JP7432976B1 - force sensor - Google Patents

Abstract

An object of the present invention is to provide a force sensor that can be miniaturized.
A strain-generating body according to the present invention includes a first connection structure connected to a first sensor body, a second connection structure connected to the first sensor body, a first connection structure and a second connection structure. and a third connection structure that connects the connection structure to the second sensor body. The detection element includes a fixed electrode substrate provided on the second sensor body and a displacement electrode substrate that is displaced together with the second connection structure. When viewed in the first direction, each strain-generating body is arranged at a different position in the circumferential direction with respect to the center of the first sensor body. The strain-generating body is arranged so that the second direction extends outward from the center of the first sensor body.
[Selection diagram] Figure 3

Description

The present invention relates to a force sensor.

2. Description of the Related Art Force sensors are known that output a force acting in a predetermined axial direction and a moment (or torque) acting around a predetermined rotation axis as electrical signals. Force sensors are widely used for force control of various robots, including industrial robots, collaborative robots, life support robots, medical robots, and service robots. With the spread of robots, the market size of force sensors is expanding.

A force sensor is placed between a robot arm and an end effector (or gripper, etc.) and detects a force acting on a workpiece. The detected force is used to control the robot. For example, when a robot arm comes into contact with a person, a force sensor detects the contact. This allows the operation of the robot arm to be stopped in an emergency.

As described above, since the force sensor is disposed between the robot arm and the end effector, it is required to be miniaturized.

JP2021-135103 Publication

The present invention has been made in consideration of these points, and an object of the present invention is to provide a force sensor that can be miniaturized.

[1] This disclosure includes:
a first sensor body subjected to the action of a force or moment to be detected;
a second sensor body disposed at a different position from the first sensor body in the first direction;
a plurality of strain-generating bodies connecting the first sensor body and the second sensor body and elastically deforming due to the action of force or moment received by the first sensor body;
a detection element that detects a change in capacitance value due to a displacement caused by elastic deformation of the strain body;
a detection circuit that outputs an electric signal indicating a force or moment acting on the first sensor body based on a detection result of the detection element;
Equipped with
The strain body includes a first connection structure connected to the first sensor body and a second connection structure connected to the first sensor body, and the strain body is arranged in a second direction perpendicular to the first direction. a second connection structure disposed at a different position from the first connection structure; and a third connection structure that connects the first connection structure and the second connection structure to the second sensor body. and a third connection structure disposed between the first connection structure and the second connection structure in the second direction,
The detection element includes a fixed electrode substrate provided on the second sensor body, and a displacement electrode substrate that is displaced together with the second connection structure and faces the fixed electrode substrate,

When viewed in the first direction, each of the strain-generating bodies is arranged at a different position in a circumferential direction with respect to the center of the first sensor body,
the strain-generating body is arranged such that the second direction is along a direction outward from the center of the first sensor body;
It may also be a force sensor.

[2] This disclosure includes:
The displacement electrode substrate includes, in a third direction orthogonal to each of the first direction and the second direction, a one-side displacement electrode substrate disposed on one side with respect to the central axis of the flexure element; an other side displacement electrode substrate disposed on the other side with respect to the axis;
The force sensor described in [1] may be used.

[3] This disclosure includes:
When viewed in the first direction, the second connection structure of each strain-generating body is located closer to the center of the first sensor body than the corresponding first connection structure. There is,
The force sensor described in [1] or [2] may be used.

[4] This disclosure includes:
When viewed in the first direction, the second direction of each of the strain-generating bodies is arranged radially with respect to the center of the first sensor body.
The force sensor described in any one of [1] to [3] may be used.

[5] This disclosure includes:
The first sensor body and the second sensor body are connected by the four strain bodies,
The force sensor described in any one of [1] to [4] may be used.

[6] This disclosure includes:
The second connection structure includes a 21st connection part extending from the first sensor body toward the second sensor body, and a 22nd connection part that connects the third connection structure and the 21st connection part. , including;
The one-side displacement electrode substrate and the other-side displacement electrode substrate are connected to a surface of the 21st connection portion facing the second sensor body.
The force sensor described in any one of [1] to [5] may be used.

[7] This disclosure includes:
The strain body includes a displacement part connected to a surface of the second connection structure facing the second sensor body,
the one-side displacement electrode substrate and the other-side displacement electrode substrate are connected to a surface of the displacement section facing the second sensor body;
The force sensor described in any one of [1] to [6] may be used.

[8] This disclosure includes:
The first connection structure includes an eleventh connection part extending from the first sensor body toward the second sensor body, and a twelfth connection part connecting the third connection structure and the eleventh connection part. , including;
The second connection structure includes a 21st connection part extending from the first sensor body toward the second sensor body, and a 22nd connection part that connects the third connection structure and the 21st connection part. , including;
The eleventh connection part and the twenty-first connection part extend in the first direction,
the twelfth connecting portion and the twenty-second connecting portion extend in the second direction;
The force sensor described in any one of [1] to [7] may be used.

[9] This disclosure includes:
The distance in the second direction between the one-side displacement electrode substrate and the central axis of the strain-generating body is longer than the distance in the third direction between the one-side displacement electrode substrate and the central axis of the strain-generating body. big,
The force sensor described in any one of [1] to [8] may be used.

[10] The present disclosure includes:
a spring constant of the second connection structure is smaller than a spring constant of the first connection structure;
The force sensor described in any one of [1] to [9] may be used.

[11] This disclosure includes:
The one-side displacement electrode substrate and the other-side displacement electrode substrate protrude from the second connection structure toward the center of the first sensor body when viewed in the first direction.
The force sensor described in any one of [1] to [10] may be used.

[12] This disclosure includes:
The first connection structure includes a first buffer structure that buffers the force acting on the strain body.
The force sensor described in any one of [1] to [11] may be used.

[13] This disclosure includes:
A space is formed between the first connection structure and the second connection structure,
When viewed in the third direction, the first buffer structure is formed such that the space bulges on a side opposite to the second connection structure in the second direction.
The force sensor described in [12] may be used.

[14] This disclosure includes:
When viewed in the third direction, the space portion bulges toward the second sensor body in the first direction and bulges out in the second direction on a side opposite to the second connection structure portion. the first buffer structure is formed so as to
The force sensor described in [13] may be used.

[15] This disclosure includes:
The second connection structure includes a second buffer structure that buffers the force acting on the strain body.
The force sensor described in any one of [1] to [14] may be used.

[16] This disclosure includes:
A space is formed between the first connection structure and the second connection structure,
The second buffer structure is formed such that, when viewed in the third direction, the space bulges out on a side opposite to the first connection structure in the second direction. There is,
The force sensor described in [15] may be used.

[17] This disclosure includes:
A spring constant of the third connection structure is larger than a spring constant of the first connection structure and a spring constant of the second connection structure.
The force sensor described in any one of [1] to [16] may be used.

According to the present invention, it is possible to downsize the force sensor.

FIG. 1 is a perspective view showing an example of a robot to which a force sensor according to the first embodiment is applied. FIG. 2 is a cross-sectional view showing the force sensor according to the first embodiment, and corresponds to a cross-section taken along line AA in FIG. 3, which will be described later. FIG. 3 is a plan view showing the force sensor of FIG. 2 with the force receiving body omitted. FIG. 4 is a front view showing the first strain body of FIG. 2. FIG. FIG. 5 is a side view showing the first strain body of FIG. 4. FIG. FIG. 6 is a plan view showing the first strain body of FIG. 4. FIG. FIG. 7 is a plan view of the strain body of the force sensor shown in FIG. 3. As shown in FIG. FIG. 8 is a front view schematically showing a deformed state of the first strain body in FIG. 4 when the first strain body receives a force on the positive side in the X-axis direction. FIG. 9 is a side view schematically showing a deformed state of the first strain body in FIG. 5 when the first strain body receives a force on the positive side in the Y-axis direction. FIG. 10A is a side view schematically showing a deformed state of the first strain body in FIG. 5 when the first strain body receives a positive force in the Z-axis direction. FIG. 10B is a side view schematically showing a deformed state of the first strain body in FIG. 5 when the first strain body receives a force on the negative side in the Z-axis direction. FIG. 11 is a table showing changes in the capacitance value of each capacitive element in the flexure element shown in FIGS. 4 to 6. FIG. FIG. 12 is a table showing changes in the capacitance value of each capacitive element in the force sensor of FIG. FIG. 13 is a side view showing the first strain body of the force sensor according to the second embodiment. FIG. 14 is a plan view showing the first strain body of FIG. 13. FIG. 15 is a plan view showing a force sensor including the first strain body shown in FIGS. 13 and 14, with the force receiving body omitted. FIG. 16 is a plan view showing a displacement electrode of a force sensor according to the third embodiment. FIG. 17 is a side view showing the first strain body of the force sensor according to the fourth embodiment.

Embodiments of the present invention will be described below with reference to the drawings. In addition, in the drawings attached to this specification, for convenience of illustration and ease of understanding, the scale, vertical and horizontal dimension ratios, etc. are appropriately changed and exaggerated from those of the actual drawings.

As used herein, geometric conditions, physical properties, terms specifying the degree of geometric conditions or physical properties, numerical values indicating geometric conditions or physical properties, etc. are strictly It may be interpreted without being bound by meaning. These geometrical conditions, physical characteristics, terms, numerical values, etc. may be interpreted to include the range to which similar functions can be expected. Examples of terms specifying geometric conditions include "length," "angle," "shape," "parallel," "orthogonal," and "identical."

(First embodiment)
A force sensor according to a first embodiment of the present invention will be described using FIGS. 1 to 12.

First, a robot 1 according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a perspective view showing an example of a robot 1 according to the present embodiment. A force sensor 10 according to this embodiment or the like is attached to the robot 1. Examples of the robot 1 include various robots such as industrial robots, collaborative robots, life support robots, medical robots, and service robots. Below, for convenience, an industrial robot to which the force sensor 10 is attached will be described as an example.

As shown in FIG. 1, the industrial robot 1 includes a robot body 2, a tool 3, a force sensor 10, and a controller 5. The robot body 2 includes a robot arm 4. The robot arm 4 has a multi-joint arm structure.

A force sensor 10 is attached to the tip of the robot arm 4. More specifically, a force sensor 10 is attached between the robot arm 4 and the tool 3. The force sensor 10 is electrically connected to the controller 5 via an electric cable (not shown). Examples of the tool 3 include an end effector (such as a gripper) and a tool changer (both not shown).

The controller 5 controls the force of the robot 1 based on the electrical signal output from the force sensor 10. This controls the operations of the robot body 2 and the tool 3.

The force sensor 10 according to an embodiment of the present invention will be described below with reference to FIGS. 2 to 7. FIG. 2 is a cross-sectional view showing the force sensor according to the present embodiment, and corresponds to the cross-section taken along the line AA in FIG. FIG. 3 is a plan view showing the force sensor of FIG. 2 with the force receiving body omitted. FIG. 4 is a front view showing the first strain body of FIG. 2. FIG. 5 is a side view showing the first flexure body in FIG. 4, and FIG. 6 is a plan view showing the first flexure body in FIG. 4. FIG. 7 is a plan view of each strain-generating body of the force sensor shown in FIG. 3.

In the following explanation, an XYZ three-dimensional coordinate system is defined, the Z-axis direction (first direction) is the vertical direction, and the force is expressed so that the force receiving body 20 is placed on the top side and the fixed body 25 is placed on the bottom side. The description will be made with the sense sensor 10 arranged. For this reason, the force sensor 10 according to the present embodiment is not limited to being used in a posture with the Z-axis direction as the vertical direction. Moreover, it is arbitrary whether either the force receiving body 20 or the fixed body 25 is arranged on the upper side or the lower side.

The force sensor 10 has a function of outputting a force acting in a predetermined axial direction and a moment acting around a predetermined rotation axis as electrical signals. However, the invention is not limited to this, and may be configured to output only one of force and moment as an electrical signal, and furthermore, output at least one axial component of force or moment as an electrical signal. It may be configured as follows.

As shown in FIGS. 2 and 3, the force sensor 10 includes a force receiving body 20, a fixed body 25, strain bodies 30A to 30D, a detection element 70, a detection circuit 75, an exterior body 80, It is equipped with Each component will be explained in more detail below.

The force receiving body 20 is an example of a first sensor body. The force receiving body 20 is subjected to a force or moment to be detected. By receiving this action, the force receiving body 20 moves relative to the fixed body 25. In the example of FIG. 1 described above, the force receiving body 20 is fixed to the tool 3 with bolts or the like, and receives force or moment from the tool 3. The force-receiving body 20 is connected to strain-generating bodies 30A to 30D.

As shown in FIG. 3, in this embodiment, the force receiving body 20 has a circular planar shape. However, the planar shape of the force receiving body 20 is not limited to a circular shape, but may be rectangular, and is arbitrary. The force receiving body 20 may be formed into a flat plate shape.

As shown in FIG. 2, the fixed body 25 is an example of the second sensor body. The fixed body 25 supports the force receiving body 20. The fixed body 25 is arranged at a different position from the force receiving body 20 in the Z-axis direction. More specifically, the fixed body 25 is arranged on the negative side of the force receiving body 20 in the Z-axis direction. The force receiving body 20 and the fixed body 25 are arranged at different positions in the Z-axis direction, and the fixed body 25 is spaced apart from the force receiving body 20. In the example of FIG. 1, the fixed body 25 is fixed to the tip of the robot arm 4 with a bolt or the like, and is supported by the robot body 2. The fixed body 25 is connected to strain-generating bodies 30A to 30D.

As shown in FIG. 3, in this embodiment, the planar shape of the fixed body 25 is circular like the force receiving body 20. The fixed body 25 overlaps the force receiving body 20 when viewed in the Z-axis direction. However, the planar shape of the fixed body 25 is not limited to a circular shape, but may be rectangular, and is arbitrary. The fixed body 25 may be formed into a flat plate shape. Note that at least one of the planar shape of the force receiving body 20 and the planar shape of the fixed body 25 may be circular. In this case, one of the planar shape of the force receiving body 20 and the planar shape of the fixed body 25 may be circular, and the other may be a shape other than circular.

As shown in FIGS. 2 and 3, the strain-generating bodies 30A to 30D connect the force receiving body 20 and the fixed body 25. As shown in FIGS. More specifically, the strain-generating bodies 30A to 30D are arranged between the force-receiving body 20 and the fixed body 25, and the strain-generating bodies 30A-30D are connected to the force-receiving body 20 and connected to the fixed body. 25. The force receiving body 20 is supported by the fixed body 25 via these strain bodies 30A to 30D.

