JP5568768B2 - Force detection device - Google Patents

Description

  The present invention relates to a force detection device, and more particularly, to a force detection device suitable for detecting force and moment independently.

  Various types of force detection devices are used to control the operation of robots and industrial machines. Also, a small force detection device is incorporated as a man-machine interface of an input device of an electronic device. In order to reduce the size and reduce the cost, the force detection device used for such an application has a simple structure as much as possible and can independently detect forces related to each coordinate axis in a three-dimensional space. Is required.

  Currently, the multi-axis force detection devices that are generally used are of a type that detects a specific direction component of a force acting on a three-dimensional structure as a displacement generated in a specific portion, and occurs in a specific portion. It is classified as a type to detect as mechanical strain. A typical example of the former displacement detection type is a capacitive element type force detection device, in which a capacitive element is constituted by a pair of electrodes, and the displacement generated in one electrode by the applied force is detected by the capacitive element. The detection is based on the capacitance value. For example, Patent Document 1 below discloses this capacitance-type force detection device. On the other hand, a representative of the latter strain detection type is a strain gauge type force detection device that detects mechanical strain caused by an applied force as a change in electrical resistance such as gauge resistance. For example, Patent Literature 2 below discloses this strain gauge type force detection device.

JP-A-5-215627 Japanese Patent Application Laid-Open No. 61-292029

  In general, the detection target of the force detection device includes a force component directed in a predetermined coordinate axis direction and a moment component around the predetermined coordinate axis. When the XYZ three-dimensional coordinate system is defined in the three-dimensional space, the detection target is six components including force components Fx, Fy, Fz in the respective coordinate axis directions and moment components Mx, My, Mz around the respective coordinate axes. . However, in order to detect each of these components independently, conventionally, a force detection device having a fairly complicated three-dimensional structure, whether of a displacement detection type or a strain detection type, is used. It was necessary to use it.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a force detection device capable of distinguishing and detecting force and moment with a simple structure as much as possible.

(1) A first aspect of the present invention is a force detection device that detects a moment Mz about the Z axis in an XYZ three-dimensional coordinate system.
A force receiving body made of a plate-like member arranged at the origin position of the coordinate system to receive the force to be detected and extending along the XY plane;
A support body composed of a plate-like member disposed below the force receiving body and extending along a plane parallel to the XY plane;
By a structure in which the upper end is connected to the force receiving body via a flexible connecting member, the lower end is connected to the support via a flexible connecting member, and the Z-axis direction is the longitudinal direction. A configured first force transmission body;
By a structure in which the upper end is connected to the force receiving body via a flexible connecting member, the lower end is connected to the support via a flexible connecting member, and the Z-axis direction is the longitudinal direction. A second force transmission body configured;
A first sensor having a function of detecting the inclination of the first force transmission body with respect to the Y-axis direction with respect to the support;
A second sensor having a function of detecting the inclination of the second force transmission body with respect to the Y-axis direction with respect to the support;
In consideration of the detection results of the first and second sensors, a detection processing unit that performs a process of detecting a moment acting on the force receiving body;
Provided,
The first and second force transmission bodies are constituted by columnar members, the connection member is constituted by a diaphragm, and the lower surfaces of the first and second force transmission bodies are arranged at the center of the diaphragm whose periphery is fixed to the support body. The upper surfaces of the first and second force transmission bodies are joined to the center of the diaphragm whose periphery is fixed to the force receiving body,
The first and second sensors have a capacitive element that includes a fixed electrode fixed to the upper surface of the support and a displacement electrode fixed to the displacement surface of the diaphragm joined to the lower surface of the force transmission body. And detecting based on the capacitance value of this capacitive element,
The first force transmission body is disposed at a position where the longitudinal direction of the first force transmission body intersects with the positive portion of the X axis, and the second force transmission body is disposed at a position where the longitudinal direction of the second force transmission body intersects with the negative portion of the X axis.
The force that the detection processing unit has acted on the force receiving member based on the difference between the inclination in the Y-axis direction detected by the first sensor and the inclination in the Y-axis direction detected by the second sensor The process for detecting the moment Mz around the Z axis is performed.

(2) A second aspect of the present invention is a force detection device that detects a moment My around the Y axis in an XYZ three-dimensional coordinate system.
A force receiving body made of a plate-like member arranged at the origin position of the coordinate system to receive the force to be detected and extending along the XY plane;
A support body composed of a plate-like member disposed below the force receiving body and extending along a plane parallel to the XY plane;
By a structure in which the upper end is connected to the force receiving body via a flexible connecting member, the lower end is connected to the support via a flexible connecting member, and the Z-axis direction is the longitudinal direction. A configured first force transmission body;
By a structure in which the upper end is connected to the force receiving body via a flexible connecting member, the lower end is connected to the support via a flexible connecting member, and the Z-axis direction is the longitudinal direction. A second force transmission body configured;
A first sensor having a function of detecting a force in the Z-axis direction applied from the first force transmission body to the support;
A second sensor having a function of detecting a force in the Z-axis direction applied from the second force transmission body to the support;
In consideration of the detection results of the first and second sensors, a detection processing unit that performs a process of detecting a moment acting on the force receiving body;
Provided,
The first and second force transmission bodies are constituted by columnar members, the connection member is constituted by a diaphragm, and the lower surfaces of the first and second force transmission bodies are arranged at the center of the diaphragm whose periphery is fixed to the support body. The upper surfaces of the first and second force transmission bodies are joined to the center of the diaphragm whose periphery is fixed to the force receiving body,
The first and second sensors have a capacitive element that includes a fixed electrode fixed to the upper surface of the support and a displacement electrode fixed to the displacement surface of the diaphragm joined to the lower surface of the force transmission body. And detecting based on the capacitance value of this capacitive element,
The first force transmission body is disposed at a position where the longitudinal direction of the first force transmission body intersects with the positive portion of the X axis, and the second force transmission body is disposed at a position where the longitudinal direction of the second force transmission body intersects with the negative portion of the X axis.
Y of the force acting on the force receiving body based on the difference between the force in the Z-axis direction detected by the first sensor and the force in the Z-axis direction detected by the second sensor. A process for detecting the moment My around the axis is performed.

(3) According to a third aspect of the present invention, there is provided a force detection device for detecting forces Fx and Fz in the coordinate axis directions and moments Mx and My around the coordinate axes in an XYZ three-dimensional coordinate system.
A force receiving body made of a plate-like member arranged at the origin position of the coordinate system to receive the force to be detected and extending along the XY plane;
A support body composed of a plate-like member disposed below the force receiving body and extending along a plane parallel to the XY plane;
By a structure in which the upper end is connected to the force receiving body via a flexible connecting member, the lower end is connected to the support via a flexible connecting member, and the Z-axis direction is the longitudinal direction. A configured first force transmission body;
By a structure in which the upper end is connected to the force receiving body via a flexible connecting member, the lower end is connected to the support via a flexible connecting member, and the Z-axis direction is the longitudinal direction. A second force transmission body configured;
A function of detecting an inclination of the first force transmission body with respect to the X-axis direction, a function of detecting an inclination of the first force transmission body with respect to the Y-axis direction, and a first force transmission body; A first sensor having a function of detecting a force in the Z-axis direction applied to the support from
A function of detecting the inclination of the second force transmission body in the X-axis direction with respect to the support, a function of detecting the inclination of the second force transmission body in the Y-axis direction, and a second force transmission body A second sensor having a function of detecting a force in the Z-axis direction applied to the support from
In consideration of the detection results of the first and second sensors, a detection processing unit that performs a process of detecting a force and a moment acting on the force receiving body;
Provided,
The first and second force transmission bodies are constituted by columnar members, the connection member is constituted by a diaphragm, and the lower surfaces of the first and second force transmission bodies are arranged at the center of the diaphragm whose periphery is fixed to the support body. The upper surfaces of the first and second force transmission bodies are joined to the center of the diaphragm whose periphery is fixed to the force receiving body,
The first and second sensors have a capacitive element that includes a fixed electrode fixed to the upper surface of the support and a displacement electrode fixed to the displacement surface of the diaphragm joined to the lower surface of the force transmission body. And detecting based on the capacitance value of this capacitive element,
The first force transmission body is disposed at a position where the longitudinal direction of the first force transmission body intersects with the positive portion of the X axis, and the second force transmission body is disposed at a position where the longitudinal direction of the second force transmission body intersects with the negative portion of the X axis.
The detection processing unit
The X-axis direction component of the force acting on the force receiving body based on the sum of the inclination degree in the X-axis direction detected by the first sensor and the inclination degree in the X-axis direction detected by the second sensor Perform processing to detect Fx,
Based on the sum of the force related to the Z-axis direction detected by the first sensor and the force related to the Z-axis direction detected by the second sensor, the Z-axis direction component Fz of the force acting on the force receiving body is calculated. Process to detect,
A moment Mx about the X-axis acting on the force receiving member based on the sum of the inclination in the Y-axis direction detected by the first sensor and the inclination in the Y-axis direction detected by the second sensor Process to detect,
Based on the difference between the force in the Z-axis direction detected by the first sensor and the force in the Z-axis direction detected by the second sensor, the moment My around the Y-axis of the force acting on the force receiving body Is performed.

(4) According to a fourth aspect of the present invention, in the force detection device according to the third aspect described above,
The force that the detection processing unit has acted on the force receiving member based on the difference between the inclination in the Y-axis direction detected by the first sensor and the inclination in the Y-axis direction detected by the second sensor The process of detecting the moment Mz about the Z axis is further performed.

(5) According to a fifth aspect of the present invention, in the force detection device according to the first to fourth aspects described above,
By using a flexible and conductive diaphragm as a connecting member on the lower surface side of the force transmission body, the lower surface of the force transmission body is joined to the center of the diaphragm, and the periphery of the diaphragm is fixed to the support body, thereby transmitting force. The body is connected to the support, and the diaphragm itself is used as the displacement electrode.

(6) A sixth aspect of the present invention is the force detection device according to the fifth aspect described above,
When defining an xy two-dimensional coordinate system with the origin at the intersection of the extension line of the axis of the force transmission body made of a columnar member and the upper surface of the support,
The first fixed electrode and the second fixed electrode are disposed on the positive part and the negative part of the x-axis on the upper surface of the support, respectively, and the first fixed electrode and the negative part of the y-axis on the upper surface of the support are respectively arranged on the positive and negative parts. 3 fixed electrodes and a fourth fixed electrode,
The displacement electrode made of a diaphragm and the first to fourth fixed electrodes constitute first to fourth capacitive elements. The capacitance value of the first capacitive element and the capacitance value of the second capacitive element. Based on the difference between the electrostatic capacity value of the third capacitive element and the electrostatic capacity value of the fourth capacitive element. The inclination degree of the transmission body in the y-axis direction is detected, and the detection processing unit performs a process of detecting force or moment using these detection results.

(7) According to a seventh aspect of the present invention, in the force detection device according to the sixth aspect described above,
A fifth fixed electrode is further arranged in the vicinity of the origin on the upper surface of the support, and a fifth capacitive element is constituted by the displacement electrode made of a diaphragm and the fifth fixed electrode. Based on the capacitance value, the force applied from the force transmission body to the support is detected, and the detection processing unit uses this detection result to perform processing to detect force or moment. is there.

(8) According to an eighth aspect of the present invention, in the force detection device according to the fifth to seventh aspects described above,
There is further provided an auxiliary substrate having an opening for inserting the force transmission body and fixed to the support body so as to be disposed above the diaphragm used as a connection member on the lower surface side of the force transmission body ,
The sensor is provided with an auxiliary capacitance element composed of a fixed electrode fixed to the lower surface of the auxiliary substrate and a displacement electrode made of the diaphragm itself, and the detection processing unit uses the capacitance value of the auxiliary capacitance element. Thus, detection of force or moment is performed.

(9) A ninth aspect of the present invention is the force detection device according to the eighth aspect described above,
A part or all of the fixed electrode fixed to the lower surface of the auxiliary substrate forms a mirror image relationship with part or all of the fixed electrode fixed to the upper surface of the support.

(10) According to a tenth aspect of the present invention, in the force detection device according to the first to ninth aspects described above,
The detection processing unit is configured by wiring that electrically connects a plurality of capacitive elements.

(11) An eleventh aspect of the present invention is the force detection device according to the first to tenth aspects described above,
The connecting member for connecting the force receiving body and the force transmitting body is constituted by a thin portion of a plate-like power receiving body.

(12) A twelfth aspect of the present invention is the force detection device according to the first to tenth aspects described above,
An auxiliary sensor for detecting the force applied from each force transmitting body toward the power receiving body is further provided,
The detection processing unit performs processing for detecting the force or moment acting on the force receiving body in consideration of the detection result of the auxiliary sensor.

(13) A thirteenth aspect of the present invention is the force detection apparatus according to the twelfth aspect described above,
The sensor that detects the force applied from the force transmission body toward the support body and the auxiliary sensor that detects the force applied from the force transmission body toward the power receiving body have a mirror image structure,
The detection processing unit executes processing in consideration of this mirror image relationship.

(14) According to a fourteenth aspect of the present invention, in the force detection device according to the first to thirteenth aspects described above,
A limiting member is provided for limiting the displacement of the force receiving body with respect to the support within a predetermined range.

  According to the force detection device of the present invention, it is possible to distinguish and detect force and moment with a structure as simple as possible.

1 is a perspective view (partially a block diagram) showing a basic configuration of a force detection device according to the present invention. It is a front view which shows the fundamental operation | movement principle of the force detection apparatus shown in FIG. FIG. 2 is a side cross-sectional view (a cross-sectional view cut along an xz plane) showing an example of a multi-axis force sensor suitable for use as the first sensor 21 and the second sensor 22 in the force detection device shown in FIG. 1. FIG. 4 is a top view of the multi-axis force sensor shown in FIG. 3. It is a top view of the support body 40 in the multi-axis force sensor shown in FIG. 3 (a broken line has shown the position of the hook-shaped connection member). FIG. 4 is a side sectional view showing a state when a force + fx in the x-axis positive direction is applied to the multi-axis force sensor shown in FIG. 3. FIG. 4 is a side sectional view showing a state when a force −fx in the negative x-axis direction is applied to the multi-axis force sensor shown in FIG. 3. FIG. 4 is a side sectional view showing a state when a force −fz in the negative z-axis direction is applied to the multi-axis force sensor shown in FIG. 3. It is a sectional side view which shows the state which cut | disconnected the main structure part of the force detection apparatus which concerns on the 1st Embodiment of this invention along XZ plane. FIG. 10 is a top view of the force detection device shown in FIG. 9. FIG. 10 is a cross-sectional view illustrating a state where the force detection device illustrated in FIG. 9 is cut along an XY plane. It is a top view of the support body 300 of the force detection device shown in FIG. 10 is a table showing the principle of detection of each force component by the force detection device shown in FIG. 9, and the capacitance value of each capacitive element when each force component acts on the force receiving body 100 of the force detection device shown in FIG. The mode of change is shown. It is a figure which shows the detection principle of each force component by the force detection apparatus shown in FIG. 9 using numerical formula. It is a sectional side view for demonstrating that a force and a moment can be distinguished and detected with the force detection apparatus shown in FIG. It is a top view of the main structure part of the force detection apparatus which concerns on the 2nd Embodiment of this invention. It is a sectional side view which shows the cross section which cut | disconnected the force detection apparatus shown in FIG. 16 along the cutting line 17-17. It is a top view of the support body 300 of the force detection apparatus shown in FIG. 18 is a table showing the principle of detection of each force component by the force detection device shown in FIG. 17, and the capacitance value of each capacitive element when each force component acts on the force receiving body 100 of the force detection device shown in FIG. The mode of change is shown. It is a figure which shows the detection principle of each force component by the numerical formula by the force detection apparatus shown in FIG. It is a top view of the support body 300 of the force detection apparatus which concerns on the 3rd Embodiment of this invention. FIG. 22 is a table showing the principle of detection of each force component by the force detection device shown in FIG. 21, and shows how the capacitance value of each capacitor element changes when each force component acts on the force receiving body 100. It is a figure which shows the detection principle of each force component by the force detection apparatus shown in FIG. 21 using numerical formula. FIG. 10 is a side sectional view showing the structure of a modified example in which a limiting member is added to the force detection device shown in FIG. 9. FIG. 25 is a side sectional view showing a state in which an excessive force + Fx is applied to the force detection device shown in FIG. 24. FIG. 25 is a side sectional view showing a state in which an excessive force + Fz is applied to the force detection device shown in FIG. 24. FIG. 25 is a side sectional view showing a state where an excessive moment + My is applied to the force detection device shown in FIG. 24. It is a sectional side view of the force detection apparatus which concerns on the modification which added the auxiliary substrate 400. It is a bottom view of the auxiliary substrate 400 used in the modification shown in FIG. It is a top view of the support body 300 used for the modification shown in FIG. It is side sectional drawing of the force detection apparatus which concerns on the modification which added the auxiliary sensor. It is a sectional side view of the force detection apparatus which concerns on the modification which added both the auxiliary | assistant board | substrate and the auxiliary sensor. It is a sectional side view of the force detector which concerns on the modification which comprised the power receiving body, the support body, and the force transmission body with the electroconductive material. It is a top view of the support body 300 in the modification using a dummy force transmission body. It is a top view of the support body 300 of the force detection apparatus which concerns on the 4th Embodiment of this invention. FIG. 36 is a table showing the principle of detection of each force component by the force detection device shown in FIG. 35, and shows the manner in which the capacitance value of each capacitive element changes when each force component acts on the force receiving body 100. FIG. It is a figure which shows the detection principle of each force component by the numerical formula by the force detection apparatus shown in FIG.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

<<< §1. Basic concept >>>
First, the basic concept of the force detection device according to the present invention will be described. As shown in FIG. 1, the basic components of the force detection device according to the present invention include a force receiving body 10, a first force transmission body 11, a second force transmission body 12, a support body 20, a first sensor 21, The second sensor 22 and the detection processing unit 30.

  The force receiving body 10 is a component that receives a force to be detected. Here, for convenience of explanation, an origin O is defined at the center position of the force receiving body 10, and an XYZ three-dimensional coordinate system is defined as illustrated. doing. In the illustrated example, the force receiving body 10 having an arbitrary shape is drawn. However, in a specific example described later, a plate-shaped force receiving body 10 is used. The components of the force acting on the force receiving body 10 are force components Fx, Fy, Fz in each coordinate axis direction and moment components Mx, My, Mz around each coordinate axis in this coordinate system. The force detection device shown in FIG. 1 can detect four components of Fx, Fz, Mx, and My among these six force components, as will be described later.

