Control unit, driving device and control method

Abstract

To provide a technology capable of controlling a motor while accurately detecting a state of an arm in a robot arm driving device.SOLUTION: A driving device includes a motor 103, a decelerator 1 and an object. The decelerator decelerates a rotation motion output from the motor. The object is operated by the rotation motion output from the decelerator. A control unit 2 controls the motor on the basis of a detection value of a sensor 50 mounted on the decelerator.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control unit, a drive device, and a control method. [Background technology]

[0002] Conventionally, a drive device including a motor and a reduction gear device that reduces the speed of rotation of the motor is known (for example, Patent Document 1). In the drive device of Patent Document 1, a temperature sensor attached to the motor's encoder corrects the expansion and contraction of the arm due to temperature changes while controlling the motor.

[0003] [Patent Document 1] JP 2015-141583 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in this type of drive device, a reducer is disposed between the motor and the arm, making it difficult for the temperature sensor attached to the motor to accurately detect temperature changes in the arm.

[0005] An object of the present invention is to provide a technique for controlling a motor in a drive device while accurately detecting the state of an arm. [Means for solving the problem]

[0006] The first invention is a control unit of a drive device having a motor, a reducer that decelerates the rotational motion output from the motor, and an object that moves by the rotational motion output from the reducer, which controls the motor based on the detection value of a sensor mounted on the reducer.

[0007] A second invention is a control unit of a drive device having a plurality of motors, a plurality of reducers that decelerate the rotational motion output from each of the plurality of motors, and a plurality of objects that move by the rotational motion output from each of the plurality of reducers, which controls at least one of the plurality of motors based on a detection value of a sensor mounted on at least one of the plurality of reducers.

[0008] A third invention is a control method for a drive device having a motor, a reducer that decelerates the rotational motion output from the motor, and an object that moves by the rotational motion output from the reducer, wherein the motor is controlled based on a detection value of a sensor mounted on the reducer.

[0009] A fourth invention is a control method for a drive device having a plurality of motors, a plurality of reducers that decelerate the rotational motion output from each of the plurality of motors, and a plurality of objects that move by the rotational motion output from each of the plurality of reducers, wherein at least one of the plurality of motors is controlled based on a detection value of a sensor mounted on at least one of the plurality of reducers. Effect of the Invention

[0010] According to the first, second, third and fourth aspects of the present invention, the motor is controlled based on the detection value of the sensor mounted on the reducer, making it possible to control the motor while detecting the state of the arm with high accuracy. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of the drive unit. [Diagram 2] FIG. 2 is a conceptual diagram showing the configuration of a motor, a reducer, an arm, and a control unit. [Diagram 3] FIG. 3 is a vertical cross-sectional view of the reducer. [Figure 4] FIG. 4 is a cross-sectional view of the reducer. [Diagram 5]FIG. 5 is a partial vertical cross-sectional view of the flex gear in the vicinity of the sensor board. [Figure 6] FIG. 6 is a plan view of the sensor substrate. [Figure 7] FIG. 7 is a circuit diagram of the first bridge circuit of the first torque sensor. [Figure 8] FIG. 8 is a circuit diagram of the second bridge circuit of the second torque sensor. [Figure 9] FIG. 9 is a circuit diagram of a third bridge circuit of the angle sensor. [Figure 10] FIG. 10 is a circuit diagram of the fourth bridge circuit of the angle sensor. [Figure 11] FIG. 11 is a graph showing changes over time in the measurement value of the third voltmeter of the third bridge circuit and the measurement value of the fourth voltmeter of the fourth bridge circuit. [Figure 12] FIG. 12 is a circuit diagram of a fifth bridge circuit of the first thrust sensor. [Figure 13] FIG. 13 is a circuit diagram of the sixth bridge circuit of the second thrust sensor. [Figure 14] FIG. 14 is a flowchart showing a flow of control by the control unit. [Figure 15] FIG. 15 is a schematic diagram of a drive device according to a first modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, exemplary embodiments of the present application will be described with reference to the drawings.

[0013] <1. Drive unit configuration> 1 is a schematic diagram of a driving device 100 including a control unit 2 according to one embodiment. The driving device 100 is a so-called industrial robot that performs tasks such as transporting, processing, and assembling parts in, for example, a manufacturing line of industrial products. As shown in FIG. 1, the driving device 100 includes a motor 103, a reducer 1, an arm 102, and a control unit 2. The driving device 100 of this embodiment further includes a base frame 101.

[0014] The arm 102 is rotatably supported with respect to the base frame 101. The motor 103 and the reducer 1 are incorporated in a joint between the base frame 101 and the arm 102. When a driving current is supplied to the motor 103, a rotational motion is output from the motor 103. The reducer 1 reduces the speed of the rotational motion output from the motor 103 and transmits it to the arm 102. As a result, the arm 102 rotates with respect to the base frame 101 at a reduced speed. In other words, the arm 102 is an object that moves due to the rotational motion output from the reducer 1.

