CN116893025A - Force sensor device and mechanical arm - Google Patents

Abstract

The invention provides a force sensor device and a mechanical arm, which can reduce the change of the output of a sensor chip caused by stress generated when the force sensor device is mounted on a fixed part. The force sensor device is provided with: a sensor chip; a first component having: a sensor chip mounting portion including a plurality of first contact portions, and mounted with the sensor chip; a tube portion connected to the first fixing portion; and a flange protruding from the cylindrical portion and formed with a bolt hole; and a second member having: a second contact portion that contacts the sensor chip; a support portion that supports the second contact portion; a second beam extending radially from the support portion; and a second fixing portion that is coupled to the second beam and is fixed to the first fixing portion, the flange including an abutment surface that protrudes from an end surface of the cylindrical portion.

Description

Force sensor device and mechanical arm

Technical Field

The present invention relates to a force sensor device and a robot arm.

Background

Conventionally, a force sensor device is known in which a plurality of strain gauges are attached to a strain body made of metal, and the strain gauge converts the strain when an external force is applied into an electrical signal to detect a force of multiple axes. However, since the force sensor device requires a single strain gauge to be attached by manual operation, there are problems in terms of accuracy and productivity, and it is difficult to miniaturize the structure.

On the other hand, a force sensor device has been proposed in which a problem of bonding accuracy is eliminated and miniaturization is achieved by replacing a strain gauge with a sensor chip of a MEMS (Micro Electro Mechanical Systems: microelectromechanical system) for strain detection (for example, refer to patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent No. 4011345

Disclosure of Invention

Problems to be solved by the invention

The force sensor device is attached to a component to be connected using, for example, a screw. It is difficult to completely flatten the mounting surface of the force sensor device and the mounting surface of the connection object component, and a gap is generated between the force sensor device and the connection object component. If the strain body is deformed by the stress generated when the screw is tightened, the deformation is transmitted to the sensor chip. Therefore, the output of the sensor chip is subject to change (offset).

The invention provides a force sensor device and a mechanical arm, which can reduce deflection caused by stress generated during installation of the force sensor device.

Means for solving the problems

The force sensor device of the present invention comprises:

a sensor chip that detects displacement in at least one of a plurality of axial directions;

A first component having: a sensor chip mounting portion including a first contact portion that contacts the sensor chip and mounting the sensor chip; a force receiving portion connected to the sensor chip mounting portion; a first beam extending from the sensor chip mounting portion in a radial direction of an imaginary circle centered on the sensor chip mounting portion; a first fixing portion connected to the first beam; a tube portion connecting the first fixing portion; and a flange protruding from the cylindrical portion and formed with a bolt hole; and

a second component having: a second contact portion that contacts the sensor chip; a support portion that supports the second contact portion; a second beam extending from the support portion in the radial direction; and a second fixing portion connected to the second beam and fixed to the first fixing portion,

the flange includes an abutment surface that protrudes from an end surface of the barrel portion.

The mechanical arm of the present invention comprises:

the force sensor device described above; and

an arm body connected to the force sensor device.

Effects of the invention

The invention can reduce deflection caused by stress generated during installation of a force sensor device.

Drawings

Fig. 1 is a side view showing a robot arm to which a force sensor device according to an embodiment is attached.

Fig. 2 is a cross-sectional view showing a fitting and a force sensor device attached to the distal end portion of the arm body.

Fig. 3 is a diagram showing the orientations of the X-axis, the Y-axis, the Z-axis, the force Fx along the X-axis, the force Fy along the Y-axis, the force Fz along the Z-axis, the moment Mx about the X-axis, the moment My about the Y-axis, and the moment Mz about the Z-axis.

Fig. 4 is a perspective view showing the force sensor apparatus from above.

Fig. 5 is a plan view showing the force sensor apparatus.

Fig. 6 is a perspective view showing a cross section of the force sensor device, and is a view showing a cut surface intersecting the X-axis and the Y-axis.

Fig. 7 is a perspective view showing a cross section of the force sensor apparatus, and is a view showing a cross section along the Y-axis and the Z-axis.

Fig. 8 is a cross-sectional view showing the force sensor apparatus, and is a view showing a cross-section along the Y-axis and the Z-axis.

Fig. 9 is a cross-sectional perspective view showing a first component of the force sensor apparatus.

Fig. 10 is a plan view showing a first component of the force sensor apparatus.

Fig. 11 is a perspective view showing the force sensor apparatus from below.

Fig. 12 is an enlarged plan view of the sensor chip mounting portion showing the first member of the force sensor device.

Fig. 13 is a perspective view showing a sensor chip mounting portion of a first member of the force sensor device.

Fig. 14 is a top view of the first beam showing the first component of the force sensing sensor assembly.

Fig. 15 is a cross-sectional view showing a cylindrical portion of a first member of the force sensor device.

Fig. 16 is a plan view showing a second member of the force sensor apparatus.

Fig. 17 is a cross-sectional perspective view showing a second member of the force sensor apparatus.

Fig. 18 is an enlarged plan view showing the ring, the arm, and the second contact portion of the second member of the force sensor apparatus.

Fig. 19 is a cross-sectional perspective view of a sensor chip mounting portion and an arm of the force sensor device.

Fig. 20 is a top view of a second beam showing a second component of the force sensor assembly.

Fig. 21 is a cross-sectional view showing a tube portion, a flange, and a first fixing portion provided in a first member of the force sensor device.

Fig. 22 is a perspective view showing a second fixing portion on the first fixing portion.

Fig. 23 is a perspective view showing a flange provided to a first member of the force sensor apparatus.

Fig. 24 is an enlarged plan view showing the first contact portion and the second contact portion of the force sensor device.

Fig. 25 is a cross-sectional view showing a sensor chip mounting portion of the force sensor device, and is a view showing a cross-section along the Y-axis and the Z-axis.

Fig. 26 is a cross-sectional view showing a sensor chip mounting portion of the force sensor device, and is a view showing a cross-section along the W-axis and the Z-axis.

Fig. 27 is a diagram showing an analysis result in the case where the flange of the first member of the force sensor apparatus is attached to the component to be connected.

Fig. 28 is a diagram showing the analysis result in the case where the connecting object component is attached to the force receiving portion of the force sensor apparatus.

Fig. 29 is a perspective view showing a cross section of the force sensor apparatus of comparative example 1, and is a view showing a cut surface intersecting the X-axis and the Y-axis.

Fig. 30 is a graph showing the result of comparative verification 1 performed on the force sensor apparatus of comparative example 1.

Fig. 31 is a graph showing the result of effect verification 3 performed on the force sensor apparatus of example 1.

Fig. 32 is a graph showing the result of effect verification 4 performed on the force sensor apparatus of example 1.

Fig. 33 is a stress contour diagram showing the result of effect verification 5 on the force sensor apparatus of example 1.

