similarly, if the moment component + Mβ is acting, as shown in the fifth row of the table of FIG. 21, Mx1 = 0, Mx2 = + √3 / 2, and Mx3 = −√3 / 2 are detected values. Therefore, if these detection values are substituted into the expression in the third row of FIG. 22, Fγ = K13 ((0) + (+ √3 / 2) + (− √3 / 2)) = 0. Therefore, the detected value of the force component Fγ is not output.

  If the moment component + Mγ is acting, as shown in the sixth row of the table of FIG. 21, Mx1 = 0, Mx2 = 0, and Mx3 = 0 are obtained as detection values. Substituting these detection values into the equation on the line results in Fγ = K13 (0 + 0 + 0) = 0, and is not output as the detection value of the force component Fγ. After all, the calculation result by the expression in the third row in FIG. 22 shows only the detected value of the force component Fγ, and does not receive interference from other axis components.

  Next, consider an arithmetic expression for the moment component Mα. If the moment + Mα acts on the inner structure 200, the detection values (Mx1 = + 1, My1 = 0, Mx2 = −1 / 2, My2 = 0, Mx3 =) as shown in the fourth row of the table of FIG. -1/2, My3 = 0). Therefore, if these detection values are substituted into the expression in the fourth row of FIG. 22, Mα = K14 ((+ 1) −1/2 (−1/2) −1/2 (−1/2)) = An operation result of K14 (3/2) is obtained. That is, the value K14 (3/2) is output as the detected value of the moment component Mα. If the coefficient K14 is set to an appropriate value, the detected value indicates a correct value for the moment component Mα.

  At this time, even if the other five-axis components act simultaneously, they are not erroneously detected. For example, if force components + Fα and + Fβ are acting, Mx1 = 0, Mx2 = 0, and Mx3 = 0 are obtained as detection values as shown in the first and second rows of the table of FIG. Therefore, if these detection values are substituted into the expression in the fourth row of FIG. 22, Mα = K14 (0 + 0 + 0) = 0 is obtained and is not output as the detection value of the moment component Mα. If force component + Fγ is acting, Mx1 = + 1, Mx2 = + 1, and Mx3 = + 1 are obtained as detection values as shown in the third row of the table of FIG. Substituting these detection values into the equation on the line yields Mα = K14 ((+ 1) −1/2 (+1) −1/2 (+1)) = K14 (0) = 0, and the moment component Mα It is not output as a detection value.

  The same applies to the moment components Mβ and Mγ. For example, if the moment component + Mβ is acting, as shown in the fifth row of the table of FIG. 21, Mx1 = 0, Mx2 = + √3 / 2, and Mx3 = −√3 / 2 are obtained as detection values. Therefore, if these detected values are substituted into the expression on the fourth row in FIG. 22, Mα = K14 ((0) −1/2 (+ √3 / 2) −1/2 (−√3 / 2). )) = K14 (0) = 0, and is not output as a detected value of the moment component Mα.

  If the moment component + Mγ is acting, as shown in the sixth row of the table of FIG. 21, Mx1 = 0, Mx2 = 0, and Mx3 = 0 are obtained as detection values. If these detection values are substituted into the equation on the line, Mα == K14 ((0) −1/2 (0) −1/2 (0)) = 0, which is output as the detection value of the moment component Mα. It will never be done. As a result, the calculation result by the expression in the fourth row in FIG. 22 shows only the detected value of the moment component Mα, and does not receive interference from other axis components.

  Next, consider an arithmetic expression for the moment component Mβ. If the moment + Mβ acts on the inner structure 200, the detection values (Mx1 = 0, My1 = 0, Mx2 = + √3 / 2, My2 = 0, Mx3) as shown in the fifth row of the table of FIG. = -√3 / 2, My3 = 0). Therefore, when these detected values are substituted into the expression in the fifth row of FIG. 22, Mβ = K15 (√3 / 2 (+ √3 / 2) −√3 / 2 (−√3 / 2)) = An operation result of K15 (3/2) is obtained. That is, a value of K15 (3/2) is output as the detected value of the moment component Mβ. If the coefficient K15 is set to an appropriate value, the detected value indicates a correct value for the moment component Mβ.

  At this time, even if the other five-axis components act simultaneously, they are not erroneously detected. For example, if force components + Fα and + Fβ are acting, Mx2 = 0 and Mx3 = 0 are obtained as detection values as shown in the first and second rows of the table in FIG. If these detected values are substituted into the expression on the fifth line, Mβ = K15 (0 + 0) = 0, and the detected value of the moment component Mβ is not output. If force component + Fγ is acting, Mx2 = + 1 and Mx3 = + 1 are obtained as detection values as shown in the third row of the table of FIG. 21, so that the equation of the fifth row of FIG. When these detected values are substituted into Mβ = K15 (√3 / 2 (+1) −√3 / 2 (+1)) = K15 (0) = 0, it is output as a detected value of the moment component Mβ. There is nothing.

  The same applies to the moment components Mα and Mγ. For example, if the moment component + Mα is acting, Mx2 = −1 / 2 and Mx3 = −1 / 2 are obtained as detection values as shown in the fourth row of the table of FIG. Substituting these detection values into the expression in the fifth row, Mβ = K15 (√3 / 2 (−1/2) −√3 / 2 (−1/2)) = K15 (0) = 0 Therefore, it is not output as the detected value of the moment component Mβ.

  Further, if the moment component + Mγ is acting, Mx2 = 0 and Mx3 = 0 are obtained as detection values as shown in the sixth row of the table of FIG. 21, so the equation of the fourth row of FIG. If these detected values are substituted into Mβ = K15 (√3 / 2 (0) −√3 / 2 (0)) = K15 (0) = 0, the detected value of the moment component Mβ is output. There is nothing. As a result, the calculation result by the expression in the fifth row in FIG. 22 shows only the detected value of the moment component Mβ, and does not receive interference from other axis components.

  Finally, consider the equation for the moment component Mγ. If the moment + Mγ is applied to the inner structure 200, the detection values (Mx1 = 0, My1 = + 1, Mx2 = 0, My2 = + 1, Mx3 = 0, My3) as shown in the sixth row of the table of FIG. = + 1) is obtained. Therefore, by substituting these detection values into the expression in the sixth row in FIG. 22, a calculation result of Mγ = K16 ((+ 1) + (+ 1) + (+ 1)) = K16 × 3 is obtained. That is, a value of K16 × 3 is output as the detected value of the moment component Mγ. If the coefficient K16 is set to an appropriate value, this detected value shows a correct value for the moment component Mγ.

  At this time, even if the other five-axis components act simultaneously, they are not erroneously detected. For example, if force component + Fα is acting, My1 = -1, My2 = + 1/2, My3 = + 1/2 are obtained as detection values as shown in the first row of the table of FIG. When these detection values are substituted into the expression on the sixth line in FIG. 22, Mγ = K16 ((− 1) + (+ 1/2) + (+ 1/2)) = 0, and the moment component Mγ is detected. It is not output as a value.

  If force component + Fβ is acting, My1 = 0, My2 = −√3 / 2, My3 = + √3 / 2 are obtained as detected values as shown in the second row of the table of FIG. Therefore, if these detected values are substituted into the expression on the sixth line in FIG. 22, Mγ = K16 ((0) + (− √3 / 2) + (+ √3 / 2)) = 0. The detected value of the moment component Mγ is not output. On the other hand, if force component + Fγ is acting, My1 = 0, My2 = 0 and My3 = 0 are obtained as detection values as shown in the third row of the table of FIG. If these detected values are substituted into the equation on the line, Mγ = K16 ((0) + (0) + (0)) = 0 is obtained and is not output as a detected value of the moment component Mγ.

  The same applies to the moment components Mα and Mβ. If moment components + Mα and Mβ are acting, My1 = 0, My2 = 0, and My3 = 0 are obtained as detection values as shown in the fourth and fifth rows of the table of FIG. When these detection values are substituted into the expression on the sixth row in FIG. 22, Mγ = K16 ((0) + (0) + (0)) = 0 is output, and is output as the detection value of the moment component Mγ. There is nothing. As a result, the calculation result by the expression on the sixth line in FIG. 22 shows only the detected value of the moment component Mγ, and does not receive interference from other axis components.

  Thus, in the force sensor which concerns on the 1st Embodiment of this invention, the structure which accommodates the inner side structure 200 in the outer side structure 100 is taken, both are connected by 3 sets of basic sensors S1-S3, By calculating based on the moment components Mx and My detected by the basic sensors S1 to S3 by the calculation means, the six-axis components Fα, Fβ, Fγ, Mα, Mβ, Mγ of the external force acting on the αβγ coordinate system are obtained. It becomes possible to detect without receiving interference from other axes. As the basic sensors S1 to S3, it is only necessary to provide a function of detecting only the moment components Mx and My around the two axes. For example, a sensor having a relatively simple structure as illustrated in FIG. 1 is used. be able to.

<<< §5. Second Embodiment >>>
Subsequently, a force sensor according to a second embodiment of the present invention will be described. FIG. 23 is a longitudinal sectional view of the force sensor according to the second embodiment (a side view of the basic sensor S3). As can be seen by comparing the longitudinal sectional view of FIG. 23 and the longitudinal sectional view of FIG. 13, the structure of the second embodiment is almost the same as the structure of the first embodiment described above, but the outer shell structure 300. The connecting member 250 and the bottom plate member 150 are omitted, and a lid plate member 270 is provided instead.

  Also in the longitudinal sectional view of FIG. 23, the αβγ three-dimensional orthogonal coordinate system is defined similarly to the longitudinal sectional view shown in FIG. 13, and the illustrated sectional view shows the force sensor according to the second embodiment on the εγ plane. Corresponds to the cross section cut by. The cross-sectional view of the second embodiment cut along the αβ plane is obtained by omitting the outer shell structure 300 from the cross-sectional view shown in FIG. Thus, since the first embodiment and the second embodiment share the same constituent elements in many parts, the reference numerals of the respective constituent elements of the second embodiment have the same reference numerals as those of the first embodiment. The reference numerals of “A” are used for the corresponding constituent elements.

  For example, the outer structure 100A shown in FIG. 23 corresponds to the outer structure 100 shown in FIG. 13, and both have the same cylindrical structure except for the presence or absence of the control grooves 111 to 113. ing. However, although the bottom plate member 150 is connected to the lower surface of the outer structure 100 shown in FIG. 13 as an integral structure, components corresponding to the bottom plate member 150 are omitted in the force sensor shown in FIG.

  Further, the inner structure 200A shown in FIG. 23 corresponds to the inner structure 200 shown in FIG. 13, and both are columnar structures made of exactly the same triangular prism (transverse section is a regular triangle). However, on the upper surface of the inner structure 200 shown in FIG. 13, the connecting member 250 is connected as an integrated structure, and the outer shell structure 300 is connected as an integrated structure. However, in the force sensor shown in FIG. The components corresponding to the connecting member 250 and the outer shell structure 300 are omitted. Instead, the center portion of the lower surface of the disc-shaped cover plate member 270 having a step is joined to the upper surface of the inner structure 200A. In addition, a filling layer 280 made of silicon rubber is interposed between the peripheral edge of the lower surface of the cover plate member 270 and the upper surface of the outer structure 100A as shown in the figure. Since silicon rubber is a flexible material, the lid plate member 270 can be freely displaced with respect to the outer structure 100A.

  A pedestal 400A shown in FIG. 23 corresponds to the pedestal 400 shown in FIG. Each serves as a base for instructing the inner structure 100A or 100, but the bottom plate member 150 is joined to the upper surface of the pedestal 400 shown in FIG. 13, whereas the upper surface of the pedestal 400A shown in FIG. Is connected to the lower surface of the inner structure 100A. Further, the outer edge of the pedestal 400 shown in FIG. 13 extends to the position of the outer shell structure 300, but the outer edge of the pedestal 400A shown in FIG. 23 terminates at the position of the peripheral part of the inner structure 100A. Yes.

