JP7438569B2 - force sensor - Google Patents

Description

The present invention relates to a force sensor.

2. Description of the Related Art Force sensors have been known that output a force acting in a predetermined axial direction and a moment (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. For this reason, a force sensor with high performance and high sensitivity is required, but there is also a need to reduce the cost of the force sensor. However, since the force sensor has a complicated structure, it has been difficult to reduce the price.

Patent No. 6257017

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

The present invention
a force receiving body subjected to the action of a force or moment to be detected;
a support body disposed on one side of the force receiving body in a first direction and supporting the force receiving body;
a strain-generating body that connects the force-receiving body and the support body and is elastically deformed by the action of a force or moment received by the force-receiving body;
a detection element that detects displacement caused by elastic deformation of the strain body;
a detection circuit that outputs an electric signal indicating the force or moment acting on the strain body based on the detection result of the detection element,
The strain-generating body includes an elastically deformable body extending in the first direction from a force-receiving body-side end connected to the force-receiving body to a support-side end connected to the support body; a displacement body protruding in a second direction orthogonal to the first direction;
The detection element includes a fixed electrode substrate provided on the support body, and a displacement electrode substrate provided on the displacement body facing the fixed electrode substrate, a force sensor;
I will provide a.

In addition, in the force sensor mentioned above,
A direction perpendicular to the first direction and the second direction is a third direction,
The dimension of the elastically deformable body in the third direction is larger than the dimension of the elastically deformable body in the second direction.
You can do it like this.

Furthermore, in the force sensor described above,
The strain body includes two displacement bodies protruding in the second direction on both sides of the elastic deformation body,
The detection element includes two of the fixed electrode substrates and two of the displacement electrode substrates facing the corresponding fixed electrode substrates,
Each of the displacement bodies may be provided with the displacement electrode substrate.

Furthermore, in the force sensor described above,
The force-receiving body and the support body are connected by the four strain-generating bodies,
The four strain bodies include a first strain body, a second strain body, a third strain body, and a fourth strain body,
The first direction is the Z-axis direction in the XYZ three-dimensional coordinate system,
When viewed in the Z-axis direction, the first strain body is arranged on the negative side in the Y-axis direction with respect to the center of the force-receiving body, and on the positive side in the X-axis direction with respect to the center of the force-receiving body. The second strain-generating body is arranged, the third strain-generating body is arranged on the positive side in the Y-axis direction with respect to the center of the force-receiving body, and the third strain-generating body is arranged on the negative side in the X-axis direction with respect to the center of the force-receiving body. the fourth strain body is arranged,
The second direction of the first flexural body and the third flexural body is the X-axis direction,
The second direction of the second flexure element and the fourth flexure element is the Y-axis direction;
You can do it like this.

Furthermore, in the force sensor described above,
The displacement body projects from the elastic deformation body in the second direction on one side of the elastic deformation body and does not protrude on the other side.
You can do it like this.

Furthermore, in the force sensor described above,
The displacement body is provided with a plurality of the displacement electrode substrates,
the support body is provided with the fixed electrode substrates facing each of the displacement electrode substrates;
You can do it like this.

Furthermore, in the force sensor described above,
The force-receiving body and the support body are connected by the four strain-generating bodies,
The four strain bodies include a first strain body, a second strain body, a third strain body, and a fourth strain body,
The first direction is the Z-axis direction in the XYZ three-dimensional coordinate system,
When viewed in the Z-axis direction, the first strain body is arranged on the negative side in the Y-axis direction with respect to the center of the force-receiving body, and on the positive side in the X-axis direction with respect to the center of the force-receiving body. The second strain-generating body is arranged, the third strain-generating body is arranged on the positive side in the Y-axis direction with respect to the center of the force-receiving body, and the third strain-generating body is arranged on the negative side in the X-axis direction with respect to the center of the force-receiving body. the fourth strain body is arranged,
The second direction of the first flexural body and the third flexural body is the X-axis direction,
The second direction of the second flexure body and the fourth flexure body is the Y-axis direction,
The displacement body of the first strain body and the displacement body of the second strain body face each other,
The displacement body of the third strain body and the displacement body of the fourth strain body face each other,
You can do it like this.

Furthermore, in the force sensor described above,
The force receiving body includes a first force receiving body opening that separates the force receiving body side end portion of the first strain body and the force receiving body side end portion of the second strain body, and the third strain body. a second force receiving body opening that separates the force receiving body side end of the fourth strain body from the force receiving body side end of the fourth strain body;
You can do it like this.

Furthermore, in the force sensor described above,
The support body includes a first support opening that separates the support side end portion of the second strain body and the support body side end portion of the third strain body, and a first support opening that separates the support side end portion of the fourth strain body. a second support opening that separates the end portion and the support side end portion of the first flexure body;
You can do it like this.

Furthermore, in the force sensor described above,
The force-receiving body includes a force-receiving body main body portion, and a force-receiving body thin portion that is thinner than the force-receiving body main body portion and connected to the force-receiving body side end portion of the flexure body.
You can do it like this.

Furthermore, in the force sensor described above,
The support body includes a support body portion, and a support thin portion that is thinner than the support body portion and connected to the support side end portion of the flexure body.
You can do it like this.

Furthermore, in the force sensor described above,
The force-receiving body and the support body are connected by a plurality of the strain-generating bodies,
The detection element is configured with an even number of the displacement electrode substrates, which is smaller than the number of the displacement bodies,
Each of some of the displacement bodies is provided with the displacement electrode substrate, and other displacement bodies are not provided with the displacement electrode substrate,
When a moment around the axis along the first direction acts on the force sensor, some of the displacement electrode substrates move away from the opposing fixed electrode substrate, and the remaining displacement electrode substrates move away from the opposing fixed electrode substrate. approach the fixed electrode substrate,
You can do it like this.

Furthermore, in the force sensor described above,
The strain body includes two displacement bodies protruding in the second direction on both sides of the elastic deformation body.
You can do it like this.

Furthermore, in the force sensor described above,
The displacement body projects from the elastic deformation body in the second direction on one side of the elastic deformation body and does not protrude on the other side.
You can do it like this.

According to the present invention, the structure can be simplified.

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 sectional view showing the force sensor according to the first embodiment. FIG. 3 is a plan view showing the sensory sensor shown in FIG. 2. FIG. FIG. 4 is a front view of the strain body shown in FIG. 2. FIG. FIG. 5 is a plan view of the strain-generating body shown in FIG. 3. FIG. 6 is a front view schematically showing a deformed state of the strain body when the force receiving body receives a force on the positive side in the X-axis direction. FIG. 7 is a table showing changes in the capacitance value of each capacitive element in the force sensor shown in FIG. FIG. 8 is a sectional view showing a force sensor according to the second embodiment. FIG. 9 is a plan view showing the force sensor shown in FIG. 8. FIG. 10 is a table showing changes in capacitance values of each capacitive element in the force sensor shown in FIG. FIG. 11 is a sectional view showing a force sensor according to the third embodiment. FIG. 12 is a plan view showing the force sensor shown in FIG. 11. FIG. 13 is a table showing changes in capacitance values of each capacitive element in the force sensor shown in FIG. 12. FIG. 14 is a perspective view showing a force sensor according to the fourth embodiment. FIG. 15 is a sectional view showing a force sensor according to the fifth embodiment. FIG. 16 is a plan view showing the force sensor shown in FIG. 15. FIG. 17 is a front view schematically showing a deformed state of the strain body when the force receiving body receives a force on the positive side in the Z-axis direction. FIG. 18 is a front view schematically showing a deformed state of the strain body when the force receiving body receives a force on the negative side in the Z-axis direction. FIG. 19 is a table showing changes in capacitance values of each capacitive element in the force sensor shown in FIG. 16. FIG. 20 is a table showing the main axis sensitivity and other axis sensitivity based on the change in capacitance value shown in FIG. 19.

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.

In addition, terms used in this specification to specify shapes, geometric conditions, physical properties, and their degrees, such as "parallel," "orthogonal," "equal," etc., dimensions, and values of physical properties etc., shall be interpreted to include the extent to which similar functions can be expected, without being bound by strict meanings.

(First embodiment)
First, a force sensor according to a first embodiment of the present invention will be described using FIGS. 1 to 7.

First, the robot 1 to which the force sensor 10 is attached will be explained with reference to FIG. Examples of the robot 1 include various robots such as industrial robots, collaborative robots, life support robots, medical robots, and service robots. In the following, an explanation will be given using an industrial robot as an example. FIG. 1 is a perspective view showing an example of a robot 1 to which a force sensor according to the present embodiment is applied.

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, the tool 3 is attached to the tip of the robot arm 4. 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 a gripper and a tool changer (none of which are 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 according to this embodiment will be described below with reference to FIGS. 2 to 5. FIG. 2 is a sectional view showing the force sensor 10 according to the first embodiment. FIG. 3 is a plan view showing the force sensor 10 of FIG. 2. FIG. FIG. 4 is a front view showing the first strain body 40A of FIG. 2. FIG. 5 is a plan view of each strain body 40A to 40D of the force sensor 10 shown in FIG. 3. As shown in FIG.

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 support body 30 is placed on the bottom side. The description will be made with the sense sensor 10 arranged. For this reason, the force sensor 10 in this embodiment is not limited to being used in a posture with the Z-axis direction as the vertical direction. Further, it is optional whether the force receiving body 20 or the support body 30 is disposed 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 (torque) 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 support body 30, strain bodies 40A to 40D, a detection element 60, a detection circuit 70, an exterior body 80, It is equipped with Each component will be explained in more detail below.

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 support body 30. In the example of FIG. 1 described above, the force receiving body 20 is fixed to the tool 3 with a bolt or the like, and receives force or moment from the tool 3.

The force receiving body 20 is formed along the X-axis direction and the Y-axis direction. As shown in FIG. 3, the force receiving body 20 may include a force receiving body center opening 20a. In this case, the planar shape of the force receiving body 20 may be approximately a circular ring shape. In FIG. 2, the force receiving body center opening 20a is omitted. Further, the force receiving body 20 may be formed in a flat plate shape.

As shown in FIG. 2, the support body 30 supports the force receiving body 20. The support body 30 is arranged on the negative side of the force receiving body 20 in the Z-axis direction. The force receiving body 20 and the support body 30 are arranged at mutually different positions in the Z-axis direction, and the support body 30 is separated from the force receiving body 20. In the example of FIG. 1, the support body 30 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 support body 30 is formed along the X-axis direction and the Y-axis direction. As shown in FIG. 3, the support 30 may include a support center opening 30a. In this case, the planar shape of the support body 30 may be approximately a circular ring shape. In plan view, the support body center opening 30a may overlap the force receiving body center opening 20a. In FIG. 2, the support center opening 30a is omitted. Further, the support body 30 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 support body 30 may be a planar shape other than the circular ring shape. In this case, one of the planar shape of the force receiving body 20 and the planar shape of the support body 30 may be circular, and the other may be a shape other than circular. For example, the planar shape of the force receiving body 20 may be a circular shape that does not include the force receiving body center opening 20a. Alternatively, the planar shape of the force receiving body 20 may be rectangular (for example, rectangular or square). The planar shape of the support body 30 is also similar.

As shown in FIGS. 2 and 3, the strain-generating bodies 40A to 40D connect the force receiving body 20 and the support body 30. As shown in FIGS. The strain-generating bodies 40A to 40D are arranged between the force-receiving body 20 and the support body 30, and are connected to the force-receiving body 20 and to the support body 30. The force-receiving body 20 is supported by the support body 30 via the strain-generating bodies 40A to 40D.

In this embodiment, the force receiving body 20 and the support body 30 are connected by four strain bodies 40A to 40D. The four strain bodies 40A to 40D include a first strain body 40A, a second strain body 40B, a third strain body 40C, and a fourth strain body 40D. As shown in FIG. 3, the first strain body 40A 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. Similarly, when viewed in the Z-axis direction, the second strain body 40B is arranged on the positive side in the X-axis direction with respect to the center O of the force-receiving body 20, and on the positive side in the Y-axis direction with respect to the center O of the force-receiving body 20. A third strain body 40C is arranged on the positive side. A fourth strain-generating body 40D is arranged on the negative side in the X-axis direction with respect to the center O of the force-receiving body 20. In other words, the center O of the force receiving body 20 is arranged between the first strain body 40A and the third strain body 40C, and between the second strain body 40B and the fourth strain body 40D, A center O of the force receiving body 20 is located. Note that the number of strain-generating bodies connecting the force-receiving body 20 and the support body 30 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 support body 30 may be connected by only one strain body, and in this case, if the detection element 60 is composed of two capacitive elements as shown in FIG. It is possible to detect the two-axis components of . Details will be described later. Alternatively, the detection element 60 may be configured with only one capacitive element to detect a uniaxial component of force.

The strain bodies 40A to 40D will be explained in more detail.

The strain-generating bodies 40A to 40D 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 40A to 40D described above, the first strain body 40A whose second direction is the X-axis direction will be described as an example.

As shown in FIGS. 2 and 4, the first strain body 40A includes an elastically deformable body 41 and a displacement beam 42. As shown in FIGS.

The elastic deformable body 41 extends in the Z-axis direction. The elastic deformable body 41 includes a force receiving body side end portion 43 connected to the force receiving body 20 and a support body side end portion 44 connected to the support body 30. The elastic deformable body 41 extends linearly along the Z-axis direction from the force-receiving body side end 43 to the support body side end 44.

