Industrial robot, control system, and method for controlling plurality of industrial robots

Abstract

An industrial robot, a control system, and a method for controlling a plurality of industrial robots. The industrial robot includes a work mechanism and a drive device. The working mechanism has a tool disposed on the tip side of the arm. The driving device drives the working mechanism. The drive device includes a motor, a wave generator, an externally toothed gear, and an internally toothed gear. The wave generator has a non-perfect circular cross-section perpendicular to the central axis, and is rotatable about the central axis together with the rotating part of the motor. At least a portion of the external gear is disposed radially outward of the wave generator, and the external gear has a plurality of external teeth protruding radially outward. At least a portion of the internally toothed gear is disposed radially outward of the externally toothed gear, and the internally toothed gear expands annularly about the central axis, and has a plurality of internally toothed teeth protruding radially inward and partially meshing with the plurality of externally toothed teeth. The tool can rotate together with an output part which is either the external gear or the internal gear. At least one of the external gear and the internal gear is provided with a plurality of strain gauges.

Description

Technical Field

[0001] The present invention relates to an industrial robot, a control system of the industrial robot, and a control method for a plurality of industrial robots. Background Art

[0002] In recent years, it is known that there is a device in which a mechanism for tightening screws as an end effector is installed at the front end of the arm of an industrial robot (for example, Patent Document 1). In the screw tightening device of Patent Document 1, a cutter head is installed at the front end of the device, and the cutter head is used to rotate the screw while engaging with the screw and installing it on the workpiece. In addition, a motor is used as a driving source, and a force sensor for detecting the reaction force from the screw, that is, the force pressing the cutter head, is arranged between the flange that supports the cutter head and rotates and the cutter head. In addition, a motor and a torque sensor for detecting the torque generated around the rotation axis are arranged inside the wrist including the flange. In addition, the control device controls the robot based on the force information detected by the force sensor and the torque sensor.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-127908

[0004] However, in the screw fastening device of Patent Document 1, it is necessary to configure the sensor separately from the driving source of the industrial robot, so it is difficult to achieve miniaturization of the entire industrial robot. This is not limited to the screw fastening device, but also applies to industrial robots having a tool that rotates relative to a workpiece. Summary of the invention

[0005] An object of the present invention is to provide a technology that can detect torque acting between a tool and a workpiece in an industrial robot and can reduce the size of the entire industrial robot.

[0006] The first exemplary invention of the present application is an industrial robot, comprising: a working mechanism having a tool arranged on the front end side of an arm; and a driving device that drives the working mechanism, the driving device having: a motor; a wave generator, the cross section of which is perpendicular to the central axis is non-circular, and the wave generator can rotate around the central axis together with the rotating part of the motor; an external gear, at least a portion of which is arranged radially outside the wave generator, and the external gear has a plurality of external teeth protruding radially outward; and an internal gear, at least a portion of which is arranged radially outside the external gear, the internal gear expands in an annular shape with the central axis as the center, and has a plurality of internal teeth protruding radially inward and partially meshing with the plurality of external teeth, the tool can rotate together with the output part of either the external gear or the internal gear, and a plurality of strain gauges are arranged on the output part.

[0007] The exemplary second invention of the present application is a control system for an industrial robot, comprising: a plurality of industrial robots, each of which has an operating mechanism and a driving device, the operating mechanism having a tool arranged on the front end side of an arm, and the driving device driving the tool; and a control device, which receives output signals from a plurality of strain gauges arranged on the driving devices of each of the plurality of industrial robots and controls the plurality of driving devices, and when the output signal from at least one of the plurality of strain gauges deviates from a prescribed range, the control device stops the driving of all the operating mechanisms.

[0008] The third exemplary invention of the present application is a control method for multiple industrial robots, each of which has an operating mechanism and a driving device, wherein the operating mechanism has a tool arranged on the front end side of an arm, and the driving device drives the tool, and when an output signal from at least one of a plurality of strain gauges arranged on the driving device of each of the multiple industrial robots deviates from a prescribed range, the driving of all the operating mechanisms is stopped.

[0009] According to the exemplary first, second and third inventions of the present application, a strain gauge is arranged in the drive device itself to detect the torque applied to the tool, thereby making the entire industrial robot smaller than when a torque sensor is arranged separately from the drive device.

[0010] The above and other features, elements, steps, characteristics and advantages of the present invention will be more clearly understood from the following detailed description of preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the screw fastening device according to the first embodiment.

[0012] Figure 2 This is a diagram conceptually showing the configuration of a motor and a speed reducer, a working mechanism, and a control unit of the second drive device according to the first embodiment.

[0013] Figure 3 It is a longitudinal sectional view of the speed reducer of the first embodiment.

[0014] Figure 4 It is a transverse cross-sectional view of the speed reducer according to the first embodiment.

[0015] Figure 5 It is a partial longitudinal sectional view of the sensor substrate and the external gear according to the first embodiment.

[0016] Figure 6 It is a top view of the sensor substrate according to the first embodiment.

[0017] Figure 7 It is a partial plan view of the sensor substrate according to the first embodiment.

[0018] Figure 8 It is a partial plan view of the sensor substrate according to the first embodiment.

[0019] Fig. 9 This is a circuit diagram of a first bridge circuit of a first torque sensor according to a first embodiment.

[0020] Fig.10 This is a circuit diagram of a second bridge circuit of the second torque sensor according to the first embodiment.

[0021] Fig.11 It is a schematic diagram for explaining a control system of the screw fastening device according to the second embodiment. DETAILED DESCRIPTION

[0022] Hereinafter, the exemplary embodiments of the present application will be described with reference to the accompanying drawings. In the following description, sometimes the vertical direction and the like are described, but the expression shows the exemplary posture of each embodiment and does not limit the posture when the present invention is implemented. The posture can be appropriately changed within the scope of the gist of the present invention.

[0023] As an exemplary embodiment of the industrial robot of the present invention, a screw fastening device is described. However, the present invention can be applied to other industrial robots that perform the same operation as the screw fastening device without departing from the gist of the present invention.

[0024] <1. First embodiment>

[0025] <1-1. Structure of screw fastening device>

[0026] Figure 1 1 is a schematic diagram of a screw fastening device 100 according to a first embodiment. The screw fastening device 100 is a cooperative robot that fastens the screw 71 to a workpiece 72 by rotating the screw 71 through the rotation output by the second drive device 3 described later. Figure 1 As shown, the screw fastening device 100 includes a base 1, a first drive device 2, a second drive device 3, an arm 4, a control unit 5, and an operating mechanism 6. The second drive device 3 is a device that drives the operating mechanism 6. The second drive device 3 is an example of the "drive device" of the present invention. That is, the screw fastening device 100 includes the operating mechanism 6 and the drive device. The drive device drives the operating mechanism 6.

[0027] The base 1 is a table installed on a mounting surface such as a table or a floor on which the screw fastening device 100 is arranged. The base 1 rotatably supports one end of the arm 4. In addition, a stand 101 for supporting a workpiece 72 into which the screw 71 is screwed is provided adjacent to the base 1 on the mounting surface.

