Force sensor

Abstract

To provide a force sensor that enables simplification of a structure.SOLUTION: A force sensor according to the present invention comprises: a force reception body; a support body; a strain generation body that connects the force reception body and support body; a detection element that detects a displacement caused by elastic deformation of the strain generation body; and a detection circuit that outputs an electric signal indicative of force or momentum acting on the force reception body on the basis of a detection result of the detection element. The strain generation body includes: an elastic deformation body that extends in a first direction ranging from a force reception body side end part connected to the force reception body to a support body side end part connected to the support body; and a displacement body that protrudes in a second direction orthogonal to the first direction from the elastic deformation body. The detection element includes: a stationary electrode substrate that is provided in the support body; and a displacement electrode substrate that is provided in the displacement body, and faces the stationary electrode substrate.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a force sensor. [Background technology]

[0002] Force sensors that output a force acting in a predetermined axial direction and a moment (torque) acting around a predetermined rotation axis as an electrical signal have been known. Force sensors are widely used for force control in various robots, including industrial robots, collaborative robots, life support robots, medical robots, and service robots. Therefore, there is a demand for high-performance and high-sensitivity force sensors, but there is also a demand for lower prices for force sensors. However, because force sensors have a complex structure, it has been difficult to achieve low prices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6257017 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in consideration of the above points, and an object of the present invention is to provide a force sensor that can have a simplified structure. [Means for solving the problem]

[0005] The present invention provides a force receiving body that receives the force or moment to be detected; a support body disposed on one side of the force receiving body in the first direction and supporting the force receiving body; a strain generating body that connects the force receiving body and the support body and that elastically deforms due to the action of a force or moment received by the force receiving body; a detection element for detecting a displacement caused by elastic deformation of the strain generating body; a detection circuit that outputs an electrical signal indicating the force or moment acting on the strain-generating body based on the detection result of the detection element, the strain generating body includes an elastic deformation body extending in the first direction from a force receiving body side end connected to the force receiving body to a support body side end connected to the support body, and a displacement body protruding from the elastic deformation body in a second direction perpendicular to the first direction, a force sensor, wherein the detection element includes a fixed electrode substrate provided on the support body and a displacement electrode substrate provided on the displacement body and facing the fixed electrode substrate; to provide.

[0006] In the above-mentioned force sensor, a direction perpendicular to the first direction and the second direction is a third direction; The dimension of the elastically deformable body in the third direction is larger than the dimension of the elastically deformable body in the second direction. This may be done.

[0007] In addition, in the above-mentioned force sensor, the strain generating body includes two displacement bodies protruding in the second direction on both sides of the elastic deformation body, The detection element includes two of the fixed electrode substrates and two of the displacement electrode substrates facing the corresponding fixed electrode substrates; The displacement electrode substrate may be provided on each of the displacement bodies.

[0008] In addition, in the above-mentioned force sensor, the force receiving body and the support body are connected by four of the 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 the XYZ three-dimensional coordinate system, When viewed in the Z-axis direction, the first flexure body is disposed on the negative side of the Y-axis direction with respect to the center of the force receiving body, the second flexure body is disposed on the positive side of the X-axis direction with respect to the center of the force receiving body, the third flexure body is disposed on the positive side of the Y-axis direction with respect to the center of the force receiving body, and the fourth flexure body is disposed on the negative side of the X-axis direction with respect to the center of the force receiving body, the second direction of the first flexure body and the third flexure body is defined as an X-axis direction, The second direction of the second flexure body and the fourth flexure body is defined as a Y-axis direction. This may be done.

[0009] In addition, in the above-mentioned force sensor, The displacement body protrudes in the second direction from the elastic deformation body on one side and does not protrude on the other side. This may be done.

[0010] In addition, in the above-mentioned force sensor, a plurality of the displacement electrode substrates are provided on the displacement body; The support body is provided with the fixed electrode substrates facing each of the displacement electrode substrates. This may be done.

[0011] In addition, in the above-mentioned force sensor, the force receiving body and the support body are connected by four of the 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 the XYZ three-dimensional coordinate system, When viewed in the Z-axis direction, the first flexure body is disposed on the negative side of the Y-axis direction with respect to the center of the force receiving body, the second flexure body is disposed on the positive side of the X-axis direction with respect to the center of the force receiving body, the third flexure body is disposed on the positive side of the Y-axis direction with respect to the center of the force receiving body, and the fourth flexure body is disposed on the negative side of the X-axis direction with respect to the center of the force receiving body, the second direction of the first flexure body and the third flexure body is defined as an X-axis direction, the second direction of the second flexure element and the fourth flexure element is defined as a Y-axis direction, The displacement body of the first strain body and the displacement body of the second strain body face each other, The displacement body of the third flexure body and the displacement body of the fourth flexure body face each other. This may be done.

[0012] In addition, in the above-mentioned force sensor, The force receiving body includes a first force receiving body opening separating the force receiving body side end of the first flexure body from the force receiving body side end of the second flexure body, and a second force receiving body opening separating the force receiving body side end of the third flexure body from the force receiving body side end of the fourth flexure body. This may be done.

[0013] In addition, in the above-mentioned force sensor, The support body includes a first support body opening that separates the support body side end of the second flexure body from the support body side end of the third flexure body, and a second support body opening that separates the support body side end of the fourth flexure body from the support body side end of the first flexure body. This may be done.

[0014] In addition, in the above-mentioned force sensor, the force receiving body includes a force receiving body main body portion and a force receiving body thin-walled portion that is connected to the force receiving body side end portion of the strain generating body and is thinner than the force receiving body main body portion. This may be done.

[0015] In addition, in the above-mentioned force sensor, the support body includes a support body main body portion and a support body thin-wall portion connected to the support body side end portion of the strain generating body and thinner than the support body body portion, This may be done.

[0016] In addition, in the above-mentioned force sensor, the force receiving body and the support body are connected by a plurality of the strain bodies, the detection element is composed of an even number of the displacement electrode substrates, the number of which is smaller than the number of the displacement bodies; some of the displacement bodies are each provided with the displacement electrode substrate, and other of the displacement bodies are not provided with the displacement electrode substrate; When a moment around an axis along the first direction acts on the force sensor, some of the displacement electrode substrates move away from the opposing fixed electrode substrate, and the remaining displacement electrode substrates move closer to the opposing fixed electrode substrate. This may be done.

[0017] In addition, in the above-mentioned force sensor, The strain element includes two displacement elements protruding in the second direction on both sides of the elastic deformation element. This may be done.

[0018] In addition, in the above-mentioned force sensor, The displacement body protrudes in the second direction from the elastic deformation body on one side and does not protrude on the other side. This may be done. [Effects of the Invention]

[0019] According to the present invention, the structure can be simplified. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a perspective view showing an example of a robot to which the force sensor according to the first embodiment is applied. [Figure 2] FIG. 2 is a cross-sectional view showing the force sensor according to the first embodiment. [Figure 3] FIG. 3 is a plan view showing the sensor shown in FIG. [Figure 4] FIG. 4 is a front view showing the strain generating element shown in FIG. [Figure 5] FIG. 5 is a planar development view of the strain element shown in FIG. [Figure 6] FIG. 6 is a front view schematically showing the deformation state of the strain generating body when the force receiving body receives a force in the X-axis direction positive side. [Figure 7]FIG. 7 is a table showing changes in the capacitance value of each capacitance element in the force sensor shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view showing the force sensor according to the second embodiment. [Figure 9] FIG. 9 is a plan view showing the force sensor shown in FIG. [Figure 10] FIG. 10 is a table showing changes in the capacitance value of each capacitance element in the force sensor shown in FIG. [Figure 11] FIG. 11 is a cross-sectional view showing a force sensor according to the third embodiment. [Figure 12] FIG. 12 is a plan view showing the force sensor shown in FIG. [Figure 13] FIG. 13 is a table showing changes in the capacitance value of each capacitance element in the force sensor shown in FIG. [Figure 14] FIG. 14 is a perspective view showing a force sensor according to the fourth embodiment. [Figure 15] FIG. 15 is a cross-sectional view showing a force sensor according to the fifth embodiment. [Figure 16] FIG. 16 is a plan view showing the force sensor shown in FIG. [Figure 17] FIG. 17 is a front view schematically showing the deformation state of the strain generating body when the force receiving body receives a force in the positive Z-axis direction. [Figure 18] FIG. 18 is a front view schematically showing the deformation state of the strain generating body when the force receiving body receives a force on the negative side in the Z axis direction. [Figure 19] FIG. 19 is a table showing changes in the capacitance value of each capacitance element in the force sensor shown in FIG. [Figure 20] FIG. 20 is a table showing the main axis sensitivity and the other axis sensitivity based on the change in the capacitance value shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings attached to this specification, the scale and aspect ratios of the actual objects have been appropriately changed and exaggerated for the sake of convenience in illustration and understanding.

[0022] In addition, terms such as "parallel," "orthogonal," and "equal," as well as dimensions and values ​​of physical properties, which are used in this specification to specify shapes, geometric conditions, physical properties, and their degrees, are not to be construed as being bound by strict meanings, but rather as including the range within which similar functions can be expected.

[0023] (First embodiment) First, a force sensor according to a first embodiment of the present invention will be described with reference to FIGS.

[0024] First, a robot 1 to which a force sensor 10 is attached will be described with reference to Fig. 1. Examples of the robot 1 include various robots such as industrial robots, collaborative robots, life support robots, medical robots, and service robots. The following description will be given taking an industrial robot as an example. Fig. 1 is a perspective view showing an example of a robot 1 to which the force sensor of this embodiment is applied.

[0025] 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.

[0026] A force sensor 10 is attached to the tip of the robot arm 4. More specifically, a tool 3 is attached to the tip of the robot arm 4. The force sensor 10 is attached between the robot arm 4 and the tool 3. The force sensor 10 is electrically connected to the controller 5 via an electric cable (not shown). Examples of the tool 3 include a gripper and a tool changer (neither of which are shown).

[0027] The controller 5 performs force control of the robot 1 based on the electrical signal output from the force sensor 10. In this way, the operations of the robot body 2 and the tool 3 are controlled.

[0028] The force sensor according to the present embodiment will be described below with reference to Figs. 2 to 5. Fig. 2 is a cross-sectional view showing a force sensor 10 according to the first embodiment. Fig. 3 is a plan view showing the force sensor 10 of Fig. 2. Fig. 4 is a front view showing the first flexure element 40A of Fig. 2. Fig. 5 is a planar development view of each of the flexure elements 40A to 40D of the force sensor 10 shown in Fig. 3.

[0029] In the following explanation, an XYZ three-dimensional coordinate system is defined, the Z-axis direction (first direction) is the up-down direction, and the force sensor 10 is arranged so that the force receiving member 20 is arranged on the upper side and the support member 30 is arranged on the lower side. Therefore, the force sensor 10 in this embodiment is not limited to being used in a position in which the Z-axis direction is the up-down direction. In addition, it is arbitrary whether the force receiving member 20 or the support member 30 is arranged on the upper side or the lower side.

[0030] The force sensor 10 has a function of outputting a force acting in a predetermined axial direction and a moment (torque) acting around a predetermined rotation axis as an electrical signal. However, this is not limited thereto, and the force sensor 10 may be configured to output only one of the force and the moment as an electrical signal, or may be configured to output at least one axial component of the force or the moment as an electrical signal.

[0031] 2 and 3, the force sensor 10 includes a force receiving body 20, a support body 30, strain generating bodies 40A to 40D, a detection element 60, a detection circuit 70, and an exterior body 80. Each of the components will be described in more detail below.

[0032] Force receiving body 20 is subjected to the action of the force or moment to be detected. This action causes force receiving body 20 to move relative to support body 30. In the example of FIG. 1 described above, force receiving body 20 is fixed to tool 3 with a bolt or the like, and receives a force or moment from tool 3.

[0033] Force receiving body 20 is formed along the X-axis direction and the Y-axis direction. As shown in FIG. 3, force receiving body 20 may include force receiving body central opening 20a. In this case, the planar shape of force receiving body 20 may be a roughly circular ring shape. Force receiving body central opening 20a is omitted from FIG. 2. Force receiving body 20 may also be formed in a flat plate shape.

[0034] As shown in Fig. 2, support body 30 supports force receiving body 20. Support body 30 is disposed on the negative side of force receiving body 20 in the Z-axis direction. Force receiving body 20 and support body 30 are disposed at different positions in the Z-axis direction, and support body 30 is spaced apart from force receiving body 20. In the example of Fig. 1, support body 30 is fixed to the tip of robot arm 4 with a bolt or the like, and is supported by robot main body 2.

[0035] Support body 30 is formed along the X-axis direction and the Y-axis direction. As shown in FIG. 3, support body 30 may include support body central opening 30a. In this case, the planar shape of support body 30 may be a roughly circular ring shape. In plan view, support body central opening 30a may overlap with force receiving body central opening 20a. Support body central opening 30a is omitted in FIG. 2. Support body 30 may also be formed in a flat plate shape.

[0036] At least one of the planar shapes of force receiving body 20 and support body 30 may be a planar shape other than a circular ring shape. In this case, one of the planar shapes of force receiving body 20 and support body 30 may be circular, and the other may be a shape other than circular. For example, the planar shape of force receiving body 20 may be a circular shape that does not include force receiving body central opening 20a. Alternatively, the planar shape of force receiving body 20 may be rectangular (e.g., rectangular or square). The same applies to the planar shape of support body 30.

[0037] 2 and 3, flexure bodies 40A to 40D connect force receiving body 20 and support body 30. Flexure bodies 40A to 40D are disposed between force receiving body 20 and support body 30, and are connected to force receiving body 20 and support body 30. Force receiving body 20 is supported by support body 30 via flexure bodies 40A to 40D.