The elastically deformable body 41 according to this embodiment can be elastically deformed by the action of a force in the second direction, and can also be elastically deformed by the action of a force in the third direction. The second direction is a direction perpendicular to the first direction. The third direction is a direction perpendicular to the first direction and perpendicular to the second direction. The second direction of the first strain body 40A is the X-axis direction, and the third direction is the Y-axis direction.

The dimension of the elastically deformable body 41 according to this embodiment in the Y-axis direction is equal to the dimension of the elastically deformable body 41 in the X-axis direction. In this case, the spring constant of the elastic deformable body 41 with respect to the action of a force in the Y-axis direction is equal to the spring constant with respect to the action of a force in the X-axis direction. The cross-sectional shape of the elastically deformable body 41 along the XY plane may be approximately rectangular such as a square, or approximately circular, and is arbitrary.

The displacement beam 42 is an example of a displacement body. The displacement beam 42 protrudes from the elastically deformable body 41 in the X-axis direction. The first strain body 40A according to this embodiment includes two displacement beams 42 that protrude in the X-axis direction on both sides of the elastically deformable body 41. One displacement beam 42 protrudes from the elastically deformable body 41 toward the negative side in the X-axis direction, and the other displacement beam 42 protrudes from the elastically deformable body 41 toward the positive side in the X-axis direction. The displacement beam 42 may extend from the elastically deformable body 41 in the X-axis direction. The displacement beam 42 may be configured as a cantilever supported by the elastically deformable body 41. The displacement beam 42 may be formed linearly along the X-axis direction. The displacement beam 42 is apart from the force receiving body 20 and also away from the support body 30 in the Z-axis direction. The displacement beam 42 may be arranged at a position closer to the support body 30 than an intermediate position between the force receiving body side end portion 43 and the support body side end portion 44. The displacement beam 42 faces the support 30 .

The second strain body 40B has the Y-axis direction as its second direction and the X-axis direction as its third direction. The third strain body 40C has the X-axis direction as its second direction and the Y-axis direction as its third direction. The fourth strain body 40D has the Y-axis direction as its second direction and the X-axis direction as its third direction. Since the second flexural body 40B, the third flexural body 40C, and the fourth flexural body 40D are configured similarly to the first flexural body 40A, the second flexural body 40B, the third flexural body 40C, and A detailed explanation of the individual configurations of the fourth strain body 40D will be omitted.

As shown in FIG. 3, the displacement beams 42 of the strain generating bodies 40A to 40D according to this embodiment are arranged in an annular shape. As described above, the force receiving body 20 and the support body 30 are formed in a circular ring shape when viewed in the Z-axis direction, and the displacement beams 42 of the four strain bodies 40A to 40D form a rectangular ring shape. It is arranged like this. The displacement beams 42 of each of the strain-generating bodies 40A to 40D are formed linearly along the respective second directions when viewed in the Z-axis direction. Note that the arrangement of the four strain-generating bodies 40A to 40D is not limited to an annular arrangement, and each may be arranged irregularly at any position.

The first strain body 40A configured in this manner may be formed by machining from a plate material made of a metal material such as an aluminum alloy or an iron alloy, or may be formed by casting. When formed by machining, the elastic deformable body 41 and the displacement beam 42 are formed into a plate shape such that the Y-axis direction (third direction) is the thickness direction, and are integrally formed from a continuous plate material. . Thereby, the first strain body 40A can be easily manufactured. The first strain body 40A formed in this manner may be fixed to the force receiving body 20 and the support body 30 with bolts, an adhesive, or the like. The same applies to the second strain body 40B, the third strain body 40C, and the fourth strain body 40D. Alternatively, the force-receiving body 20, the support body 30, and the strain-generating bodies 40A to 40D may be integrally formed from a continuous block material by machining (for example, cutting) or by casting. Good too.

The detection element 60 will be explained.

The detection element 60 is configured to detect the displacement caused by the elastic deformation of the first strain body 40A described above. Detection element 60 according to this embodiment includes a capacitive element that detects capacitance. As shown in FIG. 4, the capacitive element includes a fixed electrode substrate provided on the support body 30 and a displacement electrode substrate provided on the displacement beam 42. The displacement electrode substrate faces the fixed electrode substrate. In this embodiment, the detection element 60 includes a first capacitive element C1 to an eighth capacitive element C8. The detection element 60 includes a displacement electrode substrate provided on each displacement beam 42 and a corresponding fixed electrode substrate.

In the example shown in FIG. 4, the detection element 60 includes two fixed electrode substrates Ef1 and Ef2 and two displacement electrode substrates Ed1 and Ed2 as electrodes for the first strain body 40A. Displacement electrode substrates Ed1 and Ed2 are arranged on each displacement beam 42 of the first strain body 40A. One displacement electrode substrate Ed1, Ed2 is arranged on one displacement beam 42. Each fixed electrode substrate Ef1, Ef2 is arranged on the support body 30 at a position facing the corresponding displacement electrode substrate Ed1, Ed2.

As shown in FIG. 4, the two fixed electrode substrates Ef1 and Ef2 include a first fixed electrode substrate Ef1 and a second fixed electrode substrate Ef2. The first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 are arranged at mutually different positions in the X-axis direction. In the present embodiment, the first fixed electrode substrate Ef1 is arranged on the negative side of the elastically deformable body 41 in the X-axis direction, and the second fixed electrode substrate Ef2 is arranged on the positive side of the X-axis direction with respect to the elastically deformable body 41. It is located.

In this embodiment, the fixed electrode substrates Ef1 and Ef2 are arranged on the surface of the support body 30 on the side of the force receiving body 20. The fixed electrode substrates Ef1 and Ef2 may be bonded to the support body 30 with an adhesive, or may be fixed with bolts or the like. The fixed electrode substrates Ef1 and Ef2 include a fixed electrode Ef facing the corresponding displacement electrode substrate Ed1 and Ed2, and an insulator IBf interposed between the fixed electrode Ef and the support 30.

As shown in FIG. 4, the two displacement electrode substrates Ed1 and Ed2 include a first displacement electrode substrate Ed1 and a second displacement electrode substrate Ed2. The first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 are arranged at different positions in the X-axis direction. In the present embodiment, the first displacement electrode substrate Ed1 is disposed on the negative side of the elastic deformable body 41 in the X-axis direction, and is disposed on the displacement beam 42 that protrudes from the elastic deformable body 41 on the negative side of the X-axis direction. There is. The second displacement electrode substrate Ed2 is disposed on the positive side of the X-axis direction relative to the elastic deformation body 41, and is disposed on a displacement beam 42 that protrudes from the elastic deformation body 41 on the positive side of the X-axis direction. The first displacement electrode substrate Ed1 may be arranged at the end of the displacement beam 42 on the negative side in the X-axis direction. The second displacement electrode substrate Ed2 may be arranged at the end of the displacement beam 42 on the positive side in the X-axis direction.

In this embodiment, the displacement electrode substrates Ed1 and Ed2 are provided on the surface of the displacement beam 42 on the support body 30 side. The displacement electrode substrates Ed1 and Ed2 may be joined to the displacement beam 42 with an adhesive, or may be fixed with bolts or the like. The displacement electrode substrates Ed1 and Ed2 include a displacement electrode Ed facing the corresponding fixed electrode substrate Ef1 and Ef2, and an insulator IBd interposed between the displacement electrode Ed and the displacement beam 42.

The first fixed electrode substrate Ef1 faces the first displacement electrode substrate Ed1. The first capacitive element C1 is configured by the first fixed electrode substrate Ef1 and the first displacement electrode substrate Ed1. The second fixed electrode substrate Ef2 faces the second displacement electrode substrate Ed2. The second capacitive element C2 is configured by the second fixed electrode substrate Ef2 and the second displacement electrode substrate Ed2. The first capacitive element C1 and the second capacitive element C2 are configured as a detection element 60 for the first strain body 40A.

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 first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 are arranged at the same position in the Y-axis direction, and the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 are also arranged at the same position in the Y-axis direction. It is located in

In this embodiment, the planar shape of the fixed electrode substrates Ef1 and Ef2 is rectangular. The planar shape of the displacement electrode substrates Ed1 and Ed2 is also rectangular. However, the planar shapes of the fixed electrode substrates Ef1, Ef2 and the planar shapes of the displacement electrode substrates Ed1, Ed2 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 first fixed electrode substrate Ef1 may be larger than the first displacement electrode substrate Ed1. For example, the planar shape of the first fixed electrode substrate Ef1 may be larger than the planar shape of the first displacement electrode substrate Ed1. Even if the first displacement electrode substrate Ed1 is displaced in the X-axis direction, Y-axis direction, or Z-axis direction, the first displacement electrode substrate Ed1 as a whole remains in the first fixed position when viewed in the Z-axis direction. It may overlap the electrode substrate Ef1. In other words, even if the first displacement electrode substrate Ed1 is displaced in the X-axis direction, Y-axis direction, or Z-axis direction, the size and fixation of the displacement electrode Ed is such that the displacement electrode Ed and the fixed electrode Ef overlap. The size of the electrode Ef may be set. In this way, even if the first displacement electrode substrate Ed1 is displaced, it is possible to prevent the facing area of the displacement electrode Ed and the fixed electrode Ef from changing, and to It is possible to prevent changes in area from having an effect. Therefore, the capacitance value can be changed according to a change in the distance between the displacement electrode Ed and the fixed electrode Ef. Here, the opposing area refers to the area where the displacement electrode Ed and the fixed electrode Ef overlap when viewed in the Z-axis direction. When the displacement beam 42 tilts, the displacement electrode Ed, which is smaller than the fixed electrode Ef, may tilt and the opposing area may vary, but in this case, the tilt angle of the displacement electrode Ed is small. As a result, the change in capacitance value is dominated by the distance between the displacement electrode Ed and the fixed electrode Ef. 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 fixed electrode Ef. Note that in FIG. 6 and other figures described later, the inclination of the displacement beam 42 is exaggerated to make the drawings clearer. Further, the planar shape of the first fixed electrode substrate Ef1 is not limited to being larger than the planar shape of the first displacement electrode substrate Ed1, and the planar shape of the first displacement electrode substrate Ed1 is different from that of the first fixed electrode substrate Ed1. It may be larger than the planar shape of the substrate Ef1.

Similarly, when viewed in the Z-axis direction, the planar shape of the second fixed electrode substrate Ef2 may also be larger than the planar shape of the second displacement electrode substrate Ed2. Note that the planar shape of the second displacement electrode substrate Ed2 may be larger than the planar shape of the second fixed electrode substrate Ef2.

The planar shape of the fixed electrode Ef of the fixed electrode substrates Ef1 and Ef2 and the planar shape of the insulator IBf may be the same size. However, the present invention is not limited to this, and the planar shape of the fixed electrode Ef and the planar shape of the insulator IBf may have different sizes from each other. The planar shape of the displacement electrode Ed of the displacement electrode substrates Ed1 and Ed2 and the planar shape of the insulator IBd are also similar.

The first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 may be formed separately and separated from each other, as shown in FIG. 4. However, the present invention is not limited to this, and the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 may be integrated into one common fixed electrode substrate. In this case, the insulator IBf and the fixed electrode Ef may be each integrated. Alternatively, even if the fixed electrodes Ef are configured to be separated from each other, the insulator IBf may be integrated.

The configuration of the first strain body 40A and the corresponding detection element 60 described above can be similarly applied to the second strain body 40B, the third strain body 40C, and the fourth strain body 40D.

That is, as shown in FIG. 5, the detection element 60 has two fixed electrode substrates Ef3 and Ef4 provided on the support body 30 and two fixed electrode substrates Ef4 provided on the displacement beam 42 as electrodes for the second strain body 40B. It further includes two displacement electrode substrates Ed3 and Ed4. The two fixed electrode substrates Ef3 and Ef4 include a third fixed electrode substrate Ef3 and a fourth fixed electrode substrate Ef4. The two displacement electrode substrates Ed3 and Ed4 include a third displacement electrode substrate Ed3 and a fourth displacement electrode substrate Ed4. The third fixed electrode substrate Ef3 faces the third displacement electrode substrate Ed3, and the fourth fixed electrode substrate Ef4 faces the fourth displacement electrode substrate Ed4. The third fixed electrode substrate Ef3 and the third displacement electrode substrate Ed3 constitute a third capacitive element C3, and the fourth fixed electrode substrate Ef4 and the fourth displacement electrode substrate Ed4 constitute a fourth capacitive element C4.

The third displacement electrode substrate Ed3 and the third fixed electrode substrate Ef3 are arranged on the negative side of the elastic deformable body 41 in the Y-axis direction. The third displacement electrode substrate Ed3 is arranged on a displacement beam 42 that protrudes from the elastic deformation body 41 toward the negative side in the Y-axis direction. The fourth displacement electrode substrate Ed4 and the fourth fixed electrode substrate Ef4 are arranged on the positive side of the elastic deformable body 41 in the Y-axis direction. The fourth displacement electrode substrate Ed4 is arranged on a displacement beam 42 that projects from the elastic deformable body 41 to the positive side in the Y-axis direction. The third capacitive element C3 and the fourth capacitive element C4 are arranged at the same position in the X-axis direction. The fixed electrode substrates Ef3 and Ef4 have the same configuration as the fixed electrode substrates Ef1 and Ef2 described above. The displacement electrode substrates Ed3 and Ed4 have the same configuration as the displacement electrode substrates Ed1 and Ed2 described above.