[0028] The arm 4 is supported by the base 1 at one end so as to be rotatable. The arm 4 has a plurality of joints 41. In the present embodiment, the arm 4 has three joints 41. The first drive device 2 is respectively assembled in two joints 41 close to one end among the three joints 41. On the other hand, the first drive device 2 is not assembled in the joint 41 closest to the other end of the arm 4 among the three joints 41. Hereinafter, the joint 41 closest to the other end of the arm 4 is referred to as the "joint 411". The wrist 45, which is a portion of the arm 4 closer to the other end than the joint 411, extends vertically downward from the joint 411.

[0029] In addition, a flange 46 is fixed to the other end of the arm 4 via a bearing (not shown). The flange 46 extends in a cylindrical shape in the vertical direction. However, as long as the working mechanism 6 is supported to be rotatable relative to the wrist 45 of the arm 4, the flange 46 may not be provided.

[0030] As described above, in the present embodiment, the two first drive devices 2 are respectively assembled to the joints 41 of the arm 4. Each of the first drive devices 2 has a motor 21 and a reducer 22. The motor 21 of the present embodiment has the same structure as the motor 31 of the second drive device 3 described later. In addition, the reducer 22 of the present embodiment has the same structure as the reducer 32 of the second drive device 3 described later. However, the motor 21 and the reducer 22 may have structures different from those of the motor 31 and the reducer 32 of the second drive device 3. When a driving current is supplied to the motor 21, a rotational motion is output from the rotating portion of the motor 21. The reducer 22 decelerates the rotational motion output from the rotating portion of the motor 21 and transmits it to the arm 4. As a result, the arm 4 rotates at a decelerated speed relative to the base 1 and each joint 41. As a result, the other end of the arm 4 can be moved to a desired position.

[0031] The second drive device 3 includes a motor 31 and a reducer 32. When a driving current is supplied to the motor 31, a rotational motion about a central axis 9 is output from the rotating portion of the motor 31. Here, the central axis 9 is a rotational central axis extending in a vertical direction. The reducer 32 reduces the rotational motion output from the rotating portion of the motor 31 and transmits it to a cutter head 61 (tool) described later of the working mechanism 6. As a result, the cutter head 61 rotates at a reduced speed. In addition, the detailed structure of the reducer 32 will be described later.

[0032] A retaining member 62 for retaining a tool head 61 is fixed to the lower surface of the flange portion 46. The tool head 61 is retained vertically downward by the retaining member 62. In addition, the tool head 61 of the present embodiment is supported together with the retaining member 62 and the flange portion 46 via the above-mentioned bearing so as to be rotatable around the vertical axis 91. Here, the vertical axis 91 is a rotation center axis extending in the vertical direction. In addition, in the present embodiment, the vertical axis 91 is completely consistent with the center axis 9. However, the vertical axis 91 may not be consistent with the center axis 9. The tool head 61 and the retaining member 62 constitute the working mechanism 6 as the end effector of the present embodiment. That is, the working mechanism 6 has a tool head 61 arranged on the front end side of the arm 4.

[0033] In addition, the cutter head 61 can be engaged with the screw 71 screwed into the workpiece 72 at the lower end. In addition, as described above, the cutter head 61 can rotate around the vertical axis 91 at a rotation speed reduced by the reducer 32. Therefore, in a state where the cutter head 61 is engaged with the screw 71, the screw 71 can be fastened to the workpiece 72 by rotating the cutter head 61.

[0034] The control unit 5 is a device for controlling the operation of each unit of the screw fastening device 100. The control unit 5 is composed of a computer or a circuit. Figure 1 As shown, the control unit 5 has a processor 51 such as a CPU, a memory 52 such as a RAM, and a storage unit 53 such as a hard disk drive. In addition, the storage unit 53 stores a program P for controlling the actions of each part of the screw fastening device 100. The function of the control unit 5 is realized by the processor 51, the memory 52 such as a RAM, and the storage unit 53 such as a hard disk drive acting according to the program P. The control unit 5 is an example of the "control unit" of the present invention. That is, the screw fastening device 100 also has a control unit. However, the control unit 5 can also be set outside the screw fastening device 100.

[0035] Figure 2 3 is a diagram conceptually showing the configuration of the motor 31 and the reducer 32 of the second drive device 3, the working mechanism 6, and the control unit 5. Figure 2 As shown, the torque sensor 8 for detecting the torque applied to the cutter head 61 is disposed in the speed reducer 32. The control unit 5 is electrically connected to the torque sensor 8 and the motor 31. The control unit 5 controls the motor 31 based on the detection value of the torque sensor 8 disposed in the speed reducer 32.

[0036] In addition, if Figure 1 and Figure 2 As shown, in this embodiment, the motor 31 is controlled based on the detection value of the torque sensor 8 arranged closer to the cutter head 61 than the motor 31. Thus, the motor 31 can be controlled while the state of the cutter head 61 is detected with high accuracy. As a result, the cutter head 61 can be operated with high accuracy.

[0037] In addition, a more detailed structure of the torque sensor 8 will be described later.

[0038] <1-2. Detailed structure of the speed reducer of the second drive device>

[0039] Next, a more detailed structure of the speed reducer 32 of the second drive device 3 will be described.

[0040] In addition, hereinafter, the direction parallel to the central axis 9 is referred to as the "axial direction", the direction perpendicular to the central axis 9 is referred to as the "radial direction", and the direction along the arc centered on the central axis 9 is referred to as the "circumferential direction". Figure 3 and Figure 5 In the description, the shape and positional relationship of each part are described with the direction of the central axis 9 of the reducer 32 being the left-right direction, the left side being the "one axial side", and the right side being the "other axial side". Figure 3 and Figure 5 In the above description, "one side in the axial direction" is represented by "a1" and "the other side in the axial direction" is represented by "a2". Figures 3 to 6 In the above, “radial direction” is represented by “r0”. Figure 4 and Figure 6 The “circumferential direction” is represented as “c0”.

[0041] However, it is not intended that the definition of the left-right direction limit the orientation of the screw fastening device of the present invention during manufacture and use. In addition, in the present application, the "parallel direction" is not limited to the situation that is strictly parallel in geometry. That is, the direction roughly parallel to a certain direction can be roughly parallel to the extent that the effect of the invention is achieved. In addition, in the present application, the "vertical direction" is not limited to the situation that is strictly perpendicular in geometry. That is, the direction roughly perpendicular to a certain direction can be roughly perpendicular to the extent that the effect of the invention is achieved.

[0042] Figure 3 It is a longitudinal sectional view of the speed reducer 32 of the second drive device 3 according to the first embodiment. Figure 4 is from Figure 3 The cross-sectional view of the reducer 32 observed from the AA position of FIG. Figure 4 In the figure, hatching lines indicating cross sections are omitted.

[0043] The reducer 32 is a wave gear reducer. The reducer 32 reduces the rotational motion of the first speed output from the motor 31 to a second speed slower than the first speed. Figure 3 and Figure 4As shown, the speed reducer 32 includes an input shaft 33, an internal gear 34, an external gear 35, and a wave generator 36. That is, the second drive device 3 includes the motor 31, the wave generator 36, the external gear 35, and the internal gear 34.