  In the present application, the term “force” is appropriately used when it means a force in a specific coordinate axis direction and when it means a collective force including a moment component. For example, in FIG. 1, the forces Fx, Fy, and Fz mean force components in the coordinate axis directions that are not moments, but six forces Fx, Fy, Fz, Mx, My, and Mz. In this case, it means a collective force including a force component in each coordinate axis direction and a moment component around each coordinate axis.

  The support body 20 is a component that is disposed below the force receiving body 10 and fulfills the function of supporting the force receiving body 10. In the illustrated example, the plate-like support 20 is depicted, but the support 20 does not necessarily have to have a plate-like form. However, as will be described later, the upper surface parallel to the XY plane in the XYZ three-dimensional coordinate system described above is used to detect the force related to the coordinate axes X, Y, and Z by the first sensor 21 and the second sensor 22. It is preferable to use the support body 20 having the above, and it is preferable to use a plate-like form for practical use. Here, for convenience of explanation, an xy plane is defined on the upper surface of the support 20. The xy plane indicated by lowercase letters is a plane parallel to the XY plane indicated by uppercase letters, and the x axis and the X axis are parallel, and the y axis and the Y axis are parallel.

  The first force transmission body 11 and the second force transmission body 12 are members that connect the force receiving body 10 and the support body 20, and are structures disposed along the Z-axis. Are arranged side by side at a predetermined interval on the x-axis. In the example shown in the figure, these force transmission bodies 11 and 12 are both columnar structures, but in principle they may be formed of structures having arbitrary shapes. However, in practice, it is preferable to use a columnar structure as illustrated in order to realize a simple structure. In practice, it is preferable that the first force transmission body 11 and the second force transmission body 12 have the same material and the same size. This is because the detection sensitivity of the first sensor 21 and the second sensor 22 can be made the same if the material and size of both are made the same. If the materials and sizes of the two are different, it becomes difficult to equalize the sensitivities of both sensors, and it is necessary to devise sensitivity correction.

  The important point here is that the upper ends of the force transmitting bodies 11 and 12 are connected to the force receiving body 10 via flexible connecting members (not shown in the figure). The lower ends of the force transmission bodies 11 and 12 are connected to the support body 20 through flexible connection members (not shown in the drawing). In short, the first force transmission body 11 and the second force transmission body 12 are connected to the force receiving body 10 and the support body 20 with flexibility. Here, flexibility is synonymous with elasticity, and in the state where no force is applied to the force receiving body 10, the force receiving body 10 takes a fixed position with respect to the support 20, but When some force is applied to the force body 10, the flexible connecting member is elastically deformed, and the relative position between the force receiving body 10 and the support body 20 is changed. Of course, when the force acting on the force receiving body 10 disappears, the force receiving body 10 returns to the original fixed position.

  After all, in the case of the example shown in FIG. 1, the upper end portion and the lower end portion of the columnar first force transmission body 11 and the second force transmission body 12 are respectively configured by flexible connection members. (Of course, the whole of the first force transmission body 11 and the second force transmission body 12 may be made of a flexible material). And since this connection member produces a certain amount of elastic deformation, the 1st force transmission body 11 and the 2nd force transmission body 12 can incline with respect to the force receiving body 10 and the support body 20. FIG. Further, this connecting member can be expanded and contracted in the vertical direction (Z-axis direction) in the figure. When the force receiving body 10 is moved in the upward direction (+ Z-axis direction) in the figure, the connecting member is extended and received. The distance between the force body 10 and the support body 20 is widened. Conversely, when the force receiving body 10 is moved in the downward direction (−Z-axis direction) in the figure, the connecting member contracts, and the force receiving body 10 and the support body 20 are separated from each other. The distance will be narrowed. Of course, the degree of such displacement and inclination increases according to the magnitude of the force acting on the force receiving body 10.

  The first sensor 21 is a force sensor that detects the force applied from the first force transmission body 11 toward the support body 20, and the second sensor 22 is the second force transmission body 12 to the support body 20. It is a force sensor which detects the force applied toward. As described above, when a force is applied to the force receiving body 10, this force is transmitted to the support body 20 via the first force transmitting body 11 and the second force transmitting body 12. The first sensor 21 and the second sensor 22 have a function of detecting the force transmitted in this way. More specifically, the first sensor 21 and the second sensor 22 are generated when the force transmission body is inclined as described in detail later. By detecting the force, the function of detecting the inclination of the force transmitting body, and the entire force transmitting body applies a pressing force (downward in the figure-force in the Z-axis direction) or tensile force (in the figure). And a function of detecting a force in the upward + Z-axis direction).

  The detection processing unit 30 is a component that performs processing for detecting the force or moment acting on the force receiving body 10 in consideration of both the detection result of the first sensor 21 and the detection result of the second sensor 22. is there. Actually, detection of force and moment is performed based on the inclination of the force transmission body and the pressing force / pulling force applied to the support. The specific method will be described later.

  Next, the basic operation principle of the force detection device shown in FIG. 1 will be described with reference to the front view of FIG. FIG. 2A shows a state in which no force is applied to the force detection device, and the force receiving body 10 maintains a fixed position with respect to the support body 20. Of course, even in this state, since the weight of the force receiving member 10 and the like is applied to the support 20, the support 20 receives some force from the first force transfer member 11 and the second force transfer member 12. Although the force received in this state is a force in a steady state, even if such a force is detected by the first sensor 21 or the second sensor 22, it is output from the detection processing unit 30. The detected value of the applied force or moment is zero. In other words, the detection processing unit 30, when any change has occurred with reference to the detection results of the sensors 21 and 22 in such a steady state, It has a function to detect as a moment.

  Now, let us consider a case where a force + Fx in the positive direction of the X axis is applied to the force receiving member 10 as shown in FIG. 2 (b). This corresponds to a case where a force that pushes the position of the origin O rightward in the figure is applied. In this case, as shown in the figure, the force receiving body 10 slides in the right direction in the figure, and the first force transmitting body 11 and the second force transmitting body 12 are inclined in the right direction in the figure. It will be. Here, the inclination of the first force transmission body 11 at this time is referred to as θ1, and the inclination of the second force transmission body 12 is referred to as θ2. In addition, the angles θ1 and θ2 indicating the degree of inclination in the direction toward the x-axis in the XZ plane are referred to as “degree of inclination in the X-axis direction”. Similarly, an angle indicating the degree of inclination in the direction toward the y-axis in the YZ plane is referred to as “degree of inclination in the Y-axis direction”. In the case shown in the drawing, the two force transmission bodies 11 and 12 are arranged side by side on the x-axis, so the inclination in the Y-axis direction is zero.

  In addition, if each force transmission body 11 and 12 inclines, since the distance of the power receiving body 10 and the support body 20 will shrink a little, strictly speaking, the power receiving body 10 will be completely translated in the X-axis direction. However, if the inclination is relatively small, the amount of movement in the -Z-axis direction can be ignored. For convenience, it is assumed that the force receiving body 10 has moved only in the X-axis direction.

  On the other hand, let us consider a case where a moment + My around the Y-axis acts on the force receiving member 10 as shown in FIG. In FIG. 2 (c), since the Y axis is a vertical axis toward the back side of the page, in the figure, the moment + My rotates the entire force receiving member 10 in the clockwise direction around the origin O. It corresponds to such a force. In the present application, the rotation direction of the right screw when the right screw is advanced in the positive direction of a predetermined coordinate axis is defined as a positive moment around the coordinate axis. In this case, as shown in the figure, an extension force acts on the first force transmission body 11 and a reduction force acts on the second force transmission body 12. As a result, a tensile force (force in the + Z-axis direction: here, referred to as force + fz) acts on the support body 20 from the first force transmission body 11, and the second force transmission body 12. Therefore, a pressing force (a force in the −Z-axis direction: here, a force −fz) is applied to the support 20.

  Thus, in the force detection device according to the present invention, when the force Fx in the X-axis direction is applied to the force receiving body 10 and when the moment My around the Y-axis is applied, the two force transmission bodies 11 are used. , 12, the mode of the force transmitted to the support 20 is different. Therefore, both can be distinguished and detected separately.

  That is, when the force Fx in the X-axis direction is applied, the two force transmission bodies 11 and 12 are inclined in the X-axis direction as shown in FIG. Thus, a force corresponding to such an inclination is transmitted to the support 20. Here, the first force transmission body 11 and the second force transmission body 12 and the flexible connection member for connecting the first force transmission body 11 and the support body 20 are made of the same material and the same size, If the force detection device has a structure that is symmetrical with respect to the Z axis in the figure, the inclination θ1 = θ2. Therefore, the sum (θ1 + θ2) of both is a value indicating the force Fx in the X-axis direction. If the inclination θ is handled with a sign (for example, if the inclination in the X-axis positive direction is treated as positive, and the inclination in the X-axis negative direction is treated as negative), the applied force X in the X-axis direction Fx Can be detected including the sign.

  However, in the present invention, as described later, the inclinations of the first force transmission body 11 and the second force transmission body 12 are applied to the support body 20 by the first sensor 21 and the second sensor 22. Will be detected as force. In order to perform such detection, the force applied from each force transmitting body to the support 20 may be detected for each individual portion. For example, in FIG. 2B, when considering the stress generated in the connection portion between the first force transmission body 11 and the support body 20, the right side portion and the left side portion of the bottom portion of the first force transmission body 11 are It can be seen that the direction of the generated stress is different. That is, in the illustrated example, since the first force transmission body 11 is inclined to the right side, a pressing force is generated on the right side portion of the bottom portion of the first force transmission body 11, and the upper surface of the support body 20 is moved downward. While a pressing force is generated, a pulling force is generated in the left portion, and a force that pulls the upper surface of the support 20 upward is generated. Thus, by detecting the difference in stress between the left and right portions of the bottom of the first force transmission body 11, the inclination of the first force transmission body 11 can be obtained. The specific method will be described in detail in §2.

  In the end, in order to detect the force Fx in the X-axis direction by the force detection device according to the present invention, the first sensor 21 has a tilted state in the x-axis direction with respect to the support 20 of the first force transmission body 11. The second sensor 22 may be provided with a function of detecting the inclined state of the second force transmission body 12 in the x-axis direction with respect to the support body 20. The first sensor 21 has a function of detecting the degree of inclination θ1 in the X-axis direction of the first force transmission body 11, and the second sensor 22 is inclined in the X-axis direction of the second force transmission body 12. If it has a function of detecting the degree, the detection processing unit 30 has the inclination θ1 related to the X-axis direction detected by the first sensor 21 and the inclination related to the X-axis direction detected by the second sensor 22. Based on the sum of the degree θ2, the process of detecting the X-axis direction component Fx of the force acting on the force receiving body 10 can be performed.

  On the other hand, when the moment My around the Y-axis acts, as shown in FIG. 2 (c), the pulling force + fz and the pressing force −fz from the two force transmission bodies 11 and 12 to the support body 20 Is transmitted. The force transmitted in this way is different from the force when the force transmission body is inclined. That is, as shown in FIG. 2 (b), when the force transmission body is inclined, the stress generated at the bottom portion differs between the right side portion and the left side portion. However, as shown in FIG. 2C, when the moment My is applied, a tensile force + fz is applied by the entire first force transmission body 11, and a pressing force -fz is applied by the entire second force transmission body 12. Will be.

  Thus, with respect to the action of the force Fx in the X-axis direction, as shown in FIG. 2B, the first force transmission body 11 and the second force transmission body 12 are inclined in the same direction. While an equivalent event occurs, with respect to the action of the moment My around the Y axis, as shown in FIG. 2 (c), with respect to the first force transmission body 11 and the second force transmission body 12, One contradictory event occurs where one applies a pulling force + fz and the other applies a pressing force -fz. Therefore, the applied moment My can be obtained as a difference between the pulling force + fz and the pressing force −fz, that is, (+ fz) − (− fz) = 2fz.

  In short, in order to detect the moment My around the Y-axis by the force detection device according to the present invention, the force applied to the support body 20 from the entire first force transmission body 11 is applied to the first sensor 21. The second sensor 22 may have a function of detecting the force applied to the support body 20 from the entire second force transmission body 12. The first sensor 21 has a function of detecting a force in the Z-axis direction applied to the support body 20 from the entire first force transmission body 11, and the second sensor 22 is a second force transmission body. 12 has the function of detecting the force in the Z-axis direction applied to the support body 20 from the entire body, the detection processing unit 30 can detect the force in the Z-axis direction detected by the first sensor 21, Based on the difference between the force in the Z-axis direction detected by the second sensor 22, processing for detecting the moment My around the Y-axis of the force acting on the force receiving body 10 can be performed.

<<< §2. Force sensor used in the present invention >>>
The force detection device shown in FIG. 1 is provided with a first sensor 21 and a second sensor 22. These sensors are force sensors that detect the force applied to the support body 20 from the first force transmission body 11 and the second force transmission body 12, respectively, but based on the principle described in FIG. In order to detect the force Fx and the moment My, the force generated by the inclination of the force transmission bodies 11 and 12 and the tensile force / pressing force applied by the force transmission bodies 11 and 12 as a whole are detected independently. A function is required.

  The inventor of the present application considers that a capacitive element type multi-axis force sensor is most suitable as a sensor having such a function. FIG. 3 is a side sectional view showing an example of such a capacitive element type multi-axis force sensor. The multi-axis force sensor itself is a known sensor and has been put into practical use in various fields. Here, for the sake of convenience, the basic structure and operation of the multi-axis force sensor will be briefly described.

  As shown in the side sectional view of FIG. 3, this multi-axis force sensor is provided on the upper surface of the plate-like support body 40, the hook-like connection member 50 disposed thereon, the force transmission body 60, and the support body 40. The fixed electrodes E1 to E5 are arranged. As shown in the top view of FIG. 4, the hook-shaped connection member 50 has a shape in which a circular flat-bottomed hook is turned down. Here, for convenience of explanation, an xyz three-dimensional coordinate system is defined in which the origin O is at the center of the upper surface of the support 40 and the x, y, and z axes are defined in the illustrated direction. As shown in the side sectional view of FIG. 3, the hook-shaped connecting member 50 includes a disk-shaped diaphragm 51 corresponding to the flat bottom portion of the hook, a cylindrical side wall portion 52 that supports the periphery thereof, and the side wall. The portion 52 includes a fixing portion 53 for fixing the portion 52 to the upper surface of the support body 40, and a cylindrical force transmission body 60 is connected to the center portion of the upper surface of the diaphragm 51. The origin O is defined at the intersection point between the extension of the axis of the cylindrical force transmission body 60 and the upper surface of the support body 40.

  Here, in this example, the support body 40 and the force transmission body 60 have sufficient rigidity, but the hook-shaped connection member 50 has flexibility (in other words, a property that causes elastic deformation). ing. In this example, the hook-shaped connecting member 50 is made of a thin metal plate, and the support body 40 and the force transmission body 60 are made of an insulating material.

  As shown in the top view of FIG. 5, five fixed electrodes E <b> 1 to E <b> 5 are formed on the top surface of the plate-like support body 40. Here, the fixed electrode E1 is arranged in the positive part of the x axis, the fixed electrode E2 is arranged in the negative part of the x axis, the fixed electrode E3 is arranged in the positive part of the y axis, and the fixed electrode E4 is y They are arranged in the negative part of the axis, and all are electrodes having the same shape and the same size in the shape of a fan that is line-symmetric with respect to each coordinate axis. On the other hand, the fixed electrode E5 is a circular electrode arranged at the position of the origin O. The broken lines in FIG. 5 indicate the position of each part of the hook-shaped connection member 50 fixed on the support body 40. As illustrated, the diaphragm 51 is disposed above the support 40 so as to face all of the fixed electrodes E1 to E5. As described above, if the diaphragm 51 is made of a conductive material such as a metal plate, the diaphragm 51 has flexibility and conductivity, and the diaphragm 51 itself functions as one common displacement electrode. Capacitance elements are formed between the opposing fixed electrodes E1 to E5. Here, five sets of capacitive elements constituted by the fixed electrodes E1 to E5 and the diaphragm 51 functioning as a common displacement electrode are referred to as capacitive elements C1 to C5, respectively.

  Subsequently, when forces having various directional components are applied to the force transmission body 60, how the hook-like connecting member 50 is deformed and what changes are made to the capacitance values of the capacitive elements C1 to C5. Think about what happens.

  First, as shown in FIG. 6, consider a case where a force + fx in the positive x-axis direction is applied to the upper portion of the force transmission body 60. In this case, a force for inclining the force transmission body 60 to the right side acts, and the flexible hook-shaped connection member 50 is deformed as shown in the figure. The left part is inclined so as to move upward. As a result, the distance between both electrodes (the fixed electrode E1 and the diaphragm 51) of the capacitive element C1 is reduced and the capacitance value is increased, but the distance between both electrodes (the fixed electrode E2 and the diaphragm 51) of the capacitive element C2 is increased, The capacitance value decreases. At this time, for the other three sets of capacitive elements C3 to C5, the distance between the electrodes is reduced in the right half, but the distance between the electrodes is increased in the left half, so that the total capacitance value does not change.

  Such deformation is the same when a force + fx ′ in the positive x-axis direction is applied to the lower portion of the force transmission body 60. However, even if the size of + fx is equal to the size of + fx ′, the former causes a larger deformation due to the principle of leverage.

  On the other hand, as shown in FIG. 7, a case where a force −fx in the negative x-axis direction is applied to the upper portion of the force transmission body 60 will be considered. In this case, a force for inclining the force transmission body 60 to the left side acts, and the flexible hook-shaped connection member 50 is deformed as shown in the figure. The right part is inclined so as to move upward. As a result, the capacitance value of the capacitive element C1 decreases and the capacitance value of the capacitive element C2 increases.

  Eventually, the force fx in the x-axis direction applied to the force transmission body 60 can be obtained as a difference between the capacitance value of the first capacitance element C1 and the capacitance value of the second capacitance element C2. . The magnitude of the obtained difference indicates the magnitude of the applied force, and the sign of the obtained difference indicates the direction of the applied force. Based on the same principle, the force fy in the y-axis direction applied to the force transmission body 60 is the difference between the capacitance value of the third capacitance element C3 and the capacitance value of the fourth capacitance element C4. Can be sought.