In this embodiment, the force receiving body 20 and the fixed body 25 may be connected by four strain bodies 30A to 30D. The four strain bodies 30A to 30D may include a first strain body 30A, a second strain body 30B, a third strain body 30C, and a fourth strain body 30D.

As shown in FIG. 3, when viewed in the Z-axis direction, the four strain bodies 30A to 30D are arranged at different positions in the circumferential direction with respect to the center O of the force receiving body 20. Each of the strain-generating bodies 30A to 30D is arranged so that a second direction, which will be described later, extends outward from the center O of the force-receiving body 20.

As shown in FIG. 3, when viewed in the Z-axis direction, the second direction (described later) of each strain-generating body 30A to 30D may be arranged radially with respect to the center O of the force receiving body 20. good. Each of the strain-generating bodies 30A to 30D may be arranged such that the second direction is along the radial direction with respect to the center O of the force receiving body 20. The four strain bodies 30A to 30D may be equally arranged in the circumferential direction with respect to the center O of the force receiving body 20 when viewed in the Z-axis direction. For example, when viewed in the Z-axis direction, the center O of the force receiving body 20 may be disposed between the first strain body 30A and the third strain body 30C. Similarly, the center O of the force receiving body 20 may be arranged between the second strain body 30B and the fourth strain body 30D.

More specifically, as shown in FIG. 3, even if the first strain body 30A is arranged on the positive side in the Y-axis direction with respect to the center O of the force-receiving body 20 when viewed in the Z-axis direction, good. In this case, the second direction of the first strain body 30A is along the Y-axis direction, and the first strain body 30A is formed linearly along the Y-axis direction. Similarly, the second strain body 30B may be arranged on the negative side in the X-axis direction with respect to the center O of the force receiving body 20. In this case, the second direction of the second strain body 30B is along the X-axis direction, and the second strain body 30B is formed linearly along the X-axis direction. The third strain body 30C may be arranged on the negative side in the Y-axis direction with respect to the center O of the force receiving body 20. In this case, the second direction of the third strain body 30C is along the Y-axis direction, and the third strain body 30C is formed linearly along the Y-axis direction. The fourth strain body 30D may be arranged on the positive side in the X-axis direction with respect to the center O of the force receiving body 20. In this case, the second direction of the fourth strain body 30D is along the X-axis direction, and the fourth strain body 30D is formed linearly along the X-axis direction.

Note that the second direction of each strain body 30A to 30D is not limited to the example shown in FIG. 3, and may be any direction. Further, the second direction of each strain body 30A to 30D does not need to be along either the X-axis direction or the Y-axis direction as long as it is along the direction outward from the center O of the force-receiving body 20.

The number of strain bodies connecting the force receiving body 20 and the fixed body 25 is not limited to four, and may be two or three, five or more, and is arbitrary. Further, the force receiving body 20 and the fixed body 25 may be connected by only one strain body, and in this case, if the detection element 70 is composed of two capacitive elements as shown in FIG. It is possible to detect two axial components of force. The detection element 70 may be configured with only one capacitive element to detect a uniaxial component of force.

The strain-generating bodies 30A to 30D according to the present embodiment are configured to be elastically deformed by the action of force or moment received by the force-receiving body 20 to cause distortion and to be displaced. Here, of the four strain bodies 30A to 30D described above, the first strain body 30A whose second direction is the Y-axis direction will be explained as an example. The X-axis direction corresponds to the third direction of the first strain body 30A. The third direction is a direction perpendicular to the first direction and perpendicular to the second direction. Since the second strain body 30B, the third strain body 30C, and the fourth strain body 30D have similar configurations, a description of the common configurations will be omitted.

Next, the first strain body 30A will be explained in more detail. As shown in FIGS. 4 to 6, the first strain body 30A includes a first connection structure section 31, a second connection structure section 32, and a third connection structure section 33.

As shown in FIG. 5, the first connection structure section 31 is connected to the force receiving body 20. The first connection structure portion 31 may be formed in an L-shape when viewed in the X-axis direction. The first connection structure section 31 may include an eleventh connection section 34 and a twelfth connection section 35. The first connection structure portion 31 may be elastically deformable when force or moment is applied to the force receiving body 20.

The eleventh connecting portion 34 extends from the force receiving body 20 toward the fixed body 25. The eleventh connecting portion 34 may extend in the Z-axis direction. The eleventh connection portion 34 includes a first connection end portion 36 located on the fixed body 25 side. The first connecting end 36 faces the fixed body 25 .

The twelfth connection part 35 connects the third connection structure part 33 and the eleventh connection part 34. The twelfth connecting portion 35 may extend in the Y-axis direction orthogonal to the Z-axis direction. The twelfth connecting portion 35 extends from the first connecting end 36 in the Y-axis direction.

The second connection structure section 32 is connected to the force receiving body 20. The second connection structure portion 32 may be formed in an L-shape when viewed in the X-axis direction. The second connection structure 32 is arranged at a different position from the first connection structure 31 in the Y-axis direction. The second connection structure 32 may be arranged on the negative side of the first connection structure 31 in the Y-axis direction. The second connection structure 32 may be arranged at the same position as the first connection structure 31 in the X-axis direction. In this case, the first connection structure section 31 and the second connection structure section 32 are arranged along the Y-axis direction. The second connection structure section 32 may include a twenty-first connection section 37 and a twenty-second connection section 38. The second connection structure portion 32 may be elastically deformable when force or moment is applied to the force receiving body 20.

The 21st connecting portion 37 extends from the force receiving body 20 toward the fixed body 25. The 21st connection portion 37 may extend in the Z-axis direction. The twenty-first connection portion 37 includes a second connection end portion 39 located on the fixed body 25 side. The second connection end portion 39 faces the fixed body 25 in the absence of the displacement portion 41, the first capacitive element C1, and the second capacitive element C2.

The 22nd connection part 38 connects the 3rd connection structure part 33 and the 21st connection part 37. The 22nd connecting portion 38 may extend in the Y-axis direction orthogonal to the Z-axis direction. The 22nd connection part 38 extends from the 2nd connection end part 39 in the Y-axis direction. The 22nd connection part 38 may be formed in a straight line with the 12th connection part 35 mentioned above.

The third connection structure 33 connects the first connection structure 31 and the second connection structure 32 to the fixed body 25 . The third connection structure portion 33 may extend in the Z-axis direction. The third connection structure 33 is arranged between the first connection structure 31 and the second connection structure 32 in the Y-axis direction. As shown in FIG. 5, the third connection structure portion 33 may be arranged at a position overlapping the central axis CL of the first strain body 30A. The central axis CL is a line that passes through the center of the first strain body 30A in the X-axis direction and the Y-axis direction and extends in the Z-axis direction. The third connection structure section 33 may be arranged at the same position as the first connection structure section 31 and the second connection structure section 32 in the X-axis direction. In this case, the first connection structure section 31, the second connection structure section 32, and the third connection structure section 33 are arranged along the Y-axis direction. The third connection structure portion 33 may be elastically deformable when force or moment is applied to the force receiving body 20.

The third connection structure portion 33 includes a third connection end portion 40 located on the force receiving body 20 side. The third connection end 40 faces the force receiving body 20. The above-described twelfth connection portion 35 and twenty-second connection portion 38 may each extend from the third connection end portion 40 in the Y-axis direction. Regarding the first strain body 30A, a twelfth connecting portion 35 extends from the third connecting end 40 toward the positive side in the Y-axis direction, and a twenty-second connecting portion 38 extends toward the negative side in the Y-axis direction.

The first strain body 30A may further include a displacement portion 41. As shown in FIG. 5, the displacement portion 41 may be arranged on one side with respect to the central axis CL of the first strain body 30A when viewed in the X-axis direction. The displacement portion 41 may be arranged on the negative side in the Y-axis direction with respect to the central axis CL of the first strain body 30A.

The displacement part 41 may be connected to the second connection structure part 32. The displacement portion 41 may be connected to a surface of the second connection structure portion 32 that faces the fixed body 25 . The displacement part 41 may be connected to the 21st connection part 37 of the second connection structure part 32. More specifically, the displacement portion 41 may be connected to the second connection end portion 39 of the twenty-first connection portion 37 . The displacement portion 41 may be connected to the surface of the second connection end 39 facing the fixed body 25 (corresponding to the lower surface of the second connection end 39 in FIG. 5). The displacement portion 41 may have a thickness in the Z-axis direction. Thereby, the surface of the displacement part 41 facing the fixed body 25 can be brought closer to the fixed body 25 than the surface of the second connection end 39 facing the fixed body 25. However, the displacement part 41 may be connected to the surface of the second connecting part 38 that faces the fixed body 25.

Among the strain-generating bodies 30A configured as described above, the first strain-generating body 30A may be integrally formed of a continuous material. The first strain body 30A may be produced by machining (for example, cutting) from one block material, or may be produced by casting. The first strain body 30A may be made of a metal material such as an aluminum alloy or an iron alloy. The above-mentioned displacement part 41 may be attached to the second connection structure part 32 as a separate part, or may be formed integrally with the second connection structure part 32 from a continuous material.

As shown in FIG. 3, the first strain body 30A according to the present embodiment is arranged on the positive side in the Y-axis direction with respect to the center O of the force-receiving body 20 when viewed in the Z-axis direction. The second direction of the first strain body 30A is along the Y-axis direction. The second connection structure portion 32 of the first strain body 30A is located closer to the center O of the force receiving body 20 than the first connection structure portion 31 of the first strain body 30A. In other words, the second connection structure portion 32 is disposed on the inner side of the force receiving body 20 in the radial direction than the first connection structure portion 31 and on the negative side of the first connection structure portion 31 in the Y-axis direction. As a result, the displacement portion 41 of the first strain body 30A is arranged inside the force receiving body 20 in the radial direction.

The second strain body 30B according to the present embodiment is arranged on the negative side in the X-axis direction with respect to the center O of the force-receiving body 20 when viewed in the Z-axis direction. The second direction of the second strain body 30B is along the X-axis direction. The second connection structure portion 32 of the second strain body 30B is located closer to the center O of the force receiving body 20 than the first connection structure portion 31 of the second strain body 30B. In other words, the second connection structure section 32 is disposed on the radially inner side of the force receiving body 20 than the first connection structure section 31 and on the positive side of the X-axis direction than the first connection structure section 31 . As a result, the displacement portion 41 of the second strain body 30B is arranged inside the force receiving body 20 in the radial direction.

The third strain body 30C according to the present embodiment is arranged on the negative side in the Y-axis direction with respect to the center O of the force-receiving body 20 when viewed in the Z-axis direction. The second direction of the third strain body 30C is along the Y-axis direction. The second connection structure portion 32 of the third strain body 30C is located closer to the center O of the force receiving body 20 than the first connection structure portion 31 of the third strain body 30C. In other words, the second connection structure section 32 is disposed on the radially inner side of the force receiving body 20 than the first connection structure section 31 and on the positive side in the Y-axis direction than the first connection structure section 31 . As a result, the displacement portion 41 of the third strain body 30C is arranged inside the force receiving body 20 in the radial direction.

The fourth strain body 30D according to the present embodiment is arranged on the positive side in the X-axis direction with respect to the center O of the force-receiving body 20 when viewed in the Z-axis direction. The second direction of the fourth strain body 30D is along the X-axis direction. The second connection structure portion 32 of the fourth strain body 30D is located closer to the center O of the force receiving body 20 than the first connection structure portion 31 of the fourth strain body 30D. In other words, the second connection structure section 32 is disposed on the inner side of the force receiving body 20 in the radial direction than the first connection structure section 31 and on the negative side of the first connection structure section 31 in the X-axis direction. As a result, the displacement portion 41 of the fourth strain body 30D is arranged inside the force receiving body 20 in the radial direction.

Next, the detection element 70 according to this embodiment will be explained.

The detection element 70 is configured to detect displacement caused by elastic deformation of each of the above-mentioned strain bodies 30A to 30D. The detection element 70 according to the present embodiment may include a fixed electrode substrate provided on the fixed body 25 and a displacement electrode substrate that is displaced together with the second connection structure portion 32 of each of the strain bodies 30A to 30D. good. The detection element 70 according to the present embodiment may include a first capacitive element C1 to an eighth capacitive element C8. Each capacitive element C1 to C8 may be composed of a fixed electrode substrate and a displacement electrode substrate.

As shown in FIGS. 4 to 6, the first capacitive element C1 and the second capacitive element C2 each detect a change in capacitance value based on the displacement of the second connection structure portion 32 of the first strain body 30A. The first capacitive element C1 and the second capacitive element C2 are capacitive elements for the first strain body 30A shown in FIGS. 4 to 6.

The displacement electrode substrate that is displaced together with the second connection structure portion 32 of the first strain body 30A may include a first displacement electrode substrate Ed1 and a second displacement electrode substrate Ed2. One example of the one side displacement electrode substrate and the other side displacement electrode substrate is the first displacement electrode substrate Ed1, and the other example is the second displacement electrode substrate Ed2. The fixed electrode substrate for the first strain body 30A may include a first fixed electrode substrate Ef1 and a second fixed electrode substrate Ef2.

In the examples shown in FIGS. 4 to 6, the first capacitive element C1 includes a first fixed electrode substrate Ef1 and a first displacement electrode substrate Ed1. The second capacitive element C2 includes a second fixed electrode substrate Ef2 and a second displacement electrode substrate Ed2. In this embodiment, the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 are provided in the displacement portion 41 of the first strain body 30A. The first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 are provided on the fixed body 25.

As shown in FIGS. 4 and 6, the first fixed electrode substrate Ef1 is arranged on the positive side in the X-axis direction with respect to the central axis CL of the first strain body 30A. The second fixed electrode substrate Ef2 is arranged on the negative side in the X-axis direction with respect to the central axis CL of the first flexure element 30A.

As shown in FIG. 4, the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 may be integrated. More specifically, the fixed electrode of the first fixed electrode substrate Ef1 and the fixed electrode of the second fixed electrode substrate Ef2 are integrated to form the common fixed electrode Efc. The insulator of the first fixed electrode substrate Ef1 and the insulator of the second fixed electrode substrate Ef2 are integrated to form a common insulator IBfc. The common insulator IBfc may be joined to the fixed body 25 with an adhesive or the like, or may be fixed with a bolt or the like. The entire common insulator IBfc may be joined to the fixed body 25. However, the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 may be formed separately. In this case, the fixed electrodes of the first fixed electrode substrate Ef1 and the fixed electrodes of the second fixed electrode substrate Ef2 may be formed separately and spaced apart from each other. The insulator of the first fixed electrode substrate Ef1 and the insulator of the second fixed electrode substrate Ef2 may be formed separately, or may be integrated to form a common insulator IBfc.

