JP7421255B1 - force sensor - Google Patents

Abstract

The strain body includes a first connection portion and a second sensor body side connection portion. The second sensor body side connection part is a pair of pedestals connected to the second sensor body, and includes a pair of pedestals located on both sides of the second end in the second direction, and a pair of pedestals located on both sides of the second end in the second direction. A second connecting portion extending in the second direction from the second end to the one pedestal, and a third connecting portion extending in the second direction from the second end to the other pedestal when viewed in the third direction. There is. The displacement portion extends from the second end in a direction intersecting the second direction when viewed in the first direction. The detection element detects a change in capacitance value based on the displacement of the tip of the displacement section.

Description

The present invention relates to a force sensor.

2. Description of the Related Art Force sensors are known that output a force acting in a predetermined axial direction and a moment (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.

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

Such force sensors are required to have improved detection sensitivity.

JP2021-135103 Publication

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

[1] This disclosure includes:
a first sensor body subjected to the action of a force or moment to be detected;
a second sensor body disposed at a different position from the first sensor body in a first direction;
a strain-generating body that connects the first sensor body and the second sensor body and is elastically deformed by the action of a force or moment received by the first sensor body;
a detection element that detects displacement caused by elastic deformation of the strain body;
a detection circuit that outputs an electric signal indicating a force or moment acting on the first sensor body based on a detection result of the detection element;
Equipped with
A direction perpendicular to the first direction is a second direction, a direction perpendicular to the first direction and perpendicular to the second direction is a third direction,
The strain body includes a first connecting portion extending in the first direction from a first end connected to the first sensor body to a second end located on the opposite side of the first end; a second sensor body side connection part that connects the second end of the first connection part to the second sensor body,
The second sensor body side connection part is a pair of pedestals connected to the second sensor body, and includes a pair of pedestals located on both sides of the second end in the second direction, and a pair of pedestals located on both sides of the second end in the second direction. a second connecting portion extending in the second direction from the second end to one of the pedestals when viewed; and a second connecting portion extending from the second end to the other pedestal when viewed in the third direction; a third connecting portion extending in the direction; and a displacement portion extending from the second end in a direction intersecting the second direction when viewed in the first direction,
The detection element detects a change in capacitance value based on displacement of the tip of the displacement part.
It may also be a force sensor.

[2] This disclosure includes:
The strain body includes a first sensor body side connection part that connects the first end of the first connection part to the first sensor body,
The first sensor body side connection part is a thin part formed along the second direction and the third direction, and includes a thin part connected to the first end of the first connection part.
The force sensor described in [1] may be used.

[3] This disclosure includes:
The detection element includes a fixed electrode substrate provided on the second sensor body, and a displacement electrode substrate provided at the tip of the displacement portion and facing the fixed electrode substrate.
The force sensor described in [1] or [2] may be used.

[4] This disclosure includes:
The fixed electrode substrate includes a first fixed electrode substrate located on one side of the pedestal with respect to the central axis of the flexure-generating body, and a first fixed electrode substrate located on the other side of the pedestal with respect to the central axis of the flexure-generating body. a second fixed electrode substrate,
The force sensor described in [3] may be used.

[5] This disclosure includes:
The displacement electrode substrate includes a first displacement electrode substrate located on one side of the pedestal with respect to the central axis of the strain-generating body, and a first displacement electrode substrate located on the other side of the pedestal with respect to the central axis of the strain-generating body. a second displacement electrode substrate;
The force sensor described in [3] or [4] may be used.

[6] This disclosure includes:
The displacement portion extends in the third direction from the second end of the first connection portion.
The force sensor described in any one of [1] to [5] may be used.

[7] This disclosure includes:
When viewed in the first direction, the second sensor body side connection portion is formed in a straight line along the second direction.
The force sensor described in any one of [1] to [6] may be used.

[8] This disclosure includes:
When viewed in the first direction, the first sensor body and the second sensor body are formed in a circular shape,
When viewed in the first direction, the second sensor body side connection portion is formed in an arc shape along at least one of a peripheral edge of the first sensor body and a peripheral edge of the second sensor body.
The force sensor described in any one of [1] to [7] may be used.

[9] This disclosure includes:
The first sensor body and the second sensor body are connected by the four strain 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 an XYZ three-dimensional coordinate system,
The first strain body is arranged on the positive side in the Y-axis direction with respect to the center of the first sensor body, and the second strain body is arranged on the negative side in the X-axis direction with respect to the center of the first sensor body. The third strain-generating body is arranged on the negative side in the Y-axis direction with respect to the center of the first sensor body, and the fourth strain-generating body is arranged on the positive side in the X-axis direction with respect to the center of the first sensor body. is located,
The force sensor described in any one of [1] to [8] may be used.

[10] The present disclosure includes:
The displacement portion extends from the second end of the corresponding first connection portion toward the center of the first sensor body.
The force sensor described in [9] may be used.

According to the present invention, detection sensitivity can be improved.

FIG. 1 is a perspective view showing an example of a robot to which a force sensor according to the first embodiment is applied. FIG. 2 is a cross-sectional view showing the force sensor according to the first embodiment, and corresponds to a cross-section taken along line AA in FIG. 3, which will be described later. FIG. 3 is a plan view showing the force sensor of FIG. 2 with the force receiving body omitted. FIG. 4 is a front view showing the first strain body of FIG. 2. FIG. FIG. 5 is a plan view showing the first strain body of FIG. 4. FIG. 6 is a side view showing the first strain body of FIG. 4. FIG. FIG. 7 is a plan view of the strain body of the force sensor shown in FIG. 3. As shown in FIG. FIG. 8 is a front view schematically showing a deformed state of the first strain body in FIG. 4 when the first strain body receives a force on the positive side in the X-axis direction. FIG. 9A is a side view schematically showing a deformed state of the first strain body in FIG. 4 when the first strain body receives a force on the positive side in the Y-axis direction. FIG. 9B is a side view schematically showing a deformed state of the first strain body in FIG. 4 when the first strain body receives a force on the negative side in the Y-axis direction. FIG. 10A is a front view schematically showing a deformed state of the first strain body in FIG. 4 when the first strain body receives a force on the positive side in the Z-axis direction. FIG. 10B is a front view schematically showing a deformed state of the first strain body in FIG. 4 when the first strain body receives a force on the negative side in the Z-axis direction. FIG. 11 is a table showing changes in capacitance values of each capacitive element in the strain body of FIG. 4. FIG. FIG. 12 is a table showing changes in the capacitance value of each capacitive element in the force sensor of FIG. FIG. 13 is a front view of a first strain body showing a modification of the detection element of FIG. 4. FIG. FIG. 14 is a plan view showing the force sensor according to the second embodiment, with the force receiving body omitted. FIG. 15 is a front view of the first strain body shown in FIG. 14. FIG. 16 is a plan view showing the first strain body of FIG. 15. FIG. 17 is a side view showing the first strain body of FIG. 15. FIG. 18 is a plan view of a first strain body showing a modification of the detection element shown in FIG. 15. FIG.

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

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

(First embodiment)
A force sensor according to a first embodiment of the present invention will be described using FIGS. 1 to 13.

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

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

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

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

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

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

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

As shown in FIGS. 2 and 3, the force sensor 10 includes a force receiving body 20, a fixed body 25, strain bodies 30A to 30D, a detection element 70, a detection circuit 75, an exterior body 80, It is equipped with Each component will be explained in more detail below. Note that although FIG. 2 is a cross-sectional view taken along the line AA in FIG. 3, it schematically shows the second strain body 30B and the fourth strain body 30D for convenience.

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

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

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

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

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

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

As shown in FIG. 3, the first strain body 30A may be disposed on the positive side in the Y-axis direction with respect to the center O of the force-receiving body 20 when viewed in the Z-axis direction. Similarly, when viewed in the Z-axis direction, the second strain-generating body 30B may be arranged on the negative side in the X-axis direction with respect to the center O of the force receiving body 20. The third strain body 30C may be arranged on the negative side in the Y-axis direction with respect to the center O of the force receiving body 20. The fourth strain body 30D may be arranged on the positive side in the X-axis direction with respect to the center O of the force receiving body 20. In this case, the center O of the force receiving body 20 is arranged between the first strain body 30A and the third strain body 30C, and between the second strain body 30B and the fourth strain body 30D, A center O of the force receiving body 20 is located.