[0044] The input shaft 33 is a member extending in a cylindrical shape in the axial direction along the central axis 9 with the central axis 9 as the center. The input shaft 33 is connected to the rotating part of the motor 31, and rotates at the first rotation speed before deceleration together with the rotating part of the motor 31. In addition, the input shaft 33 may also be the same member as the rotating part of the motor 31.

[0045] The internal gear 34 is a gear fixed to the wrist 45 of the arm 4. The internal gear 34 is arranged radially outward of a portion near the external teeth 352 described later in the external gear 35. That is, at least a portion of the internal gear 34 is arranged radially outward of the external gear 35. The rigidity of the internal gear 34 is sufficiently higher than the rigidity of the body 351 of the external gear 35 described later.

[0046] The internal gear 34 is in the shape of an annulus with the central axis 9 as the center. That is, the internal gear 34 is expanded in the shape of an annulus with the central axis 9 as the center. In addition, the internal gear 34 has a plurality of internal teeth 341. The plurality of internal teeth 341 protrude radially inward from the inner circumferential surface of the internal gear 34. In addition, the plurality of internal teeth 341 are arranged at a constant pitch along the circumferential direction on the inner circumferential surface of the internal gear 34. A portion of the plurality of internal teeth 341 meshes with a portion of a plurality of external teeth 352 described later of the external gear 35. That is, the internal gear 34 has a plurality of internal teeth 341 that protrude radially inward and partially mesh with the plurality of external teeth 352.

[0047] The external gear 35 is a ring-shaped gear that can bend and deform. The external gear 35 is connected to the cutter head 61 of the working mechanism 6 directly or via other components. In this embodiment, the external gear 35 is connected to the cutter head 61 via a connecting component (not shown) in a manner that is non-rotatable relative to the cutter head 61. Figure 3 and Figure 4 As shown, the external gear 35 includes a body portion 351, a plurality of external teeth 352, a diaphragm portion 353, and a thick portion 354. However, the structure of the external gear 35 may be different from the structure described below.

[0048] The body 351 is a portion extending in a cylindrical shape along the central axis 9 with the central axis 9 as the center. One axial end of the body 351 is connected to the diaphragm 353. The body 351 extends from the radial inner end of the diaphragm 353 toward the other axial side. The other axial end of the body 351 is located radially outside the wave generator 36 and radially inside the internal gear 34. That is, at least a portion of the external gear 35 is arranged radially outside the wave generator 36. The body 351 has flexibility and can be bent and deformed in the radial direction.

[0049] The plurality of external teeth 352 protrude radially outward from the radial outer side of the body 351. That is, the external gear 35 has the plurality of external teeth 352 protruding radially outward. In addition, the plurality of external teeth 352 are arranged on the radial outer side of the portion near the other axial end of the body 351. The plurality of external teeth 352 are arranged at a constant pitch in the circumferential direction. As described above, a portion of the plurality of external teeth 352 meshes with a portion of the plurality of internal teeth 341 of the internal gear 34. The number of internal teeth 341 of the internal gear 34 is slightly different from the number of external teeth 352 of the external gear 35.

[0050] The diaphragm portion 353 surrounds the central axis 9 and extends in a direction intersecting the central axis 9. The diaphragm portion 353 preferably extends along a plane perpendicular to the central axis 9. The diaphragm portion 353 extends radially outward from one axial end of the body portion 351. In addition, the diaphragm portion 353 is annular and surrounds the central axis 9. The diaphragm portion 353 is thin-walled and can be slightly deformed.

[0051] The thick wall portion 354 is an annular portion centered on the central axis 9 and located radially outward of the diaphragm portion 353. The axial thickness of the thick wall portion 354 is thicker than the axial thickness of the diaphragm portion 353. In the present embodiment, the thick wall portion 354 is connected to the cutter head 61 via a connecting member (not shown) in a non-rotatable manner. In addition, the thick wall portion 354 is supported by the cross roller bearing 150 so as to be rotatable relative to the internal gear 34. The cross roller bearing 150 includes an outer ring 152, an inner ring 151, and rollers 161. In addition, in the present embodiment, the outer ring 152 is fixed to the other axial side of the thick wall portion 354, and the outer ring 152 is rotatably supported by the inner ring 151 fixed to the wrist portion 45 of the arm 4 via the rollers 161. That is, in the present embodiment, the external gear 35 including the thick wall portion 354 is supported by the wrist portion 45 of the arm 4 so as to be rotatable around the central axis 9.

[0052] The wave generator 36 is a mechanism that causes the external gear 35 to generate periodic flexural deformation. The wave generator 36 is arranged radially inward of the external teeth 352. The wave generator 36 has a cam 361 and a flexible bearing 362. In the present embodiment, the input shaft 33 and the cam 361 are formed by a single component. However, the cam 361 may also be a component different from the input shaft 33. In this case, it is sufficient to fix the cam 361 relative to the input shaft 33. Thus, the input shaft 33 and the cam 361 rotate together with the rotating part of the motor 31 at the first speed before deceleration. That is, the wave generator 36 can rotate around the central axis 9 together with the rotating part of the motor 31. In addition, in addition to the input shaft 33 and the cam 361, the rotating part of the motor 31 may also be formed by a single component.

[0053] The cam 361 is a member that applies displacement at a period of 180° to the external gear 35. The radially outer side surface of the cam 361 is elliptical centered on the central axis 9. That is, the cross section of the wave generator 36 perpendicular to the central axis 9 is non-circular.

[0054] The flexible bearing 362 is a bearing that can be flexibly deformed. The flexible bearing 362 is arranged between the radial outer side surface of the cam 361 and the radial inner side surface of the body 351 of the external gear 35. The inner ring of the flexible bearing 362 contacts the radial outer side surface of the cam 361. The outer ring of the flexible bearing 362 contacts the radial inner side surface of the body 351. Therefore, the body 351 is deformed into an elliptical shape along the radial outer side surface of the cam 361 due to being pressed from the radial inside by the cam 361. As a result, the outer teeth 352 of the external gear 35 mesh with the inner teeth 341 of the internal gear 34 at two locations corresponding to the two ends of the major axis of the ellipse. At other positions in the circumferential direction, the outer teeth 352 and the inner teeth 341 do not mesh.

[0055] When the motor 31 is driven, the cam 361 rotates at the first speed with the rotating part of the motor 31 and the input shaft 33 about the central axis 9. As a result, the major axis of the ellipse of the external gear 35 also rotates at the first speed. Then, the meshing position of the external teeth 352 and the internal teeth 341 also changes in the circumferential direction at the first speed. In addition, as described above, the number of internal teeth 341 of the internal gear 34 is slightly different from the number of external teeth 352 of the external gear 35. Due to the difference in the number of teeth, the meshing position of the external teeth 352 and the internal teeth 341 changes slightly in the circumferential direction every time the cam 361 rotates one circle.