As shown in FIGS. 4 and 6, the first displacement electrode substrate Ed1 is arranged on the positive side in the X-axis direction with respect to the central axis CL of the first strain body 30A. The first displacement electrode substrate Ed1 faces the above-described first fixed electrode substrate Ef1. The second displacement electrode substrate Ed2 is arranged on the negative side in the X-axis direction with respect to the central axis CL of the first strain body 30A. The second displacement electrode substrate Ed2 faces the above-mentioned second fixed electrode substrate Ef2. The first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 may be connected to the above-described displacement section 41 of the second connection structure section 32, and the surface of the displacement section 41 facing the fixed body 25 (in FIG. (corresponding to the lower surface of the displacement part 41).

As shown in FIG. 4, the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 each include a displacement electrode Ed and an insulator. The displacement electrodes Ed of the first displacement electrode substrate Ed1 are opposed to the fixed electrodes of the first fixed electrode substrate Ef1, and the displacement electrodes of the second displacement electrode substrate Ed2 are opposed to the fixed electrodes of the second fixed electrode substrate Ef2. . The displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 may be formed separately and spaced apart from each other. The insulator is interposed between the displacement electrode Ed and the displacement section 41. The insulator of the first displacement electrode substrate Ed1 and the insulator of the second displacement electrode substrate Ed2 may be integrated to form a common insulator IBdc. The common insulator IBdc may be joined to the displacement portion 41 with an adhesive or the like, or may be fixed with a bolt or the like. A part of the common insulator IBdc may be joined to the displacement part 41. A support plate (not shown) may be interposed between the common insulator IBdc and the displacement portion 41. As will be described later, when the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 are formed of FPC boards, the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 are supported by a support plate. Good too.

As shown in FIGS. 3 to 7, the first capacitive element C1 and the second capacitive element C2 are arranged at the same position in the Y-axis direction. That is, the displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 are arranged at the same position in the Y-axis direction. The first capacitive element C1 and the second capacitive element C2 are arranged on the negative side in the Y-axis direction with respect to the third connection structure section 33 of the first strain body 30A.

As shown in FIG. 6, the distance L2 in the Y-axis direction may be larger than the distance L1 in the X-axis direction. The distance L1 in the X-axis direction is the distance in the X-axis direction between the center of the first displacement electrode substrate Ed1 and the central axis CL of the first strain body 30A. The distance in the X-axis direction between the center of the first displacement electrode substrate Ed1 and the central axis CL may be equal to the distance in the X-axis direction between the center of the second displacement electrode substrate Ed2 and the central axis CL. The distance L2 in the Y-axis direction is the distance in the Y-axis direction between the center of the first displacement electrode substrate Ed1 and the central axis CL of the first strain body 30A. The distance in the Y-axis direction between the center of the first displacement electrode substrate Ed1 and the central axis CL may be equal to the distance in the Y-axis direction between the center of the second displacement electrode substrate Ed2 and the central axis CL. In FIG. 6, the central axis CL is shown as a point.

In this embodiment, the planar shape of the common fixed electrode Efc that integrates the fixed electrodes of the fixed electrode substrates Ef1 and Ef2 is rectangular. The planar shape of the displacement electrodes Ed of the displacement electrode substrates Ed1 and Ed2 is also rectangular. However, the planar shapes of the common fixed electrode Efc and the displacement electrode Ed are not limited to rectangular shapes, and may be other shapes such as circular, polygonal, and elliptical shapes.

When viewed in the Z-axis direction, the planar shape of the displacement electrode Ed of the first displacement electrode substrate Ed1 may be smaller than the planar shape of the common fixed electrode Efc. Even if the force receiving body 20 receives a force or moment and the first displacement electrode substrate Ed1 is displaced, the displacement electrodes Ed of the first displacement electrode substrate Ed1 are common as a whole when viewed in the Z-axis direction. The size of the displacement electrode Ed and the size of the common fixed electrode Efc may be set so as to overlap the fixed electrode Efc. Thereby, it is possible to prevent the opposing area between the displacement electrode Ed and the common fixed electrode Efc from changing, and it is possible to prevent the change in the opposing area from affecting a change in the capacitance value. Therefore, the capacitance value can be changed according to a change in the distance between the displacement electrode Ed and the common fixed electrode Efc. Here, the opposing area refers to the area where the displacement electrode Ed and the common fixed electrode Efc overlap when viewed in the Z-axis direction. When the second connection structure portion 32 is tilted, the displacement electrode Ed, which is smaller than the common fixed electrode Efc, may be tilted and the opposing area may vary, but the tilt angle of the displacement electrode Ed in this case is small. As a result, the change in capacitance value is dominated by the distance between the displacement electrode Ed and the common fixed electrode Efc. Therefore, in this specification, changes in the facing area due to the inclination of the displacement electrode Ed are not considered, and changes in the capacitance value are considered to be caused by changes in the distance between the displacement electrode Ed and the common fixed electrode Efc. Note that in FIG. 8 and the like described later, the inclinations of the displacement electrode substrates Ed1 to Ed8 are exaggerated to make the drawings clearer.

Similarly, when viewed in the Z-axis direction, the planar shape of the displacement electrode Ed of the second displacement electrode substrate Ed2 may be smaller than the common fixed electrode Efc. The planar shape of the displacement electrode Ed of the second displacement electrode substrate Ed2 may be the same as the planar shape of the displacement electrode Ed of the first displacement electrode substrate Ed1.

The planar shape of the common fixed electrode Efc of the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 is the same size as the planar shape of the common insulator IBfc of the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2. There may be. However, the planar shape of the common fixed electrode Efc may be smaller than the planar shape of the common insulator IBfc. The planar shape of the displacement electrode Ed of the first displacement electrode substrate Ed1 and the planar shape of the displacement electrode Ed of the second displacement electrode substrate Ed2 are the plane of the common insulator IBdc of the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2, respectively. It may be smaller than the shape.

The insulator may be made of an insulating material such as polyimide film, glass epoxy resin, or ceramic. A metal thin film constituting the above-mentioned fixed electrode or displacement electrode is formed on the insulator.

The fixed electrode substrates Ef1 and Ef2 may be composed of FPC boards (flexible printed circuit boards). The FPC board is a flexible printed circuit board that is formed into a thin film shape. In the FPC board, a metal thin film forming electrodes and wiring is formed on a polyimide film. Portions of the FPC board corresponding to the fixed electrode boards Ef1 and Ef2 may be fixed to the fixed body 25. The FPC board may include wiring that connects the common fixed electrode Efc to the detection circuit 75. The displacement electrode substrates Ed1 and Ed2 may be similarly constructed of FPC substrates. In this case, portions corresponding to the displacement electrode substrates Ed1 and Ed2 may be fixed to the displacement portion 41. The FPC board may include wiring that connects the displacement electrode Ed to the detection circuit 75.

The configuration of the first strain body 30A and the corresponding detection element 70 described above can be similarly applied to the second strain body 30B, the third strain body 30C, and the fourth strain body 30D.

That is, as shown in FIG. 3, the third capacitive element C3 and the fourth capacitive element C4 each detect a change in capacitance value based on the displacement of the second connection structure portion 32 of the second strain body 30B. The third capacitive element C3 and the fourth capacitive element C4 are capacitive elements for the second strain body 30B.

The displacement electrode substrate that is displaced together with the second connection structure portion 32 of the second strain body 30B may include a third displacement electrode substrate Ed3 and a fourth displacement electrode substrate Ed4. One example of the one side displacement electrode substrate and the other side displacement electrode substrate is the third displacement electrode substrate Ed3, and the other example is the fourth displacement electrode substrate Ed4. The fixed electrode substrate for the second strain body 30B may include a third fixed electrode substrate Ef3 and a fourth fixed electrode substrate Ef4.

As shown in FIG. 7, the third capacitive element C3 includes a third fixed electrode substrate Ef3 and a third displacement electrode substrate Ed3. The fourth capacitive element C4 includes a fourth fixed electrode substrate Ef4 and a fourth displacement electrode substrate Ed4. In this embodiment, the third displacement electrode substrate Ed3 and the fourth displacement electrode substrate Ed4 are provided in the displacement portion 41 of the second strain body 30B. The third fixed electrode substrate Ef3 and the fourth fixed electrode substrate Ef4 are provided on the fixed body 25.

The third fixed electrode substrate Ef3 is arranged on the positive side in the Y-axis direction with respect to the central axis CL of the second strain body 30B. The fourth fixed electrode substrate Ef4 is arranged on the negative side in the Y-axis direction with respect to the central axis CL of the second strain body 30B. In the present embodiment, the third fixed electrode substrate Ef3 and the fourth fixed electrode substrate Ef4 are integrated and configured in the same manner as the fixed electrode substrates Ef1 and Ef2 described above.

The third displacement electrode substrate Ed3 is arranged on the positive side in the Y-axis direction with respect to the central axis CL of the second strain body 30B. The third displacement electrode substrate Ed3 faces the above-mentioned third fixed electrode substrate Ef3. The fourth displacement electrode substrate Ed4 is arranged on the negative side in the Y-axis direction with respect to the central axis CL of the second strain body 30B. The fourth displacement electrode substrate Ed4 faces the above-mentioned fourth fixed electrode substrate Ef4. The displacement electrode substrates Ed3 and Ed4 are configured similarly to the displacement electrode substrates Ed1 and Ed2 described above.

As shown in FIGS. 3 and 7, the third capacitive element C3 and the fourth capacitive element C4 are arranged at the same position in the X-axis direction. That is, the displacement electrode Ed of the third displacement electrode substrate Ed3 and the displacement electrode Ed of the fourth displacement electrode substrate Ed4 are arranged at the same position in the X-axis direction. The third capacitive element C3 and the fourth capacitive element C4 are arranged on the positive side in the X-axis direction with respect to the third connection structure portion 33 of the second strain body 30B.

Further, as shown in FIG. 3, the fifth capacitive element C5 and the sixth capacitive element C6 each detect a change in capacitance value based on the displacement of the second connection structure portion 32 of the third strain body 30C. The fifth capacitive element C5 and the sixth capacitive element C6 are capacitive elements for the third strain body 30C.

The displacement electrode substrate that is displaced together with the second connection structure portion 32 of the third strain body 30C may include a fifth displacement electrode substrate Ed5 and a sixth displacement electrode substrate Ed6. One example of the one side displacement electrode substrate and the other side displacement electrode substrate is the fifth displacement electrode substrate Ed5, and the other example is the sixth displacement electrode substrate Ed6. The fixed electrode substrate for the third strain body 30C may include a fifth fixed electrode substrate Ef5 and a sixth fixed electrode substrate Ef6.

As shown in FIG. 7, the fifth capacitive element C5 includes a fifth fixed electrode substrate Ef5 and a fifth displacement electrode substrate Ed5. The sixth capacitive element C6 includes a sixth fixed electrode substrate Ef6 and a sixth displacement electrode substrate Ed6. In this embodiment, the fifth displacement electrode substrate Ed5 and the sixth displacement electrode substrate Ed6 are provided in the displacement portion 41 of the third strain body 30C. The fifth fixed electrode substrate Ef5 and the sixth fixed electrode substrate Ef6 are provided on the fixed body 25.

The fifth fixed electrode substrate Ef5 is arranged on the negative side in the X-axis direction with respect to the central axis CL of the third strain body 30C. The sixth fixed electrode substrate Ef6 is arranged on the positive side in the X-axis direction with respect to the central axis CL of the third strain body 30C. In the present embodiment, the fifth fixed electrode substrate Ef5 and the sixth fixed electrode substrate Ef6 are integrated and configured similarly to the fixed electrode substrates Ef1 and Ef2 described above.

The fifth displacement electrode substrate Ed5 is arranged on the negative side in the X-axis direction with respect to the central axis CL of the third strain body 30C. The fifth displacement electrode substrate Ed5 faces the above-mentioned fifth fixed electrode substrate Ef5. The sixth displacement electrode substrate Ed6 is arranged on the positive side in the X-axis direction with respect to the central axis CL of the third strain body 30C. The sixth displacement electrode substrate Ed6 faces the above-mentioned sixth fixed electrode substrate Ef6. The displacement electrode substrates Ed5 and Ed6 are configured similarly to the displacement electrode substrates Ed1 and Ed2 described above.

As shown in FIGS. 3 and 7, the fifth capacitive element C5 and the sixth capacitive element C6 are arranged at the same position in the Y-axis direction. That is, the displacement electrode Ed of the fifth displacement electrode substrate Ed5 and the displacement electrode Ed of the sixth displacement electrode substrate Ed6 are arranged at the same position in the Y-axis direction. The fifth capacitive element C5 and the sixth capacitive element C6 are arranged on the positive side in the Y-axis direction with respect to the third connection structure portion 33 of the third strain body 30C.

Further, as shown in FIG. 3, the seventh capacitive element C7 and the eighth capacitive element C8 each detect a change in capacitance value based on the displacement of the second connection structure portion 32 of the fourth strain body 30D. The seventh capacitive element C7 and the eighth capacitive element C8 are capacitive elements for the fourth strain body 30D.

The displacement electrode substrate that is displaced together with the second connection structure portion 32 of the fourth strain body 30D may include a seventh displacement electrode substrate Ed7 and an eighth displacement electrode substrate Ed8. One example of the one side displacement electrode substrate and the other side displacement electrode substrate is the seventh displacement electrode substrate Ed7, and the other example is the eighth displacement electrode substrate Ed8. The fixed electrode substrate for the fourth strain body 30D may include a seventh fixed electrode substrate Ef7 and an eighth fixed electrode substrate Ef8.

As shown in FIG. 7, the seventh capacitive element C7 includes a seventh fixed electrode substrate Ef7 and a seventh displacement electrode substrate Ed7. The eighth capacitive element C8 includes an eighth fixed electrode substrate Ef8 and an eighth displacement electrode substrate Ed8. In this embodiment, the seventh displacement electrode substrate Ed7 and the eighth displacement electrode substrate Ed8 are provided in the displacement portion 41 of the fourth strain body 30D. The seventh fixed electrode substrate Ef7 and the eighth fixed electrode substrate Ef8 are provided on the fixed body 25.