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

As shown in FIG. 3, the four strain-generating bodies 30A to 30D according to this embodiment are arranged in a ring shape. That is, as described above, the force-receiving body 20 and the fixed body 25 are formed in a circular shape when viewed in the Z-axis direction, and the four strain-generating bodies 30A to 30D are arranged to form a rectangular ring shape. has been done. Each strain body 30A to 30D is formed linearly along the second direction when viewed in the Z-axis direction. That is, the second direction of the first strain body 30A and the second direction of the third strain body 30C correspond to the X-axis direction. The first strain body 30A and the third strain body 30C are formed linearly along the X-axis direction. The second direction of the second strain body 30B and the second direction of the fourth strain body 30D correspond to the Y-axis direction. The second strain body 30B and the fourth strain body 30D are formed linearly along the Y-axis direction. Note that the second direction of each strain body 30A to 30D is not limited to the example shown in FIG. 3, and may be any direction. Further, the second direction of each strain body 30A to 30D does not need to be along either the X-axis direction or the Y-axis direction. For example, the arrangement of the four strain bodies 30A to 30D is not limited to an annular arrangement, and each may be arranged irregularly at any position.

Next, the strain bodies 30A to 30D according to this embodiment will be explained in more detail.

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

As shown in FIGS. 2 and 4, the first strain body 30A may include a first connection portion 31 and a fixed body side connection portion 32.

The first connecting portion 31 includes a first end 31a connected to the force receiving body 20, and a second end 31b located on the opposite side of the first end 31a. The first connecting portion 31 extends in the Z-axis direction from the first end 31a to the second end 31b. The first end portion 31a is connected to a surface of a thin portion 40 (described later) on the fixed body 25 side (lower surface in FIG. 4). The second end portion 31b is connected to a displacement portion 36, which will be described later, and is located between the second connection portion 34 and the third connection portion 35. The first connecting portion 31 may be formed linearly along each of the Y-axis direction and the Z-axis direction. As shown in FIG. 4, the first connecting portion 31 may be formed along the central axis CL of the first strain body 30A. The central axis CL of the first strain body 30A is a line along the Z-axis direction passing through the center of the first strain body 30A in the X-axis direction. The first end portion 31a is connected to the force-receiving body 20 via a force-receiving body-side connecting portion 38, which will be described later. The first connecting portion 31 may be elastically deformable by the action of forces in the X-axis direction and the Y-axis direction.

The fixed body side connection part 32 is an example of the second sensor body side connection part. The fixed body side connecting portion 32 connects the second end portion 31b of the first connecting portion 31 to the fixed body 25. The fixed body side connecting portion 32 includes a pair of fixed body side pedestals 33, a second connecting portion 34, a third connecting portion 35, and a displacement portion 36.

The fixed body side pedestal 33 according to this embodiment may be connected to the fixed body 25. The fixed body side pedestal 33 extends in the Z-axis direction from the fixed body 25 toward the force receiving body 20. The fixed body side pedestals 33 are located on both sides of the second end portion 31b of the first connecting portion 31 in the X-axis direction, and on both sides of the central axis CL. One fixed body side pedestal 33 is located on the positive side in the X-axis direction with respect to the second end portion 31b. The other fixed body side pedestal 33 is located on the negative side of the second end 31b in the X-axis direction.

The fixed body side pedestal 33 comes into contact with the fixed body 25 and is attached to the fixed body 25 using bolts or the like (not shown). A screw hole (not shown) may be formed in the surface of the fixed body side pedestal 33 on the side of the fixed body 25 (the lower surface in FIG. 4). The fixed body side pedestal 33 may have one screw hole or a plurality of screw holes formed therein.

The second connecting portion 34 extends in the X-axis direction. The second connecting portion 34 may be formed in a flat plate shape along the X-axis direction and the Y-axis direction. The second connecting portion 34 extends linearly from the second end 31b of the first connecting portion 31 to one of the fixed body side pedestals 33 when viewed in the Y-axis direction. In the example shown in FIG. 4, the second connecting portion 34 is connected to and supported by the fixed body side pedestal 33 located on the positive side in the X-axis direction with respect to the second end portion 31b. The second connecting portion 34 may be elastically deformable by the action of forces in the X-axis direction, the Y-axis direction, and the Z-axis direction.

The third connecting portion 35 extends in the X-axis direction. The third connecting portion 35 may be formed in a flat plate shape along the X-axis direction and the Y-axis direction. The third connecting portion 35 extends linearly from the second end portion 31b of the first connecting portion 31 to the other fixed body side pedestal 33 when viewed in the Y-axis direction. In the example shown in FIG. 4, the third connecting portion 35 is connected to and supported by the fixed body side pedestal 33 located on the negative side of the X-axis direction with respect to the second end portion 31b. The third connecting portion 35 may be elastically deformable by the action of forces in the X-axis direction, the Y-axis direction, and the Z-axis direction.

As shown in FIGS. 4 to 6, the displacement portion 36 extends from the second end portion 31b of the first connecting portion 31 in a direction intersecting the X-axis direction when viewed in the Z-axis direction. The displacement portion 36 may extend in the Y-axis direction from the second end portion 31b, or may be formed linearly along the Y-axis direction. As shown in FIGS. 4 and 6, the displacement portion 36 extends from the surface of the second end portion 31b on the fixed body 25 side. The surface of the second end 31b on the fixed body 25 side is a surface of the second end 31b on the negative side in the Z-axis direction, and corresponds to the lower surface shown in FIG. 4. However, the displacement portion 36 may extend from the Y-axis direction negative side surface (the front surface shown in FIG. 4) of the second end portion 31b.

As shown in FIG. 3, the displacement portion 36 of the first strain body 30A extends from the second end portion 31b of the first connection portion 31 of the first strain body 30A to the force receiving body when viewed in the Z-axis direction. It extends toward the center O of 20. The displacement portion 36 of the first strain body 30A extends from the second end portion 31b toward the negative side in the Y-axis direction. The displacement portion 36 of the first strain body 30A may be located at the center of the first strain body 30A in the X-axis direction, and the center axis CL of the first strain body 30A when viewed in the Y-axis direction. (See FIGS. 4 and 7).

As shown in FIG. 3, the displacement portion 36 of the second strain body 30B extends from the second end portion 31b of the first connection portion 31 of the second strain body 30B to the force receiving body when viewed in the Z-axis direction. It extends toward the center O of 20. The displacement portion 36 of the second strain body 30B extends from the second end portion 31b toward the positive side in the X-axis direction. The displacement portion 36 of the second strain body 30B may be located at the center of the second strain body 30B in the Y-axis direction, and the center axis CL of the second strain body 30B when viewed in the X-axis direction. (See FIGS. 4 and 7).

As shown in FIG. 3, the displacement portion 36 of the third strain-generating body 30C extends from the second end portion 31b of the first connection portion 31 of the third strain-generating body 30C to the force-receiving body when viewed in the Z-axis direction. It extends toward the center O of 20. The displacement portion 36 of the third strain body 30C extends from the second end portion 31b toward the positive side in the Y-axis direction. The displacement portion 36 of the third strain body 30C may be located at the center of the third strain body 30C in the X-axis direction, and the central axis CL of the third strain body 30C when viewed in the Y-axis direction. (See FIGS. 4 and 7).

As shown in FIG. 3, the displacement portion 36 of the fourth strain body 30D extends from the second end portion 31b of the first connection portion 31 of the fourth strain body 30D to the force receiving body when viewed in the Z-axis direction. It extends toward the center O of 20. The displacement portion 36 of the fourth strain body 30D extends from the second end portion 31b toward the negative side in the X-axis direction. The displacement portion 36 of the fourth strain body 30D may be located at the center of the fourth strain body 30D in the Y-axis direction, and the central axis of the fourth strain body 30D when viewed in the X-axis direction. It may overlap with CL (see FIGS. 4 and 7).