The detection element 60 also includes two fixed electrode substrates Ef5 and Ef6 provided on the support body 30 and two displacement electrode substrates Ed5 and Ed6 provided on the displacement beam 42 as electrodes for the third strain body 40C. It further includes. The two fixed electrode substrates Ef5 and Ef6 include a fifth fixed electrode substrate Ef5 and a sixth fixed electrode substrate Ef6. The two displacement electrode substrates Ed5 and Ed6 include a fifth displacement electrode substrate Ed5 and a sixth displacement electrode substrate Ed6. The fifth fixed electrode substrate Ef5 faces the fifth displacement electrode substrate Ed5, and the sixth fixed electrode substrate Ef6 faces the sixth displacement electrode substrate Ed6. The fifth fixed electrode substrate Ef5 and the fifth displacement electrode substrate Ed5 constitute a fifth capacitive element C5, and the sixth fixed electrode substrate Ef6 and the sixth displacement electrode substrate Ed6 constitute a sixth capacitive element C6.

The fifth displacement electrode substrate Ed5 and the fifth fixed electrode substrate Ef5 are arranged on the positive side of the elastic deformable body 41 in the X-axis direction. The fifth displacement electrode substrate Ed5 is arranged on a displacement beam 42 that protrudes from the elastic deformable body 41 toward the positive side in the X-axis direction. The sixth displacement electrode substrate Ed6 and the sixth fixed electrode substrate Ef6 are arranged on the negative side of the elastically deformable body 41 in the X-axis direction. The sixth displacement electrode substrate Ed6 is arranged on a displacement beam 42 that protrudes from the elastically deformable body 41 toward the negative side in the X-axis direction. The fifth capacitive element C5 and the sixth capacitive element C6 are arranged at the same position in the Y-axis direction. The fixed electrode substrates Ef5 and Ef6 have the same configuration as the fixed electrode substrates Ef1 and Ef2 described above. The displacement electrode substrates Ed5 and Ed6 have the same configuration as the displacement electrode substrates Ed1 and Ed2 described above.

The detection element 60 also includes two fixed electrode substrates Ef7 and Ef8 provided on the support body 30 and two displacement electrode substrates Ed7 and Ed8 provided on the displacement beam 42 as electrodes for the fourth strain body 40D. It further includes. The two fixed electrode substrates Ef7 and Ef8 include a seventh fixed electrode substrate Ef7 and an eighth fixed electrode substrate Ef8. The two displacement electrode substrates Ed7 and Ed8 include a seventh displacement electrode substrate Ed7 and an eighth displacement electrode substrate Ed8. The seventh fixed electrode substrate Ef7 faces the seventh displacement electrode substrate Ed7, and the eighth fixed electrode substrate Ef8 faces the eighth displacement electrode substrate Ed8. The seventh fixed electrode substrate Ef7 and the seventh displacement electrode substrate Ed7 constitute a seventh capacitive element C7, and the eighth fixed electrode substrate Ef8 and the eighth displacement electrode substrate Ed8 constitute an eighth capacitive element C8.

The seventh displacement electrode substrate Ed7 and the seventh fixed electrode substrate Ef7 are arranged on the positive side of the elastic deformable body 41 in the Y-axis direction. The seventh displacement electrode substrate Ed7 is arranged on a displacement beam 42 that projects from the elastic deformable body 41 to the positive side in the Y-axis direction. The eighth displacement electrode substrate Ed8 and the eighth fixed electrode substrate Ef8 are arranged on the negative side of the elastic deformable body 41 in the Y-axis direction. The eighth displacement electrode substrate Ed8 is disposed on a displacement beam 42 that protrudes from the elastic deformable body 41 toward the negative side in the Y-axis direction. The seventh capacitive element C7 and the eighth capacitive element C8 are arranged at the same position in the X-axis direction. The fixed electrode substrates Ef7 and Ef8 have the same configuration as the fixed electrode substrates Ef1 and Ef2 described above. The displacement electrode substrates Ed7 and Ed8 have the same configuration as the displacement electrode substrates Ed1 and Ed2 described above.

Each of the fixed electrode substrates Ef1 to Ef8 described above may be composed of a ceramic substrate, a glass epoxy substrate, or an FPC substrate (flexible printed circuit board) on which electrode materials are laminated. The FPC board is a flexible printed circuit board formed in the form of a thin film, but it may be entirely bonded to the support body 30. Each of the fixed electrode substrates Ef1 to Ef8 may be bonded to the support body 30 with an adhesive. The same applies to each of the displacement electrode substrates Ed1 to Ed8. Each of the displacement electrode substrates Ed1 to Ed8 may be bonded to the displacement beam 42 with an adhesive.

As shown in FIG. 2, the detection circuit 70 outputs an electric signal indicating the force or moment acting on the strain bodies 40A to 40D based on the detection result of the detection element 60. This detection circuit 70 may have an arithmetic function configured by a microprocessor, for example. Further, the detection circuit 70 may have an A/D conversion function that converts the analog signal received from the detection element 60 described above into a digital signal, a signal amplification function, and various correction functions. The detection circuit 70 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.

As shown in FIGS. 2 and 3, the exterior body 80 is configured to cover the four strain-generating bodies 40A to 40D 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 40A to 40D are housed in an exterior body 80. In this embodiment, the planar cross-sectional shape (shape in a cross section along the XY plane) of the exterior body 80 is a circular frame shape.

As shown in FIG. 2, the exterior body 80 includes a force receiving body side cover 81 attached to the force receiving body 20, a support body side cover 82 attached to the support body 30, a force receiving body side cover 81 and a support body side cover 82. and a buffer member 83 interposed between. The force-receiving body side cover 81 may be attached to the force-receiving body 20 in a sealed manner, or may be integrally formed. The support side cover 82 may be attached to the support 30 in a sealed manner, or may be integrally formed. The buffer member 83 may be composed of, for example, a dustproof and waterproof rubber packing. This buffer member 83 can prevent foreign matter such as dust from entering the inside through the gap between the force-receiving body side cover 81 and the support body side cover 82. Further, the force receiving body 20 is movable relative to the support body 30.

Next, a method for detecting force or moment in the force sensor according to the present embodiment having such a configuration will be described.

When the force receiving body 20 is subjected to a force or moment, the force or moment is transmitted to the first strain body 40A to the fourth strain body 40D. More specifically, the force or moment is transmitted to the elastically deformable body 41, causing the elastically deformable body 41 to be elastically deformed. As a result, the displacement beam 42 is tilted and displaced. Therefore, the distance between each fixed electrode substrate Ef1 to Ef8 of the detection element 60 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 60 as a displacement occurring in the strain-generating bodies 40A to 40D. In this case, the capacitance values of each of the capacitive elements C1 to C8 may change differently. Therefore, the detection circuit 70 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 60. be able to.

Here, as an example, FIG. 6 shows changes in the capacitance values of the first capacitive element C1 and the second capacitive element C2 when a force Fx in the X-axis direction is applied to the single first strain body 40A. I will explain using FIG. 6 is a front view schematically showing a deformed state of the first strain body 40A when the force receiving body 20 receives a force Fx on the positive side in the X-axis direction.

When force Fx is applied to the first strain body 40A in the positive direction of the X-axis, the elastically deformable body 41 of the first strain body 40A is elastically deformed, as shown in FIG. In this case, the force-receiving body side end 43 of the elastically deformable body 41 is displaced toward the positive side in the X-axis direction, and the elastically deformable body 41 is elastically deformed so as to bend toward the positive side in the X-axis direction. In FIG. 6, in order to simplify the drawing, the elastic deformable body 41 is shown in a tilted state. The displacement beam 42 tilts and is displaced. As a result, the first displacement electrode substrate Ed1 rises and moves away from the first fixed electrode substrate Ef1. 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, and the capacitance value of the first capacitive element C1 decreases. On the other hand, the second displacement electrode substrate Ed2 descends and approaches the second fixed electrode substrate Ef2. The inter-electrode distance between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 decreases, and the capacitance value of the second capacitive element C2 increases.

The force Fx acting on the first strain body 40A 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 Fx 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 C1 and C2.
[Formula 1]
Fx=-C1+C2

Also when the moment My around the Y axis acts on the first strain body 40A alone, the elastically deformable body 41 is elastically deformed as in FIG. 6 . The capacitance value of the first capacitive element C1 decreases, and the capacitance value of the second capacitive element C2 increases. Therefore, the moment My is calculated in the same manner as Equation 1 described above.
[Formula 2]
My=-C1+C2

When the force Fy in the Y-axis direction acts on the first strain body 40A alone, it can be considered that there is no change in the capacitance value of each capacitive element C1, C2. This is because, as described above, the first capacitive element C1 and the second capacitive element C2 are arranged at the same position in the Y-axis direction. In this case, the amount of change in capacitance value in the positive side portion of each capacitive element C1, C2 in the Y-axis direction and the amount of change in capacitance value in the negative side portion are offset. Similarly, when the moment Mx around the X axis acts on the first strain body 40A alone, it can be assumed that there is no change in the capacitance value of each capacitive element C1, C2.

When the force Fz in the Z-axis direction acts on the first strain body 40A alone, it can be considered that there is no change in the capacitance value of each capacitive element C1, C2. As described above, since the elastically deformable body 41 extends in the Z-axis direction from the force-receiving body side end 43 to the support body side end 44, the elastically deformable body 41 has increased rigidity against forces in the Z-axis direction, and is substantially acts as a rigid body. The elastically deformable body 41 does not elastically deform in the Z-axis direction, and it can be considered that the elastically deformable body 41 does not expand or contract in the Z-axis direction.

In this way, the force sensor 10 in which the force receiving body 20 and the support body 30 are connected only by the first strain body 40A can detect the force Fx and the moment My. This force sensor 10 may be used in an environment where only one of force Fx and moment My acts.

Next, the static state of each capacitive element C1 to C8 when a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a moment Mz around the Z-axis are applied to the force receiving body 20 of the force sensor 10 shown in FIG. The change in capacitance value will be explained using FIG. 7. FIG. 7 is a table showing changes in capacitance values of each capacitive element C1 to C8.

(When +Fx works)
First, a case where force Fx acts on the force receiving body 20 on the positive side in the X-axis direction will be described.

In this case, the first strain body 40A is elastically deformed as shown in FIG. 6, and the capacitance value of the first capacitive element C1 decreases while the capacitance value of the second capacitive element C2 increases. This is shown as "- (minus)" in C1 of the Fx row in the table shown in FIG. 7, and as "+ (plus)" in C2.

The second strain body 40B rotates around the Y-axis (clockwise toward the positive side in the Y-axis direction). However, the third capacitive element C3 and the fourth capacitive element C4 are arranged at the same position in the X-axis direction. Therefore, similarly to the case where the force Fy in the Y-axis direction acts on the first strain body 40A, no change in the capacitance value appears for the third capacitive element C3 as a whole and the fourth capacitive element C4 as a whole. . This is shown as "0 (zero)" in C3 and C4 of the Fx row in the table shown in FIG.

The third strain body 40C is elastically deformed similarly to the first strain body 40A shown in FIG. Therefore, the capacitance value of the fifth capacitive element C5 increases and the capacitance value of the sixth capacitive element C6 decreases. This is shown as "+" in C5 of the Fx row in the table shown in FIG. 7, and as "-" in C6.

The fourth strain body 40D rotates around the Y axis similarly to the second strain body 40B. However, as described above, the seventh capacitive element C7 and the eighth capacitive element C8 are arranged at the same position in the X-axis direction. Therefore, no change in capacitance value appears for the seventh capacitive element C7 as a whole and the eighth capacitive element C8 as a whole. This is shown as "0 (zero)" in C7 and C8 of the Fx row in the table shown in FIG.

(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. 7 are determined according to changes in the capacitance value, as described above.

In this case, the first strain body 40A rotates around the X-axis (counterclockwise toward the positive side in the X-axis direction). However, as described above, the first capacitive element C1 and the second capacitive element C2 are arranged at the same position in the Y-axis direction. Therefore, no change in capacitance value appears for the first capacitive element C1 as a whole and the second capacitive element C2 as a whole.

The second strain body 40B is elastically deformed in the same way as the first strain body 40A shown in FIG. increase

The third flexure element 40C rotates around the X-axis similarly to the first flexure element 40A. However, the fifth capacitive element C5 and the sixth capacitive element C6 are arranged at the same position in the Y-axis direction. Therefore, no change in capacitance value appears for the fifth capacitive element C5 as a whole and the sixth capacitive element C6 as a whole.

The fourth strain body 40D is elastically deformed in the same manner as the first strain body 40A shown in FIG. Decrease.

(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. As described above, the elastically deformable body 41 of each strain body 40A to 40D extends in the Z-axis direction from the support body side end 44 to the force receiving body side end 43. This increases the rigidity of the elastically deformable body 41 against forces in the Z-axis direction, so that the elastically deformable body 41 substantially acts as a rigid body. It can be considered that there is no expansion or contraction of the elastically deformable bodies 41 in the Z-axis direction, and each elastically deformable body 41 does not undergo elastic deformation. Therefore, the capacitance value of each capacitive element C1 to C8 does not change. This is shown as "0 (zero)" in the Fz row in the table shown in FIG.