  A circuit board 500A shown in FIG. 23 corresponds to the circuit board 500 shown in FIG. However, the circuit board 500 is fixed to the upper surface of the bottom plate member 150. However, since the bottom plate member is omitted in the force sensor shown in FIG. 23, the circuit board 500A is fixed to the upper surface of the base 400A. In other words, in the case of the force sensor shown in FIG. 23, the pedestal 400A also functions as a bottom plate member.

  As described above, the cross-sectional view of the force sensor shown in FIG. 23 cut along the αβ plane is substantially the same as the cross-sectional view shown in FIG. 12 with the outer shell structure 300 omitted. Therefore, the detection principle of the force sensor according to the second embodiment is exactly the same as the detection principle of the force sensor according to the first embodiment described above, and the detection processing function of the circuit board 500A is §4. This is exactly the same as the detection processing function of the circuit board 500 described above.

  Comparing the first embodiment shown in FIG. 13 and the second embodiment shown in FIG. 23, it can be seen that the structure of the apparatus is simplified and the size of the latter is reduced compared to the former. The three basic sensors S1 to S3 used are common to both, and the sizes of the basic portions of the outer structure 100, 100A and the inner structure 200, 200A are also common to both. Both detection functions and sensitivities are the same.

  Further, in the former, a part of the upper part of the inner structure 200 has a structure that protrudes upward from the accommodation space provided inside the outer structure 100, whereas in the latter, the outer structure The entire inner structure 200A is housed in a housing space provided inside the body 100A. As long as at least a part of the inner structure is accommodated in the accommodating space provided inside the outer structure, the basic sensor S can be disposed between the two. You may make it the structure where a part protrudes from accommodation space. However, if the entire structure is accommodated in the accommodation space as in the latter case, the entire apparatus can be reduced in size.

  As described above, the second embodiment shown in FIG. 23 has an advantage in that the structure can be simplified and the size can be reduced as compared with the first embodiment shown in FIG. When the external force acting on the inner structure 200A is detected in a state where the base 400A is fixed, the external force to be detected may be transmitted to the cover plate member 270. However, as a disadvantage, since it is difficult to adopt a structure that controls displacement in all directions of the inner structure 200A, displacement control for preventing excessive external force from being applied to the basic sensors S1 to S3. Countermeasures are insufficient. The lid plate member 270 and the silicon rubber filling layer 280 serve as a cover for preventing dust and the like from entering the outer structure 100A, but are omitted when used in an environment where dust prevention measures are not required. It doesn't matter.

  In contrast to the second embodiment shown in FIG. 23, the first embodiment shown in FIG. 13 is provided with the outer shell structure 300 and the connecting member 250, so that the structure is slightly complicated and the size is slightly increased. However, since the inner space of the outer structure 100 is covered with the connecting member 250, the structure is such that dust and the like are difficult to enter. Further, the external force to be detected may be applied to the outer peripheral surface of the outer shell structure 300 or may be applied to the upper surface of the connecting member 250, so that it can be used in various real environments.

  Furthermore, an important merit of the first embodiment shown in FIG. 13 is that a control structure for preventing an excessive external force from being applied to each basic sensor S can be realized. That is, as described in §3, the outer structure body 100 and the outer shell structure body 300 are constituted by concentric cylindrical structures having the γ-axis as a common central axis, and the distance between the two is set to a predetermined value. The first control structure can be realized by setting, and the second control structure can be realized by a combination of the control protrusions 311, 312, 313 and the control grooves 111, 112, 113.

  Eventually, the first embodiment described in §3 and §4 is preferable for use in general applications, but the second embodiment is used for a specific application that requires a smaller sensor. Can be used.

<<< §6. Third embodiment >>>
Subsequently, a force sensor according to a third embodiment of the present invention will be described. FIG. 24 is a longitudinal sectional view of the force sensor according to the third embodiment (a side view of the basic sensor S3). As can be seen from a comparison between the longitudinal sectional view of FIG. 24 and the longitudinal sectional view of FIG. 13, the structure of the third embodiment is almost the same as the structure of the first embodiment. Are slightly different, and as a result, the directions of the three basic sensors S1 to S3 are different.

  Also in the longitudinal sectional view of FIG. 24, the αβγ three-dimensional orthogonal coordinate system is defined similarly to the longitudinal sectional view shown in FIG. 13. The illustrated sectional view shows the force sensor according to the third embodiment as εγ. Corresponds to a cross section cut along a plane. As the reference numerals of the constituent elements of the third embodiment, the reference numerals of the corresponding constituent elements of the first embodiment with “B” are used.

  First, the outer shell structure 300B and the connecting member 250B shown in FIG. 24 are the same as the outer shell structure 300 and the connecting member 250 shown in FIG. Also, the bottom plate member 150B, the pedestal 400B, and the circuit board 500B shown in FIG. 24 are the same as the bottom plate member 150, the pedestal 400, and the circuit board 500 shown in FIG. 13 (detection circuits formed on the circuit boards 500 and 500B). Is slightly different). However, the control projections 311 to 313 are not provided on the outer shell structure 300B, and the control grooves 111, 112, and 113 are not provided on the inner structure 100B side. Therefore, in this embodiment, the control structure is realized by setting the interval between the outer structure body 100B and the outer shell structure body 300B to a predetermined value.

  On the other hand, when the inner structure 200 shown in FIG. 13 and the inner structure 200B shown in FIG. 24 are compared, it will be understood that the shapes of the two are greatly different. As described above, the inner structure 200 shown in FIG. 13 is configured by a triangular prism having a regular triangular cross section, and three sets of basic sensors S1 to S3 are attached to each side surface of the triangular prism.

  On the other hand, the inner structure 200B shown in FIG. 24 is configured by a triangular pyramid having a regular triangular cross section. That is, when this inner structure 200B is cut along a plane parallel to the αβ plane, the obtained cut surface becomes an equilateral triangle (the three vertices are the β axis, δ axis, When the position of the cutting plane is moved upward along the γ-axis shown in FIG. 24, the equilateral triangle obtained in the cross section gradually becomes smaller.

  In the case of the third embodiment shown in FIG. 24, an inner connection point is provided on each side surface of the triangular pyramid constituting the inner structure 200B, and three sets of basic sensors S1 to S3 are respectively connected to the inner connection points. It has the connection function which connects the outer connection point provided in the opposing position of the outer side structure 100B. Therefore, the upper part of the inner peripheral surface of the outer structure 100B forms a facing surface that is parallel to each side surface of the triangular pyramid constituting the inner structure 200B. Each basic sensor S1 to S3 is connected between each side surface of the triangular pyramid constituting the inner structure 200B and each facing surface provided on the inner periphery of the outer structure 100B.

  FIG. 24 shows the connection state of the third basic sensor S3. The third basic sensor S3 includes an inner connection point Iθ (indicated by a black circle) provided on the side surface of the triangular pyramid constituting the inner structure 200B, and an opposing surface provided on the inner periphery of the outer structure 100B. The outer connection point Jθ (indicated by a white circle) is connected. Here, the straight line passing through the inner connection point Iθ and the outer connection point Jθ corresponds to the Z axis defined for the third basic sensor S3 and faces the direction that forms the inclination angle θ with respect to the αβ plane. Similarly, the first basic sensor S1 and the second basic sensor S2 are attached between the side surface of the triangular pyramid and its opposing surface.

  Eventually, in the case of the third embodiment, each Z-axis defined for each basic sensor S1 to S3 is directed in a direction that forms an inclination angle θ with respect to the αβ plane, and as a result, each basic sensor S1. Each of the Y axes defined for .about.S3 is oriented in a direction that forms an inclination angle .theta. With respect to the .gamma. Axis. In other words, in the third embodiment, the directions of the basic sensors S1 to S3 in the first embodiment shown in FIG. 13 are set in the positive direction of the γ axis by the elevation angle (inclination angle) θ with the origin Q as the center. It can be said that they are arranged at an angle.

  As described above, in the third embodiment, the orientation of the XYZ coordinate system defined for each basic sensor S1 to S3 is different from that in the first embodiment, and thus the moment component detected by each basic sensor S1 to S3. Based on Mx1, My1, Mx2, My2, Mx3, My3, in order to obtain the force components Fα, Fβ, Fγ in the direction of each coordinate axis and the moment components Mα, Mβ, Mγ around each coordinate axis in the αβγ coordinate system of the applied external force Necessary arithmetic processing is different from the arithmetic processing described in the detection operation of the first embodiment described in section 4 (the arithmetic processing based on the arithmetic expression shown in FIG. 22).

  That is, an arithmetic expression for calculating the six-axis components Fα, Fβ, Fγ, Mα, Mβ, and Mγ based on the moment components Mx1, My1, Mx2, My2, Mx3, My3 (an arithmetic expression that can eliminate other-axis interference) is The equation includes a trigonometric function related to the inclination angle θ. Since this arithmetic expression is a fairly complicated expression, it is not shown here, but can be obtained based on the geometrical arrangement of the basic sensors S1 to S3 based on the same principle as in the first embodiment. it can. Therefore, the circuit board 500B may be provided with an arithmetic circuit that performs necessary arithmetic processing based on the arithmetic expression.

  As described above, in the force sensor according to the third embodiment described here, each of the basic sensors S1 to S3 is attached in a direction inclined by the inclination angle θ with respect to the αβ plane. The arithmetic processing necessary for obtaining is slightly complicated. However, since the freedom degree of arrangement | positioning of each basic sensor S1-S3 increases, the design freedom degree of the whole apparatus can be improved. For example, various requests in design such as "I want to design a sensor that is as flat as possible while suppressing height" and "I want to design a sensor that can increase in height but have the smallest diameter" It becomes easy to meet.

<<< §7. Fourth Embodiment >>>
In the fourth embodiment described here, the basic principle of connecting three sets of basic sensors between the outer structure and the inner structure is the same as each of the embodiments described so far. The structure of each basic sensor and its connection method are greatly different.

  25 is a cross-sectional view of the force sensor according to the fourth embodiment cut along the αβ plane, and FIG. 26 is a vertical cross-sectional view cut along the εγ plane (all of the basic sensors S1 ′ to S3 ′). (A top view and a side view are shown for this part). The directions of the δ axis and the ε axis on the αβγ coordinate system are exactly the same as those of the embodiments described so far. As the reference numerals of the constituent elements of the fourth embodiment, the reference numerals of the corresponding constituent elements of the first embodiment with “C” added are used.

  As shown in FIG. 25, main components of the force sensor are an outer structure 100C, an inner structure 200C, and three sets of basic sensors S1 ′ to S3 ′. The outer structure body 100C and the inner structure body 200C are each constituted by a cylindrical structure body, and the inner structure body 200C is disposed inside the outer structure body 100C. In particular, in the case of the embodiment shown here, the outer structure 100C and the inner structure 200C are constituted by concentric cylindrical structures having the γ-axis as a common central axis.

  In the case of the first to third embodiments, the outer structures 100, 100A, 100B are cylindrical structures, but the inner structures 200, 200A, 200B arranged on the inner side thereof are columnar or conical structures. (Of course, a modified example in which the inside is hollow and cylindrical) is also possible. On the other hand, in 4th Embodiment shown here, the inner side structure 200C is also comprised by the cylindrical structure. This is because each of the basic sensors S1 ′ to S3 ′ has inner connection points Iβ, Iδ, Iε (shown by black circles in the figure) provided on the inner peripheral surface of the inner structure 200C and the inner peripheral surface of the outer structure 100C. This is because a structure for connecting the outer connection points Jβ, Jδ, and Jε (indicated by white circles in the figure) provided in FIG.