As shown in FIGS. 4 to 6, the first strain body 30A may further include a force receiving body side connection portion 38. The force receiving body side connecting portion 38 is an example of the first sensor body side connecting portion. The force receiving body side connecting portion 38 connects the first end portion 31 a of the first connecting portion 31 to the force receiving body 20 . The force receiving body side connecting portion 38 is interposed between the first end portion 31 a of the first connecting portion 31 and the force receiving body 20 . The force-receiving body-side connection portion 38 may include a pair of force-receiving body-side pedestals 39 and a thin wall portion 40 .

The force receiving body side pedestal 39 may be connected to the force receiving body 20. The force-receiving body side pedestal 39 extends in the Z-axis direction from the force-receiving body 20 toward the fixed body 25. The force receiving body side pedestals 39 are located on both sides of the first end 31a of the first connecting portion 31 in the X-axis direction, and on both sides of the central axis CL. One of the force-receiving body side pedestals 39 is located on the positive side in the X-axis direction with respect to the first end portion 31a. The other force-receiving body side pedestal 39 is located on the negative side in the X-axis direction with respect to the first end 31a.

The force-receiving body side pedestal 39 is in contact with the force-receiving body 20 and is attached to the force-receiving body 20 using bolts or the like (not shown). As shown in FIGS. 3 and 5, a screw hole 41 may be formed in the surface of the force receiving body side pedestal 39 on the side of the force receiving body 20 (the upper surface in FIG. 4). One screw hole 41 may be formed in each of the force receiving body side pedestals 39, or a plurality of screw holes 41 may be formed.

The thin portion 40 is located between the pair of force-receiving body-side pedestals 39 and is connected to each force-receiving body-side pedestal 39 . The thin wall portion 40 connects the force receiving body side pedestal 39 and the first connecting portion 31 . The first end portion 31a of the first connecting portion 31 is connected to the surface of the thin portion 40 on the fixed body 25 side (the lower surface in FIG. 4). The thin portion 40 extends in the X-axis direction. The thin portion 40 may be formed in a flat plate shape along the X-axis direction and the Y-axis direction. As shown in FIG. 4, the thickness t1 (dimension in the Z-axis direction) of the thin wall portion 40 is thinner than the thickness t2 (dimension in the Z-axis direction) of the force-receiving body side pedestal 39. The thin portion 40 may be elastically deformable by the action of forces in the X-axis direction, the Y-axis direction, and the Z-axis direction.

The thin portion 40 is connected to a portion of the force receiving body side pedestal 39 on the fixed body 25 side. As a result, a first recess 42 is formed on the force receiving body 20 side of the thin wall portion 40 . As shown in FIG. 4, the first recess 42 may be formed in a rectangular shape when viewed in the Y-axis direction. When the thin wall portion 40 and the first connecting portion 31 are formed separately, the head of a bolt (not shown) for fixing the thin wall portion 40 and the first connecting portion 31 is arranged in the first recess 42. can do. Thereby, the head of the bolt can be prevented from protruding from the force-receiving body side connection part 38, and the height of the force sensor 10 can be reduced.

As shown in FIGS. 4 and 5, the fixed body side connecting portion 32 described above may be formed linearly along the X-axis direction when viewed in the Z-axis direction. Similarly, the force-receiving body side connecting portion 38 described above may be formed linearly along the X-axis direction. When viewed in the Z-axis direction, as shown in FIG. 5, the force-receiving body side connection portion 38 may overlap the fixed body side connection portion 32.

The first strain body 30A configured as described above may be integrally formed of a continuous material. The first strain body 30A may be produced by machining (for example, cutting) from one block material, or may be produced by casting. The first strain body 30A may be made of a metal material such as an aluminum alloy or an iron alloy.

The detection element 70 is configured to detect the displacement caused by the elastic deformation of the first strain body 30A described above. The detection element 70 according to the present embodiment is configured as an element that detects a change in capacitance value based on the displacement of the tip portion 36a of the displacement portion 36 described above.

As shown in FIGS. 4 and 5, the detection element 70 includes a first capacitive element C1 and a second capacitive element C2. The first capacitive element C1 and the second capacitive element C2 each detect a change in capacitance value based on the displacement of the tip 36a of the displacement part 36 of the first strain body 30A. The first capacitive element C1 and the second capacitive element C2 are capacitive elements for the first strain body 30A shown in FIG.

In the example shown in FIGS. 4 and 5, the first capacitive element C1 includes a first fixed electrode substrate Ef1 provided on the fixed body 25 and a first displacement electrode substrate Ed1 provided on the tip 36a of the displacement section 36. Contains. The second capacitive element C2 includes a second fixed electrode substrate Ef2 provided on the fixed body 25 and a second displacement electrode substrate Ed2 provided on the distal end portion 36a of the displacement portion 36. The first capacitive element C1 is arranged on the positive side in the X-axis direction with respect to the central axis CL of the first strain body 30A. The second capacitive element C2 is arranged on the negative side in the X-axis direction with respect to the central axis CL of the first flexural body 30A.

As shown in FIG. 4, the first fixed electrode substrate Ef1 is located on the side of one fixed body side pedestal 33 with respect to the central axis CL of the first strain body 30A. More specifically, the first fixed electrode substrate Ef1 is located on the positive side in the X-axis direction with respect to the central axis CL of the first strain body 30A. The second fixed electrode substrate Ef2 is located on the side of the other fixed body side pedestal 33 with respect to the central axis CL of the first strain body 30A. The second fixed electrode substrate Ef2 is located on the negative side in the X-axis direction with respect to the central axis CL of the first flexure element 30A.

As shown in FIGS. 4 to 6, the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 may be integrated. More specifically, the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 each include a fixed electrode Ef (see FIG. 13) and an insulator. The insulator is interposed between the fixed electrode Ef and the fixed body 25. The fixed electrode Ef of the first fixed electrode substrate Ef1 and the fixed electrode Ef of the second fixed electrode substrate Ef2 are integrated to form a common fixed electrode Efc. The insulator of the first fixed electrode substrate Ef1 and the insulator of the second fixed electrode substrate Ef2 are integrated to form a common insulator IBfc. The common insulator IBfc may be joined to the fixed body 25 with an adhesive or the like, or may be fixed with a bolt or the like. The entire common insulator IBfc may be joined to the fixed body 25.

As shown in FIGS. 4 and 5, the first displacement electrode substrate Ed1 is located on the side of one fixed body side pedestal 33 with respect to the central axis CL of the first strain body 30A. More specifically, the first displacement electrode substrate Ed1 is located on the positive side in the X-axis direction with respect to the central axis CL of the first strain body 30A, and is opposed to the first fixed electrode substrate Ef1 described above. There is. The second displacement electrode substrate Ed2 is located on the side of the other fixed body side pedestal 33. More specifically, the second displacement electrode substrate Ed2 is located on the negative side in the X-axis direction with respect to the central axis CL of the first flexure element 30A, and is opposed to the second fixed electrode substrate Ef2 described above. There is.

The first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 each include a displacement electrode Ed and an insulator. The displacement electrode Ed of the first displacement electrode substrate Ed1 faces the fixed electrode Ef of the first fixed electrode substrate Ef1, and the displacement electrode Ed of the second displacement electrode substrate Ed2 faces the fixed electrode Ef of the second fixed electrode substrate Ef2. are doing. The displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 may be formed separately and spaced apart from each other. The insulator is interposed between the displacement electrode Ed and the displacement section 36. The insulator of the first displacement electrode substrate Ed1 and the insulator of the second displacement electrode substrate Ed2 may be integrated to form a common insulator IBdc. The common insulator IBdc may be joined to the displacement portion 36 with an adhesive or the like, or may be fixed with a bolt or the like. A portion of the common insulator IBdc may be joined to the displacement portion 36.

The first capacitive element C1 and the second capacitive element C2 are arranged at the same position in the Y-axis direction. That is, as shown in FIGS. 3, 5, and 6, the displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 are arranged at the same position in the Y-axis direction. The first capacitive element C1 and the second capacitive element C2 are arranged on the negative side in the Y-axis direction with respect to the first connecting portion 31.