(When +Mx acts)
Next, a case where a moment Mx (see FIG. 5) around the X-axis (clockwise toward the positive side in the X-axis direction) acts on the force receiving body 20 will be described. In this case, the force Fz acts on the elastically deformable body 41 of the first flexural body 40A in the negative side of the Z-axis direction, and the force Fz acts on the elastically deformable body 41 of the third flexural body 40C on the positive side of the Z-axis direction. A force Fz acts. As described above, the elastically deformable body 41 extends in the Z-axis direction from the support body side end 44 to the force receiving body side end 43. This increases the rigidity of the elastically deformable body 41 against forces in the Z-axis direction, so that the elastically deformable body 41 substantially acts as a rigid body. There is no expansion or contraction of the elastic deformable body 41 in the Z-axis direction, and the force receiving body 20 is not displaced. Since the force receiving body 20 is not displaced, the elastically deformable body 41 of the second strain body 40B is not elastically deformed, and the elastically deformable body 41 of the fourth strain body 40D is also not elastically deformed. Therefore, the capacitance value of each capacitive element C1 to C8 does not change. This is shown as "0 (zero)" in the Mx row in the table shown in FIG.

(When +My acts)
Next, a case where a moment My (see FIG. 5) around the Y-axis (clockwise toward the positive side in the Y-axis direction) acts on the force receiving body 20 will be described. In this case, force Fz acts on the elastically deformable body 41 of the second strain body 40B in the negative side of the Z-axis direction, and force Fz acts on the elastically deformable body 41 of the fourth strain body 40D in the positive side of the Z-axis direction. A force Fz acts. As described above, the elastically deformable body 41 extends in the Z-axis direction from the support body side end 44 to the force receiving body side end 43. This increases the rigidity of the elastically deformable body 41 against forces in the Z-axis direction, so that the elastically deformable body 41 substantially acts as a rigid body. There is no expansion or contraction of the elastic deformable body 41 in the Z-axis direction, and the force receiving body 20 is not displaced. The elastically deformable body 41 of the first strain body 40A is not elastically deformed, and the elastically deformable body 41 of the third strain body 40C is also not elastically deformed. Therefore, the capacitance value of each capacitive element C1 to C8 does not change. This is shown as "0 (zero)" in the My row in the table shown in FIG.

(When +Mz acts)
Next, a case where a moment Mz (see FIG. 5) around the Z axis (clockwise toward the positive side in the Z axis direction) acts on the force receiving body 20 will be described. Also in the following description, the symbols in the table of FIG. 7 are determined according to changes in the capacitance value, as described above.

In this case, the first strain body 40A is elastically deformed in the same way as when the force Fx on the positive side in the X-axis direction is applied. As a result, the first flexural body 40A is elastically deformed in the same way as the first flexural body 40A shown in FIG. The capacitance value increases.

The second strain body 40B is elastically deformed in the same manner as when the force Fy on the positive side in the Y-axis direction is applied. As a result, the second strain body 40B is elastically deformed in the same way as the first strain body 40A shown in FIG. The capacitance value increases.

The third strain body 40C is elastically deformed in the same manner as when the force Fx on the negative side in the X-axis direction is applied. As a result, the capacitance value of the fifth capacitive element C5 decreases, and the capacitance value of the sixth capacitive element C6 increases.

The fourth strain body 40D is elastically deformed in the same manner as when the force Fy on the negative side in the Y-axis direction is applied. As a result, the capacitance value of the seventh capacitive element C7 decreases, and the capacitance value of the eighth capacitive element C8 increases.

In this way, the force sensor 10 according to the present embodiment can detect force Fx, force Fy, and moment Mz. When force Fx, force Fy, and moment Mz act on force receiving body 20, changes in the capacitance values of each capacitive element C1 to C8 are detected, and the direction and magnitude of the force or moment acting on force receiving body 20 are detected. is detected. Then, as shown in FIG. 7, the capacitance value of each capacitive element C1 to C8 changes.

From the table shown in FIG. 7, the forces Fx, Fy and moment Mz acting on the force receiving body 20 can be calculated using the following formula. Thereby, three 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 C1 to C8.
[Formula 3]
Fx=-C1+C2 +C5-C6
[Formula 4]
Fy= -C3+C4 +C7-C8
[Formula 5]
Mz=-C1+C2-C3+C4-C5+C6-C7+C8

As described above, the force sensor 10 shown in FIG. It is now possible to detect axial components.

As described above, according to the present embodiment, the strain elements 40A to 40D connecting the force receiving body 20 and the support body 30 are connected to the support body 30 from the force receiving body side end portion 43 connected to the force receiving body 20. It extends in the Z-axis direction across the support side end 44 . This makes it possible to simplify and simplify the structure of the strain-generating bodies 40A to 40D. In this case, the price of the force sensor 10 can be reduced.

Further, according to the present embodiment, the strain-generating bodies 40A to 40D that connect the force receiving body 20 and the support body 30 are connected to the support body 30 from the force receiving body side end portions 43 connected to the force receiving body 20. The support member side end portion 44 extends in the Z-axis direction. This can suppress elastic deformation of the elastically deformable body 41 in the Z-axis direction. Therefore, even if a force Fz in the Z-axis direction, a moment Mx around the X-axis, or a moment My around the Y-axis acts on the force-receiving body 20, elastic deformation of the elastically deformable body 41 can be suppressed. Therefore, the rigidity against the force Fz, the moment Mx, and the moment My can be increased, and the reliability of the force sensor 10 can be improved.

Further, according to the present embodiment, the displacement beams 42 of the strain-generating bodies 40A to 40D protrude from the elastically deformable body 41 in the second direction orthogonal to the Z-axis direction. Fixed electrode substrates Ef1 to Ef8 are provided on the support body 30, and displacement electrode substrates Ed1 to Ed8 are provided on the displacement beam 42 to face the fixed electrode substrates Ef1 to Ef8. As a result, when the elastically deformable body 41 is elastically deformed in a direction perpendicular to the Z-axis direction, the displacement beam 42 is tilted and displaced. Therefore, the inter-electrode distance between each displacement electrode substrate Ed1 to Ed8 and the corresponding fixed electrode substrate Ef1 to Ef8 can be changed, and the capacitance value of each capacitive element C1 to C8 can be changed. As a result, forces or moments can be detected.

Further, according to the present embodiment, the displacement beams 42 protrude from the elastically deformable body 41 in the second direction on both sides of the elastically deformable body 41. Displacement electrode substrates Ed1 to Ed8 are arranged on each of the displacement beams 42, and fixed electrode substrates Ef1 to Ef8 are arranged on the support body 30 to face the corresponding displacement electrode substrates Ed1 to Ed8. As a result, when the elastically deformable body 41 is elastically deformed in the second direction, some of the displacement electrode substrates Ed1 to Ed8 can be moved away from the corresponding fixed electrode substrates Ef1 to Ef8, and other displacement electrode substrates Ed1 to Ed8 can be moved away from the corresponding fixed electrode substrates Ef1 to Ef8. Ed8 can be brought closer to the corresponding fixed electrode substrates Ef1 to Ef8. Therefore, detection sensitivity can be improved.

Further, according to the present embodiment, the displacement beams 42 of the strain-generating bodies 40A to 40D extend in the second direction orthogonal to the Z-axis direction. That is, the displacement beams 42 of the first strain body 40A and the third strain body 40C extend in the X-axis direction, and the displacement beams 42 of the second strain body 40B and the fourth strain body 40D extend in the Y-axis direction. ing. This allows the displacement beam 42 to be displaced when subjected to the action of the force Fx in the X-axis direction, the force Fy in the Y-axis direction, and the moment Mz about the Z-axis. Therefore, the displacement of the displacement electrode substrates Ed1 to Ed8 can be increased, and the detection sensitivity of force or moment can be increased.

(Second embodiment)
Next, a force sensor according to a second embodiment of the present invention will be described using FIGS. 8 to 10.

The second embodiment shown in FIGS. 8 to 10 is mainly different in that the dimension of the elastically deformable body in the third direction is larger than the dimension of the elastically deformable body in the second direction, and the other configurations are as follows. This embodiment is substantially the same as the first embodiment shown in FIGS. 1 to 7. Note that in FIGS. 8 to 10, the same parts as in the first embodiment shown in FIGS. 1 to 7 are designated by the same reference numerals, and detailed explanations will be omitted.

As shown in FIGS. 8 and 9, the dimension of the elastically deformable body 41 according to the present embodiment in the third direction is larger than the dimension of the elastically deformable body 41 in the second direction. FIG. 8 is a sectional view showing the force sensor 10 according to the second embodiment. FIG. 9 is a plan view showing the force sensor 10 shown in FIG. 8.

The dimension of the elastically deformable body 41 of the first strain body 40A in the Y-axis direction is larger than the dimension of the elastically deformable body 41 in the X-axis direction. The second direction of the first strain body 40A corresponds to the X-axis direction, and the third direction corresponds to the Y-axis direction. In this embodiment, the spring constant of the elastically deformable body 41 of the first strain body 40A with respect to the action of a force in the Y-axis direction is larger than the spring constant with respect to the action of a force in the X-axis direction.

Similarly, the dimension of the elastically deformable body 41 of the second strain body 40B in the X-axis direction is larger than the dimension of the elastically deformable body 41 in the Y-axis direction. The second direction of the second strain body 40B corresponds to the Y-axis direction, and the third direction corresponds to the X-axis direction. In this embodiment, the spring constant of the elastically deformable body 41 of the second strain body 40B with respect to the action of a force in the X-axis direction is larger than the spring constant with respect to the action of a force in the Y-axis direction.

Similarly, the dimension of the elastically deformable body 41 of the third strain body 40C in the Y-axis direction is larger than the dimension of the elastically deformable body 41 in the X-axis direction. The second direction of the third strain body 40C corresponds to the X-axis direction, and the third direction corresponds to the Y-axis direction. In this embodiment, the spring constant of the elastically deformable body 41 of the third strain body 40C with respect to the action of a force in the Y-axis direction is larger than the spring constant with respect to the action of a force in the X-axis direction.

Similarly, the dimension of the elastically deformable body 41 of the fourth strain body 40D in the X-axis direction is larger than the dimension of the elastically deformable body 41 in the Y-axis direction. The second direction of the fourth strain body 40D corresponds to the Y-axis direction, and the third direction corresponds to the X-axis direction. In this embodiment, the spring constant of the elastically deformable body 41 of the fourth strain body 40D with respect to the action of a force in the X-axis direction is larger than the spring constant with respect to the action of a force in the Y-axis direction.

The cross-sectional shape of the elastically deformable body 41 of each strain body 30A to 40D may be rectangular with the third direction as the longitudinal direction, or may be elliptical with the long axis along the third direction. The cross-sectional shape of the elastically deformable body 41 is arbitrary as long as the dimension in the third direction is larger than the dimension in the second direction.

In this embodiment, a case will be described in which a force Fx on the positive side in the X-axis direction is applied to the force receiving body 20.

As described above, the dimension in the X-axis direction of the elastically deformable body 41 of the second strain-generating body 40B is larger than the dimension in the Y-axis direction, and the dimension in the X-axis direction of the elastically deformable body 41 of the fourth strain-generating body 40D is larger. is larger than the dimension in the Y-axis direction. As a result, the second flexure body 40B and the fourth flexure body 40D have increased rigidity against the force Fx, and act substantially as rigid bodies. Therefore, the elastically deformable body 41 of the second strain body 40B and the elastically deformable body 41 of the fourth strain body 40D are not elastically deformed, and the force receiving body 20 is not displaced. Since the force receiving body 20 is not displaced, the elastically deformable body 41 of the first strain body 40A and the elastically deformable body 41 of the third strain body 40C are also not elastically deformed. Therefore, the capacitance value of each capacitive element C1 to C8 does not change.

In this embodiment, a case will be described in which a force Fy on the positive side in the Y-axis direction is applied to the force receiving body 20.

As described above, the dimension in the Y-axis direction of the elastically deformable body 41 of the first strain-generating body 40A is larger than the dimension in the X-axis direction, and the dimension in the Y-axis direction of the elastically deformable body 41 of the third strain-generating body 40C is larger. is larger than the dimension in the X-axis direction. As a result, the first strain body 40A and the third strain body 40C have increased rigidity against the force Fy, and act substantially as rigid bodies. Therefore, the elastically deformable body 41 of the first strain body 40A and the elastically deformable body 41 of the third strain body 40C are not elastically deformed, and the force receiving body 20 is not displaced. Since the force receiving body 20 is not displaced, the elastically deformable body 41 of the second strain body 40B and the elastically deformable body 41 of the fourth strain body 40D are also not elastically deformed. Therefore, the capacitance value of each capacitive element C1 to C8 does not change.

In this embodiment, changes in the capacitance values of the capacitive elements C1 to C8 when a moment Mz around the Z-axis is applied to the force receiving body 20 will be explained using FIG. 10. FIG. 10 is a table showing changes in capacitance values of each capacitive element C1 to C8. In the following description as well, the symbols in the table of FIG. 10 are determined in the same manner as in FIG. 7 according to changes in the capacitance value.