Fig. 34 is a stress contour diagram showing the result of effect verification 6 on the force sensor apparatus of example 1.

In the figure:

1-force sensor means; 2-a mechanical arm; 4-arm body; 5-fitting; 20-strain variants; 20B-strain variant; 110-a sensor chip; 200—a first component; 212-a first contact; 214-a first contact; 216—a first contact; 220—a sensor chip mounting section; 222—bottom; 224-a barrel portion; 240—a force receiving portion; 242-annular grooves; 300-a tube (first connection portion); 332-flange; 332a—an abutment surface; 334-flange; 334 a-abutment surface; c1—corner (opposite in X-axis direction); c2—corner (opposite in Y-axis direction); 400-a second component; 412-a plurality of second contacts; 414-a plurality of second contacts.

Detailed Description

Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and overlapping description may be omitted.

(mechanical arm)

First, a robot arm 2 including a force sensor device 1 according to an embodiment will be described with reference to fig. 1 and 2. Fig. 1 is a side view showing a robot arm to which a force sensor device according to an embodiment is attached. Fig. 2 is a cross-sectional view showing a fitting and a force sensor device attached to the distal end portion of the arm body.

The robot arm 2 is, for example, an industrial robot arm. The industrial robot arm may be an arm of a robot such as a machine tool. The robot arm 2 includes a plurality of arm bodies 3 and 4. The plurality of arm bodies 3, 4 are connected via joints, respectively. The plurality of arm bodies 3, 4 are swingable about the rotation axis of the joint. The joint has an actuator for rotating the rotation shaft. The arm bodies 3, 4 are rotatable about axes extending in the longitudinal direction thereof.

The force sensor device 1 is attached to the distal end portion of the arm body 4 via a fitting 5. The fitting 5 is, for example, disc-shaped and has a predetermined thickness. The fitting 5 is formed with a screw hole for attaching the fitting 5 to the arm body 4. Further, the fitting 5 is provided with an internal thread 5a for attaching the force sensor device 1. The force sensor device 1 can be attached to the fitting 5 using a plurality of bolts 6.

(shaft, axial force and moment about the shaft)

Next, with reference to fig. 3, the axial and axial forces and the moment about the shaft will be described. Fig. 3 is a diagram showing the orientations of the X-axis, the Y-axis, the Z-axis, the force Fx along the X-axis, the force Fy along the Y-axis, the force Fz along the Z-axis, the moment Mx about the X-axis, the moment My about the Y-axis, and the moment Mz about the Z-axis. As shown in fig. 3, the X-axis direction, the Y-axis direction, and the Z-axis direction intersect with each other.

The force sensor device 1 can detect the force Fx in the X-axis direction, the force Fy in the Y-axis direction, and the force Fz in the Z-axis direction. The moment about each axis can detect a moment Mx rotating about the X axis, a moment My rotating about the Y axis, and a moment Mz rotating about the Z axis. The force Fx in the X-axis direction is an example of displacement in the X-axis direction. The Y-axis force Fy is an example of the Y-axis displacement. The Z-axis force Fz is an example of displacement in the Z-axis direction.

In each of the drawings, the X-axis direction, the Y-axis direction, and the Z-axis direction are sometimes illustrated by arrows. The X-axis direction, the Y-axis direction, and the Z-axis direction are based on the force sensor device 1. For example, in the robot arm 2 shown in fig. 1, when the robot arm 2 is displaced and the orientation of the force sensor device 1 is changed, the orientations of the X-axis direction, the Y-axis direction, and the Z-axis direction also change according to the orientation of the force sensor device 1.

(outline structure of force sensor device)

Next, a schematic configuration of the force sensor apparatus 1 will be described with reference to fig. 2 and 4 to 8. Fig. 4 is a perspective view showing the force sensor apparatus from above. Fig. 5 is a plan view showing the force sensor apparatus. Fig. 6 is a perspective view showing a cross section of the force sensor device, and is a view showing a cut surface intersecting the X-axis and the Y-axis. Fig. 7 is a perspective view showing a cross section of the force sensor apparatus, and is a view showing a cross section along the Y-axis and the Z-axis. Fig. 8 is a cross-sectional view showing the force sensor apparatus, and is a view showing a cross-section along the Y-axis and the Z-axis. The force sense sensor device 1 includes a sensor chip 110 and a strain body 20.

The sensor chip 110 functions as a six-axis displacement sensor. The sensor chip 110 may be, for example, a MEMS. The sensor chip 110 may detect displacement in at least one of the plurality of axial directions. The displacement in the axial direction may be, for example, a displacement in the X-axis direction, a displacement in the Y-axis direction, or a displacement in the Z-axis direction. The axial displacement may be, for example, a displacement about the X axis, a displacement about the Y axis, or a displacement about the Z axis.

The strain body 20 includes a first member 200, a second member 400, and a top plate 21. The strain body 20 is a two-piece strain body 20. The second member 400 is housed in the first member 200. A sensor chip mounting portion 220 to which the sensor chip 110 is mounted is formed inside the strain body 20. The top plate 21 is disposed so as to cover the sensor chip mounting portion 220. The top plate 21 is disposed at a position close to the fitting 5 in the Z-axis direction. Fig. 4 to 8 show a state in which the top plate 21 is detached.

(outline structure of first component)

Next, a schematic structure of the first member 200 will be described. Fig. 9 is a cross-sectional perspective view showing a first component of the force sensor apparatus. Fig. 10 is a plan view showing a first component of the force sensor apparatus. Fig. 11 is a perspective view showing the force sensor apparatus from below. The first member 200 includes a force receiving portion 240, a sensor chip mounting portion 220, a plurality of first beams 252 and 254, a plurality of first fixing portions 262 and 264, and a cylindrical portion 300.

(force receiving part)

As shown in fig. 2, 6 to 9, and 11, the force receiving portion 240 has a disk shape, for example. The thickness direction of the force receiving portion 240 is along the Z-axis direction. The outer diameter of the force receiving portion 240 is larger than that of the sensor chip mounting portion 220, for example. The force receiving portion 240 can be provided with an end effector of a robot arm. The force receiving portion 240 is provided with a bolt hole penetrating in the thickness direction.

(sensor chip mounting part)

Fig. 12 is an enlarged plan view of the sensor chip mounting portion showing the first member of the force sensor device. Fig. 13 is a perspective view showing a sensor chip mounting portion of a first member of the force sensor device. As shown in fig. 9, 12 and 13, the sensor chip mounting portion 220 has a bottom portion 222 and a cylindrical portion 224. The bottom 222 is mounted with respect to the force receiving portion 240. The bottom portion 222 is disposed at a position closer to the force receiving portion 240 in the Z-axis direction, and the cylindrical portion 224 is disposed at a position farther from the force receiving portion 240 than the bottom portion 222. The bottom 222 is, for example, plate-shaped. The plate thickness direction of the bottom portion 222 is along the Z-axis direction. The outer diameter of the force receiving portion 240 is larger than the outer diameter of the bottom portion 222. The bottom 222 is attached to a surface of the force receiving portion 240 opposite to the surface to which the end effector is attached in the Z-axis direction. A plurality of first contact portions 212, 214, 216 that contact the sensor chip 110 are provided at the bottom portion 222.