[0056] Here, the internal gear 34 having the internal teeth 341 is fixed to the wrist 45 of the arm 4 and does not rotate. On the other hand, as described above, the external gear 35 having the external teeth 352 is supported by the wrist 45 of the arm 4 so as to be rotatable around the central axis 9. Thus, in the present embodiment, the external gear 35 rotates at a second speed slower than the first speed with respect to the internal gear 34 about the central axis 9. As a result, the cutter head 61 connected to the external gear 35 rotates at the second speed with the vertical axis 91 as the center. That is, the external gear 35 of the present embodiment is an example of the "output portion" of the present invention.

[0057] <1-3. Detailed structure of torque sensor>

[0058] Next, a more detailed structure of the torque sensor 8 will be described.

[0059] As described above, the torque sensor 8 is disposed on the reducer 32. Figure 3 As shown, the torque sensor 8 includes a sensor substrate 80 . The sensor substrate 80 is fixed to the surface of the diaphragm portion 353 .

[0060] Figure 5 It is a partial longitudinal sectional view of the sensor substrate 80 and the external gear 35 . Figure 6 is a top view of the sensor substrate 80. Figure 5 As shown, the sensor substrate 80 has an insulating layer 801 and a conductive layer 802 .

[0061] The insulating layer 801 is a part that can be flexibly deformed. The insulating layer 801 is made of a resin or an inorganic insulating material as an insulator. The insulating layer 801 extends in a direction intersecting the central axis 9. In addition, the insulating layer 801 is in a circular ring shape centered on the central axis 9. The insulating layer 801 is arranged on the surface of the diaphragm part 353 facing the axial side.

[0062] The conductor layer 802 is a portion formed on the surface of the insulating layer 801 facing the axial side. A metal that is a conductor is used as the material of the conductor layer 802. Specifically, the material of the conductor layer 802 is, for example, a copper alloy, a chromium alloy, or copper. The conductor layer 802 has a plurality of strain gauges. That is, a plurality of strain gauges are arranged at the output portion of the external gear 35 as the present embodiment. The function of the torque sensor 8 is mainly realized by using the plurality of strain gauges.

[0063] The torque sensor 8 detects the torque applied to the diaphragm portion 353 using the plurality of strain gauges, thereby being able to detect the torque applied to the cutter head 61. Specifically, the output signal of the torque sensor 8 changes according to the torque applied to the diaphragm portion 353. Thus, the torque applied to the cutter head 61 connected to the external gear 35 having the diaphragm portion 353 can be detected based on the output signal from the torque sensor 8. As a result, the rotational torque applied to the screw 71 engaged with the cutter head 61 can be detected. This will be described in further detail below.

[0064] like Figure 6 As shown, the torque sensor 8 includes a first torque sensor W1 and a second torque sensor W2. The second torque sensor W2 is arranged at a position radially outward of the first torque sensor W1. The first torque sensor W1 and the second torque sensor W2 each have a plurality of strain gauges. Hereinafter, the plurality of strain gauges possessed by the first torque sensor W1 will be referred to as "first strain gauges", and the plurality of strain gauges possessed by the second torque sensor W2 will be referred to as "second strain gauges". That is, the plurality of strain gauges that realize the function of the torque sensor 8 include a plurality of first strain gauges and a plurality of second strain gauges. Moreover, the plurality of second strain gauges are arranged at a position radially outward of the plurality of first strain gauges.

[0065] In addition, the first torque sensor W1 has four strain gauges Ra, Rb, Rc, and Rd. That is, the plurality of first strain gauges include four strain gauges Ra, Rb, Rc, and Rd. Two strain gauges Ra and Rb among the four strain gauges Ra, Rb, Rc, and Rd are arranged at intervals from each other in the circumferential direction. In the present embodiment, the two strain gauges Ra and Rb are respectively arranged in a semicircular arc shape within a range of about 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Ra is substantially the same as the radial distance from the central axis 9 to the strain gauge Rb.

[0066] The other two strain gauges Rc and Rd of the four strain gauges Ra, Rb, Rc, and Rd are arranged radially outward from the two strain gauges Ra and Rb. The two strain gauges Rc and Rd are arranged at intervals from each other in the circumferential direction. In the present embodiment, the two strain gauges Rc and Rd are respectively arranged in a semicircular arc shape within a range of about 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Rc is substantially the same as the radial distance from the central axis 9 to the strain gauge Rd.

[0067] As described above, the two strain gauges Rc and Rd are arranged at positions radially outward from the two strain gauges Ra and Rb. Therefore, the two strain gauges Ra and Rb can be respectively referred to as "inner strain gauges", and the two strain gauges Rc and Rd can be respectively referred to as "outer strain gauges". That is, the plurality of strain gauges that realize the function of the torque sensor 8 include a plurality of inner strain gauges Ra and Rb and a plurality of outer strain gauges Rc and Rd. Moreover, the plurality of inner strain gauges Ra and Rb are arranged in the circumferential direction. In addition, the plurality of outer strain gauges Rc and Rd are arranged in the circumferential direction at positions radially outward from the plurality of inner strain gauges Ra and Rb.

[0068] In addition, two inner gap regions Gi are arranged between the inner strain gauges Ra and Rb adjacent in the circumferential direction. That is, the inner gap region Gi is arranged between the inner strain gauges Ra and Rb adjacent in the circumferential direction. In addition, when viewed from the axial direction, the two inner gap regions Gi are arranged at an angular interval of 180° with the central axis 9 as the center. That is, the plurality of inner gap regions Gi are arranged at an angular interval of 180° with the central axis 9 as the center.

[0069] In addition, two outer gap regions Go are arranged between the outer strain gauges Rc and Rd adjacent in the circumferential direction. That is, the outer gap region Go is arranged between the outer strain gauges Rc and Rd adjacent in the circumferential direction. In addition, when viewed from the axial direction, the two outer gap regions Go are arranged at an angular interval of 180° with the central axis 9 as the center. That is, the plurality of outer gap regions Go are arranged at an angular interval of 180° with the central axis 9 as the center. In addition, the inner gap region Gi is adjacent to the outer gap region Go in the radial direction.

[0070] In addition, the two strain gauges Ra and Rc are arranged concentrically and line-symmetrically with the two strain gauges Rb and Rd.

[0071] The strain gauges Ra, Rb, Rc, and Rd are patterns extending in the circumferential direction while being bent in a zigzag shape. Figure 7 and Figure 8 They are partial top views of the sensor substrate 80. Figure 7 and Figure 8 As shown, each of the strain gauges Ra, Rb, Rc, and Rd has a plurality of resistance lines r1 arranged in the circumferential direction and substantially parallel to each other. Each resistance line r1 extends in a direction having both radial and circumferential components.

[0072] The resistance wire r1 of the strain gauges Ra and Rd is inclined toward one side of the circumferential direction relative to the radial direction. The resistance wire r1 of the strain gauges Rb and Rc is inclined toward the other side of the circumferential direction relative to the radial direction. The inclination angle of the resistance wire r1 relative to the radial direction is, for example, 45°. The ends of the resistance wires r1 adjacent to each other in the circumferential direction are alternately connected to each other in the radial direction inward or radial direction outward. Thus, the plurality of resistance wires r1 are connected in series as a whole.