The dimension in the X-axis direction of the elastically deformable body 41 of the first flexure body 40A is smaller than the dimension in the Y-axis direction, and the dimension in the X-axis direction of the elastically deformable body 41 of the third flexure body 40C is smaller in the Y-axis direction. smaller than the dimensions of Thereby, the elastically deformable body 41 of the first flexure body 40A and the elastically deformable body 41 of the third flexure body 40C can be elastically deformed in the X-axis direction.

The dimension in the Y-axis direction of the elastically deformable body 41 of the second flexure body 40B is smaller than the dimension in the X-axis direction, and the dimension in the Y-axis direction of the elastically deformable body 41 of the fourth flexure body 40D is smaller in the X-axis direction. smaller than the dimensions of Thereby, the elastically deformable body 41 of the second strain body 40B and the elastically deformable body 41 of the fourth strain body 40D can be elastically deformed in the Y-axis direction.

Therefore, similarly to the force sensor 10 shown in FIG. 5, the displacement beams 42 of each strain-generating body 40A to 40D are displaced, and the capacitance values of each capacitive element C1 to C8 are changed.

In this way, the force sensor 10 according to this embodiment can detect the moment Mz. When the moment Mz acts on the force receiving body 20, a change in the capacitance value of each capacitive element C1 to C8 is detected, and the direction and magnitude of the moment Mz acting on the force receiving body 20 are detected. Then, as shown in FIG. 10, the capacitance value of each capacitive element C1 to C8 changes.

From the table shown in FIG. 10, the moment Mz acting on the force receiving body 20 can be calculated using the following formula. The following [Formula 6] is the same as the above-mentioned [Formula 5]. Thereby, the uniaxial component of the force, that is, the moment Mz around the Z axis can be calculated.
[Formula 6]
Mz=-C1+C2-C3+C4-C5+C6-C7+C8

In the above-mentioned [Formula 6], the moment Mz is calculated using the capacitance value based on the displacement electrode substrates Ed1 to Ed8 provided on each displacement beam 42. However, the method of calculating the moment Mz according to this embodiment is not limited to this.

For example, the detection element 60 may be configured with an even number of displacement electrode substrates smaller than the number of displacement beams 42. That is, the moment Mz may be detected based on the displacement electrode substrates provided on only some of the displacement beams 42. In this case, each of the several displacement beams 42 may be provided with a displacement electrode substrate, and the other displacement beams 42 may not be provided with a displacement electrode substrate. The fixed electrode substrate may be provided on the support body 30 at a position facing the corresponding displacement electrode substrate. When a moment around the Z-axis is applied to the force sensor 10, some of the displacement electrode substrates move away from the opposing fixed electrode substrate, and the remaining displacement electrode substrates move closer to the opposing fixed electrode substrate. It's okay.

More specifically, the formula for calculating the moment Mz may be any of the following formulas instead of the above-mentioned [Formula 6]. In this case, as shown in [Formula 6], the moment Mz can be calculated without using all of the capacitive elements C1 to C8.
[Formula 7]
Mz=-C1+C2-C5+C6
[Formula 8]
Mz=-C3+C4-C7+C8

When using [Formula 7] and [Formula 8], the detection element 60 can be configured with four displacement electrode substrates, and the displacement beams 42 other than the displacement beams 42 on which these four displacement electrode substrates are provided are , the displacement electrode substrate may not be provided. This allows the number of displacement electrode substrates and the number of fixed electrode substrates to be reduced. The displacement beams 42 that are not provided with displacement electrode substrates can be omitted, and the number of displacement beams 42 can be reduced.

In [Formula 7], when the moment Mz acts, the first displacement electrode substrate Ed1 that constitutes the first capacitive element C1 moves away from the opposing first fixed electrode substrate Ef1, and the The second displacement electrode substrate Ed2 approaches the opposing second fixed electrode substrate Ef2. The fifth displacement electrode substrate Ed5 constituting the fifth capacitive element C5 moves away from the opposing fifth fixed electrode substrate Ef5, and the sixth displacement electrode substrate Ed6 constituting the sixth capacitive element C6 moves away from the opposing sixth fixed electrode substrate Ef5. Approaching Ef6. This makes it possible to prevent variations in the capacitance value due to temperature changes in the capacitive element, as well as to prevent variations in the capacitance value due to common mode noise.

In [Formula 8], when the moment Mz acts, the third displacement electrode substrate Ed3 forming the third capacitive element C3 moves away from the opposing third fixed electrode substrate Ef3, and the third displacement electrode substrate Ed3 forming the fourth capacitive element C4 moves away from the opposing third fixed electrode substrate Ef3. The fourth displacement electrode substrate Ed4 approaches the opposing fourth fixed electrode substrate Ef4. The seventh displacement electrode substrate Ed7 forming the seventh capacitive element C7 moves away from the opposing seventh fixed electrode substrate Ef7, and the eighth displacement electrode substrate Ed8 forming the eighth capacitive element C8 moves away from the opposing eighth fixed electrode substrate Ef7. Approaching Ef8. This makes it possible to prevent variations in the capacitance value due to temperature changes in the capacitive element, as well as to prevent variations in the capacitance value due to common mode noise.

Failure diagnosis may be performed by calculating the moment Mz using both [Formula 7] and [Formula 8] described above and comparing them.

In addition to the above-mentioned [Formula 7] and [Formula 8], the moment Mz can also be calculated using the following formula.

[Formula 9]
Mz=-C1+C4-C5+C6
[Formula 10]
Mz=C2-C3+C6-C7

Also in this case, the number of displacement electrode substrates and the number of fixed electrode substrates can be reduced. The displacement beams 42 that are not provided with displacement electrode substrates can be omitted, and the number of displacement beams 42 can be reduced. Similarly to [Formula 7] and [Formula 8], in [Formula 9] and [Formula 10], fluctuations in capacitance value due to temperature changes in the capacitive element can be prevented, and electrostatic capacitance due to common-mode noise can be prevented. Fluctuations in capacitance value can be prevented. Failure diagnosis may be performed by calculating the moment Mz using both [Formula 9] and [Formula 10] described above and comparing them.

As described above, the elastically deformable body 41 of the force sensor 1 shown in FIG. 9 does not elastically deform in response to force or moment due to axial components other than the moment Mz. As a result, only one of the first to eighth capacitive elements C1 to C8 may be used to calculate the moment Mz. Alternatively, any two of the first to eighth capacitive elements C1 to C8 may be used to calculate the moment Mz.

For example, even if the moment Mz is calculated using a combination of capacitive elements such as -C1+C2, -C3+C4, -C5+C6, -C7+C8 or -C1+C4, C2-C5, -C3+C6, C4-C7, -C5+C8, C6-C7, etc. good.

In this case, the detection element 60 can be configured with two displacement electrode substrates, and no displacement electrode substrates are provided on the displacement beams 42 other than the displacement beams 42 on which these two displacement electrode substrates are provided. Good too. This allows the number of displacement electrode substrates and the number of fixed electrode substrates to be reduced. The displacement beams 42 that are not provided with displacement electrode substrates can be omitted, and the number of displacement beams 42 can be reduced. In addition, similar to [Formula 7] and [Formula 8], it is possible to prevent variations in the capacitance value due to temperature changes of the capacitive element, and also to prevent variations in the capacitance value due to common-mode noise. .

As described above, according to the present embodiment, the dimension of the elastically deformable body 41 of the strain-generating bodies 40A to 40D in the third direction is larger than the dimension of the elastically deformable body 41 in the second direction. Thereby, the rigidity against the force in the third direction can be increased, and elastic deformation of the elastically deformable body 41 in the third direction can be suppressed. Therefore, even if the force Fx in the X-axis direction and the force Fy in the Y-axis direction act on the force receiving body 20, elastic deformation of the elastically deformable body 41 can be suppressed. Therefore, the rigidity against the force Fx and the force Fy can be increased, 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 FIGS. 11 to 13.

In the third embodiment shown in FIGS. 11 to 13, the main difference is that the displacement body protrudes from the elastic deformation body in the second direction on one side of the elastic deformation body and does not protrude on the other side. , the other configurations are substantially the same as the second embodiment shown in FIGS. 8 to 10. Note that in FIGS. 11 to 13, the same parts as those in the second embodiment shown in FIGS. 8 to 10 are designated by the same reference numerals, and detailed explanations will be omitted.

As shown in FIGS. 11 and 12, in this embodiment, the displacement beams 42 of each strain-generating body 40A to 40D protrude from the elastically deformable body 41 in the second direction on one side of the elastically deformable body 41. There is. On the other side of the elastically deformable body 41, the displacement beam 42 does not protrude and is not present. FIG. 11 is a sectional view showing the force sensor 10 according to the third embodiment. FIG. 12 is a plan view showing the force sensor 10 shown in FIG. 11.

The displacement beam 42 of the first strain body 40A and the displacement beam 42 of the second strain body 40B face each other. That is, the displacement beam 42 of the first strain body 40A is arranged on the second strain body 40B side with respect to the elastically deformable body 41 of the first strain body 40A. The displacement beam 42 of the second strain body 40B is arranged on the side of the first strain body 40A with respect to the elastically deformable body 41 of the second strain body 40B. More specifically, the displacement beam 42 of the first strain body 40A is disposed on the positive side in the X-axis direction of the elastically deformable body 41 of the first strain body 40A, and the displacement beam 42 of the second strain body 40B is disposed on the positive side of the elastically deformable body 41 of the first strain body 40A. 42 is arranged on the Y-axis direction negative side of the elastically deformable body 41 of the second strain body 40B. As a result, the displacement beams 42 of the first strain body 40A and the displacement beams 42 of the second strain body 40B face each other.

Similarly, the displacement beams 42 of the third strain body 40C and the displacement beams 42 of the fourth strain body 40D face each other. That is, the displacement beam 42 of the third strain body 40C is arranged on the fourth strain body 40D side with respect to the elastically deformable body 41 of the third strain body 40C. The displacement beam 42 of the fourth strain body 40D is arranged on the third strain body 40C side with respect to the elastically deformable body 41 of the fourth strain body 40D. More specifically, the displacement beam 42 of the third strain body 40C is arranged on the negative side in the X-axis direction of the elastically deformable body 41 of the third strain body 40C, and the displacement beam 42 of the fourth strain body 40D is disposed on the negative side of the elastically deformable body 41 of the third strain body 40C. 42 is arranged on the positive side of the elastically deformable body 41 of the fourth strain body 40D in the Y-axis direction. As a result, the displacement beams 42 of the third strain body 40C and the displacement beams 42 of the fourth strain body 40D face each other.

Each displacement beam 42 is provided with a plurality of displacement electrode substrates. The plurality of displacement electrode substrates are arranged in a third direction orthogonal to the second direction. The support body 30 is provided with fixed electrode substrates facing each displacement electrode substrate.

As shown in FIGS. 11 and 12, the detection element 60 according to the present embodiment includes two fixed electrode substrates Ef21 and Ef22 and two displacement electrode substrates Ed21 and Ed22 as electrodes for the first strain body 40A. , contains. Displacement electrode substrates Ed21 and Ed22 are arranged on the displacement beam 42 of the first strain body 40A. The two displacement electrode substrates Ed21 and Ed22 may be arranged at the end of the displacement beam 42 on the positive side in the X-axis direction. The two displacement electrode substrates Ed21 and Ed22 are arranged at the same position in the X-axis direction, but at different positions in the Y-axis direction. The displacement electrode substrate Ed21 is arranged inside the force sensor 10 in a plan view than the displacement electrode substrate Ed22. More specifically, the displacement electrode substrate Ed21 is arranged on the positive side in the Y-axis direction than the displacement electrode substrate Ed22. The displacement electrode substrate Ed21 is arranged on the negative side in the Y-axis direction than the displacement electrode substrate Ed22.

The fixed electrode substrate Ef21 faces the displacement electrode substrate Ed21. The fixed electrode substrate Ef21 and the displacement electrode substrate Ed21 constitute a twenty-first capacitive element C21. The fixed electrode substrate Ef22 faces the displacement electrode substrate Ed22. The fixed electrode substrate Ef22 and the displacement electrode substrate Ed22 constitute a 22nd capacitive element C22. The 21st capacitive element C21 and the 22nd capacitive element C22 are configured as the detection element 60 for the first strain body 40A.

The configuration of the first strain body 40A and the corresponding detection element 60 described above can be similarly applied to the second strain body 40B, the third strain body 40C, and the fourth strain body 40D.

As shown in FIGS. 11 and 12, the detection element 60 includes two fixed electrode substrates Ef31 and Ef32 and two displacement electrode substrates Ed31 and Ed32 as electrodes for the second strain body 40B. . Displacement electrode substrates Ed31 and Ed32 are arranged on the displacement beam 42 of the second strain body 40B. The two displacement electrode substrates Ed31 and Ed32 may be arranged at the end of the displacement beam 42 on the negative side in the Y-axis direction. The displacement electrode substrate Ed31 is disposed on the negative side of the displacement electrode substrate Ed32 in the X-axis direction and inside the force sensor 10 in plan view.

The fixed electrode substrate Ef31 faces the displacement electrode substrate Ed31. The fixed electrode substrate Ef31 and the displacement electrode substrate Ed31 constitute the 31st capacitive element C31. The fixed electrode substrate Ef32 faces the displacement electrode substrate Ed32. The fixed electrode substrate Ef32 and the displacement electrode substrate Ed32 constitute a 32nd capacitive element C32. The 31st capacitive element C31 and the 32nd capacitive element C32 are configured as the detection element 60 for the second strain body 40B.