[0038] In this embodiment, the force receiving body 20 and the support body 30 are connected by four flexure bodies 40A to 40D. The four flexure bodies 40A to 40D include a first flexure body 40A, a second flexure body 40B, a third flexure body 40C, and a fourth flexure body 40D. As shown in FIG. 3 , when viewed in the Z-axis direction, the first flexure body 40A is disposed on the negative side of the Y-axis direction with respect to the center O of the force receiving body 20. Similarly, when viewed in the Z-axis direction, the second flexure body 40B is disposed on the positive side of the X-axis direction with respect to the center O of the force receiving body 20, and the third flexure body 40C is disposed on the positive side of the Y-axis direction with respect to the center O of the force receiving body 20. The fourth flexure body 40D is disposed on the negative side of the X-axis direction with respect to the center O of the force receiving body 20. In other words, the center O of the force receiving body 20 is located between the first flexure body 40A and the third flexure body 40C, and the center O of the force receiving body 20 is located between the second flexure body 40B and the fourth flexure body 40D. The number of flexure bodies connecting the force receiving body 20 and the support body 30 is not limited to four, but may be two, three, five or more, or any other number. The force receiving body 20 and the support body 30 may be connected by only one flexure body. In this case, if the detection element 60 is configured with two capacitance elements as shown in FIG. 4, it is possible to detect two-axis components of the force. Details will be described later. Alternatively, the detection element 60 may be configured with only one capacitance element to detect a one-axis component of the force.

[0039] The strain generating bodies 40A to 40D will now be described in more detail.

[0040] The flexure bodies 40A to 40D according to this embodiment are configured to elastically deform, generate strain, and displace due to the action of a force or moment received by the force receiving body 20. Here, of the four flexure bodies 40A to 40D described above, the first flexure body 40A, whose second direction is the X-axis direction, will be described as an example.

[0041] As shown in FIGS. 2 and 4, the first strain generating body 40A includes an elastic deformation body 41 and a displacement beam .

[0042] Elastically deformable body 41 extends in the Z-axis direction. Elastically deformable body 41 includes a force receiving body-side end portion 43 connected to force receiving body 20 and a support body-side end portion 44 connected to support body 30. Elastically deformable body 41 extends linearly along the Z-axis direction from force receiving body-side end portion 43 to support body-side end portion 44.

[0043] The elastically deformable body 41 according to this embodiment is elastically deformable by the action of a force in a second direction, and is also elastically deformable by the action of a force in a third direction. The second direction is a direction perpendicular to the first direction. The third direction is a direction perpendicular to both the first direction and the second direction. The second direction of the first strain body 40A is the X-axis direction, and the third direction is the Y-axis direction.

[0044] The dimension of the elastically deformable body 41 in the Y-axis direction according to this embodiment is equal to the dimension of the elastically deformable body 41 in the X-axis direction. In this case, the spring constant of the elastically deformable body 41 with respect to the action of a force in the Y-axis direction is equal to the spring constant with respect to the action of a force in the X-axis direction. The cross-sectional shape of the elastically deformable body 41 along the XY plane may be a generally rectangular shape such as a square, or may be a generally circular shape, and is arbitrary.

[0045] The displacement beam 42 is an example of a displacement body. The displacement beam 42 protrudes from the elastically deformable body 41 in the X-axis direction. The first flexure body 40A according to the present embodiment includes two displacement beams 42 protruding in the X-axis direction on both sides of the elastically deformable body 41. One displacement beam 42 protrudes from the elastically deformable body 41 to the negative side in the X-axis direction, and the other displacement beam 42 protrudes from the elastically deformable body 41 to the positive side in the X-axis direction. The displacement beam 42 may extend from the elastically deformable body 41 in the X-axis direction. The displacement beam 42 may be configured as a cantilever supported by the elastically deformable body 41. The displacement beam 42 may be formed linearly along the X-axis direction. The displacement beam 42 is spaced apart from the force receiving body 20 and the support body 30 in the Z-axis direction. The displacement beam 42 may be disposed closer to the support body 30 than the midpoint between the force receiving body side end 43 and the support body side end 44. The displacement beam 42 faces the support body 30.

[0046] The second flexure body 40B has the Y-axis direction as its second direction and the X-axis direction as its third direction. The third flexure body 40C has the X-axis direction as its second direction and the Y-axis direction as its third direction. The fourth flexure body 40D has the Y-axis direction as its second direction and the X-axis direction as its third direction. The second flexure body 40B, the third flexure body 40C, and the fourth flexure body 40D are configured in the same way as the first flexure body 40A, so detailed descriptions of the individual configurations of the second flexure body 40B, the third flexure body 40C, and the fourth flexure body 40D will be omitted.

[0047] As shown in Fig. 3, the displacement beams 42 of the flexure bodies 40A to 40D according to this embodiment are arranged in an annular shape. As described above, the force receiving body 20 and the support body 30 are formed in a circular ring shape when viewed in the Z-axis direction, and the displacement beams 42 of the four flexure bodies 40A to 40D are arranged to form a rectangular annular shape. When viewed in the Z-axis direction, the displacement beams 42 of each of the flexure bodies 40A to 40D are formed linearly along the respective second directions. Note that the arrangement of the four flexure bodies 40A to 40D is not limited to an annular arrangement, and they may be arranged irregularly at any position.

[0048] The first flexure body 40A configured as described above may be formed by machining or casting a plate made of a metal material such as an aluminum alloy or an iron alloy. When formed by machining, the elastic deformation body 41 and the displacement beam 42 are formed into a plate shape so that the Y-axis direction (third direction) is the thickness direction, and are integrally formed from a continuous plate material. This makes it easy to manufacture the first flexure body 40A. The first flexure body 40A formed as described above may be fixed to the force receiving body 20 and the support body 30 with bolts, adhesive, or the like. The same applies to the second flexure body 40B, the third flexure body 40C, and the fourth flexure body 40D. Alternatively, the force receiving body 20, the support body 30, and the flexure bodies 40A to 40D may be integrally formed from a continuous block material by machining (e.g., cutting) or casting.

[0049] The detection element 60 will now be described.

[0050] The detection element 60 is configured to detect displacement caused by elastic deformation of the above-mentioned first strain generating body 40A. The detection element 60 according to this embodiment includes a capacitance element that detects electrostatic capacitance. As shown in FIG. 4, the capacitance element includes a fixed electrode substrate provided on the support body 30 and a displacement electrode substrate provided on the displacement beam 42. The displacement electrode substrate faces the fixed electrode substrate. In this embodiment, the detection element 60 includes a first capacitance element C1 to an eighth capacitance element C8. The detection element 60 includes a displacement electrode substrate provided on each displacement beam 42 and a corresponding fixed electrode substrate.

[0051] 4, the detection element 60 includes two fixed electrode substrates Ef1 and Ef2 and two displacement electrode substrates Ed1 and Ed2 as electrodes for the first flexure body 40A. The displacement electrode substrates Ed1 and Ed2 are disposed on each displacement beam 42 of the first flexure body 40A. One displacement electrode substrate Ed1, Ed2 is disposed on one displacement beam 42. Each fixed electrode substrate Ef1, Ef2 is disposed on the support body 30 at a position facing the corresponding displacement electrode substrate Ed1, Ed2.

[0052] 4, the two fixed electrode substrates Ef1, Ef2 include a first fixed electrode substrate Ef1 and a second fixed electrode substrate Ef2. The first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 are disposed at different positions in the X-axis direction. In this embodiment, the first fixed electrode substrate Ef1 is disposed on the negative side of the X-axis direction relative to the elastic deformable body 41, and the second fixed electrode substrate Ef2 is disposed on the positive side of the X-axis direction relative to the elastic deformable body 41.

[0053] In the present embodiment, the fixed electrode substrates Ef1, Ef2 are arranged on the surface of the support body 30 that faces the force receiving member 20. The fixed electrode substrates Ef1, Ef2 may be joined to the support body 30 with an adhesive or may be fixed with bolts or the like. The fixed electrode substrates Ef1, Ef2 include fixed electrodes Ef that face the corresponding displacement electrode substrates Ed1, Ed2, and insulators IBf that are interposed between the fixed electrodes Ef and the support body 30.

[0054] As shown in FIG. 4 , the two displacement electrode substrates Ed1 and Ed2 include a first displacement electrode substrate Ed1 and a second displacement electrode substrate Ed2. The first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 are disposed at different positions in the X-axis direction. In the present embodiment, the first displacement electrode substrate Ed1 is disposed on the negative side of the X-axis direction relative to the elastic deformation body 41, and is disposed on a displacement beam 42 that protrudes from the elastic deformation body 41 in the negative side in the X-axis direction. The second displacement electrode substrate Ed2 is disposed on the positive side of the X-axis direction relative to the elastic deformation body 41, and is disposed on a displacement beam 42 that protrudes from the elastic deformation body 41 in the positive side in the X-axis direction. The first displacement electrode substrate Ed1 may be disposed at an end of the displacement beam 42 on the negative side in the X-axis direction. The second displacement electrode substrate Ed2 may be disposed at an end of the displacement beam 42 on the positive side in the X-axis direction.

[0055] In the present embodiment, the displacement electrode substrates Ed1, Ed2 are provided on the surface of the displacement beam 42 that faces the support body 30. The displacement electrode substrates Ed1, Ed2 may be joined to the displacement beam 42 with an adhesive or may be fixed with bolts or the like. The displacement electrode substrates Ed1, Ed2 include a displacement electrode Ed facing the corresponding fixed electrode substrates Ef1, Ef2, and an insulator IBd interposed between the displacement electrode Ed and the displacement beam 42.

[0056] The first fixed electrode substrate Ef1 faces the first displacement electrode substrate Ed1. The first fixed electrode substrate Ef1 and the first displacement electrode substrate Ed1 form a first capacitance element C1. The second fixed electrode substrate Ef2 faces the second displacement electrode substrate Ed2. The second fixed electrode substrate Ef2 and the second displacement electrode substrate Ed2 form a second capacitance element C2. The first capacitance element C1 and the second capacitance element C2 form a detection element 60 for the first strain-generating body 40A.

[0057] The first capacitance element C1 and the second capacitance element C2 are arranged at the same position in the Y-axis direction. That is, the first displacement electrode substrate Ed1 and the second displacement electrode substrate Ed2 are arranged at the same position in the Y-axis direction, and the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 are also arranged at the same position in the Y-axis direction.

[0058] In this embodiment, the planar shapes of the fixed electrode substrates Ef1 and Ef2 are rectangular. The planar shapes of the displacement electrode substrates Ed1 and Ed2 are also rectangular. However, the planar shapes of the fixed electrode substrates Ef1 and Ef2 and the displacement electrode substrates Ed1 and Ed2 are not limited to rectangular, and may be other shapes such as circular, polygonal, or elliptical.

[0059] The first fixed electrode substrate Ef1 may be larger than the first displaceable electrode substrate Ed1 when viewed in the Z-axis direction. For example, the planar shape of the first fixed electrode substrate Ef1 may be larger than the planar shape of the first displaceable electrode substrate Ed1. Furthermore, even when the first displaceable electrode substrate Ed1 is displaced in the X-axis direction, Y-axis direction, or Z-axis direction, the first displaceable electrode substrate Ed1 may overlap the first fixed electrode substrate Ef1 as a whole when viewed in the Z-axis direction. In other words, the sizes of the displacement electrode Ed and the fixed electrode Ef may be set so that the displacement electrode Ed and the fixed electrode Ef overlap even when the first displaceable electrode substrate Ed1 is displaced in the X-axis direction, Y-axis direction, or Z-axis direction. In this way, even when the first displaceable electrode substrate Ed1 is displaced, the opposing area between the displacement electrode Ed and the fixed electrode Ef can be prevented from changing, and the change in the opposing area can be prevented from affecting the change in the capacitance value. Therefore, the capacitance value can be changed according to the change in the distance between the displacement electrode Ed and the fixed electrode Ef. Here, the term "opposing area" refers to the area where the displacement electrode Ed and the fixed electrode Ef overlap when viewed in the Z-axis direction. When the displacement beam 42 tilts, the displacement electrode Ed, which is smaller than the fixed electrode Ef, may tilt, changing the opposing area. However, in this case, the tilt angle of the displacement electrode Ed is small. As a result, the distance between the displacement electrode Ed and the fixed electrode Ef is dominant in changing the capacitance value. For this reason, this specification does not consider changes in the opposing area due to the tilt of the displacement electrode Ed, and instead considers changes in the capacitance value to be caused by changes in the distance between the displacement electrode Ed and the fixed electrode Ef. Note that in Figure 6 and other figures described below, the tilt of the displacement beam 42 is exaggerated for clarity. Furthermore, the planar shape of the first fixed electrode substrate Ef1 is not limited to being larger than the planar shape of the first displacement electrode substrate Ef1; the planar shape of the first displacement electrode substrate Ed1 may be larger than the planar shape of the first fixed electrode substrate Ef1.

[0060] Similarly, when viewed in the Z-axis direction, the planar shape of the second fixed electrode substrate Ef2 may also be larger than the planar shape of the second displaceable electrode substrate Ed2. Note that the planar shape of the second displaceable electrode substrate Ed2 may also be larger than the planar shape of the second fixed electrode substrate Ef2.

[0061] The planar shapes of the fixed electrodes Ef of the fixed electrode substrates Ef1 and Ef2 and the insulator IBf may be the same size. However, this is not limited thereto, and the planar shapes of the fixed electrodes Ef and the insulator IBf may be different sizes. The same applies to the planar shapes of the displacement electrodes Ed of the displacement electrode substrates Ed1 and Ed2 and the insulator IBd.

[0062] The first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 may be formed separately and separated from each other, as shown in Fig. 4. However, this is not limiting, and the first fixed electrode substrate Ef1 and the second fixed electrode substrate Ef2 may be integrated into one common fixed electrode substrate. In this case, the insulator IBf and the fixed electrodes Ef may be integrated. Alternatively, even if the fixed electrodes Ef are configured to be separated from each other, the insulator IBf may be integrated.

[0063] The configuration of the first flexure body 40A and the corresponding detection element 60 can be similarly applied to the second flexure body 40B, the third flexure body 40C, and the fourth flexure body 40D.