The seventh fixed electrode substrate Ef7 is arranged on the negative side in the Y-axis direction with respect to the central axis CL of the fourth strain body 30D. The eighth fixed electrode substrate Ef8 is arranged on the positive side in the Y-axis direction with respect to the central axis CL of the fourth strain body 30D. In the present embodiment, the seventh fixed electrode substrate Ef7 and the eighth fixed electrode substrate Ef8 are integrated and configured in the same manner as the fixed electrode substrates Ef1 and Ef2 described above.

The seventh displacement electrode substrate Ed7 is arranged on the negative side in the Y-axis direction with respect to the central axis CL of the fourth strain body 30D. The seventh displacement electrode substrate Ed7 faces the aforementioned seventh fixed electrode substrate Ef7. The eighth displacement electrode substrate Ed8 is arranged on the positive side in the Y-axis direction with respect to the central axis CL of the fourth strain body 30D. The eighth displacement electrode substrate Ed8 faces the above-mentioned eighth fixed electrode substrate Ef8. The displacement electrode substrates Ed7 and Ed8 are configured similarly to the displacement electrode substrates Ed1 and Ed2 described above.

As shown in FIGS. 3 and 7, the seventh capacitive element C7 and the eighth capacitive element C8 are arranged at the same position in the X-axis direction. That is, the displacement electrode Ed of the seventh displacement electrode substrate Ed7 and the displacement electrode Ed of the eighth displacement electrode substrate Ed8 are arranged at the same position in the X-axis direction. The seventh capacitive element C7 and the eighth capacitive element C8 are arranged on the negative side in the X-axis direction with respect to the third connection structure portion 33 of the fourth strain body 30D.

As shown in FIG. 2, the detection circuit 75 outputs an electric signal indicating the force or moment acting on the strain bodies 30A to 30D based on the detection result of the detection element 70. This detection circuit 75 may have an arithmetic function configured by a microprocessor, for example. Further, the detection circuit 75 may have an A/D conversion function for converting the analog signal received from the detection element 70 described above into a digital signal, and a function for amplifying the signal. The detection circuit 75 may include a terminal that outputs an electrical signal, and the electrical signal is transmitted from this terminal to the above-mentioned controller 5 via an electrical cable (not shown).

As shown in FIGS. 2 and 3, the exterior body 80 is configured to cover the four strain-generating bodies 30A to 30D from the outside when viewed in the Z-axis direction. The exterior body 80 may be a cylindrical housing that constitutes the force sensor 10. The strain-generating bodies 30A to 30D are housed in an exterior body 80. In this embodiment, the planar cross-sectional shape (the shape in the cross section along the XY plane) of the exterior body 80 may be a circular frame shape. A buffer member 81 may be interposed in the gap between the force receiving body 20 and the exterior body 80. The buffer member 81 may be made of an elastically deformable flexible material such as rubber or sponge.

Next, a method of detecting force or moment by applying force or moment to force sensor 10 according to the present embodiment having such a configuration will be described with reference to FIGS. 8 to 10B. 8 is a front view schematically showing a deformed state of the first strain body 30A when the first strain body 30A in FIG. 4 receives a force Fx on the positive side in the X-axis direction, and FIG. 5 is a side view schematically showing a deformed state of the first strain body 30A when the first strain body 5 receives a force Fy on the positive side in the Y-axis direction. FIG. FIG. 10A is a side view schematically showing a deformed state of the first strain body 30A in FIG. 5 when the first strain body 30A in FIG. 5 receives a force Fz on the positive side in the Z-axis direction. FIG. 10B is a side view schematically showing a deformed state of the first strain body 30A in FIG. 5 when the first strain body 30A receives a force on the negative side in the Z-axis direction.

When the force receiving body 20 is subjected to a force or moment, the force or moment is transmitted to the first strain body 30A to the fourth strain body 30D. More specifically, the force or moment is transmitted to the first connecting structure 31, the second connecting structure 32, and the third connecting structure 33, causing elastic deformation. This causes the displacement portion 41 to be displaced. Therefore, the distance between each fixed electrode substrate Ef1 to Ef8 of the detection element 70 and the corresponding displacement electrode substrate Ed1 to Ed8 changes, and the capacitance value of each capacitive element C1 to C8 changes. This change in capacitance value is detected by the detection element 70 as a displacement occurring in the strain-generating bodies 30A to 30D. In this case, the capacitance values of each of the capacitive elements C1 to C8 may change differently. Therefore, the detection circuit 75 detects the direction and magnitude of the force or moment acting on the force receiving body 20 based on the change in the capacitance value of each capacitive element C1 to C8 detected by the detection element 70. be able to.

Here, first, taking the first strain body 30A as an example, the first capacitive element C1 and the second capacitive element when a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a force Fz in the Z-axis direction are applied. A change in the capacitance value of C2 will be explained.

(When +Fx works)
When force Fx acts on the first strain body 30A in the positive direction of the X-axis, as shown in FIG. While the third connection structure portion 33 is elastically deformed, each of the connection structure portions 31 to 33 tilts toward the positive side in the X-axis direction. In other words, the first connection structure part 31, the second connection structure part 32, and the third connection structure part 33 are the same when viewed toward the positive side in the Y-axis direction (when viewed toward the paper surface of FIG. 8). , rotate clockwise. Roughly speaking, each of the connection structures 31 to 33 rotates around the connection point between the third connection structure 33 and the fixed body 25. In conjunction with the second connection structure 32, the displacement part 41 rotates clockwise and tilts.

The first displacement electrode substrate Ed1 approaches the first fixed electrode substrate Ef1, and the inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 decreases. Therefore, the capacitance value of the first capacitive element C1 increases. On the other hand, the second displacement electrode substrate Ed2 moves away from the second fixed electrode substrate Ef2, and the inter-electrode distance (distance in the Z-axis direction) between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 increases. Therefore, the capacitance value of the second capacitive element C2 decreases.

(When -Fx works)
When the force Fx acts on the first strain body 30A in the negative side of the X-axis direction, although not shown, a phenomenon opposite to that shown in FIG. 8 occurs. That is, the capacitance value of the first capacitive element C1 decreases, and the capacitance value of the second capacitive element C2 increases.

(When +Fy acts)
When a force Fy is applied to the first strain body 30A in the positive direction of the Y-axis, the first connecting structure 31, the second connecting structure 32, and the third connecting structure 33 are moved as shown in FIG. While being elastically deformed, it tilts toward the positive side in the Y-axis direction. In other words, the first connection structure section 31, the second connection structure section 32, and the third connection structure section 33 are the same when viewed toward the positive side in the X-axis direction (when viewed toward the paper surface of FIG. 9). , rotate counterclockwise. In conjunction with the second connection structure 32, the displacement part 41 rotates counterclockwise and tilts. Roughly speaking, each of the connection structures 31 to 33 rotates around the connection point between the third connection structure 33 and the fixed body 25. In this case, the displacement portion 41 is displaced in a direction away from the fixed body 25.

The first displacement electrode substrate Ed1 moves away from the first fixed electrode substrate Ef1, and the inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 increases. Therefore, the capacitance value of the first capacitive element C1 decreases. Similarly, the second displacement electrode substrate Ed2 moves away from the second fixed electrode substrate Ef2, and the inter-electrode distance (distance in the Z-axis direction) between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 increases. Therefore, the capacitance value of the second capacitive element C2 decreases.

(When -Fy acts)
When force Fy is applied to the first strain body 30A in the Y-axis direction negative side, although not shown, a phenomenon opposite to that shown in FIG. 9 occurs. That is, the capacitance value of the first capacitive element C1 increases, and the capacitance value of the second capacitive element C2 increases.

(When +Fz acts)
When force Fz is applied to the first strain body 30A in the positive Z-axis direction, the first connection structure portion 31 and the second connection structure portion 32 are elastically deformed, as shown in FIG. 10A. In this case, the 21st connection part 37 of the second connection structure part 32 is displaced to the positive side in the Z-axis direction, and the 22nd connection part 38 is inclined. In conjunction with the second connection structure section 32, the displacement section 41 is displaced toward the positive side in the Z-axis direction. In this case, the displacement portion 41 is displaced in a direction away from the fixed body 25.

The first displacement electrode substrate Ed1 moves away from the first fixed electrode substrate Ef1, and the inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 increases. Therefore, the capacitance value of the first capacitive element C1 decreases. Similarly, the second displacement electrode substrate Ed2 moves away from the second fixed electrode substrate Ef2, and the inter-electrode distance (distance in the Z-axis direction) between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 increases. Therefore, the capacitance value of the second capacitive element C2 decreases.

(When -Fz acts)
When force Fz is applied to the first strain body 30A in the negative direction in the Z-axis direction, as shown in FIG. 10B, a phenomenon opposite to that shown in FIG. 10A occurs.

When force Fz is applied to the first strain body 30A in the negative Z-axis direction, the first connection structure portion 31 and the second connection structure portion 32 are elastically deformed, as shown in FIG. 10B. In this case, the 21st connection portion 37 of the second connection structure portion 32 is displaced to the negative side in the Z-axis direction, and the 22nd connection portion 38 is inclined. In conjunction with the second connection structure section 32, the displacement section 41 is displaced toward the negative side in the Z-axis direction. In this case, the displacement portion 41 is displaced in a direction approaching the fixed body 25.

The first displacement electrode substrate Ed1 approaches the first fixed electrode substrate Ef1, and the inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 decreases. Therefore, the capacitance value of the first capacitive element C1 increases. Similarly, the second displacement electrode substrate Ed2 approaches the second fixed electrode substrate Ef2, and the inter-electrode distance (distance in the Z-axis direction) between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 decreases. Therefore, the capacitance value of the second capacitive element C2 increases.

Here, FIG. 11 shows changes in the capacitance values of the respective capacitive elements C1 and C2 provided in the first strain body 30A shown in FIG. 4. FIG. 11 is a table showing changes in the capacitance values of the capacitive elements C1 and C2 in the first strain body 30A of FIGS. 4 to 6.

FIG. 11 shows changes in the capacitance values of the capacitive elements C1 and C2 with respect to the force Fx in the X-axis direction, the force Fy in the Y-axis direction, and the force Fz in the Z-axis direction. A case where the capacitance value decreases is shown as "- (minus)", and a case where the capacitance value increases is shown as "+ (plus)". For example, "+" is shown in C1 in the Fx row in the table shown in FIG. It shows that the value increases. On the other hand, "-" is shown in C2 in the Fx row in the table shown in FIG. It shows that the value decreases. For the sake of simplicity, in FIG. 11, changes in capacitance values are simply represented by symbols.

From the table shown in FIG. 11, in the force sensor 10 in which the force receiving body 20 and the fixed body 25 are connected only by the first strain body 30A, the forces Fx, Fy, and Fz acting on the force receiving body 20 are as follows. It can be calculated using the following formula. In addition, in the following formula, for convenience, force or moment and the amount of change in capacitance value are connected with "=". However, since the force or moment and the capacitance value are mutually different physical quantities, the force is actually calculated by converting the amount of change in the capacitance value. C1 and C2 in the following formula indicate the amount of change in capacitance value in each capacitive element.

As shown in FIG. 11, in the force sensor 10 in which the force receiving body 20 and the fixed body 25 are connected only by the first strain body 30A, the force Fx in the X-axis direction is It can be detected by the difference between the capacitance value and the capacitance value of the second capacitive element C2. That is, as shown in the above equation (1), the force Fx is determined by the difference between the amount of change in the capacitance value of the first capacitive element C1 and the amount of change in the capacitance value of the second capacitive element C2. Output values can be calculated. Even if the capacitance value of the first capacitive element C1 and the capacitance value of the second capacitive element C2 include the influence of disturbances such as noise or ambient temperature, the influence is calculated by the above equation ( It can be canceled out by the difference in 1). Therefore, the output value of the force Fx can be prevented from being influenced by disturbances, and the performance of the force sensor 10 can be improved.

Note that, as shown in the above equations (2) and (3), the amount of change in capacitance decreases for both Fy and Fz, and the formulas are the same. This makes it difficult to determine whether the detected force is Fy or Fz. Therefore, the force sensor 10 using only one first strain body 30A can be used when either one of the force Fy and the force Fz and the force Fx act. The force sensor 10 in this case is a force sensor capable of detecting two-axis components.

Next, in the force sensor 10 shown in FIG. 7, force Fx in the X-axis direction, force Fy in the Y-axis direction, force Fz in the Z-axis direction, moment Mx around the X-axis, moment My around the Y-axis, and moment My around the Z-axis. A change in the capacitance value of each capacitive element C1 to C8 when a surrounding moment Mz acts will be explained with reference to FIG. 12. FIG. 12 is a table showing changes in the capacitance value of each capacitive element in the force sensor of FIG.

(When +Fx works)
First, a case will be described in which a force Fx is applied to the force receiving body 20 shown in FIG. 7 on the positive side in the X-axis direction.

In this case, the first flexural body 30A is elastically deformed in the same way as the first flexural body 30A shown in FIG. Capacitance value decreases. In this case, since the distance in the X-axis direction (corresponding to L1 in FIG. 6) between the center of the first displacement electrode substrate Ed1 and the central axis CL is relatively small, the amount of increase in the capacitance value of the first capacitive element C1 is Becomes relatively small. Similarly, the amount of decrease in the capacitance value of the second capacitive element C2 becomes relatively small.

The second strain body 30B is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases. More specifically, the second connection structure portion 32 of the second strain body 30B rotates clockwise and tilts when viewed toward the positive side in the Y-axis direction. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the second strain body 30B and the fixed body 25. Since the distance in the X-axis direction (corresponding to L2 in FIG. 6) between the center of the third displacement electrode substrate Ed3 and the central axis CL is relatively large, the third displacement electrode substrate Ed3 moves in a direction closer to the third fixed electrode substrate Ef3. The amount of displacement is relatively large. Therefore, when the force Fx acts on the force receiving body 20 in the positive direction of the X-axis, the amount of increase in the capacitance value of the third capacitive element C3 becomes relatively large. Therefore, C3 in the Fx row in the table shown in FIG. 12 is set to "++". Since the amount of increase in the capacitance value of the fourth capacitive element C4 is also relatively large, C4 in the Fx row in the table shown in FIG. 12 is set to "++".