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

When viewed in the Z-axis direction, the planar shape of the displacement electrode Ed of the first displacement electrode substrate Ed1 may be smaller than the planar shape of the common fixed electrode Efc. Even if the force receiving body 20 receives a force or moment and the first displacement electrode substrate Ed1 is displaced, the displacement electrodes Ed of the first displacement electrode substrate Ed1 are common as a whole when viewed in the Z-axis direction. The size of the displacement electrode Ed and the size of the common fixed electrode Efc may be set so as to overlap the fixed electrode Efc. Thereby, it is possible to prevent the opposing area between the displacement electrode Ed and the common fixed electrode Efc from changing, and it is possible to prevent the change in the opposing area from affecting a change in the capacitance value. Therefore, the capacitance value can be changed according to a change in the distance between the displacement electrode Ed and the common fixed electrode Efc. Here, the opposing area refers to the area where the displacement electrode Ed and the common fixed electrode Efc overlap when viewed in the Z-axis direction. When the displacement portion 36 is tilted, the displacement electrode Ed, which is smaller than the common fixed electrode Efc, may be tilted and the opposing area may vary, but the tilt angle of the displacement electrode Ed in this case is small. As a result, the change in capacitance value is dominated by the distance between the displacement electrode Ed and the common fixed electrode Efc. Therefore, in this specification, changes in the facing area due to the inclination of the displacement electrode Ed are not considered, and changes in the capacitance value are considered to be caused by changes in the distance between the displacement electrode Ed and the common fixed electrode Efc. In addition, in FIG. 8 etc. which will be described later, the inclination of the displacement portion 36 is exaggerated in order to make the drawings clear.

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

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

The insulator may be made of an insulating material such as glass epoxy resin or ceramic. Alternatively, the fixed electrode substrates Ef1 and Ef2 may be composed of FPC boards (flexible printed circuit boards). The FPC board is a flexible printed circuit board that is formed into a thin film shape. In the FPC board, a metal thin film constituting electrodes and wiring is formed on the upper surface of a polyimide film. Portions of the FPC board corresponding to the fixed electrode boards Ef1 and Ef2 may be fixed to the fixed body 25. The FPC board may include wiring that connects the fixed electrode Ef to the detection circuit 75. When the insulator is composed of an FPC board, portions corresponding to the displacement electrode substrates Ed1 and Ed2 may be fixed to the displacement portion 36. The FPC board may include wiring that connects the displacement electrode Ed to the detection circuit 75.

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

That is, as shown in FIG. 3, the detection element 70 further includes a third capacitive element C3 and a fourth capacitive element C4. The third capacitive element C3 and the fourth capacitive element C4 each detect a change in capacitance value based on the displacement of the tip end 36a of the displacement part 36 of the second strain body 30B. The third capacitive element C3 and the fourth capacitive element C4 are capacitive elements for the second strain body 30B.

As shown in FIG. 7, the third capacitive element C3 includes a third fixed electrode substrate Ef3 provided on the fixed body 25 and a third displacement electrode substrate Ed3 provided on the tip 36a of the displacement section 36. I'm here. The fourth capacitive element C4 includes a fourth fixed electrode substrate Ef4 provided on the fixed body 25 and a fourth displacement electrode substrate Ed4 provided on the tip portion 36a of the displacement portion 36.

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

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

The third capacitive element C3 and the fourth capacitive element C4 are arranged at the same position in the X-axis direction. That is, as shown in FIG. 3, the displacement electrode Ed of the third displacement electrode substrate Ed3 and the displacement electrode Ed of the fourth displacement electrode substrate Ed4 are arranged at the same position in the X-axis direction. The third capacitive element C3 and the fourth capacitive element C4 are arranged on the positive side in the X-axis direction with respect to the first connecting portion 31.

Further, as shown in FIG. 3, the detection element 70 further includes a fifth capacitive element C5 and a sixth capacitive element C6. The fifth capacitive element C5 and the sixth capacitive element C6 each detect a change in capacitance value based on the displacement of the distal end portion 36a of the displacement portion 36 of the third strain body 30C. The fifth capacitive element C5 and the sixth capacitive element C6 are capacitive elements for the third strain body 30C.

As shown in FIG. 7, the fifth capacitive element C5 includes a fifth fixed electrode substrate Ef5 provided on the fixed body 25 and a fifth displacement electrode substrate Ed5 provided on the tip portion 36a of the displacement portion 36. I'm here. The sixth capacitive element C6 includes a sixth fixed electrode substrate Ef6 provided on the fixed body 25 and a sixth displacement electrode substrate Ed6 provided on the tip portion 36a of the displacement portion 36.

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

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

The fifth capacitive element C5 and the sixth capacitive element C6 are arranged at the same position in the Y-axis direction. That is, as shown in FIG. 3, the displacement electrodes Ed of the fifth displacement electrode substrate Ed5 and the displacement electrodes Ed of the sixth displacement electrode substrate Ed6 are arranged at the same position in the Y-axis direction. The fifth capacitive element C5 and the sixth capacitive element C6 are arranged on the positive side in the Y-axis direction with respect to the first connecting portion 31.

Further, as shown in FIG. 3, the detection element 70 further includes a seventh capacitive element C7 and an eighth capacitive element C8. The seventh capacitive element C7 and the eighth capacitive element C8 each detect a change in capacitance value based on the displacement of the tip end 36a of the displacement part 36 of the fourth strain body 30D. The seventh capacitive element C7 and the eighth capacitive element C8 are capacitive elements for the fourth strain body 30D.

As shown in FIG. 7, the seventh capacitive element C7 includes a seventh fixed electrode substrate Ef7 provided on the fixed body 25 and a seventh displacement electrode substrate Ed7 provided on the tip 36a of the displacement section 36. I'm here. The eighth capacitive element C8 includes an eighth fixed electrode substrate Ef8 provided on the fixed body 25 and an eighth displacement electrode substrate Ed8 provided on the tip portion 36a of the displacement portion 36.

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

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

The seventh capacitive element C7 and the eighth capacitive element C8 are arranged at the same position in the X-axis direction. That is, as shown in FIG. 3, the displacement electrodes Ed of the seventh displacement electrode substrate Ed7 and the displacement electrodes Ed of the eighth displacement electrode substrate Ed8 are arranged at the same position in the X-axis direction. The seventh capacitive element C7 and the eighth capacitive element C8 are arranged on the negative side in the X-axis direction with respect to the first connecting portion 31.

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

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

Next, a method of detecting force or moment when force or moment acts on the force sensor 10 according to the present embodiment having such a configuration will be described with reference to FIGS. 8 to 10B. 8 is a front view schematically showing a deformed state of the first strain body 30A when the first strain body 30A in FIG. 4 receives a force Fx on the positive side in the X-axis direction, and FIG. 4 is a side view schematically showing a deformed state of the first strain body 30A when the first strain body 4 receives a force Fy on the positive side in the Y-axis direction. FIG. FIG. 9B is a side view schematically showing a deformed state of the first strain body 30A when the first strain body 30A in FIG. 4 receives a force Fy on the negative side in the Y-axis direction. FIG. 10A is a front view schematically showing a deformed state of the first strain body 30A in FIG. 4 when the first strain body 30A in FIG. 4 receives a force Fz on the positive side in the Z-axis direction. FIG. 10B is a front view schematically showing a deformed state of the first strain body 30A in FIG. 4 when the first strain body 30A receives a force on the negative side in the Z-axis direction.

When the force receiving body 20 is subjected to a force or moment, the force or moment is transmitted to the first strain body 30A to the fourth strain body 30D. More specifically, the force or moment is transmitted to the thin wall portion 40, the first connecting portion 31, the second connecting portion 34, and the third connecting portion 35, and the thin wall portion 40 and each of the connecting portions 31, 34, and 35 are elastically deformed. occurs. This causes displacement in the displacement portion 36. Therefore, the distance between each fixed electrode substrate Ef1 to Ef8 of the detection element 70 and the corresponding displacement electrode substrate Ed1 to Ed8 changes, and the capacitance value of each capacitive element C1 to C8 changes. This change in capacitance value is detected by the detection element 70 as a displacement occurring in the strain-generating bodies 30A to 30D. In this case, the capacitance values of the capacitive elements C1 to C8 may change differently. Therefore, the detection circuit 75 detects the direction and magnitude of the force or moment acting on the force receiving body 20 based on the change in the capacitance value of each capacitive element C1 to C8 detected by the detection element 70. be able to.