  As shown in FIG. 25, the first basic sensor S1 ′ is arranged in a direction extending along the β-axis, and the second basic sensor S2 ′ is arranged in a direction extending along the δ-axis. The sensor S3 ′ is arranged in a direction extending along the ε axis. Therefore, for convenience of explanation, the β axis is defined as a reference line corresponding to the first basic sensor S1 ′, the δ axis is defined as a reference line corresponding to the second basic sensor S2 ′, and the ε axis is defined as the first. 3 is defined as a reference line corresponding to the basic sensor S3 ′.

  Then, each reference line is a straight line that passes through the first sidewall of the outer structure 100C, the first sidewall of the inner structure 200C, the second sidewall of the inner structure 200C, and the second sidewall of the outer structure 100C. Thus, through holes are formed in the first side walls of the inner structure 200C through which the respective reference lines penetrate.

  For example, when the β axis that is the reference line corresponding to the first basic sensor S1 ′ is sequentially traced from the lower side of the figure (the negative direction of the coordinate axis β) to the upper side of the figure (the positive direction of the coordinate axis β), the reference is made. The lines indicate the first side wall (the lower wall in the figure) of the outer structure 100C, the first side wall (the lower wall in the figure) of the inner structure 200C, and the second side wall (the upper side in the figure) of the inner structure 200C. And a straight line that penetrates through the second side wall (the upper wall in the figure) of the outer structure 100C. An insertion hole 211 is formed in the first side wall (the lower wall in the figure) of the inner structure 200C.

  Similarly, when the δ axis that is the reference line corresponding to the second basic sensor S2 ′ is sequentially traced from the upper right (negative direction of the coordinate axis δ) to the lower left (positive direction of the coordinate axis δ) of the figure, The reference lines are the first side wall (upper right wall in the figure) of the outer structure 100C, the first side wall (upper right wall in the figure) of the inner structure 200C, and the second side wall (in the figure) of the inner structure 200C. (Lower left wall), a straight line passing through the second side wall (lower left wall in the figure) of the outer structure 100C. An insertion hole 212 is formed in the first side wall (the upper right wall in the figure) of the inner structure 200C.

  Further, when the ε axis that is a reference line corresponding to the third basic sensor S3 ′ is sequentially traced from the upper left (negative direction of the coordinate axis ε) to the lower right (positive direction of the coordinate axis ε) of the figure, The reference lines are the first side wall (upper left wall in the figure) of the outer structure 100C, the first side wall (upper left wall in the figure) of the inner structure 200C, and the second side wall (upper side of the figure) of the inner structure 200C. (Lower right wall), a straight line passing through the second side wall (lower right wall in the figure) of the outer structure 100C. An insertion hole 213 is formed in the first side wall (upper left wall in the figure) of the inner structure 200C.

  Three sets of basic sensors S1 ′ to S3 ′ used in the fourth embodiment described here are the basic sensors S1 to S3 (§) used in the first to third embodiments described so far. Although the structure is slightly different from the sensor described in 1 and §2, the basic function is the same. That is, the basic sensors S 1 ′ to S 3 ′ shown in FIG. 25 have a structure in which the hooks 21 to 23 are attached to the strain body 10. Here, for convenience of explanation, the hooks 21, 22, and 23 are denoted by different reference numerals, but the hooks are substantially the same structure. The strain body 10 is the same as the strain body 10 of the basic sensor S shown in FIG. 1, and the hook-shaped portions 21, 22, and 23 are elongate members for performing a connecting function.

  On the other hand, in the vicinity of the intersection with the reference line of the first side wall of the outer structure 100C, a diaphragm portion that is thinner than the other portions is formed, and one end of each of the basic sensors S1 ′ to S3 ′. Are joined to the diaphragm. Specifically, a mounting groove 121 is formed in the lower inner peripheral surface of the outer structure 100C shown in FIG. 25 to form a thin diaphragm portion 131, and the first basic sensor S1 ′. The end portion of the bowl-shaped portion 21 is joined to the inner surface of the diaphragm portion 131. Similarly, a mounting groove 122 is dug in the upper right inner peripheral surface of the outer structure 100C, a thin diaphragm portion 132 is formed, and the flange portion 22 of the second basic sensor S2 ′ is formed. The end portion is joined to the inner surface of the diaphragm portion 132, and a mounting groove 123 is dug in the upper left inner peripheral surface of the outer structure 100C, so that a thin diaphragm portion 133 is formed. The end portion of the bowl-shaped portion 23 of the third basic sensor S3 ′ is joined to the inner side surface of the diaphragm portion 133.

  After all, in the case of the fourth embodiment, each of the basic sensors S1 ′ to S3 ′ has an inner periphery of the first side wall of the outer structure 100C through which the corresponding reference line (β axis, δ axis, ε axis) passes. Outer connection points Jβ, Jδ, Jε provided on the surface and inner connection points Iβ, Iδ, Iε provided on the inner peripheral surface of the second side wall of the inner structure 200C through which the corresponding reference line passes, It has the connection function to connect through the insertion holes 211, 212, and 213 formed in the first side wall of the inner structure 200C through which the corresponding reference line passes.

  Further, as shown in FIG. 1 (b), a diaphragm portion 11 is provided in the strain generating body 10 of each basic sensor S1 ', S2', S3 ', so that each basic sensor S1', S2 ', S3 ′ has a deformation function that elastically deforms so that the relative positional relationship between the two connection points changes in addition to the connection function that links the outer connection points Jβ, Jδ, and Jε and the inner connection points Iβ, Iδ, and Iε. Will be.

  Further, in the case of the illustrated embodiment, the end portions of the flange portions 21, 22, and 23 are connected to diaphragm portions 131, 132, and 133 provided in the outer structure 100C. Therefore, the elastic deformation function of each basic sensor S1 ′, S2 ′, S3 ′ and the elastic deformation function of the diaphragm portions 131, 132, 133 can be operated in cooperation, and the inner structure 200C is fixed. When an external force is applied to the outer structure 100C in the state, the force sensor can be smoothly deformed.

  Of course, each of the basic sensors S1 ′ to S3 ′ has a detection function similar to that of the basic sensors S1 to S3 used in the first to third embodiments. That is, the origin O is defined on a connecting line connecting the outer connecting point and the inner connecting point, and the Z axis arranged on the connecting line, the X axis orthogonal to the Z axis, and both the Z axis and the X axis are defined. When an XYZ three-dimensional orthogonal coordinate system having an orthogonal Y axis is defined, each of the basic sensors S1 'to S3' has an external force acting on the outer structure 100C around the X axis in a state where the inner structure 200C is fixed. Moment component Mx and the moment component My around the Y-axis can be detected.

  Accordingly, as in the example shown in FIG. 14, for each of the basic sensors S1 ′ to S3 ′, the origin O is set at the center position of the strain detection substrate 40, and the Z-axis is defined in the directions of the coordinate axes β, δ, and ε. If the Y-axis is defined in the direction perpendicular to the page, the X-axis is defined in the direction perpendicular to both the Z-axis and the Y-axis, and the XYZ coordinate system is defined for each of the basic sensors S1 'to S3' The means performs an operation using the moment components Mx1, Mx2, Mx3 around the X axis and the moment components My1, My2, My3 around the Y axis detected by each of the basic sensors S1 'to S3', thereby obtaining the outer structure. For the body 100C and the inner structure 200C, the force components Fα, Fβ, Fγ of the external force acting on the other in the state where one of them is fixed and the moment component Mα, Mβ, Mγ can be obtained. A specific calculation method is the same as the calculation method described in §4, and a detection value that eliminates interference from other axes can be obtained by performing a calculation using the calculation formula shown in FIG.

  The internal structure of the force sensor according to the fourth embodiment is shown in detail in the longitudinal sectional view of FIG. As described above, the outer structure 100C and the inner structure 200C are configured by concentric cylindrical structures having the γ-axis as a common central axis. As shown in the figure, the outer structure 100C is provided with a disk-shaped top plate member 150C that covers the upper opening when the central axis γ is arranged in the vertical direction. A disc-shaped bottom plate member 250C that covers the lower opening is attached to the lower side of the inner structure 200C, and the bottom plate member 250C is fixed to the upper surface of the base 400C.

  FIG. 26 is a longitudinal sectional view of the force sensor shown in FIG. 25 cut along the εγ plane (the basic sensor S3 ′ is a side view), and the horizontal direction in the figure is the direction of the ε axis. A third basic sensor S3 ′ is arranged along the ε axis (reference axis). Specifically, the attachment groove 123 is dug in the inner peripheral surface of the left side wall (first side wall) of the outer structure 100C, and a thin diaphragm portion 133 is formed. The flange-like portion 23 constituting the third basic sensor S3 ′ has a left end joined to the inner side surface of the diaphragm portion 133, and is formed on the left side wall (first side wall) of the inner structure 200C. It extends rightward along the ε-axis (reference axis) through the insertion hole 213 formed. A diaphragm portion of the strain body 10 is connected to the right end portion of the bowl-shaped portion 23, and the strain body 10 is fixed to the inner peripheral surface of the right side wall (second side wall) of the inner structure 200C. Has been.

  Thus, the third basic sensor S3 ′ has an outer connection point Jε (intersection of the ε axis and the inner surface of the diaphragm 133) shown on the left side of the drawing and an inner connection point Iε (ε axis and the inner side shown on the right side of the drawing). And a connecting function of connecting through the insertion hole 213 with the inner peripheral surface of the structure 200C. In FIG. 26, only the cross-sectional portion obtained by cutting the bowl-shaped portions 21 and 22 along the εγ plane is shown for the first basic sensor S1 ′ and the second basic sensor S2 ′ in order to prevent the drawing from becoming complicated. However, the connection form of these basic sensors S1 'and S2' is exactly the same.

  Note that the β-axis, δ-axis, and ε-axis serving as reference lines for arranging the three basic sensors S1 ′, S2 ′, and S3 ′ intersect at the origin Q of the αβγ coordinate system. If 23 is comprised by a linear member, it will mutually contact in the origin Q vicinity. In order to avoid such mutual interference, at least some hooks of the basic sensors may be curved so as to avoid contact with hooks of other basic sensors.

  In the case of the illustrated example, the bowl-shaped portion 21 of the first basic sensor S1 ′ is constituted by a linear elongated cylindrical member (in the drawing, an elliptical cut surface is shown at the position of the origin Q). As shown in the figure, the bowl-shaped portion 23 of the third basic sensor S3 ′ is basically composed of a straight and elongated cylindrical member, but in the vicinity of the origin Q, above the bowl-shaped portion 21. It is curved upward so that it can pass through. On the other hand, the bowl-shaped part 22 of the second basic sensor S2 ′ is basically also constituted by a straight and elongated cylindrical member, but can pass under the bowl-shaped part 21 in the vicinity of the origin Q. It is curved downward (in the figure, an elliptical cut surface is shown below the origin Q).

  In the force sensor shown in FIG. 26, as shown by hatching in the drawing, the inner structure 200C and the bottom plate member 250C are configured by a cup-shaped structure that forms an integral structure made of the same material. The bottom surface is bonded to the top surface of the base 400C. On the other hand, as shown by hatching with dots in the figure, the outer structure 100C and the top plate member 150C are configured by a cup-shaped structure that is also formed of the same material and forms an integral structure.

  After all, this force sensor has a basic structure in which two sets of cup-shaped structures are connected by three sets of basic sensors S1 'to S3' having an elastic deformation function. When an external force is applied to the outer structure 100C or the top plate member 150C in the fixed state, as described above, it is possible to detect the six-axis components Fα, Fβ, Fγ, Mα, Mβ, and Mγ for the external force. become.