The plurality of first contact portions 212, 214, 216 protrude in the Z-axis direction to the opposite side from the force receiving portion 240. The plurality of first contact portions 212 include a first contact portion 212 disposed at the center of the bottom portion 222 as viewed in the Z-axis direction (in plan view), and a plurality of first contact portions 214, 216 disposed around the first contact portion 212. In addition, in the present specification, the term "radial" is sometimes used. For example, when the bottom 222 is viewed in the Z-axis direction, the radial direction is a direction along the radial direction of an imaginary circle centered on the first contact portion 212. The radial direction includes an X-axis direction and a Y-axis direction. In the case of viewing the bottom portion 222 in the Z-axis direction, the radial direction includes a direction away from the first contact portion 212.

The cylindrical portion 224 protrudes from the bottom portion 222 to the opposite side from the force receiving portion 240 in the Z-axis direction. The plurality of first contact portions 212, 214, 216 are arranged radially inside the cylindrical portion 224. The cylindrical portion 224 is formed so as to surround the plurality of first contact portions 212, 214, 216 when viewed in the Z-axis direction. The space enclosed by the barrel 224 and the bottom 222 forms a recess. The sensor chip 110 is disposed in a recess formed by the barrel 224 and the bottom 222.

(first beam)

Next, the first beams 252 and 254 will be described with reference to fig. 9, 10, and 14. Fig. 14 is a top view of the first beam showing the first component of the force sensing sensor assembly. In fig. 14, a first beam 254 is illustrated. The first beam 252 is only located differently from the first beam 254 and is the same shape. The plurality of first beams 252, 254 are formed to protrude radially outward of the sensor chip mounting portion 220. The plurality of first beams 252 are arranged to face each other in the radial direction. The plurality of first beams 254 are arranged to face each other in the radial direction. When viewed in the Z-axis direction, the directions in which the plurality of first beams 252 face each other and the directions in which the plurality of first beams 254 face each other are mutually different directions.

The first beams 252 and 254 are formed in a T shape when viewed in the Z-axis direction. The first beam 252 has a first portion 252a extending radially outward from the tubular portion 224 and a second portion 252b intersecting the first portion 252 a. The first beam 254 has a first portion 254a extending radially outward from the tubular portion 224 and a second portion 254b intersecting the first portion 254 a. The first beams 252 and 254 are not limited to the T-shape, and may be formed in a Y-shape, for example, or may be formed in other shapes.

(first fixing portion)

Next, the first fixing portions 262 and 264 will be described with reference to fig. 7 to 10. The plurality of first fixing portions 262 and 264 are arranged at positions corresponding to all the corners C1 and C2 of the virtual quadrangle, as viewed in the Z-axis direction. The plurality of first fixing portions 262, 264 are portions to which the second member 400 is fixed. The virtual quadrangle may be, for example, a quadrangle along the outer shape of the tube 300. The plurality of corner portions C1 are arranged so as to face each other in the X-axis direction, for example. The plurality of corner portions C2 are arranged so as to face each other in the Y-axis direction, for example. The plurality of first fixing portions 262 are disposed to face each other in the X-axis direction. The plurality of first fixing portions 264 are disposed to face each other in the Y-axis direction.

The plurality of first fixing portions 262 and 264 may be positioned at the position where the displacement is minimum in the force sensor device 1. The plurality of first fixing portions 262 and 264 are coupled to the plurality of first beams 252 and 254 and the cylinder 300. For example, the plurality of first fixing portions 262 and 264 have higher rigidity and are relatively less likely to deform than the plurality of first beams 252 and 254 and the tube 300 coupled to the first fixing portions 262 and 264. The first fixing portions 262 and 264 are disposed at positions corresponding to the corner portions C1 and C2 of the tube 300, and thus the relative positions are hardly changed.

As shown in fig. 10, the first fixing portions 262, 264 include fixing surfaces 262a, 264a. The fixing surfaces 262a, 264a include surfaces intersecting the Z-axis direction. The fixing surfaces 262a, 264a have, for example, a trapezoidal shape when viewed in the Z-axis direction.

The thickness of the first fixing portions 262, 264 in the Z-axis direction is thicker than the thickness of the first beams 252, 254 in the Z-axis direction. The fixing surface 262a is disposed at a position farther from the force receiving portion 240 than the first beams 252 and 254 in the Z-axis direction. The first fixing portions 262, 264 protrude further to the opposite side of the force receiving portion 240 than the first beams 252, 254 in the Z-axis direction.

The cylindrical portion 300 protrudes further to the opposite side of the force receiving portion 240 than the first fixing portions 262, 264 in the Z-axis direction. The cylindrical portion 300 is formed so as to surround the plurality of first fixing portions 262, 264, the plurality of first beams 252, 254, and the sensor chip mounting portion 220, as viewed in the Z-axis direction. The cylindrical portion 300 is formed continuously over the entire circumference in the Z-axis direction (in plan view).

(cylindrical portion of first Member)

Next, the cylinder 300 of the first member will be described with reference to fig. 4 to 11 and 15. Fig. 15 is a cross-sectional view showing a cylindrical portion of a first member of the force sensor device. Fig. 15 is a cross-sectional view of the tubular portion taken along X-Y from below. The barrel 300 has a plurality of outer walls 302, 304 and a plurality of inner walls 312, 314, 316, 318. The plurality of outer walls 302, 304 include radially outer faces. The plurality of inner walls 312, 314, 316, 318 include radially inner faces. The plurality of inner walls 312, 314, 316, 318 are radially disposed inward of the plurality of outer walls 302, 304.

The outer walls 302 and 304 are arranged in a quadrilateral shape having a plurality of corners C1 and C2 as vertices when viewed in the Z-axis direction. The plurality of outer walls 302, 304 include faces that intersect radially. The plurality of outer walls 302 are arranged so as to face the first beam 252 when viewed in the Z-axis direction. As shown in fig. 10, the outer wall 302 is disposed in such a manner as to intersect the first portion 252a of the first beam 252. The outer wall 304 is disposed in a manner intersecting the first portion 254a of the first beam 254.

The inner walls 312, 314, 316, 318 are arranged in an octagonal shape when viewed in the Z-axis direction. The plurality of inner walls 312 include YZ planes intersecting the X-axis direction. The plurality of inner walls 312 are opposed to each other in the X-axis direction. The plurality of inner walls 314 includes XZ faces intersecting the Y-axis direction. The plurality of inner walls 314 are opposed to each other in the Y-axis direction. The plurality of inner walls 316 includes a face opposite the outer wall 302. The plurality of inner walls 318 includes a face opposite the outer wall 304.