The third strain body 30C is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases. In this case, since the distance in the X-axis direction (corresponding to L1 in FIG. 6) between the center of the fifth displacement electrode substrate Ed5 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the fifth capacitive element C5 is Becomes relatively small. Similarly, the amount of increase in the capacitance value of the sixth capacitive element C6 becomes relatively small.

The fourth strain body 30D is elastically deformed in the same way as the first strain body 30A shown in FIG. Decrease. More specifically, the second connection structure portion 32 of the fourth strain body 30D rotates clockwise and tilts when viewed toward the positive side in the Y-axis direction. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the fourth strain body 30D and the fixed body 25. Since the distance in the X-axis direction (corresponding to L2 in FIG. 6) between the center of the seventh displacement electrode substrate Ed7 and the central axis CL is relatively large, the seventh displacement electrode substrate Ed7 moves away from the seventh fixed electrode substrate Ef7. The amount of displacement is relatively large. Therefore, when the force Fx acts on the force receiving body 20 in the positive direction of the X-axis, the amount of decrease in the capacitance value of the seventh capacitive element C7 becomes relatively large. Therefore, C7 in the Fx row in the table shown in FIG. 12 is set to "--". Since the amount of decrease in the capacitance value of the eighth capacitive element C8 is also relatively large, C8 in the Fx row in the table shown in FIG. 12 is set as "--".

(When +Fy acts)
Next, a case where force Fy acts on the force receiving body 20 on the positive side in the Y-axis direction will be described. Also in the following description, the symbols in the table of FIG. 12 are determined according to the change in capacitance value as described above.

The first flexural body 30A is elastically deformed in the same way as the first flexural body 30A shown in FIG. Decrease. More specifically, the second connection structure portion 32 of the first strain body 30A rotates counterclockwise and tilts when viewed toward the positive side in the X-axis direction. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the first strain body 30A and the fixed body 25. Since the distance in the Y-axis direction (corresponding to L2 in FIG. 6) between the center of the first displacement electrode substrate Ed1 and the central axis CL is relatively large, the first displacement electrode substrate Ed1 moves away from the first fixed electrode substrate Ef1. The amount of displacement is relatively large. Therefore, when the force Fy acts on the force receiving body 20 in the positive direction of the Y-axis, the amount of decrease in the capacitance value of the first capacitive element C1 becomes relatively large. Therefore, C1 in the Fy row in the table shown in FIG. 12 is set to "--". Since the amount of decrease in the capacitance value of the second capacitive element C2 is also relatively large, C2 in the Fy row in the table shown in FIG. 12 is set as "--".

The second strain body 30B is elastically deformed in the same way as the first strain body 30A shown in FIG. Decrease. In this case, since the distance in the Y-axis direction (corresponding to L1 in FIG. 6) between the center of the third displacement electrode substrate Ed3 and the central axis CL is relatively small, the amount of increase in the capacitance value of the third capacitive element C3 is Becomes relatively small. Similarly, the amount of decrease in the capacitance value of the fourth capacitive element C4 becomes relatively small.

The third flexural body 30C is elastically deformed in the opposite direction to the first flexural body 30A shown in FIG. The value increases. More specifically, the second connection structure portion 32 of the third strain body 30C rotates counterclockwise and tilts when viewed toward the positive side in the X-axis direction. In this case, roughly, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the third strain body 30C and the fixed body 25. Since the distance in the Y-axis direction (corresponding to L2 in FIG. 6) between the center of the fifth displacement electrode substrate Ed5 and the central axis CL is relatively large, the fifth displacement electrode substrate Ed5 approaches the fifth fixed electrode substrate Ef5. The amount of displacement is relatively large. Therefore, when the force Fy acts on the force receiving body 20 in the positive direction of the Y-axis, the amount of increase in the capacitance value of the fifth capacitive element C5 becomes relatively large. Therefore, C5 in the Fy row in the table shown in FIG. 12 is set to "++". Since the amount of increase in the capacitance value of the sixth capacitive element C6 is also relatively large, C6 in the Fy row in the table shown in FIG. 12 is set as "++".

The fourth strain body 30D is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases. In this case, since the distance in the Y-axis direction (corresponding to L1 in FIG. 6) between the center of the seventh displacement electrode substrate Ed7 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the seventh capacitive element C7 is Becomes relatively small. Similarly, the amount of increase in the capacitance value of the eighth capacitive element C8 becomes relatively small.

(When +Fz acts)
Next, a case will be described in which a force Fz is applied to the force receiving body 20 on the positive side in the Z-axis direction. Also in the following description, the symbols in the table of FIG. 12 are determined according to the change in capacitance value as described above.

In this case, the first flexural body 30A is elastically deformed in the same manner as the first flexural body 30A shown in FIG. Capacitance value decreases. More specifically, the 22nd connection portion 38 of the first strain body 30A is inclined. Since the distance in the Y-axis direction (corresponding to L2 in FIG. 6) between the center of the first displacement electrode substrate Ed1 and the central axis CL is relatively large, the first displacement electrode substrate Ed1 moves away from the first fixed electrode substrate Ef1. The amount of displacement is relatively large. Therefore, C1 in the Fz row in the table shown in FIG. 12 is set to "--". Similarly, each of the second to eighth capacitive elements C2 to C8 also decreases relatively greatly.

(When +Mx acts)
Next, a case will be described in which a clockwise moment Mx (see FIG. 7) acts on the force receiving body 20 around the X-axis, that is, toward the positive side in the X-axis direction. Also in the following description, the symbols in the table of FIG. 12 are determined according to the change in capacitance value as described above.

In this case, the first strain body 30A is elastically deformed in the same manner as the first strain body 30A on which the force Fz directed toward the positive side in the Z-axis direction acts, as shown in FIG. 10A, and the electrostatic charge of the first capacitive element C1 is As the capacitance value decreases, the capacitance value of the second capacitive element C2 also decreases. As described above, since the distance in the Y-axis direction (corresponding to L2 in FIG. 6) between the center of the first displacement electrode substrate Ed1 and the central axis CL is relatively large, the first displacement electrode substrate Ed1 is the first fixed electrode substrate. The amount of displacement in the direction away from Ef1 is relatively large. Therefore, the amount of decrease in the capacitance value of the first capacitive element C1 becomes relatively large. Further, the distance in the Y-axis direction (corresponding to L3 in FIG. 3) between the center of the first displacement electrode substrate Ed1 and the center O of the force receiving body 20 is the same as the distance between the center of the third displacement electrode substrate Ed3 and the center O of the force receiving body 20. Since this distance is larger than the distance in the Y-axis direction (corresponding to L1 in FIG. 6), the amount of decrease in the capacitance value of the first capacitive element C1 becomes even larger. Similarly, the amount of decrease in capacitance value of the second capacitive element C2 becomes relatively large.

In the second strain body 30B, when viewed toward the positive side in the X-axis direction, the first connection structure section 31, the second connection structure section 32, and the third connection structure section 33 rotate clockwise. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the second strain body 30B and the fixed body 25. Therefore, the third displacement electrode substrate Ed3 moves away from the third fixed electrode substrate Ef3, and the inter-electrode distance between the third displacement electrode substrate Ed3 and the third fixed electrode substrate Ef3 increases. Therefore, the capacitance value of the third capacitive element C3 decreases. Since the distance in the Y-axis direction (corresponding to L1 in FIG. 6) between the center of the third displacement electrode substrate Ed3 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the third capacitive element C3 is relatively small. Become. On the other hand, the fourth displacement electrode substrate Ed4 approaches the fourth fixed electrode substrate Ef4, and the inter-electrode distance between the fourth displacement electrode substrate Ed4 and the fourth fixed electrode substrate Ef4 decreases. Therefore, the capacitance value of the fourth capacitive element C4 increases. Since the distance in the Y-axis direction (corresponding to L1 in FIG. 6) between the center of the fourth displacement electrode substrate Ed4 and the central axis CL is relatively small, the amount of increase in the capacitance value of the fourth capacitive element C4 is relatively small. Become.

As shown in FIG. 10B, the third strain body 30C is elastically deformed in the same manner as the first strain body 30A to which the force Fz directed toward the negative side in the Z-axis direction is applied, and the capacitance value of the fifth capacitive element C5 is As the capacitance increases, the capacitance value of the sixth capacitive element C6 also increases. As described above, since the distance in the Y-axis direction (corresponding to L2 in FIG. 6) between the center of the fifth displacement electrode substrate Ed5 and the central axis CL is relatively large, the fifth displacement electrode substrate Ed5 is the fifth fixed electrode substrate. The amount of displacement in the direction approaching Ef5 is relatively large. Therefore, the amount of increase in the capacitance value of the fifth capacitive element C5 becomes relatively large. Further, the distance in the Y-axis direction (corresponding to L3 in FIG. 3) between the center of the fifth displacement electrode substrate Ed5 and the center O of the force receiving body 20 is the same as the distance between the center of the fourth displacement electrode substrate Ed4 and the center O of the force receiving body 20. Since the distance in the Y-axis direction (corresponding to L1 in FIG. 6) is larger than that of the fifth capacitive element C5, the amount of increase in the capacitance value of the fifth capacitive element C5 becomes even larger. Similarly, the amount of increase in the capacitance value of the sixth capacitive element C6 is relatively large.

In the fourth strain body 30D, when viewed toward the positive side in the X-axis direction, the first connection structure section 31, the second connection structure section 32, and the third connection structure section 33 rotate clockwise. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the fourth strain body 30D and the fixed body 25. Therefore, the seventh displacement electrode substrate Ed7 approaches the seventh fixed electrode substrate Ef7, and the inter-electrode distance between the seventh displacement electrode substrate Ed7 and the seventh fixed electrode substrate Ef7 decreases. Therefore, the capacitance value of the seventh capacitive element C7 increases. Since the distance in the Y-axis direction (corresponding to L1 in FIG. 6) between the center of the seventh displacement electrode substrate Ed7 and the central axis CL is relatively small, the amount of increase in the capacitance value of the seventh capacitive element C7 is relatively small. Become. On the other hand, the eighth displacement electrode substrate Ed8 moves away from the eighth fixed electrode substrate Ef8, and the inter-electrode distance between the eighth displacement electrode substrate Ed8 and the eighth fixed electrode substrate Ef8 increases. Therefore, the capacitance value of the eighth capacitive element C8 decreases. Since the distance in the Y-axis direction (corresponding to L1 in FIG. 6) between the center of the eighth displacement electrode substrate Ed8 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the eighth capacitive element C8 is relatively small. Become.

(When +My acts)
Next, a case will be described in which a clockwise moment My (see FIG. 7) acts on the force receiving body 20 around the Y-axis, that is, toward the positive side in the Y-axis direction. Also in the following description, the symbols in the table of FIG. 12 are determined according to the change in capacitance value as described above.

In this case, when the first strain body 30A is viewed toward the positive side in the Y-axis direction, the first connection structure portion 31, the second connection structure portion 32, and the third connection structure portion 33 rotate clockwise. do. In this case, roughly speaking, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the first strain body 30A and the fixed body 25. Therefore, the first displacement electrode substrate Ed1 approaches the first fixed electrode substrate Ef1, and the inter-electrode distance between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 decreases. Therefore, the capacitance value of the first capacitive element C1 increases. Since the distance in the X-axis direction (corresponding to L1 in FIG. 6) between the center of the first displacement electrode substrate Ed1 and the central axis CL is relatively small, the amount of increase in the capacitance value of the first capacitive element C1 is relatively small. Become. On the other hand, the second displacement electrode substrate Ed2 moves away from the second fixed electrode substrate Ef2, and the inter-electrode distance between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 increases. Therefore, the capacitance value of the second capacitive element C2 decreases. Since the distance in the X-axis direction (corresponding to L1 in FIG. 6) between the center of the second displacement electrode substrate Ed2 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the second capacitive element C2 is relatively small. Become.

As shown in FIG. 10A, the second strain body 30B is elastically deformed in the same manner as the first strain body 30A to which the force Fz directed toward the positive side in the Z-axis direction is applied, and the capacitance value of the third capacitive element C3 is Along with this decrease, the capacitance value of the fourth capacitive element C4 also decreases. As described above, since the distance in the X-axis direction (corresponding to L2 in FIG. 6) between the center of the third displacement electrode substrate Ed3 and the central axis CL is relatively large, the third displacement electrode substrate Ed3 is the third fixed electrode substrate. The amount of displacement in the direction away from Ef3 is relatively large. Therefore, the amount of decrease in the capacitance value of the third capacitive element C3 becomes relatively large. Furthermore, the distance in the X-axis direction (corresponding to L3 in FIG. 3) between the center of the third displacement electrode substrate Ed3 and the center O of the force receiving body 20 is the same as the distance between the center of the second displacement electrode substrate Ed2 and the center O of the force receiving body 20. (corresponding to L1 in FIG. 6), the amount of decrease in the capacitance value of the third capacitive element C3 becomes even larger. Similarly, the amount of decrease in the capacitance value of the fourth capacitive element C4 becomes relatively large.

In the third strain body 30C, when viewed toward the positive side in the Y-axis direction, the first connection structure section 31, the second connection structure section 32, and the third connection structure section 33 rotate clockwise. In this case, roughly, the second connection structure 32 rotates around the connection point between the third connection structure 33 of the third strain body 30C and the fixed body 25. Therefore, the fifth displacement electrode substrate Ed5 moves away from the fifth fixed electrode substrate Ef5, and the inter-electrode distance between the fifth displacement electrode substrate Ed5 and the sixth fixed electrode substrate Ef6 increases. Therefore, the capacitance value of the fifth capacitive element C5 decreases. Since the distance in the X-axis direction (corresponding to L1 in FIG. 6) between the center of the fifth displacement electrode substrate Ed5 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the fifth capacitive element C5 is relatively small. Become. On the other hand, the sixth displacement electrode substrate Ed6 approaches the sixth fixed electrode substrate Ef6, and the inter-electrode distance between the sixth displacement electrode substrate Ed6 and the sixth fixed electrode substrate Ef6 decreases. Therefore, the capacitance value of the sixth capacitive element C6 increases. Since the distance in the X-axis direction (corresponding to L1 in FIG. 6) between the center of the sixth displacement electrode substrate Ed6 and the central axis CL is relatively small, the amount of increase in the capacitance value of the sixth capacitive element C6 is relatively small. Become.