[0064] 5, the detection element 60 further includes, as electrodes for the second flexure body 40B, two fixed electrode substrates Ef3 and Ef4 provided on the support body 30 and two displacement electrode substrates Ed3 and Ed4 provided on the displacement beam 42. The two fixed electrode substrates Ef3 and Ef4 include a third fixed electrode substrate Ef3 and a fourth fixed electrode substrate Ef4. The two displacement electrode substrates Ed3 and Ed4 include a third displacement electrode substrate Ed3 and a fourth displacement electrode substrate Ed4. The third fixed electrode substrate Ef3 faces the third displacement electrode substrate Ed3, and the fourth fixed electrode substrate Ef4 faces the fourth displacement electrode substrate Ed4. The third fixed electrode substrate Ef3 and the third displacement electrode substrate Ed3 form a third capacitance element C3, and the fourth fixed electrode substrate Ef4 and the fourth displacement electrode substrate Ed4 form a fourth capacitance element C4.

[0065] The third displacement electrode substrate Ed3 and the third fixed electrode substrate Ef3 are arranged on the negative side of the Y axis direction relative to the elastic deformation body 41. The third displacement electrode substrate Ed3 is arranged on a displacement beam 42 that protrudes from the elastic deformation body 41 on the negative side of the Y axis direction. The fourth displacement electrode substrate Ed4 and the fourth fixed electrode substrate Ef4 are arranged on the positive side of the Y axis direction relative to the elastic deformation body 41. The fourth displacement electrode substrate Ed4 is arranged on a displacement beam 42 that protrudes from the elastic deformation body 41 on the positive side of the Y axis direction. The third capacitance element C3 and the fourth capacitance element C4 are arranged at the same position in the X axis direction. The fixed electrode substrates Ef3 and Ef4 have the same configuration as the fixed electrode substrates Ef1 and Ef2 described above. The displacement electrode substrates Ed3 and Ed4 have the same configuration as the displacement electrode substrates Ed1 and Ed2 described above.

[0066] The detection element 60 further includes, as electrodes for the third flexure body 40C, two fixed electrode substrates Ef5 and Ef6 provided on the support body 30 and two displacement electrode substrates Ed5 and Ed6 provided on the displacement beam 42. The two fixed electrode substrates Ef5 and Ef6 include a fifth fixed electrode substrate Ef5 and a sixth fixed electrode substrate Ef6. The two displacement electrode substrates Ed5 and Ed6 include a fifth displacement electrode substrate Ed5 and a sixth displacement electrode substrate Ed6. The fifth fixed electrode substrate Ef5 faces the fifth displacement electrode substrate Ed5, and the sixth fixed electrode substrate Ef6 faces the sixth displacement electrode substrate Ed6. The fifth fixed electrode substrate Ef5 and the fifth displacement electrode substrate Ed5 form a fifth capacitance element C5, and the sixth fixed electrode substrate Ef6 and the sixth displacement electrode substrate Ed6 form a sixth capacitance element C6.

[0067] The fifth displacement electrode substrate Ed5 and the fifth fixed electrode substrate Ef5 are arranged on the positive side of the X-axis direction relative to the elastic deformation body 41. The fifth displacement electrode substrate Ed5 is arranged on a displacement beam 42 that protrudes from the elastic deformation body 41 on the positive side of the X-axis direction. The sixth displacement electrode substrate Ed6 and the sixth fixed electrode substrate Ef6 are arranged on the negative side of the X-axis direction relative to the elastic deformation body 41. The sixth displacement electrode substrate Ed6 is arranged on a displacement beam 42 that protrudes from the elastic deformation body 41 on the negative side of the X-axis direction. The fifth capacitance element C5 and the sixth capacitance element C6 are arranged at the same position in the Y-axis direction. The fixed electrode substrates Ef5 and Ef6 have the same configuration as the fixed electrode substrates Ef1 and Ef2 described above. The displacement electrode substrates Ed5 and Ed6 have the same configuration as the displacement electrode substrates Ed1 and Ed2 described above.

[0068] The detection element 60 further includes, as electrodes for the fourth flexure body 40D, two fixed electrode substrates Ef7 and Ef8 provided on the support body 30 and two displacement electrode substrates Ed7 and Ed8 provided on the displacement beam 42. The two fixed electrode substrates Ef7 and Ef8 include a seventh fixed electrode substrate Ef7 and an eighth fixed electrode substrate Ef8. The two displacement electrode substrates Ed7 and Ed8 include a seventh displacement electrode substrate Ed7 and an eighth displacement electrode substrate Ed8. The seventh fixed electrode substrate Ef7 faces the seventh displacement electrode substrate Ed7, and the eighth fixed electrode substrate Ef8 faces the eighth displacement electrode substrate Ed8. The seventh fixed electrode substrate Ef7 and the seventh displacement electrode substrate Ed7 form a seventh capacitance element C7, and the eighth fixed electrode substrate Ef8 and the eighth displacement electrode substrate Ed8 form an eighth capacitance element C8.

[0069] The seventh displacement electrode substrate Ed7 and the seventh fixed electrode substrate Ef7 are arranged on the positive side of the Y axis direction relative to the elastic deformation body 41. The seventh displacement electrode substrate Ed7 is arranged on a displacement beam 42 that protrudes from the elastic deformation body 41 in the positive side of the Y axis direction. The eighth displacement electrode substrate Ed8 and the eighth fixed electrode substrate Ef8 are arranged on the negative side of the Y axis direction relative to the elastic deformation body 41. The eighth displacement electrode substrate Ed8 is arranged on a displacement beam 42 that protrudes from the elastic deformation body 41 in the negative side of the Y axis direction. The seventh capacitance element C7 and the eighth capacitance element C8 are arranged at the same position in the X axis direction. The fixed electrode substrates Ef7 and Ef8 have the same configuration as the fixed electrode substrates Ef1 and Ef2 described above. The displacement electrode substrates Ed7 and Ed8 have the same configuration as the displacement electrode substrates Ed1 and Ed2 described above.

[0070] Each of the fixed electrode substrates Ef1 to Ef8 described above may be made of a ceramic substrate, a glass epoxy substrate, or an FPC substrate (flexible printed circuit board) on which electrode materials are laminated. The FPC substrate is a printed board formed in the form of a thin film and has flexibility, and may be entirely joined to the support body 30. Each of the fixed electrode substrates Ef1 to Ef8 may be adhered to the support body 30 with an adhesive. The same applies to each of the displacement electrode substrates Ed1 to Ed8. Each of the displacement electrode substrates Ed1 to Ed8 may be adhered to the displacement beam 42 with an adhesive.

[0071] 2, the detection circuit 70 outputs an electric signal indicating the force or moment acting on the strain bodies 40A-40D based on the detection result of the detection element 60. The detection circuit 70 may have a calculation function implemented by, for example, a microprocessor. The detection circuit 70 may also have an A / D conversion function for converting the analog signal received from the detection element 60 into a digital signal, a signal amplification function, and various correction functions. The detection circuit 70 may include a terminal for outputting the electric signal, and the electric signal is transmitted from this terminal to the controller 5 via an electric cable.

[0072] 2 and 3, the exterior body 80 is configured to cover the four flexure bodies 40A to 40D from the outside when viewed in the Z-axis direction. The exterior body 80 may be a cylindrical housing that constitutes the force sensor 10. The flexure bodies 40A to 40D are housed in the exterior body 80. In this embodiment, the cross-sectional shape of the exterior body 80 in plan view (the shape in a cross section along the XY plane) is a circular frame shape.

[0073] As shown in FIG. 2 , exterior body 80 includes force receiver side cover 81 attached to force receiver 20, support body side cover 82 attached to support body 30, and cushioning member 83 interposed between force receiver side cover 81 and support body side cover 82. Force receiver side cover 81 may be attached to force receiver 20 in a sealed manner or may be formed integrally therewith. Support body side cover 82 may be attached to support body 30 in a sealed manner or may be formed integrally therewith. Cushioning member 83 may be formed, for example, with a rubber packing for dust and water resistance. This cushioning member 83 prevents foreign matter such as dust from entering the interior through the gap between force receiver side cover 81 and support body side cover 82. Furthermore, force receiver 20 is displaceable relative to support body 30.

[0074] Next, a method for detecting a force or moment in the force sensor according to this embodiment having the above configuration will be described.

[0075] When a force or moment acts on the force receiving body 20, the force or moment is transmitted to the first flexure body 40A through the fourth flexure body 40D. More specifically, the force or moment is transmitted to the elastic deformation body 41, causing elastic deformation in the elastic deformation body 41. This tilts and displaces the displacement beam 42. As a result, the distance between each of the fixed electrode substrates Ef1 through Ef8 of the detection element 60 and the corresponding displacement electrode substrates Ed1 through Ed8 changes, causing a change in the capacitance value of each of the capacitance elements C1 through C8. This change in capacitance value is detected by the detection element 60 as a displacement occurring in the flexure bodies 40A through 40D. In this case, the change in capacitance value of each of the capacitance elements C1 through C8 may differ. Therefore, the detection circuit 70 can detect the direction and magnitude of the force or moment acting on the force receiving body 20 based on the change in capacitance value of each of the capacitance elements C1 through C8 detected by the detection element 60.

[0076] Here, as an example, changes in the capacitance values ​​of the first capacitance element C1 and the second capacitance element C2 when a force Fx in the X-axis direction acts on the first strain body 40A alone will be described with reference to Fig. 6. Fig. 6 is a front view schematically showing the deformation state of the first strain body 40A when the force receiving body 20 receives a force Fx on the positive side in the X-axis direction.

[0077] When a force Fx acts on the first flexure body 40A in the positive X-axis direction, the elastic deformation body 41 of the first flexure body 40A elastically deforms, as shown in FIG. 6. In this case, the force receiving body side end 43 of the elastic deformation body 41 is displaced in the positive X-axis direction, and the elastic deformation body 41 elastically deforms so as to bend in the positive X-axis direction. For simplicity of illustration, FIG. 6 shows a state in which the elastic deformation body 41 is tilting. The displacement beam 42 tilts and displaces. As a result, the first displacement electrode substrate Ed1 rises and moves away from the first fixed electrode substrate Ef1. The inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 increases, and the capacitance value of the first capacitance element C1 decreases. Meanwhile, the second displacement electrode substrate Ed2 descends and moves closer to the second fixed electrode substrate Ef2. The inter-electrode distance between the second displaceable electrode substrate Ed2 and the second fixed electrode substrate Ef2 decreases, and the electrostatic capacitance value of the second capacitance element C2 increases.

[0078] The force Fx acting on the first strain element 40A alone can be calculated using the following formula. In the following formula, for convenience, the force or moment and the change in capacitance value are connected with "=". However, since the force or moment and the capacitance value are different physical quantities, the force Fx is actually calculated by converting the change in capacitance value. In the following formula, C1 and C2 represent the change in capacitance value of each capacitance element C1 and C2. [Formula 1] Fx=-C1+C2

[0079] When a moment My about the Y-axis acts on the first strain body 40A alone, the elastic deformation body 41 elastically deforms as in Fig. 6. The capacitance value of the first capacitance element C1 decreases, and the capacitance value of the second capacitance element C2 increases. Therefore, the moment My is calculated in the same manner as in Equation 1 above. [Formula 2] My=-C1+C2

[0080] When a force Fy in the Y-axis direction acts on the first flexure body 40A alone, it can be assumed that there is no change in the capacitance value of each of the capacitance elements C1 and C2. This is because, as described above, the first capacitance element C1 and the second capacitance element C2 are disposed at the same position in the Y-axis direction. In this case, the change in capacitance value at the positive side portion of each of the capacitance elements C1 and C2 in the Y-axis direction cancels out the change in capacitance value at the negative side portion. Similarly, when a moment Mx about the X-axis acts on the first flexure body 40A alone, it can be assumed that there is no change in the capacitance value of each of the capacitance elements C1 and C2.

[0081] When a force Fz in the Z-axis direction acts on the first strain body 40A alone, it can be assumed that there is no change in the capacitance value of each of the capacitance elements C1 and C2. As described above, the elastically deformable body 41 extends in the Z-axis direction from the force receiving body side end 43 to the support body side end 44, so that the elastically deformable body 41 has increased rigidity against forces in the Z-axis direction and acts essentially as a rigid body. The elastically deformable body 41 does not elastically deform in the Z-axis direction, and it can be assumed that there is no expansion or contraction of the elastically deformable body 41 in the Z-axis direction.

[0082] In this way, the force sensor 10 in which the force receiving body 20 and the support body 30 are connected only by the first strain body 40A can detect the force Fx and the moment My. This force sensor 10 may be used in an environment in which only one of the force Fx and the moment My acts.

[0083] Next, changes in the capacitance value of each of the capacitance elements C1 to C8 when a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a moment Mz about the Z-axis act on force receiving body 20 of force sensor 10 shown in Fig. 5 will be described using Fig. 7. Fig. 7 is a table showing changes in the capacitance value of each of the capacitance elements C1 to C8.

[0084] (When +Fx is applied) First, a case where force Fx acts on force receiving body 20 in the positive direction of the X axis will be described.

[0085] In this case, the first strain generating body 40A is elastically deformed as shown in Fig. 6, the capacitance value of the first capacitance element C1 decreases, and the capacitance value of the second capacitance element C2 increases. This is indicated by a "- (minus)" for C1 and a "+ (plus)" for C2 in the row of Fx in the table shown in Fig. 7.

[0086] The second flexure body 40B rotates around the Y-axis (clockwise toward the positive side in the Y-axis direction). However, the third capacitance element C3 and the fourth capacitance element C4 are disposed at the same position in the X-axis direction. Therefore, similar to when a force Fy in the Y-axis direction acts on the first flexure body 40A, no change in capacitance value occurs for the third capacitance element C3 as a whole and the fourth capacitance element C4 as a whole. This is indicated by "0 (zero)" for C3 and C4 in the row for Fx in the table shown in FIG. 7.