The fixing surface 262a is formed to protrude radially inward from the inner wall 312 as viewed in the Z-axis direction. The fixing surface 264a is formed to protrude radially inward from the inner wall 314 as viewed in the Z-axis direction. The first fixing portion 262 includes a portion protruding radially inward from the inner wall 312. The first fixing portion 264 includes a portion protruding radially inward from the inner wall 314. The tube 300 includes a portion disposed between the plurality of first fixing portions 262 and 264 and connecting the plurality of first fixing portions 262 and 264.

The length of the cylindrical portion 300 extending from the plurality of first fixing portions 262, 264 in the Z-axis direction may be longer than the thickness of the plurality of first fixing portions 262, 264 in the Z-axis direction. The cylindrical portion 300 has a predetermined length in the Z-axis direction.

(groove of first component)

As shown in fig. 10 and 11, a plurality of grooves 282 and 284 are formed in the first member 200. The plurality of slots 282, 284 extend through the first member 200 in the Z-axis direction. A plurality of slots 282 are formed between the first beam 252 and the inner wall 316, as viewed in the Z-axis direction. The plurality of slots 282 extend along the length of the second portion 252b of the first beam 252. A plurality of slots 284 are formed between the first beam 254 and the inner wall 318, as viewed in the Z-axis direction. A plurality of slots 284 extend along the length of the second portion 254b of the first beam 254. The plurality of grooves 282, 284 may be formed so as not to penetrate in the Z-axis direction.

(outline structure of the second component)

Next, a schematic structure of the second member 400 will be described. Fig. 16 is a plan view showing a second member of the force sensor apparatus. Fig. 17 is a cross-sectional perspective view showing a second member of the force sensor apparatus. Fig. 18 is an enlarged plan view showing the ring, the arm, and the second contact portion of the second member of the force sensor apparatus. Fig. 19 is a cross-sectional perspective view of a sensor chip mounting portion and an arm of the force sensor device. The second member 400 includes a plurality of second contact portions 412, 414, a support portion 420, a plurality of second beams 432, 434, and a plurality of second fixing portions 442, 444.

(second contact portion and supporting portion)

The support portion 420 supports the plurality of second contact portions 412, 414. The plurality of second contact portions 412 are separated in the X-axis direction. The plurality of second contact portions 414 are separated in the Y-axis direction. Support 420 has a ring 422 and a plurality of arms 462, 464. The ring 422 is formed along a circumference centered on the Z axis. The ring 422 has a plate shape. The plate thickness direction of the ring 422 is along the Z-axis direction.

(arm of the second part)

The plurality of arms 462 are opposed in the X-axis direction. The plurality of arms 462 have a first portion 462a and a second portion 462b. The first portion 462a extends in the Z-axis direction from the ring 422 toward the bottom 222 of the first component 200. The second portion 462b is separated from the ring 422 in the Z-axis direction. The second portion 462b is bent from an end of the first portion 462a in the Z-axis direction and extends in the X-axis direction. The plurality of second portions 462b are formed to be adjacent to each other in the X-axis direction.

The plurality of arms 464 are opposed in the X-axis direction. The plurality of arms 464 have a first portion 464a and a second portion 464b. The first portion 464a extends in the Z-axis direction from the ring 424 toward the bottom 222 of the first component 200. The second portion 464b is separated from the ring 422 in the Z-axis direction. The second portion 464b is bent from an end of the first portion 464a in the Z-axis direction and extends in the Y-axis direction. The plurality of second portions 464b are formed so as to approach each other in the Y-axis direction.

The distal ends of the arms 462, 464 are coupled to each other. The front end of the arm 462 is a portion of the second portion 462b that is distal from the first portion 462 a. The front end of the arm 464 is a portion of the second portion 464b that is distal from the first portion 464 a.

The plurality of second portions 462b, 464b intersect and join each other at a radial center. A hole 468 penetrating in the Z-axis direction is formed at a portion where the plurality of second portions 462b, 464b intersect. The first contact 212 is inserted through the aperture 468. The aperture 468 and the first contact 212 are disposed at the center of the plurality of second contacts 412, 414. The plurality of second contact portions 412 protrude from the second portion 462b in the Z-axis direction. The plurality of second contact portions 414 protrude from the second portion 464b in the Z-axis direction.

(second beam)

Next, the second beams 432 and 434 will be described with reference to fig. 16, 17, and 20. Fig. 20 is a top view of a second beam showing a second component of the force sensor assembly. In fig. 20, a second beam 434 is illustrated. The second beam 432 is only located differently from the second beam 434 and is the same shape. A plurality of second beams 432, 434 are formed to protrude radially outward of the ring 422. The plurality of second beams 432 are arranged to face each other in the radial direction. The plurality of second beams 434 are arranged to be opposed to each other in the radial direction. When viewed in the Z-axis direction, the directions in which the plurality of second beams 432 face the plurality of second beams 434 are different from each other.

The second beams 432, 434 are formed in a T shape as viewed in the Z-axis direction. The second beam 432 has a first portion 432a extending radially outward from the ring 422 and a second portion 432b intersecting the first portion 432 a. The second beam 434 has a first portion 434a protruding radially outward from the ring 424 and a second portion 434b intersecting the first portion 434 a. The second beams 432 and 434 are not limited to the T-shape, and may be formed in a Y-shape, for example, or may be formed in other shapes.

(second fixing portion)

The plurality of second fixing portions 442 and 444 shown in fig. 16, 17, and 20 are portions fixed to the plurality of first fixing portions 262 and 264. The plurality of second fixing portions 442 are disposed outside the ring 422 and face each other in the X-axis direction. The plurality of second fixing portions 444 are disposed outside the ring 422 and face each other in the Y-axis direction.

(fixation of the second fixing portion with respect to the first fixing portion)

Fig. 21 is a cross-sectional view showing a tube portion, a flange, and a first fixing portion provided in a first member of the force sensor device. Fig. 22 is a perspective view showing a second fixing portion on the first fixing portion. As shown in fig. 7, 8, 21 and 22, the plurality of second fixing portions 442, 444 are fixed to the plurality of first fixing portions 262, 264. Specifically, the second fixing portion 442 is disposed on the first fixing portion 262 and fixed to the first fixing portion 262. The second fixing portion 444 is disposed on the first fixing portion 264 and fixed to the first fixing portion 264. The second fixing portions 442 and 444 are disposed opposite to the force receiving portion 240 with respect to the first fixing portions 262 and 264 in the Z-axis direction. The second fixing portions 442, 444 are engaged with the first fixing portions 262, 264, for example, by welding.

(flange of first part)

Next, the flanges 332 and 334 provided in the first member 200 will be described with reference to fig. 2, 4 to 11, 21, and 23. The flanges 332, 334 extend radially outward from the barrel 300 as viewed in the Z-axis direction. The flanges 332, 334 have a predetermined thickness in the Z-axis direction. The flange 332 has a bolt hole 336 formed therethrough in the Z-axis direction. The plurality of bolt holes 336 are provided at positions corresponding to the corners C1, C2 of the virtual quadrangle.