As shown in FIG. 10B, the fourth strain body 30D is elastically deformed in the same manner as the first strain body 30A to which the force Fz directed toward the negative side in the Z-axis direction is applied, and the capacitance value of the seventh capacitive element C7 is As the capacitance increases, the capacitance value of the eighth capacitive element C8 also increases. As described above, since the distance in the X-axis direction (corresponding to L2 in FIG. 6) between the center of the seventh displacement electrode substrate Ed7 and the third connection structure portion 33 is relatively large, the seventh displacement electrode substrate Ed7 The amount of displacement in the direction approaching the fixed electrode substrate Ef7 is relatively large. Therefore, the amount of increase in the capacitance value of the seventh capacitive element C7 becomes relatively large. Also, the distance in the X-axis direction between the center of the seventh displacement electrode substrate Ed7 and the center O of the force receiving body 20 (corresponding to L3 in FIG. 3) is the same as the distance between the center of the sixth displacement electrode substrate Ed6 and the center O of the force receiving body 20. (corresponding to L1 in FIG. 6), the amount of increase in the capacitance value of the seventh capacitive element C7 becomes even larger. Similarly, the amount of increase in the capacitance value of the eighth capacitive element C8 becomes relatively large.

(When +Mz acts)
Next, a case will be described in which a clockwise moment Mz (see FIG. 7) is applied to the force receiving body 20 around the Z-axis, that is, toward the positive side in the Z-axis direction. Also in the following description, the symbols in the table of FIG. 12 are determined according to the change in capacitance value as described above.

In this case, the first flexural body 30A is elastically deformed in the opposite direction to the first flexural body 30A shown in FIG. The capacitance value increases. In this case, since the distance in the X-axis direction (corresponding to L1 in FIG. 6) between the center of the first displacement electrode substrate Ed1 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the first capacitive element C1 is Becomes relatively small. Similarly, the amount of increase in the capacitance value of the second capacitive element C2 becomes relatively small.

The second strain body 30B is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases. In this case, since the distance in the Y-axis direction (corresponding to L1 in FIG. 6) between the center of the third displacement electrode substrate Ed3 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the third capacitive element C3 is Becomes relatively small. Similarly, the amount of increase in the capacitance value of the fourth capacitive element C4 becomes relatively small.

The third strain body 30C is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases. In this case, since the distance in the X-axis direction (corresponding to L1 in FIG. 6) between the center of the fifth displacement electrode substrate Ed5 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the fifth capacitive element C5 is Becomes relatively small. Similarly, the amount of increase in the capacitance value of the sixth capacitive element C6 becomes relatively small.

The fourth strain body 30D is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases. In this case, since the distance in the Y-axis direction (corresponding to L1 in FIG. 6) between the center of the seventh displacement electrode substrate Ed7 and the central axis CL is relatively small, the amount of decrease in the capacitance value of the seventh capacitive element C7 is Becomes relatively small. Similarly, the amount of increase in the capacitance value of the eighth capacitive element C8 becomes relatively small.

In this way, when a change in the capacitance value of each capacitive element C1 to C8 is detected, the direction and magnitude of the force or moment acting on the force receiving body 20 is detected. Then, as shown in FIG. 12, the capacitance value of each capacitive element C1 to C8 changes.

From the table shown in FIG. 12, the forces Fx, Fy, Fz and moments Mx, My, Mz acting on the force receiving body 20 can be calculated using the following formulas. Thereby, six axial components of force can be detected. In addition, in the following formula, for convenience, force or moment and the amount of change in capacitance value are connected with "=". However, since the force or moment and the capacitance value are different physical quantities, in reality, the force or moment is calculated by converting the amount of change in the capacitance value. C1 to C8 in the following formulas indicate the amount of change in capacitance value in each capacitive element.

As described above, the force sensor 10 shown in FIG. This makes it possible to detect six-axis components of force. However, the number of axial components of force that can be detected by the force sensor 10 is not limited to six, and the number of axial components that can be detected is arbitrary depending on the number, structure, and shape of the strain body. It is. The coefficients a1 to a24 included in equations (4) to (9) above are coefficients indicating that the amount of change (increase or decrease) in the capacitance value is relatively small. Coefficients a1 to a24 may be different from each other.

Since the coefficients a1 to a24 are included in the above-mentioned equations (4) to (9), other axis sensitivity occurs in each axis component. However, even when other-axis sensitivity occurs, correction calculation can be performed by finding the inverse matrix of the other-axis sensitivity matrix and multiplying the output (characteristic matrix) of the force sensor by this inverse matrix. As a result, the other axis sensitivity can be reduced, and the other axis sensitivity can be reduced to such an extent that the occurrence of the other axis sensitivity can be ignored.

As described above, according to the present embodiment, each of the strain-generating bodies 30A to 30D is arranged at different positions in the circumferential direction with respect to the center O of the force-receiving body 20 when viewed in the Z-axis direction. When viewed in the Z-axis direction, each of the strain-generating bodies 30A to 30D is arranged such that the second direction extends outward from the center O of the force-receiving body 20. Thereby, the external dimensions of the force sensor 10 when viewed in the Z-axis direction can be reduced, and the size of the force sensor 10 can be reduced. For example, when the force receiving body 20 and the fixed body 25 are formed in a circular shape, the diameters of the force receiving body 20 and the fixed body 25 can be made small. Further, for example, when the strain bodies 30A to 30D are arranged such that the second direction is along a direction perpendicular to the radial direction with respect to the center O of the force receiving body 20 (a direction corresponding to the circumferential direction), The diameters of the force receiving body 20 and the fixed body 25 can be increased. However, according to the present embodiment, each of the strain bodies 30A to 30D is arranged such that the second direction extends outward from the center O of the force receiving body 20, so that the force sensor 10 External dimensions can be reduced.

Further, according to the present embodiment, the displacement electrode substrate for the first strain body 30A of the detection element 70 is arranged on one side with respect to the central axis CL of the first strain body 30A in the X-axis direction. It includes a first displacement electrode substrate Ed1 and a second displacement electrode substrate Ed2 arranged on the other side with respect to the central axis CL. Similarly, the displacement electrode substrates for the second to fourth strain-generating bodies 30B to 30D include third to eighth displacement electrode substrates Ed3 to Ed8. As a result, the number of detectable axis components can be increased, and the performance of the force sensor 10 can be improved.

Further, according to the present embodiment, when viewed in the Z-axis direction, the second connection structure portion 32 of each strain body 30A to 30D is closer to the force receiving body 20 than the corresponding first connection structure portion 31. It is located close to the center O. Thereby, each of the displacement electrode substrates Ed1 to Ed8 can be arranged at a position close to the center O of the force receiving body 20. Therefore, in the outer region of the force receiving body 20, a space can be secured between the two adjacent strain generating bodies 30A to 30D, and a space can be provided in this space to prevent damage to the force sensor 10 in the event of overload. A mechanism such as a stopper (not shown) may be provided. As a result, the force sensor 10 can be made smaller and the performance of the force sensor 10 can be improved.

Further, according to the present embodiment, when viewed in the Z-axis direction, the second direction of each strain body 30A to 30D is arranged radially with respect to the center O of the force receiving body 20. As a result, each of the displacement electrode substrates Ed1 to Ed8 of the detection element 70 can be arranged evenly in the circumferential direction with respect to the center O of the force receiving body 20. Therefore, the detection accuracy of the force or moment of each axis component can be improved, and the performance of the force sensor 10 can be improved.

Further, according to the present embodiment, the force receiving body 20 and the fixed body 25 are connected by four strain bodies 30A to 30D. Thereby, when viewed in the Z-axis direction, the four strain bodies 30A to 30D can be arranged along the X-axis direction and the Y-axis direction. Therefore, the detection accuracy of the force or moment of each axis component can be improved, and the performance of the force sensor 10 can be improved.

Further, according to the present embodiment, each of the displacement electrode substrates Ed1 to Ed8 is connected to the surface facing the fixed body 25 of the 21st connection portion 37 extending from the force receiving body 20 toward the fixed body 25. . This allows each of the displacement electrode substrates Ed1 to Ed8 to be easily opposed to the corresponding fixed electrode substrates Ef1 to Ef8.

Further, according to the present embodiment, the displacement section 41 is connected to the surface of the second connection structure section 32 facing the fixed body 25, and the corresponding displacement electrode is connected to the surface of the displacement section 41 facing the fixed body 25. Boards Ed1 to Ed8 are connected. This allows each of the displacement electrode substrates Ed1 to Ed8 to be brought closer to the corresponding fixed electrode substrates Ef1 to Ef8. Therefore, the detection sensitivity can be improved, and the performance of the force sensor 10 can be improved.

Further, according to the present embodiment, the eleventh connection part 34 of the first connection structure part 31 and the twenty-first connection part 37 of the second connection structure part 32 extend in the Z-axis direction, and the first connection structure part The twelfth connecting portion 35 of No. 31 and the twenty-second connecting portion 38 of the second connecting structure portion 32 extend in the second direction (X-axis direction or Y-axis direction). As a result, when force or moment is applied to the force receiving body 20, the first connection structure section 31 and the second connection structure section 32 are elastically deformed in any of the X-axis direction, Y-axis direction, and Z-axis direction. be able to. Therefore, the detection sensitivity of the force sensor 10 can be improved.

Further, according to the present embodiment, the distance L2 in the second direction between each of the displacement electrode substrates Ed1 to Ed8 and the center axis CL of the corresponding strain body 30A to 30D is It is larger than the distance L1 in the third direction from the corresponding central axis CL. As a result, when the first connection structure section 31, the second connection structure section 32, and the third connection structure section 33 rotate within the plane along the first direction and the second direction, the capacitance of the corresponding capacitance element The amount of change in value can be increased. Therefore, the detection sensitivity can be improved, and the performance of the force sensor 10 can be improved.

In the present embodiment described above, an example has been described in which the displacement electrode substrates Ed1 to Ed8 are connected to the displacement portion 41. However, this embodiment is not limited to this. For example, each of the strain-generating bodies 30A to 30D may not include the displacement portion 41. In this case, the displacement electrode substrates Ed1 to Ed8 may be connected to the surface of the 21st connection section 37 of the corresponding second connection structure section 32 that faces the fixed body 25. Alternatively, the displacement electrode substrates Ed1 to Ed8 may be connected to the surface of the 22nd connection portion 38 of the corresponding second connection structure 32 facing the fixed body 25.

Further, in the present embodiment described above, when viewed in the Z-axis direction, the second connection structure portion 32 of each strain body 30A to 30D is closer to the force receiving body than the corresponding first connection structure portion 31. An example has been described in which the device is placed near the center O of 20. However, this embodiment is not limited to this. For example, the first connection structure portion 31 of each of the strain-generating bodies 30A to 30D may be located closer to the center O of the force receiving body 20 than the corresponding second connection structure portion 32. In this case as well, each of the strain-generating bodies 30A to 30D is arranged so that the second direction extends outward from the center O of the force-receiving body 20 when viewed in the Z-axis direction. , the external dimensions of the force sensor 10 can be reduced.

Furthermore, in the present embodiment described above, an example has been described in which the capacitive element for the first strain body 30A is constituted by the first capacitive element C1 and the second capacitive element C2. However, this embodiment is not limited to this. For example, the capacitive element for the first strain body 30A may be constituted by one capacitive element. In this case, the capacitive element for the first strain body 30A may include one displacement electrode substrate and one fixed electrode substrate. The same applies to the capacitive element for the second flexural body 30B, the capacitive element for the third flexural body 30C, and the capacitive element for the fourth flexural body 30D.

Furthermore, in the present embodiment described above, an example has been described in which the first connection structure section 31 includes the eleventh connection section 34 and the twelfth connection section 35. However, the structure of the first connection structure section 31 is not limited to this and is arbitrary. The same applies to the second connection structure section 32.

Furthermore, in the present embodiment described above, an example has been described in which the distance L1 in the X-axis direction shown in FIG. 6 is larger than the distance L2 in the Y-axis direction. However, the distance L1 in the X-axis direction may be equal to the distance L2 in the Y-axis direction, or may be smaller than the distance L2 in the Y-axis direction.

(Second embodiment)
Next, a force sensor according to a second embodiment of the present invention will be described using FIGS. 13 to 15.

The second embodiment shown in FIGS. 13 to 15 differs mainly in that the spring constant of the second connection structure is smaller than the spring constant of the first connection structure. The other configurations are substantially the same as the first embodiment shown in FIGS. 1 to 12. Note that in FIGS. 13 to 15, the same parts as in the first embodiment shown in FIGS. 1 to 12 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 13 is a side view showing the first strain body of the force sensor according to the second embodiment. FIG. 14 is a plan view showing the first strain body of FIG. 13. FIG. 15 is a plan view showing a force sensor including the first strain body shown in FIGS. 13 and 14, with the force receiving body omitted.

As shown in FIGS. 13 and 14, in this embodiment, the spring constant of the second connection structure section 32 of the first strain body 30A is smaller than the spring constant of the first connection structure section 31. . More specifically, the spring constant of the second connection structure 32 is the same as that of the first connection structure for each of the force acting in the X-axis direction, the force acting in the Y-axis direction, and the force acting in the Z-axis direction. The spring constant may be smaller than the spring constant of the portion 31.

For example, the cross-sectional area of the twenty-first connecting portion 37 of the second connecting structure portion 32 may be smaller than the cross-sectional area of the eleventh connecting portion 34 of the first connecting structure portion 31. In this case, the spring constant of the 21st connecting portion 37 can be made smaller than the spring constant of the 11th connecting portion 34. The cross-sectional area of the 21st connecting portion 37 and the cross-sectional area of the 11th connecting portion 34 are cross-sectional areas along the XY plane. For example, the Y-axis direction dimension of the 21st connection section 37 may be smaller than the Y-axis direction dimension of the 11th connection section 34, and/or the X-axis direction dimension of the 21st connection section 37 may be made smaller than the Y-axis direction dimension of the 11th connection section 34. The dimension in the X-axis direction may be smaller than the dimension in the X-axis direction. In this way, the spring constant of the second connection structure 32 is set to be higher than the spring constant of the first connection structure 31 for each of the force in the X-axis direction, the force in the Y-axis direction, and the force in the Z-axis direction. Can be made smaller.