[0073] Fig. 9 : is a circuit diagram of the first bridge circuit C1 including the four strain gauges Ra, Rb, Rc, and Rd of the first torque sensor W1. Fig. 9 As shown, the four strain gauges Ra, Rb, Rc, and Rd are connected to each other to form a first bridge circuit C1. That is, the first bridge circuit C1 is formed by the plurality of first strain gauges constituting the first torque sensor W1. That is, the first bridge circuit C1 is formed by the plurality of inner strain gauges Ra and Rb and the plurality of outer strain gauges Rc and Rd constituting the first torque sensor W1.

[0074] The strain gauge Ra and the strain gauge Rb are connected in series. The strain gauge Rc and the strain gauge Rd are connected in series. Moreover, between the + pole and the - pole of the power supply voltage, the column of the two strain gauges Ra and Rb is connected in parallel with the column of the two strain gauges Rc and Rd. In addition, the first voltmeter V1 is connected between the middle point M11 of the two strain gauges Ra and Rb and the middle point M12 of the two strain gauges Rc and Rd.

[0075] The resistance value of each resistance wire r1 changes according to the torque applied to the area where the resistance wire r1 is configured. For example, when a torque is applied to the diaphragm portion 353 toward one side in the circumferential direction with the central axis 9 as the center, the resistance value of each resistance wire r1 of the two strain gauges Ra and Rd increases, and the resistance value of each resistance wire r1 of the other two strain gauges Rb and Rc decreases. On the other hand, when a torque is applied to the diaphragm portion 353 toward the other side in the circumferential direction with the central axis 9 as the center, the resistance value of each resistance wire r1 of the two strain gauges Ra and Rd decreases, and the resistance value of each resistance wire r1 of the other two strain gauges Rb and Rc increases. In this way, the two strain gauges Ra and Rd and the other two strain gauges Rb and Rc show resistance value changes in opposite directions relative to the torque.

[0076] When the resistance values ​​of the four strain gauges Ra, Rb, Rc, and Rd change, the potential difference between the middle point M11 of the two strain gauges Ra and Rb and the middle point M12 of the two strain gauges Rc and Rd changes, so the measurement value of the first voltmeter V1 also changes.

[0077] Here, if Figure 3 As shown, the second drive device 3 further includes a signal processing circuit 85. The signal processing circuit 85 is composed of a circuit having a microprocessor. The signal processing circuit 85 is electrically connected to the first bridge circuit C1 of the torque sensor 8. The signal processing circuit 85 detects the direction and magnitude of the torque applied to the diaphragm portion 353 based on the measurement value of the first voltmeter V1. In addition, the signal processing circuit 85 sends data related to the direction and magnitude of the torque applied to the diaphragm portion 353 detected to the control unit 5.

[0078] Then, the control unit 5 controls the driving of the motor 21 of the first drive device 2 and the motor 31 of the second drive device 3 according to the data related to the direction and magnitude of the torque applied to the diaphragm portion 353 received from the signal processing circuit 85. For example, when the magnitude of the torque applied to the diaphragm portion 353 is within a specified range, the control unit 5 determines that an appropriate rotational driving force is applied to the cutter head 61 and the screw 71. When the magnitude of the torque applied to the diaphragm portion 353 exceeds a specified value (i.e., the state in which the screw 71 is tightened), the control unit 5 determines that an excessive rotational driving force is applied to the cutter head 61 and the screw 71. In this case, the control unit 5 temporarily stops the driving of the motor 31 of the second drive device 3. Thus, it is possible to avoid damage to the screw 71, the workpiece 72, etc. In addition, for example, when the magnitude of the torque applied to the diaphragm portion 353 is zero, the control unit 5 determines that the cutter head 61 is not properly engaged with the screw 71. In this case, the control unit 5 controls the driving of the motor 21 of the first driving device 2 to move the other end of the arm 4 to an appropriate position.

[0079] In addition, as described above, in the first torque sensor W1 of the present embodiment, a plurality of inner strain gauges Ra and Rb arranged circumferentially in the radial direction and a plurality of outer strain gauges Rc and Rd arranged circumferentially in the radial direction are provided. In addition, the first bridge circuit C1 is formed by the plurality of inner strain gauges Ra and Rb and the plurality of outer strain gauges Rc and Rd. Thus, even when the angular position of the major axis of the cam 361 of the wave generator 36 changes around the central axis 9, the influence on the measurement result of the torque applied to the diaphragm portion 353 can be suppressed, so that the torque can be measured more accurately.

[0080] Next, the second torque sensor W2 has four strain gauges Re, Rf, Rg, and Rh. That is, the plurality of second strain gauges include four strain gauges Re, Rf, Rg, and Rh. Two strain gauges Re and Rf among the four strain gauges Re, Rf, Rg, and Rh are arranged at intervals from each other in the circumferential direction. In the present embodiment, the two strain gauges Re and Rf are respectively arranged in a semicircular arc shape within a range of about 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Re is approximately the same as the radial distance from the central axis 9 to the strain gauge Rf.

[0081] The other two strain gauges Rg and Rh of the four strain gauges Re, Rf, Rg, and Rh are arranged at radially outer positions than the above two strain gauges Re and Rf. The two strain gauges Rg and Rh are arranged at intervals from each other in the circumferential direction. In the present embodiment, the two strain gauges Rg and Rh are respectively arranged in a semicircular arc shape within a range of about 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Rg is substantially the same as the radial distance from the central axis 9 to the strain gauge Rh.

[0082] As described above, the two strain gauges Rg and Rh are arranged at positions radially outward from the two strain gauges Re and Rf. Therefore, the two strain gauges Re and Rf can be respectively referred to as "inner strain gauges", and the two strain gauges Rg and Rh can be respectively referred to as "outer strain gauges". That is, the plurality of strain gauges that realize the function of the torque sensor 8 include a plurality of inner strain gauges Re and Rf and a plurality of outer strain gauges Rg and Rh. Moreover, the plurality of inner strain gauges Re and Rf are arranged in the circumferential direction. In addition, the plurality of outer strain gauges Rg and Rh are arranged in the circumferential direction at positions radially outward from the plurality of inner strain gauges Re and Rf.

[0083] In addition, two inner gap regions Gi are arranged between the inner strain gauges Re and Rf adjacent in the circumferential direction. That is, the inner gap region Gi is arranged between the inner strain gauges Re and Rf adjacent in the circumferential direction. In addition, when viewed from the axial direction, the two inner gap regions Gi are arranged at an angular interval of 180° with the central axis 9 as the center. That is, the plurality of inner gap regions Gi are arranged at an angular interval of 180° with the central axis 9 as the center.