The flanges 332, 334 have abutment surfaces 332a, 334a that protrude in the Z-axis direction on the opposite side of the end surface 300a of the tube 300 from the force receiving portion 240. The abutment surfaces 332a, 334a are formed on the surfaces of the flanges 332, 334 on the opposite side from the force receiving portion 240. The contact surfaces 332a and 334a are surfaces that can contact the fitting 5 shown in fig. 2. The abutment surfaces 332a, 334a protrude in the Z-axis direction opposite to the force receiving portion 240 from the end surface 300a of the tube portion 300, and therefore the end surface 300a is formed so as not to contact the fitting 5. The end surface 300a may include a surface that contacts the fitting 5. The steps of the abutment surfaces 332a, 334a with respect to the end surface 300a in the Z-axis direction may be, for example, 0.2mm.

The abutment surfaces 332a, 334a are formed around the bolt hole 336 as viewed in the Z-axis direction. For example, the contact surfaces 332a, 334a are provided over the entire circumference so as to surround the bolt hole 336. The surfaces of the flanges 332 and 334 on the opposite sides of the force receiving portion 240 may include surfaces that do not protrude from the end surface 300 a.

(annular groove of force receiving portion)

Next, with reference to fig. 2, 6, 8, and 11, an annular groove 242 provided on the bottom surface 240a of the force receiving portion 240 will be described. An annular groove 242 is formed in the bottom surface 240a of the force receiving portion 240. The bottom surface 240a of the force receiving portion 240 is a surface on the opposite side of the sensor chip mounting portion 220 in the Z-axis direction. The annular groove 242 is formed in a circumferential shape centering on the Z axis passing through the center of the force receiving portion 240.

As shown in fig. 6 and 8, for example, the annular groove 242 may have an outer diameter larger than the outer diameter of the tube 224 of the sensor chip mounting portion 220. The force receiving portion 240 has a plurality of bolt holes 244 penetrating in the Z-axis direction. The annular groove 242 is formed radially inward of the plurality of bolt holes 244. The depth of the annular groove 242 in the Z-axis direction may be 20% to 25% of the thickness of the force receiving portion 240, for example. The opening width of the annular groove 242 intersecting the circumferential direction may be the same as the depth of the groove 242, for example. The annular groove 242 is formed around the entire circumference around the Z axis. The annular groove 242 is not limited to a groove continuous over the entire circumference in the circumferential direction, and may be formed locally.

(sensor chip, first contact portion, and second contact portion)

Next, the arrangement of the first contact portions 212, 214, 216 and the second contact portions 412, 414 with respect to the sensor chip 110 will be described with reference to fig. 12, 13, 18 and 24 to 26. Fig. 24 is an enlarged plan view showing the first contact portion and the second contact portion of the force sensor device. Fig. 25 is a cross-sectional view showing a sensor chip mounting portion of the force sensor device, and is a view showing a cross-section along the Y-axis and the Z-axis. Fig. 26 is a cross-sectional view showing a sensor chip mounting portion of the force sensor device, and is a view showing a cross-section along the W-axis and the Z-axis. Fig. 24 shows the V-axis and the W-axis intersecting each other when viewed in the Z-axis direction. The V axis passes through a position where the X axis is tilted 45 degrees about the Z axis, and the W axis passes through a position where the Y axis is tilted 45 degrees about the Z axis.

As described above, the plurality of first contact portions 212, 214, 216 are formed at the bottom 222 of the first member 200. A plurality of first contact portions 214, 216 are arranged on diagonal lines along the X-axis and the Y-axis as viewed in the Z-axis direction, and a first contact portion 212 is arranged at the center of these first contact portions 214, 216. Fig. 12 and 13 show the sensor chip mounting portion 220 before the plurality of second contact portions 412, 414 of the second member 400 are arranged.

As described above, the plurality of second contact portions 412, 414 shown in fig. 18 are supported by the plurality of arms 462, 464. As shown in fig. 24, in a state where the second member 400 is fixed to the first member 200, the plurality of second contact portions 412, 414 are arranged between the plurality of first contact portions 214, 216. The second contact portion 412 is disposed between the first contact portions 214, 216 in the Y-axis direction. The second contact portions 412 are disposed on both sides of the first contact portion 212 in the center in the X-axis direction. The second contact portion 414 is disposed between the first contact portions 214, 216 in the X-axis direction. The second contact portions 414 are disposed on both sides of the first contact portion 212 in the center in the Y-axis direction.

As shown in fig. 25 and 26, the plurality of first contact portions 212, 214, 216 and the plurality of second contact portions 412, 414 are in contact with the bottom surface 110a of the sensor chip 110 at predetermined intervals in the X-axis direction and the Y-axis direction.

The plurality of second contacts 412, 414 of the second component 400 can be regarded as fixed points that are not displaced relative to the sensor chip 110. The plurality of first contact portions 212, 214, 216 of the first member 200 can be regarded as input points of relative displacement with respect to the sensor chip 110.

In the force sense sensor device 1, when the force receiving portion 240 receives force, the force is transmitted from the force receiving portion 240 to the bottom portion 222 of the sensor chip mounting portion 220. The bottom 222 is slightly deformed by being forced from the force receiving portion 240. The displacement of the plurality of first contact portions 212, 214, 216 is different depending on the direction and magnitude of the force. The sensor chip 110 can detect the force Fx in the X-axis direction, the force Fy in the Y-axis direction, the force Fz in the Z-axis direction, the moment Mx about the X-axis, the moment My about the Y-axis, and the moment Mz about the Z-axis by detecting the displacement of the plurality of first contact portions 212, 214, 216 relative to the second contact portions 412, 414.

(subject of the prior art)

Next, the problems of the prior art will be described. The force sensor device is attached to the industrial robot as a connection target directly by screw fastening or indirectly via an adapter. It is difficult to make the mounting surface of the force sensor device and the mounting surface on the opposite side completely flat, and a gap is generated between the two mounting surfaces. Therefore, the tightening force of the screw causes deformation such that the gap is eliminated in the force sensor device and the counterpart member. In such a case, the strain body of the force sensor apparatus is strained, thereby generating a mounting offset. In other words, the zero point output changes.

If the mounting offset occurs, there is a problem that the dynamic range applicable to the force sensor device becomes small. In addition, if the mounting misalignment occurs, there is a problem that the reproducibility of the zero point is deteriorated when the use is repeated. Further, the temperature change of the force sensor device and/or the robot arm causes a problem that the output change becomes large and the temperature characteristic of the zero point output becomes large. For example, when a screw thread for mounting the force sensor apparatus is loosened, the axial force of the screw thread changes, whereby the influence of the mounting offset becomes large.