For example, the cross-sectional area of the 22nd connecting part 38 of the 2nd connecting structure part 32 may be smaller than the cross-sectional area of the 12th connecting part 35 of the 1st connecting structure part 31. In this case, the spring constant of the second connecting portion 38 can be made smaller than the spring constant of the twelfth connecting portion 35. The cross-sectional area of the second connecting portion 38 and the cross-sectional area of the twelfth connecting portion 35 are cross-sectional areas along the XZ plane. For example, the Z-axis direction dimension of the 22nd connection part 38 may be smaller than the Z-axis direction dimension of the 12th connection part 35, and/or the X-axis direction dimension of the 22nd connection part 38 may be made smaller than the Z-axis direction dimension of the 2nd connection part 35. The dimension in the X-axis direction may be smaller than the dimension in the X-axis direction. In this way, the spring constant of the second connection structure 32 is set to be higher than the spring constant of the first connection structure 31 for each of the force in the X-axis direction, the force in the Y-axis direction, and the force in the Z-axis direction. Can be made smaller.

Similarly, the spring constant of the second connection structure portion 32 of the second strain body 30B to fourth strain body 30D may be smaller than the spring constant of the first connection structure portion 31.

As shown in FIG. 15, when viewed in the Z-axis direction, the four strain-generating bodies 30A to 30D are arranged such that the second direction extends outward from the center O of the force receiving body 20. . The spring constant of the second connection structure 32 of each strain body 30A to 30D is smaller than the spring constant of the first connection structure 31, and the second connection structure 32 is smaller than the spring constant of the first connection structure 31. It is arranged at a position closer to the center O of the force receiving body 20 than the center O of the force receiving body 20. As a result, when a moment Mx around the X axis, a moment My around the Y axis, or a moment Mz around the Z axis acts on the force receiving body 20, the stress acting on the first connection structure 31 and the second connection structure The difference between the stress acting on the portion 32 and the stress acting on the portion 32 can be reduced. That is, if the spring constant of the second connection structure 32 is not smaller than the spring constant of the first connection structure 31, the moment Mx, My, or Mz acting on the force receiving body 20 causes the second connection structure 32 to The applied stress may be greater than the stress applied to the first connection structure 31 . This may increase the difference between the stress acting on the first connection structure 31 and the stress acting on the second connection structure 32. On the other hand, according to the present embodiment, since the spring constant of the second connection structure 32 is smaller than the spring constant of the first connection structure 31, the moment Mx, My or Mz acts on the force receiving body 20. In this case, the difference between the stress acting on the first connection structure 31 and the stress acting on the second connection structure 32 can be reduced.

As described above, according to the present embodiment, the spring constant of the second connection structure section 32 is smaller than the spring constant of the first connection structure section 31. Thereby, the difference between the stress acting on the first connection structure section 31 and the stress acting on the second connection structure section 32 can be reduced. Therefore, the stress acting on the first connection structure 31 and the stress acting on the second connection structure 32 can be equalized, and the reliability of the force sensor 10 can be improved.

(Third embodiment)
Next, a force sensor according to a third embodiment of the present invention will be described using FIG. 16.

The third embodiment shown in FIG. 16 differs mainly in that the displacement electrode substrate protrudes from the second connection structure toward the center of the force receiving body when viewed in the Z-axis direction. The other configurations are substantially the same as the first embodiment shown in FIGS. 1 to 12. Note that in FIG. 16, the same parts as in the first embodiment shown in FIGS. 1 to 12 are given the same reference numerals, and detailed explanations will be omitted. FIG. 16 is a plan view showing a displacement electrode of a force sensor according to the third embodiment.

As shown in FIG. 16, the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 of the detection element 70 are received from the second connection structure portion 32 of the first strain body 30A when viewed in the Z-axis direction. It protrudes toward the center O of the force body 20. The displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 protrude from the second connection structure portion 32 toward the negative side in the Y-axis direction. The first displacement electrode substrate Ed1 may protrude from the second connection structure 32 in the positive direction of the X-axis, and the second displacement electrode substrate Ed2 may protrude from the second connection structure 32 in the negative direction of the X-axis. It's okay. The displacement electrode Ed of the first displacement electrode substrate Ed1 may be formed in a tapered shape toward the center O. This can prevent the first displacement electrode substrate Ed1 from interfering with the eighth displacement electrode substrate Ed8. Similarly, the displacement electrode Ed of the second displacement electrode substrate Ed2 may be formed in a tapered shape toward the center O. This can prevent the second displacement electrode substrate Ed2 from interfering with the third displacement electrode substrate Ed3. The tip of the displacement electrode Ed of the first displacement electrode substrate Ed1 and the tip of the displacement electrode Ed of the second displacement electrode substrate Ed2 are arranged on the positive side of the center O in the Y-axis direction. In this way, it is possible to prevent the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 from interfering with other displacement electrode substrates.

The displacement portion 41 may be attached to the common insulator IBdc of the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 using bolts. A screw hole 42 into which a bolt is screwed may be formed on the surface of the displacement section 41 facing the fixed body 25 (corresponding to the lower surface of the displacement section 41 in FIG. 4). The displacement electrodes Ed of the first displacement electrode substrate Ed1 and the displacement electrodes Ed of the second displacement electrode substrate Ed2 may each be cut out so as not to overlap with the screw holes 42.

As shown in FIG. 16, the third displacement electrode substrate Ed3 and the fourth displacement electrode substrate Ed4 of the detection element 70 are received from the second connection structure portion 32 of the second strain body 30B when viewed in the Z-axis direction. It protrudes toward the center O of the force body 20. The displacement electrode Ed of the third displacement electrode substrate Ed3 and the displacement electrode Ed of the fourth displacement electrode substrate Ed4 protrude from the second connection structure portion 32 toward the positive side in the X-axis direction. The third displacement electrode substrate Ed3 may protrude from the second connection structure 32 in the positive direction of the Y-axis, and the fourth displacement electrode substrate Ed4 may protrude from the second connection structure 32 in the negative direction of the Y-axis. It's okay. The tip of the displacement electrode Ed of the third displacement electrode substrate Ed3 and the tip of the displacement electrode Ed of the fourth displacement electrode substrate Ed4 are arranged on the negative side of the center O in the X-axis direction. The third displacement electrode substrate Ed3 and the fourth displacement electrode substrate Ed4 are formed similarly to the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2. In this way, it is possible to prevent the third displacement electrode substrate Ed3 and the fourth displacement electrode substrate Ed4 from interfering with other displacement electrode substrates.

As shown in FIG. 16, the fifth displacement electrode substrate Ed5 and the sixth displacement electrode substrate Ed6 of the detection element 70 are received from the second connection structure portion 32 of the third strain body 30C when viewed in the Z-axis direction. It protrudes toward the center O of the force body 20. The displacement electrodes Ed of the fifth displacement electrode substrate Ed5 and the displacement electrodes Ed of the sixth displacement electrode substrate Ed6 protrude from the second connection structure portion 32 toward the positive side in the Y-axis direction. The fifth displacement electrode substrate Ed5 may protrude from the second connection structure 32 in the negative direction of the X-axis, and the sixth displacement electrode substrate Ed6 may protrude from the second connection structure 32 in the positive direction of the X-axis. It's okay. The tip of the displacement electrode Ed of the fifth displacement electrode substrate Ed5 and the tip of the displacement electrode Ed of the sixth displacement electrode substrate Ed6 are arranged on the negative side of the center O in the Y-axis direction. The fifth displacement electrode substrate Ed5 and the sixth displacement electrode substrate Ed6 are formed similarly to the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2. In this way, it is possible to prevent the fifth displacement electrode substrate Ed5 and the sixth displacement electrode substrate Ed6 from interfering with other displacement electrode substrates.

As shown in FIG. 16, the seventh displacement electrode substrate Ed7 and the eighth displacement electrode substrate Ed8 of the detection element 70 are received from the second connection structure portion 32 of the fourth strain body 30D when viewed in the Z-axis direction. It protrudes toward the center O of the force body 20. The displacement electrode Ed of the seventh displacement electrode substrate Ed7 and the displacement electrode Ed of the eighth displacement electrode substrate Ed8 protrude from the second connection structure portion 32 toward the negative side in the X-axis direction. The seventh displacement electrode substrate Ed7 may protrude from the second connection structure 32 in the negative direction of the Y-axis, and the eighth displacement electrode substrate Ed8 may protrude from the second connection structure 32 in the positive direction of the Y-axis. It's okay. The tips of the displacement electrodes Ed of the seventh displacement electrode substrate Ed7 and the tips of the displacement electrodes Ed of the eighth displacement electrode substrate Ed8 are arranged on the negative side of the center O in the Y-axis direction. The seventh displacement electrode substrate Ed7 and the eighth displacement electrode substrate Ed8 are formed similarly to the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2. In this way, it is possible to prevent the seventh displacement electrode substrate Ed7 and the eighth displacement electrode substrate Ed8 from interfering with other displacement electrode substrates.

As described above, according to the present embodiment, each of the displacement electrode substrates Ed1 to Ed8 of the detection element 70 moves from the corresponding second connection structure 32 to the center O of the force receiving body 20 when viewed in the Z-axis direction. protruding towards. As a result, the planar area of the displacement electrodes Ed of the displacement electrode substrates Ed1 to Ed8 can be increased, and the capacitance value of each of the capacitive elements C1 to C8 can be increased. Therefore, the detection sensitivity can be improved, and the performance of the force sensor 10 can be improved.

(Fourth embodiment)
Next, a force sensor according to a fourth embodiment of the present invention will be described using FIG. 17.

In the fourth embodiment shown in FIG. 17, the first connection structure includes a first buffer structure that buffers the force acting on the strain-generating body, and the second connection structure includes a strain-generating body. The main difference is that it includes a second buffer structure that buffers the force acting on the body. The other configurations are substantially the same as the second embodiment shown in FIGS. 13 to 15. Note that in FIG. 17, the same parts as those in the second embodiment shown in FIGS. 13 to 15 are designated by the same reference numerals, and detailed description thereof will be omitted. FIG. 17 is a side view showing the first strain body of the force sensor according to the fourth embodiment.

As shown in FIG. 17, the first connection structure section 31 of the first strain body 30A according to this embodiment may include a first buffer structure section 43. The first buffer structure portion 43 is configured to buffer the force that acts on the first strain body 30A when force or moment acts on the force receiving body 20. One end of the first buffer structure 43 is connected to the eleventh connection part 34 and the other end is connected to the twelfth connection part 35. The first buffer structure portion 43 may be formed into a generally rectangular shape when viewed in the X-axis direction.

A space 44 is formed between the first connection structure 31 and the second connection structure 32 of the first strain body 30A shown in FIG. 17 . When viewed in the X-axis direction, the first buffer structure 43 may be formed such that the space 44 bulges on the side opposite to the second connection structure 32 in the Y-axis direction.

The space portion 44 may include a space main body portion 44a and a first bulge portion 44b. The space main body part 44a mainly connects the 11th connection part 34 and the 12th connection part 35 of the 1st connection structure part 31, the 21st connection part 37 and the 22nd connection part 38 of the 2nd connection structure part 32, and This is a space defined by the body 20.

The first bulging portion 44b is a space formed by the first buffer structure portion 43 so as to bulge out from the space main body portion 44a. The first bulging portion 44b bulges out from the space main body portion 44a toward the negative side in the Y-axis direction. The space main body portion 44a and the first bulging portion 44b communicate with each other, and the eleventh connecting portion 34 and the twelfth connecting portion 35 are separated. The first bulging portion 44b shown in FIG. 17 bulges toward the fixed body 25 in the Z-axis direction, and also bulges toward the side opposite to the second connection structure portion 32 in the Y-axis direction. A structural portion 43 may be formed. The first bulging portion 44b bulges out from the space body portion 44a toward the negative side in the Z-axis direction and also toward the negative side in the Y-axis direction.

The first buffer structure section 43 of the first strain body 30A according to the example shown in FIG. May contain. The first bulging portion 44b described above is a space mainly defined by the eleventh buffer portion 45, the twelfth buffer portion 46, the thirteenth buffer portion 47, and the fourteenth buffer portion 48.

The eleventh buffer section 45 may extend from the end of the eleventh connection section 34 on the negative side in the Z-axis direction to the positive side in the Y-axis direction. The eleventh buffer section 45 may extend in the Y-axis direction. The twelfth buffer section 46 may extend from the end of the eleventh buffer section 45 on the negative side in the Y-axis direction to the negative side in the Z-axis direction. The twelfth buffer section 46 may extend in the Z-axis direction. The thirteenth buffer section 47 may extend from the end of the twelfth buffer section 46 on the negative side in the Z-axis direction to the positive side in the Y-axis direction. The thirteenth buffer section 47 may extend in the Y-axis direction. The fourteenth buffer section 48 may extend from the end of the thirteenth buffer section 47 on the positive side in the Y-axis direction to the positive side in the Z-axis direction. The fourteenth buffer portion 48 may extend in the Z-axis direction. The fourteenth buffer section 48 may be connected to the end of the twelfth connection section 35 on the negative side in the Y-axis direction.

As shown in FIG. 17, the second connection structure section 32 of the first strain body 30A according to this embodiment may include a second buffer structure section 49. The second buffer structure portion 49 is configured to buffer the force acting on the first strain body 30A due to force or moment acting on the force receiving body 20. One end of the second buffer structure section 49 is connected to the twenty-first connecting section 37, and the other end is connected to the twenty-second connecting section 38. The second buffer structure portion 49 may be formed in a rectangular shape when viewed in the X-axis direction.

When the space portion 44 described above is viewed in the X-axis direction, the second buffer structure portion 49 may be formed so as to bulge out to the side opposite to the first connection structure portion 31 in the Y-axis direction.

The above-described space portion 44 according to the present embodiment may further include a second bulge portion 44c. The second bulging portion 44c is a space formed by the second buffer structure portion 49 so as to bulge out from the space main body portion 44a. The second bulging portion 44c bulges out from the space main body portion 44a toward the positive side in the Y-axis direction. The space main body portion 44a and the second bulging portion 44c communicate with each other, and the 21st connection portion 37 and the 22nd connection portion 38 of the second connection structure portion 32 are separated.

The second buffer structure section 49 of the first strain body 30A according to the example shown in FIG. 17 may include a 21st buffer section 50, a 22nd buffer section 51, and a 23rd buffer section 52. The second bulging portion 44c described above is a space mainly defined by the 21st buffer portion 50, the 22nd buffer portion 51, and the 23rd buffer portion 52.