  By the way, the force fx obtained in this way indicates the inclination of the columnar force transmission body 60 in the x-axis direction, and the force fy indicates the inclination of the columnar force transmission body 60 in the y-axis direction. Don't be. Eventually, the inclination of the force transmission body 60 in the x-axis direction can be obtained as a difference between the capacitance value of the first capacitance element C1 and the capacitance value of the second capacitance element C2, and the force transmission body The inclination of 60 in the y-axis direction can be obtained as a difference between the capacitance value of the third capacitance element C3 and the capacitance value of the fourth capacitance element C4. In other words, based on the difference between the force applied from the first portion at the lower end of the force transmitting body 60 and the force applied from the second portion at the lower end of the force transmitting body 60, the support of the force transmitting body 60 is supported. The inclination with respect to the body 40 can be detected.

  Next, as shown in FIG. 8, consider a case where a force −fz in the negative z-axis direction is applied to the force transmission body 60. In this case, since a downward force in the figure is applied to the entire force transmission body 60, the force transmission body 60 is not inclined and is applied to the bowl-shaped connection member 50 by the entire force transmission body 60. As a result, the flexible hook-shaped connecting member 50 is deformed as shown in the figure, and the interval between all the electrodes of the five capacitive elements C1 to C5 is reduced. The capacitance value increases. On the other hand, when a force + fz for pulling up the force transmission body 60 is applied, the force transmission body 60 as a whole exerts an upward pulling force on the hook-like connection member 50, and 5 sets All electrode intervals of the capacitive elements C1 to C5 are widened, and the capacitance value is reduced.

  Eventually, in an environment where only the force fz in the z-axis direction is acting on the force transmission body 60, if any one of the capacitance values of the first to fifth capacitive elements C1 to C5 is detected, the effect is obtained. The applied force fz can be obtained. However, in an environment where forces fx and fy of other axial components are mixed, for example, the capacitance value of the capacitive element C1 is obtained alone, or the capacitance value of the capacitive element C3 is obtained alone. However, these are not necessarily values indicating the force fz in the z-axis direction. In any environment, in order to detect the force fz in the z-axis direction, the capacitance value of the capacitive element C5 may be used. As described above, when the force fx in the x-axis direction or the force fy in the y-axis direction is applied, the capacitance value of the capacitive element C5 does not change, so the capacitance value of the capacitive element C5 is used. Then, only the force fz in the z-axis direction can be detected independently.

  However, another method may be used to independently detect only the force fz in the z-axis direction. For example, the sum of the capacitance value of the capacitive element C1 and the capacitance value of the capacitive element C2 can be obtained and used as a detected value of the force fz in the z-axis direction. For the action of the force fx in the x-axis direction, the increase / decrease in the capacitance value of the capacitive element C1 and the increase / decrease in the capacitance value of the capacitive element C2 have a complementary relationship. The component of the force fx in the x-axis direction can be canceled, and only the detected value of the force fz in the z-axis direction can be taken out. Similarly, the sum of the capacitance value of the capacitive element C3 and the capacitance value of the capacitive element C4 can be obtained and used as a detected value of the force fz in the z-axis direction. Further, the sum of the capacitance values of the four sets of capacitance elements C1 to C4 and the sum of the capacitance values of the five sets of capacitance elements C1 to C5 are obtained and used as the detection value of the force fz in the z-axis direction. It is also possible to do. Therefore, the fixed electrode E5 (capacitance element C5) is not necessarily provided.

  As described above, when the multi-axis force sensor shown in FIG. 3 is used, the inclination of the force transmission body 60 in the x-axis direction (force fx) and the inclination of the force transmission body 60 in the y-axis direction (force fy) The force (force fz) applied to the support body 40 from the entire force transmission body 60 can be detected. This means that the multi-axis force sensor shown in FIG. 3 can be used as the first sensor 21 and the second sensor 22 in the force detection device shown in FIG. Of course, the sensor used in the force detection device according to the present invention is not limited to the sensor of the type shown in FIG. 3, but the sensor of the type shown in FIG. 3 has a simple structure and is suitable for mass production. Therefore, it is optimal as a sensor used in the force detection device according to the present invention.

<<< §3. First embodiment of the present invention >>>
Subsequently, the main structural portion of the force detection device according to the first embodiment of the present invention will be described with reference to FIGS. 9 to 12, and the operation principle of this device will be described with reference to FIGS. explain.

  FIG. 9 is a side sectional view showing a state in which the main structural portion of the force detection device according to the first embodiment is cut along the XZ plane, and FIG. 10 is a top view thereof. As shown in FIG. 9, the basic components of this force detection device are a force receiving body 100, an intermediate body 200, and a support body 300, all of which are basically plate-like members having a square upper surface. It is in form.

  As shown in FIG. 10, the force receiving body 100 is basically a plate-like member having a square upper surface, but the two cylindrical protrusions 110 and 120 extend downward from the lower surface. . FIG. 11 is a cross-sectional view showing a state where the force receiving body 100 is cut along the XY plane. As shown in the figure, annular grooves G11 and G12 are formed around the base portions of the cylindrical protrusions 110 and 120. By forming the grooves G11 and G12, the plate-shaped force receiving body 100 includes: As shown in FIGS. 9 and 10, thin portions 115 and 125 having flexibility are formed. Eventually, the cylindrical protrusions 110 and 120 are connected to the plate-shaped force receiving body 100 via the thin portions 115 and 125.

  On the other hand, as shown in FIG. 12, the support 300 is a complete plate-like member having a square upper surface, and fixed electrodes E11 to E15 and E21 to E25 are arranged on the upper surface. The intermediate body 200 joined to the upper surface of the support 300 is basically a plate-like member having a square upper surface, but as shown in FIG. 210 and 220 extend upward. Annular grooves G21 and G22 are formed around the bases of the cylindrical protrusions 210 and 220. Further, cylindrical grooves G31 and G32 are formed on the lower surface of the intermediate body 200. Yes. The groove portions G21 and G22 provided on the upper surface of the intermediate body 200 and the groove portions G31 and G32 provided on the lower surface are both circular outlines of the same size with the center axis position of the cylindrical protrusions 210 and 220 as the center. have. As illustrated, a diaphragm 215 exists as a boundary wall between the groove portions G21 and G31, and a diaphragm 225 exists as a boundary wall between the groove portions G22 and G32.

  The lower surfaces of the two columnar protrusions 110 and 120 extending downward from the force receiving body 100 side are joined to the upper surfaces of the two columnar protrusions 210 and 220 extending upward from the intermediate body 200 side. Here, a cylindrical structure formed by joining the cylindrical projection 110 and the cylindrical projection 210 is called a first force transmission body T1, and the cylindrical projection 120 and the cylindrical projection 220 are joined. A cylindrical structure formed by the above is referred to as a second force transmission body T2 (here, for convenience of explanation, the force transmission body arranged in the positive direction of the X axis is the first, negative direction of the X axis) The force transmission body arranged on the second side is the second). Eventually, the upper end of the first force transmission body T1 is connected to the force receiving body 100 with the thin portion 115 having flexibility as a connecting member, and the upper end of the second force transmission body T2 is flexible. Thus, the thin portion 125 having the connection is connected to the force receiving body 100 as a connecting member.

  The lower surface of the first force transmission body T1 is joined to the center of the diaphragm 215 functioning as a connection member, and the periphery of the diaphragm 215 is connected to the support body 300 via the intermediate body 200. The lower surface of the second force transmission body T2 is joined to the center of the diaphragm 225 functioning as a connecting member, and the periphery of the diaphragm 225 is connected to the support body 300 via the intermediate body 200.

  In the illustrated embodiment, the power receiving body 100 is an insulating substrate (for example, a ceramic substrate), the intermediate body 200 is a conductive substrate (for example, a metal substrate such as stainless steel, aluminum, titanium, etc.), and the support 300 is an insulating substrate (for example). For example, a ceramic substrate is used. Of course, the material of each part is not limited to these, For example, you may comprise the power receiving body 100 with metal substrates, such as stainless steel, aluminum, and titanium. The thin portions 115 and 125 and the diaphragms 215 and 225 are portions configured to have flexibility by reducing the thickness compared to other portions of the substrate.

  Since the diaphragms 215 and 225 are made of a conductive material, the diaphragms 215 and 225 have flexibility and conductivity, and themselves function as common displacement electrodes. This is exactly the same as the configuration of the multi-axis force sensor shown in FIG. That is, the fixed electrodes E11 to E15 shown on the right side of FIG. 12 and the fixed electrodes E21 to E25 shown on the left side of FIG. 12 are all equivalent to the fixed electrodes E1 to E5 shown in FIG. The diaphragms 215 and 225 shown in FIG. 9 are equivalent to the diaphragm 51 shown in FIG. Therefore, sensors S1 and S2 having functions equivalent to those of the multiaxial force sensor shown in FIG. 3 are formed around the groove G31 and the groove G32 shown in FIG. Here, the sensor S1 includes an inclination of the first force transmission body T1 in the X-axis direction, an inclination in the Y-axis direction, and a Z-axis applied to the support body 300 from the entire first force transmission body T1. The sensor S2 has a function of detecting the force related to the direction, and the sensor S2 includes the inclination of the second force transmission body T2 in the X-axis direction, the inclination in the Y-axis direction, and the second force transmission body T2. It has a function of detecting the force in the Z-axis direction applied to the support 300 from the whole.

  In this way, it can be understood that the force detection device shown in FIG. 9 is provided with almost the same components as the force detection device shown in FIG. That is, the plate-shaped force receiving body 100 corresponds to the force receiving body 10, the first force transmitting body T1 corresponds to the first force transmitting body 11, and the second force transmitting body T2 is the second force transmitting body. Corresponding to the body 12, the plate-like support 300 corresponds to the support 20, the sensor S <b> 1 corresponds to the first sensor 21, and the sensor S <b> 2 corresponds to the second sensor 22. Therefore, if the detection processing unit 30 is further added to the structure shown in FIG. 9, the force detection device shown in FIG. 1 can be realized.

  If the force detection device shown in FIG. 1 is used, the force Fx (see FIG. 2B) acting on the force receiving body 10 and the moment My (about the Y axis acting on the force receiving body 10). (See FIG. 2 (c)) can be detected. Actually, however, the force Fz in the Z-axis direction, the moment Mx around the X-axis, and the moment Mz around the Z-axis are further detected. As a result, among the six force components shown in the upper part of FIG. 1, five components Fx, Fz, Mx, My, and Mz can be detected independently. Hereinafter, the reason will be described together with the operation of the force detection device shown in FIG.

  Now, 10 sets of capacitive elements constituted by 10 fixed electrodes E11 to E15 and E21 to E25 shown in FIG. 12 and common displacement electrodes (diaphragms 215 and 225) opposed to the fixed electrodes E11 to E15 and E21 to E25 are respectively C11 to C15. , C21 to C25. C11 to C25 shown in parentheses in FIG. 12 indicate individual capacitive elements constituted by the fixed electrodes. Further, the origin O is set at a predetermined position in the force receiving body 100 shown in FIG. 9, and an XYZ three-dimensional coordinate system is defined as shown. Then, with respect to the force receiving body 100, a positive force about the X axis + Fx, a negative force -Fx, a positive Z axis force + Fz, a negative force -Fz, and a positive force around the X axis. Moment + Mx, Moment in the negative direction -Mx, Moment in the positive direction around the Y axis + My, Moment in the negative direction -My, Moment in the positive direction around the Z axis + Mz, Moment in the negative direction -Mz In this case, consider the change in the capacitance value of each of the 10 sets of capacitive elements C11 to C25.

  FIG. 13 is a table showing how the capacitance values of the capacitive elements C11 to C25 change at this time. “0” indicates no change, “+” indicates an increase, and “−” indicates a decrease. . The reason why the capacitance value of each capacitive element changes as shown in this table can be understood by looking at the deformation modes of the multi-axis force sensor shown in FIGS. For example, when a force + Fx in the X axis positive direction acts on the force receiving body 100, the first force transmitting body T1 and the second force transmitting body T2 are both in the right direction (X axis positive direction in FIG. 9). ), The electrode distance between the capacitive elements C11 and C21 is narrowed and the capacitance value is increased, whereas the electrode distance between the capacitive elements C12 and C22 is widened and the capacitance value is decreased. . For other capacitive elements, the electrode spacing is partially expanded and partially decreased, so that the capacitance value does not change in total. The first row (+ Fx row) of the table of FIG. 13 shows such a change in capacitance value for each of the capacitive elements C11 to C25.

  On the contrary, when the force -Fx in the negative X-axis direction is applied, both the first force transmission body T1 and the second force transmission body T2 are inclined in the left direction (X-axis negative direction) in FIG. Therefore, the relationship between the increase and decrease of the capacitance value is reversed, and a change mode as shown in the second row (-Fx row) of the table of FIG. 13 is obtained.

  Further, when a force + Fz in the positive direction of the Z axis acts on the force receiving body 100, the first force transmitting body T1 and the second force transmitting body T2 are both tensile forces with respect to the upper surface of the support body 300. Therefore, the electrode interval of all the capacitive elements C11 to C25 is widened, and the capacitance value is reduced. The third row (+ Fz row) in the table of FIG. 13 shows such a change. On the contrary, when a force −Fz in the negative Z-axis direction is applied to the force receiving body 100, both the first force transmitting body T <b> 1 and the second force transmitting body T <b> 2 are against the upper surface of the support body 300. Since the pressing force is applied, the electrode interval of all the capacitive elements C11 to C25 is narrowed, and the capacitance value is increased. The fourth line (-Fz line) in the table of FIG. 13 shows such a change.

  On the other hand, when a positive moment + Mx around the X-axis acts on the force receiving body 100, in FIG. 9, the first force transmitting body T1 and the second force transmitting body T2 have a paper surface as a boundary. An upward force is applied to a portion behind the paper surface, and a downward force is applied to a portion in front of the paper surface. That is, in the top view shown in FIG. 10, the point P3 moves upward (Z-axis positive direction), and the point P4 moves downward (Z-axis negative direction). As a result, the electrode intervals of the capacitive elements C13 and C23 shown in FIG. 12 are increased and the capacitance value is decreased, but the electrode intervals of the capacitive elements C14 and C24 are reduced and the capacitance value is increased. For other capacitive elements, the electrode spacing is partially expanded and partially decreased, so that the capacitance value does not change in total. The fifth row (+ Mx row) of the table of FIG. 13 shows such a change in capacitance value for each of the capacitive elements C11 to C25. When a negative moment -Mx around the X axis is applied, the increase / decrease relationship is reversed, and the result shown in the sixth row (-Mx row) of the table of FIG. 13 is obtained.

  When a positive moment + My around the Y-axis acts on the force receiving body 100, a downward force is applied to the first force transmitting body T1 in FIG. An upward force is applied to the second force transmission body T2. That is, in the top view shown in FIG. 10, the point P1 moves downward (Z-axis negative direction), and the point P2 moves upward (Z-axis positive direction). As a result, the electrode spacing of the five sets of capacitive elements C11 to C15 constituting the sensor S1 is narrowed and the capacitance value increases, but the electrode spacing of the five sets of capacitive elements C21 to C25 constituting the sensor S2 is In either case, the capacitance value decreases. The seventh row (+ My row) of the table in FIG. 13 shows such a change in capacitance value for each of the capacitive elements C11 to C25. When a negative moment -My around the Y-axis is applied, the increase / decrease relationship is reversed, and the result shown in the eighth row (-My row) of the table of FIG. 13 is obtained.

  Further, when a positive moment + Mz around the Z axis acts on the force receiving body 100, in FIG. 9, a force for inclining in the Y axis positive direction is applied to the first force transmission body T1. However, a force for inclining in the negative Y-axis direction is applied to the second force transmission body T2. As a result, among the capacitive elements constituting each sensor shown in FIG. 12, the electrode spacing of C13 and C24 is narrowed and the capacitance value is increased, but the electrode spacing of C14 and C23 is widened and the capacitance value is decreased. To do. For other capacitive elements, the electrode spacing is partially expanded and partially decreased, so that the capacitance value does not change in total. The ninth row (+ Mz row) of the table of FIG. 13 shows such a change in capacitance value for each capacitive element. When the negative moment -Mz around the Z-axis is applied, the increase / decrease relationship is reversed, and the result shown in the tenth row (-Mz row) of the table of FIG. 13 is obtained.

  Considering that the results shown in the table of FIG. 13 are obtained, as the detection processing unit 30, the capacitance values of the ten capacitive elements C11 to C25 (here, the capacitance values themselves are the same). If a processing device that performs a calculation based on the equation shown in FIG. 14 using a circuit that measures (measured by C11 to C25) and each measured capacitance value, Fx, Fz, It will be understood that five components Mx, My and Mz can be obtained.

  For example, the formula Fx = (C11−C12) + (C21−C22) shown in FIG. 14 is based on the results of the first and second rows (+ Fx and −Fx rows) of the table of FIG. The inclination of the first force transmission body T1 detected by the first sensor 21 with respect to the X-axis direction, and the inclination of the second force transmission body T2 detected by the second sensor 22 with respect to the X-axis direction This means that the X-axis direction component Fx of the force acting on the force receiving body 100 can be detected based on the sum of. This is based on the detection principle shown in FIG.

  The formula Fz = − (C15 + C25) shown in FIG. 14 is based on the results of the third to fourth rows (+ Fz and −Fz rows) of the table of FIG. 13, and is detected by the first sensor. Based on the sum of the force of the first force transmission body T1 in the Z-axis direction and the force of the second force transmission body T2 detected by the second sensor in the Z-axis direction, the force receiving body 100 This means that the Z-axis direction component Fz of the force acting on can be detected. Note that the minus sign is attached to the head because the upper direction of the apparatus is taken in the positive direction of the Z axis.

  Furthermore, the formula Mx = − ((C13−C14) + (C23−C24)) shown in FIG. 14 is based on the results of the fifth to sixth rows (+ Mx and −Mx rows) of the table of FIG. The inclination of the first force transmission body T1 detected by the first sensor 21 with respect to the Y-axis direction and the second force transmission body T2 detected by the second sensor 22 regarding the Y-axis direction. This means that the moment Mx around the X axis of the force acting on the force receiving body 100 can be detected based on the sum of the inclination and the inclination. Again, the minus sign at the beginning is due to the way the moment is taken.