(action effect of force sensor device 1)

In the force sensor device 1 according to the present embodiment, the first member 200 includes the cylindrical portion 300 extending in the Z-axis direction on the opposite side to the force receiving portion 240, and therefore, deformation caused by the gap between the mounting surface of the force sensor device 1 and the mounting surface on the opposite side can be absorbed by deformation of the cylindrical portion 300. Therefore, in the force sensor device 1, compared with a structure not including the tube 300, deformation transmitted to the plurality of first fixing portions 262 and 264, the plurality of first beams 252 and 254, and the sensor chip mounting portion 220 can be suppressed. In the force sensor device 1, the deformation of the mounting surface is difficult to be transmitted to the first contact portions 212, 214, 216.

The force sensor device 1 includes flanges 332 and 334 extending radially outward from the tubular portion 300, and bolt holes 336 are formed in the flanges 332 and 334, so that the force generated when fastening the bolts is less likely to be transmitted to the sensor chip mounting portion 220. Since the tube 300 can flex radially inward or radially outward, the force (displacement input) transmitted to the sensor chip mounting portion 220 via the tube 300 can be reduced when the screw position is present on the outside of the tube 300, as compared with when the screw position is present on the inside of the tube 300. By the deformation of the tube 300, the force (displacement) input to the sensor chip 110 is absorbed.

In the force sensor device 1, since the flanges 332 and 334 have the contact surfaces 332a and 334a protruding in the Z-axis direction from the end surface 300a of the tube 300, the area in contact with the other side can be limited to the contact surfaces 332a and 334a. The region in contact with the counterpart side is limited to the contact surfaces 332a, 334a of the flanges 332, 334 radially outside the tube 300. For example, in the case of performing stress analysis, the region in contact with the opposite side can be restricted, and therefore the analysis accuracy can be improved. In addition, when the force sensor device 1 is connected to the other side, the influence of the surface roughness of the other side region facing the end surface 300a of the cylinder 300 can be avoided.

In the force sensor device 1, since the annular groove 242 is formed in the bottom surface 240a of the force receiving portion 240, the force when the end effector to be connected is attached to the force receiving portion 240 can be reduced. Since the annular groove 242 is formed radially inward of the plurality of bolt holes 244, it is difficult for the force receiving portion 240 to deform, thereby making it difficult for the force to be transmitted to the sensor chip mounting portion 220.

In the force sensor device 1, since the annular groove 242 has an outer diameter larger than that of the sensor chip mounting portion 220, the force receiving portion 240 can be deformed outside the sensor chip mounting portion 220 in the radial direction. This makes it difficult for the force generated when the connection object is connected to the force receiving portion 240 to be transmitted to the sensor chip mounting portion 220.

In the force sensor device 1, the tube 300 is formed continuously over the entire circumference as viewed in the Z-axis direction, and therefore, the force transmitted to the tube 300 can be dispersed over the entire circumference of the tube.

In the force sensor device 1, the inner walls 312, 314, 316, 318 of the tube 300 are arranged in an octagonal shape when viewed in the Z-axis direction. By disposing the inner walls 312, 314, 316, 318 in this manner, the rigidity of the tube 300 can be improved, for example, as compared with a case where the inner walls are formed in a circular shape. This reduces the force transmitted to the sensor chip mounting portion 220 via the tube 300.

In the force sensor device 1, the inner walls 312, 314, 316, 318 of the tube 300 are arranged in an octagonal shape when viewed in the Z-axis direction. By disposing the inner walls 312, 314, 316, 318 in this manner, the rigidity of the tube 300 can be improved by a smaller outer diameter dimension than in the case where the inner walls are formed in a circular shape, for example.

In the force sensor device 1, the first beams 252 and 254 and the first fixing portions 262 and 264 are arranged in an octagonal shape, and accordingly, the outer shape of the second member 400 is also octagonal. In the force sensor device 1, the first beams 252, 254, the first fixing portions 262, 264, the outer shape of the second member 400, and the inner walls 312, 314, 316, 318 of the tube 300 are octagonal. By aligning the inner portion of the tubular portion 300 in the octagonal shape and providing the flanges 332 and 334 with the corners of the quadrangle in this way, the required rigidity can be obtained, the external shape of the force sensor device 1 can be reduced, and the weight of the force sensor device 1 can be reduced.

The tube 300 has a certain rigidity, and in the Z-axis direction, the rigidity is different between a portion closer to the force receiving portion 240 than the surface on which the second member 400 is provided and portions closer to the flanges 332 and 334. In the tubular portion 300, the rigidity of the portions near the flanges 332 and 334 is lower than the rigidity of the portions near the force receiving portion 240, and thus the portions near the flanges 332 and 334 are not deflected when the force sensor device 1 is mounted on the component to be connected.

The inner walls 312, 314, 316, 318 of the tube 300 are arranged in an octagonal shape when viewed in the Z-axis direction, but the shape of the inner walls is not limited to an octagonal shape, and may be, for example, a circular shape, a quadrangular shape, or other shapes.

In the force sensor device 1, the outer walls 302 and 304 of the tube 300 constituting the outer shape of the first member 200 are formed to constitute a part of a quadrangle when viewed from the Z-axis direction, and the flanges 332 and 334 are provided at positions corresponding to the corners C1 and C2 of the quadrangle. This ensures the rigidity of the tube 300. For example, the rigidity of the tube 300 can be improved as compared with a case where the outer wall is formed in a circular shape. This reduces the force transmitted to the sensor chip mounting portion 220 via the tube 300.

In the force sensor device 1, the outer walls 302 and 304 of the tube 300 constituting the outer shape of the first member 200 are formed to constitute a part of a quadrangle when viewed from the Z-axis direction, and the flanges 332 and 334 are provided at positions corresponding to the corners C1 and C2 of the quadrangle. This ensures the rigidity of the tube 300. For example, the rigidity of the tube 300 can be improved with a smaller outer diameter than in the case where the outer wall is formed in a circular shape.

In the force sensor device 1, the length of the cylindrical portion 300 of the portion extending from the plurality of first fixing portions 262, 264 may be longer than the length of the plurality of first fixing portions 262, 264 in the Z-axis direction. In this way, according to the force sensor device 1 including the cylindrical portion 300 having a predetermined length in the Z-axis direction, the force transmitted to the sensor chip mounting portion 220 via the cylindrical portion 300 can be reduced. As a result, the influence of the mounting misalignment can be reduced, and in the force sensor apparatus 1, the change in the zero point output can be suppressed.

(Effect verification 1)

Next, the result of the effect verification 1 will be described. Fig. 27 is a diagram showing an analysis result in the case where the flange of the first member of the force sensor apparatus is attached to the component to be connected. In the effect verification 1, a gap of 50 μm was formed by cutting the contact surface of the adapter of the component to be connected, and the deformation of the force sensor device 1 in the case where the force sensor device 1 was attached to the component to be connected was simulated. In the effect verification 1, a case where the flanges 332, 334 of the first member 200 of the force sensor apparatus 1 are attached to the connection object by screw fastening was simulated. Here, the fitting 5 or the arm body is assumed as a component to be connected. The result of the effect verification 1 is shown in fig. 27. Further, the flange surface of the first member 200 was cut to 50 μm to form a gap at one portion of the flange surface, and the effect verification 1 was performed.