As shown in FIGS. 11 and 12, the detection element 60 includes two fixed electrode substrates Ef61 and Ef62 and two displacement electrode substrates Ed61 and Ed62 as electrodes for the third strain body 40C. . Displacement electrode substrates Ed61 and Ed62 are arranged on the displacement beam 42 of the third strain body 40C. The two displacement electrode substrates Ed61 and Ed62 may be arranged at the end of the displacement beam 42 on the negative side in the X-axis direction. The displacement electrode substrate Ed61 is disposed on the negative side of the displacement electrode substrate Ed62 in the Y-axis direction and inside the force sensor 10 in plan view.

The fixed electrode substrate Ef61 faces the displacement electrode substrate Ed61. The fixed electrode substrate Ef61 and the displacement electrode substrate Ed61 constitute the 61st capacitive element C61. The fixed electrode substrate Ef62 faces the displacement electrode substrate Ed62. The fixed electrode substrate Ef62 and the displacement electrode substrate Ed62 constitute the 62nd capacitive element C62. The 61st capacitive element C61 and the 62nd capacitive element C62 are configured as the detection element 60 for the third strain body 40C.

As shown in FIGS. 11 and 12, the detection element 60 includes two fixed electrode substrates Ef71 and Ef72 and two displacement electrode substrates Ed71 and Ed72 as electrodes for the fourth strain body 40D. . Displacement electrode substrates Ed71 and Ed72 are arranged on the displacement beam 42 of the fourth strain body 40D. The two displacement electrode substrates Ed71 and Ed72 may be arranged at the end of the displacement beam 42 on the positive side in the Y-axis direction. The displacement electrode substrate Ed71 is disposed on the positive side of the displacement electrode substrate Ed72 in the X-axis direction and inside the force sensor 10 in plan view.

The fixed electrode substrate Ef71 faces the displacement electrode substrate Ed71. The fixed electrode substrate Ef71 and the displacement electrode substrate Ed71 constitute a 71st capacitive element C71. The fixed electrode substrate Ef72 faces the displacement electrode substrate Ed72. The fixed electrode substrate Ef72 and the displacement electrode substrate Ed72 constitute a 72nd capacitive element C72. The 71st capacitive element C71 and the 72nd capacitive element C72 are configured as the detection element 60 for the fourth strain body 40D.

The force sensor 10 according to this embodiment can detect the moment Mz similarly to the force sensor 10 shown in FIGS. 8 and 9. When the moment Mz acts on the force receiving body 20, a change in the capacitance value of each capacitive element C21 to C72 is detected, and the direction and magnitude of the moment Mz acting on the force receiving body 20 are detected. Then, as shown in FIG. 13, the capacitance value of each capacitive element C21 to C72 changes. FIG. 13 is a table showing changes in capacitance values of each capacitive element C21 to C72.

From the table shown in FIG. 13, the moment Mz acting on the force-receiving body 20 can be calculated using the following equation in the same manner as [Equation 10] described above. The moment Mz can be calculated using the following [Formula 11] and [Formula 12].

[Formula 11]
Mz=C21-C31+C61-C71
[Formula 12]
Mz=C22-C32+C62-C72

Failure diagnosis may be performed by calculating the moment Mz using both [Formula 11] and [Formula 12] above and comparing them. As described in the second embodiment, the moment Mz is calculated by using any two of the capacitive elements C21, C31, C61, and C71, or each of the capacitive elements C22, C32, C62, and C72. Any two of these capacitive elements may be used. For example, the moment Mz may be calculated using a combination of capacitive elements such as +C21-C31, +C61-C71, -C31+C61, +C21-C71, +C22-C32, +C62-C72, -C32+C62, and +C22-C72. In this case, the detection element 60 can be configured with two displacement electrode substrates, and no displacement electrode substrates are provided on the displacement beams 42 other than the displacement beams 42 on which these two displacement electrode substrates are provided. Good too. This allows the number of displacement electrode substrates and the number of fixed electrode substrates to be reduced. The displacement beams 42 that are not provided with displacement electrode substrates can be omitted, and the number of displacement beams 42 can be reduced. Further, it is possible to prevent variations in the capacitance value due to temperature changes of the capacitive element, and also to prevent variations in the capacitance value due to common mode noise.

As described above, according to the present embodiment, the displacement beam 42 protrudes in the second direction on one side of the elastically deformable body 41 of each of the strain-generating bodies 40A to 40D, and does not protrude on the other side. A displacement electrode substrate is arranged on each of the displacement beams 42, and a fixed electrode substrate facing the corresponding displacement electrode substrate is arranged on the support body 30. Thereby, when the elastically deformable body 41 is elastically deformed in the second direction, the inter-electrode distance between the displacement electrode substrate and the corresponding fixed electrode substrate can be changed. Therefore, detection sensitivity can be improved.

Furthermore, according to the present embodiment, the number of displacement beams 42 of the strain-generating bodies 40A to 40D can be reduced. This makes it possible to simplify and simplify the structure of the strain-generating bodies 40A to 40D. In this case, the price of the force sensor 10 can be reduced.

Further, according to the present embodiment, similarly to the force sensor 10 shown in FIGS. 8 to 10, when the force Fx in the X-axis direction and the force Fy in the Y-axis direction are applied to the force receiving body 20, Even if the elastically deformable body 41 is elastically deformed, it can be suppressed. Therefore, the rigidity against the force Fx and the force Fy can be increased, and the reliability of the force sensor 10 can be improved.

Further, according to the present embodiment, each displacement beam 42 is provided with a plurality of displacement electrode substrates Ed21 to Ed72, and the support body 30 is provided with fixed electrode substrates Ef21 to Ef72 facing each displacement electrode substrate Ed21 to Ed72. It is provided. As a result, the moment Mz calculated from the change in the capacitance value of the capacitive elements C21, C31, C61, and C71 including one of the displacement electrode substrates Ed21, Ed31, Ed61, and Ed71 provided on each displacement beam 42, Failure diagnosis can be performed using the moment Mz calculated from the changes in the capacitance values of the capacitive elements C22, C32, C62, and C72 including the other displacement electrode substrate Ed22, Ed32, Ed62, and Ed72. Therefore, the reliability of the force sensor 10 can be improved.

Further, according to the present embodiment, the displacement beams 42 of the first strain body 40A and the displacement beams 42 of the second strain body 40B face each other. The displacement beam 42 of the third strain body 40C and the displacement beam 42 of the fourth strain body 40D face each other. This makes it possible to improve the workability of connecting the electrical wiring to each of the displacement electrode substrates Ed21 to Ed72 and each of the fixed electrode substrates Ef21 to Ef72.

In the present embodiment described above, an example has been described in which each displacement beam 42 is provided with two displacement electrode substrates Ed21 to Ed72. However, it is not limited to this. For example, as described above, the two displacement electrode substrates provided on each displacement beam 42 may be integrated into one displacement electrode substrate. In this case, the two fixed electrode substrates facing one displacement electrode substrate may be formed separately and separated from each other. Alternatively, the two fixed electrode substrates facing each displacement beam 42 may be integrated into one fixed electrode substrate. In this case, the two displacement electrode substrates facing one fixed electrode substrate may be formed separately and separated from each other.

(Fourth embodiment)
Next, a force sensor according to a fourth embodiment of the present invention will be described using FIG. 14.

In the fourth embodiment shown in FIG. 14, the force receiving body has a first force receiving body opening that separates the force receiving body side end portion of the first strain body and the force receiving body side end portion of the second strain body. The main difference is that it includes a second force-receiving body opening that separates the force-receiving body-side end of the third strain-generating body and the force-receiving body-side end of the fourth strain-generating body; This embodiment is substantially the same as the third embodiment shown in FIGS. 11 to 13. Note that in FIG. 14, the same parts as in the third embodiment shown in FIGS. 11 to 13 are given the same reference numerals, and detailed explanations will be omitted.

As shown in FIG. 14, in this embodiment, the force receiving body 20 may include a first force receiving body opening 21 and a second force receiving body opening 22. FIG. 14 is a perspective view showing a force sensor 10 according to a fourth embodiment.

The first force receiving body opening 21 is formed so as to separate the force receiving body side end portion 43 of the first strain body 40A from the force receiving body side end portion 43 of the second strain body 40B. As a result, the force-receiving body side end portion 43 of the first strain-generating body 40A and the force-receiving body-side end portion 43 of the second strain-generating body 40B are not connected by the member that constitutes the force-receiving body 20, far from each other. When viewed from the positive side in the Z-axis direction, from the first force-receiving body opening 21, the displacement beam 42 of the first strain body 40A, the displacement beam 42 of the second strain body 40B, and the first support connection portion described below 33 is exposed.

The second force receiving body opening 22 is formed to separate the force receiving body side end portion 43 of the third strain generating body 40C from the force receiving body side end portion 43 of the fourth strain generating body 40D. As a result, the force-receiving body side end portion 43 of the third strain-generating body 40C and the force-receiving body-side end portion 43 of the fourth strain-generating body 40D are not connected by the member constituting the force-receiving body 20, far from each other. When viewed from the positive side in the Z-axis direction, from the second force receiving body opening 22, the displacement beam 42 of the third strain body 40C, the displacement beam 42 of the fourth strain body 40D, and the second support connection portion described below 34 is exposed.

The force receiving body 20 may include a first force receiving body connecting portion 23 and a second force receiving body connecting portion 24. The first force receiving body connecting portion 23 connects the force receiving body side end portion 43 of the second strain body 40B and the force receiving body side end portion 43 of the third strain body 40C. The second force receiving body connecting portion 24 connects the force receiving body side end portion 43 of the fourth strain body 40D and the force receiving body side end portion 43 of the first strain body 40A. When the force-receiving body 20 includes the force-receiving body center opening 20a, the planar shape of the first force-receiving body connecting portion 23 and the planar shape of the second force-receiving body connecting portion 24 are generally circular ring-shaped. The shape may be 1/4.

Bolt holes 25 may be provided in the first force receiving body connecting portion 23 and the second force receiving body connecting portion 24. Bolt holes 25 may be used to attach tool 3 shown in FIG. 1 or an end effector not shown.

As shown in FIG. 14, in this embodiment, the support 30 may include a first support opening 31 and a second support opening 32.

The first support opening 31 is formed to separate the support side end portion 44 of the second strain body 40B from the support side end portion 44 of the third strain body 40C. As a result, the support side end portion 44 of the second flexure body 40B and the support body side end portion 44 of the third flexure body 40C are not connected by the member constituting the support body 30, but are separated from each other. There is. When viewed from the negative side in the Z-axis direction, the first force-receiving body connecting portion 23 described above is exposed from the first support body opening 31.

The second support opening 32 is formed to separate the support side end portion 44 of the fourth strain body 40D from the support body side end portion 44 of the first strain body 40A. As a result, the support-side end portion 44 of the fourth strain-generating body 40D and the support-side end portion 44 of the first strain-generating body 40A are not connected by the member constituting the support body 30, but are separated from each other. There is. When viewed from the negative side in the Z-axis direction, the second force-receiving body connection portion 24 described above is exposed from the second support body opening 32.

As shown in FIG. 14, in this embodiment, the support body 30 may include a first support body connection part 33 and a second support body connection part 34. The first support connecting portion 33 connects the support side end portion 44 of the first strain body 40A and the support body side end portion 44 of the second strain body 40B. The second support connecting portion 34 connects the support side end portion 44 of the third strain body 40C and the support body side end portion 44 of the fourth strain body 40D. When the support body 30 includes the support body center opening 30a, the planar shape of the first support body connection part 33 and the plane shape of the second support body connection part 34 are approximately 1/4 of the circular ring shape. It may be a shape.

Bolt holes 35 may be provided in the first support connection part 33 and the second support connection part 34. Bolt holes 35 may be used for attachment to the robot arm 4 shown in FIG.

Each of the strain-generating bodies 40A to 40D shown in FIG. 14 may be configured similarly to each of the strain-generating bodies 40A to 40D shown in FIGS. 11 and 12. The detection element 60 may also be configured similarly to the detection element 60 shown in FIGS. 11 and 12. In this case, the direction and magnitude of the moment Mz acting on the force sensor 10 can be detected in the same way, and detection sensitivity can be improved. In FIG. 14, each capacitive element C1 to C8 is omitted for clarity of the drawing.

As described above, according to the present embodiment, the force-receiving body 20 has a first strain-generating body 40A separated from the force-receiving body-side end 43 of the second strain-generating body 40B. The first force-receiving body opening 21, the second force-receiving body opening 22 that separates the force-receiving body side end 43 of the third strain-generating body 40C, and the force-receiving body-side end 43 of the fourth strain-generating body 40D. Contains. This allows the mass of the force receiving body 20 to be reduced. Therefore, the ease of handling the force sensor 10 can be improved.

Further, according to the present embodiment, the support body 30 has a first support opening that separates the support side end portion 44 of the second strain body 40B and the support body side end portion 44 of the third strain body 40C. 31, and a second support opening 32 that separates the support side end portion 44 of the fourth strain body 40D and the support body side end portion 44 of the first strain body 40A. This allows the mass of the support body 30 to be reduced. Therefore, the ease of handling the force sensor 10 can be improved.