  In the fourth embodiment, a part of the basic sensors S1 ′ to S3 ′ (parts of the bowl-shaped portions 22 and 23) has a curved structure, and processing such as providing the insertion holes 211 to 213 in the inner structure 200C is necessary. However, as compared with the first embodiment, there is an advantage that the outer diameter can be designed to be small.

  As shown in FIG. 26, the circuit board 500C is fixed to the upper surface of the bottom plate member 250C. Although not shown, detection values Mx1, Mx2, Mx3, My1, My2, My3 detected by the basic sensors S1 'to S3' are provided between the basic sensors S1 'to S3' and the circuit board 500C. Wiring for transmission is provided, and an arithmetic circuit for performing calculation for obtaining the six-axis component based on these detection values is formed on the circuit board 500C.

  Similarly to the force sensor according to the first embodiment described above, the force sensor according to the fourth embodiment is also adapted to prevent an excessive external force from being applied to the basic sensors S1 ′ to S3 ′. These two control structures are incorporated.

  The first control structure is realized by configuring the outer structure body 100C and the inner structure body 200C with a concentric cylindrical structure body having the γ-axis as a common central axis. As shown in FIG. 26, a predetermined gap is formed between the inner peripheral surface of the outer structure 100C and the outer peripheral surface of the inner structure 200C. Therefore, by appropriately setting the size of the gap, the displacement of the outer structure 100C with respect to the inner structure 200C is controlled within an appropriate range so that excessive external force is not applied to the basic sensors S1 ′ to S3 ′. ing.

  In short, when the displacement of the outer structure 100C with respect to the inner structure 200C reaches a predetermined allowable range, the outer peripheral surface of the inner structure 200C and the inner peripheral surface of the outer structure 100C come into contact with each other, and further displacement occurs. The distance between the inner structure 200C and the outer structure 100C is set to a predetermined value so that the basic sensors S1 ′ to S3 ′ have the displacement of the outer structure 100C relative to the inner structure 200C as described above. What is necessary is just to design so that a normal detection function may be fulfill | permitted as long as it is in an allowable range.

  The second control structure adopted by the force sensor according to the fourth embodiment is a combination of the hook-shaped portions 21 to 23 and the insertion holes 211 to 213. For example, the bowl-shaped portion 23 shown in FIG. 26 is disposed so as to pass through the insertion hole 213 provided in the side wall of the inner structure 200C. Therefore, when the displacement of the outer structure 100C relative to the inner structure 200C reaches a predetermined allowable range, the insertion hole 213 formed in the inner structure 200C and the hook-like portion 23 (that is, the insertion hole 213 passing through the insertion hole 213) The gap with the insertion hole 213 is set to a predetermined value so that the further displacement is limited, and the basic sensor S3 ′ is outside the inner structure 200C. As long as the displacement of the structure 100C is within the allowable range, it may be designed to perform a normal detection function. The same applies to the basic sensors S1 'and S2'.

  In the embodiment shown in FIGS. 25 and 26, diaphragm portions 131, 132, and 133 are exposed on the outer peripheral surface of the outer structure 100C. For this reason, when an external force applied from the side acts directly on the diaphragm portions 131, 132, and 133, this portion may be directly deformed, and an accurate detection value may not be obtained.

  In order to avoid such an adverse effect, an outer shell structure 300C made of a cylindrical structure is provided on the outer side of the outer structure 100C as in the modification shown in FIG. The connecting member 350C may be provided, and the connecting member 350C may be bonded to the upper surface of the top plate member 150C to connect the outer shell structure 300C and the outer structure 100C. In this modification, when an external force is applied to the outer shell structure 300C or the connecting member 350C in a state where the pedestal 400C is fixed, the external force is transmitted to the outer structure 100C via the top plate member 150C. When the sensors S1 'to S3' are elastically deformed, the components hatched with dots in the figure are integrated and displaced. In addition, since the diaphragm portions 131, 132, and 133 are protected by the outer shell structure 300C, they are not directly subjected to the action of external force. In addition, since a predetermined gap is secured between the outer peripheral surface of the outer structure 100C and the inner peripheral surface of the outer shell structure 300C, free deformation of the diaphragm portions 131, 132, and 133 is hindered. There is nothing.

<<< §8. Various modifications >>
So far, the force sensor according to the present invention has been described based on the first to fourth embodiments. Here, some modifications to these embodiments will be described.

<8.1 Modification regarding the number of basic sensors>
In the embodiments described so far, three sets of basic sensors have been used. However, in implementing the present invention, the number of basic sensors is not limited to three sets. The force sensor according to the present invention can be configured using any number of basic sensors as long as there are three or more pairs. In short, the force sensor according to the present invention includes a plurality of n sets (provided that n ≧≧) between an outer structure having an accommodation space inside and an inner structure at least a part of which is accommodated in the accommodation space. The applied external force may be detected by connecting with the basic sensor of 3) and performing calculation using the detection values of these n sets of basic sensors by the calculation means.

  FIG. 28 is a cross-sectional view (a top view of the basic sensors S1 to S4) in which a force sensor according to a modification using four sets of basic sensors is cut along an αβ plane. Here, the basic sensor arranged in the upper part of the drawing is referred to as a first basic sensor S1, and hereinafter, the second basic sensor S2, the third basic sensor S3, and the fourth basic sensor S4 in the counterclockwise order. I will call it. The first basic sensor S1 is arranged so that the β-axis positive region is the central axis, and the second basic sensor S2 is arranged so that the α-axis negative region is the central axis, and the third basic sensor S3 Are arranged so that the β-axis negative region becomes the central axis, and the fourth basic sensor S4 is arranged so that the α-axis positive region becomes the central axis.

  This modification is an example in which the number of basic sensors in the first embodiment shown in FIG. 12 is changed from three to four, and the basic structure is the same as that of the first embodiment described in §3. It is. Therefore, as the reference numerals of the constituent elements in this modification, the reference numerals of the corresponding constituent elements in the first embodiment with “D” are used. The difference between the two is that in the first embodiment, the inner structure 200 is configured by a triangular prism as shown in FIG. 12, whereas the inner structure 200D of the modified example shown in FIG. 28 is configured by a square pole. The basic sensors S1 to S4 are provided on the four side surfaces, respectively.

  As shown in the figure, the inner structure 200D is configured by a square column having a square cross section, and a cylindrical outer structure 100D is disposed outside the inner structure 200D, and an outer shell structure is formed outside the cylindrical outer structure 100D. A body 300D is arranged. The rest of the configuration is the same as that of the first embodiment described in §3.

  That is, the connecting member is constituted by a disk-like member that covers the upper opening of the outer shell structure 300D, and the upper surface of the inner structure 200D is joined to the lower surface of the connecting member. And this connection member makes integral structure with inner structure 200D and outer shell structure 300D. Further, a bottom plate member that covers the opening is formed below the outer structure 100D, and the bottom plate member is fixed to the pedestal. And the calculating means is comprised by the calculating circuit formed on the circuit board fixed to the upper surface of the baseplate member.

  The outer structure 100D and the outer shell structure 300D are concentric cylinders having the γ-axis as a common central axis, and a predetermined gap dimension is secured between them. The dimension of the gap is set to a dimension that can control the displacement of the outer shell structure 300D with respect to the outer structure 100D within an appropriate range, and a control structure that does not apply an excessive external force to the basic sensors S1 to S4. Is realized. In this modified example, the control structure including the control groove and the control protrusion is omitted, but a control structure including the control groove and the control protrusion may be added as needed.

  Four sets of inner connection points (indicated by black circles) are provided on each side surface of the quadrangular prism constituting the inner structure 200D. That is, an inner connection point Iα + is provided at the intersection point with the α-axis positive region, an inner connection point Iα− is provided at the intersection point with the α-axis negative region, and an inner point at the intersection point with the β-axis positive region. A connection point Iβ + is provided, and an inner connection point Iβ− is provided at the intersection point with the β-axis negative region. On the other hand, four sets of outer connection points (indicated by white circles) are provided at opposing positions on the inner peripheral surface of the outer structure 100D. In other words, the outer connection point Jα + is provided at the intersection position with the α-axis positive region, the outer connection point Jα− is provided at the intersection position with the α-axis negative region, and the outer connection point Jα− is provided at the intersection position with the β-axis positive region. A connection point Jβ + is provided, and an outer connection point Jβ− is provided at the intersection point with the β-axis negative region.

  As shown in the figure, the four sets of basic sensors S1 to S4 fulfill a connecting function for connecting these inner connection points and outer connection points. Each of the basic sensors S1 to S4 is configured by the basic sensor S shown in FIG. 1, and detects a deformation function that is elastically deformed by the action of an external force and a moment component generated by the applied external force in addition to the above-described connection function. And a detection function. The basic sensors S1 to S4 are the same sensor having the same detection sensitivity.

  Here again, an αβγ global coordinate system with the center point Q as the origin is defined for the entire force sensor, and an XYZ local coordinate system with the center position of the strain detection board as the origin O for each of the basic sensors S1 to S4. , Each of the basic sensors S1 to S4 can detect the moment component Mx around the X axis and the moment component My around the Y axis in the respective XYZ coordinate systems. However, in the case of the first embodiment shown in FIG. 12, the Z axes of the three sets of basic sensors S1 to S3 are arranged along the β axis, the δ axis, and the ε axis so as to form 120 ° from each other. On the other hand, in the modification shown in FIG. 28, the β-axis negative direction, the α-axis positive direction, and the β-axis positive direction so that the Z axes of the four sets of basic sensors S1 to S4 form 90 ° with each other. Are arranged along the negative direction of the α-axis. In other words, the Z-axis positive direction of each of the basic sensors S1 to S4 is directed toward the origin Q.

  Specifically, the Z-axis positive direction defined for the first basic sensor S1 matches the β-axis negative direction, and the Z-axis positive direction defined for the second basic sensor S2 matches the α-axis positive direction. The Z-axis positive direction defined for the third basic sensor S3 matches the β-axis positive direction, and the Z-axis positive direction defined for the fourth basic sensor S4 matches the α-axis negative direction. Further, as in the case of the first embodiment shown in FIG. 14, the Y-axis positive direction for each of the basic sensors S1 to S4 is defined as the vertical downward direction (the direction toward the back side of the paper surface), and the X-axis positive direction. The direction is defined as a tangential direction counterclockwise with respect to a circle centered on the origin Q.

  Eventually, in the case of this modification, the moment component Mx around the X axis and the moment component My around the Y axis are detected from each of the four sets of basic sensors S1 to S4. Based on this, it is possible to calculate 6-axis components in the αβγ coordinate system of the applied external force. In the case of the first embodiment, six-axis components are obtained by the calculation based on the calculation formula shown in FIG. 22, whereas in the modification shown here, the six-axis component is calculated by the calculation based on the calculation formula shown in FIG. Ingredients can be obtained.

That is, the calculation means of the force sensor according to this modified example uses Mx1 as the moment component around the X axis detected by the first basic sensor S1, and My1 as the moment component around the Y axis as detected by the first basic sensor S1. The moment component around the X axis detected by the second basic sensor S2 is Mx2, the moment component around the Y axis detected by the second basic sensor S2 is My2, and the moment component around the X axis detected by the third basic sensor S3 is The moment component Mx3, the moment component around the Y axis detected by the third basic sensor S3 is My3, the moment component around the X axis detected by the fourth basic sensor S4 is detected by Mx4, and the fourth basic sensor S4 When the moment component around the Y-axis is My4, Fα = K2 using predetermined coefficient values K21, K22, K23, K24, K25, K26 (-My1 + My3)
Fβ = K22 (−My2 + My4)
Fγ = K23 (Mx1 + Mx2 + Mx3 + Mx4)
Mα = K24 (Mx1-Mx3)
Mβ = K25 (Mx2-Mx4)
Mγ = K26 (My1 + My2 + My3 + My4)
It is possible to detect six components of force components Fα, Fβ, Fγ and moment components Mα, Mβ, Mγ.