As shown in fig. 27, deformation is confirmed in the flange 334 and the tube 300 surrounded by the two-dot chain line. Further, deformation was also confirmed in the first beams 252, 254 and the second beams 432, 434. However, no relative displacement difference occurs between the plurality of first contact portions 212, 214, 216 of the sensor chip mounting portion 220 surrounded by the broken line and the plurality of second contact portions 412, 414 supported by the arms 462, 464 of the second member 400. By deforming the flange 334 and the cylindrical portion 300, the force is absorbed, and no relative displacement difference is generated between the plurality of first contact portions 212, 214, 216 and the plurality of second contact portions 412, 414.

(Effect verification 2)

Next, the result of the effect verification 2 will be described. Fig. 28 is a diagram showing the analysis result in the case where the connecting object component is attached to the force receiving portion of the force sensor apparatus. In the effect verification 2, a gap of 50 μm was formed by cutting the contact surface of the connection target component, and the deformation of the force sensor device 1 was simulated when the connection target component was attached to the force receiving portion 240 of the force sensor device 1. In the effect verification 2, a case where the force receiving portion 240 of the force sensor apparatus 1 is attached to the connection object by screw fastening was simulated. Here, as the component to be connected, an end effector of a robot arm is assumed. The result of effect verification 2 is shown in fig. 28. Further, the flange surface of the first member was cut to 50 μm to form a gap at one portion of the flange surface, and the effect test 2 was performed.

As shown in fig. 28, deformation was confirmed in the outer peripheral portion of the force receiving portion 240 surrounded by the two-dot chain line. The outer peripheral portion of the force receiving portion 240 is a portion radially outside the annular groove 242. However, no relative displacement difference occurs between the plurality of first contact portions 212, 214, 216 of the sensor chip mounting portion 220 surrounded by the broken line and the plurality of second contact portions 412, 414 supported by the arms 462, 464 of the second member 400. By the deformation of the outer peripheral portion of the force receiving portion 240, the force is absorbed, and no relative displacement difference occurs between the plurality of first contact portions 212, 214, 216 and the plurality of second contact portions 412, 414.

Comparative example 1

Next, comparative example 1 will be described. Fig. 29 is a perspective view showing a cross section of the force sensor apparatus of comparative example 1, and is a view showing a cut surface intersecting the X-axis and the Y-axis. The force sensor apparatus 501 of comparative example 1 includes a base plate 502, a frame 503, and a ring 504. The base plate 502, the frame 503, and the ring 504 are circular when viewed in the Z-axis direction. The bottom plate 502, the frame 503, and the ring 504 are arranged so as to overlap when viewed in the Z-axis direction. Bolt holes through which bolts are inserted are formed in the bottom plate 502, the frame 503, and the ring 504. The frame 503 is provided with a plurality of first contact portions, and the ring 504 is provided with a plurality of second contact portions.

The frame 503 does not have a cylindrical portion extending in the Z-axis direction from the fixing portion to which the ring 504 is fixed. The frame 503 is not provided with a flange that can be attached to a component to be connected to the force sensor device 501. The force sensor apparatus 501 has a disk-shaped top plate covering the ring 504.

(comparative verification 1)

A comparative verification 1 was performed on such a force sensor apparatus 501 according to comparative example 1. Fig. 30 is a graph showing the result of comparative verification 1 performed on the force sensor apparatus of comparative example 1.

In comparative verification 1, a gap of 50 μm was formed using a gap gauge, and deformation of the force sensor device 501 in the case where the force sensor device 501 was attached to a part to be connected was simulated. In comparative verification 1, a case where the force sensor device 501 is attached to a component to be connected by screw tightening was simulated. Here, the fitting 5 or the arm body is assumed as a component to be connected. The result of comparative verification 1 is shown in fig. 30. In fig. 30, the analysis result based on simulation and the measurement result based on the real machine are shown.

In fig. 30, the vertical axis represents the mounting offset variation [%fs ]. The "mounting offset change" indicates a ratio of the magnitude of the change in zero point when the force sensor apparatus 501 is mounted on the component to be connected. When the offset change is 100% fs, the offset change is equal to a state in which a displacement corresponding to the sensor rating is input to the sensor chip mounting unit 220.

Here, a case where the shift change is positive and a case where the shift change is negative will be described with reference to fig. 25. The offset is generated by the relative positional relationship of the first contact portion 212 and the second contact portion 414. The positive and negative cases indicate movement in opposite directions to each other. When Fx is positive, the first contact portion 212 moves from the front side toward the back side of the paper surface in the X-axis direction with respect to the second contact portion 414. When Fx is negative, the first contact portion 212 is moved from the back side of the paper surface toward the front side in the X-axis direction with respect to the second contact portion 414. When Fy is positive, the first contact portion 212 is moved in the direction indicated by the arrow Y (+) along the Y axis direction with respect to the second contact portion 414. When Fy is negative, the first contact portion 212 is moved in the direction indicated by the arrow Y (-) along the Y-axis direction with respect to the second contact portion 414. When Fz is positive, the first contact portion 212 is moved relative to the second contact portion 414 in the direction indicated by the arrow Z (+) along the Z axis direction. When Fz is negative, the first contact portion 212 is moved in the direction indicated by the arrow Z (-) along the Z-axis direction with respect to the second contact portion 414.

Fig. 30 shows graphs GAx, GAy, and GAz as measurement results in the real machine, and shows graphs GBx, GBy, and GBz as analysis results based on simulation. Graphs GAx and GBx represent the maximum value of the absolute value of the offset change in the X-axis direction. Graphs GAy and GBx represent the maximum value of the absolute value of the shift change in the Y-axis direction. Graphs GAz and GBz represent the maximum value of the absolute value of the shift change in the Z-axis direction.

The measurement result using the real machine and the analysis result from the simulation both confirm that a large offset output is generated.

Example 1, effect verification 3

Next, the result of performing the effect verification 3 on the force sensor apparatus 1 of example 1 will be described. The force sensor device 1 of example 1 is the force sensor device 1 of the above embodiment. Fig. 31 is a graph showing the result of effect verification 3 performed on the force sensor apparatus of example 1.

In the effect verification 3, a gap of 50 μm was formed by cutting the contact surface of the connection target component, and the deformation of the force sensor device 1 in the case of attaching the force sensor device 1 to the connection target component was simulated. In the effect verification 3, a case where the flanges 332, 334 of the first member 200 of the force sensor apparatus 1 are attached to the connection object by screw fastening was simulated. Here, the fitting 5 or the arm body is assumed as a component to be connected. The result of the effect verification 3 is shown in fig. 31. Further, the flange surface of the first member 200 was cut to 50 μm to form a gap at one portion of the flange surface, and the effect verification 3 was performed.