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

(When +Fx works)
When the force Fx acts on the first strain body 30A in the positive direction of the X-axis, as shown in FIG. 34 and the third connecting portion 35 are elastically deformed, the first end portion 31a of the first connecting portion 31 is displaced toward the positive side in the X-axis direction. As a result, the first connecting portion 31 is tilted toward the positive side in the X-axis direction. In other words, the first connecting portion 31 rotates clockwise when viewed toward the positive side in the Y-axis direction (when viewed toward the page of FIG. 8). In conjunction with the first connecting portion 31, the displacement portion 36 rotates clockwise and tilts.

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

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

(When +Fy acts)
When force Fy is applied to the first strain body 30A in the positive direction of the Y-axis, as shown in FIG. While being elastically deformed, the first end portion 31a of the first connecting portion 31 is displaced toward the positive side in the Y-axis direction. As a result, the first connecting portion 31 is tilted toward the positive side in the Y-axis direction. In other words, the first connecting portion 31 rotates counterclockwise when viewed toward the positive side in the X-axis direction (when viewed toward the page of FIG. 9A). In conjunction with the first connecting part 31, the displacement part 36 rotates counterclockwise and tilts. In this case, the distal end portion 36a of the displacement portion 36 is displaced in the direction away from the fixed body 25.

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

(When -Fy acts)
When the force Fy acts on the first strain body 30A in the negative side of the Y-axis direction, as shown in FIG. 9B, a phenomenon opposite to that shown in FIG. 9A occurs.

When force Fy is applied to the first strain body 30A in the Y-axis direction negative side, as shown in FIG. 9B, the thin portion 40, the first connecting portion 31, the second connecting portion 34, and the third connecting portion While being elastically deformed, the first end portion 31a of the first connecting portion 31 is displaced to the negative side in the Y-axis direction. As a result, the first connecting portion 31 is tilted toward the negative side in the Y-axis direction. In other words, the first connecting portion 31 rotates clockwise when viewed toward the positive side in the X-axis direction (when viewed toward the page of FIG. 9B). In conjunction with the first connecting part 31, the displacement part 36 rotates clockwise and tilts. In this case, the distal end portion 36a of the displacement portion 36 is displaced in a direction approaching the fixed body 25.

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

(When +Fz acts)
When force Fz is applied to the first strain body 30A in the positive direction of the Z-axis, as shown in FIG. The first connecting portion 31 is displaced to the positive side in the Z-axis direction. In conjunction with the first connecting portion 31, the displacement portion 36 is displaced toward the positive side in the Z-axis direction.

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

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

When force Fz is applied to the first strain body 30A in the negative direction in the Z-axis direction, as shown in FIG. The first connecting portion 31 is displaced to the negative side in the Z-axis direction. In conjunction with the first connecting portion 31, the displacement portion 36 is displaced toward the negative side in the Z-axis direction.

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

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

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

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

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

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

The displacement portion 36 of the first strain body 30A shown in FIG. 4 extends from the second end portion 31b of the first connecting portion 31 toward the negative side in the Y-axis direction. The first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 are located at the tip portion 36a of the displacement portion 36. With this, it is possible to increase the displacement of the tip portion 36a of the displacement portion 36 when the force Fy is applied, and it is possible to increase the change in the capacitance value. Therefore, the detection sensitivity of the force Fy can be increased. For example, by adjusting the length of the displacement section 36, the detection sensitivity of the force Fy can be adjusted. The detection sensitivity of force Fy may be higher than the detection sensitivity of force Fx and the detection sensitivity of force Fz.

For example, the center position (PY shown in FIGS. 5 and 6) of the displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 in the Y-axis direction is It may be located on the negative side of the connecting portion 35 in the Y-axis direction. This allows the capacitance values of the first capacitive element C1 and the second capacitive element C2 to be changed when the force Fy is applied. In this case, when viewed in the Z-axis direction, a portion of the first displacement electrode substrate Ed1 may overlap the second connection portion 34, and a portion of the second displacement electrode substrate Ed2 may overlap the third connection portion 35. They may overlap.

For example, the displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 may be spaced apart from the second connection part 34 and the third connection part 35 in the Y-axis direction. This allows the capacitance values of the first capacitive element C1 and the second capacitive element C2 to be further changed when the force Fy is applied.

On the other hand, the length of the displacement portion 36 of the displacement electrode substrates Ed1 and Ed2 may be set so as not to interfere with the other displacement electrode substrates Ed3 to Ed8.

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

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

In this case, the first flexural body 30A is elastically deformed in the same way as the first flexural body 30A shown in FIG. Capacitance value decreases.

The second strain body 30B is elastically deformed in the same manner as the first strain body 30A shown in FIG. 9B, and the capacitance value of the third capacitance element C3 increases and the capacitance value of the fourth capacitance element C4 increases. increase As described above, since the displacement portion 36 of the second strain body 30B extends from the second end 31b of the first connection portion 31 in the positive direction of the X-axis, the capacitance value of the third capacitance element C3 decreases. The amount of increase is relatively large. Therefore, C3 in the Fx row in the table shown in FIG. 12 is set to "++". Since the amount of increase in the capacitance value of the fourth capacitive element C4 is also relatively large, C4 in the Fx row in the table shown in FIG. 12 is set to "++".

The third strain body 30C is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases.

The fourth strain body 30D is elastically deformed in the same way as the first strain body 30A shown in FIG. 9A, and the capacitance value of the seventh capacitive element C7 decreases while the capacitance value of the eighth capacitive element C8 decreases. Decrease. As described above, since the displacement portion 36 of the fourth strain body 30D extends from the second end portion 31b of the first connection portion 31 toward the negative side in the X-axis direction, the capacitance value of the seventh capacitance element C7 decreases. The amount of increase is relatively large. Therefore, C7 in the Fx row in the table shown in FIG. 12 is set to "--". Since the amount of decrease in the capacitance value of the eighth capacitive element C8 is also relatively large, C8 in the Fx row in the table shown in FIG. 12 is set as "--".

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

The first flexural body 30A is elastically deformed similarly to the first flexural body 30A shown in FIG. 9A, and the capacitance value of the first capacitive element C1 decreases and the capacitance value of the second capacitive element C2 increases. Decrease. Since the displacement portion 36 of the first strain body 30A extends from the second end portion 31b of the first connecting portion 31 toward the negative side in the Y-axis direction, the amount of increase in the capacitance value of the first capacitive element C1 is relatively large. big. Therefore, C1 in the Fy row in the table shown in FIG. 12 is set to "--". Since the amount of increase in the capacitance value of the second capacitive element C2 is also relatively large, C2 in the Fy row in the table shown in FIG. 12 is set as "--".

The second strain body 30B is elastically deformed in the same way as the first strain body 30A shown in FIG. Decrease.

The third flexural body 30C is elastically deformed similarly to the first flexural body 30A shown in FIG. 9B, and the capacitance value of the fifth capacitive element C5 increases and the capacitance value of the sixth capacitive element C6 increases. increase Since the displacement portion 36 of the third strain body 30C extends from the second end 31b of the first connection portion 31 to the positive side in the Y-axis direction, the amount of increase in the capacitance value of the fifth capacitance element C5 is relatively large. big. Therefore, C5 in the Fy row in the table shown in FIG. 12 is set to "++". Since the amount of increase in the capacitance value of the sixth capacitive element C6 is also relatively large, C6 in the Fy row in the table shown in FIG. 12 is set as "++".

The fourth strain body 30D is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases.

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

In this case, the first flexural body 30A is elastically deformed in the same manner as the first flexural body 30A shown in FIG. Capacitance value decreases. Similarly, the third to eighth capacitive elements C3 to C8 also decrease.

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

In this case, the first strain body 30A is elastically deformed in the same manner as the first strain body 30A on which the force Fz directed toward the positive side in the Z-axis direction acts, as shown in FIG. 10A, and the electrostatic charge of the first capacitive element C1 is As the capacitance value decreases, the capacitance value of the second capacitive element C2 also decreases.