  In addition, the 6-axis component obtained by the above arithmetic expression becomes an independent detection value free from other-axis interference, as in the first embodiment. Here, although the individual explanation about the reason why the detection value of each axis component is obtained by the above arithmetic expression and the reason why the interference of other axis components can be eliminated is omitted, the first embodiment described in detail in §4 is omitted. Based on this detection operation, it can be easily understood that the 6-axis component free from other-axis interference can be obtained by the above calculation formula.

  Calculation formula shown in FIG. 22 (calculation formula when three sets of basic sensors are arranged every 120 °) and calculation formula shown in FIG. 29 (calculation formula when four sets of basic sensors are arranged every 90 °) As can be seen from the above, the former is an expression in which each term is multiplied by a coefficient value including a root operation, whereas the latter is only a simple addition / subtraction. Therefore, the modification in which four sets of basic sensors are arranged every 90 ° has an advantage that the calculation load of the calculation means is reduced. However, as compared with the modified example in which three sets of basic sensors are arranged at intervals of 120 °, the number of basic sensors is increased, resulting in a disadvantage that the apparatus is increased in size and cost.

  As described above, based on the first embodiment described in §3 and §4, the modification in which the number of basic sensors to be used is increased from 3 to 4 has been described. Also in the second to fourth embodiments, the number of basic sensors can be changed from three to four.

  For example, in the third embodiment, an example in which a triangular pyramid-shaped inner structure 200B as shown in FIG. 24 is used has been described. However, the inner structure is a quadrangular pyramid having a square cross section (so-called pyramid type). And connecting each of the inner connection points and the outer connection points provided at the opposing positions of the outer structure by four sets of basic sensors. A modification in which the number of basic sensors of the third embodiment is increased from 3 to 4 can be realized.

  In this case, the four basic sensors are arranged with the central axis (Z-axis) inclined by an inclination angle θ with respect to the αβ plane, but the projection lines obtained by projecting these central axes on the αβ plane are , Located on the α-axis or β-axis. As described above, in the modification in which the central axes (Z-axis) of the four sets of basic sensors are inclined by the inclination angle θ, the calculation means is not the calculation expression shown in FIG. 29 but includes a trigonometric function of the angle θ. Although it is necessary to perform a calculation using a complicated arithmetic expression, the degree of freedom in device design increases, so that it becomes easy to meet demands for suppressing the height or suppressing the size of the diameter.

  Of course, the number of basic sensors to be used is not limited to three or four, and a configuration using five or more basic sensors may be employed. However, the larger the number of basic sensors, the larger the device and the higher the cost. Therefore, it is actually preferable to use three or four basic sensors. In general, it is sufficient to use three sets of basic sensors to stably support the inner structure by the outer structure so that the inner structure can be freely displaced. Therefore, in practice, an embodiment using three sets of basic sensors is optimal. It can be said.

  The basic sensor constituting the force sensor according to the present invention has a connecting function for connecting the outer connection point and the inner connection point, but the position of the outer connection point and the position of the inner connection point have hitherto been It is not limited to the positions shown in the embodiments and modifications described above.

  However, practically, as in the first to third embodiments, when a columnar structure is used as the inner structure, the connecting line connecting the outer connection point and the inner connection point is the inner structure. Each of the basic sensors is arranged so as to be orthogonal to the outer surface of the columnar structure that forms the structure, and concentric cylindrical structures are used as the inner structure and the outer structure as in the fourth embodiment. When used, it is preferable to arrange each basic sensor so that a connecting line connecting the outer connection point and the inner connection point is orthogonal to the common central axis of the outer structure and the inner structure. If such an arrangement is adopted, the Z-axis of each basic sensor can be arranged radially outward with the γ-axis or origin G of the αβγ coordinate system as the center, and the calculation processing by the calculation means is further simplified. The effect to do.

<8.2 Modification regarding structure of basic sensor mounting part>
In §3, the structure of the first embodiment shown in FIGS. 12 and 13 has been described. In the first embodiment, the outer structure 100 is a cylindrical structure, and the force receiving bodies 30 of the three basic sensors S1 to S3 are fixed to the inner peripheral surface of the outer structure 100. . On the other hand, in §4, the detection operation according to the first embodiment has been described. In particular, in the description with reference to FIG. 19, the detection operation when the moment + Mβ around the β axis is applied to the inner structure 200 has been described.

  In the detection operation shown in FIG. 19, the moment + Mβ around the β axis is also applied to the first basic sensor S1, but the basic sensor S shown in FIG. When the surrounding moment component Mz acts, it is not necessarily flexible enough to cause sufficient deformation. That is, as shown in the side view of FIG. 1 (b), the upper and lower ends of the connecting member 20 are connected to the central portions of the diaphragm portions 11 and 31, and therefore this basic sensor S is exemplified in FIGS. Such deformation is likely to occur. However, even if a moment Mz around the Z axis is applied to the diaphragm portions 11 and 31, sufficient deformation does not necessarily occur. Accordingly, as shown in FIG. 19, when a moment + Mβ around the β axis is applied to the inner structure 200 of the force sensor, the first basic sensor S1 is sufficiently deformed around the β axis. May not be able to be performed, and deformation that occurs in the second and third basic sensors S2 and S3 may be suppressed and detection sensitivity may be reduced.

  In the first place, the basic sensor S shown in FIG. 1 is a sensor that detects a moment Mx around the X axis, a moment My around the Y axis, and a force Fz in the Z axis direction, and therefore detects when these moments or forces are applied. However, when the moment Mz around the Z-axis is applied, sufficient deformation does not necessarily occur. On the other hand, when the basic sensor S is used for the force sensor according to the present invention, for example, as shown in FIG. 19, for detecting the moment Mβ around the β axis, at least the first basic sensor S1 is It is preferable to have a structure in which sufficient deformation occurs when the moment Mz about the Z-axis acts.

  One method of providing the basic sensor S shown in FIG. 1 with flexibility about the Z-axis is to process the connection member 20 so that the base sensor S is easily deformed in the direction of twisting about the Z-axis. is there. However, this method has a problem that the structure of the connecting member 20 becomes complicated and the manufacturing cost increases. Another method is to extend the entire length of the connecting member 20. When the connecting member 20 is made of a general metal, a certain amount of elastic deformation occurs. Therefore, the longer the overall length, the easier the deformation in the twisting direction occurs. However, if the total length of the connecting member 20 is increased, the diameter of the force sensor according to the present invention must be increased, and the size cannot be reduced.

  The modification described here proposes a method for solving such a problem, and its feature is equivalent to that of the outer structure side instead of giving the basic sensor S itself flexibility around the Z axis. The structure is to provide a function. FIG. 30 is a perspective view showing an outer structure 100E corresponding to a modification of the outer structure 100 of the force sensor according to the first embodiment. For convenience of explanation, FIG. 30 shows a state in which three sets of basic sensors S1 to S3 (drawn by broken lines in the figure) are arranged inside the outer structure 100E. Actually, in order to configure the force sensor according to the first embodiment, the triangular prism-shaped inner structure 200 and the outer structure 100E further disposed inside the three sets of basic sensors S1 to S3. Although components such as the outer shell structure 300 disposed on the outside are necessary, in FIG. 30, illustration of other components is omitted for convenience of explanation.

  The outer structure 100E shown in FIG. 30 is a cylindrical structure similar to the outer structure 100 described in §3, but a wall portion through slit that penetrates from the outside to the inside at a predetermined portion of the wall portion. The portion surrounded by the wall portion through slit constitutes the basic sensor mounting portion. Specifically, in the example shown in FIG. 30, three sets of basic sensor attachment portions 160, 170, and 180 are formed on the outer structure 100E.

  Here, the first basic sensor mounting portion 160 is a circular portion in the vicinity of the outer connection point where the outer structure 100E and the β-axis intersect, and inside the first basic sensor S1 as indicated by a broken line. Is attached. Similarly, the second basic sensor mounting portion 170 is a circular portion in the vicinity of the outer connection point where the outer structure 100E and the γ-axis intersect, and inside the second basic sensor S2 as shown by a broken line. Is attached. The third basic sensor mounting portion 180 is a circular portion in the vicinity of the outer connection point where the outer structure 100E and the ε-axis intersect, and inside the third basic sensor S3, as shown by a broken line, It is attached.

  As shown in the front of FIG. 30, the third basic sensor mounting portion 180 is a disk-shaped member having a circular outline (strictly speaking, a curved disk-shaped member constituting a part of a cylinder). There are provided four sets of wall-shaped through slits SL1 to SL4 around the arc. Further, beam portions 181 to 184 are formed between a pair of adjacent wall portion through slits. Specifically, a beam portion 181 is formed between the wall portion through slits SL1 and SL2, and a beam portion 182 is formed between the wall portion through slits SL2 and SL3, and between the wall portion through slits SL3 and SL4. A beam portion 183 is formed, and a beam portion 184 is formed between the wall portion through slits SL4 and SL1.

  Eventually, the third basic sensor mounting portion 180 is surrounded by four sets of wall portion through slits SL1 to SL4 and is supported from the periphery by the four sets of beam portions 181 to 184. Here, the four sets of beam portions 181 to 184 are structures made of the same material (for example, an aluminum alloy) as the main body portion of the outer structure 100E. However, since the thickness is small, sufficient flexibility for deformation is provided. Have. For this reason, the third basic sensor mounting portion 180 is displaced with respect to the main body portion of the outer structure 100E within a predetermined degree of freedom by the action of an external force (for example, a displacement that is twisted around the ε axis). Or displacement of the ε-axis in the axial direction). The same applies to the first and second basic sensor attachment portions 160 and 170.

  As described above, in the modification shown in FIG. 30, the vicinity of the outer connection point (intersection with the β axis, γ axis, and ε axis) of the outer structure 100E constitutes the basic sensor mounting portion 160, 170, 180. Each basic sensor S1, S2, S3 is mounted inside these basic sensor mounting portions 160, 170, 180. In addition, around the basic sensor attachment portions 160, 170, 180, a plurality of wall portion through slits (SL1 to SL4, etc.) penetrating the wall portion of the outer structure 100E along the outline of each basic sensor attachment portion. Are provided, and flexible beam portions (181 to 184, etc.) are formed between adjacent through-wall slits. As a result, the basic sensor mounting portions 160, 170, and 180 are supported by these beam portions from the periphery.

  In particular, in the case of the modification illustrated in FIG. 30, each of the basic sensor mounting portions 160, 170, and 180 has a circular contour line, and four sets of arc-shaped wall through slits along the contour line. (SL1 to SL4 etc.) are provided, and a total of four beam parts are formed by arranging flexible beam parts (181 to 184 etc.) between the adjacent wall through slits. Each of the sensor mounting portions 160, 170, and 180 is supported by a total of four beam portions from the periphery.

  In the modification shown in FIG. 30, sufficient detection sensitivity can be secured even in the moment Mβ detection operation shown in FIG. That is, even if the three basic sensors S1 to S3 themselves do not have sufficient flexibility around the Z axis, the basic sensor mounting portions 160, 170, and 180 can be moved around the Z axis of each basic sensor (β 19), the displacement is not suppressed by the first basic sensor S1 even in the detection operation shown in FIG. Detection values having sufficient sensitivity can be obtained from the third basic sensors S2 and S3.