As shown in fig. 31, the shift change is small in the X-axis direction, the Y-axis direction, and the Z-axis direction. The shift change was found to be very small.

Example 1, effect verification 4

Next, the result of performing the effect verification 4 on the force sensor apparatus 1 of example 1 will be described. Fig. 32 is a graph showing the result of effect verification 4 performed on the force sensor apparatus of example 1.

In the effect verification 4, a gap of 50 μm was formed by cutting the contact surface of the connection target component, and the deformation of the force sensor device 1 was simulated when the connection target component was attached to the force receiving portion 240 of the force sensor device 1. In the effect verification 4, a case where the force receiving portion 240 of the force sensor apparatus 1 is attached to the connection object by screw fastening was simulated. Here, as the component to be connected, an end effector of a robot arm is assumed. The result of the effect verification 4 is shown in fig. 32. Further, the flange surface of the force receiving portion 240 was cut to 50 μm to form a gap at one portion of the flange surface, and the effect verification 4 was performed.

As shown in fig. 32, in the X-axis direction, the Y-axis direction, and the Z-axis direction, the shift change is hardly detected. The shift change was found to be very small.

Example 1, effect verification 5

Next, the result of performing the effect verification 5 on the force sensor apparatus 1 of example 1 will be described. Fig. 33 is a stress contour diagram showing the result of effect verification 5 on the force sensor apparatus of example 1.

In the effect verification 5, the force sensor device 1 was attached to a component to be connected to the arm main body or the fitting, and the component to be connected to the end effector was attached to the force receiving portion 240 of the force sensor device 1, so that the stress at the time of heating the arm main body and the fitting was analyzed. Here, the arm body and the fitting were heated from an initial temperature of 22 ℃ to 45 ℃ and analyzed. Assuming that the robot arm heats up, the temperature of the arm main body is set to 45 ℃. The force sensor device 1 is made of stainless steel, and the connecting object is made of aluminum alloy. The result of the effect verification 5 is shown in fig. 33.

As shown in fig. 33, deformation is confirmed in the flange 334 and the tube 300 surrounded by the two-dot chain line. However, the relative displacement difference between the plurality of first contact portions 212, 214, 216 of the sensor chip mounting portion 220 surrounded by the broken line and the plurality of second contact portions 412, 414 supported by the arms 462, 464 of the second member 400 is very small. By the deformation of the outer peripheral portion of the force receiving portion 240, the force is absorbed, and the relative displacement difference between the plurality of first contact portions 212, 214, 216 and the second contact portions 412, 414 is very small. The change in the relative positional relationship of the plurality of first contact portions 212, 214, 216 and the second contact portions 412, 414 is very small with respect to the deformation of the outer peripheral portion of the force receiving portion 240.

Example 1, effect verification 6

Next, the result of performing the effect verification 6 on the force sensor apparatus 1 of example 1 will be described. Fig. 34 is a stress contour diagram showing the result of effect verification 6 on the force sensor apparatus of example 1.

In the effect verification 6, the force sensor device 1 was attached to a component to be connected to the arm main body or the fitting, and the component to be connected to the end effector was attached to the force receiving portion 240 of the force sensor device 1, so that the stress when the arm main body, the fitting, and the end effector were heated was analyzed. Here, the case where the arm main body, the fitting, and the end effector were heated from the initial temperature of 22 ℃ to 45 ℃ was analyzed. The heat generation of the robot and the rise of the outside air temperature were assumed, and the arm main body, the fitting, and the end effector were set to 45 ℃. The force sensor device 1 is made of stainless steel, and the connecting object is made of aluminum alloy. The result of the effect verification 6 is shown in fig. 34.

As shown in fig. 34, deformation is confirmed in the flange 334 and the tube 300 surrounded by the two-dot chain line. Deformation is confirmed in the outer peripheral portion of the force receiving portion 240 surrounded by the one-dot chain line. However, the relative displacement difference between the plurality of first contact portions 212, 214, 216 of the sensor chip mounting portion 220 surrounded by the broken line and the plurality of second contact portions 412, 414 supported by the arms 462, 464 of the second member 400 is very small. By deforming the flange 33 and the cylindrical portion 300, the force is absorbed, and the difference in relative displacement between the plurality of first contact portions 212, 214, 216 and the second contact portions 412, 414 is very small. The change in the relative positional relationship of the plurality of first contact portions 212, 214, 216 and the second contact portions 412, 414 is very small with respect to the deformation of the flange 334 and the outer peripheral portion of the force receiving portion 240.

The preferred embodiments have been described in detail above, but the present invention is not limited to the above embodiments, and various modifications and substitutions can be made to the above embodiments without departing from the scope of the claims.

Claims (9)

1. A force sensor device, comprising:

a sensor chip that detects displacement in at least one of a plurality of axial directions;

a first component having: a sensor chip mounting portion including a first contact portion that contacts the sensor chip and mounting the sensor chip; a force receiving portion connected to the sensor chip mounting portion; a first beam extending from the sensor chip mounting portion in a radial direction of an imaginary circle centered on the sensor chip mounting portion; a first fixing portion connected to the first beam; a tube portion connecting the first fixing portion; and a flange protruding from the cylindrical portion and formed with a bolt hole; and

a second component having: a second contact portion that contacts the sensor chip; a support portion that supports the second contact portion; a second beam extending from the support portion in the radial direction; and a second fixing portion connected to the second beam and fixed to the first fixing portion,

The flange includes an abutment surface that protrudes from an end surface of the barrel portion.

2. A force sensor apparatus according to claim 1, wherein,

an annular groove is formed in the surface of the force receiving portion.

3. A force sensor apparatus according to claim 2, wherein,

the annular groove has an outer diameter larger than an outer diameter of the sensor chip mounting portion.

4. A force sensor apparatus according to any of claims 1 to 3,

the cylindrical portion is formed continuously over the entire circumference in a plan view.

5. The force sensor apparatus of any of claims 1-4, wherein,

the inner wall of the cylindrical portion is formed in an octagonal shape in a plan view.

6. The force sensor apparatus of any of claims 1-5, wherein,

the first member is formed in a quadrangular shape in a plan view,

the flanges are provided at positions corresponding to all corners of the quadrangle.

7. The force sensor apparatus of any of claims 1-5, wherein,

the length of the tube portion extending from the first fixing portion is longer than the length of the first fixing portion.

8. A robot arm is characterized by comprising:

the force sensor device of any one of claims 1 to 7; and

an arm body connected to the force sensor device.

9. The mechanical arm of claim 8, wherein the mechanical arm comprises a plurality of arms,

and a fitting attached to the arm main body,

the force sensor device is mounted to the arm body via the fitting.