The 21st buffer portion 50 may extend from the end of the 21st connection portion 37 on the negative side in the Z-axis direction to the negative side in the Y-axis direction. The 21st buffer section 50 may extend in the Y-axis direction. The 22nd buffer part 51 may extend from the end of the 21st buffer part 50 on the negative side in the Y-axis direction to the negative side in the Z-axis direction. The 22nd buffer portion 51 may extend in the Z-axis direction. The 23rd buffer section 52 may extend from the end of the 22nd buffer section 51 on the negative side in the Z-axis direction to the positive side in the Y-axis direction. The 23rd buffer portion 52 may extend in the Y-axis direction. The 23rd buffer section 52 may be connected to the end of the 22nd connection section 38 on the negative side in the Y-axis direction. The 23rd buffer part 52 may be continuously formed on a straight line along the Y-axis direction with the 22nd connection part 38. The 23rd buffer portion 52 is a portion that defines the second bulging portion 44c described above, and the 22nd connecting portion 38 is a portion that defines the space main body portion 44a described above.

In the example shown in FIG. 17, the displacement part 41 may be connected to the second buffer structure part 49. More specifically, the displacement section 41 may be connected to the 22nd buffer section 51 of the second buffer structure section 49. The displacement section 41 may be connected to the surface of the second buffer section 51 that faces the fixed body 25 (the lower surface of the second buffer section 51 in FIG. 17). A portion of the displacement section 41 may be connected to a surface of the twenty-third buffer section 52 that faces the fixed body 25.

The spring constant of the third connection structure section 33 of the first strain body 30A according to the present embodiment may be larger than the spring constant of the first connection structure section 31 and the spring constant of the second connection structure section 32. The spring constant of the third connection structure 33 is the same as the spring constant of the first connection structure 31 for each of the force acting in the X-axis direction, the force acting in the Y-axis direction, and the force acting in the Z-axis direction. The spring constant may be larger than the spring constant of the second connection structure portion 32.

Similar to the first strain body 30A shown in FIGS. 13 and 14, the spring constant of the second connection structure 32 of the first strain body 30A according to the present embodiment is greater than the spring constant of the first connection structure 31. may also be small. The cross-sectional area of the twenty-first connecting portion 37 may be smaller than the cross-sectional area of the eleventh connecting portion 34. The cross-sectional area of the second connecting portion 38 may be smaller than the cross-sectional area of the twelfth connecting portion 35.

The spring constant of the second buffer structure 49 may be smaller than the spring constant of the first buffer structure 43. For example, the cross-sectional area of each of the buffer sections 50 to 52 of the second buffer structure section 49 may be smaller than the cross-sectional area of each of the buffer sections 45 to 48 of the first buffer structure section 43. For example, the second buffer structure 49 has a shape such that the spring constant of the second buffer structure 49 is smaller than the spring constant of the first buffer structure 43 when viewed in the X-axis direction. Good too.

As shown in FIG. 17, the first strain body 30A may further include a first pedestal 53 and a second pedestal 54. The first pedestal 53 is interposed between the force receiving body 20 and the first connection structure portion 31. The first connection structure section 31 is connected to the force receiving body 20 via the first pedestal 53. The second pedestal 54 is interposed between the force receiving body 20 and the second connection structure portion 32. The second connection structure portion 32 is connected to the force receiving body 20 via the second pedestal 54. The first pedestal 53 and the second pedestal 54 may each have relatively high rigidity. The first pedestal 53 may be formed separately from the first connection structure portion 31, or may be formed integrally with a continuous material. The second pedestal 54 may be formed separately from the second connection structure portion 32, or may be formed integrally with a continuous material.

The second strain body 30B to the fourth strain body 30D have the same configuration as the first strain body 30A.

When force or moment acts on the force sensor 10 according to the present embodiment, the first connection structure section 31 and the second connection structure section 32 are elastically deformed. At this time, the first buffer structure 43 absorbs and buffers the force acting on the first connection structure 31. Therefore, stress acting on the first connection structure portion 31 can be reduced. Similarly, the second buffer structure 49 absorbs and buffers the force acting on the second connection structure 32. Therefore, stress acting on the second connection structure portion 32 can be reduced.

When force or moment acts on the force sensor 10 according to the present embodiment, the third connection structure 33 does not substantially undergo elastic deformation because the spring constant of the third connection structure 33 is large. However, the eleventh buffer section 45 and the thirteenth buffer section 47 of the first buffer structure section 43 extend in the Y-axis direction, and the twelfth buffer section 46 and the fourteenth buffer section 48 extend in the Z-axis direction. As a result, even when the force Fx in the X-axis direction, the force Fy in the Y-axis direction, and the force Fz in the Z-axis direction act on the force receiving body 20, the first buffer structure 43 can be elastically deformed. This allows the displacement portion 41 to be displaced. Even when the moment Mx around the X axis, the moment My around the Y axis, and the moment Mz around the Z axis act on the force receiving body 20, the displacement portion 41 can be similarly displaced.

Similarly, the 21st buffer section 50 and the 23rd buffer section 52 of the second buffer structure section 49 extend in the Y-axis direction, and the 22nd buffer section 51 extends in the Z-axis direction. As a result, even if the force Fx in the X-axis direction, the force Fy in the Y-axis direction, and the force Fz in the Z-axis direction act on the force-receiving body 20, the second buffer structure 49 cannot be elastically deformed. This allows the displacement portion 41 to be displaced. Even when the moment Mx around the X axis, the moment My around the Y axis, and the moment Mz around the Z axis act on the force receiving body 20, the displacement portion 41 can be similarly displaced.

Changes in the capacitance values of the capacitive elements C1 to C8 when force or moment of each axial component acts on the force receiving body 20 are similar to the table shown in FIG. 12. A detailed explanation will be omitted here.

As described above, according to the present embodiment, the first connection structure section 31 of each of the strain bodies 30A to 30D includes the first buffer structure section 43 that buffers the force acting on the strain bodies 30A to 30D. There is. Thereby, stress acting on the first connection structure portion 31 can be reduced. Therefore, the reliability of the force sensor 10 can be improved. Further, the height dimension (Z-axis direction dimension) of the force sensor 10 can be reduced, and the height of the force sensor 10 can be reduced.

Further, according to the present embodiment, when viewed in the X-axis direction, the space portion 44 bulges on the side opposite to the second connection structure portion 32 of the first strain body 30A in the Y-axis direction. A first buffer structure 43 is formed. The first buffer structure portion 43 is similarly formed for the second to fourth strain bodies 30B to 30D. This makes it possible to enhance the force buffering effect of the first buffer structure 43 for each of the strain-generating bodies 30A to 30D. Therefore, the reliability and sensitivity of the force sensor 10 can be further improved. For example, if the first buffer structure 43 extends relatively long in the Y-axis direction as shown in FIG. It can be easily displaced. Therefore, the height of the force sensor 10 can be reduced, and the sensitivity of the force sensor 10 can be improved.

Further, according to the present embodiment, when viewed in the X-axis direction, the second connection structure portion 32 of the first strain body 30A bulges out toward the fixed body 25 in the Z-axis direction and in the Y-axis direction. The first buffer structure portion 43 is formed so as to bulge out on the opposite side. The first buffer structure portion 43 is similarly formed for the second to fourth strain bodies 30B to 30D. This makes it possible to enhance the force buffering effect of the first buffer structure 43 for each of the strain-generating bodies 30A to 30D. Therefore, the reliability and sensitivity of the force sensor 10 can be further improved.

Further, according to the present embodiment, the second connection structure section 32 of each of the flexure bodies 30A to 30D includes a second buffer structure section 49 that buffers the force acting on the flexure bodies 30A to 30D. . Thereby, stress acting on the second connection structure portion 32 can be reduced. Therefore, the reliability and sensitivity of the force sensor 10 can be improved. Moreover, the height dimension of the force sensor 10 can be reduced, and the height of the force sensor 10 can be reduced.

Further, according to the present embodiment, the second buffer structure 49 is configured such that the space 44 bulges on the side opposite to the first connection structure 31 in the Y-axis direction when viewed in the X-axis direction. It is formed. Similarly, second buffer structures 49 are formed for the second to fourth strain bodies 30B to 30D. This makes it possible to enhance the force buffering effect of the second buffer structure 49 for each of the strain-generating bodies 30A to 30D. Therefore, the reliability and sensitivity of the force sensor 10 can be further improved. For example, if the second buffer structure 49 extends relatively long in the Y-axis direction as shown in FIG. It can be easily displaced. Therefore, the height of the force sensor 10 can be reduced, and the sensitivity of the force sensor 10 can be improved.

Further, according to the present embodiment, the spring constant of the third connection structure section 33 of each of the strain bodies 30A to 30D is greater than the spring constant of the first connection structure section 31 and the spring constant of the second connection structure section 32. It's also big. Thereby, the stress acting on the third connection structure portion 33 can be increased. In this case, the stress acting on the first connection structure 31 and the stress acting on the second connection structure 32 can be reduced. Therefore, the reliability and sensitivity of the force sensor 10 can be improved. Furthermore, the height dimension of the force sensor 10 can be reduced, and the height of the force sensor 10 can be reduced.

In addition, in the present embodiment described above, when the first buffer structure 43 is viewed in the X-axis direction, the space 44 bulges on the side opposite to the second connection structure 32 in the Y-axis direction. An example of the structure has been explained. However, the first buffer structure portion 43 may be formed in any shape as long as it can buffer the force acting on the corresponding strain body 30A to 30D. The same applies to the second buffer structure section 49.

The present invention is not limited to the above-described embodiments and modifications as they are, but can be implemented by modifying the constituent elements within the scope of the invention at the implementation stage. Moreover, various inventions can be formed by appropriately combining the plurality of components disclosed in the above embodiments and modified examples. Some components may be deleted from all the components shown in the embodiments and modifications. Furthermore, components of different embodiments and modifications may be combined as appropriate.

10 Force sensor 20 Force receiving body 25 Fixed body 31 First connection structure section 32 Second connection structure section 33 Third connection structure section 34 Eleventh connection section 35 Twelfth connection section 36 First connection end section 37 Twenty-first connection section 38 22nd connection part 39 2nd connection end part 40 3rd connection end part 41 Displacement part 43 1st buffer structure part 44 Space part 49 2nd buffer structure part CL Central axis line

Claims (17)

a first sensor body subjected to the action of a force or moment to be detected;
a second sensor body disposed at a different position from the first sensor body in the first direction;
a plurality of strain-generating bodies connecting the first sensor body and the second sensor body and elastically deforming due to the action of force or moment received by the first sensor body;
a detection element that detects a change in capacitance value due to a displacement caused by elastic deformation of the strain body;
a detection circuit that outputs an electric signal indicating a force or moment acting on the first sensor body based on a detection result of the detection element;
Equipped with
The strain body includes a first connection structure connected to the first sensor body and a second connection structure connected to the first sensor body, and the strain body is arranged in a second direction perpendicular to the first direction. a second connection structure disposed at a different position from the first connection structure; and a third connection structure that connects the first connection structure and the second connection structure to the second sensor body. and a third connection structure disposed between the first connection structure and the second connection structure in the second direction,
The detection element includes a fixed electrode substrate provided on the second sensor body, and a displacement electrode substrate that is displaced together with the second connection structure and faces the fixed electrode substrate,
When viewed in the first direction, each of the strain-generating bodies is arranged at different positions in a circumferential direction with respect to the center of the first sensor body,
the strain-generating body is arranged such that the second direction is along a direction outward from the center of the first sensor body;
Force sensor. The displacement electrode substrate includes, in a third direction orthogonal to each of the first direction and the second direction, a one-side displacement electrode substrate disposed on one side with respect to the central axis of the flexure element; an other side displacement electrode substrate disposed on the other side with respect to the axis;
The force sensor according to claim 1. When viewed in the first direction, the second connection structure of each strain-generating body is located closer to the center of the first sensor body than the corresponding first connection structure. There is,
The force sensor according to claim 1 or 2. When viewed in the first direction, the second direction of each of the strain-generating bodies is arranged radially with respect to the center of the first sensor body.
The force sensor according to claim 1 or 2. The first sensor body and the second sensor body are connected by the four strain bodies,
The force sensor according to claim 4. The second connection structure includes a 21st connection part extending from the first sensor body toward the second sensor body, and a 22nd connection part that connects the third connection structure and the 21st connection part. , including;
The one-side displacement electrode substrate and the other-side displacement electrode substrate are connected to a surface of the 21st connection portion facing the second sensor body.
The force sensor according to claim 2. The strain body includes a displacement part connected to a surface of the second connection structure facing the second sensor body,
the one-side displacement electrode substrate and the other-side displacement electrode substrate are connected to a surface of the displacement section facing the second sensor body;
The force sensor according to claim 2. The first connection structure includes an eleventh connection part extending from the first sensor body toward the second sensor body, and a twelfth connection part connecting the third connection structure and the eleventh connection part. , including;
The second connection structure includes a 21st connection part extending from the first sensor body toward the second sensor body, and a 22nd connection part that connects the third connection structure and the 21st connection part. , including;
The eleventh connection part and the twenty-first connection part extend in the first direction,
the twelfth connecting portion and the twenty-second connecting portion extend in the second direction;
The force sensor according to claim 1 or 2. The distance in the second direction between the one-side displacement electrode substrate and the central axis of the strain-generating body is longer than the distance in the third direction between the one-side displacement electrode substrate and the central axis of the strain-generating body. big,
The force sensor according to claim 2. a spring constant of the second connection structure is smaller than a spring constant of the first connection structure;
The force sensor according to claim 1 or 2. The one-side displacement electrode substrate and the other-side displacement electrode substrate protrude from the second connection structure toward the center of the first sensor body when viewed in the first direction.
The force sensor according to claim 2. The first connection structure includes a first buffer structure that buffers the force acting on the strain body.
The force sensor according to claim 1. A space is formed between the first connection structure and the second connection structure,
When viewed in a third direction perpendicular to each of the first direction and the second direction, the space portion bulges out on a side opposite to the second connection structure portion in the second direction. 1. A buffer structure is formed.
The force sensor according to claim 12. When viewed in the third direction, the space portion bulges toward the second sensor body in the first direction and bulges out in the second direction on a side opposite to the second connection structure portion. the first buffer structure is formed so as to
The force sensor according to claim 13. The second connection structure includes a second buffer structure that buffers the force acting on the strain body.
The force sensor according to claim 1. A space is formed between the first connection structure and the second connection structure,
When viewed in a third direction perpendicular to each of the first direction and the second direction, the space portion bulges on a side opposite to the first connection structure portion in the second direction. the second buffer structure is formed so as to
The force sensor according to claim 15. A spring constant of the third connection structure is larger than a spring constant of the first connection structure and a spring constant of the second connection structure.
The force sensor according to claim 1 or 2.

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