  Note that the modification shown in FIG. 30 is also advantageous when providing a control structure so that excessive external force does not act on each of the basic sensors S1 to S3. As shown in FIG. 12, the first embodiment is provided with a control structure comprising a combination of control protrusions 311, 312, 313 and control grooves 111, 112, 113, and the distance between the two is a predetermined dimension. By performing such a design, the basic sensors S1 to S3 can be protected from damage.

  For example, in the case of the basic sensor S shown in FIG. 1, when a force + Fz in the Z-axis direction is applied, deformation as shown in FIG. 7 occurs. In the case of the basic sensor prototyped by the inventor of the present application, the displacement of the central portions of the diaphragm portions 11 and 31 when a rated load with respect to the force Fz in the Z-axis direction is applied is about 5 μm (basic using a piezoresistive element) The sensor can sufficiently detect such a displacement). In this case, the displacement in the Z-axis direction at the rated load is about 10 μm in total. Here, for example, in order to control the displacement when an external force more than five times the rated load is applied, a control structure that suppresses the displacement amount in the Z-axis direction to 50 μm or less is required. In other words, in the case of the structure shown in FIG. 12, it is necessary to set the distance between each control protrusion 311, 312, 313 and the bottom surface of each control groove 111, 112, 113 to 50 μm. However, in practice, in order to perform a process in which the distance between the control protrusion and the control groove is about 50 μm, a highly accurate processing technique is required, which is not an easy operation.

  On the other hand, if the structure shown in the modified example of FIG. 30 is adopted, the basic sensor mounting portions 160, 170, 180 themselves are displaced in the Z-axis direction (β-axis, γ-axis, ε-axis direction). An effect of apparently amplifying the displacement amount of the sensors S1 to S3 in the Z-axis direction is obtained. Since this apparent amplification factor is determined according to the vertical, horizontal, and length dimension values of the beam portion, it can be obtained by creating a prototype or using a technique of FEM analysis. For example, if the amplification factor thus obtained is 4, the distance between the control protrusion and the control groove may be set to 50 μm × 4 = 200 μm, and the ease of processing is remarkably improved. .

  As described above, in the first embodiment shown in FIGS. 12 and 13, the modification in which the slit and the beam structure are employed in the wall portion of the cylindrical outer structure and the basic sensor mounting portion is displaced has been described. Such a modification can be similarly applied to the second to fourth embodiments.

<8.3 Modification of Basic Sensor Structure>
All of the three sets of basic sensors S1 to S3 shown in the first to third embodiments are constituted by the basic sensor S shown in FIG. 1, and the three sets of basic sensors S1 ′ to S1 ′ shown in the fourth embodiment. S3 'is a partial modification of the basic sensor S shown in FIG. 1 (replacement of the connecting member 20 and the force receiving body 30 with the hook-shaped portions 21 to 23). As described above, the basic sensor S shown in FIG. 1 has excellent detection sensitivity of the moments Mx and My, and as far as the inventor of the present application knows, the basic sensor S is an optimal sensor for use in the force sensor according to the present invention.

  The main components of the basic sensor S shown in FIG. 1 are a force receiving body 30 that receives an applied external force, a strain generating body 10 that has a diaphragm portion 11 that deforms based on the force received by the force receiving body 30, and a force receiving body. 30 and a connecting member 20 that connects the diaphragm section 11, a detection element A that detects distortion of the diaphragm section 11, and a detection circuit that outputs moment components Mx and My as electrical signals based on the detection result of the detection element A As the detection element A, as shown in FIG. 8, piezoresistive elements A1 to A8 that detect the distortion of the diaphragm portion 11 as a change in resistance value are used.

  More specifically, in the case of the basic sensor S shown in FIG. 1, the strain generating body 10 is configured by a plate-like member having an upper surface and a lower surface parallel to the XY plane, and is formed at the center of the upper surface of the strain generating body 10. In the defined detection region, a detection groove G1 is formed toward the lower surface side. And the diaphragm part 11 is formed by the bottom part of this detection groove | channel G1, and the side wall part 12 is formed in the circumference | surroundings of this detection groove | channel G1, and the lower surface of the diaphragm part 11 and the lower surface of the side wall part 12 are on the same plane. The structure is located.

  On the other hand, the force receiving body 30 is disposed below the strain body 10 at a predetermined interval, the connecting member 20 is constituted by a columnar member disposed on the Z axis, and the upper end thereof is the center of the lower surface of the diaphragm portion 11. The lower end is connected to the center of the upper surface of the force receiving body 30.

  Further, the strain detection substrate 40 is bonded to the bottom surface of the detection groove G1 (the top surface of the diaphragm portion 11). The strain detection substrate 40 is disposed at the position of the origin O of the XYZ three-dimensional orthogonal coordinate system, the upper surface and the lower surface form a surface parallel to the XY plane, and the stress generated by the deformation of the diaphragm portion 11 is transmitted. It is joined to the upper surface of the diaphragm part 11. As shown in FIG. 8, piezoresistive elements A1 to A8 are formed at predetermined positions on the upper surface of the strain detection substrate 40, and the detection circuit formed on the circuit board 50 includes these piezoresistive elements. Based on the change in electric resistance of A1 to A8, an electric signal indicating the moment components Mx and My is output.

  As described above, the basic sensor S shown in FIG. 1 is a sensor having a function of detecting distortion of the diaphragm portion 11 by the piezoresistive elements A1 to A8 and outputting electric signals indicating the moment components Mx and My. A piezoresistive element is not necessarily used as a detection element that detects the distortion of the diaphragm section 11. For example, instead of the piezoresistive element, a capacitive element that detects the displacement of the diaphragm portion as a change in the capacitance value can be used as the detection element.

  FIG. 31 is a side view showing an example of a basic sensor using a capacitive element. As shown in the figure, this basic sensor includes a disk-shaped auxiliary substrate 60, a disk-shaped strain generating body 70, a columnar connection member 80, a disk-shaped force receiving body 90, and a Z-axis as a common central axis. Are arranged and connected to each other.

  The auxiliary substrate 60 is a simple disk-shaped substrate, and a disk-shaped common fixed electrode E0 is formed at the center of the lower surface thereof. The strain-generating body 70 is a structure similar to the strain-generating body 10 of the basic sensor S shown in FIG. 1, and a detection groove G3 is dug in a circular region on the upper surface, and the bottom surface of the detection groove G3. Is a thin diaphragm portion 71 and its periphery constitutes a side wall portion 72. On the other hand, the force receiving body 90 is a structure similar to the force receiving body 30 of the basic sensor S shown in FIG. 1, and a detection groove G4 is dug in a circular region on the lower surface, and this detection groove G4. The bottom surface of FIG. 1 constitutes a thin diaphragm portion 91 and the periphery thereof constitutes a side wall portion 92. The columnar connection member 80 fulfills the function of connecting the central portion of the diaphragm portion 71 and the central portion of the diaphragm portion 91.

  32 is a top view of the strain body 70 in the basic sensor shown in FIG. As described above, the circular detection groove G <b> 3 is dug on the upper surface of the strain generating body 70, and a thin disk-shaped diaphragm portion 71 is formed on the bottom surface thereof. And on the upper surface of this diaphragm part 71, as shown in the figure, four fan-shaped individual displacement electrodes E1 to E4 are formed. When the origin O of the XYZ coordinate system is defined at the illustrated position, the X axis is defined in the right direction of the figure, and the Y axis is defined in the upward direction, the electrode E1 is disposed in the X axis positive region and the electrode E2 is in the Y axis positive region. The electrode E3 is disposed in the X-axis negative region, and the electrode E4 is disposed in the Y-axis negative region. Since these four individual displacement electrodes E1 to E4 are formed on the upper surface of the diaphragm portion 71 that is deformed by the action of the external force, they are displaced by the action of the external force.

  On the other hand, the common fixed electrode E0 formed on the lower surface of the auxiliary substrate 60 is a single circular electrode facing the whole of the four individual displacement electrodes E1 to E4, and the influence of the deformation of the diaphragm portion 71 is reduced. It is an electrode which maintains a fixed state without receiving. Here, when the electrostatic capacitance elements constituted by the four individual displacement electrodes E1 to E4 and the fan-shaped partial region of the common fixed electrode E0 facing them are referred to as capacitance elements C1 to C4, respectively. The distance between the counter electrodes constituting each of the capacitive elements C1 to C4 changes due to the deformation of the diaphragm portion 71, and as a result, the capacitance values of the capacitive elements C1 to C4 vary.

  Therefore, if a change in the capacitance value of each of the capacitive elements C1 to C4 is electrically detected, the deformation mode of the diaphragm portion 71 can be recognized based on the detection result, and the auxiliary substrate 60 and the power receiving body can be recognized. In a state where one of 90 is fixed, an external force acting on the other can be detected. Specifically, the moment component Mx around the X axis can be obtained as a difference between the capacitance values of the capacitive elements C2 and C4, and the moment component My around the Y axis can be obtained from the capacitances of the capacitive elements C1 and C3. It can be obtained as a difference in values. Since such a detection principle is a known technique disclosed in, for example, Japanese Patent No. 2841240, detailed description thereof is omitted here.

  Finally, instead of the basic sensor S (sensor using a piezoresistive element as a detection element) shown in FIG. 1, the basic sensor (sensor using a capacitive element as a detection element) shown in FIG. 31 may be used. It is possible to constitute a force sensor according to the above. As described above, the basic sensor used in the force sensor according to the present invention is not limited to the basic sensor shown in FIG. 1, and may be a sensor having a different structure or a different detection principle.

  In short, the basic sensor used for the force sensor according to the present invention includes the origin O located on the connecting line connecting the outer connecting point and the inner connecting point, the Z axis arranged on the connecting line, and the Z axis. When an XYZ three-dimensional orthogonal coordinate system having an X axis orthogonal to each other and a Y axis orthogonal to both the Z axis and the X axis is defined, the moment component Mx around the X axis of the applied external force or around the Y axis As long as it has a detection function for detecting the moment component My, the substance structure may be anything.

  In the basic sensor S shown in FIG. 1, the detection groove G2 is also formed on the force receiving body 30 side to form a diaphragm portion 31, and in the basic sensor shown in FIG. 31, the force receiving body 90 side is also formed. Although the detection groove G4 is dug to form the diaphragm portion 91, the diaphragm portions 31 and 91 on the force receiving bodies 30 and 90 side are not essential. That is, the diaphragm portions 11 and 71 formed by the detection grooves G1 and G3 dug on the strain-generating bodies 10 and 70 side are necessary for electrically detecting the bending caused by the action of the external force. Since the diaphragms 31 and 91 on the force receiving bodies 30 and 90 side are not directly used for such detection, the detection grooves G2 and G4 on the force receiving bodies 30 and 90 side are omitted. It doesn't matter.

  However, if the detection grooves G2 and G4 are dug in the force receiving bodies 30 and 90 and the diaphragm portions 31 and 91 are formed, the diaphragm portions 11 and 71 that are directly used for detecting the external force are used. Thus, it becomes possible to cause the deflection more effectively, and the detection sensitivity can be improved. Therefore, in practice, it is preferable to form the diaphragm portions 31 and 91 by digging the detection grooves G2 and G4 on the force receiving bodies 30 and 90 side as in the examples shown in FIGS. .

  Further, in the basic sensor S shown in FIG. 1 and the basic sensor shown in FIG. 31, each diaphragm portion is configured by a thin disk-shaped film, but the diaphragm portion is not necessarily configured by a film-like structure. For example, each diaphragm part may be configured by a cross-shaped beam structure. The same applies to the diaphragm portions 131 to 133 in the fourth embodiment shown in FIG. In short, the diaphragm portion in the present application does not need to be a general film-like structure, and may be formed of any structure as long as it is a flexible member having a function of elastic deformation.