(Fifth embodiment)
Next, a force sensor according to a fifth embodiment of the present invention will be described using FIGS. 15 to 20.

In the fifth embodiment shown in FIGS. 15 to 20, the main difference is that the force-receiving body includes a force-receiving body main body portion and a force-receiving body thin portion that is thinner than the force-receiving body main body portion. , the other configurations are substantially the same as the first embodiment shown in FIGS. 1 to 7. Note that in FIGS. 15 to 20, parts that are the same as those in the first embodiment shown in FIGS. 1 to 7 are given the same reference numerals, and detailed explanations will be omitted.

As shown in FIGS. 15 and 16, the force-receiving body 20 according to the present embodiment includes a force-receiving body main body portion 26 and a force-receiving body thin portion 27. The force-receiving body main body portion 26 is a relatively thick portion of the force-receiving body 20. The force-receiving body thin portion 27 is a portion thinner than the force-receiving body main body portion 26. The force receiving body thin portion 27 has flexibility and can be elastically deformed by the action of a force in the Z-axis direction. The spring constant of the force-receiving body thin portion 27 with respect to the action of a force in the Z-axis direction is smaller than the spring constant of the force-receiving body main body portion 26 with respect to the action of a force in the Z-axis direction. The planar shape of the force-receiving body thin portion 27 may be circular or rectangular, and is arbitrary. As shown in FIG. 16, the planar shape of the force receiving body thin portion 27 may be approximately circular. FIG. 15 is a sectional view showing the force sensor 10 according to the fifth embodiment. FIG. 16 is a plan view showing the force sensor 10 shown in FIG. 15.

In the Z-axis direction, the surface of the force-receiving body thin portion 27 on the support body 30 side may be formed at the same position as the surface of the force-receiving body main body portion 26 on the support body 30 side. In this case, the surface of the force-receiving body main body portion 26 and the surface of the force-receiving body thin portion 27 may constitute a continuous surface. The surface of the force-receiving body thin portion 27 on the side opposite to the support body 30 is arranged at a position closer to the support body 30 than the surface of the force-receiving body main body portion 26 on the side opposite to the support body 30. As a result, a recess 28 is formed on the surface of the force receiving body 20 opposite to the support body 30.

The force receiving body thin portion 27 is connected to the force receiving body side end portions 43 of the strain generating bodies 40A to 40D. The force receiving body 20 includes four force receiving body thin portions 27. Each force-receiving body thin portion 27 is arranged at a position overlapping the elastically deformable body 41 of the corresponding strain-generating body 40A to 40D in plan view. At the center of each force receiving body thin portion 27, the force receiving body side end portion 43 of the corresponding elastic deformable body 41 may be arranged. The force receiving body thin portions 27 are separated from each other and are not connected to each other. One or more through holes (not shown) may be formed in the force receiving body thin portion 27. The through hole is a hole that penetrates the force receiving body thin portion 27. The through hole may be arranged at a position that does not overlap the force receiving body side end portion 43 in plan view. By forming the through hole, the flexibility of the force receiving body thin portion 27 can be increased.

As shown in FIGS. 15 and 16, the support 30 according to this embodiment includes a support main body portion 36 and a support thin portion 37. As shown in FIGS. The support body portion 36 is a relatively thick portion of the support body 30. The support thin portion 37 is thinner than the support main body portion 36. The thin support portion 37 is flexible and can be elastically deformed by a force in the Z-axis direction. The spring constant of the thin support portion 37 with respect to the action of a force in the Z-axis direction is smaller than the spring constant of the support body portion 36 with respect to the action of a force in the Z-axis direction. The planar shape of the support thin portion 37 may be circular or rectangular, and is arbitrary. The planar shape of the support body thin part 37 may be approximately circular like the force receiving body thin part 27 described above.

In FIG. 16, the planar shape of the elastically deformable body 41 is approximately circular, but the shape is not limited to this.

In the Z-axis direction, the surface of the support thin portion 37 on the force-receiving body 20 side may be formed at the same position as the surface of the support main body portion 36 on the force-receiving body 20 side. In this case, the surface of the support body portion 36 and the surface of the support thin portion 37 may constitute a continuous surface. The surface of the thin support portion 37 opposite to the force receiving body 20 is located closer to the force receiving body 20 than the surface of the support main body portion 36 opposite to the force receiving body 20 . As a result, a recess 38 is formed on the surface of the support body 30 opposite to the force-receiving body 20 .

The thin support portion 37 is connected to the support side end portions 44 of the strain-generating bodies 40A to 40D. The support body 30 includes four support body thin parts 37. Each support thin portion 37 is arranged at a position overlapping the elastically deformable body 41 of the corresponding strain-generating body 40A to 40D in plan view. The support side end portion 44 of the corresponding elastically deformable body 41 may be arranged at the center of each support thin portion 37 . The thin support portions 37 are separated from each other and are not connected to each other. One or more through holes (not shown) may be formed in the thin support portion 37 . The through hole is a hole that penetrates the support thin portion 37. The through hole may be arranged at a position that does not overlap the support side end portion 44 in plan view. By forming the through holes, the flexibility of the thin support portion 37 can be increased.

Next, a method for detecting force or moment in the force sensor according to the present embodiment having such a configuration will be described.

When a force Fx in the X-axis direction acts on the first strain body 40A according to the present embodiment, the electrostatic charge of the first capacitive element C1 is The capacitance value decreases, and the capacitance value of the second capacitive element C2 increases. In this case, the force Fx is expressed by the above-mentioned [Formula 1].

Even when the moment My around the Y-axis acts on the first flexural body 40A according to the present embodiment, the electrostatic charge of the first capacitive element C1 is The capacitance value decreases, and the capacitance value of the second capacitive element C2 increases. In this case, the moment My is expressed by the above-mentioned [Formula 2].

When a force Fy in the Y-axis direction acts on the single first strain body 40A according to the present embodiment, the electrostatic charge in each capacitive element C1 and C2 similarly to the first strain body 40A shown in FIG. It can be assumed that there is no change in the capacitance value. Similarly, when the moment Mx around the X-axis is applied, it can be assumed that there is no change in the capacitance value in each capacitive element C1, C2.

A case where a force Fz in the Z-axis direction is applied to the first strain body 40A alone according to the present embodiment will be described with reference to FIGS. 17 and 18. FIG. 17 is a front view schematically showing a deformed state of the first strain body 40A when the force receiving body 20 receives a force Fz on the positive side in the Z-axis direction. FIG. 18 is a front view schematically showing a deformed state of the first strain body 40A when the force receiving body 20 receives a force Fz on the negative side in the Z-axis direction.

When a force Fz is applied to the first strain body 40A in the positive direction in the Z-axis direction, the force receiving body thin portion 27 and the support body thin portion 37 are elastically deformed, as shown in FIG. In this case, the force receiving body 20 is displaced to the positive side in the Z-axis direction, and the elastically deformable body 41 of the first strain body 40A and the displacement beam 42 are displaced to the positive side in the Z-axis direction. The elastically deformable body 41 does not elastically deform in the Z-axis direction. As a result, the first displacement electrode substrate Ed1 rises and moves away from the first fixed electrode substrate Ef1. 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, and the capacitance value of the first capacitive element C1 decreases. Similarly, the second displacement electrode substrate Ed2 also rises and moves away from the second fixed electrode substrate Ef2. The inter-electrode distance between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 increases, and the capacitance value of the second capacitive element C2 decreases.

The force Fz acting on the group of the first strain body 40A can be calculated using the following formula.
[Formula 13]
Fz=-C1-C2

On the other hand, when force Fz is applied to the first strain body 40A in the negative direction in the Z-axis direction, the force receiving body thin part 27 and the support body thin part 37 are elastically deformed, as shown in FIG. In this case, the force receiving body 20 is displaced to the negative side in the Z-axis direction, and the elastically deformable body 41 of the first strain body 40A and the displacement beam 42 are displaced to the negative side in the Z-axis direction. The elastically deformable body 41 does not elastically deform in the Z-axis direction. As a result, the first displacement electrode substrate Ed1 descends and approaches the first fixed electrode substrate Ef1. 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, and the capacitance value of the first capacitive element C1 increases. Similarly, the second displacement electrode substrate Ed2 also descends and approaches the second fixed electrode substrate Ef2. The inter-electrode distance between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 decreases, and the capacitance value of the second capacitive element C2 increases.

In this way, the force sensor 10 in which the force receiving body 20 and the support body 30 are connected only by the first strain body 40A can detect the force Fx, the force Fz, and the moment My. This force sensor 10 may be used in an environment where only one of force Fx and moment My acts.

Next, each capacitive element C1 when a force Fz in the Z-axis direction, a moment Mx around the X-axis, and a moment My around the Y-axis act on the force receiving body 20 of the force sensor 10 shown in FIGS. 15 and 16. The change in the capacitance value of ~C8 will be explained using FIG. 19. The change in the capacitance value of each capacitive element C1 to C8 when a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a moment Mz around the Z-axis is applied is the static change in the force sensor 10 shown in FIG. This is similar to the change in capacitance value. Therefore, a detailed explanation of the force Fx, the force Fy, and the moment Mz will be omitted. FIG. 19 is a table showing changes in capacitance values of each capacitive element C1 to C8.

(When +Fz acts)
A case where force Fz acts on the force receiving body 20 in the positive direction in the Z-axis direction will be described.

In this case, the first strain body 40A is elastically deformed as shown in FIG. 17, and the capacitance value of the first capacitive element C1 decreases, and the capacitance value of the second capacitive element C2 decreases. This is shown as "- (minus)" in C1 and C2 of the Fz row in the table shown in FIG.

The second strain body 40B is elastically deformed similarly to the first strain body 40A shown in FIG. As a result, the capacitance value of the third capacitive element C3 decreases, and the capacitance value of the fourth capacitive element C4 decreases. The third strain body 40C and the fourth strain body 40D similarly deform elastically, and the capacitance values of the fifth to eighth capacitance elements C5 to C8 decrease.

(When +Mx acts)
A case where a moment Mx around the X axis acts on the force receiving body 20 will be explained.

In this case, the first flexural body 40A is elastically deformed in the same way as the first flexural body 40A shown in FIG. The capacitance value increases.

In the second strain body 40B, since the elastic deformable body 41 is located at the same position as the center O of the force receiving body 20 in the Y-axis direction, the displacement of the displacement beam 42 of the second strain body 40B is This is smaller than the displacement of the displacement beam 42 of the first strain body 40A and the displacement of the displacement beam 42 of the third strain body 40C. Here, in order to simplify the explanation, it is assumed that the displacement beam 42 of the second strain body 40B is not displaced. Therefore, the capacitance value of the third capacitive element C3 does not change, and the capacitance value of the fourth capacitive element C4 also does not change.

The third flexural body 40C is elastically deformed in the same way as the first flexural body 40A shown in FIG. Decrease.

In the fourth strain body 40D, since the elastically deformable body 41 is located at the same position as the center O of the force receiving body 20 in the Y-axis direction, the displacement of the displacement beam 42 of the fourth strain body 40D is This is smaller than the displacement of the displacement beam 42 of the first strain body 40A and the displacement of the displacement beam 42 of the third strain body 40C. Here, in order to simplify the explanation, it is assumed that the displacement beam 42 of the fourth strain body 40D is not displaced. Therefore, the capacitance value of the seventh capacitive element C7 does not change, and the capacitance value of the eighth capacitive element C8 also does not change.

(When +My acts)
A case where a moment My around the Y axis acts on the force receiving body 20 will be explained.

In this case, in the first strain body 40A, since the elastically deformable body 41 is located at the same position as the center O of the force receiving body 20 in the X-axis direction, the displacement beam 42 of the first strain body 40A is The displacement is smaller than the displacement of the displacement beam 42 of the second strain body 40B and the displacement of the displacement beam 42 of the fourth strain body 40D. Here, in order to simplify the explanation, it is assumed that the displacement beam 42 of the first strain body 40A is not displaced. Therefore, the capacitance value of the first capacitive element C1 does not change, and the capacitance value of the second capacitive element C2 also does not change.

The second flexural body 40B is elastically deformed in the same way as the first flexural body 40A shown in FIG. increase

In the third strain body 40C, since the elastic deformation body 41 is located at the same position as the center O of the force receiving body 20 in the X-axis direction, the displacement of the displacement beam 42 of the third strain body 40C is This is smaller than the displacement of the displacement beam 42 of the second strain body 40B and the displacement of the displacement beam 42 of the fourth strain body 40D. Here, in order to simplify the explanation, it is assumed that the displacement beam 42 of the third strain body 40C is not displaced. Therefore, the capacitance value of the fifth capacitive element C5 does not change, and the capacitance value of the sixth capacitive element C6 also does not change.

The fourth strain body 40D is elastically deformed in the same way as the first strain body 40A shown in FIG. Decrease.

In this way, the force sensor 10 according to the present embodiment can detect force Fx, force Fy, force Fz, moment Mx, moment My, and moment Mz, and can detect six-axis components. When force Fx, force Fy, force Fz, moment Mx, moment My, and moment Mz act on force receiving body 20, changes in the capacitance values of each capacitive element C1 to C8 are detected, and the force acting on force receiving body 20 is detected. The direction and magnitude of the applied force or moment are detected. Then, as shown in FIG. 19, the capacitance value of each capacitive element C1 to C8 changes.