  Further, the equation My = (C11 + C12 + C13 + C14 + C15)-(C21 + C22 + C23 + C24 + C25) shown in FIG. 14 is based on the results of the seventh to eighth rows (+ My and -My rows) of the table of FIG. Based on the difference between the force in the Z-axis direction of the first force transmission body T1 detected by the sensor and the force in the Z-axis direction of the second force transmission body T2 detected by the second sensor. This means that the moment My around the Y axis of the force acting on the force body 100 can be detected. This is based on the detection principle shown in FIG.

  Finally, the formula of Mz = ((C13−C14) − (C23−C24)) shown in FIG. 14 is based on the results of the ninth to tenth rows (+ Mz and −Mz rows) of the table of FIG. The inclination of the first force transmission body T1 detected by the first sensor 21 with respect to the Y-axis direction and the second force transmission body T2 detected by the second sensor 22 regarding the Y-axis direction. This means that the moment Mz around the Z-axis of the force acting on the force receiving member 100 can be detected based on the difference between the inclination and the inclination.

  In the second formula (Fz formula) in FIG. 14, the capacitance value of one capacitive element C15 is the force in the Z-axis direction of the first force transmission body T1 detected by the first sensor. In the fourth equation (My equation) in FIG. 14, similarly, as the force in the Z-axis direction of the first force transmission body T1 detected by the first sensor, (C11 + C12 + C13 + C14 + C15) The sum of the capacitance values of the five capacitive elements is used. This shows that there are a plurality of variations in the method for obtaining the force in the Z-axis direction using the multi-axis force sensor of the type shown in FIG. 3 as described in §2. Therefore, for example, the second equation in FIG. 14 may be Fz = − ((C11 + C12 + C13 + C14 + C15) + (C21 + C22 + C23 + C24 + C25)). Similarly, the fourth equation in FIG. 14 may be My = (C15−C25). Of course, Fz = − ((C11 + C12) + (C21 + C22)), Fz = − ((C11 + C12 + C13 + C14) + (C21 + C22 + C23 + C24)), My = (C13 + C14 + C15) − (C23 + C24 + C25), and some other variations can be used. is there.

  In the first embodiment shown in FIG. 9, the force Fy in the Y-axis direction acting on the force receiving body 100 cannot be detected. This is because the first force transmission body T1 and the second force transmission body T2 are arranged on the XZ plane (although, approximately, the moment Mx around the X axis is set in the Y axis direction). It is possible to substitute the force Fy). In order to detect all six components including the component Fy, it is necessary to use four columnar force transmission bodies as described in the second and third embodiments described later.

  Here, it should be noted that the technical idea according to the present invention is to improve detection accuracy by simply using two sets of conventionally known multi-axis force sensors as shown in FIG. The technology is completely different from the technology. In general, when performing measurement using any measuring instrument, the technique of “improving measurement accuracy by installing multiple identical measuring instruments and taking the average of the respective measurement results” is a conventional method. Have been used in various fields.

  However, the basic concept of the present invention shown in FIG. 2 is not the technical idea of “improvement of detection accuracy using two sensors”, but “accurately determines the force in the predetermined coordinate axis direction and the moment around the predetermined coordinate axis. It is based on the technical idea of “detecting separately”. Here is a little more detailed supplementary explanation about this point.

  First, as shown in FIG. 6, let us consider detecting a positive force + fx in the x-axis direction using a conventionally known multi-axis force sensor. In a general publicly known document disclosing such a multi-axis force sensor, “the capacitance value C1 of the capacitive element C1 (fixed electrode E1 and diaphragm 51) and the capacitive element C2 (fixed) are fixed according to the principle shown in FIG. The explanation is that the X-axis direction component fx of the force acting on the force transmission body 60 can be obtained by obtaining the difference (C1-C2) between the capacitance value C2 of the electrode E2 and the diaphragm 51). Has been made. However, this explanation is not correct in the strict sense. This is because the difference (C1−C2) in the capacitance value is actually not the applied force fx itself but the moment My around the y-axis caused by the applied force fx.

  This can be easily understood by considering what output values can be obtained when two types of forces + fx and + fx ′ are applied to different positions of the force transmission body 60 as shown in FIG. I can do it. In the illustrated example, even if + fx = + fx ′, the output value obtained as the difference in capacitance value (C1−C2) is greater when + fx is added than when + fx ′ is added. Become bigger. This is because a larger moment can be given to this detection system when + fx is added. In short, the sensor shown in FIG. 6 cannot directly detect the force fx in the x-axis direction and the force fy in the y-axis direction, but only detects them as the moment My around the y-axis and the moment Mx around the x-axis, respectively. There is no.

  However, if the position on the force transmission body 60 to which the force fx is applied is always determined to be a fixed position, there is no problem even if the moment My around the y axis is handled as the force fx in the x axis direction. Therefore, even if the force sensor shown in FIG. 6 is used for detection of the force fx in the x-axis direction and the force fy in the y-axis direction, it is practically used for a detection target that does not need to handle force and moment separately. On top of that, no major hindrance will occur.

  However, for applications such as operation control of robots and industrial machines, there is a considerable demand for force detection devices that can detect force and moment clearly. The force detection device according to the present invention can be said to be a device suitable for such an application. For example, if the force detection device shown in FIG. 9 is used as a joint portion between a robot arm and a wrist, the support body 300 may be attached to the arm side and the force receiving body 100 may be attached to the wrist side. Then, it is possible to detect the force and moment applied to the wrist side with respect to the arm.

  Here, let us consider a case where the force detection apparatus according to the present invention shown in FIG. 9 is used to detect the force in the detection form as shown in FIG. The force detection device shown in FIG. 15 has a cylindrical protrusion 150 connected to the upper surface of the force receiving body 100 of the force detection device shown in FIG. Here, as shown in the figure, let us consider a case where two types of forces + Fx and + Fx ′ are applied to a predetermined position of the cylindrical protrusion 150. In this case, the forces + Fx and + Fx ′ are both forces directed in the positive direction of the X-axis, but are acting at different positions of the cylindrical protrusion 150, and therefore moments having different magnitudes with respect to the force receiving body 100. (Moment in the positive direction around the Y axis + My) is generated.

  Assuming that a force + Fx is applied to the position of the cylindrical protrusion 150 in the figure, both the force + Fx in the X-axis direction and the moment + My around the Y-axis are applied to the force receiving member 100. In the force detection device according to the present invention, the force Fx and the moment My can be detected separately and independently as shown in the equation of FIG. Therefore, no matter what position of the cylindrical protrusion 150 the force Fx is applied to, the value of the force Fx detected by this force detector is always equal. Therefore, in the illustrated example, if + Fx = + Fx ′, the force detection value in the X-axis direction by this force detection device is the same. Of course, the detected value of the moment My around the Y axis at this time is different. The position of the coordinate axis of the moment generated due to the force Fx is determined based on the structure and dimensions of each part of the apparatus.

  As described above, the conventional force sensor shown in FIG. 6 can only detect the force in the X-axis direction as a moment around the Y-axis, whereas the force detection device according to the present invention shown in FIG. The direction force Fx and the moment My around the Y axis can be clearly distinguished and detected. This is an important feature of the present invention.

<<< §4. Second embodiment of the present invention >>>
Next, a force detection device according to a second embodiment of the present invention will be described. FIG. 16 is a top view of the main structural portion of the force detection device according to the second embodiment, and FIG. 17 is a cross-sectional view of the force detection device shown in FIG. 16 cut along a cutting line 17-17. It is a sectional side view shown. The cross section of the force detection device shown in FIG. 16 cut along the cutting line 9-9 is the same as that shown in FIG. The difference from the force detection device according to the first embodiment described above is that four columnar force transmission bodies are provided, and other structures and materials are different from those of the force detection device according to the first embodiment. It is exactly the same. That is, the entire apparatus is composed of a plate-shaped force receiving body 100, intermediate body 200, and support body 300 each having a square upper surface.

  As shown in the top view of FIG. 16, the force receiving body 100 is basically a plate-like member having a square top surface, but from the bottom surface, four cylindrical protrusions 110 of the same size. , 120, 130, 140 extend downward. Here, when the cylindrical projections 110, 120, 130, and 140 define an XY two-dimensional coordinate system having an origin at the center position of the force receiving member 100 as shown in the figure, the first, second, and second, respectively. 3, arranged in the fourth quadrant. More specifically, each of the central axes is positioned at the four apexes of “a square that is arranged at a position centered on the origin and is smaller than the contour of the force receiving body 100 and whose vertical and horizontal directions are parallel to the X axis and the Y axis”. Each cylindrical protrusion 110,120,130,140 is arrange | positioned so that a position may come. In addition, annular groove portions G11, G12, G13, and G14 are formed around the base portions of the cylindrical protrusion portions 110, 120, 130, and 140, and the formation of the groove portions G11, G12, G13, and G14 is performed. The plate-shaped force receiving body 100 is formed with thin portions 115, 125, 135, and 145 having flexibility. Eventually, the cylindrical protrusions 110, 120, 130, and 140 are connected to the plate-shaped force receiving body 100 via the thin portions 115, 125, 135, and 145.

  On the other hand, as shown in FIG. 18, the support 300 is a complete plate-like member having a square upper surface, and fixed electrodes E11 to E15, E21 to E25, E31 to E35, E41 to E45 are formed on the upper surface. Is arranged. The intermediate body 200 bonded to the upper surface of the support 300 is basically a plate-like member having a square upper surface, but the four cylindrical protrusions 210, 220, 230, and 240 from the upper surface. Extends upward (see FIGS. 9 and 17). Annular grooves G21, G22, G23, and G24 are formed around the base portions of the four cylindrical protrusions 210, 220, 230, and 240. Further, on the lower surface of the intermediate body 200, Cylindrical grooves G31, G32, G33, and G34 are formed. The groove portions G21, G22, G23, G24 provided on the upper surface of the intermediate body 200 and the groove portions G31, G32, G33, G34 provided on the lower surface are all center axes of the cylindrical protrusion portions 210, 220, 230, 240. It has a circular outline of the same size around the position of. As shown in FIG. 9, a diaphragm 215 exists as a boundary wall between the groove portions G21 and G31, and a diaphragm 225 exists as a boundary wall between the groove portions G22 and G32. Further, as shown in FIG. 17, a diaphragm 235 exists as a boundary wall between the groove portions G23 and G33, and a diaphragm 245 exists as a boundary wall between the groove portions G24 and G34.

  The bottom surfaces of the four cylindrical protrusions 110, 120, 130, 140 extending downward from the force receiving body 100 side are the four cylindrical protrusions 210, 220, 230, 240 extending upward from the intermediate body 200 side. Bonded to the top surface. Here, as shown in FIG. 9, a columnar structure formed by joining the columnar projection 110 and the columnar projection 210 is referred to as a first force transmission body T1, and the columnar projection 120. The cylindrical structure formed by joining the cylindrical projection 220 and the cylindrical projection 220 is called a second force transmission body T2, and as shown in FIG. 17, the cylindrical projection 130 and the cylindrical projection 230 are A columnar structure formed by bonding is called a third force transmission body T3, and a columnar structure formed by bonding the columnar protrusion 140 and the columnar protrusion 240 is a fourth force transmission body T3. It will be called force transmission body T4.

  After all, the first to fourth force transmission bodies T1 to T4 are arranged in the first to fourth quadrants in the XY two-dimensional coordinate system, respectively, and the upper ends thereof are flexible thin portions 115, 125, 135, and 145 are connected to the force receiving body 100 as connecting members, and lower ends thereof are joined to the centers of diaphragms 215, 225, 235, and 245 that function as connecting members. The support body 300 is connected via the intermediate body 200.

  Since each diaphragm 215, 225, 235, 245 is made of a conductive material, it has flexibility and conductivity, and itself functions as a common displacement electrode. Accordingly, in FIG. 18, the fixed electrodes E11 to E15 arranged in the first quadrant and the diaphragm 215 functioning as a common displacement electrode constitute capacitive elements C11 to C15, functioning as the first sensor S1, The fixed electrodes E21 to E25 arranged in the second quadrant and the diaphragm 225 functioning as the common displacement electrode constitute the capacitive elements C21 to C25, function as the second sensor S2, and arranged in the third quadrant. The fixed electrodes E31 to E35 and the diaphragm 235 functioning as a common displacement electrode constitute capacitive elements C31 to C35, which function as the third sensor S3 and are common to the fixed electrodes E41 to E45 arranged in the fourth quadrant. The capacitive elements C41 to C45 are configured by the diaphragm 245 functioning as a displacement electrode. And functions as a fourth sensor S4.

  By using such a force detection device, it is possible to independently detect all six force components Fx, Fy, Fz, Mx, My, and Mz shown in the upper part of FIG.

  FIG. 19 is a table showing how the capacitance values of the capacitive elements C11 to C45 change at this time. “0” indicates no change, “+” indicates an increase, and “−” indicates a decrease. . In this table, only the values of the six force components Fx, Fy, Fz, Mx, My, and Mz are positive, but if they are negative, the increase / decrease relationship is only reversed. The reason why the capacitance value of each capacitive element changes as shown in the table of FIG. 19 is almost the same as that in the first embodiment described in §3, and therefore detailed description is omitted here.

  However, to give a little supplementary explanation, the table of FIG. 19 is provided with a row of Fy that was not listed in the table of FIG. The reason why the Fy rows can be provided is that four force transmission bodies T1 to T4 are used. That is, if four force transmission bodies T1 to T4 are used, there are two pairs of force transmission bodies (T1, T2, and T3, T4) arranged on the same plane parallel to the XZ plane, and YZ There are two pairs (T1, T4 and T2, T3) of force transmission bodies arranged on the same plane parallel to the plane, and the detection of force components based on the principle shown in FIG. This is because not only the X axis but also the Y axis can be performed.

  Further, by using the four force transmission bodies T1 to T4, the moment Mz around the Z axis can also be detected. For example, referring to FIG. 18, when a positive moment + Mz around the Z-axis (which is a counterclockwise moment on the plan view of FIG. 18) is applied to the force receiving member 100, four force transmissions are performed. Let us consider in which direction the bodies T1 to T4 are inclined.

  First, the first force transmission body T1 (located on the fixed electrode E15 in the figure) arranged in the first quadrant is inclined in the upper left direction in FIG. 18, and the capacitive elements C12, C13 The electrode interval is reduced and the capacitance value is increased, and the electrode interval of the capacitive elements C11 and C14 is increased and the capacitance value is reduced. Further, the second force transmission body T2 (located on the fixed electrode E25 in the figure) arranged in the second quadrant is inclined in the lower left direction in FIG. 18, and the capacitive elements C22, C24. The electrode interval is reduced and the capacitance value is increased, and the electrode interval between the capacitive elements C21 and C23 is increased and the capacitance value is decreased. Further, the third force transmission body T3 (arranged on the fixed electrode E35 in the figure) arranged in the third quadrant is inclined in the lower right direction in FIG. 18, and the capacitive elements C31, C31, The electrode interval of C34 is reduced and the capacitance value is increased, and the electrode interval of the capacitive elements C32 and C33 is increased and the capacitance value is decreased. Finally, the fourth force transmission body T4 (disposed on the fixed electrode E45 in the figure) arranged in the fourth quadrant is inclined in the upper right direction in FIG. 18, and the capacitive elements C41, The electrode interval of C43 is reduced and the capacitance value is increased, and the electrode interval of the capacitive elements C42 and C44 is increased and the capacitance value is decreased. Note that the capacitance values of the capacitive elements C15, C25, C35, and C45 do not change in total.

  Eventually, when a positive moment + Mz around the Z-axis acts on the force receiving body 100, an increase / decrease result as shown in the sixth line of FIG. 19 is obtained. Of course, when a negative moment -Mz around the Z-axis acts on the force receiving member 100, a result obtained by reversing the positive / negative relationship with this is obtained.

  Considering that the results shown in the table of FIG. 19 are obtained, as the detection processing unit 30, the capacitance values of the 20 capacitive elements C11 to C45 (here, the capacitance values themselves are the same). If a processing device that performs a calculation based on the equation shown in FIG. 20 using a circuit that measures (measured by C11 to C45) and each measured capacitance value, Fx, Fy, It will be understood that six components Fz, Mx, My, and Mz can be obtained.

  For example, the formula Fx = (C11−C12) + (C21−C22) + (C31−C32) + (C41−C42) shown in FIG. 20 is the first row (+ Fx row) of the table in FIG. Based on the results, the X-axis of the force acting on the force receiving body 100 based on the sum of the inclinations of the force transmitting bodies T1 to T4 in the X-axis direction detected by the first to fourth sensors. This means that the direction component Fx can be detected. This is based on the detection principle shown in FIG.

  Also, the expression Fy = (C13−C14) + (C23−C24) + (C33−C34) + (C43−C44) shown in FIG. 20 is the second row (+ Fy row) of the table of FIG. Based on the results, the Y-axis of the force acting on the force receiving body 100 based on the sum of the inclinations of the force transmitting bodies T1 to T4 in the Y-axis direction detected by the first to fourth sensors. This means that the direction component Fy can be detected. This is based on the detection principle shown in FIG.

  Further, the expression Fz = − (C15 + C25 + C35 + C45) shown in FIG. 20 is based on the result of the third row (+ Fz row) of the table of FIG. 19 and is detected by the first to fourth sensors. This means that the Z-axis direction component Fz of the force acting on the force receiving body 100 can be detected based on the sum of the forces in the Z-axis direction of the force transmitting bodies T1 to T4. The leading minus sign is based on the Z axis direction.

  On the other hand, the equation Mx = − (((C11 + C12 + C13 + C14 + C15) + (C21 + C22 + C23 + C24 + C25)) − ((C31 + C32 + C33 + C34 + C35)) + (C41 + C42 + C43 + C44 + C45)) shown in FIG. The difference between the sum of the forces in the Z-axis direction detected by the first and second sensors and the sum of the forces in the Z-axis direction detected by the third and fourth sensors This means that the moment Mx around the X axis of the force acting on the force receiving body can be detected. This is a detection in a state where the point P3 is moved upward (Z-axis positive direction) and the point P4 is moved downward (Z-axis negative direction) in the top view shown in FIG. 16, and FIG. This is based on the detection principle shown in FIG. The minus sign at the beginning of the formula is due to the direction of the moment.