<8.4 Other Modifications>
As mentioned above, although the force sensor which concerns on this invention was demonstrated about the 1st-4th embodiment and also some modifications were described, the matter described so far can be used combining freely. Is possible. For example, the control mechanism using the control protrusion and the control groove described in the first embodiment can be employed in other embodiments and modifications.

  In the embodiment described so far, the strain sensor 10 side of the basic sensor S is connected to the inner structure body, and the force receiving body 30 side is connected to the outer structure body. In the fixed state, it has a function of detecting moment components Mx and My of the external force acting on the other end, so that the force sensor 30 side of the basic sensor S is connected to the inner structure in the reverse direction. The strain generating body 10 side may be connected to the outer structure for use.

  Similarly, the force sensor itself according to the present invention also has a function of detecting an external force applied to the other of the outer structure and the inner structure in a state where one is fixed. In the embodiment, it can be used for detecting an external force applied to the outer shell structure 300 in a state where the base 400 is fixed, and conversely, in the state where the outer shell structure 300 is fixed, It can also be used for detecting the applied external force.

  In the embodiments described so far, in the αβγ coordinate system, the six-axis components of the applied external force, that is, the force component Fα acting in the α-axis direction, the force component Fβ acting in the β-axis direction, and acting in the γ-axis direction. A force sensor having a function of detecting all six components of the force component Fγ, the moment component Mα acting around the α axis, the moment component Mβ acting around the β axis, and the moment component Mγ acting around the γ axis As described above, the force sensor according to the present invention does not necessarily have a function of detecting all of these six-axis components, and it is sufficient that at least one of these six-axis components can be detected. .

  In other words, depending on the use of the force sensor, it may be sufficient to detect only a part of the six-axis components, but not all of the six-axis components. It is enough if it is provided. Therefore, the calculation means does not need to have a calculation function for obtaining all six-axis components based on the calculation formulas as shown in FIG. 22 and FIG. 29, and has a calculation function for necessary components according to the application. It is enough if you have it. In addition, if a specific moment detection value of a specific basic sensor becomes unnecessary as a result of omitting the detection function of some components, the detection function of the specific moment detection value by the basic sensor may be omitted. it can. Therefore, each basic sensor does not necessarily need to have a function of detecting both moment components Mx and My, and may have a function of detecting at least one of them.

  In short, the force sensor according to the present invention has a configuration in which at least a part of the inner structure is accommodated in the outer structure, and a plurality of n sets (however, n ≧ 3) are connected between the two, The moment component detected by the basic sensor may be calculated to detect the force component in the arbitrary coordinate axis direction and the moment component around the arbitrary coordinate axis as desired. By doing so, it becomes possible to detect an external force component according to a demand while achieving downsizing and cost reduction with a relatively simple structure.

  However, even if the detection function for some of the six-axis components is omitted, it is not possible to achieve a significant cost reduction. Therefore, in practice, as in the embodiment described above and its modifications. It is preferable to configure a force sensor having a function of detecting all the six-axis components of the force component in each coordinate axis direction of the three-dimensional αβγ coordinate system and the moment component around each coordinate axis.

10: Strain body 11: Diaphragm part 12: Side wall part 15: Screw hole (through hole for screw insertion)
18: Cover 19: Cover bonding part 20: Connection member 21-23: Hook 30: Power receiving body 31: Diaphragm part 32: Side wall part 33: Opening part 35: Screw hole (internal thread forming hole)
40: Strain detection board 47: Bonding wire 50: Circuit board 60: Auxiliary board 70: Strain body 71: Diaphragm part 72: Side wall part 80: Connection member 90: Power receiving body 91: Diaphragm part 92: Side wall part 100, 100A , 100B, 100C, 100D, 100E: outer structures 111, 112, 113: control grooves 121, 122, 123: mounting grooves 131, 132, 133: diaphragm portions 150, 150B: bottom plate member 150C: top plate member 160: first 1 basic sensor mounting portion 170: second basic sensor mounting portion 180: third basic sensor mounting portions 181 to 184: beam portions 200, 200A, 200B, 200C, 200D: inner structures 211, 212, 213: insertion Holes 250, 250B: Connecting member 250C: Bottom plate member 270: Cover plate member 280: Filled with silicon rubber 300, 300B, 300C, 300D: outer shell structures 311, 312, 313: control protrusion 350C: connecting member 400, 400A, 400B, 400C, 400D: pedestal 500, 500A, 500B, 500C, 500D: circuit board A, A1 A8: Piezoresistive element E: DC power supply E0: Common fixed electrode E1-E4: Individual displacement electrode Fz: Force component in the Z-axis direction Fα: Force component in the α-axis direction Fβ: Force component in the β-axis direction Fγ: γ-axis Directional force component f1: Contour line of detection groove (detection region) f2: Outer contour lines G1 to G4 of cover adhesion portion: Detection grooves Iβ, Iδ, Iε, Iθ: Inner connection points Iα +, Iα−, Iβ + , Iβ−: Inner connection points Jβ, Jδ, Jε, Jθ: Outer connection points Jα +, Jα−, Jβ +, Jβ−: Inner connection points K11 to K26: Coefficients used for calculation Mx: Moment component around the X axis Mx1: Moment component around X axis detected by basic sensor S1 Mx2: Moment component around X axis detected by basic sensor S2 Mx3: Moment component around X axis detected by basic sensor S3 My: Around Y axis Moment component My1: moment component around the Y axis detected by the basic sensor S1 My2: moment component around the Y axis detected by the basic sensor S2 My3: moment component around the Y axis detected by the basic sensor S3: Moment component around α axis Mβ: Moment component around β axis Mγ: Moment component around γ axis N: Screw O, O1, O2, O3: Origin of XYZ three-dimensional orthogonal coordinate system Q: αβγ Three-dimensional orthogonal coordinate system Origin S: Basic sensors S1, S1 ′: First basic sensors S2, S2 ′: 2 basic sensors S3, S3 ': 3rd basic sensor S4: 4th basic sensor SL1-SL4: Wall part penetration slits Tx1, Tx2: Output terminal Ty1, Ty2 of moment component Mx: Output terminal Vx of moment component My : Output voltage Vy corresponding to moment component Mx: output voltage W corresponding to moment component My: cutting line X: coordinate axis of XYZ three-dimensional orthogonal coordinate system Y: coordinate axis of XYZ three-dimensional orthogonal coordinate system Z: XYZ three-dimensional orthogonal coordinate Coordinate axis of system α: αβγ Coordinate axis of 3D Cartesian coordinate system β: Coordinate axis of αβγ 3D Cartesian coordinate system γ: Coordinate axis of αβγ 3D Cartesian coordinate system δ: Axis on αβ plane (210 ° with respect to α axis) axis)
ε: axis on αβ plane (axis forming 330 ° with respect to α axis)
θ: Inclination angle

Claims (36)