[0087] The third flexure body 40C elastically deforms in the same manner as the first flexure body 40A shown in Fig. 6. As a result, the capacitance value of the fifth capacitance element C5 increases and the capacitance value of the sixth capacitance element C6 decreases. This is indicated by a "+" for C5 and a "-" for C6 in the row of Fx in the table shown in Fig. 7.

[0088] The fourth flexure body 40D rotates around the Y-axis like the second flexure body 40B. However, as described above, the seventh capacitance element C7 and the eighth capacitance element C8 are arranged at the same position in the X-axis direction. Therefore, no change in capacitance value occurs for the seventh capacitance element C7 as a whole and the eighth capacitance element C8 as a whole. This is indicated by "0 (zero)" for C7 and C8 in the row of Fx in the table shown in FIG.

[0089] (When +Fy is applied) Next, a case will be described where force Fy acts on force receiving member 20 in the Y-axis direction positive direction. In the following description as well, the symbols in the table of FIG. 7 are determined according to the change in capacitance value, as described above.

[0090] In this case, the first strain generating body 40A rotates around the X-axis (counterclockwise toward the positive side in the X-axis direction). However, as described above, the first capacitance element C1 and the second capacitance element C2 are disposed at the same position in the Y-axis direction. Therefore, no change in the capacitance value occurs for the first capacitance element C1 as a whole and the second capacitance element C2 as a whole.

[0091] The second flexure body 40B elastically deforms in the same manner as the first flexure body 40A shown in FIG. 6, and the capacitance value of the third capacitance element C3 decreases while the capacitance value of the fourth capacitance element C4 increases.

[0092] The third flexure body 40C rotates around the X-axis like the first flexure body 40A. However, the fifth capacitance element C5 and the sixth capacitance element C6 are arranged at the same position in the Y-axis direction. Therefore, there is no change in the capacitance value of the fifth capacitance element C5 as a whole and the sixth capacitance element C6 as a whole.

[0093] The fourth flexure body 40D elastically deforms in the same manner as the first flexure body 40A shown in FIG. 6, and the capacitance value of the seventh capacitance element C7 increases while the capacitance value of the eighth capacitance element C8 decreases.

[0094] (When +Fz is applied) Next, we will explain what happens when force Fz acts on force receiving body 20 in the positive direction of the Z axis. As described above, elastic deformation bodies 41 of each of strain generating bodies 40A to 40D extend in the Z axis direction from support body side end 44 to force receiving body side end 43. This increases the rigidity of elastic deformation bodies 41 against forces in the Z axis direction, and they essentially act as rigid bodies. It can be assumed that elastic deformation bodies 41 do not expand or contract in the Z axis direction, and each elastic deformation body 41 does not elastically deform. Therefore, the capacitance value of each of capacitance elements C1 to C8 does not change. This is indicated by a "0 (zero)" in the row for Fz in the table shown in FIG. 7.

[0095] (When +Mx is applied) Next, a case where a moment Mx (see FIG. 5) about the X-axis (clockwise toward the positive side of the X-axis direction) acts on the force receiving body 20 will be described. In this case, a force Fz acts on the elastic deformation body 41 of the first flexure body 40A in the negative Z-axis direction, and a force Fz acts on the elastic deformation body 41 of the third flexure body 40C in the positive Z-axis direction. As described above, the elastic deformation body 41 extends in the Z-axis direction from the support-side end 44 to the force receiving body-side end 43. This increases the rigidity of the elastic deformation body 41 against forces in the Z-axis direction, and the elastic deformation body 41 essentially acts as a rigid body. The elastic deformation body 41 does not expand or contract in the Z-axis direction, and the force receiving body 20 does not displace. Because the force receiving body 20 does not displace, the elastic deformation body 41 of the second flexure body 40B does not elastically deform, and the elastic deformation body 41 of the fourth flexure body 40D does not elastically deform either. Therefore, the capacitance values ​​of the capacitance elements C1 to C8 do not change. This is shown as "0 (zero)" in the Mx row in the table shown in FIG.

[0096] (When +My is applied) Next, a case where a moment My (see FIG. 5) about the Y-axis (clockwise toward the Y-axis positive side) acts on the force receiving body 20 will be described. In this case, a force Fz acts on the elastic deformation body 41 of the second flexure body 40B in the negative Z-axis direction, and a force Fz acts on the elastic deformation body 41 of the fourth flexure body 40D in the positive Z-axis direction. As described above, the elastic deformation body 41 extends in the Z-axis direction from the support-side end 44 to the force receiving body-side end 43. This increases the rigidity of the elastic deformation body 41 against forces in the Z-axis direction, and the elastic deformation body 41 essentially acts as a rigid body. The elastic deformation body 41 does not expand or contract in the Z-axis direction, and the force receiving body 20 does not displace. The elastic deformation body 41 of the first flexure body 40A does not elastically deform, and the elastic deformation body 41 of the third flexure body 40C does not elastically deform either. Therefore, the capacitance values ​​of the capacitance elements C1 to C8 do not change. This is shown as "0 (zero)" in the My row in the table shown in FIG.

[0097] (When +Mz is applied) Next, a description will be given of a case where moment Mz (see FIG. 5) about the Z axis (clockwise toward the positive side in the Z axis direction) acts on force receiving body 20. In the following description, the symbols in the table of FIG. 7 will be determined as described above according to the change in capacitance value.

[0098] In this case, the first flexure body 40A elastically deforms in the same manner as when a force Fx in the positive X-axis direction is applied, causing the first flexure body 40A to elastically deform in the same manner as the first flexure body 40A shown in Fig. 6, decreasing the capacitance value of the first capacitance element C1 and increasing the capacitance value of the second capacitance element C2.

[0099] The second flexure body 40B elastically deforms in the same manner as when the force Fy in the positive Y-axis direction is applied, causing the second flexure body 40B to elastically deform in the same manner as the first flexure body 40A shown in Fig. 6, decreasing the capacitance value of the third capacitance element C3 and increasing the capacitance value of the fourth capacitance element C4.

[0100] The third strain body 40C is elastically deformed in the same manner as when the negative X-axis direction force Fx is applied, thereby decreasing the capacitance value of the fifth capacitance element C5 and increasing the capacitance value of the sixth capacitance element C6.

[0101] The fourth strain element 40D is elastically deformed in the same manner as when the negative Y-axis force Fy is applied, thereby decreasing the capacitance value of the seventh capacitance element C7 and increasing the capacitance value of the eighth capacitance element C8.

[0102] In this way, force sensor 10 according to the present embodiment can detect force Fx, force Fy, and moment Mz. When force Fx, force Fy, or moment Mz acts on force receiving member 20, a change in the capacitance value of each of capacitance elements C1 to C8 is detected, and the direction and magnitude of the force or moment acting on force receiving member 20 are detected. Then, as shown in FIG. 7, the capacitance value of each of capacitance elements C1 to C8 changes.

[0103] From the table shown in FIG. 7, forces Fx, Fy and moment Mz acting on force receiving member 20 can be calculated using the following equations. This makes it possible to detect the three-axis components of the force. In the following equations, for convenience, the force or moment and the amount of change in capacitance value are connected with "=". However, because force or moment and capacitance value are different physical quantities, in reality, the force or moment is calculated by converting the amount of change in capacitance value. In the following equations, C1 to C8 represent the amount of change in capacitance value in each of capacitance elements C1 to C8. [Formula 3] Fx=-C1+C2 +C5-C6 [Formula 4] Fy= -C3+C4 +C7-C8 [Formula 5] Mz=-C1+C2-C3+C4-C5+C6-C7+C8

[0104] As described above, the force sensor 10 shown in FIG. 5 can detect forces Fx, Fy, and moment Mz as shown in the above-mentioned [Equation 3] to [Equation 5], and is therefore capable of detecting three-axis components of force.

[0105] As described above, according to this embodiment, strain generators 40A-40D connecting force receiving body 20 and support body 30 extend in the Z-axis direction from force receiving body-side end 43 connected to force receiving body 20 to support body-side end 44 connected to support body 30. This allows for simplification of the structure of strain generators 40A-40D. In this case, the price of force sensor 10 can be reduced.

[0106] Furthermore, according to the present embodiment, strain generating bodies 40A-40D connecting force receiving body 20 and support body 30 extend in the Z-axis direction from force receiving body-side end 43 connected to force receiving body 20 to support body-side end 44 connected to support body 30. This makes it possible to suppress elastic deformation of elastic deformable body 41 in the Z-axis direction. Therefore, even when force Fz in the Z-axis direction, moment Mx about the X-axis, or moment My about the Y-axis acts on force receiving body 20, elastic deformation of elastic deformable body 41 can be suppressed. This makes it possible to increase rigidity against force Fz, moment Mx, and moment My, and improve the reliability of force sensor 10.

[0107] Furthermore, according to this embodiment, the displacement beams 42 of the strain generating bodies 40A to 40D protrude from the elastically deformable body 41 in a second direction perpendicular to the Z-axis direction. Fixed electrode substrates Ef1 to Ef8 are provided on the support body 30, and the displacement beams 42 are provided with displacement electrode substrates Ed1 to Ed8 and face the fixed electrode substrates Ef1 to Ef8. As a result, when the elastically deformable body 41 elastically deforms in a direction perpendicular to the Z-axis direction, the displacement beams 42 tilt and are displaced. This makes it possible to change the inter-electrode distance between each of the displacement electrode substrates Ed1 to Ed8 and the corresponding fixed electrode substrates Ef1 to Ef8, thereby changing the capacitance value of each of the capacitance elements C1 to C8. As a result, it is possible to detect force or moment.

[0108] Furthermore, according to this embodiment, the displacement beams 42 protrude from the elastically deformable body 41 in the second direction on both sides of the elastically deformable body 41. Displacement electrode substrates Ed1 to Ed8 are arranged on each of the displacement beams 42, and fixed electrode substrates Ef1 to Ef8 are arranged on the support body 30 so as to face the corresponding displacement electrode substrates Ed1 to Ed8. As a result, when the elastically deformable body 41 elastically deforms in the second direction, some of the displacement electrode substrates Ed1 to Ed8 can be moved away from the corresponding fixed electrode substrates Ef1 to Ef8, and other displacement electrode substrates Ed1 to Ed8 can be moved closer to the corresponding fixed electrode substrates Ef1 to Ef8. This makes it possible to improve detection sensitivity.

[0109] Furthermore, according to this embodiment, the displacement beams 42 of the flexure bodies 40A to 40D extend in a second direction perpendicular to the Z-axis direction. That is, the displacement beams 42 of the first flexure body 40A and the third flexure body 40C extend in the X-axis direction, and the displacement beams 42 of the second flexure body 40B and the fourth flexure body 40D extend in the Y-axis direction. This allows the displacement beams 42 to be displaced when subjected to the action of a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a moment Mz about the Z-axis. This allows the displacement of the displacement electrode substrates Ed1 to Ed8 to be increased, thereby improving the detection sensitivity of forces or moments.

[0110] (Second embodiment) Next, a force sensor according to a second embodiment of the present invention will be described with reference to FIGS.

[0111] The second embodiment shown in Figures 8 to 10 differs mainly in that the dimension of the elastically deformable body in the third direction is larger than the dimension of the elastically deformable body in the second direction, and other configurations are substantially the same as those of the first embodiment shown in Figures 1 to 7. In Figures 8 to 10, the same parts as those in the first embodiment shown in Figures 1 to 7 are designated by the same reference numerals and detailed description thereof will be omitted.

[0112] 8 and 9, the dimension in the third direction of the elastically deformable body 41 according to this embodiment is greater than the dimension in the second direction of the elastically deformable body 41. Fig. 8 is a cross-sectional view showing a force sensor 10 according to the second embodiment. Fig. 9 is a plan view showing the force sensor 10 shown in Fig. 8.

[0113] The dimension in the Y-axis direction of the elastic deformation body 41 of the first flexure body 40A is larger than the dimension in the X-axis direction of the elastic deformation body 41. The second direction of the first flexure body 40A corresponds to the X-axis direction, and the third direction corresponds to the Y-axis direction. In this embodiment, the spring constant of the elastic deformation body 41 of the first flexure body 40A with respect to the action of a force in the Y-axis direction is larger than the spring constant with respect to the action of a force in the X-axis direction.

[0114] Similarly, the dimension in the X-axis direction of the elastic deformation body 41 of the second flexure body 40B is larger than the dimension in the Y-axis direction of the elastic deformation body 41. The second direction of the second flexure body 40B corresponds to the Y-axis direction, and the third direction corresponds to the X-axis direction. In this embodiment, the spring constant of the elastic deformation body 41 of the second flexure body 40B with respect to the action of a force in the X-axis direction is larger than the spring constant with respect to the action of a force in the Y-axis direction.

[0115] Similarly, the dimension in the Y-axis direction of the elastic deformation body 41 of the third flexure body 40C is larger than the dimension in the X-axis direction of the elastic deformation body 41. The second direction of the third flexure body 40C corresponds to the X-axis direction, and the third direction corresponds to the Y-axis direction. In the present embodiment, the spring constant of the elastic deformation body 41 of the third flexure body 40C with respect to the action of a force in the Y-axis direction is larger than the spring constant with respect to the action of a force in the X-axis direction.

[0116] Similarly, the dimension in the X-axis direction of the elastic deformation body 41 of the fourth flexure body 40D is larger than the dimension in the Y-axis direction of the elastic deformation body 41. The second direction of the fourth flexure body 40D corresponds to the Y-axis direction, and the third direction corresponds to the X-axis direction. In the present embodiment, the spring constant of the elastic deformation body 41 of the fourth flexure body 40D with respect to the action of a force in the X-axis direction is larger than the spring constant with respect to the action of a force in the Y-axis direction.

[0117] The cross-sectional shape of the elastically deformable body 41 of each of the flexure bodies 30A to 40D may be a rectangle with the third direction as the longitudinal direction, or an ellipse with the major axis along the third direction. The cross-sectional shape of the elastically deformable body 41 is arbitrary as long as the dimension in the third direction is greater than the dimension in the second direction.