  Also, the equation My = ((C11 + C12 + C13 + C14 + C15) + (C41 + C42 + C43 + C44 + C45))-((C21 + C22 + C23 + C24 + C25) + (C31 + C32 + C33 + C34 + C35)) shown in FIG. 20 is based on the fifth row of the table in FIG. Based on the difference between the sum of the forces in the Z-axis direction detected by the first and fourth sensors and the sum of the forces in the Z-axis direction detected by the second and third sensors, This means that the moment My around the Y axis of the force acting on the force receiving body can be detected. This is a detection in a state where the point P1 moves downward (Z-axis negative direction) and the point P2 moves upward (Z-axis positive direction) in the top view shown in FIG. 16, and FIG. This is based on the detection principle shown in FIG.

  Finally, Mz = (((C31-C32) + (C41-C42))-((C11-C12) + (C21-C22))) + (((C13-C14) + (C43-) shown in FIG. C44)) − ((C23−C24) + (C33−C34))) is based on the result of the sixth row (+ Mz row) of the table of FIG. The difference between the sum of the inclinations in the X-axis direction detected by the sensors and the sum of the inclinations in the X-axis direction detected by the first and second sensors is obtained as a first difference, and the first and The difference between the sum of the inclinations in the Y-axis direction detected by the fourth sensor and the sum of the inclinations in the Y-axis direction detected by the second and third sensors is obtained as a second difference, and Based on the sum of the first difference and the second difference, Moment Mz about the Z-axis of the applied force is meant that can be detected.

The meaning of this Mz equation is
Mz = (C12 + C13)-(C11 + C14)
+ (C22 + C24)-(C21 + C23)
+ (C31 + C34)-(C32 + C33)
+ (C41 + C43)-(C42 + C44)
If you rewrite it like this, it will be easier to understand. That is, when a positive moment + Mz around the Z-axis is applied, as described above, in FIG. 18, the first force transmission body T1 disposed on the fixed electrode E15 is inclined in the upper left direction in the figure. Of course, (C12 + C13) − (C11 + C14) in the above expression is a term for detecting such an inclination of the first force transmission body T1. Similarly, the second force transmission body T2 disposed on the fixed electrode E25 is inclined in the lower left direction in the figure, but the above expression (C22 + C24) − (C21 + C23) is the second force. This is a term for detecting such an inclination of the transmission body T2. Further, the third force transmission body T3 disposed on the fixed electrode E35 is inclined in the lower right direction in the figure, but the above formula (C31 + C34) − (C32 + C33) is the third force. This is a term for detecting such an inclination of the transmission body T3. Further, the fourth force transmission body T4 disposed on the fixed electrode E45 is inclined in the upper right direction in the figure, but the above formula (C41 + C43) − (C42 + C44) is the fourth force transmission. This is a term for detecting such a tilt of the body T4. Thus, the above equation shows the sum of the detected values of the inclination in the predetermined direction of the four force transmission bodies T1 to T4 when the moment Mz around the Z axis is applied.

  In addition, as described in §3, there are a plurality of variations in the method for obtaining the force in the Z-axis direction of each of the force transmission bodies T1 to T4, and these variations are included in each equation shown in FIG. It is also possible to apply. For example, an expression of Mx = − ((C15 + C25) − (C35 + C45)) or an expression of My = ((C15 + C45) − (C25 + C35)) may be used.

<<< §5. Third embodiment of the present invention >>>
Next, a force detection device according to a third embodiment of the present invention will be described. The force detection device according to the third embodiment is similar to the force detection device according to the second embodiment described above, and uses four columnar force transmission bodies and detection using four sets of sensors S1 to S4. I do. However, the arrangement of the four columnar force transmission bodies is slightly different. Only this difference will be described below.

  FIG. 21 is a top view of the support 300 used in the force detection device according to the third embodiment. Compared with FIG. 18, which is a top view of the support 300 used in the force detection device according to the second embodiment described above, the difference between the two becomes clear. That is, in the second embodiment, as shown in FIG. 18, the fixed electrodes E11 to E15, E21 to E25, E31 to E35, and E41 to E45, which are the constituent elements of the four sets of sensors S1 to S4, The first to fourth quadrants in the system are arranged, and the first to fourth force transmission bodies T1 to T4 are arranged in the first to fourth quadrants in the XY two-dimensional coordinate system, respectively.

  On the other hand, in the force detection device according to the third embodiment shown in FIG. 21, fixed electrodes E11 to E15, E21 to E25, E31 to E35, E41 to E45, which are constituent elements of the four sets of sensors S1 to S4. Are arranged in the positive part of the x-axis, the negative part of the x-axis, the positive part of the y-axis, and the negative part of the y-axis, respectively, and the lengths of the first to fourth force transmission bodies T1 to T4 In the XY two-dimensional coordinate system, the directions are arranged so as to intersect the positive part of the X axis, the negative part of the X axis, the positive part of the Y axis, and the negative part of the Y axis, respectively. Capacitance elements C11 to C15, C21 to C25, C31 to C35, C41 are formed by the fixed electrodes E11 to E15, E21 to E25, E31 to E35, E41 to E45, and conductive diaphragms (common displacement electrodes) located thereabove. The point where -C45 is formed is the same as in the second embodiment described above. However, since the arrangement of the force transmission body and the sensor is different, the detection processing by the detection processing unit 30 is slightly different.

  FIG. 22 is a table showing changes in the capacitance values of the capacitive elements C11 to C45 in the force detection device according to the third embodiment, where “0” indicates no change and “+” indicates an increase. , “−” Indicates a decrease. Also in this table, only the case where the values of the six force components Fx, Fy, Fz, Mx, My, and Mz are positive is shown, but if it is negative, the increase / decrease relationship is only reversed. . When the table shown in FIG. 22 is compared with the table shown in FIG. 19, the change in the capacitance value of each capacitive element when the force components Fx, Fy, Fz in the respective axial directions are applied is completely the same. is there. Therefore, the detection principle regarding the force components Fx, Fy, and Fz in the respective axial directions is the same as in the case of the second embodiment described above.

  However, when the moments Mx, My, and Mz around the respective axes act, the changes in the capacitance values of the capacitive elements are slightly different, and the detection principle of these moments is the same as that of the second embodiment described above. Not the case. This point will be briefly described below.

  First, when the moment Mx around the X axis acts, a tensile force (+ fz) acts on the support 300 from the third force transmission body T3 arranged in the positive part of the Y axis, A pressing force (−fz) acts on the support body 300 from the fourth force transmission body T4 arranged in the negative portion. At this time, a significant force is applied to the support 300 from the first force transmission body T1 disposed in the positive portion of the X axis and the second force transmission body T2 disposed in the negative portion of the X axis. Does not occur. Actually, there is a partial force acting in the Z-axis direction, but the amount is small compared to the force applied from the third and fourth force transmission bodies, so here the capacitance elements C11 to C15 and C21 to C25 The change in capacitance value is assumed to be “0”. As a result, a result as shown in the fourth row (+ Mx row) in FIG. 22 is obtained.

  On the other hand, when the moment My around the Y axis acts, a pressing force (−fz) acts on the support body 300 from the first force transmission body T1 arranged in the positive portion of the X axis, and the X axis A tensile force (+ fz) acts on the support 300 from the second force transmission body T2 disposed in the negative portion of the. At this time, a significant force is applied to the support 300 from the third force transmission body T3 disposed in the positive portion of the Y axis and the fourth force transmission body T4 disposed in the negative portion of the Y axis. Does not occur. As a result, a result as shown in the fifth line (+ My line) in FIG. 22 is obtained.

  Next, referring to FIG. 21, when force + Mz (a counterclockwise moment on the plan view of FIG. 21) is applied to the force receiving body 100 around the Z axis, four forces are applied. Let us consider in which direction the transmission bodies T1 to T4 are inclined.

  First, the first force transmission body T1 (arranged on the fixed electrode E15 in the figure) arranged in the positive part of the X axis is inclined in the upward direction (positive direction of the y axis) in FIG. As a result, the electrode interval of the capacitive element C13 is reduced and the capacitance value is increased, and the electrode interval of the capacitive element C14 is increased and the capacitance value is reduced. In addition, the second force transmission body T2 (located on the fixed electrode E25 in the figure) arranged in the negative portion of the X axis is inclined downward (in the negative direction of the y axis) in FIG. As a result, the electrode interval of the capacitive element C24 is decreased and the capacitance value is increased, and the electrode interval of the capacitive element C23 is increased and the capacitance value is decreased. Furthermore, the third force transmission body T3 (arranged on the fixed electrode E35 in the figure) disposed in the positive portion of the Y axis is inclined in the left direction (the negative direction of the x axis) in FIG. As a result, the electrode interval of the capacitive element C32 is reduced and the capacitance value is increased, and the electrode interval of the capacitive element C31 is increased and the capacitance value is reduced. Finally, the fourth force transmission body T4 (arranged on the fixed electrode E45 in the figure) arranged in the negative portion of the Y axis is in the right direction (positive direction of the x axis) in FIG. As a result, the gap between the electrodes of the capacitive element C41 is reduced and the capacitance value is increased, and the gap between the electrodes of the capacitive element C42 is increased and the capacitance value is decreased. Note that the capacitance values of the other capacitive elements do not change in total.

  Eventually, when a positive moment + Mz around the Z-axis acts on the force receiving body 100, an increase / decrease result as shown in the sixth line of FIG. 22 is obtained. Of course, when a negative moment -Mz around the Z-axis acts on the force receiving member 100, a result obtained by reversing the positive / negative relationship with this is obtained.

  Considering that the results shown in the table of FIG. 22 are obtained, as the detection processing unit 30, the capacitance values of the 20 capacitive elements C11 to C45 (here, the capacitance values themselves are the same). If a processing device that performs a calculation based on the equation shown in FIG. 23 using a circuit that measures (measured by C11 to C45) and each measured capacitance value, Fx, Fy, Six components of Fz, Mx, My, and Mz can be obtained. Here, the equations for Fx, Fy, and Fz shown in FIG. 23 are exactly the same as the equations shown in FIG.

  The formula Mx = (C41 + C42 + C43 + C44 + C45) − (C31 + C32 + C33 + C34 + C35) shown in FIG. 23 is based on the result of the fourth row (+ Mx row) of the table of FIG. 22 and is detected by the fourth sensor. This means that the moment Mx around the X-axis of the force acting on the force receiving body can be detected based on the difference between the force related to the direction and the force related to the Z-axis direction detected by the third sensor.

  Also, the equation My = (C11 + C12 + C13 + C14 + C15)-(C21 + C22 + C23 + C24 + C25) shown in FIG. 23 is based on the result of the fifth row (+ My row) of the table of FIG. 22, and is detected by the first sensor. This means that the moment My around the Y-axis of the force acting on the force receiving body can be detected based on the difference between the force related to the Z-axis direction and the force related to the Z-axis direction detected by the second sensor. .

  Finally, the equation Mz = ((C13−C14) + (C41−C42)) − ((C23−C24) + (C31−C32)) shown in FIG. 23 is expressed in the sixth row of the table of FIG. + Mz row), and the sum of the inclination with respect to the Y-axis direction detected by the first sensor and the inclination with respect to the X-axis direction detected by the fourth sensor, and the second The moment around the Z-axis of the force acting on the force receiving body based on the difference between the inclination in the Y-axis direction detected by the sensor and the sum of the inclination in the X-axis direction detected by the third sensor This means that Mz can be detected.

  In addition, as described in §3, there are a plurality of variations in the method for obtaining the force in the Z-axis direction of each of the force transmission bodies T1 to T4, and these variations are included in each equation shown in FIG. It is also possible to apply.

<<< §6. Modified example with a limiting member >>>
FIG. 24 is a side sectional view showing a structure of a modification in which a limiting member is added to the force detection device according to the first embodiment shown in FIG. As described in §3, the first sensor S1 and the second sensor S2 are incorporated in the force detection device shown in FIG. 9, and these sensors have thin diaphragms 215 and 225. ing. The diaphragms 215 and 225 have a certain degree of flexibility, and when a force within an allowable range is applied from the force transmission bodies T1 and T2, the diaphragms 215 and 225 are deformed in a predetermined manner as described above. is there. However, if an excessive force is applied to the diaphragms 215 and 225, there is a possibility of mechanical damage such as cracks.

  In the modification shown in FIG. 24, the displacement of the force receiving body 100 with respect to the support body 300 is prevented in order to prevent mechanical damage caused by excessive force transmitted to the diaphragms 215 and 225 in this way. This is an example in which a limiting member for limiting within a predetermined range is provided. In this example, as shown in the figure, a control wall 250 rises from the outer peripheral portion of the intermediate body 200, and a control collar 260 is formed on the upper part. The total length of the two force transmission bodies T1, T2 is also set as short as possible. As a result, the displacement of the force receiving body 100 is limited within a predetermined range.

  For example, the downward displacement (−Z axis direction) of the force receiving body 100 is limited to be within the dimension d1 shown in the figure. Even if a large downward force is applied to the force receiving member 100, the bottom surface of the force receiving member 100 becomes the intermediate member 200 when the downward displacement of the force receiving member 100 reaches the dimension d1. The upper surface will be touched and further displacement will be limited.

  Further, the upward displacement (+ Z-axis direction) of the force receiving body 100 is limited to be within the dimension d2 illustrated. Even if a large upward force is applied to the force receiving member 100, the upper surface of the force receiving member 100 becomes the control collar when the upward displacement of the force receiving member 100 reaches the dimension d2. The lower surface of 260 is contacted, and further displacement is limited.

  Further, the displacement of the force receiving body 100 in the lateral direction (± X axis direction and ± Y axis direction) is limited to be within the dimension d3 shown in the figure. Even if a large lateral force is applied to the force receiving body 100, the side surface of the force receiving body 100 becomes the control wall when the lateral displacement of the force receiving body 100 reaches the dimension d3. It will contact the inner surface of 250 and further displacement is limited. Of course, such a restricting member is also applicable to the devices of the second and third embodiments.

  The state in which the displacement is actually limited by the embodiment using such a limiting member is shown in the side sectional views of FIGS. FIG. 25 shows a state when an excessive force + Fx is applied in the positive direction of the X axis. The right side surface of the force receiving body 100 is in contact with the control wall 250 and further displacement is limited. On the other hand, FIG. 26 shows a state when an excessive force + Fz is applied in the positive direction of the Z axis. The outer upper surface of the force receiving body 100 is in contact with the control collar 260, and further displacement is limited. FIG. 27 shows a state when an excessive moment + My is applied in the positive direction around the Y axis. In this case, a downward force -Fz in the figure is applied to the first force transmission body T1, and an upward force + Fz in the figure is applied to the second force transmission body T2, causing displacement as shown in the figure. Again, further displacement is limited. FIGS. 25 to 27 also show changes in the electrode spacing of each capacitive element, so that it can be understood that changes in the capacitance values shown in the tables of FIGS. 19 and 22 occur.

<<< §7. Modified example with auxiliary substrate and auxiliary capacitance element added >>
Subsequently, a modified example using the auxiliary substrate and the auxiliary capacitance element will be described. First, looking at the six formulas shown in FIG. 20 or the six formulas shown in FIG. 23, all of the five formulas excluding the formula for obtaining the force Fz are subtracted together with addition to the capacitance value. Can be seen. For example, the formula for calculating the force Fx can be summarized as follows:
Fx = (C11 + C21 + C31 + C41)
-(C12 + C22 + C32 + C42)
Also, the formula for calculating the force Fy is organized as follows:
Fy = (C13 + C23 + C33 + C43)
-(C14 + C24 + C34 + C44)
It becomes. As a result, among the six force components, the five components excluding the force Fz have the entire capacitance value of the capacitive element group belonging to one group and the entire electrostatic capacitance value of the capacitive element group belonging to another group. The force or the moment is detected based on the difference between the capacitance value.

  However, the force Fz is not subtracted with respect to the capacitance value, as can be seen from the equation of FIG. 20 or FIG. The minus sign at the head of the formula relating to Fz is due to the way of defining the direction of the coordinate axis. When a force + Fz in the positive direction of the Z-axis is applied, the detected value (capacitance value C15 , C25, C35, and C45) decreases from the reference value, and when the Z-axis negative direction force -Fz is applied, the detected value increases from the reference value.

  Thus, among the six force components, force components other than Fz are all obtained as the difference between the two capacitance values, whereas only the force Fz is not the amount obtained as the difference. become. This is because the detection values of the forces Fx, Fy, Mx, My, and Mz are output as 0 in the state where no force to be detected acts, whereas the detection value of the force Fz is not 0. This means that it is output as a predetermined reference value. Of course, if the reference value is measured in advance and the detected value of the force Fz is output as a difference from the reference value, no problem arises in principle.

  However, a method for obtaining a detection value as a difference between the capacitance values of two capacitive element groups existing in the apparatus, and a detection value as a difference between the capacitance value of a single capacitance element group and a predetermined reference value. There are practically important differences from the method of obtaining. In other words, if the former method is adopted, even if there is some variation in the dimensional accuracy of each lot, the difference can be obtained to offset the error factor, whereas the latter method. Then, such a merit cannot be obtained. In addition, dimensional fluctuations due to thermal expansion of each part may occur depending on the temperature conditions of the environment in which this force detection device is used. However, the former method provides an advantage that the influence of such dimensional fluctuations is offset. On the other hand, the latter method cannot provide such a merit.

  In consideration of such points, in practice, it is preferable to take a technique for obtaining a detection value as a difference between the capacitance values of two capacitive element groups existing in the apparatus as much as possible. Therefore, regarding the detection of the force Fz, it is preferable that detection by the difference can be realized in some form. The modification described here realizes this by providing an auxiliary substrate.

  FIG. 28 is a side sectional view showing a configuration of a force detection device according to a modification using the auxiliary substrate. The basic structure of this modification is substantially the same as the structure of the force detection device according to the second embodiment described above, and the top view thereof is equivalent to the top view shown in FIG. FIG. 28 is a side cross-sectional view showing a cross section of the force detection device according to the modification using the auxiliary substrate, taken at a position corresponding to the cutting line 9-9 in FIG. The difference between the modification shown in FIG. 28 and the second embodiment described above is the following two points.