An outer structure having a receiving space inside;
An inner structure at least partially housed in the housing space;
A plurality of n sets (where n ≧ 3) of basic sensors;
A calculation means for performing calculation based on the outputs of the n sets of basic sensors;
With
Each of the n sets of basic sensors is
A connection function for directly or indirectly connecting an outer connection point provided at a predetermined position of the outer structure and an inner connection point provided at a predetermined position of the inner structure;
Deformation that elastically deforms so that the relative positional relationship between the outer connection point and the inner connection point changes based on an external force acting on the other of the outer connection point and the inner connection point in a fixed state. Function and
An origin O located on a connecting line connecting the outer connecting point and the inner connecting point, a Z-axis disposed on the connecting line, an X-axis orthogonal to the Z-axis, the Z-axis and the X-axis A detection function for detecting at least one of the moment component Mx around the X axis and the moment component My around the Y axis of the external force when an XYZ three-dimensional orthogonal coordinate system having a Y axis orthogonal to both is defined; Have
The calculation means performs a calculation using a detection value detected by each of the n sets of basic sensors, whereby the outer structure and the inner structure have a force acting on the other in a state where one is fixed or A force sensor characterized by detecting a moment or both. The force sensor according to claim 1,
The outer structure is configured by a cylindrical structure that accommodates all or part of the inner structure therein, and each basic sensor is connected to the outer connection point on the inner peripheral surface of the cylindrical structure and the inner side. A force sensor characterized by connecting an inner connection point on an outer peripheral surface of a structure. The force sensor according to claim 2,
An outer shell structure provided on the outer side of the outer structure and made of a cylindrical structure; and
A connecting member for connecting the outer shell structure and the inner structure;
A force sensor further comprising: The force sensor according to claim 3, wherein
When the outer shell structure is arranged so that its central axis is directed in the vertical direction, a connecting member is constituted by a plate-like member covering the upper opening, and the outer shell structure is formed around the lower surface of the plate-like member. A force sensor, characterized in that the body is joined and the upper surface of the inner structure is connected to the center of the lower surface of the plate-like member. The force sensor according to claim 4,
When the outer structure and the outer shell structure are constituted by a concentric cylindrical structure having a common axis as a central axis, and the displacement of the inner structure with respect to the outer structure reaches a predetermined allowable range, The distance between the outer structure and the outer shell structure is set to a predetermined value so that the outer peripheral surface of the outer structure and the inner peripheral surface of the outer shell structure are in contact with each other, and further displacement is limited. Has been
A force sensor characterized in that each basic sensor performs a normal detection function as long as the displacement of the inner structure relative to the outer structure is within the allowable range. The force sensor according to claim 4 or 5,
The outer structure and the outer shell structure are constituted by a concentric cylindrical structure having a common axis as a central axis,
The inner peripheral surface of the outer shell structure is provided with a control projection directed inward, and the outer peripheral surface of the outer structure is provided with a control groove for accommodating the tip of the control protrusion, When the displacement of the inner structure relative to the outer structure reaches a predetermined allowable range, the tip portion of the control protrusion and the groove forming surface of the control groove come into contact with each other, and further displacement is limited. The distance between the tip of the control protrusion and the groove forming surface of the control groove is set to a predetermined value,
A force sensor characterized in that each basic sensor performs a normal detection function as long as the displacement of the inner structure relative to the outer structure is within the allowable range. The force sensor according to claim 4 or 5,
The outer structure and the outer shell structure are constituted by a concentric cylindrical structure having a common axis as a central axis,
The outer peripheral surface of the outer structure is provided with a control projection directed outward, and the inner peripheral surface of the outer shell structure is provided with a control groove that accommodates the tip of the control projection, When the displacement of the inner structure relative to the outer structure reaches a predetermined allowable range, the tip portion of the control protrusion and the groove forming surface of the control groove come into contact with each other, and further displacement is limited. The distance between the tip of the control protrusion and the groove forming surface of the control groove is set to a predetermined value,
A force sensor characterized in that each basic sensor performs a normal detection function as long as the displacement of the inner structure relative to the outer structure is within the allowable range. The force sensor according to any one of claims 2 to 7,
A bottom plate member that covers a lower opening of the outer structure when the outer structure is disposed so that a central axis thereof is directed in the vertical direction, and a circuit board fixed to the upper surface of the bottom plate member. The force sensor is constituted by an arithmetic circuit formed on the circuit board. The force sensor according to any one of claims 2 to 8,
The basic sensor is attached to the basic sensor mounting part that forms the vicinity of the outer connection point of the outer structure.
Around the basic sensor mounting portion, a plurality of wall through slits are provided through the wall of the outer structure along the outline of the basic sensor mounting portion, and between the adjacent wall through slits. A force sensor, wherein a flexible beam portion is formed, and the basic sensor mounting portion is supported by the beam portion from the periphery. The force sensor according to claim 9, wherein
The basic sensor mounting portion has a circular contour line, and four sets of arc-shaped wall through slits are provided along the contour, and the beam portions are arranged between the adjacent wall through slits. Thus, a total of four sets of beam portions are formed, and the basic sensor mounting portion is supported by the four sets of beam portions from the periphery. The force sensor according to any one of claims 1 to 10,
The inner structure is constituted by a columnar structure at least a part of which is accommodated in the outer structure, and each basic sensor includes an outer connection point on the inner peripheral surface of the outer structure and the columnar structure. A force sensor that connects an inner connection point on an outer peripheral surface of a body. The force sensor according to claim 11, wherein
The inner structure is constituted by a triangular prism having an equilateral triangular cross section,
Inner connection points are provided on each side of the triangular prism, and three sets of basic sensors each have a connecting function for connecting the inner connection points and the outer connection points provided at positions facing the outer structure. Force sensor characterized by. The force sensor according to claim 11, wherein
The inner structure is constituted by a triangular pyramid having an equilateral triangular cross section,
Each side face of the triangular pyramid is provided with an inner connection point, and three sets of basic sensors each have a connecting function for connecting each inner connection point and the outer connection point provided at the opposite position of the outer structure. A force sensor characterized by that. The force sensor according to claim 11, wherein
The inner structure is constituted by a quadrangular prism with a square cross section,
Inner connection points are provided on the respective side surfaces of the quadrangular prism, and four sets of basic sensors each have a connecting function for connecting the inner connection points and the outer connection points provided at the opposing positions of the outer structure. A force sensor characterized by that. The force sensor according to claim 11, wherein
The inner structure is constituted by a square pyramid with a square cross section,
Inner connection points are provided on the respective sides of the quadrangular pyramid, and four sets of basic sensors each have a connecting function for connecting the inner connection points and the outer connection points provided at opposite positions of the outer structure. A force sensor characterized by that. The force sensor according to any one of claims 11 to 15,
Force sensor characterized in that each basic sensor is arranged so that the connecting line connecting the outer connection point and the inner connection point is orthogonal to the outer surface of the columnar structure constituting the inner structure. . The force sensor according to claim 1,
The outer structure and the inner structure are each constituted by a cylindrical structure,
Defining a plurality of n straight lines penetrating the first sidewall of the outer structure, the first sidewall of the inner structure, the second sidewall of the inner structure, and the second sidewall of the outer structure; When these n straight lines are defined as reference lines corresponding to n sets of basic sensors,
An insertion hole is formed in each first side wall through which each reference line of the inner structure passes,
Each basic sensor has an outer connection point provided on the inner peripheral surface of the first side wall of the outer structure through which the corresponding reference line passes, and an inner side of the second side wall of the inner structure through which the corresponding reference line passes. A force sensor having a connection function of connecting an inner connection point provided on a peripheral surface through an insertion hole formed in a first side wall of an inner structure through which a corresponding reference line passes. The force sensor according to claim 17,
A force sensor, further comprising a top plate member that covers the upper opening when the outer structure is disposed so that the central axis thereof is directed in the vertical direction. The force sensor according to claim 18,
When the outer structure and the inner structure are constituted by concentric cylindrical structures having a common axis as a central axis, and the displacement of the outer structure with respect to the inner structure reaches a predetermined allowable range, the inner structure The distance between the inner structure and the outer structure is set to a predetermined value so that the outer peripheral surface of the structure is in contact with the inner peripheral surface of the outer structure and further displacement is limited. ,
A force sensor characterized in that each basic sensor performs a normal detection function as long as the displacement of the outer structure relative to the inner structure is within the allowable range. The force sensor according to claim 18 or 19,
When the outer structure and the inner structure are configured by a concentric cylindrical structure having a common axis as a central axis, and the displacement of the outer structure with respect to the inner structure reaches a predetermined allowable range, the inner structure The interval between the part of the basic sensor and the insertion hole is set to a predetermined value so that the insertion hole formed in the body contacts with a part of the basic sensor passing through the insertion hole and further displacement is limited. Is set,
A force sensor characterized in that each basic sensor performs a normal detection function as long as the displacement of the outer structure relative to the inner structure is within the allowable range. The force sensor according to claim 19 or 20,
A force sensor, wherein each basic sensor is arranged such that a connecting line connecting an outer connection point and an inner connection point is orthogonal to a common central axis of the outer structure and the inner structure. The force sensor according to any one of claims 17 to 21,
The vicinity of the intersection with the reference line of the first side wall of the outer structure constitutes a diaphragm portion that is thinner than the other portions, and one end of the basic sensor is joined to the diaphragm portion. Force sensor. The force sensor according to any one of claims 17 to 22,
A plurality of n sets of basic sensors each have a hook-shaped portion for performing a connection function, and at least some of the basic sensors can avoid contact with the hook-shaped portions of other basic sensors. Force sensor characterized by being curved like this. The force sensor according to any one of claims 17 to 23,
A bottom plate member that covers a lower opening of the inner structure when the inner structure is disposed such that a central axis thereof is directed in a vertical direction; and a circuit board fixed to the upper surface of the bottom plate member. The force sensor is constituted by an arithmetic circuit formed on the circuit board. The force sensor according to any one of claims 17 to 24,
An outer shell structure provided on the outer side of the outer structure and made of a cylindrical structure; and
A connecting member connecting the outer structure and the outer shell structure;
A force sensor further comprising: The force sensor according to any one of claims 1 to 11 and 17 to 25,
When defining an αβγ three-dimensional orthogonal coordinate system having an α axis, a β axis, and a γ axis orthogonal to each other at the origin Q defined inside the inner structure,
The Z axis of the XYZ three-dimensional orthogonal coordinate system defined for each basic sensor is defined in a direction passing through the origin Q,
The computing means includes a force component Fα acting in the α-axis direction, a force component Fβ acting in the β-axis direction, a force component Fγ acting in the γ-axis direction, a moment component Mα acting around the α-axis, the β A force sensor for detecting at least one of a moment component Mβ acting around an axis and a moment component Mγ acting around the γ-axis. The force sensor according to claim 26, wherein
Each X-axis and each Z-axis defined for each basic sensor are axes included in the αβ plane, and each Y-axis defined for each basic sensor is defined to be parallel to the γ-axis. A force sensor. The force sensor according to claim 27, wherein
A force sensor comprising three sets of basic sensors arranged so that each Z-axis forms 120 ° with respect to each other. The force sensor according to claim 28, wherein
On the αβ plane, an azimuth angle is defined with the α axis direction being 0 ° and the β axis direction being 90 °. Further, the δ axis facing the azimuth angle 210 ° direction and the azimuth angle 330 ° direction When we define the facing ε axis,
The Z-axis positive direction defined for the first basic sensor matches the β-axis negative direction, the Z-axis positive direction defined for the second basic sensor matches the δ-axis negative direction, and the third basic sensor Three basic sensors having the same detection sensitivity are arranged so that the defined Z-axis positive direction coincides with the ε-axis negative direction,
The computing means Mx1 the moment component around the X axis detected by the first basic sensor, My1 the moment component around the Y axis detected by the first basic sensor, and the X detected by the second basic sensor. The moment component around the axis is Mx2, the moment component around the Y axis detected by the second basic sensor is My2, the moment component around the X axis detected by the third basic sensor is Mx3, the third basic sensor When the moment component around the Y axis detected by is set to My3, Fα = K11 (−My1 + 1/2 · My2 + 1/2 · My3) using predetermined coefficient values K11, K12, K13, K14, K15, and K16
Fβ = K12 (−√3 / 2 · My2 + √3 / 2 · My3)
Fγ = K13 (Mx1 + Mx2 + Mx3)
Mα = K14 (Mx1-1 / Mx2-1 / Mx3)
Mβ = K15 (√3 / 2 · Mx2−√3 / 2 · Mx3)
Mγ = K16 (My1 + My2 + My3)
A force sensor that detects six components of force components Fα, Fβ, Fγ and moment components Mα, Mβ, Mγ by performing the following calculation. The force sensor according to claim 27, wherein
A force sensor comprising four sets of basic sensors arranged so that each Z-axis forms 90 ° with each other. The force sensor according to claim 30, wherein
The Z-axis positive direction defined for the first basic sensor matches the β-axis negative direction, the Z-axis positive direction defined for the second basic sensor matches the α-axis positive direction, and the third basic sensor Four sets of basic sensors having the same detection sensitivity so that the defined Z-axis positive direction matches the β-axis positive direction and the Z-axis positive direction defined for the fourth basic sensor matches the α-axis negative direction Is placed,
The computing means Mx1 the moment component around the X axis detected by the first basic sensor, My1 the moment component around the Y axis detected by the first basic sensor, and the X detected by the second basic sensor. The moment component around the axis is Mx2, the moment component around the Y axis detected by the second basic sensor is My2, the moment component around the X axis detected by the third basic sensor is Mx3, the third basic sensor When the moment component around the Y axis detected by is My3, the moment component around the X axis detected by the fourth basic sensor is Mx4, and the moment component around the Y axis detected by the fourth basic sensor is My4 Fα = K21 (−My1 + My3) using predetermined coefficient values K21, K22, K23, K24, K25, K26
Fβ = K22 (−My2 + My4)
Fγ = K23 (Mx1 + Mx2 + Mx3 + Mx4)
Mα = K24 (Mx1-Mx3)
Mβ = K25 (Mx2-Mx4)
Mγ = K26 (My1 + My2 + My3 + My4)
A force sensor that detects six components of force components Fα, Fβ, Fγ and moment components Mα, Mβ, Mγ by performing the following calculation. The force sensor according to claim 26, wherein
Each Z axis defined for each basic sensor points in a direction that makes an inclination angle θ with respect to the αβ plane, and each Y axis that is defined for each basic sensor indicates a direction that makes an inclination angle θ with respect to the γ axis. A force sensor characterized in that each basic sensor is arranged to face. The force sensor according to any one of claims 1 to 32,
Each basic sensor receives a force receiving body that receives the applied external force, a strain generating body having a diaphragm section that deforms based on the force received by the force receiving body, and a connection that connects the force receiving body and the diaphragm section. A force that includes a member, a detection element that detects distortion of the diaphragm portion, and a detection circuit that outputs at least one of moment components Mx and My as an electrical signal based on a detection result of the detection element. Sense sensor. The force sensor according to claim 33,
A force sensor using a piezoresistive element that detects a distortion of a diaphragm portion as a change in resistance value as a detecting element. The force sensor according to claim 34, wherein
The strain body is constituted by a plate-like member having an upper surface and a lower surface parallel to the XY plane, and the detection region defined in the center of the upper surface of the strain body has a detection groove toward the lower surface side. The diaphragm portion is formed by the bottom portion of the detection groove, and a side wall portion is formed around the detection groove. The lower surface of the diaphragm portion and the lower surface of the side wall portion are on the same plane. Position to,
The force receiving body is disposed at a predetermined interval below the strain body,
The connection member is constituted by a columnar member arranged on the Z axis, the upper end thereof is connected to the lower surface central portion of the diaphragm portion, and the lower end thereof is connected to the upper surface central portion of the force receiving body,
The strain detection board further includes a strain detection board disposed at the position of the origin O of the XYZ three-dimensional orthogonal coordinate system and bonded to the diaphragm. The top and bottom faces of the strain detection board are parallel to the XY plane. It is joined to the bottom surface of the groove so that the stress generated by the deformation of the diaphragm portion is transmitted,
The piezoresistive element is formed at a predetermined location on the upper surface of the strain detection substrate,
The detection circuit outputs an electrical signal indicating a moment component Mx and / or My based on a change in electrical resistance of the piezoresistive element. The force sensor according to claim 33,
A force sensor using a capacitance element that detects a displacement of a diaphragm portion as a change in capacitance value as a detection element.

Images