[0118] In this embodiment, a case where a force Fx acting on force receiving member 20 in the positive X-axis direction will be described.

[0119] As described above, the dimension in the X-axis direction of the elastic deformation body 41 of the second flexure body 40B is larger than the dimension in the Y-axis direction, and the dimension in the X-axis direction of the elastic deformation body 41 of the fourth flexure body 40D is larger than the dimension in the Y-axis direction. This increases the rigidity of the second flexure body 40B and the fourth flexure body 40D against the force Fx, and they essentially act as rigid bodies. Therefore, the elastic deformation body 41 of the second flexure body 40B and the elastic deformation body 41 of the fourth flexure body 40D do not elastically deform, and the force receiving body 20 does not displace. Because the force receiving body 20 does not displace, the elastic deformation body 41 of the first flexure body 40A and the elastic deformation body 41 of the third flexure body 40C do not elastically deform either. Therefore, the capacitance values ​​of the capacitance elements C1 to C8 do not change.

[0120] In this embodiment, a case where a force Fy acting on force receiving member 20 in the positive Y-axis direction will be described.

[0121] As described above, the dimension in the Y-axis direction of the elastic deformation body 41 of the first flexure body 40A is larger than the dimension in the X-axis direction, and the dimension in the Y-axis direction of the elastic deformation body 41 of the third flexure body 40C is larger than the dimension in the X-axis direction. This increases the rigidity of the first flexure body 40A and the third flexure body 40C against the force Fy, and they essentially act as rigid bodies. Therefore, the elastic deformation body 41 of the first flexure body 40A and the elastic deformation body 41 of the third flexure body 40C do not elastically deform, and the force receiving body 20 does not displace. Because the force receiving body 20 does not displace, the elastic deformation body 41 of the second flexure body 40B and the elastic deformation body 41 of the fourth flexure body 40D do not elastically deform either. Therefore, the capacitance values ​​of the capacitance elements C1 to C8 do not change.

[0122] In this embodiment, the change in capacitance value of each of capacitance elements C1 to C8 when moment Mz about the Z axis acts on force receiving member 20 will be described using Fig. 10. Fig. 10 is a table showing the change in capacitance value of each of capacitance elements C1 to C8. In the following description, the symbols in the table of Fig. 10 are determined in the same way as in Fig. 7 according to the change in capacitance value.

[0123] The dimension in the X-axis direction of the elastic deformation body 41 of the first flexure body 40A is smaller than the dimension in the Y-axis direction, and the dimension in the X-axis direction of the elastic deformation body 41 of the third flexure body 40C is smaller than the dimension in the Y-axis direction, so that the elastic deformation body 41 of the first flexure body 40A and the elastic deformation body 41 of the third flexure body 40C can elastically deform in the X-axis direction.

[0124] The dimension in the Y-axis direction of the elastic deformation body 41 of the second flexure body 40B is smaller than the dimension in the X-axis direction, and the dimension in the Y-axis direction of the elastic deformation body 41 of the fourth flexure body 40D is smaller than the dimension in the X-axis direction, so that the elastic deformation body 41 of the second flexure body 40B and the elastic deformation body 41 of the fourth flexure body 40D can elastically deform in the Y-axis direction.

[0125] Therefore, similarly to the force sensor 10 shown in FIG. 5, the displacement beams 42 of the strain-generating bodies 40A to 40D are displaced, and the electrostatic capacitance values ​​of the capacitance elements C1 to C8 change.

[0126] In this way, force sensor 10 according to the present embodiment can detect moment Mz. When moment Mz acts on force receiving member 20, a change in the capacitance value of each of capacitance elements C1 to C8 is detected, and the direction and magnitude of moment Mz acting on force receiving member 20 are detected. Then, as shown in FIG. 10, the capacitance value of each of capacitance elements C1 to C8 changes.

[0127] From the table shown in Figure 10, moment Mz acting on force receiving member 20 can be calculated using the following equation. [Equation 6] below is the same as [Equation 5] above. This makes it possible to calculate one axial component of the force, i.e., moment Mz about the Z axis. [Formula 6] Mz=-C1+C2-C3+C4-C5+C6-C7+C8

[0128] In the above-mentioned [Equation 6], the moment Mz is calculated using the capacitance value based on the displacement electrode substrates Ed1 to Ed8 provided on each displacement beam 42. However, the method for calculating the moment Mz according to this embodiment is not limited to this.

[0129] For example, the detection element 60 may be configured with an even number of displacement electrode substrates that is smaller than the number of displacement beams 42. That is, the moment Mz may be detected based on the displacement electrode substrates provided on only some of the displacement beams 42. In this case, some of the displacement beams 42 may be provided with a displacement electrode substrate, while other displacement beams 42 may not be provided with a displacement electrode substrate. The fixed electrode substrates may be provided on the support 30 at positions facing the corresponding displacement electrode substrates. When a moment around the Z axis acts on the force sensor 10, some of the displacement electrode substrates may move away from the opposing fixed electrode substrate, and the remaining displacement electrode substrates may move closer to the opposing fixed electrode substrate.

[0130] More specifically, the formula for calculating the moment Mz may be any of the following formulas instead of the above-mentioned [Formula 6]. In this case, as shown in [Formula 6], the moment Mz can be calculated without using all of the capacitance elements C1 to C8. [Formula 7] Mz=-C1+C2-C5+C6 [Formula 8] Mz=-C3+C4-C7+C8

[0131] When [Equation 7] and [Equation 8] are used, the detection element 60 can be configured with four displacement electrode substrates, and displacement beams 42 other than those on which these four displacement electrode substrates are provided do not need to be provided with displacement electrode substrates. This makes it possible to reduce the number of displacement electrode substrates and fixed electrode substrates. Displacement beams 42 on which no displacement electrode substrate is provided can be omitted, thereby reducing the number of displacement beams 42.

[0132] In Equation 7, when moment Mz acts, the first displacement electrode substrate Ed1 constituting the first capacitance element C1 moves away from the opposing first fixed electrode substrate Ef1, and the second displacement electrode substrate Ed2 constituting the second capacitance element C2 moves closer to the opposing second fixed electrode substrate Ef2. The fifth displacement electrode substrate Ed5 constituting the fifth capacitance element C5 moves away from the opposing fifth fixed electrode substrate Ef5, and the sixth displacement electrode substrate Ed6 constituting the sixth capacitance element C6 moves closer to the opposing sixth fixed electrode substrate Ef6. This makes it possible to prevent fluctuations in capacitance value due to temperature changes of the capacitance elements, as well as fluctuations in capacitance value due to common-mode noise.

[0133] In Equation 8, when moment Mz acts, the third displacement electrode substrate Ed3 constituting the third capacitance element C3 moves away from the opposing third fixed electrode substrate Ef3, and the fourth displacement electrode substrate Ed4 constituting the fourth capacitance element C4 moves closer to the opposing fourth fixed electrode substrate Ef4. The seventh displacement electrode substrate Ed7 constituting the seventh capacitance element C7 moves away from the opposing seventh fixed electrode substrate Ef7, and the eighth displacement electrode substrate Ed8 constituting the eighth capacitance element C8 moves closer to the opposing eighth fixed electrode substrate Ef8. This makes it possible to prevent fluctuations in capacitance value due to temperature changes of the capacitance elements, as well as fluctuations in capacitance value due to common-mode noise.

[0134] Fault diagnosis may be performed by calculating the moment Mz using both [Equation 7] and [Equation 8] and comparing them.

[0135] In addition to the above-mentioned [Equation 7] and [Equation 8], the moment Mz can also be calculated using the following equation.

[0136] [Formula 9] Mz=-C1+C4-C5+C6 [Formula 10] Mz=C2-C3+C6-C7

[0137] In this case, too, the number of displacement electrode substrates and the number of fixed electrode substrates can be reduced. Displacement beams 42 that are not provided with displacement electrode substrates can be omitted, thereby reducing the number of displacement beams 42. As with [Equation 7] and [Equation 8], [Equation 9] and [Equation 10] can also prevent fluctuations in the capacitance value due to temperature changes in the capacitive element, and can also prevent fluctuations in the capacitance value due to common-mode noise. Fault diagnosis may be performed by calculating the moment Mz using both [Equation 9] and [Equation 10] above and comparing them.

[0138] 9 does not elastically deform in response to forces or moments due to axial components other than the moment Mz. As a result, the moment Mz may be calculated using only one of the first capacitive element C1 to the eighth capacitive element C8. Alternatively, the moment Mz may be calculated using any two of the first capacitive element C1 to the eighth capacitive element C8.

[0139] For example, the moment Mz may be calculated using a combination of capacitance elements such as -C1+C2, -C3+C4, -C5+C6, -C7+C8, or -C1+C4, C2-C5, -C3+C6, C4-C7, -C5+C8, C6-C7, etc.

[0140] In this case, the detection element 60 can be configured with two displacement electrode substrates, and displacement beams 42 other than those provided with these two displacement electrode substrates may not be provided with displacement electrode substrates. This makes it possible to reduce the number of displacement electrode substrates and fixed electrode substrates. Displacement beams 42 that are not provided with a displacement electrode substrate can be omitted, thereby reducing the number of displacement beams 42. Furthermore, as with [Equation 7] and [Equation 8], it is possible to prevent fluctuations in the capacitance value due to temperature changes in the capacitive element, and it is also possible to prevent fluctuations in the capacitance value due to common-mode noise.

[0141] As described above, according to the present embodiment, the dimension in the third direction of elastically deformable body 41 of strain generating bodies 40A to 40D is greater than the dimension in the second direction of elastically deformable body 41. This increases rigidity against a force in the third direction, and prevents elastic deformation of elastically deformable body 41 in the third direction. Therefore, even when force Fx in the X-axis direction and force Fy in the Y-axis direction act on force receiving body 20, elastic deformation of elastically deformable body 41 can be prevented. This increases rigidity against forces Fx and Fy, and improves the reliability of force sensor 10.

[0142] (Third embodiment) Next, a force sensor according to a third embodiment of the present invention will be described with reference to FIGS.

[0143] 11 to 13, the third embodiment is different from the second embodiment shown in Figures 8 to 10 in that the displacement body protrudes in the second direction from the elastically deformable body on one side thereof and does not protrude on the other side thereof, and other configurations are substantially the same as those of the second embodiment shown in Figures 8 to 10. In Figures 11 to 13, the same parts as those of the second embodiment shown in Figures 8 to 10 are designated by the same reference numerals and detailed description thereof will be omitted.

[0144] 11 and 12, in this embodiment, the displacement beam 42 of each of the strain bodies 40A to 40D protrudes in the second direction from the elastic deformation body 41 on one side of the elastic deformation body 41. On the other side of the elastic deformation body 41, the displacement beam 42 does not protrude and is not present. FIG. 11 is a cross-sectional view showing a force sensor 10 according to the third embodiment. FIG. 12 is a plan view showing the force sensor 10 shown in FIG. 11.

[0145] The displacement beam 42 of the first flexure body 40A and the displacement beam 42 of the second flexure body 40B face each other. That is, the displacement beam 42 of the first flexure body 40A is disposed on the side of the second flexure body 40B with respect to the elastic deformation body 41 of the first flexure body 40A. The displacement beam 42 of the second flexure body 40B is disposed on the side of the first flexure body 40A with respect to the elastic deformation body 41 of the second flexure body 40B. More specifically, the displacement beam 42 of the first flexure body 40A is disposed on the positive side of the elastic deformation body 41 of the first flexure body 40A in the X-axis direction, and the displacement beam 42 of the second flexure body 40B is disposed on the negative side of the elastic deformation body 41 of the second flexure body 40B in the Y-axis direction. As a result, the displacement beam 42 of the first flexure body 40A and the displacement beam 42 of the second flexure body 40B face each other.

[0146] Similarly, the displacement beam 42 of the third flexure body 40C and the displacement beam 42 of the fourth flexure body 40D face each other. That is, the displacement beam 42 of the third flexure body 40C is disposed on the side of the fourth flexure body 40D relative to the elastic deformation body 41 of the third flexure body 40C. The displacement beam 42 of the fourth flexure body 40D is disposed on the side of the third flexure body 40C relative to the elastic deformation body 41 of the fourth flexure body 40D. More specifically, the displacement beam 42 of the third flexure body 40C is disposed on the negative side of the elastic deformation body 41 of the third flexure body 40C in the X axis direction, and the displacement beam 42 of the fourth flexure body 40D is disposed on the positive side of the elastic deformation body 41 of the fourth flexure body 40D in the Y axis direction. As a result, the displacement beam 42 of the third flexure body 40C and the displacement beam 42 of the fourth flexure body 40D face each other.

[0147] A plurality of displacement electrode substrates are provided on each displacement beam 42. The plurality of displacement electrode substrates are aligned in a third direction perpendicular to the second direction. Fixed electrode substrates are provided on the support 30 so as to face each of the displacement electrode substrates.

[0148] As shown in FIGS. 11 and 12 , the detection element 60 according to this embodiment includes two fixed electrode substrates Ef21 and Ef22 and two displacement electrode substrates Ed21 and Ed22 as electrodes for the first flexure body 40A. The displacement electrode substrates Ed21 and Ed22 are disposed on the displacement beam 42 of the first flexure body 40A. The two displacement electrode substrates Ed21 and Ed22 may be disposed at the end of the displacement beam 42 on the positive side in the X-axis direction. The two displacement electrode substrates Ed21 and Ed22 are disposed at the same position in the X-axis direction but at different positions in the Y-axis direction. The displacement electrode substrate Ed21 is disposed closer to the center of the force sensor 10 than the displacement electrode substrate Ed22 in a plan view. More specifically, the displacement electrode substrate Ed21 is disposed on the positive side in the Y-axis direction than the displacement electrode substrate Ed22. The displacement electrode substrate Ed21 is disposed on the negative side in the Y-axis direction than the displacement electrode substrate Ed22.