  First, as shown in FIG. 28, the first difference is that an auxiliary substrate 400 is provided on the upper surface of the intermediate body 200, and fixed electrodes E16, E26, E36, E46 (E36, E46 are , Which is not shown in FIG. 28) (the thickness of the intermediate body 200 is also slightly reduced). FIG. 29 is a bottom view of the auxiliary substrate 400, and a cross section of the auxiliary substrate 400 taken along the cutting line 28-28 in the drawing is shown in FIG. The auxiliary substrate 400 has openings H1 to H4 through which the force transmission bodies T1 to T4 are inserted. The diameters of the openings H1 to H4 are set to be slightly larger than the diameters of the force transmission bodies T1 to T4, and do not contact the auxiliary substrate 400 even if the force transmission bodies T1 to T4 are inclined or displaced. It is like that.

  The auxiliary substrate 400 is made of an insulating material and bonded to the upper surface of the intermediate body 200. In other words, the auxiliary substrate 400 is fixed to the support body 300 via the intermediate body 200 so as to be disposed above the diaphragms 215, 225, 235, and 245 and to be parallel to the XY plane. Will be. Around each of the openings H1 to H4, annular fixed electrodes E16, E26, E36, and E46 are formed, respectively.

  The second difference is that, in the second embodiment described above, a total of 20 fixed electrodes as shown in FIG. 18 are formed on the support 300, whereas in the modification shown here, A total of 20 fixed electrodes as shown in FIG. 30 are formed. In any case, fixed electrodes E11 to E15 are arranged in the first quadrant in the xy coordinate system, fixed electrodes E21 to E25 are arranged in the second quadrant, fixed electrodes E31 to E35 are arranged in the third quadrant, and fixed electrodes E41 to E45 are arranged in the fourth quadrant. This is the same, and the function of configuring a total of 20 capacitive elements C11 to C15, C21 to C25, C31 to C35, and C41 to C45 is also the same. The difference between the two is the shape of each electrode, as can be seen by comparing FIG. 18 and FIG.

  Thus, the reason for changing the shape of the fixed electrode formed on the support 300 is that the shape and arrangement of the fixed electrodes E15, E25, E35, and E45 used for detecting the force Fz are changed to the auxiliary substrate shown in FIG. This is because the shape and arrangement of the fixed electrodes E16, E26, E36, and E46 on the 400 side are the same. Since the openings H1 to H4 through which the force transmission bodies T1 to T4 are inserted are formed in the auxiliary substrate 400, the shape and arrangement of the fixed electrodes E16, E26, E36, and E46 must be restricted. In the example shown in FIG. 29, the fixed electrodes E16, E26, E36, and E46 are annular (washer-like) electrodes that surround the vicinity of the outer periphery of the openings H1 to H4. Therefore, the fixed electrode E15 shown in FIG. , E25, E35, E45 are also annular electrodes having the same shape and size. As a result, the shape of the other electrodes E11 to E14, E21 to E24, E31 to E34, and E41 to E44 is slightly changed.

  The side cross section of each of these electrodes is a very fine region in the drawing, and is shown as a black region in FIG. As apparent from FIG. 28, the fixed electrodes E15 and E25 formed on the upper surface of the support 300 and the fixed electrodes E16 and E26 formed on the lower surface of the auxiliary substrate 400 are formed as diaphragms 215 and 225. A mirror image relation is formed with respect to the plane (horizontal plane passing through the center position of the thickness). Although not shown in the figure, the fixed electrodes E35 and E45 formed on the upper surface of the support 300 and the fixed electrodes E36 and E46 formed on the lower surface of the auxiliary substrate 400 are the surfaces on which the diaphragms 235 and 245 are formed. Make a mirror image relationship.

  Here, the four fixed electrodes E16, E26, E36, and E46 formed on the auxiliary substrate 400 side, and the opposing portions of the diaphragms 215, 225, 235, and 245 made of a conductive material, respectively, capacitive elements C16 and C26. , C36, C46 (hereinafter referred to as auxiliary capacitance elements) are formed. After all, in this modified example, a total of 24 fixed electrodes are provided, 20 of which are formed on the upper surface of the support 300 (see FIG. 30), but the remaining 4 are It is formed on the lower surface of the auxiliary substrate 400 (see FIG. 29). As a result, a total of 20 sets of capacitive elements are arranged below the diaphragms 215, 225, 235, and 245, and 4 sets of auxiliary capacitive elements are arranged above the diaphragms 215, 225, 235, and 245.

  The feature of this modification is that a specific force component is obtained by using the capacitance value of the auxiliary capacitance element constituted by the fixed electrode fixed to the lower surface of the auxiliary substrate 400 and the displacement electrode made of the diaphragm itself. The point is that detection is performed. More specifically, the auxiliary capacitive elements C16, C26, C36, and C46 are used for detecting the force Fz, similarly to the capacitive elements C15, C25, C35, and C45. However, the increase / decrease in the capacitance values of the auxiliary capacitance elements C16, C26, C36, C46 is completely opposite to the increase / decrease in the capacitance values of the capacitance elements C15, C25, C35, C45. This can be easily understood from the side sectional view of FIG. For example, when a force + Fz in the positive direction of the Z axis is applied to the force receiving body 100, the force transmission bodies T1 to T4 are displaced upward in the figure, and the diaphragms 215 to 245 are also displaced upward. Therefore, the electrode intervals of the capacitive elements C15, C25, C35, and C45 formed below the diaphragms 215 to 245 are all widened, and the capacitance value is decreased, whereas the capacitance elements C15, C25, C35, and C45 are formed above the diaphragms 215 to 245. The electrode intervals of the auxiliary capacitance elements C16, C26, C36, and C46 thus made narrow, and the capacitance value increases. The phenomenon when the force -Fz in the negative Z-axis direction is applied to the force receiving member 100 is completely opposite to this.

Eventually, in the force detection device according to this embodiment, instead of the equation of force Fz shown in FIG.
Fz = (C16 + C26 + C36 + C46)
-(C15 + C25 + C35 + C45)
The following formula can be used. This is detection based on the difference between the entire capacitance value of the capacitive element group belonging to one group and the overall capacitance value of the capacitive element group belonging to another group, as described above. In addition, it is possible to obtain an advantage of offsetting errors based on dimensional accuracy for each lot and errors due to temperature fluctuations.

  The fixed electrodes E15, E25, E35, and E45 formed on the upper surface of the support 300 and the fixed electrodes E16, E26, E36, and E46 formed on the lower surface of the auxiliary substrate 400 have a mirror image relationship with respect to the diaphragm forming surface. This is because the force Fz can be detected by a simple arithmetic expression as described above. For example, if the fixed electrodes E15 and E16 have a mirror image relationship, the capacitive element C15 and the auxiliary capacitive element C16 are physically identical in shape and size, and the capacitance value due to the displacement of the diaphragm 215 is reduced. Increase and decrease are complementary. Therefore, it is possible to use a simple arithmetic expression that does not include a coefficient term in each capacitance value, as in the above-described expression. In other words, if the coefficient term is included in the arithmetic expression, the fixed electrode formed on the support 300 side and the fixed electrode formed on the auxiliary substrate 400 side do not necessarily have a mirror image relationship. It doesn't matter.

The auxiliary capacitance elements C16, C26, C36, and C46 formed using the auxiliary substrate 400 can also be used for detecting moments Mx and My. For example, as already described, there are several variations in the equations for detecting the moments Mx and My shown in FIG. For example, if only the capacitive element arranged at the center is used for detection,
Mx = (C35 + C45) − (C15 + C25)
My = (C15 + C45)-(C25 + C35)
It is also possible to use formulas relating to variations such as Here, when the auxiliary capacitance elements C16, C26, C36, and C46 are used, this variation is further increased.
Mx = (C35 + C45 + C16 + C26)
-(C15 + C25 + C36 + C46)
My = (C15 + C45 + C26 + C36)
-(C25 + C35 + C16 + C46)
The following formula can also be used.

  As described above, the modification example in which the auxiliary substrate 400 is added is applied to the second embodiment described in §4. However, the embodiment in which the auxiliary substrate 400 is added is the first embodiment described in §3. The same applies to the third embodiment described in the embodiment and §5.

For example, in the force detection device according to the third embodiment, as an expression for detecting the force Fz, FIG.
Fz =-(C15 + C25 + C35 + C45)
However, by providing the auxiliary substrate 400 in the same manner as in the above example, auxiliary capacitance elements C16, C26, C36, and C46 are formed above the capacitance elements C15, C25, C35, and C45, respectively. If you do
Fz = (C16 + C26 + C36 + C46)
-(C15 + C25 + C35 + C45)
This makes it possible to detect the force Fz.

Of course, when the auxiliary substrate 400 is provided in the force detection apparatus according to the third embodiment, the auxiliary capacitance elements C16, C26, C36, and C46 can be used for detecting the moments Mx and My. For example, as an expression for detecting moments Mx and My,
Mx = (C45 + C36) − (C35 + C46)
My = (C15 + C26)-(C25 + C16)
It is also possible to use formulas related to variations such as

  Further, in the above-described modification, the fixed electrode is provided on the auxiliary substrate 400 side so as to correspond to some fixed electrodes E15, E25, E35, and E45 among the 20 fixed electrodes formed on the support 300 side. Although E16, E26, E36, and E46 are provided, more fixed electrodes may be provided. For example, a fixed electrode having a mirror image relationship may be provided on the auxiliary substrate 400 side for all 20 fixed electrodes E11 to E45 on the support 300 shown in FIG. In this case, 20 sets of capacitive elements are formed below the diaphragm, and 20 sets of auxiliary capacitive elements are formed above the diaphragm.

<<< §8. Modified example with auxiliary sensor >>>
In the embodiments described above and the modifications thereof, the sensors for detecting the inclination and displacement of the force transmission body are provided only on the support body side. However, such sensors are also provided on the power reception body side. It is also possible to detect the inclination and displacement of the force transmission body at both ends thereof, and to detect the force and moment based on the detection results on both the support side and the force receiving side. . If such detection is performed, detection operation with higher accuracy becomes possible.

  The modification described here pays attention to such a viewpoint, and further includes an auxiliary sensor that detects a force applied from each force transmission body toward the power receiving body, and the detection processing unit includes the auxiliary sensor. In consideration of the detection result, a process of detecting a force or moment acting on the power receiving body is performed. Such a modification can be applied to any of the first to third embodiments described above and the modifications thereof, but here, a modification applied to the first embodiment is used. A representative example will be described.

  FIG. 31 is a side sectional view showing a basic configuration of a force detection device according to this modification. As can be seen from the comparison with the apparatus according to the first embodiment shown in FIG. 9, the apparatus shown in FIG. 31 is vertically symmetric with respect to the symmetry plane W (horizontal plane) defined in the central part of the apparatus. However, it has a structure that forms a mirror image relationship with respect to the symmetry plane W. Here, for convenience of explanation, the constituent elements that are mirror images of each other and that correspond vertically are assigned the same reference numerals, and “A” is added to the end of the reference numerals of the constituent elements below the symmetry plane W. “B” is added to the end of the reference numerals of components above W.

  Each component below the plane of symmetry W is exactly the same as the component in the lower half of the apparatus according to the first embodiment shown in FIG. That is, the intermediate body 200A having the disk-shaped diaphragms 215A and 225A is joined on the support body 300A. A groove G31A is provided below the diaphragm 215A, and a sensor S1A is formed by a capacitive element group including the fixed electrodes E11A to E15A and the diaphragm 215A. Similarly, a groove G32A is provided below the diaphragm 225A, and a sensor S2A is formed by a capacitive element group constituted by the fixed electrodes E21A to E25A and the diaphragm 225A. A cylindrical projection 210A having a lower end joined to the center of the diaphragm 215A is disposed at the center of the groove G21A provided above the diaphragm 215A, and at the center of the groove G22A provided above the diaphragm 225A. Is provided with a cylindrical protrusion 220A whose lower end is joined to the center of the diaphragm 225A.

  On the other hand, the upper half components disposed above the symmetry plane W form a mirror image of the lower half components. That is, the intermediate body 200B having the disk-shaped diaphragms 215B and 225B is joined under the force receiving body 300B. A groove G31B is provided above the diaphragm 215B, and a sensor S1B is formed by a capacitive element group including the fixed electrodes E11B to E15B and the diaphragm 215B. Similarly, a groove G32B is provided above the diaphragm 225B, and a sensor S2B is formed by a capacitive element group constituted by the fixed electrodes E21B to E25B and the diaphragm 225B. In addition, a cylindrical protrusion 210B whose upper end is joined to the center of the diaphragm 215B is disposed at the center of the groove G21B provided below the diaphragm 215B, and at the center of the groove G22B provided below the diaphragm 225B. Is provided with a cylindrical protrusion 220B whose upper end is joined to the center of the diaphragm 225B. Here, for convenience, the sensors S1B and S2B are referred to as auxiliary sensors.

  The upper ends of the cylindrical protrusions 210A and 220A are joined to the lower ends of the cylindrical protrusions 210B and 220B, respectively, and constitute force transmission bodies T1 and T2. The behavior of the two force transmission bodies T1 and T2 when various force components act on the force receiving body 300B in this force detection apparatus is the same as that of the apparatus according to the first embodiment shown in FIG. The difference is that sensors for detecting the behavior of the force transmission bodies T1 and T2 are provided on both the upper and lower sides. That is, the sensors S1A and S2A function as sensors that detect the force applied from the force transmission bodies T1 and T2 toward the support body 300A, whereas the auxiliary sensors S1B and S2B receive from the force transmission bodies T1 and T2. It functions as a sensor that detects the force applied toward the force body 300B. Here, the force applied from the force transmission bodies T1 and T2 toward the force receiving body 300B is applied as a reaction of the force applied from the force receiving body 300B toward the force transmission bodies T1 and T2.

  Since the sensors S1A and S2A and the auxiliary sensors S1B and S2B have a structure that forms a mirror image relationship with each other, the detection result is also a result based on the mirror image relationship. For example, when force -Fz (pressing force downward in the figure) is applied to the force receiving body 300B, the diaphragm 215A approaches the fixed electrode E15A, and the diaphragm 215B also approaches the fixed electrode E15B. Therefore, the detection result of the sensor S1A and the detection result of the sensor S1B are the same. In other words, the increase / decrease in the capacitance value of the pair of capacitive elements having a mirror image relationship is the same. On the other hand, when a force + Fx (pressing force to the right in the figure) is applied to the force receiving body 300B, the sensor S1A causes the force transmitting body T1 to move in the positive direction of the X axis (right direction in the figure). In contrast to detecting the tilt, the sensor S1B detects that the force transmission body T1 is tilted in the negative X-axis direction (the left direction in the figure). Specifically, the capacitance value of the capacitive element C11A configured by the electrode E11A increases, whereas the capacitance value of the capacitive element C11B configured by the electrode E11B decreases. In other words, the increase / decrease in the capacitance value of the pair of capacitive elements having a mirror image relationship is reversed.

  Therefore, the detection processing unit needs to execute detection processing of each force component in consideration of such a mirror image relationship. For a specific force component, the detection result of the sensor and the detection result of the auxiliary sensor are added. It is necessary to perform an operation for subtracting both results for another force component. However, in principle, the accuracy of the detection result finally obtained is improved by the increase in the number of capacitive elements constituting the sensor.

  In the example shown in FIG. 31, the upper half and the lower half of the apparatus have a completely mirror-image relationship with respect to the symmetry plane W, but the structures of both do not necessarily have a mirror-image relationship. However, regarding the sensor and the auxiliary sensor, it is preferable in practice that the structure of the sensor and the auxiliary sensor is mirror-image-related because the calculation by the detection processing unit becomes easy.

  The modification shown in FIG. 32 is obtained by applying a modification in which the auxiliary sensor described in §8 is further added to the modification in which the auxiliary substrate described in §7 is added. Again, with respect to the symmetry plane W, the upper and lower components are mirror images. The only difference from the apparatus shown in FIG. 31 is that the auxiliary substrates 400A and 400B and the fixed electrodes E16A, E26A, E16B, and E26B are further added and that the shape of the fixed electrode formed on the support 300A side is slightly changed. is there. This modification has both the feature described in §7 and the feature described in §8.

<<< §9. Modified example with conductive material as main material >>>
In the embodiment and the modification described so far, the support 300, 300A or the force receiving body 300B is made of an insulating material. However, these are not necessarily made of an insulating material, such as metal. It may be made of a conductive material. However, in the case of forming a sensor using a capacitive element, some ingenuity is required regarding the formation surface of the fixed electrode. For example, in the case of the apparatus shown in FIG. 31, since an insulating material is used as the support body 300A and the force receiving body 300B, each fixed electrode is formed directly on the upper surface of the support body 300A or the lower surface of the force receiving body 300B. There is no problem. However, if the support body 300A and the force receiving body 300B are made of a conductive material, if each fixed electrode is formed directly on the upper surface of the support body 300A or the lower surface of the force receiving body 300B, the plurality of fixed electrodes are short-circuited to each other. Will end up. In such a case, a fixed electrode may be formed through an insulating layer.

  FIG. 33 is a side sectional view of a modification in which the main material in the force detection device shown in FIG. In this modification, the support body 300C and the intermediate body 200A constituting the lower half of the apparatus are both made of a conductive material such as metal, and the force receiving body 300D and the intermediate body 200B constituting the upper half of the apparatus. Also, it is made of a conductive material such as metal. Therefore, grooves G41A and G42A are dug on the upper surface of the support 300C, and the insulating layers 71A and 72A are fitted and fixed at positions to close the grooves G41A and G42A. The fixed electrodes E11A to E15A and E21A to E25A are formed on the upper surfaces of the insulating layers 71A and 72A. Similarly, groove portions G41B and G42B are dug in the lower surface of the force receiving body 300D, and insulating layers 71B and 72B are fitted and fixed at positions to close the groove portions G41B and G42B. The fixed electrodes E11B to E15B and E21B to E25B are formed on the lower surfaces of the insulating layers 71B and 72B.