In the second strain body 30B, since the central axis CL is located at the center O of the force receiving body 20 in the Y-axis direction, the elastic deformation of the second strain body 30B is similar to that of the first strain body 30A. It is smaller than the third strain body 30C. Here, in order to simplify the explanation, it is assumed that the second strain body 30B is not elastically deformed. 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. C3 and C4 in the Mx row in the table shown in FIG. 12 are set to "0 (zero)".

As shown in FIG. 10B, the third strain body 30C is elastically deformed in the same manner as the first strain body 30A to which the force Fz directed toward the negative side in the Z-axis direction is applied, and the capacitance value of the fifth capacitive element C5 is As the capacitance increases, the capacitance value of the sixth capacitive element C6 also increases.

In the fourth strain body 30D, since the central axis CL is located at the center O of the force receiving body 20 in the Y-axis direction, the elastic deformation of the fourth strain body 30D is similar to that of the first strain body 30A. It is smaller than the third strain body 30C. Here, in order to simplify the explanation, it is assumed that the fourth strain body 30D is not elastically deformed. 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. C7 and C8 in the Mx row in the table shown in FIG. 12 are set to "0 (zero)".

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

In this case, in the first strain body 30A, since the center axis CL is located at the center O of the force receiving body 20 in the X-axis direction, the elastic deformation of the first strain body 30A is caused by the second strain body 30A. It is smaller than the body 30B and the fourth strain body 30D. Here, in order to simplify the explanation, it is assumed that the first strain body 30A is not elastically deformed. 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. C1 and C2 in the My row in the table shown in FIG. 12 are set to "0 (zero)".

As shown in FIG. 10A, the second strain body 30B is elastically deformed in the same manner as the first strain body 30A to which the force Fz directed toward the positive side in the Z-axis direction is applied, and the capacitance value of the third capacitive element C3 is Along with this decrease, the capacitance value of the fourth capacitive element C4 also decreases.

In the third strain body 30C, the central axis CL is located at the center O of the force receiving body 20 in the X-axis direction, so that the elastic deformation of the third strain body 30C is similar to that of the second strain body 30B. It is smaller than the fourth strain body 30D. Here, in order to simplify the explanation, it is assumed that the third strain body 30C is not elastically deformed. 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. C5 and C6 in the My row in the table shown in FIG. 12 are set to "0 (zero)".

As shown in FIG. 10B, the fourth strain body 30D is elastically deformed in the same manner as the first strain body 30A to which the force Fz directed toward the negative side in the Z-axis direction is applied, and the capacitance value of the seventh capacitive element C7 is As the capacitance increases, the capacitance value of the eighth capacitive element C8 also increases.

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

In this case, the first flexural body 30A is elastically deformed in the opposite direction to the first flexural body 30A shown in FIG. The capacitance value increases.

The second strain body 30B is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases.

The third strain body 30C is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases.

The fourth strain body 30D is elastically deformed in the opposite direction to the first strain body 30A shown in FIG. The value increases.

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

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

As described above, the force sensor 10 shown in FIG. This makes it possible to detect six-axis components of force. However, the number of axial components of force that can be detected by the force sensor 10 is not limited to six, and the number of axial components that can be detected is arbitrary depending on the number, structure, and shape of the strain body. It is. The coefficients a1 to a32 included in equations (4) to (9) above are coefficients indicating that the amount of change (increase or decrease) in the capacitance value is relatively small. Coefficients a1 to a32 may be different from each other.

Since the coefficients a1 to a32 are included in the above-described equations (4) to (9), other axis sensitivity occurs in each axis component. However, even when other-axis sensitivity occurs, correction calculation can be performed by finding the inverse matrix of the other-axis sensitivity matrix and multiplying the output (characteristic matrix) of the force sensor by this inverse matrix. As a result, the other axis sensitivity can be reduced, and the other axis sensitivity can be reduced to such an extent that the occurrence of the other axis sensitivity can be ignored.

As described above, the displacement portion 36 of each strain body 30A to 30D extends from the second end portion 31b of the corresponding first connection portion 31 in the X-axis direction or the Y-axis direction. Each of the displacement electrode substrates Ed1 to Ed8 is located at the tip portion 36a of the corresponding displacement portion 36. This allows the displacement of the distal end portion 36a of the displacement portion 36 in the Z-axis direction to be increased when force or moment is applied to the force receiving body 20. Therefore, the change in capacitance value can be increased, and detection sensitivity can be increased. In particular, as shown in FIG. 12, when the force Fx acts on the force receiving body 20, the capacitance values of the third capacitive element C3, the fourth capacitive element C4, the seventh capacitive element C7, and the eighth capacitive element C8 change. The change in force Fx can be increased, and the detection sensitivity of force Fx can be increased. Similarly, when the force Fy acts on the force receiving body 20, the change in the capacitance value of the first capacitive element C1, the second capacitive element C2, the fifth capacitive element C5, and the sixth capacitive element C6 is increased. This makes it possible to increase the detection sensitivity of force Fy.

As described above, according to the present embodiment, the displacement portion 36 of the first strain body 30A moves toward the second end of the first connecting portion 31 in a direction intersecting the X-axis direction when viewed in the Z-axis direction. 31b. The detection element 70 detects a change in capacitance value based on the displacement of the tip portion 36a of the displacement portion 36. Thereby, when the force Fy is applied, the displacement of the distal end portion 36a of the displacement portion 36 in the Z-axis direction can be increased. Therefore, the change in capacitance value can be increased, and the detection sensitivity of the force sensor 10 can be improved.

Further, according to the present embodiment, the first strain body 30A includes the force receiving body side connecting portion 38 that connects the first end portion 31a of the first connecting portion 31 to the force receiving body 20, and The body side connecting portion 38 includes a thin wall portion 40 . The thin portion 40 is formed along the X-axis direction and the Y-axis direction, and is connected to the first connecting portion 31 . As a result, the thin portion 40 can be elastically deformed when force or moment is applied to the force receiving body 20, and the displacement of the distal end portion 36a of the displacement portion 36 in the Z-axis direction can be further increased. can. Therefore, the detection sensitivity of the force sensor 10 can be further improved.

Further, according to the present embodiment, the detection element 70 faces the fixed electrode substrates Ef1 and Ef2 provided on the fixed body 25 and the fixed electrode substrates Ef1 and Ef2 provided on the tip portion 36a of the displacement section 36. It includes displacement electrode substrates Ed1 and Ed2. Thereby, the detection element 70 can detect a change in the capacitance value based on the displacement of the tip portion 36a of the displacement portion 36. Therefore, it is possible to obtain the force sensor 10 with improved detection sensitivity.

Further, according to the present embodiment, the fixed electrode substrates Ef1 and Ef2 include a first fixed electrode substrate Ef1 located on one side of the fixed body side pedestal 33 with respect to the central axis CL of the first strain body 30A; The second fixed electrode substrate Ef2 is located on the side of the other fixed body side pedestal 33 with respect to the central axis CL of the first strain body 30A. As a result, when force Fx in the X-axis direction is applied, it is possible to increase either the capacitance value of the first capacitive element C1 or the capacitance value of the second capacitive element C2, while decreasing the other. can be done. Therefore, the output value when the force Fx is applied can be calculated from the difference between the amount of change in the capacitance value of the first capacitive element C1 and the amount of change in the capacitance value of the second capacitive element C2. In this case, the influence of the above-mentioned disturbance can be offset. Therefore, the output value of the force Fx can be prevented from being influenced by disturbances, and the performance of the force sensor 10 can be improved. Furthermore, when the force-receiving body 20 and the fixed body 25 are connected by four strain-generating bodies 30A to 30D as shown in FIG. 7, the number of detectable axial components can be increased, and six axial components can be detected. be able to.