[0149] The fixed electrode substrate Ef21 faces the displacement electrode substrate Ed21. The fixed electrode substrate Ef21 and the displacement electrode substrate Ed21 form a 21st capacitance element C21. The fixed electrode substrate Ef22 faces the displacement electrode substrate Ed22. The fixed electrode substrate Ef22 and the displacement electrode substrate Ed22 form a 22nd capacitance element C22. The 21st capacitance element C21 and the 22nd capacitance element C22 form a detection element 60 for the first strain generating body 40A.

[0150] The configuration of the first flexure body 40A and the corresponding detection element 60 can be similarly applied to the second flexure body 40B, the third flexure body 40C, and the fourth flexure body 40D.

[0151] 11 and 12, the detection element 60 includes two fixed electrode substrates Ef31 and Ef32 and two displacement electrode substrates Ed31 and Ed32 as electrodes for the second flexure body 40B. The displacement electrode substrates Ed31 and Ed32 are arranged on the displacement beam 42 of the second flexure body 40B. The two displacement electrode substrates Ed31 and Ed32 may be arranged at the end of the displacement beam 42 on the negative side in the Y axis direction. The displacement electrode substrate Ed31 is arranged on the negative side in the X axis direction relative to the displacement electrode substrate Ed32 and inside the force sensor 10 in a plan view.

[0152] The fixed electrode substrate Ef31 faces the displacement electrode substrate Ed31. The fixed electrode substrate Ef31 and the displacement electrode substrate Ed31 form a 31st capacitance element C31. The fixed electrode substrate Ef32 faces the displacement electrode substrate Ed32. The fixed electrode substrate Ef32 and the displacement electrode substrate Ed32 form a 32nd capacitance element C32. The 31st capacitance element C31 and the 32nd capacitance element C32 form a detection element 60 for the second strain generating body 40B.

[0153] 11 and 12, the detection element 60 includes two fixed electrode substrates Ef61 and Ef62 and two displacement electrode substrates Ed61 and Ed62 as electrodes for the third flexure body 40C. The displacement electrode substrates Ed61 and Ed62 are arranged on the displacement beam 42 of the third flexure body 40C. The two displacement electrode substrates Ed61 and Ed62 may be arranged at the end of the displacement beam 42 on the negative side in the X-axis direction. The displacement electrode substrate Ed61 is arranged on the negative side in the Y-axis direction relative to the displacement electrode substrate Ed62 and inside the force sensor 10 in a plan view.

[0154] The fixed electrode substrate Ef61 faces the displacement electrode substrate Ed61. The fixed electrode substrate Ef61 and the displacement electrode substrate Ed61 form a 61st capacitance element C61. The fixed electrode substrate Ef62 faces the displacement electrode substrate Ed62. The fixed electrode substrate Ef62 and the displacement electrode substrate Ed62 form a 62nd capacitance element C62. The 61st capacitance element C61 and the 62nd capacitance element C62 form a detection element 60 for the third strain generating body 40C.

[0155] 11 and 12, the detection element 60 includes two fixed electrode substrates Ef71 and Ef72 and two displacement electrode substrates Ed71 and Ed72 as electrodes for the fourth flexure body 40D. The displacement electrode substrates Ed71 and Ed72 are arranged on the displacement beam 42 of the fourth flexure body 40D. The two displacement electrode substrates Ed71 and Ed72 may be arranged at the end of the displacement beam 42 on the positive side in the Y-axis direction. The displacement electrode substrate Ed71 is arranged on the positive side in the X-axis direction relative to the displacement electrode substrate Ed72 and inside the force sensor 10 in a plan view.

[0156] The fixed electrode substrate Ef71 faces the displacement electrode substrate Ed71. The fixed electrode substrate Ef71 and the displacement electrode substrate Ed71 form a 71st capacitance element C71. The fixed electrode substrate Ef72 faces the displacement electrode substrate Ed72. The fixed electrode substrate Ef72 and the displacement electrode substrate Ed72 form a 72nd capacitance element C72. The 71st capacitance element C71 and the 72nd capacitance element C72 form the detection element 60 for the fourth strain generating body 40D.

[0157] Force sensor 10 according to the present embodiment can detect moment Mz, similar to force sensor 10 shown in Figures 8 and 9. When moment Mz acts on force receiving member 20, a change in the capacitance value of each of capacitance elements C21 to C72 is detected, and the direction and magnitude of moment Mz acting on force receiving member 20 are detected. Then, as shown in Figure 13, the capacitance value of each of capacitance elements C21 to C72 changes. Figure 13 is a table showing the change in the capacitance value of each of capacitance elements C21 to C72.

[0158] 13, moment Mz acting on force receiving member 20 can be calculated using the following equation, similar to the above-mentioned [Equation 10]. Moment Mz can be calculated using the following [Equation 11] and [Equation 12].

[0159] [Formula 11] Mz=C21-C31+C61-C71 [Formula 12] Mz=C22-C32+C62-C72

[0160] Fault diagnosis may be performed by calculating the moment Mz using both [Equation 11] and [Equation 12] and comparing them. As described in the second embodiment, the moment Mz may be calculated using any two of the capacitance elements C21, C31, C61, and C71, or any two of the capacitance elements C22, C32, C62, and C72. For example, the moment Mz may be calculated using a combination of capacitance elements such as +C21-C31, +C61-C71, -C31+C61, +C21-C71, +C22-C32, +C62-C72, -C32+C62, and +C22-C72. In this case, the detection element 60 may be composed of two displacement electrode substrates, and displacement beams 42 other than the displacement beams 42 on which these two displacement electrode substrates are provided may not be provided with displacement electrode substrates. This allows the number of displacement electrode substrates and the number of fixed electrode substrates to be reduced. Displacement beams 42 that are not provided with displacement electrode substrates can be omitted, thereby reducing the number of displacement beams 42. Furthermore, it is possible to prevent fluctuations in the capacitance value due to temperature changes of the capacitance element, and to prevent fluctuations in the capacitance value due to common-mode noise.

[0161] As described above, according to this embodiment, the displacement beam 42 protrudes in the second direction on one side of the elastically deformable body 41 of each of the strain-generating bodies 40A to 40D, and does not protrude on the other side. A displacement electrode substrate is disposed on each of the displacement beams 42, and a fixed electrode substrate facing the corresponding displacement electrode substrate is disposed on the support body 30. This makes it possible to change the inter-electrode distance between the displacement electrode substrate and the corresponding fixed electrode substrate when the elastically deformable body 41 elastically deforms in the second direction. This improves detection sensitivity.

[0162] Furthermore, according to the present embodiment, the number of displacement beams 42 of the flexure bodies 40A to 40D can be reduced. This allows the structures of the flexure bodies 40A to 40D to be simplified. In this case, the force sensor 10 can be made cheaper.

[0163] 8 to 10, elastic deformation of elastic deformable body 41 can be suppressed even when force Fx in the X-axis direction and force Fy in the Y-axis direction act on force receiving body 20. This increases the rigidity against forces Fx and Fy, improving the reliability of force sensor 10.

[0164] Furthermore, according to this embodiment, each displacement beam 42 is provided with a plurality of displacement electrode substrates Ed21 to Ed72, and the support body 30 is provided with fixed electrode substrates Ef21 to Ef72 facing the respective displacement electrode substrates Ed21 to Ed72. This makes it possible to perform fault diagnosis using the moment Mz calculated from the change in capacitance value of the capacitance elements C21, C31, C61, and C71 including the displacement electrode substrates Ed21, Ed31, Ed61, and Ed71 on one side of each displacement beam 42, and the moment Mz calculated from the change in capacitance value of the capacitance elements C22, C32, C62, and C72 including the displacement electrode substrates Ed22, Ed32, Ed62, and Ed72 on the other side. This improves the reliability of the force sensor 10.

[0165] Furthermore, according to this embodiment, the displacement beams 42 of the first flexure body 40A and the displacement beams 42 of the second flexure body 40B face each other. The displacement beams 42 of the third flexure body 40C and the displacement beams 42 of the fourth flexure body 40D face each other. This improves the efficiency of connecting electrical wiring to the displacement electrode substrates Ed21-Ed72 and the fixed electrode substrates Ef21-Ef72.

[0166] In the above-described embodiment, an example has been described in which two displacement electrode substrates Ed21 to Ed72 are provided on each displacement beam 42. However, this is not limiting. For example, as described above, the two displacement electrode substrates provided on each displacement beam 42 may be integrated into a single displacement electrode substrate. In this case, the two fixed electrode substrates facing one displacement electrode substrate may be formed separately and spaced apart from each other. Alternatively, the two fixed electrode substrates facing each displacement beam 42 may be integrated into a single fixed electrode substrate. In this case, the two displacement electrode substrates facing one fixed electrode substrate may be formed separately and spaced apart from each other.

[0167] (Fourth embodiment) Next, a force sensor according to a fourth embodiment of the present invention will be described with reference to FIG.

[0168] The fourth embodiment shown in Fig. 14 differs mainly in that the force receiving body includes a first force receiving body opening separating the force receiving body side end of the first strain body from the force receiving body side end of the second strain body, and a second force receiving body opening separating the force receiving body side end of the third strain body from the force receiving body side end of the fourth strain body, and the other configurations are substantially the same as those of the third embodiment shown in Fig. 11 to Fig. 13. In Fig. 14, the same parts as those of the third embodiment shown in Fig. 11 to Fig. 13 are designated by the same reference numerals and detailed description thereof will be omitted.

[0169] As shown in Fig. 14, in the present embodiment, force receiving body 20 may include first force receiving body opening 21 and second force receiving body opening 22. Fig. 14 is a perspective view showing force sensor 10 according to the fourth embodiment.

[0170] The first force receiving body opening 21 is formed to separate the force receiving body side end 43 of the first flexure body 40A from the force receiving body side end 43 of the second flexure body 40B. As a result, the force receiving body side end 43 of the first flexure body 40A and the force receiving body side end 43 of the second flexure body 40B are not connected by a member that constitutes the force receiving body 20 and are separated from each other. When viewed from the positive side in the Z axis direction, the displacement beam 42 of the first flexure body 40A, the displacement beam 42 of the second flexure body 40B, and a first support connecting portion 33, which will be described later, are exposed from the first force receiving body opening 21.

[0171] The second force receiving body opening 22 is formed to separate the force receiving body side end 43 of the third flexure body 40C from the force receiving body side end 43 of the fourth flexure body 40D. As a result, the force receiving body side end 43 of the third flexure body 40C and the force receiving body side end 43 of the fourth flexure body 40D are not connected by a member constituting the force receiving body 20 and are separated from each other. When viewed from the positive side in the Z axis direction, the displacement beam 42 of the third flexure body 40C, the displacement beam 42 of the fourth flexure body 40D, and a second support body connection portion 34, which will be described later, are exposed from the second force receiving body opening 22.

[0172] The force receiving body 20 may include a first force receiving body connecting portion 23 and a second force receiving body connecting portion 24. The first force receiving body connecting portion 23 connects the force receiving body side end portion 43 of the second flexure body 40B to the force receiving body side end portion 43 of the third flexure body 40C. The second force receiving body connecting portion 24 connects the force receiving body side end portion 43 of the fourth flexure body 40D to the force receiving body side end portion 43 of the first flexure body 40A. When the force receiving body 20 includes the force receiving body central opening 20a, the planar shape of the first force receiving body connecting portion 23 and the second force receiving body connecting portion 24 may be roughly 1 / 4 of a circular ring shape.

[0173] Bolt holes 25 may be provided in first force receiving body connection portion 23 and second force receiving body connection portion 24. Bolt holes 25 may be used to attach tool 3 shown in FIG. 1 or an end effector (not shown).

[0174] As shown in FIG. 14, in this embodiment, the support 30 may include a first support opening 31 and a second support opening 32.

[0175] The first support opening 31 is formed to separate the support-side end 44 of the second flexure body 40B from the support-side end 44 of the third flexure body 40C. As a result, the support-side end 44 of the second flexure body 40B and the support-side end 44 of the third flexure body 40C are not connected by a member constituting the support 30 and are separated from each other. When viewed from the Z-axis direction negative side, the first force receiving body connecting portion 23 described above is exposed from the first support opening 31.

[0176] The second support opening 32 is formed to separate the support-side end 44 of the fourth flexure body 40D from the support-side end 44 of the first flexure body 40A. As a result, the support-side end 44 of the fourth flexure body 40D and the support-side end 44 of the first flexure body 40A are not connected by a member constituting the support 30 and are separated from each other. When viewed from the Z-axis direction negative side, the second force receiving member connecting portion 24 described above is exposed from the second support opening 32.

[0177] 14, in this embodiment, the support 30 may include a first support connecting portion 33 and a second support connecting portion 34. The first support connecting portion 33 connects the support-side end portion 44 of the first flexure body 40A to the support-side end portion 44 of the second flexure body 40B. The second support connecting portion 34 connects the support-side end portion 44 of the third flexure body 40C to the support-side end portion 44 of the fourth flexure body 40D. When the support 30 includes the support central opening 30a, the planar shape of the first support connecting portion 33 and the planar shape of the second support connecting portion 34 may be roughly a quarter of a circular ring shape.

[0178] The first support connecting portion 33 and the second support connecting portion 34 may be provided with bolt holes 35. The bolt holes 35 may be used for attachment to the robot arm 4 shown in FIG.

[0179] The flexure bodies 40A to 40D shown in Fig. 14 may be configured similarly to the flexure bodies 40A to 40D shown in Fig. 11 and Fig. 12. The detection element 60 may also be configured similarly to the detection element 60 shown in Fig. 11 and Fig. 12. In this case, the direction and magnitude of the moment Mz acting on the force sensor 10 can be detected in the same manner, thereby improving detection sensitivity. In Fig. 14, the capacitive elements C1 to C8 are omitted to clarify the drawing.