[0084] In addition, two outer gap regions Go are arranged between the circumferentially adjacent outer strain gauges Rg and Rh. That is, the outer gap region Go is arranged between the circumferentially adjacent outer strain gauges Rg and Rh. In addition, when viewed from the axial direction, the two outer gap regions Go are arranged at an angular interval of 180° with the central axis 9 as the center. That is, a plurality of outer gap regions Go are arranged at an angular interval of 180° with the central axis 9 as the center. In addition, the inner gap region Gi is adjacent to the outer gap region Go in the radial direction. Thus, the inner strain gauges Re, Rf and the outer strain gauges Rg, Rh can be arranged in the widest possible area in the circumferential direction to improve the detection accuracy of the torque, and simplify the structure of the sensor substrate 80 or the wiring of the second bridge circuit C2 described later.

[0085] In addition, the two strain gauges Re and Rg are arranged concentrically and line-symmetrically with the two strain gauges Rf and Rh.

[0086] The strain gauges Re, Rf, Rg, and Rh are patterns that are bent in a zigzag shape while extending in the circumferential direction. Figure 7 and Figure 8 As shown, each strain gauge Re, Rf, Rg, Rh has a plurality of resistance lines r2 arranged in the circumferential direction and substantially parallel to each other. Each resistance line r2 extends in a direction having both radial and circumferential components.

[0087] The resistance wire r2 of the strain gauges Re and Rh is inclined toward one side of the circumferential direction relative to the radial direction. The resistance wire r2 of the strain gauges Rf and Rg is inclined toward the other side of the circumferential direction relative to the radial direction. The inclination angle of the resistance wire r2 relative to the radial direction is, for example, 45°. The ends of the resistance wires r2 adjacent to each other in the circumferential direction are alternately connected to each other in the radial direction inward or radial direction outward. Thus, the plurality of resistance wires r2 are connected in series as a whole.

[0088] Fig.10 : is a circuit diagram of the second bridge circuit C2 including the four strain gauges Re, Rf, Rg, and Rh of the second torque sensor W2. Fig.10As shown, the four strain gauges Re, Rf, Rg, and Rh are connected to each other to form a second bridge circuit C2. That is, the plurality of second strain gauges constituting the second torque sensor W2 constitute the second bridge circuit C2. That is, the plurality of inner strain gauges Re and Rf and the plurality of outer strain gauges Rg and Rh constituting the second torque sensor W2 constitute the second bridge circuit C2.

[0089] The strain gauge Re and the strain gauge Rf are connected in series. The strain gauge Rg and the strain gauge Rh are connected in series. Moreover, between the + pole and the - pole of the power supply voltage, the column of the two strain gauges Re and Rf is connected in parallel with the column of the two strain gauges Rg and Rh. In addition, the second voltmeter V2 is connected between the middle point M21 of the two strain gauges Re and Rf and the middle point M22 of the two strain gauges Rg and Rh.

[0090] The resistance value of each resistance wire r2 changes according to the torque applied to the area where the resistance wire r2 is configured. For example, when a torque is applied to the diaphragm portion 353 toward one side in the circumferential direction with the central axis 9 as the center, the resistance value of each resistance wire r2 of the two strain gauges Re and Rh increases, and the resistance value of each resistance wire r2 of the other two strain gauges Rf and Rg decreases. On the other hand, when a torque is applied to the diaphragm portion 353 toward the other side in the circumferential direction with the central axis 9 as the center, the resistance value of each resistance wire r2 of the two strain gauges Re and Rh decreases, and the resistance value of each resistance wire r2 of the other two strain gauges Rf and Rg increases. In this way, the two strain gauges Re and Rh and the other two strain gauges Rf and Rg show resistance value changes in opposite directions relative to the torque.

[0091] When the resistance values ​​of the four strain gauges Re, Rf, Rg, and Rh change, the potential difference between the middle point M21 of the two strain gauges Re and Rf and the middle point M22 of the two strain gauges Rg and Rh changes, so the measurement value of the second voltmeter V2 also changes.

[0092] In addition, the signal processing circuit 85 is also electrically connected to the second bridge circuit C2 of the torque sensor 8. The signal processing circuit 85 detects the direction and magnitude of the torque applied to the diaphragm portion 353 based on the measurement value of the second voltmeter V2. In addition, the signal processing circuit 85 sends data related to the direction and magnitude of the torque applied to the diaphragm portion 353 detected to the control unit 5.

[0093] Then, the control unit 5 can control the driving of the motor 21 of the first drive device 2 and the motor 31 of the second drive device 3 based on the data related to the direction and magnitude of the torque applied to the diaphragm portion 353, which is detected based on the measurement value of the second voltmeter V2 and received from the signal processing circuit 85. That is, the control unit 5 receives the output signals from the plurality of first strain gauges and the output signals from the plurality of second strain gauges to control the drive devices.

[0094] In addition, as described above, in the second torque sensor W2 of the present embodiment, a plurality of inner strain gauges Re and Rf arranged circumferentially in the radial direction and a plurality of outer strain gauges Rg and Rh arranged circumferentially in the radial direction are provided. In addition, the second bridge circuit C2 is formed by the plurality of inner strain gauges Re and Rf and the plurality of outer strain gauges Rg and Rh. Thus, even when the angular position of the major axis of the cam 361 of the wave generator 36 changes around the central axis 9, the influence on the measurement result of the torque applied to the diaphragm portion 353 can be suppressed, so that the torque can be measured more accurately.

[0095] In addition, as described above, in this embodiment, a plurality of strain gauges are arranged in the second drive device 3 itself, and based on the outputs of the plurality of strain gauges, it is possible to detect the torque applied to the diaphragm portion 353 and the rotational torque applied to the bit 61 and the screw 71. Thus, compared with the case where a torque sensor is arranged separately from the second drive device 3, the entire screw fastening device 100 can be miniaturized.

[0096] In addition, as described above, the screw fastening device 100 of the present embodiment has two torque sensors W1 and W2. Therefore, the control unit 5 can compare the data detected based on the measurement value of the first voltmeter V1 of the first torque sensor W1 with the data detected based on the measurement value of the second voltmeter V2 of the second torque sensor W2. Thus, if the data of either side is too large, the control unit 5 can easily understand which sensor has an abnormality.

[0097] That is, in the present embodiment, when an abnormality occurs in any one of the first strain gauge constituting the first torque sensor W1 and the second strain gauge constituting the second torque sensor W2 , the abnormality can be easily detected.

[0098] In addition, when the difference between the data detected based on the measurement value of the first voltmeter V1 of the first torque sensor W1 and the data detected based on the measurement value of the second voltmeter V2 of the second torque sensor W2 is too large, the control unit 5 can also stop the drive of the screw fastening device 100 until the cause is determined and dealt with. That is, when the relationship between the output signals from the plurality of first strain gauges and the output signals from the plurality of second strain gauges deviates from a prescribed range, the control unit 5 stops the drive of the working mechanism 6. Thus, when an abnormality occurs, the drive of the screw fastening device 100 can be stopped.

[0099] <2. Second Embodiment>

[0100] Next, the control system of the industrial robot and the control method of multiple industrial robots of the present invention are described. The control system 200B for controlling the screw fastening device 100B of the second embodiment of the present invention is described. In addition, the following description focuses on the differences from the screw fastening device 100 of the first embodiment, and a part of the repeated description of the same parts as the first embodiment is omitted.