Further, according to the present embodiment, the displacement electrode substrates Ed1 and Ed2 include the first displacement electrode substrate Ed1 located on the one fixed body side pedestal 33 side with respect to the central axis CL of the first strain body 30A; It includes a second displacement electrode substrate Ed2 located on the other fixed body side pedestal 33 side with respect to the central axis CL of the first strain body 30A. As a result, when force Fx in the X-axis direction is applied, it is possible to increase either the capacitance value of the first capacitive element C1 or the capacitance value of the second capacitive element C2, while decreasing the other. can be done. Therefore, the output value when the force Fx is applied can be calculated from the difference between the amount of change in the capacitance value of the first capacitive element C1 and the amount of change in the capacitance value of the second capacitive element C2. In this case, the influence of the above-mentioned disturbance can be offset. Therefore, the output value of the force Fx can be prevented from being influenced by disturbances, and the performance of the force sensor 10 can be improved. Furthermore, when the force-receiving body 20 and the fixed body 25 are connected by four strain-generating bodies 30A to 30D as shown in FIG. 7, the number of detectable axial components can be increased, and six axial components can be detected. be able to.

Further, according to the present embodiment, the displacement portion 36 of the first strain body 30A extends in the Y-axis direction from the second end portion 31b of the first connection portion 31 of the first strain body 30A. Thereby, when the force Fy in the Y-axis direction is applied to the force-receiving body 20, the displacement of the distal end portion 36a of the displacement portion 36 in the Z-axis direction can be further increased. Therefore, the detection sensitivity of the force Fy can be further improved, and the detection sensitivity of the force sensor 10 can be further improved.

Further, according to the present embodiment, when viewed in the Z-axis direction, the second connecting portion 34 and the third connecting portion 35 are formed linearly along the X-axis direction. Thereby, the first strain body 30A can be manufactured easily, and the cost of the force sensor 10 can be reduced. For example, when the first strain body 30A is manufactured by machining from one block material, the first strain body 30A can be manufactured efficiently, which effectively contributes to cost reduction of the force sensor 10. be able to.

Further, according to the present embodiment, the first strain body 30A is arranged on the positive side in the Y-axis direction with respect to the center O of the force receiving body 20, and the second strain body 30B is arranged on the negative side in the X-axis direction. The third strain body 30C is disposed on the negative side in the Y-axis direction, and the fourth strain body 30D is disposed on the positive side in the X-axis direction. As a result, when viewed in the Z-axis direction, the first strain body 30A to the fourth strain body 30D can be arranged in an annular shape with respect to the center O of the force receiving body 20. Therefore, the accuracy of detecting force or moment in any direction can be improved, and the accuracy of detecting force or moment can be prevented from decreasing depending on the direction of force or moment.

Further, according to the present embodiment, the displacement portion 36 of each strain body 30A to 30D extends from the second end portion 31b of the corresponding first connection portion 31 toward the center of the force receiving body 20. . This makes it possible to improve the space efficiency of each strain body 30A to 30D, and to downsize the force sensor 10.

(Modification 1)
Note that in the present embodiment described above, the displacement portion 36 of the first strain body 30A extends in the Y-axis direction from the second end portion 31b of the first connection portion 31 of the first strain body 30A. explained. However, this embodiment is not limited to this. For example, the displacement portion 36 may extend in a direction other than the Y-axis direction orthogonal to the X-axis direction as long as it intersects the X-axis direction. For example, the displacement portion 36 may extend in a direction inclined to the X-axis direction when viewed in the Z-axis direction. Also in this case, when the force Fy is applied, the displacement of the distal end portion 36a of the displacement portion 36 in the Z-axis direction can be increased.

(Modification 2)
Furthermore, in the present embodiment described above, an example has been described in which the fixed electrode Ef of the first fixed electrode substrate Ef1 and the fixed electrode Ef of the second fixed electrode substrate Ef2 are integrated to form the common fixed electrode Efc. . However, this embodiment is not limited to this. For example, as shown in FIG. 13, the fixed electrode Ef of the first fixed electrode substrate Ef1 and the fixed electrode Ef of the second fixed electrode substrate Ef2 may be formed separately and spaced apart from each other. In this case, the displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 may be integrated to form a common displacement electrode Edc. The planar shape of the fixed electrode Ef of the fixed electrode substrates Ef1 and Ef2 may be smaller than the planar shape of the common displacement electrode Edc. The same applies to the third to eighth fixed electrode substrates Ef3 to Ef8 and the third to eighth displacement electrode substrates Ed3 to Ed8. FIG. 13 is a front view of a first strain body 30A showing a modification of the detection element shown in FIG. 4. FIG.

In the example shown in FIG. 13, the insulator of the first fixed electrode substrate Ef1 and the insulator of the second fixed electrode substrate Ef2 may be integrated to form a common insulator IBfc. However, the insulator of the first fixed electrode substrate Ef1 and the insulator of the second fixed electrode substrate Ef2 may be formed separately and spaced apart from each other. The same applies to the third fixed electrode substrate Ef3 to the eighth fixed electrode substrate Ef8.

(Second embodiment)
Next, a force sensor according to a second embodiment of the present invention will be described using FIGS. 14 to 18.

The second embodiment shown in FIGS. 14 to 18 differs mainly in that the fixed body side connection portion is formed in an arc shape when viewed in the Z-axis direction. The other configurations are substantially the same as the first embodiment shown in FIGS. 1 to 13. Note that in FIGS. 14 to 18, the same parts as in the first embodiment shown in FIGS. 1 to 13 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 14 is a plan view showing the force sensor according to the second embodiment, with the force receiving body omitted. FIG. 15 is a front view of the first strain body shown in FIG. 14. FIG. 16 is a plan view showing the first strain body of FIG. 15. FIG. 17 is a side view showing the first strain body of FIG. 15. FIG. 18 is a plan view of a first strain body showing a modification of the detection element shown in FIG. 15. FIG.

As shown in FIG. 14, the first strain body 30A according to the present embodiment is formed in an arc shape when viewed in the Z-axis direction. As shown in FIGS. 14 to 17, the displacement portion 36 extends from the second end 31b of the first connection portion 31 toward the inside of the second connection portion 34 and the third connection portion 35, that is, toward the inside in the radial direction. ing.

Similar to the force receiving body 20 shown in FIG. 3, the planar shape of the force receiving body 20 shown in FIG. 14 is also circular. Similarly, the planar shape of the fixed body 25 is also circular. The fixed body side connecting portion 32 of the first strain body 30A may be formed in an arc shape along at least one of the periphery of the force receiving body 20 and the periphery of the fixed body 25 when viewed in the Z-axis direction. good. In this embodiment, the fixed body side pedestal 33, the second connecting portion 34, and the third connecting portion 35 are formed in an arc shape along both the periphery of the force receiving body 20 and the periphery of the fixed body 25. . The fixed body side connecting portion 32 of the first strain body 30A is formed concentrically with the outer edge of the force receiving body 20.

As shown in FIGS. 14 and 16, the force-receiving body side connecting portion 38 of the first strain body 30A is similarly formed in an arc shape when viewed in the Z-axis direction. The force receiving body side connecting portion 38 may overlap the second connecting portion 34 and the third connecting portion 35 when viewed in the Z-axis direction. The force receiving body side pedestal 39 and the thin wall portion 40 may also be formed in an arc shape along at least one of the peripheral edge of the force receiving body 20 and the peripheral edge of the fixed body 25.

As shown in FIG. 15, the force-receiving body-side pedestal 39 of the force-receiving body-side connecting portion 38 of the first strain body 30A may be located closer to the central axis CL than the fixed body-side pedestal 33. More specifically, as shown in FIG. 15, the force-receiving body side pedestal 39 located on the positive side in the X-axis direction is more negative in the X-axis direction than the fixed body side pedestal 33 located on the positive side in the X-axis direction. Located on the side. The force receiving body side pedestal 39 located on the negative side in the X-axis direction is located on the positive side in the X-axis direction rather than the fixed body side pedestal 33 located on the negative side in the X-axis direction.

As shown in FIG. 15, a second recess 43 may be formed in the thin wall portion 40 of the force receiving body side connection portion 38. The second recess 43 may be formed on the surface of the thin portion 40 on the fixed body 25 side. The second recess 43 may be formed in an arc shape when viewed in the Y-axis direction. In this case, the thin portion 40 can be more elastically deformed when force or moment is applied to the force receiving body 20. Therefore, the displacement of the distal end portion 36a of the displacement portion 36 in the Z-axis direction can be further increased.