From the table shown in FIG. 19, Fx, force Fy, force Fz, moment Mx, moment My, and moment Mz acting on the force receiving body 20 can be calculated using the following equations. Thereby, six axial components of force can be detected.
[Formula 14]
Fx=-C1+C2 +C5-C6
[Formula 15]
Fy= -C3+C4 +C7-C8
[Formula 16]
Fz=-C1-C2-C3-C4-C5-C6-C7-C8
[Formula 17]
Mx= C1+C2 -C5-C6
[Formula 18]
My=C3+C4 -C7-C8
[Formula 19]
Mz=-C1+C2-C3+C4-C5+C6-C7+C8

As described above, the force sensor 10 shown in FIGS. 15 and 16 has force Fx, force Fy, force Fz, moment Mx, moment My, and Since the moment Mz can be detected, it is possible to detect the 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. Although a detailed explanation will be omitted, for example, by using three strain-generating bodies, six-axis components of force and moment can be detected.

When the changes in the capacitance values of the capacitive elements C1 to C8 shown in FIG. 19 are applied to the above-mentioned [Formula 14] to [Formula 19], a table showing the main axis sensitivity and other axis sensitivity in FIG. 20 is obtained. FIG. 20 is a table showing the main axis sensitivity and other axis sensitivity based on the change in capacitance value shown in FIG. 19. VFx shown in Fig. 20 is the output when force Fx in the X-axis direction is applied, VFy is the output when force Fy in the Y-axis direction is applied, and VFz is the output when force Fz in the Z-axis direction is applied. This is the output of Also, VMx is the output when the moment Mx around the X axis acts, VMy is the output when the moment My around the Y axis acts, and VMz is the output when the moment Mz around the Z axis acts. It is.

The numerical values shown in the table of FIG. 20 indicate that the capacitive elements marked with a "+" sign are "+1" for each force Fx, Fy, Fz and each moment Mx, My, Mz listed in the table of FIG. '', and the capacitive element with the sign "-" is set as "-1", and these are the numerical values obtained by substituting it into the right-hand side of the above-mentioned [Formula 14] to [Formula 19]. For example, the value "4" written in the square where the Fx column and the VFx row intersect is "+1" in C2 and C5 based on the Fx row in FIG. 19 in [Formula 14] indicating Fx. This is the numerical value obtained by substituting "-1" into C1 and C6. In addition, the numerical value "0" written in the square where the Fx column and the VFy row intersect is applied to C1, C2, C5, and C6 based on the Fy row in FIG. 19 in [Formula 14] indicating Fx. This is the numerical value obtained by substituting 0.

As shown in FIG. 20, regarding force Fx, VFx has a numerical value of "4", but VFy, VFz, VMx, VMy, and VMz have numerical values of "0". From this, regarding the force Fx, there is no other axis sensitivity, and only the main axis sensitivity can be detected. Similarly, there is no other axis sensitivity for the forces Fy, Fz and the moments Mx, My, Mz, and only the main axis sensitivity can be detected. In other words, it is possible to obtain the force sensor 10 that can suppress the occurrence of other axis sensitivity.

Note that there may also be cases where sensitivity in other axes occurs. For example, when force Fz acts on the first strain body 40A in the positive direction of the Z-axis, 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 may be different. In this case, other axis sensitivity may occur with respect to force Fz. Furthermore, when force Fz and moments Mx and My act on the force-receiving body 20, the first strain body 40A is displaced in the Z-axis direction. In the My row, the amount of change in capacitance value may be different even if the same reference numerals are assigned. In this case, sensitivity to other axes may occur with respect to force Fz, moments Mx, and My. Sensitivity to other axes may similarly occur with respect to forces Fx, Fy, and moment Mz. For example, when the moment Mx acts on the force receiving body 20, as shown in FIG. 19, the capacitance value is Although the value "0" is written because it does not change, the capacitance value may change and other axis sensitivity may occur. The same applies to moments My and Mz. Furthermore, in the rows of forces Fx and Fy, the capacitance values of capacitive elements for which a numerical value of "0" is written may change and other-axis sensitivity may occur.

However, even when other-axis sensitivity occurs, the inverse matrix of the other-axis sensitivity matrix (a 6-by-6 matrix corresponding to the table shown in Figure 20, also referred to as a characteristic matrix) is calculated, and this inverse matrix is Correction calculation can be performed by multiplying the output (characteristic matrix) of the force sensor. As a result, the other axis sensitivity can be reduced, and the occurrence of other axis sensitivity can be suppressed.

As described above, according to the present embodiment, the force receiving body 20 includes the force receiving body main body portion 26 and the force receiving body thin wall portion 27 which is thinner than the force receiving body main body portion 26, and includes the force receiving body thin wall portion 27. 27 is connected to the force-receiving body side end portion 43 of the strain-generating bodies 40A to 40D. As a result, the force-receiving body thin portion 27 can be elastically deformed by the action of a force in the Z-axis direction, and when a force in the Z-axis direction is applied to the force-receiving body 20, the force-receiving body 20 is can be displaced in the direction. Therefore, the displacement beams 42 of the strain bodies 40A to 40D can be displaced, and the capacitance values of the capacitive elements C1 to C8 can be changed. As a result, six axial components of force or moment can be detected.

Further, according to the present embodiment, the support body 30 includes a support body portion 36 and a support thin portion 37 that is thinner than the support body portion 36, and the support thin portion 37 is a strain-generating body. It is connected to the support side end portion 44 of 40A to 40D. As a result, the support body thin portion 37 can be elastically deformed by the action of a force in the Z-axis direction, and when a force in the Z-axis direction is applied to the force-receiving body 20, the force-receiving body 20 is moved in the Z-axis direction. can be displaced to Therefore, the displacement beams 42 of the strain bodies 40A to 40D can be displaced, and the capacitance values of the capacitive elements C1 to C8 can be changed. As a result, six axial components of force or moment can be detected.

In addition, in this embodiment mentioned above, the example where the planar shape of the force receiving body thin part 27 was circular was demonstrated. However, it is not limited to this. For example, the planar shape of the force receiving body thin portion 27 may be a circular ring shape. In this case, the force receiving body thin portion 27 may surround the force receiving body side end portion 43 in plan view. In plan view, the inner part of the force-receiving body thin part 27 has the same thickness as the force-receiving body main body part 26, and the force-receiving body side end part 43 is connected to the force-receiving body thin part 27 through this inner part. It may also be connected. In this case as well, the above-described through hole may be formed in the force receiving body thin portion 27. The planar shape of the force-receiving body thin portion 27 may be formed in a rectangular annular shape. In this case, the cross-sectional shape of the elastically deformable body 41 along the XY plane may also be rectangular.

Furthermore, in the present embodiment described above, an example in which the planar shape of the thin support portion 37 is circular has been described. However, it is not limited to this. For example, the planar shape of the thin support portion 37 may be a circular ring shape. In this case, the thin support portion 37 may surround the support side end portion 44 in plan view. In plan view, the inner part of the thin support part 37 has the same thickness as the support main body part 36, and the support side end part 44 is connected to the thin support part 37 through this inner part. You can also do this. In this case as well, the above-mentioned through hole may be formed in the thin support portion 37. The planar shape of the thin support portion 37 may be formed into a rectangular annular shape. In this case, the cross-sectional shape of the elastically deformable body 41 along the XY plane may also be rectangular.

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.

1 Robot 10 Force sensor 20 Force receiving body 21 First force receiving body opening 22 Second force receiving body opening 26 Force receiving body main body portion 27 Force receiving body thin wall portion 30 Support body 31 First support body opening 32 Second support body Opening 36 Support main body portion 37 Support thin wall portion 40 Strain body 40A First strain body 40B Second strain body 40C Third strain body 40D Fourth strain body 41 Elastic deformation body 42 Displacement beam 43 Force receiving body side End portion 44 Support side end portion 60 Detection element 70 Detection circuit Ed1 to Ed8, Ed21, Ed22, Ed31, Ed32, Ed61, Ed62, Ed71, Ed72 Displacement electrode substrate Ef1 to Ef8, Ef21, Ef22, Ef31, Ef32, Ef61, Ef62 , Ef71, Ef72 fixed electrode substrate

Claims (13)

a force receiving body subjected to the action of a force or moment to be detected;
a support body disposed on one side of the force receiving body in a first direction and supporting the force receiving body;
a strain-generating body connecting the force receiving body and the support body;
a detection element that detects displacement caused by the action of force or moment applied to the force receiving body ;
A detection circuit that outputs an electric signal indicating the force or moment acting on the force receiving body based on the detection result of the detection element,
The strain body includes a connecting body extending in the first direction from a force receiving body side end connected to the force receiving body to a support side end connected to the support body, and a connecting body extending in the first direction from the connecting body to the support side end connected to the support body. a displacement body protruding in a second direction perpendicular to;
The force-receiving body includes a force-receiving body main body portion, and a force-receiving body thin portion that is thinner than the force-receiving body main body portion and connected to the force-receiving body side end portion of the flexure body,
The detection element is a force sensor including a fixed electrode substrate provided on the support body and a displacement electrode substrate provided on the displacement body and facing the fixed electrode substrate. The force according to claim 1, wherein the support body includes a support body part and a support thin part that is thinner than the support body part and connected to the support body side end part of the flexure body. sense sensor. A direction perpendicular to the first direction and the second direction is a third direction,
The force sensor according to claim 1 or 2 , wherein a dimension of the connecting body in the third direction is larger than a dimension of the connecting body in the second direction. The strain body includes two displacement bodies protruding in the second direction on both sides of the connection body,
The detection element includes two of the fixed electrode substrates and two of the displacement electrode substrates facing the corresponding fixed electrode substrates,
The force sensor according to claim 1 or 2, wherein each of the displacement bodies is provided with the displacement electrode substrate. The force-receiving body and the support body are connected by the four strain-generating bodies,
The four strain bodies include a first strain body, a second strain body, a third strain body, and a fourth strain body,
The first direction is the Z-axis direction in the XYZ three-dimensional coordinate system,
When viewed in the Z-axis direction, the first strain body is arranged on the negative side in the Y-axis direction with respect to the center of the force-receiving body, and on the positive side in the X-axis direction with respect to the center of the force-receiving body. The second strain-generating body is arranged, the third strain-generating body is arranged on the positive side in the Y-axis direction with respect to the center of the force-receiving body, and the third strain-generating body is arranged on the negative side in the X-axis direction with respect to the center of the force-receiving body. the fourth strain body is arranged,
The second direction of the first flexural body and the third flexural body is the X-axis direction,
The force sensor according to claim 1 or 2, wherein the second direction of the second strain body and the fourth strain body is the Y-axis direction. The force sensor according to claim 1 or 2, wherein the displacement body projects from the connection body in the second direction on one side of the connection body and does not protrude on the other side. The displacement body is provided with a plurality of the displacement electrode substrates,
The force sensor according to claim 6 , wherein the support body is provided with the fixed electrode substrate facing each of the displacement electrode substrates. The force-receiving body and the support body are connected by the four strain-generating bodies,
The four strain bodies include a first strain body, a second strain body, a third strain body, and a fourth strain body,
The first direction is the Z-axis direction in the XYZ three-dimensional coordinate system,
When viewed in the Z-axis direction, the first strain body is arranged on the negative side in the Y-axis direction with respect to the center of the force-receiving body, and on the positive side in the X-axis direction with respect to the center of the force-receiving body. The second strain-generating body is arranged, the third strain-generating body is arranged on the positive side in the Y-axis direction with respect to the center of the force-receiving body, and the third strain-generating body is arranged on the negative side in the X-axis direction with respect to the center of the force-receiving body. the fourth strain body is arranged,
The second direction of the first flexural body and the third flexural body is the X-axis direction,
The second direction of the second flexure body and the fourth flexure body is the Y-axis direction,
The displacement body of the first strain body and the displacement body of the second strain body face each other,
The force sensor according to claim 6 , wherein the displacement body of the third strain body and the displacement body of the fourth strain body face each other. The force receiving body includes a first force receiving body opening that separates the force receiving body side end portion of the first strain body and the force receiving body side end portion of the second strain body, and the third strain body. The force sensor according to claim 8 , further comprising a second force receiving body opening that separates the force receiving body side end portion of the fourth strain body from the force receiving body side end portion of the fourth strain body. The support body includes a first support opening that separates the support side end portion of the second strain body and the support body side end portion of the third strain body, and a first support opening that separates the support side end portion of the fourth strain body. The force sensor according to claim 8 , comprising a second support opening that separates the end portion and the support side end portion of the first strain body. The force-receiving body and the support body are connected by a plurality of the strain-generating bodies,
The detection element is configured with an even number of the displacement electrode substrates, which is smaller than the number of the displacement bodies,
Each of some of the displacement bodies is provided with the displacement electrode substrate, and other displacement bodies are not provided with the displacement electrode substrate,
When a moment around the axis along the first direction acts on the force sensor, some of the displacement electrode substrates move away from the opposing fixed electrode substrate, and the remaining displacement electrode substrates move away from the opposing fixed electrode substrate. The force sensor according to claim 1 or 2, which approaches the fixed electrode substrate. The force sensor according to claim 11 , wherein the strain body includes two displacement bodies protruding in the second direction on both sides of the connection body. The force sensor according to claim 11 , wherein the displacement body projects from the connection body in the second direction on one side of the connection body and does not protrude on the other side.