[0101] Fig.11 2 is a schematic diagram for explaining a control system 200B of the present embodiment. The control system 200B of the present embodiment is applied to a space where a plurality of screw fastening devices 100B are arranged as cooperative robots cooperating with operators in a production line of a factory, for example. Fig.11 As shown, the control system 200B has a plurality of screw fastening devices 100B and a control device 210B. The control device 210B is an example of the "control device" of the present invention. In addition, in the control system 200B of this embodiment, a "control unit 5B" equivalent to the "control unit 5" of the first embodiment is respectively provided in the plurality of screw fastening devices 100B. However, the "control unit 5B" equivalent to the "control unit 5" of the first embodiment may not be provided, and the control device 210B may also have the function of the "control unit 5B". In addition, the control device 210B may also be provided outside the control system 200B.

[0102] The plurality of screw fastening devices 100B of the present embodiment each have a structure equivalent to the screw fastening device 100 of the first embodiment. That is, the plurality of screw fastening devices 100B each have: an operating mechanism 6B having a cutter head 61B disposed on the front end side of the arm 4B; and a second drive device 3B as a drive device, which drives the cutter head 61B to rotate the cutter head 61B. In addition, a torque sensor composed of a plurality of strain gauges is disposed on the external gear as the output portion of the reducer of each second drive device 3B. In addition, the control unit 5B and the control device 210B of each screw fastening device 100B are electrically connected to the torque sensor and the motor of the second drive device 3B, respectively. Moreover, as in the first embodiment, the torque sensor detects the direction and magnitude of the torque applied to the diaphragm portion of the external gear, and sends data related to the detection result to the control unit 5B. In addition, in the present embodiment, the torque sensor further sends data related to the detection result of the direction and magnitude of the torque applied to the diaphragm portion of the external gear to the control device 210B.

[0103] The control device 210B receives output signals from a plurality of strain gauges disposed in the second drive devices 3B of the plurality of screw fastening devices 100B and controls the plurality of second drive devices 3B. The control device 210B is composed of a computer or a circuit. Fig.11 As shown, the control device 210B includes a processor 211B such as a CPU, a memory 212B such as a RAM, and a storage unit 213B such as a hard disk drive. The storage unit 213B stores a program 214P for controlling the operation of the control system 200B. The control device 210B operates according to the program 214P.

[0104] Then, the control device 210B of the present embodiment stops the driving of the operating mechanism 6B of all the screw fastening devices 100B possessed by the control system 200B when the output signal from at least one of the plurality of strain gauges disposed in the second drive device 3B of each of the plurality of screw fastening devices 100B deviates from the prescribed range. That is, when an abnormality occurs, the driving of all the screw fastening devices 100B can be stopped. Thus, when an abnormality is found in any of the screw fastening devices 100B, the driving of all the screw fastening devices 100B can be stopped until the cause is determined and dealt with. As a result, the safety of the operator can be ensured and the occurrence of deviations in the progress of the operating process in the production line, etc. can be suppressed. In addition, the driving of the operating mechanism 61B is stopped both during normal operation and when the tightening of the screw 71 is completed.

[0105] That is, the control method of the plurality of screw fastening devices 100B of the present embodiment relates to a plurality of screw fastening devices 100B each having a working mechanism 6B and a second drive device 3B, wherein the working mechanism 6B has a cutter head 61B disposed on the front end side of the arm 4B, and the second drive device 3B is a drive device that drives the cutter head 61B to rotate the cutter head 61B. Then, when the output signal from at least one of the plurality of strain gauges disposed in the respective drive devices of the plurality of screw fastening devices 100B, i.e., the second drive device 3B, deviates from a prescribed range, the drive of all the working mechanisms 6B is stopped. Thus, similarly to the above, when an abnormality occurs, the drive of all the screw fastening devices 100B can be stopped. In addition, the drive of the working mechanism 61B is stopped both during normal operation and when the tightening of the screw 71 is completed.

[0106] <3. Modifications>

[0107] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment.

[0108] In the above-mentioned embodiment, the internal gear 34 having the internal teeth 341 is fixed to the wrist 45 of the arm 4 and does not rotate, while the external gear 35 having the external teeth 352 has a structure that can rotate around the central axis 9 together with the cutter head 61. However, it is also possible to configure that the external gear 35 having the external teeth 352 is fixed to the wrist 45 of the arm 4 and does not rotate, while the internal gear 34 having the internal teeth 341 can rotate around the central axis 9 together with the cutter head 61. In this case, the internal gear 34 becomes an example of the "output portion" of the present invention. That is, the cutter head 61 only needs to be able to rotate together with the output portion of either the external gear 35 or the internal gear 34.

[0109] In addition, in the above-mentioned embodiment, a plurality of strain gauges are arranged on the diaphragm portion 353 of the external gear 35 as the output portion. However, a plurality of strain gauges may be arranged on the internal gear 34 fixed to the wrist portion 45 of the arm 4. In this case, according to the law of action and reaction, the torque applied to the diaphragm portion 353 and the rotational torque applied to the cutter head 61 and the screw 71 can also be detected based on the reaction force applied to the internal gear 34. Furthermore, even in the case where the external gear 35 is fixed and the internal gear 34 serves as the output portion as in the above-mentioned modification, a plurality of strain gauges may be arranged on the internal gear 34 or on the external gear 35. That is, it is sufficient as long as a plurality of strain gauges are arranged on at least one of the external gear 35 and the internal gear 34.

[0110] However, as described above, the external gear 35 is flexible, while the internal gear 34 is sufficiently rigid and is difficult to bend. Therefore, it is preferable to configure a plurality of strain gauges on the flexible external gear 35. As a result, the change in the output signal from the strain gauge becomes larger, so that the torque can be detected with higher sensitivity and high accuracy.

[0111] In the above embodiment, the first torque sensor W1 and the second torque sensor W2 each have two inner strain gauges and two outer strain gauges. However, the first torque sensor W1 and the second torque sensor W2 may each have four inner strain gauges and four outer strain gauges so as to form a bridge circuit. Furthermore, the inner strain gauges and the outer strain gauges may be arranged at intervals in the circumferential direction.

[0112] The external gear 35 of the above embodiment is a so-called "hat-shaped" gear in which the diaphragm portion 353 extends radially outward from the body portion 351. However, the external gear 35 may be a so-called "cup-shaped" gear in which the diaphragm portion 353 extends radially inward from the body portion 351.

[0113] The screw fastening device 100 or 100B in the above embodiment has been described as fastening the screw 71 , but the present invention is also applicable to a case where the screw 71 is removed when the rotation direction output by the second drive device 3 or 3B is reversed.

[0114] The screw fastening device 100, 100B of the above-mentioned embodiment is a collaborative robot having a tool head 61, 61B in the working mechanism 6, 6B and capable of fastening or removing the screw 71, but the industrial robot of the present invention can also be used as other industrial robots by installing other tools in the working mechanism 6, 6B. For example, a cover opening and closing device for tightening or removing a cover on a container of drinking water or medicine, a mixer for stirring a liquid in a container, a drilling machine for drilling a hole in a workpiece, a processing device for grinding or cutting the surface of a workpiece, etc.