  Further, the limiting member described in §6 is also added to the apparatus shown in FIG. That is, four control walls 500 rise from the peripheral upper surface of the support 300C, and surround the outside of the central portion of the apparatus from the four side surfaces. A control groove 510 is formed near the upper side of the inner surface of the control wall 500. On the other hand, a control collar 310 protrudes from the outer peripheral side surface of the plate-shaped force receiving body 300D, and has a structure in which a predetermined gap is accommodated in the control groove 510. The predetermined gap functions to limit the degree of freedom of displacement of the force receiving body 300D. In other words, in any direction of the XYZ three-dimensional coordinate system, when an external force is applied to the force receiving body 300D so as to be displaced beyond a predetermined allowable range, the control collar 310 causes the control groove 510 to A further displacement is controlled by contacting the inner surface.

  In the modification shown in FIG. 33, all the components can be made of a conductive material such as metal except for the insulating layers 71A, 72A, 71B, 72B (for example, can be made of a ceramic plate). It is possible to reduce the manufacturing cost and realize a structure suitable for mass production.

<<< §10. Modification using dummy force transmission body >>>
In the first embodiment described in §3, an example in which two sets of force transmission bodies T1 and T2 are used has been shown. However, in practice, it is better to support a power receiving body using a larger number of force transmission bodies. The stability of mechanical displacement operation is improved. That is, as compared with the first embodiment using two sets of force transmission bodies T1 and T2, as in the second embodiment described in §4 and the third embodiment described in §5, In the embodiment using the force transmission bodies T1 to T4, there is an advantage that the force receiving body can be supported more stably. Of course, in the latter, since detection using four sets of sensors S1 to S4 is performed, there is an advantage that all six force components can be detected.

  The modification described here is an example for providing a force detection device that meets the desire for a structure that stably supports a power receiving body, although it is not necessary to detect all six force components. . In order to meet such a demand, a force transmission body (herein referred to as “dummy force transmission body” for convenience) may be used without a sensor. For example, the force detection device according to the second embodiment described in §4 includes four sets of force transmission bodies as shown in the top view of FIG. It has a function to detect. Here, if it is not necessary to detect a specific force component that requires the detection results of the third sensor S3 and the fourth sensor S4, the force applied from the third and fourth force transmission bodies. Therefore, it is not necessary to provide the electrodes E31 to E35 and the electrodes E41 to E45.

  FIG. 34 is a top view of the support 300 used in such a modification. That is, the structure of this modification is basically the same as the structure of the force detection device according to the second embodiment described in §4. However, instead of the support 300 shown in FIG. The point which used the support body 300 shown in FIG. In other words, although four sets of force transmission bodies T1 to T4 are provided, the sensors are only the first sensor S1 and the second sensor S2, and the third force transmission body T3 and the fourth force transmission are provided. The body T4 is a dummy force transmission body that is not involved in the force detection operation at all.

  After all, in this modified example, the advantage that the force receiving body can be stably supported by the four sets of force transmitting bodies including the two sets of dummy force transmitting bodies T3 and T4 is obtained, and the third sensor is provided. And the fourth sensor becomes unnecessary, so that the work load of the electrode forming process, the wiring process, etc. is reduced, and the merit that the cost can be reduced is also obtained.

  A table showing changes in capacitance values of 10 sets of capacitive elements C11 to C15 and C21 to C25 formed by 10 fixed electrodes E11 to E15 and E21 to E25 shown in FIG. 34 is shown in FIG. ) become that way. In this case, the forces Fx, Fy, Fz, and moment My can be detected by the following principle.

  First, the force Fx is obtained by the equation Fx = (C11−C12) + (C21−C22), the force Fy is obtained by the equation Fy = (C13−C14) + (C23−C24), and the force Fz is Fz = − (C15 + C25). These formulas correspond to formulas excluding some terms of the formulas Fx, Fy, and Fz shown in FIG. The equation in FIG. 20 is an equation when detection is performed using four sets of sensors, whereas the above equation is an equation when detection is performed using two sets of sensors, and the number of terms is It has been reduced to half. Therefore, although the detection accuracy is slightly lowered, in principle, the forces Fx, Fy, and Fz can be detected without any problem. Note that the force Fz can be detected by a variation of, for example, Fz = − ((C11 + C12 + C13 + C14 + C15) + (C21 + C22 + C23 + C24 + C25)), as already described.

  On the other hand, the moment My is an expression of My = ((C11 + C12 + C13 + C14 + C15) − (C21 + C22 + C23 + C24 + C25)), or a variation thereof (C15−C25). It can be obtained by an expression.

  As described above, in the modification using the support body 300 shown in FIG. 34, the forces Fx, Fy, Fz and the moment My can be detected, but the moments Mx, Mz cannot be detected. Also, the moment Mx and the force Fz cannot be distinguished (when the moment Mx acts, the moment Fx is detected as the force Fz), and the moment Mz and the force Fx cannot be distinguished (moment Mz Is detected as the force Fx by the above formula). For this reason, this modification cannot be used in an environment in which moments Mx and Mz are applied.

  In the modification using the support body 300 shown in FIG. 34, the third sensor S3 and the fourth sensor S4 are excluded from the embodiment (second embodiment) using the support body 300 shown in FIG. Thus, although the third force transmission body T3 and the fourth force transmission body T4 are used as dummy force transmission bodies, the embodiment using the support body 300 shown in FIG. 3), the third force transmission body T3 and the fourth force transmission body T4 are used as dummy force transmission bodies by removing the third sensor S3 and the fourth sensor S4. Is also possible. The detection operation of such a modification is the same as the detection operation of the embodiment (first embodiment) using the support 300 shown in FIG.

<<<< §11. Fourth embodiment of the present invention >>>
Finally, a force detection device according to a fourth embodiment of the present invention will be described. In the first embodiment described in §3, detection is performed using two sets of force transmission bodies T1 and T2 and two sets of sensors S1 and S2, and in the second embodiment and §5 described in §4. In the described third embodiment, detection using four sets of force transmission bodies T1 to T4 and four sets of sensors S1 to S4 was performed. In the fourth embodiment described here, detection using three sets of force transmission bodies T1 to T3 and three sets of sensors S1 to S3 is performed. Therefore, the structures of the force receiving body, the support body, and each columnar force transmission body in the force detection device according to the fourth embodiment are exactly the same as those of the previous embodiments. However, the number and arrangement of the columnar force transmission bodies are only slightly different. Only this difference will be described below.

  FIG. 35 is a top view of the support body 300 used in the force detection device according to the fourth embodiment. Compared with FIG. 18, which is a top view of the support 300 used in the force detection device according to the second embodiment described above, the difference between the two becomes clear. That is, in the second embodiment, as shown in FIG. 18, the fixed electrodes E11 to E15, E21 to E25, E31 to E35, and E41 to E45, which are the constituent elements of the four sets of sensors S1 to S4, The first to fourth quadrants in the system are arranged, and the first to fourth force transmission bodies T1 to T4 are arranged in the first to fourth quadrants in the XY two-dimensional coordinate system, respectively.

  On the other hand, in the force detection device according to the fourth embodiment shown in FIG. 35, the fixed electrodes E11 to E15, E21 to E25, and E31 to E35 that are constituent elements of the three sets of sensors S1 to S3 are xy two. In the dimensional coordinate system, they are arranged in the positive part of the y-axis, the third quadrant, and the fourth quadrant, respectively. After all, each of the first to third columnar force transmission bodies T1 to T3 is configured by a structure having the longitudinal direction in the Z-axis direction, and the longitudinal direction of the first force transmission body T1 is the Y-axis. The second force transmission body T2 is disposed in the third quadrant of the XY plane, and the third force transmission body is disposed in the fourth quadrant of the XY plane. . The capacitive elements C11 to C15, C21 to C25, and C31 to C35 are formed by the fixed electrodes E11 to E15, E21 to E25, E31 to E35, and the conductive diaphragms (common displacement electrodes) located thereabove. This is the same as the second embodiment described above. However, since the arrangement of the force transmission body and the sensor is different, the detection processing by the detection processing unit 30 is slightly different.

  FIG. 36 is a table showing changes in electrostatic capacitance values of the capacitive elements C11 to C35 in the force detection device according to the fourth embodiment. Also in this table, only the case where the values of the six force components Fx, Fy, Fz, Mx, My, and Mz are positive is shown, but if it is negative, the increase / decrease relationship is only reversed. When the table shown in FIG. 36 is compared with the table shown in FIG. 19 for the second embodiment, the capacitive elements C11 to C15 and C21 to C25 when the force components Fx, Fy, and Fz in the respective axial directions are applied. , C31 to C35 have exactly the same change in capacitance value. Therefore, the detection principle regarding the force components Fx, Fy, and Fz in the respective axial directions is the same as in the case of the second embodiment described above. However, in the case of the second embodiment described above, the force components Fx, Fy, and Fz in the respective axial directions are detected as the sum of the detection results of the four sets of sensors S1 to S4, but are shown here. In the case of the fourth embodiment, detection as the sum of the detection results by the three sets of sensors S1 to S3 is performed, and the detection accuracy slightly decreases.

  On the other hand, the manner in which the capacitance value of each capacitive element changes when the moments Mx, My, and Mz around each axis are applied is slightly different from that in the second embodiment. Therefore, the principle of detecting these moments will be briefly described below.

  First, when the moment Mx around the X axis is applied, as can be seen by referring to the plan view of FIG. 35, the first force transmission body T1 (the fixed electrode E15 of the figure) arranged in the positive portion of the Y axis is understood. A tensile force (+ fz) acts on the support 300 from the second force transmission body T2 (disposed on the fixed electrode E25 in the figure) disposed in the third quadrant. ) And the third force transmission body T3 (located on the fixed electrode E35 in the figure) arranged in the fourth quadrant, a pressing force (−fz) acts on the support body 300. As a result, a result as shown in the fourth row (+ Mx row) in FIG. 36 is obtained.

  On the other hand, when the moment My around the Y axis acts, a tensile force (+ fz) acts on the support body 300 from the second force transmission body T2 arranged in the third quadrant, and is arranged in the fourth quadrant. Further, a pressing force (−fz) acts on the support body 300 from the third force transmission body T3. At this time, no significant force is applied to the support 300 from the first force transmission body T1 disposed in the positive portion of the Y-axis. As a result, a result as shown in the fifth row (+ My row) in FIG. 36 is obtained.

  Next, referring to FIG. 35, when a positive moment about the Z axis + Mz (which is a counterclockwise moment on the plan view of FIG. 35) is applied to the force receiving member 100, three sets of forces are applied. Let us consider in which direction the transmission bodies T1 to T3 are inclined.

  First, the first force transmission body T1 (located on the fixed electrode E15 in the figure) disposed in the positive portion of the Y axis is inclined in the left direction (negative direction of the x axis) in FIG. As a result, the electrode interval of the capacitive element C12 is reduced and the capacitance value is increased, and the electrode interval of the capacitive element C11 is increased and the capacitance value is reduced. Further, the second force transmission body T2 arranged in the third quadrant (arranged on the fixed electrode E25 in the figure) is inclined in the lower right direction in FIG. The electrode interval of C24 is reduced and the capacitance value is increased, and the electrode interval of the capacitive elements C22 and C23 is increased and the capacitance value is decreased. Finally, the third force transmission body T3 (located on the fixed electrode E35 in the figure) arranged in the fourth quadrant is inclined in the upper right direction in FIG. The electrode interval of C33 is reduced and the capacitance value is increased, and the electrode interval of the capacitive elements C32 and C34 is increased and the capacitance value is decreased. Note that the capacitance values of the capacitive elements C13, C14, C15, C25, and C35 do not change in total.

  Eventually, when a positive moment + Mz around the Z-axis acts on the force receiving body 100, an increase / decrease result as shown in the sixth line of FIG. 36 is obtained. Of course, when a negative moment -Mz around the Z-axis acts on the force receiving member 100, a result obtained by reversing the positive / negative relationship with this is obtained.

  Taking into account that the results shown in the table of FIG. 36 are obtained, as the detection processing unit 30, the capacitance values of the 15 sets of capacitive elements C11 to C35 (here, the capacitance values themselves are the same). If a processing device that performs a calculation based on the equation shown in FIG. 37 using a circuit for measuring (denoted by C11 to C35) and each measured capacitance value is prepared, Fx, Fy, Six components of Fz, Mx, My, and Mz can be obtained. Here, the expressions for Fx, Fy, and Fz shown in FIG. 37 are obtained by excluding the terms related to the fourth sensor from the corresponding expressions shown in FIG.

  On the other hand, the equation Mx = − ((2 × C15) − (C25 + C35)) shown in FIG. 37 is based on the result of the fourth row (+ Mx row) of the table of FIG. A moment Mx about the X-axis of the force acting on the force receiving body based on the difference between the force in the Z-axis direction detected by the sensor and the force in the Z-axis direction detected by the second and third sensors. Means that it can be detected. The minus sign at the beginning of the formula is due to the direction of the moment. The reason why the term C15 is multiplied by the coefficient 2 is to adjust the detection sensitivity of each sensor.

  That is, as apparent from the plan view of FIG. 35, when the moment Mx around the X axis is applied, the force generated in the upper half region (first quadrant and second quadrant of the xy two-dimensional coordinate system). The phenomenon relating to the action of the force and the phenomenon relating to the action of the force generated in the lower half region (the third and fourth quadrants of the xy two-dimensional coordinate system) are physically opposite phenomena. In the above equation, the difference between the capacitance values is finally obtained because of such a reverse physical phenomenon. However, as shown in FIG. 35, the sensor responsible for detecting the physical phenomenon in the upper half area is only the first sensor (capacitance element C15 in this example), whereas the physical sensor in the lower half area. There are two sets of sensors responsible for detecting the phenomenon: a second sensor (capacitance element C25 in this example) and a third sensor (capacitance element C35 in this example). For this reason, the detection sensitivity in the lower half region is doubled with respect to the detection sensitivity in the upper half region. The reason why the coefficient C2 is multiplied by the term C15 in the Mx equation is to correct such a difference in detection sensitivity.

  In addition, it can replace with the correction which multiplies such a coefficient and can also correct | amend the area of a fixed electrode. For example, in the example shown in FIG. 35, the fixed electrodes E15, E25, and E35 are circular electrodes of the same size, but are appropriately modified so that the diameter of the fixed electrode E15 is larger than the diameter of the fixed electrodes E25 and E35. If the area of the fixed electrode E15 is set to be twice the area of the fixed electrodes E25 and E35, the detection sensitivity of the capacitive element C15 becomes twice the detection sensitivity of the capacitive element C25 or C35. The coefficient 2 multiplied by the term of C15 in the Mx equation of FIG.

  Subsequently, the formula of the moment My will be described. The formula My = (C35-C25) shown in FIG. 37 is based on the result of the fifth row (+ My row) of the table of FIG. 36, and relates to the Z-axis direction detected by the third sensor. This means that the moment My around the Y-axis of the force acting on the force receiving body can be detected based on the difference between the force and the force in the Z-axis direction detected by the second sensor.

  Finally, the equation Mz = ((C21−C22) + (C31−C32) −2 × (C11−C12)) + ((C33−C34) − (C23−C24)) shown in FIG. This is based on the result of the sixth row (+ Mz row) of the table, and is detected by the first sensor from the sum of the gradients in the X-axis direction detected by the second and third sensors. The difference obtained by subtracting the inclination in the X-axis direction is obtained as the first difference, and the inclination in the Y-axis direction detected by the second sensor is subtracted from the inclination in the Y-axis direction detected by the third sensor. This means that the difference Mm is obtained as the second difference, and based on the sum of the first difference and the second difference, the moment Mz around the Z-axis of the force acting on the force receiving body can be detected.

The meaning of this Mz equation is
Mz = -2 * (C11-C12)
+ (C21 + C24)-(C22 + C23)
+ (C31 + C33)-(C32 + C34)
If you rewrite it like this, it will be easier to understand. That is, when a positive moment + Mz around the Z-axis is applied, as described above, in FIG. 35, the first force transmission body T1 disposed on the fixed electrode E15 is inclined in the left direction in the figure. However,-(C11-C12) in the above equation is a term for detecting such an inclination of the first force transmission body T1. Similarly, the second force transmission body T2 disposed on the fixed electrode E25 is inclined in the lower right direction in the figure, but the above equation (C21 + C24) − (C22 + C23) is This is a term for detecting such an inclination of the force transmission body T2. Further, the third force transmission body T3 disposed on the fixed electrode E35 is inclined in the upper right direction in the figure, but the above formula (C31 + C33) − (C32 + C34) is the third force transmission. This is a term for detecting such an inclination of the body T3. Thus, the above equation shows the sum of the detected values of the inclination in the predetermined direction of the three force transmission bodies T1 to T3 when the moment Mz about the Z-axis acts.

  In this Mz equation, the term (C11-C12) is multiplied by the coefficient 2 in order to adjust the detection sensitivity of each sensor. That is, in order to correct the detection sensitivity of the first sensor S1 to be twice that of the second sensor S2 or the third sensor S3, the detection result of the first sensor S1 is obtained (C11). −C12) is multiplied by a factor of 2. The reason why such a correction is necessary is, as can be seen from the plan view of FIG. 35, when attention is paid to the detection operation of the inclination in the X-axis direction, the sensor that handles the upper half region is the first sensor (this example In this case, only the capacitive elements C11 and C12), while the sensors responsible for the lower half region are the second sensor (in this example, the capacitive elements C21 and C22) and the third sensor (in this example). This is because there are two sets of capacitive elements C31 and C32). Of course, if the area of the fixed electrodes E11 and E12 is set to be twice the area of the fixed electrodes E21, E22, E31, and E32, correction by multiplying such a coefficient is not necessary. It should be noted that the tilt detection operation in the Y-axis direction only requires a difference between the detection result of the third sensor and the detection result of the second sensor, so that such correction is unnecessary. .

  By the way, as described many times so far, there are a plurality of variations in the method for obtaining the force in the Z-axis direction of each of the force transmission bodies T1 to T3, and each equation shown in FIG. It is also possible to apply these variations. For example, the expression of the force Fz in FIG. 37 may be Fz = − ((C11 + C12 + C13 + C14 + C15) + (C21 + C22 + C23 + C24 + C25) + (C31 + C32 + C33 + C34 + C35)). The expression of the force Mx can also be − ((2 × (C11 + C12 + C13 + C14 + C15)) − ((C21 + C22 + C23 + C24 + C25) + (C31 + C32 + C33 + C34 + C35))). Similarly, the formula for the force My can also be (C31 + C32 + C33 + C34 + C35) − (C21 + C22 + C23 + C24 + C25).