The fixed body side connecting portions 32 of the second to fourth flexure bodies 30B to 30D are also formed in the same manner as the first flexure bodies 30A. The force-receiving body-side connecting portions 38 of the second strain-generating body 30B to the fourth strain-generating body 30D are also formed similarly to the force-receiving body-side connecting portion 38 of the first strain-generating body 30A.

In this embodiment, as shown in FIG. 16, the insulator of the first displacement electrode substrate Ed1 and the insulator of the second displacement electrode substrate Ed2 are integrated to form a common insulator IBdc. The common insulator IBdc has a circular planar shape. The displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 are formed separately and spaced apart from each other. Each of the displacement electrodes Ed may have a substantially semicircular planar shape. When viewed in the Z-axis direction, the arcuate outer edge of the displacement electrode Ed may be formed concentrically with the outer edge of the common insulator IBdc. However, the planar shape of the common insulator IBdc and the planar shape of the displacement electrode Ed are arbitrary.

The planar shape of the common insulator IBfc (see FIG. 17), which integrates the insulators of the fixed electrode substrates Ef1 and Ef2, is circular, similar to the planar shape of the common insulator IBdc of the displacement electrode substrates Ed1 and Ed2. Good too. The planar shape of the common fixed electrode Efc (see FIG. 17) that integrates the fixed electrodes Ef of the fixed electrode substrates Ef1 and Ef2 may also be circular. However, the planar shape of the common insulator IBfc and the planar shape of the common fixed electrode Efc are arbitrary.

In the force sensor 10 according to the present embodiment, the change in the capacitance value of each capacitive element C1 to C8 when force or moment is applied to the force receiving body 20 is similar to the change shown in FIG. 12. Therefore, detailed explanation will be omitted.

As described above, according to the present embodiment, the displacement portion 36 of the first strain body 30A moves toward the second end of the first connecting portion 31 in a direction intersecting the X-axis direction when viewed in the Z-axis direction. 31b. As a result, even if the second connecting portion 34 and the third connecting portion 35 are formed in an arc shape when viewed in the Z-axis direction, the tip portion 36a of the displacement portion 36 when the force Fy is applied The displacement in the Z-axis direction can be increased. Therefore, the change in capacitance value can be increased, and the detection sensitivity of the force sensor 10 can be improved.

Further, according to the present embodiment, the first end portion 31a of the first connecting portion 31 is connected to the force receiving body 20 via the thin wall portion 40. Thereby, even if the second connecting portion 34 and the third connecting portion 35 are formed in an arc shape when viewed in the Z-axis direction, the thin portion 40 can be elastically deformed. Therefore, the displacement of the distal end portion 36a of the displacement portion 36 in the Z-axis direction can be further increased, and the detection sensitivity of the force sensor 10 can be further improved.

Further, according to the present embodiment, when viewed in the Z-axis direction, the force receiving body 20 and the fixed body 25 are formed in a circular shape, and the second connecting portion 34 and the third connecting portion 35 are connected to the force receiving body. It is formed in an arc shape along at least one of the periphery of the fixing body 20 and the periphery of the fixed body 25 . This makes it possible to improve the space efficiency of each strain body 30A to 30D, and to downsize the force sensor 10. Moreover, the load resistance of the force sensor 10 can be improved, and the reliability of the force sensor 10 can be improved.

Further, according to the present embodiment, the displacement portion 36 of each strain body 30A to 30D extends from the second end portion 31b of the corresponding first connection portion 31 toward the center of the force receiving body 20. . This makes it possible to improve the space efficiency of each strain body 30A to 30D, and to downsize the force sensor 10.

(Modification 3)
In the present embodiment described above, an example has been described in which the displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 are formed separately and spaced apart from each other. However, this embodiment is not limited to this. For example, as shown in FIG. 18, the displacement electrode Ed of the first displacement electrode substrate Ed1 and the displacement electrode Ed of the second displacement electrode substrate Ed2 may be integrated to form a common displacement electrode Edc. In this case, the planar shape of the common displacement electrode Edc may be circular. The fixed electrodes Ef of the fixed electrode substrates Ef1 and Ef2 may be formed separately. In this case, the fixed electrode may have the same planar shape as the displacement electrode Ed shown in FIG. The same applies to the third to eighth displacement electrode substrates Ed3 to Ed8 and the third to eighth fixed electrode substrates Ef3 to Ef8. FIG. 18 is a plan view of the first strain body 30A showing a modification of the detection element 70 of FIG. 15.

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.

Claims (10)

a first sensor body subjected to the action of a force or moment to be detected;
a second sensor body disposed at a different position from the first sensor body in a first direction;
a strain-generating body that connects the first sensor body and the second sensor body and is elastically deformed by the action of a force or moment received by the first sensor body;
a detection element that detects displacement caused by elastic deformation of the strain body;
a detection circuit that outputs an electric signal indicating a force or moment acting on the first sensor body based on a detection result of the detection element;
Equipped with
A direction perpendicular to the first direction is a second direction, a direction perpendicular to the first direction and perpendicular to the second direction is a third direction,
The strain body includes a first connecting portion extending in the first direction from a first end connected to the first sensor body to a second end located on the opposite side of the first end; a second sensor body side connection part that connects the second end of the first connection part to the second sensor body,
The second sensor body side connection part is a pair of pedestals connected to the second sensor body, and includes a pair of pedestals located on both sides of the second end in the second direction, and a pair of pedestals located on both sides of the second end in the second direction. a second connecting portion extending in the second direction from the second end to one of the pedestals when viewed; and a second connecting portion extending from the second end to the other pedestal when viewed in the third direction; a third connecting portion extending in the direction; and a displacement portion extending from the second end in a direction intersecting the second direction when viewed in the first direction,
The detection element detects a change in capacitance value based on displacement of the tip of the displacement part.
Force sensor. The strain body includes a first sensor body side connection part that connects the first end of the first connection part to the first sensor body,
The first sensor body side connection part is a thin part formed along the second direction and the third direction, and includes a thin part connected to the first end of the first connection part.
The force sensor according to claim 1. The detection element includes a fixed electrode substrate provided on the second sensor body, and a displacement electrode substrate provided at the tip of the displacement portion and facing the fixed electrode substrate.
The force sensor according to claim 1. The fixed electrode substrate includes a first fixed electrode substrate located on one side of the pedestal with respect to the central axis of the flexure-generating body, and a first fixed electrode substrate located on the other side of the pedestal with respect to the central axis of the flexure-generating body. a second fixed electrode substrate,
The force sensor according to claim 3. The displacement electrode substrate includes a first displacement electrode substrate located on one side of the pedestal with respect to the central axis of the strain-generating body, and a first displacement electrode substrate located on the other side of the pedestal with respect to the central axis of the strain-generating body. a second displacement electrode substrate;
The force sensor according to claim 3. The displacement portion extends in the third direction from the second end of the first connection portion.
The force sensor according to claim 1. When viewed in the first direction, the second sensor body side connection portion is formed in a straight line along the second direction.
The force sensor according to claim 1. When viewed in the first direction, the first sensor body and the second sensor body are formed in a circular shape,
When viewed in the first direction, the second sensor body side connection portion is formed in an arc shape along at least one of a peripheral edge of the first sensor body and a peripheral edge of the second sensor body.
The force sensor according to claim 1. The first sensor body and the second sensor body are connected by the four strain bodies,
The four flexure bodies include a first flexure body, a second flexure body, a third flexure body, and a fourth flexure body,
The first direction is the Z-axis direction in an XYZ three-dimensional coordinate system,
The first strain body is arranged on the positive side in the Y-axis direction with respect to the center of the first sensor body, and the second strain body is arranged on the negative side in the X-axis direction with respect to the center of the first sensor body. The third strain-generating body is arranged on the negative side in the Y-axis direction with respect to the center of the first sensor body, and the fourth strain-generating body is arranged on the positive side in the X-axis direction with respect to the center of the first sensor body. is located,
The force sensor according to claim 1. The displacement portion extends from the second end of the corresponding first connection portion toward the center of the first sensor body.
The force sensor according to claim 9.

Images