[0115] Furthermore, the detailed structures of the industrial robot and the control system of the industrial robot may be appropriately changed without departing from the gist of the present invention. In addition, the elements in the above-mentioned embodiments and modified examples may be appropriately combined without causing any contradiction.

[0116] <4. Conclusion>

[0117] The present technology can adopt the following structures.

[0118] (1) An industrial robot, comprising: a working mechanism having a tool disposed on the front end side of an arm; and a driving device that drives the working mechanism, the driving device having: a motor; a wave generator having a non-circular cross-section perpendicular to a central axis, the wave generator being rotatable around the central axis together with a rotating portion of the motor; an external gear, at least a portion of which is disposed radially outward of the wave generator, the external gear having a plurality of external teeth protruding radially outward; and an internal gear, at least a portion of which is disposed radially outward of the external gear, the internal gear extending in an annular shape with the central axis as a center and having a plurality of internal teeth protruding radially inward and partially meshing with the plurality of external teeth, the tool being rotatable together with an output portion of either the external gear or the internal gear, and a plurality of strain gauges being disposed on at least one of the external gear and the internal gear.

[0119] (2) The industrial robot according to (1), wherein the plurality of strain gauges are arranged on the external gear.

[0120] (3) An industrial robot according to (1) or (2), wherein the plurality of strain gauges comprises: a plurality of inner strain gauges arranged circumferentially; and a plurality of outer strain gauges arranged circumferentially at positions radially outward of the plurality of inner strain gauges, wherein a bridge circuit is formed by the plurality of inner strain gauges and the plurality of outer strain gauges.

[0121] (4) An industrial robot according to (3), wherein an inner gap area is arranged between the circumferentially adjacent inner strain gauges, and a plurality of the inner gap areas are arranged at angular intervals of 180° with the central axis as the center, and an outer gap area is arranged between the circumferentially adjacent outer strain gauges, and a plurality of the outer gap areas are arranged at angular intervals of 180° with the central axis as the center, and the inner gap area is radially adjacent to the outer gap area.

[0122] (5) An industrial robot according to any one of (1) to (4), wherein the plurality of strain gauges comprises: a plurality of first strain gauges, the plurality of first strain gauges constituting a first bridge circuit; and a plurality of second strain gauges, the plurality of second strain gauges being arranged radially outwardly of the plurality of first strain gauges to constitute a second bridge circuit.

[0123] (6) An industrial robot according to (5), wherein the industrial robot further comprises a control unit which receives output signals from the plurality of first strain gauges and output signals from the plurality of second strain gauges to control the drive device, and when the relationship between the output signals from the plurality of first strain gauges and the output signals from the plurality of second strain gauges deviates from a prescribed range, the control unit stops the drive of the working mechanism.

[0124] (7) A control system for an industrial robot, comprising: a plurality of industrial robots, each of which has an operating mechanism and a driving device, wherein the operating mechanism has a tool arranged on the front end side of an arm, and the driving device drives the tool to rotate the tool; and a control device, which receives output signals from a plurality of strain gauges arranged on the driving devices of each of the plurality of industrial robots and controls the plurality of driving devices, wherein when the output signal from at least one of the plurality of strain gauges deviates from a prescribed range, the control device stops the driving of all the operating mechanisms.

[0125] (8) A method for controlling a plurality of industrial robots, wherein the plurality of industrial robots respectively have an operating mechanism and a driving device, wherein the operating mechanism has a tool arranged on the front end side of an arm, and the driving device drives the tool to rotate the tool, wherein when an output signal from at least one of a plurality of strain gauges arranged on the driving device of each of the plurality of industrial robots deviates from a prescribed range, the driving of all the operating mechanisms is stopped.

[0126] The present invention can be utilized, for example, in an industrial robot, a control system for an industrial robot, and a control method for a plurality of industrial robots.

Claims

1. An industrial robot comprising: a working mechanism having a tool disposed on a front end side of an arm; and A driving device, which drives the working mechanism, The driving device comprises: motor; A wave generator, the cross section of which is perpendicular to the central axis is non-circular, and the wave generator can rotate around the central axis together with the rotating part of the motor; an external gear, at least a portion of which is disposed radially outward of the wave generator, the external gear having a plurality of external teeth protruding radially outward; as well as an internal gear, at least a portion of which is disposed radially outward of the external gear, the internal gear extending in an annular shape with the central axis as the center, and having a plurality of internal teeth protruding radially inward and partially meshing with the plurality of external teeth, It is characterized in that The tool is rotatable together with an output portion of either the external gear or the internal gear. A plurality of strain gauges are disposed on at least one of the externally toothed gear and the internally toothed gear.

2. The industrial robot according to claim 1, characterized in that: The plurality of strain gauges are disposed on the external gear.

3. The industrial robot according to claim 1 or 2, characterized in that: The plurality of strain gauges have: a plurality of inner strain gauges, the plurality of inner strain gauges being arranged in a circumferential direction; and a plurality of outer strain gauges arranged in the circumferential direction at positions radially outward of the plurality of inner strain gauges, The plurality of inner strain gauges and the plurality of outer strain gauges form a bridge circuit.

4. The industrial robot according to claim 3, characterized in that: An inner gap region is arranged between the inner strain gauges adjacent to each other in the circumferential direction. The plurality of inner gap regions are arranged at angular intervals of 180° with the central axis as the center. An outer gap region is arranged between the outer strain gauges adjacent to each other in the circumferential direction. The plurality of outer gap regions are arranged at angular intervals of 180° around the central axis, and the inner gap region is adjacent to the outer gap region in a radial direction.

5. The industrial robot according to claim 1 or 2, characterized in that: The plurality of strain gauges have: a plurality of first strain gauges, the plurality of first strain gauges forming a first bridge circuit; and The plurality of second strain gauges are arranged radially outward of the plurality of first strain gauges to form a second bridge circuit.

6. The industrial robot according to claim 5, characterized in that: The industrial robot further includes a control unit that receives output signals from the plurality of first strain gauges and output signals from the plurality of second strain gauges to control the drive device. The control unit stops driving of the working mechanism when the relationship between the output signals from the plurality of first strain gauges and the output signals from the plurality of second strain gauges deviates from a predetermined range.

7. A control system for an industrial robot, comprising: a plurality of industrial robots, each of which has an operating mechanism having a tool disposed on a front end side of an arm and a driving device that drives the tool; and a control device that receives output signals from a plurality of strain gauges disposed on the respective drive devices of the plurality of industrial robots to control the plurality of industrial robots, It is characterized in that The control device stops driving of all the working mechanisms when an output signal from at least one of the plurality of strain gauges deviates from a predetermined range.

8. A control method for a plurality of industrial robots, each of which has an operating mechanism and a driving device, wherein the operating mechanism has a tool disposed on the front end side of an arm, and the driving device drives the tool, characterized in that: When an output signal from at least one of the plurality of strain gauges disposed in the driving device of each of the plurality of industrial robots deviates from a predetermined range, driving of all the working mechanisms is stopped.

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