[0180] As described above, according to the present embodiment, the force receiving body 20 includes the first force receiving body opening 21 separating the force receiving body side end 43 of the first flexure body 40A from the force receiving body side end 43 of the second flexure body 40B, and the second force receiving body opening 22 separating the force receiving body side end 43 of the third flexure body 40C from the force receiving body side end 43 of the fourth flexure body 40D. This reduces the mass of the force receiving body 20, thereby improving the handleability of the force sensor 10.

[0181] Furthermore, according to this embodiment, the support body 30 includes a first support body opening 31 that separates the support body side end 44 of the second flexure body 40B from the support body side end 44 of the third flexure body 40C, and a second support body opening 32 that separates the support body side end 44 of the fourth flexure body 40D from the support body side end 44 of the first flexure body 40A. This reduces the mass of the support body 30, thereby improving the handleability of the force sensor 10.

[0182] (Fifth embodiment) Next, a force sensor according to a fifth embodiment of the present invention will be described with reference to FIGS.

[0183] In the fifth embodiment shown in Figures 15 to 20, the force receiving body is different mainly in that it includes a force receiving body main body portion and a force receiving body thin portion that is thinner than the force receiving body main body portion, and other configurations are substantially the same as those of the first embodiment shown in Figures 1 to 7. In Figures 15 to 20, the same parts as those in the first embodiment shown in Figures 1 to 7 are designated by the same reference numerals and detailed description thereof will be omitted.

[0184] As shown in FIGS. 15 and 16 , force receiver 20 according to the present embodiment includes force receiver main body 26 and force receiver thin portion 27. Force receiver main body 26 is a relatively thick portion of force receiver 20. Force receiver thin portion 27 is a portion thinner than force receiver main body 26. Force receiver thin portion 27 is flexible and can be elastically deformed by the action of a force in the Z-axis direction. The spring constant of force receiver thin portion 27 with respect to the action of a force in the Z-axis direction is smaller than the spring constant of force receiver main body 26 with respect to the action of a force in the Z-axis direction. The planar shape of force receiver thin portion 27 may be circular or rectangular, and is optional. As shown in FIG. 16 , the planar shape of force receiver thin portion 27 may be approximately circular. FIG. 15 is a cross-sectional view showing a force sensor 10 according to a fifth embodiment. FIG. 16 is a plan view showing the force sensor 10 shown in FIG. 15 .

[0185] In the Z-axis direction, the surface of force receiver thin portion 27 facing support body 30 may be formed at the same position as the surface of force receiver main body portion 26 facing support body 30. In this case, the surface of force receiver main body portion 26 and the surface of force receiver thin portion 27 may form a continuous surface. The surface of force receiver thin portion 27 opposite support body 30 is positioned closer to support body 30 than the surface of force receiver main body portion 26 opposite support body 30. As a result, a recess 28 is formed on the surface of force receiver 20 opposite support body 30.

[0186] The force receiver thin portion 27 is connected to the force receiver side end portion 43 of the strain generators 40A to 40D. The force receiver 20 includes four force receiver thin portions 27. Each force receiver thin portion 27 is arranged at a position overlapping the elastic deformation body 41 of the corresponding strain generator 40A to 40D in a plan view. The force receiver side end portion 43 of the corresponding elastic deformation body 41 may be arranged at the center of each force receiver thin portion 27. The force receiver thin portions 27 are separated from each other and are not connected to each other. One or more through holes (not shown) may be formed in the force receiver thin portion 27. The through holes are holes that pass through the force receiver thin portion 27. The through holes may be arranged at positions that do not overlap the force receiver side end portion 43 in a plan view. The formation of the through holes can increase the flexibility of the force receiver thin portion 27.

[0187] As shown in Figures 15 and 16, the support body 30 according to this embodiment includes a support body main body portion 36 and a support body thin portion 37. The support body main body portion 36 is a relatively thick portion of the support body 30. The support body thin portion 37 is a portion thinner than the support body main body portion 36. The support body thin portion 37 is flexible and can be elastically deformed by the action of a force in the Z-axis direction. The spring constant of the support body thin portion 37 with respect to the action of a force in the Z-axis direction is smaller than the spring constant of the support body main body portion 36 with respect to the action of a force in the Z-axis direction. The planar shape of the support body thin portion 37 may be circular or rectangular, and is arbitrary. The planar shape of the support body thin portion 37 may be roughly circular, similar to the force receiving body thin portion 27 described above.

[0188] In FIG. 16, the planar shape of the elastically deformable body 41 is generally circular, but is not limited to this.

[0189] In the Z-axis direction, the surface of support body thin portion 37 facing force receiving body 20 may be formed at the same position as the surface of support body main portion 36 facing force receiving body 20. In this case, the surface of support body main portion 36 and the surface of support body thin portion 37 may form a continuous surface. The surface of support body thin portion 37 opposite force receiving body 20 is positioned closer to force receiving body 20 than the surface of support body main portion 36 opposite force receiving body 20. As a result, a recess 38 is formed on the surface of support body 30 opposite force receiving body 20.

[0190] The support thin portion 37 is connected to the support side end portion 44 of the flexure bodies 40A to 40D. The support body 30 includes four support thin portions 37. Each support thin portion 37 is arranged at a position overlapping the elastic deformation body 41 of the corresponding flexure body 40A to 40D in a plan view. The support side end portion 44 of the corresponding elastic deformation body 41 may be arranged at the center of each support thin portion 37. The support thin portions 37 are separated from each other and are not connected to each other. One or more through holes (not shown) may be formed in the support thin portion 37. The through holes are holes that pass through the support thin portion 37. The through holes may be arranged at positions that do not overlap the support side end portion 44 in a plan view. By forming the through holes, the flexibility of the support thin portion 37 can be increased.

[0191] Next, a method for detecting a force or moment in the force sensor according to this embodiment having the above configuration will be described.

[0192] When a force Fx in the X-axis direction acts on the first flexure body 40A alone according to this embodiment, the capacitance value of the first capacitance element C1 decreases and the capacitance value of the second capacitance element C2 increases, similar to the first flexure body 40A shown in Fig. 6. In this case, the force Fx is expressed by the above-mentioned [Equation 1].

[0193] When a moment My about the Y-axis acts on the first flexure body 40A according to this embodiment, the capacitance value of the first capacitance element C1 decreases and the capacitance value of the second capacitance element C2 increases, similar to the first flexure body 40A shown in Fig. 6. In this case, the moment My is expressed by the above-mentioned [Equation 2].

[0194] When a force Fy in the Y-axis direction acts on the first flexure body 40A alone according to this embodiment, it can be considered that there is no change in the capacitance value of each of the capacitance elements C1 and C2, similar to the first flexure body 40A shown in Fig. 6. Similarly, when a moment Mx about the X-axis acts, it can be considered that there is no change in the capacitance value of each of the capacitance elements C1 and C2.

[0195] A case where a force Fz in the Z-axis direction acts on the first flexure body 40A alone according to this embodiment will be described with reference to Figs. 17 and 18. Fig. 17 is a front view schematically showing the deformation state of the first flexure body 40A when the force receiving body 20 receives the force Fz on the positive side in the Z-axis direction. Fig. 18 is a front view schematically showing the deformation state of the first flexure body 40A when the force receiving body 20 receives the force Fz on the negative side in the Z-axis direction.

[0196] When a force Fz acts on the first flexure body 40A in the positive Z-axis direction, the force receiving body thin portion 27 and the support thin portion 37 elastically deform, as shown in FIG. 17. In this case, the force receiving body 20 is displaced in the positive Z-axis direction, and the elastic deformation body 41 and displacement beam 42 of the first flexure body 40A are displaced in the positive Z-axis direction. The elastic deformation body 41 does not elastically deform in the Z-axis direction. As a result, the first displacement electrode substrate Ed1 rises and moves away from the first fixed electrode substrate Ef1. The inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 increases, and the capacitance value of the first capacitance element C1 decreases. Similarly, the second displacement electrode substrate Ed2 rises and moves away from the second fixed electrode substrate Ef2. The inter-electrode distance between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 increases, and the capacitance value of the second capacitance element C2 decreases.

[0197] The force Fz acting on the mass of the first strain element 40A can be calculated by the following formula. [Formula 13] Fz=-C1-C2

[0198] On the other hand, when a force Fz acts on the first flexure body 40A in the negative Z-axis direction, the force receiving body thin portion 27 and the support thin portion 37 elastically deform, as shown in FIG. 18. In this case, the force receiving body 20 is displaced in the negative Z-axis direction, and the elastic deformation body 41 and displacement beam 42 of the first flexure body 40A are displaced in the negative Z-axis direction. The elastic deformation body 41 does not elastically deform in the Z-axis direction. As a result, the first displacement electrode substrate Ed1 descends and approaches the first fixed electrode substrate Ef1. The inter-electrode distance (distance in the Z-axis direction) between the first displacement electrode substrate Ed1 and the first fixed electrode substrate Ef1 decreases, and the capacitance value of the first capacitance element C1 increases. Similarly, the second displacement electrode substrate Ed2 descends and approaches the second fixed electrode substrate Ef2. The inter-electrode distance between the second displacement electrode substrate Ed2 and the second fixed electrode substrate Ef2 decreases, and the capacitance value of the second capacitance element C2 increases.

[0199] In this way, the force sensor 10 in which the force receiving body 20 and the support body 30 are connected only by the first strain body 40A can detect the force Fx, the force Fz, and the moment My. This force sensor 10 may be used in an environment in which only one of the force Fx and the moment My acts.

[0200] Next, changes in the capacitance values ​​of the capacitance elements C1 to C8 when a force Fz in the Z-axis direction, a moment Mx about the X-axis, and a moment My about the Y-axis are applied to the force receiving body 20 of the force sensor 10 shown in Figures 15 and 16 will be described using Figure 19. The changes in the capacitance values ​​of the capacitance elements C1 to C8 when a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a moment Mz about the Z-axis are applied are similar to the changes in the capacitance values ​​in the force sensor 10 shown in Figure 5. Therefore, a detailed description of the force Fx, the force Fy, and the moment Mz will be omitted. Figure 19 is a table showing the changes in the capacitance values ​​of the capacitance elements C1 to C8.

[0201] (When +Fz is applied) A case where force Fz acts on force receiving member 20 in the positive direction of the Z axis will be described.

[0202] In this case, the first strain generating body 40A is elastically deformed as shown in Fig. 17, and the capacitance value of the first capacitance element C1 decreases, and the capacitance value of the second capacitance element C2 decreases. This is indicated by "- (minus)" next to C1 and C2 in the row of Fz in the table shown in Fig. 19.

[0203] The second flexure body 40B elastically deforms in the same manner as the first flexure body 40A shown in Fig. 17. As a result, the capacitance value of the third capacitance element C3 decreases, and the capacitance value of the fourth capacitance element C4 decreases. The third flexure body 40C and the fourth flexure body 40D also elastically deform, and the capacitance values ​​of the fifth capacitance element C5 to the eighth capacitance element C8 decrease.

[0204] (When +Mx is applied) A case where moment Mx about the X axis acts on force receiving member 20 will be described.

[0205] In this case, the first flexure body 40A is elastically deformed in the same manner as the first flexure body 40A shown in FIG. 18, and the capacitance value of the first capacitance element C1 increases, and the capacitance value of the second capacitance element C2 also increases.

[0206] In the second flexure body 40B, the elastic deformation body 41 is located at the same position as the center O of the force receiving body 20 in the Y-axis direction, so the displacement of the displacement beam 42 of the second flexure body 40B is smaller than the displacement of the displacement beam 42 of the first flexure body 40A and the displacement of the displacement beam 42 of the third flexure body 40C. Here, for simplicity of explanation, it is assumed that the displacement beam 42 of the second flexure body 40B does not displace. Therefore, the capacitance value of the third capacitance element C3 does not change, and the capacitance value of the fourth capacitance element C4 does not change either.

[0207] The third flexure body 40C is elastically deformed in the same manner as the first flexure body 40A shown in FIG. 17, and the capacitance value of the fifth capacitance element C5 decreases, and the capacitance value of the sixth capacitance element C6 decreases.

[0208] In the fourth flexure body 40D, the elastic deformation body 41 is located at the same position as the center O of the force receiving body 20 in the Y-axis direction, so the displacement of the displacement beam 42 of the fourth flexure body 40D is smaller than the displacement of the displacement beam 42 of the first flexure body 40A and the displacement of the displacement beam 42 of the third flexure body 40C. Here, for simplicity of explanation, it is assumed that the displacement beam 42 of the fourth flexure body 40D does not displace. Therefore, the capacitance value of the seventh capacitance element C7 does not change, and the capacitance value of the eighth capacitance element C8 does not change either.

[0209] (When +My is applied) A case where a moment My about the Y axis acts on force receiving member 20 will be described.

[0210] In this case, in the first flexure body 40A, the elastic deformation body 41 is located at the same position as the center O of the force receiving body 20 in the X-axis direction, so the displacement of the displacement beam 42 of the first flexure body 40A is smaller than the displacement of the displacement beam 42 of the second flexure body 40B and the displacement of the displacement beam 42 of the fourth flexure body 40D. Here, to simplify the explanation, it is assumed that the displacement beam 42 of the first flexure body 40A does not displace. Therefore, the capacitance value of the first capacitance element C1 does not change, and the capacitance value of the second capacitance element C2 does not change either.

[0211] The second flexure body 40B elastically deforms in the same manner as the first flexure body 40A shown in FIG. 18, and the capacitance value of the third capacitance element C3 increases, and the capacitance value of the fourth capacitance element C4 also increases.

[0212] In the third flexure body 40C, the elastic deformation body 41 is located at the same position as the center O of the force receiving body 20 in the X-axis direction, so the displacement of the displacement beam 42 of the third flexure body 40C is smaller than the displacement of the displacement beam 42 of the second flexure body 40B and the displacement of the displacement beam 42 of the fourth flexure body 40D. Here, to simplify the explanation, it is assumed that the displacement beam 42 of the third flexure body 40C does not displace. Therefore, the capacitance value of the fifth capacitance element C5 does not change, and the capacitance value of the sixth capacitance element C6 does not change either.