  As mentioned above, although the example which uses 3 sets of force transmission bodies was described as 4th Embodiment, of course, it is possible to apply the modification described in §6 to §11 also to this 4th embodiment. It is.

<<<< §12. Other variations >>
As described above, the present invention has been described based on the illustrated embodiments and modifications. However, the present invention is not limited to these embodiments and modifications, and can be implemented in various other modes.

  For example, in the above-described embodiment, the multi-axis force sensor of the type shown in FIG. 3 is incorporated in the connection portion between each force transmission body and the support, but the force sensor incorporated in the present invention is not necessarily shown in FIG. There is no need to use such a capacitance type, and for example, a piezoresistive force sensor, a force sensor using a piezoelectric element, or the like may be used. Further, even when a capacitive force sensor is used, it is not always necessary to use a type that uses the diaphragm 51 itself as a common displacement electrode as shown in FIG. When the diaphragm 51 is made of an insulating material, a conductive film can be formed on the lower surface of the diaphragm 51 and used as a common displacement electrode. Of course, instead of providing only one common displacement electrode, an individual displacement electrode facing each fixed electrode may be provided.

  In the above-described embodiment, a connecting member having flexibility (specifically, a thin portion of a plate-shaped power receiving body) is provided at a connection portion between each force transmitting body and the power receiving body. The upper end of each force transmission body does not necessarily need to be connected to the force receiving body via a flexible connecting member. As long as the force or moment to be detected can be applied to the power receiving body without any problem, the upper end of each force transmitting body may be directly connected to the power receiving body and fixed. In practice, however, the upper end of each force transmission body is flexible so that the force and moment to be detected can be applied to the power receiving body without hindrance, as in the embodiments described above. It is preferable that each force transmission body is connected to the force receiving body via a connecting member so that each force transmitting body can be displaced with a certain degree of freedom.

  In addition, the detection processing unit 30 that performs the function of obtaining the detection value of the final force or moment can be actually realized with various configurations. For example, the capacitance value of each capacitive element is measured as an analog voltage value, and the measured value is converted into a digital signal. Then, using an arithmetic unit such as a CPU, FIG. 14, FIG. 20, FIG. It is also possible to adopt a method of executing the calculation shown in the equation of (1), handle the measured value of the capacitance value of each capacitive element as an analog voltage value, and output the final detected value as an analog signal. It is also possible to adopt the method. In the case of adopting the latter method, predetermined wiring may be provided to the electrodes of the respective capacitive elements, and connected to an analog arithmetic circuit including an analog adder and an analog subtracter as necessary. Further, an arithmetic circuit is not necessarily required to obtain the sum of the capacitance values. For example, in order to obtain the sum of the capacitance values of two capacitive elements C1 and C2, it is sufficient to provide a wiring connecting these two capacitive elements in parallel and obtain the capacitance value between two points on the wiring. . As described above, the detection processing unit in the present invention is not necessarily configured by a digital or analog arithmetic circuit, and can be configured by a wiring that electrically connects a plurality of capacitive elements. The term “processing unit” is a concept including such simple electric wiring.

  In the embodiments described so far, the two or four force transmission bodies and the connection members thereof are located symmetrically in a coordinate system having an origin at the center of the square force receiving body 100 (a line with respect to a specific coordinate axis). They are all of the same material and size, but they do not necessarily have to be placed symmetrically, and they need to be of the same material and size. Absent. Of course, it is not necessary to prepare the same sensors. For example, in the second embodiment, four force transmission bodies are arranged at the four vertex positions of a square, but in principle, four force transmissions are required to detect six components of force. As long as the body is not arranged in a straight line, the arrangement of the four force transmission bodies may be arbitrary. However, if the four force transmission bodies are not symmetrically arranged with respect to the coordinate system, the materials and sizes are not the same, or the structures and sizes of the individual sensors are different, A difference occurs in the detection sensitivity of the element, and when performing the calculation shown in the equations of FIGS. 14, 20, and 23, it is necessary to multiply each capacitance value by a specific sensitivity coefficient. It is preferable to adopt the above-described embodiment.

  In this application, for convenience of explanation, the terms “power receiving body” and “support body” are used, but this is intended to be a general usage mode in which the support body is fixed and the force to be detected is applied to the power receiving body. It is a thing. However, the utilization form of the force detection device according to the present invention is not limited to such a form, and conversely, the force receiving body is fixed and the force to be detected is applied to the support body. Usage forms are also possible. In general, the force detection device has a function of detecting a force acting on the second portion in a state where the first portion is fixed, and a force acting on the force receiving body in a state where the support is fixed. The event of detecting is essentially the same as the event of detecting the force acting on the support while the force receiving member is fixed. Therefore, in the first to third embodiments described above, the sensor for detecting the inclination and displacement of the force transmission body is provided on the support body side. However, such a sensor is not provided on the support body side but on the power receiving body side. The technical idea that it is provided in is essentially the same technical idea as the present invention, and is included in the scope of the present invention.

10: force receiving body 11: first force transmitting body 12: second force transmitting body 20: support body 21: first sensor 22: second sensor 30: detection processing unit 40: support body 50: bowl-shaped Connection member 51: Diaphragm (common displacement electrode)
52: Side wall part 53: Fixing part 60: Force transmission body 71A, 72A: Insulating layer 71B, 72B: Insulating layer 100: Power receiving body 110: Columnar protruding part 115: Thin part 120: Columnar protruding part 125: Thin part 130: Columnar projection 135: Thin portion 140: Columnar projection 145: Thin portion 150: Columnar projection 200: Intermediate 200A, 200B: Intermediate 210: Columnar projection 210A, 210B: Columnar projection 215: Diaphragm 215A, 215B: Diaphragm 220: cylindrical protrusions 220A, 220B: cylindrical protrusion 225: diaphragm 225A, 225B: diaphragm 230: cylindrical protrusion 235: diaphragm 240: cylindrical protrusion 245: diaphragm 250: control wall 260: control collar 300: support Body 300A: Support 300B: Power receiving body 300C: Support 300D: Power receiving 310: Control collar 400: Auxiliary substrate 400A, 400B: Auxiliary substrate 500: Control wall 510: Control grooves C11-C45: Capacitance elements / capacitance element capacitance values d1, d2, d3: Control dimensions E1-E5 , E11 to E45: Fixed electrodes E11A to E25A: Fixed electrodes E11B to E25B: Fixed electrodes Fx, Fx ′: Force fx in the X-axis direction, fx ′: Force in the x-axis direction Fy: Force in the Y-axis direction Fz: Z-axis Directional force fz: Tensile force / pressing force acting on the support G11 to G34: Groove parts G21A to G42A: Groove parts G21B to G42B: Groove parts H1 to H4: Opening Mx: Moment around X axis My: Around Y axis Moment Mz: Moment about Z axis O: Origin P1 to P4 of coordinate system: Points S1 to S4 on force receiving body 100: Multiaxial force sensor S1A, S2A: Multiaxial force sensor S1B, 2B: auxiliary sensors T1 to T4: force transmission body W: symmetry plane XYZ: coordinate system having an origin at the center position of the force receiving body xy: coordinate system θ1, θ2 defined on the upper surface of the support body: force transmission body 11, 12 tilt angles

Claims (14)

A force detection device for detecting a moment Mz about the Z axis in an XYZ three-dimensional coordinate system,
  A force receiving body made of a plate-like member arranged at the origin position of the coordinate system to receive a force to be detected and extending along the XY plane;
  A support body composed of a plate-like member disposed below the force receiving body and extending along a plane parallel to the XY plane;
  A structure in which the upper end is connected to the power receiving body through a flexible connecting member, the lower end is connected to the support through a flexible connecting member, and the Z-axis direction is the longitudinal direction A first force transmission body constituted by a body;
  A structure in which the upper end is connected to the power receiving body through a flexible connecting member, the lower end is connected to the support through a flexible connecting member, and the Z-axis direction is the longitudinal direction A second force transmission body constituted by a body;
  A first sensor having a function of detecting an inclination of the first force transmission body with respect to the support body in the Y-axis direction;
  A second sensor having a function of detecting an inclination of the second force transmission body in the Y-axis direction with respect to the support;
  In consideration of the detection results of the first and second sensors, a detection processing unit that performs a process of detecting a moment acting on the force receiving body;
  With
  The first and second force transmission bodies are constituted by columnar members, the connection member is constituted by a diaphragm, and the lower surfaces of the first and second force transmission bodies are fixed to the support body at the periphery. Bonded to the center of the diaphragm, and the upper surfaces of the first and second force transmission bodies are bonded to the center of the diaphragm, the periphery of which is fixed to the force receiving body,
  The first and second sensors include a fixed electrode fixed to the upper surface of the support and a displacement electrode fixed to a displacement surface of a diaphragm joined to the lower surface of the force transmission body. It has an element and performs detection based on the capacitance value of this capacitive element,
  The first force transmission body is disposed at a position where the longitudinal direction of the first force transmission body intersects with the positive portion of the X axis, and the second force transmission body is disposed at a position where the longitudinal direction of the second force transmission body intersects with the negative portion of the X axis.
  The force that the detection processing unit has acted on the force receiving member based on the difference between the inclination in the Y-axis direction detected by the first sensor and the inclination in the Y-axis direction detected by the second sensor A force detection device that performs a process of detecting a moment Mz about the Z-axis. A force detection device for detecting a moment My about the Y axis in an XYZ three-dimensional coordinate system,
  A force receiving body made of a plate-like member arranged at the origin position of the coordinate system to receive a force to be detected and extending along the XY plane;
  A support body composed of a plate-like member disposed below the force receiving body and extending along a plane parallel to the XY plane;
  A structure in which the upper end is connected to the power receiving body through a flexible connecting member, the lower end is connected to the support through a flexible connecting member, and the Z-axis direction is the longitudinal direction A first force transmission body constituted by a body;
  A structure in which the upper end is connected to the power receiving body through a flexible connecting member, the lower end is connected to the support through a flexible connecting member, and the Z-axis direction is the longitudinal direction A second force transmission body constituted by a body;
  A first sensor having a function of detecting a force in the Z-axis direction applied from the first force transmission body to the support;
  A second sensor having a function of detecting a force in the Z-axis direction applied from the second force transmission body to the support;
  In consideration of the detection results of the first and second sensors, a detection processing unit that performs a process of detecting a moment acting on the force receiving body;
  With
  The first and second force transmission bodies are constituted by columnar members, the connection member is constituted by a diaphragm, and the lower surfaces of the first and second force transmission bodies are fixed to the support body at the periphery. Bonded to the center of the diaphragm, and the upper surfaces of the first and second force transmission bodies are bonded to the center of the diaphragm, the periphery of which is fixed to the force receiving body,
  The first and second sensors include a fixed electrode fixed to the upper surface of the support and a displacement electrode fixed to a displacement surface of a diaphragm joined to the lower surface of the force transmission body. It has an element and performs detection based on the capacitance value of this capacitive element,
  The first force transmission body is disposed at a position where the longitudinal direction of the first force transmission body intersects with the positive portion of the X axis, and the second force transmission body is disposed at a position where the longitudinal direction of the second force transmission body intersects with the negative portion of the X axis.
  Y of the force acting on the force receiving body based on the difference between the force in the Z-axis direction detected by the first sensor and the force in the Z-axis direction detected by the second sensor. A force detection device that performs a process of detecting a moment My about an axis. A force detection device for detecting forces Fx, Fz in the direction of each coordinate axis and moments Mx, My around each coordinate axis in an XYZ three-dimensional coordinate system,
  A force receiving body made of a plate-like member arranged at the origin position of the coordinate system to receive a force to be detected and extending along the XY plane;
  A support body composed of a plate-like member disposed below the force receiving body and extending along a plane parallel to the XY plane;
  A structure in which the upper end is connected to the power receiving body through a flexible connecting member, the lower end is connected to the support through a flexible connecting member, and the Z-axis direction is the longitudinal direction A first force transmission body constituted by a body;
  A structure in which the upper end is connected to the power receiving body through a flexible connecting member, the lower end is connected to the support through a flexible connecting member, and the Z-axis direction is the longitudinal direction A second force transmission body constituted by a body;
  A function of detecting an inclination of the first force transmission body with respect to the support in the X-axis direction, a function of detecting an inclination of the first force transmission body with respect to the support in the Y-axis direction; A first sensor having a function of detecting a force in the Z-axis direction applied to the support from one force transmission body;
  A function of detecting an inclination of the second force transmission body in the X-axis direction with respect to the support, a function of detecting an inclination of the second force transmission body in the Y-axis direction with respect to the support, and the first A second sensor having a function of detecting a force in the Z-axis direction applied to the support from two force transmission bodies;
  In consideration of the detection results of the first and second sensors, a detection processing unit that performs a process of detecting a force and a moment acting on the force receiving body;
  With
  The first and second force transmission bodies are constituted by columnar members, the connection member is constituted by a diaphragm, and the lower surfaces of the first and second force transmission bodies are fixed to the support body at the periphery. Bonded to the center of the diaphragm, and the upper surfaces of the first and second force transmission bodies are bonded to the center of the diaphragm, the periphery of which is fixed to the force receiving body,
  The first and second sensors include a fixed electrode fixed to the upper surface of the support and a displacement electrode fixed to a displacement surface of a diaphragm joined to the lower surface of the force transmission body. It has an element and performs detection based on the capacitance value of this capacitive element,
  The first force transmission body is disposed at a position where the longitudinal direction of the first force transmission body intersects with the positive portion of the X axis, and the second force transmission body is disposed at a position where the longitudinal direction of the second force transmission body intersects with the negative portion of the X axis.
  The detection processing unit
  The X-axis direction component of the force acting on the force receiving body based on the sum of the inclination degree in the X-axis direction detected by the first sensor and the inclination degree in the X-axis direction detected by the second sensor Perform processing to detect Fx,
  Based on the sum of the force related to the Z-axis direction detected by the first sensor and the force related to the Z-axis direction detected by the second sensor, the Z-axis direction component Fz of the force acting on the force receiving body is calculated. Process to detect,
  A moment Mx about the X-axis acting on the force receiving member based on the sum of the inclination in the Y-axis direction detected by the first sensor and the inclination in the Y-axis direction detected by the second sensor Process to detect,
  Based on the difference between the force in the Z-axis direction detected by the first sensor and the force in the Z-axis direction detected by the second sensor, the moment My around the Y-axis of the force acting on the force receiving body A force detection device characterized by performing a process for detecting the pressure. The force detection device according to claim 3,
  The force that the detection processing unit has acted on the force receiving member based on the difference between the inclination in the Y-axis direction detected by the first sensor and the inclination in the Y-axis direction detected by the second sensor A force detection apparatus further comprising a process of detecting a moment Mz about the Z axis. In the force detection device according to any one of claims 1 to 4 ,
A diaphragm having flexibility and conductivity is used as a connecting member on the lower surface side of the force transmission body, the lower surface of the force transmission body is joined to the center of the diaphragm, and the periphery of the diaphragm is fixed to the support body, thereby A force detection device characterized in that a transmission body is connected to a support and the diaphragm itself is used as a displacement electrode. The force detection device according to claim 5 ,
When defining an xy two-dimensional coordinate system with the origin at the intersection of the extension line of the axis of the force transmission body made of a columnar member and the upper surface of the support,
The first fixed electrode and the second fixed electrode are disposed on the positive part and the negative part of the x-axis on the upper surface of the support, respectively, and the first fixed electrode and the negative part of the y-axis on the upper surface of the support are respectively arranged on the positive and negative parts. 3 fixed electrodes and a fourth fixed electrode,
The displacement electrode made of a diaphragm and the first to fourth fixed electrodes constitute first to fourth capacitance elements, and the capacitance value of the first capacitance element and the capacitance of the second capacitance element. Based on the difference between the values, the inclination of the force transmission body in the x-axis direction is detected, and based on the difference between the capacitance value of the third capacitance element and the capacitance value of the fourth capacitance element, A force detection apparatus that detects a degree of inclination of a force transmission body in the y-axis direction, and a detection processing unit performs a process of detecting a force or a moment using these detection results. The force detection device according to claim 6 , wherein
A fifth fixed electrode is further arranged in the vicinity of the origin on the upper surface of the support, and a fifth capacitive element is constituted by the displacement electrode made of a diaphragm and the fifth fixed electrode. Based on the capacitance value, the force applied to the support from the force transmission body is detected, and the detection processing unit performs processing for detecting force or moment using the detection result. Force detection device. In the force detection device according to any one of claims 5 to 7 ,
An opening for inserting the force transmission body, and an auxiliary substrate fixed to the support so as to be disposed above the diaphragm used as a connection member on the lower surface side of the force transmission body ;
The sensor has an auxiliary capacitance element composed of a fixed electrode fixed to the lower surface of the auxiliary substrate and a displacement electrode made of the diaphragm itself, and the detection processing unit has a capacitance value of the auxiliary capacitance element. A force detection device that detects force or moment by using. The force detection device according to claim 8 , wherein
A force detection apparatus, wherein a part or all of the fixed electrodes fixed to the lower surface of the auxiliary substrate form a mirror image relationship with part or all of the fixed electrodes fixed to the upper surface of the support. In the force detection device according to any one of claims 1 to 9 ,
The force detection device, wherein the detection processing unit is configured by wiring for electrically connecting a plurality of capacitive elements. In the force detection device according to any one of claims 1 to 10 ,
A force detection device characterized in that a connecting member for connecting a force receiving body and a force transmitting body is constituted by a thin portion of a plate-shaped force receiving body. In the force detection device according to any one of claims 1 to 10 ,
An auxiliary sensor for detecting the force applied from each force transmitting body toward the power receiving body is further provided,
A force detection device, wherein the detection processing unit performs processing for detecting a force or a moment acting on the force receiving body, further considering a detection result of the auxiliary sensor. The force detection device according to claim 12 ,
A sensor that detects a force applied from the force transmission body toward the support body and an auxiliary sensor that detects a force applied from the force transmission body toward the power receiving body have a mirror image relationship;
A force detection device, wherein a detection processing unit executes processing in consideration of the mirror image relationship. In the detection apparatus in any one of Claims 1-13 ,
A force detection device comprising a restriction member for restricting displacement of a force receiving body with respect to a support within a predetermined range.

Images