[0213] The fourth flexure body 40D elastically deforms in the same manner as the first flexure body 40A shown in FIG. 17, and the capacitance value of the seventh capacitance element C7 decreases, and the capacitance value of the eighth capacitance element C8 decreases.

[0214] In this way, force sensor 10 according to the present embodiment can detect force Fx, force Fy, force Fz, moment Mx, moment My, and moment Mz, and can detect six-axis components. When force Fx, force Fy, force Fz, moment Mx, moment My, or moment Mz acts on force receiving member 20, a change in the capacitance value of each of capacitance elements C1 to C8 is detected, and the direction and magnitude of the force or moment acting on force receiving member 20 are detected. Then, as shown in FIG. 19 , the capacitance value of each of capacitance elements C1 to C8 changes.

[0215] 19, force Fx, force Fy, force Fz, moment Mx, moment My, and moment Mz acting on force receiving member 20 can be calculated using the following equations. This makes it possible to detect the six-axis components of the force. [Formula 14] Fx=-C1+C2 +C5-C6 [Formula 15] Fy= -C3+C4 +C7-C8 [Formula 16] Fz=-C1-C2-C3-C4-C5-C6-C7-C8 [Formula 17] Mx= C1+C2 -C5-C6 [Formula 18] My= C3+C4 -C7-C8 [Formula 19] Mz=-C1+C2-C3+C4-C5+C6-C7+C8

[0216] As described above, the force sensor 10 shown in Figures 15 and 16 can detect the force Fx, force Fy, force Fz, moment Mx, moment My, and moment Mz as shown in [Equation 14] to [Equation 19] above, and is therefore capable of detecting six-axis components of force. However, the number of axial components of force that the force sensor 10 can detect is not limited to six, and any axial components can be detected depending on the number, structure, and shape of the strain-generating bodies. Although a detailed description will be omitted, for example, six-axis components of force and moment can also be detected by using three strain-generating bodies.

[0217] Applying the changes in capacitance value of each of capacitance elements C1 to C8 shown in Fig. 19 to the above-mentioned [Equation 14] to [Equation 19], a table showing the main axis sensitivity and other axis sensitivity in Fig. 20 is obtained. Fig. 20 is a table showing the main axis sensitivity and other axis sensitivity based on the changes in capacitance value shown in Fig. 19. In Fig. 20, VFx is the output when a force Fx in the X-axis direction is applied, VFy is the output when a force Fy in the Y-axis direction is applied, and VFz is the output when a force Fz in the Z-axis direction is applied. Furthermore, VMx is the output when a moment Mx about the X-axis is applied, VMy is the output when a moment My about the Y-axis is applied, and VMz is the output when a moment Mz about the Z-axis is applied.

[0218] The numerical values ​​shown in the table of FIG. 20 are obtained by substituting the capacitive elements marked with a "+" sign for "+1" and the capacitive elements marked with a "-" sign for "-1" into the right-hand sides of the above-mentioned [Equations 14] to [Equations 19] for the forces Fx, Fy, and Fz and the moments Mx, My, and Mz listed in the table of FIG. 19. For example, the numerical value "4" in the square where the column for Fx and the row for VFx intersect is obtained by substituting "+1" for C2 and C5 and "-1" for C1 and C6 in [Equation 14] representing Fx, based on the row for Fx in FIG. 19. Furthermore, the numerical value "0" in the square where the column for Fx and the row for VFy intersect is obtained by substituting 0 for C1, C2, C5, and C6 in [Equation 14] representing Fx, based on the row for Fy in FIG. 19.

[0219] As shown in FIG. 20, for the force Fx, VFx has a value of "4," but VFy, VFz, VMx, VMy, and VMz have values ​​of "0." This means that for the force Fx, there is no other-axis sensitivity and only the main-axis sensitivity can be detected. Similarly, for the forces Fy and Fz and the moments Mx, My, and Mz, there is no other-axis sensitivity and only the main-axis sensitivity can be detected. In other words, a force sensor 10 can be obtained that can suppress the occurrence of other-axis sensitivity.

[0220] Note that cross-axis sensitivity may occur in some cases. For example, when a force Fz acts on the first strain body 40A in the positive direction of the Z axis, the amount of change in the capacitance value of the first capacitance element C1 may differ from the amount of change in the capacitance value of the second capacitance element C2. In this case, cross-axis sensitivity may occur with respect to the force Fz. Furthermore, when the force Fz, moments Mx, and My act on the force receiving body 20, the first strain body 40A is displaced in the Z axis direction. Therefore, the amount of change in the capacitance value may differ in the row for Fz, the row for Mx, and the row for My in the table shown in FIG. 19 even if the same sign is assigned. In this case, cross-axis sensitivity may occur with respect to the force Fz, the moment Mx, and the moment Mz. Similarly, cross-axis sensitivity may occur with respect to the forces Fx, Fy, and the moment Mz. For example, when moment Mx acts on force receiving body 20, as shown in Figure 19, the capacitance values ​​of the third capacitance element C3, the fourth capacitance element C4, the seventh capacitance element C7, and the eighth capacitance element C8 do not change, so the numerical value "0" is entered, but the capacitance value may change and other-axis sensitivity may occur. The same is true for moments My and Mz. Furthermore, for capacitance elements with the numerical value "0" entered in the rows for forces Fx and Fy, the capacitance value may change and other-axis sensitivity may occur.

[0221] However, even if cross-axis sensitivity occurs, a correction calculation can be performed by finding the inverse matrix of the cross-axis sensitivity matrix (a 6-row, 6-column matrix corresponding to the table shown in FIG. 20, also called a characteristic matrix) and multiplying this inverse matrix by the output (characteristic matrix) of the force sensor. As a result, the cross-axis sensitivity can be reduced, and the occurrence of cross-axis sensitivity can be suppressed.

[0222] As described above, according to this embodiment, force receiver 20 includes force receiver main body portion 26 and force receiver thin portion 27, which is thinner than force receiver main body portion 26. Force receiver thin portion 27 is connected to force receiver side end portion 43 of strain generators 40A-40D. This allows force receiver thin portion 27 to elastically deform when subjected to a force in the Z-axis direction, and when a force in the Z-axis direction acts on force receiver 20, force receiver 20 can be displaced in the Z-axis direction. This displaces displacement beams 42 of strain generators 40A-40D, changing the capacitance values ​​of capacitance elements C1-C8. As a result, six-axis components of force or moment can be detected.

[0223] Furthermore, according to this embodiment, the support 30 includes a support main body portion 36 and a support thin portion 37 that is thinner than the support main body portion 36, and the support thin portion 37 is connected to the support side end portion 44 of the strain generating bodies 40A to 40D. This allows the support thin portion 37 to elastically deform when subjected to a force in the Z-axis direction, and when a force in the Z-axis direction acts on the force receiving body 20, the force receiving body 20 can be displaced in the Z-axis direction. This allows the displacement beams 42 of the strain generating bodies 40A to 40D to be displaced, changing the capacitance values ​​of the capacitance elements C1 to C8. As a result, six-axis components of a force or moment can be detected.

[0224] In the above-described embodiment, an example has been described in which the planar shape of force receiver thin portion 27 is circular. However, this is not limited to this. For example, the planar shape of force receiver thin portion 27 may be a circular ring shape. In this case, force receiver thin portion 27 may surround force receiver side end portion 43 in a planar view. In a planar view, the inner portion of force receiver thin portion 27 may have the same thickness as force receiver main portion 26, and force receiver side end portion 43 may be connected to force receiver thin portion 27 via this inner portion. Even in this case, the above-described through hole may be formed in force receiver thin portion 27. The planar shape of force receiver thin portion 27 may be formed in a rectangular ring shape. In this case, the cross-sectional shape of elastically deformable body 41 along the XY plane may also be rectangular.

[0225] In the above-described embodiment, the planar shape of the support thin portion 37 is circular. However, this is not limiting. For example, the planar shape of the support thin portion 37 may be a circular ring shape. In this case, the support thin portion 37 may surround the support side end portion 44 in a planar view. In a planar view, the inner portion of the support thin portion 37 may have the same thickness as the support main body portion 36, and the support side end portion 44 may be connected to the support thin portion 37 via this inner portion. Even in this case, the above-described through hole may be formed in the support thin portion 37. The planar shape of the support thin portion 37 may be formed in a rectangular ring shape. In this case, the cross-sectional shape of the elastically deformable body 41 along the XY plane may also be rectangular.

[0226] The present invention is not limited to the above-described embodiments and modifications, and can be embodied by modifying the components within the scope of the gist of the present invention in the implementation stage. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above-described embodiments and modifications. Some components may be omitted from all the components shown in the embodiments and modifications. Furthermore, components from different embodiments and modifications may be appropriately combined. [Explanation of symbols]

[0227] 1. Robot 10 Force sensor 20 Receptive body 21 1st force receiving body opening 22 2nd force receiving body opening 26 Force receiving body main body 27 Thin section of force receiving body 30 Support 31 First support opening 32 Second support opening 36 Support body 37 Support thin part 40 Strain body 40A 1st strain body 40B 2nd strain body 40C third strain body 40D 4th strain body 41 Elastically deformable body 42 Displacement beam 43 Force receiving body side end 44 Support side end 60 Detector element 70 Detection circuit Ed1~Ed8, Ed21, Ed22, Ed31, Ed32, Ed61, Ed62, Ed71, Ed72 Displacement electrode substrate Ef1~Ef8, Ef21, Ef22, Ef31, Ef32, Ef61, Ef62, Ef71, Ef72 Fixed electrode substrate

Claims

1. a force receiving body that receives the force or moment to be detected; a support body disposed on one side of the force receiving body in the first direction and supporting the force receiving body; a strain generating body connecting the force receiving body and the support body; a detection element for detecting the displacement of the strain generating body; a detection circuit that outputs an electrical signal indicative of the force or moment acting on the force receiving body based on the detection result of the detection element; the strain generating body includes a deformation body extending in the first direction from a force receiving body side end connected to the force receiving body to a support body side end connected to the support body, and a displacement body protruding from the deformation body in a second direction perpendicular to the first direction, the detection element includes a fixed electrode substrate provided on the support body and a displacement electrode substrate provided on the displacement body and facing the fixed electrode substrate, a direction perpendicular to the first direction and the second direction is a third direction; A force sensor, wherein the dimension of the deformable body in the third direction is greater than the dimension of the deformable body in the second direction.

2. the strain element includes two displacement elements protruding in the second direction on both sides of the deformation element, the detection element includes two of the fixed electrode substrates and two of the displacement electrode substrates facing the corresponding fixed electrode substrates; The force sensor according to claim 1 , wherein the displacement electrode substrate is provided on each of the displacement bodies.

3. the force receiving body and the support body are connected by four of the 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 the XYZ three-dimensional coordinate system, When viewed in the Z-axis direction, the first flexure body is disposed on the Y-axis direction negative side with respect to the center of the force receiving body, the second flexure body is disposed on the X-axis direction positive side with respect to the center of the force receiving body, the third flexure body is disposed on the Y-axis direction positive side with respect to the center of the force receiving body, and the fourth flexure body is disposed on the X-axis direction negative side with respect to the center of the force receiving body, the second direction of the first flexure body and the third flexure body is defined as an X-axis direction, 3. The force sensor according to claim 1, wherein the second direction of the second flexure element and the fourth flexure element is a Y-axis direction.

4. 3. The force sensor according to claim 1, wherein the displacement body protrudes from the deformation body at a midpoint between the force receiving body side end and the support body side end.

5. A force receiving body that receives the force or moment to be detected; a support body disposed on one side of the force receiving body in the first direction and supporting the force receiving body; a strain generating body connecting the force receiving body and the support body; a detection element for detecting the displacement of the strain generating body; a detection circuit that outputs an electrical signal indicative of the force or moment acting on the force receiving body based on the detection result of the detection element; the strain generating body includes a deformation body extending in the first direction from a force receiving body side end connected to the force receiving body to a support body side end connected to the support body, and a displacement body protruding from the deformation body in a second direction perpendicular to the first direction, the detection element includes a fixed electrode substrate provided on the support body and a displacement electrode substrate provided on the displacement body and facing the fixed electrode substrate, The force sensor, wherein the force receiving body includes a force receiving body main body portion and a force receiving body thin-walled portion that is thinner than the force receiving body main body portion and is connected to the force receiving body side end of the strain generating body.

6. A force sensor as described in Claim 5, wherein the support includes a support main body portion and a support thin-wall portion that is thinner than the support main body portion and is connected to the support side end of the strain-generating body.

7. A force receiving body that receives the force or moment to be detected; a support body disposed on one side of the force receiving body in the first direction and supporting the force receiving body; a strain generating body connecting the force receiving body and the support body; a detection element for detecting the displacement of the strain generating body; a detection circuit that outputs an electrical signal indicative of the force or moment acting on the force receiving body based on the detection result of the detection element; the strain generating body includes a deformation body extending in the first direction from a force receiving body side end connected to the force receiving body to a support body side end connected to the support body, and a displacement body protruding from the deformation body in a second direction perpendicular to the first direction, the detection element includes a fixed electrode substrate provided on the support body and a displacement electrode substrate provided on the displacement body and facing the fixed electrode substrate, The force sensor, wherein the support includes a support body portion and a support thin-wall portion that is thinner than the support body portion and is connected to the support side end portion of the strain generating body.

8. The force receiving body and the support body are connected by four of the strain generating 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 the XYZ three-dimensional coordinate system, When viewed in the Z-axis direction, the first flexure body is disposed on the Y-axis direction negative side with respect to the center of the force receiving body, the second flexure body is disposed on the X-axis direction positive side with respect to the center of the force receiving body, the third flexure body is disposed on the Y-axis direction positive side with respect to the center of the force receiving body, and the fourth flexure body is disposed on the X-axis direction negative side with respect to the center of the force receiving body, the second direction of the first flexure body and the third flexure body is defined as an X-axis direction, 8. The force sensor according to claim 5, wherein the second direction of the second flexure element and the fourth flexure element is a Y-axis direction.

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