[0015] The control unit 2 is a device that controls the operation of the drive device 100. The control unit 2 is configured with a computer or an electric circuit. As shown in Fig. 1, the control unit 2 has a processor 201 such as a CPU, a memory 202 such as a RAM, and a storage unit 203 such as a hard disk drive. A program P for controlling the operation of the drive device 100 is stored in the storage unit 203. The control unit 2 operates according to the program P.

[0016] FIG. 2 is a conceptual diagram showing the configuration of the motor 103, the reducer 1, the arm 102, and the control unit 2. As shown in FIG. 2, the reducer 1 has a sensor 50 capable of detecting the state of the arm 102. The control unit 2 is electrically connected to the sensor 50 and the motor 103. The control unit 2 controls the motor 103 based on a detection value of the sensor 50 mounted on the reducer 1. This allows the motor 103 to be controlled based on the sensor 50 arranged at a position closer to the arm 102 than the motor 103. Therefore, the motor 103 can be controlled while detecting the state of the arm 102 with high accuracy. As a result, the arm 102 can be operated with high accuracy.

[0017] The detailed configuration of the sensor 50 will be described later.

[0018] <2. Configuration of the reducer> Next, the detailed structure of the reducer 1 will be described.

[0019] In the following, a direction parallel to the central axis 9 of the reducer 1 is referred to as the "axial direction", a direction perpendicular to the central axis 9 of the reducer 1 is referred to as the "radial direction", and a direction along an arc centered on the central axis 9 of the reducer 1 is referred to as the "circumferential direction". However, the above "parallel direction" also includes a direction that is approximately parallel. Furthermore, the above "orthogonal direction" also includes a direction that is approximately orthogonal.

[0020] Fig. 3 is a vertical cross-sectional view of the reducer 1 according to one embodiment. Fig. 4 is a horizontal cross-sectional view of the reducer 1 as seen from the position AA in Fig. 2. To avoid complicating the drawing, hatching indicating a cross section is omitted in Fig. 4.

[0021] This reducer 1 is a wave gear reducer. The reducer 1 reduces the rotational motion of a first rotation speed output from a motor 103 to a second rotation speed that is slower than the first rotation speed. As shown in Figures 3 and 4, the reducer 1 includes an input shaft 10, an internal gear 20, a flex gear 30, and a wave generator 40.

[0022] The input shaft 10 is a member that rotates at a first rotational speed before reduction. The input shaft 10 is connected to an output shaft of the motor 103. The input shaft 10 extends in the axial direction along a central axis 9. The input shaft 10 of this embodiment is cylindrical with the central axis 9 as its center. The input shaft 10 passes through the reducer 1 in the axial direction. Note that the input shaft 10 may be the same member as the output shaft of the motor 103.

[0023] The internal gear 20 is a gear that rotates at a second rotational speed slower than the first rotational speed in response to the rotation of the input shaft 10. The internal gear 20 is fixed to the arm 102. The internal gear 20 is disposed radially outside external teeth 32, which will be described later. The rigidity of the internal gear 20 is sufficiently higher than the rigidity of a body portion 31 of the flex gear 30, which will be described later.

[0024] The internal gear 20 is annular about the central axis 9. The internal gear 20 has a plurality of internal teeth 21. The plurality of internal teeth 21 protrude radially inward from the inner circumferential surface of the internal gear 20. The plurality of internal teeth 21 are arranged on the inner circumferential surface of the internal gear 20 at a constant pitch in the circumferential direction.

[0025] The flex gear 30 is a flexibly deformable annular gear. The flex gear 30 is fixed to the base frame 101. As shown in Figures 3 and 4, the flex gear 30 has a body portion 31, a plurality of external teeth 32, a diaphragm portion 33, and a thick portion 34.

[0026] The body portion 31 is a cylindrical portion centered on the central axis 9. One axial end of the body portion 31 is connected to the diaphragm portion 33. The body portion 31 extends from a radially inner end of the diaphragm portion 33 toward the other axial side. The other axial end of the body portion 31 is located radially outside the wave generator 40 and radially inside the internal gear 20. The body portion 31 is flexible and therefore capable of bending and deforming in the radial direction.

[0027] The multiple external teeth 32 protrude radially outward from the radially outer surface of the body 31. The multiple external teeth 32 are arranged on the radially outer surface of the other axial end of the body 31. The multiple external teeth 32 are arranged at a constant pitch in the circumferential direction. Some of the multiple external teeth 32 and some of the multiple internal teeth 21 mesh with each other. The number of internal teeth 21 that the internal gear 20 has and the number of external teeth 32 that the flex gear 30 has are slightly different.

[0028] The diaphragm portion 33 surrounds the central axis 9 and extends in a direction intersecting the central axis 9. The diaphragm portion 33 preferably extends along a plane perpendicular to the central axis 9. The diaphragm portion 33 extends radially outward from one axial end of the body portion 31. The diaphragm portion 33 is annular and surrounds the central axis 9. The diaphragm portion 33 is thin-walled and therefore capable of slight flexural deformation.

[0029] The thick portion 34 is an annular portion located radially outward of the diaphragm portion 33. The axial thickness of the thick portion 34 is greater than the axial thickness of the diaphragm portion 33. The thick portion 34 is fixed to the base frame 101 directly or via another member.

[0030] The wave generator 40 is a mechanism that generates periodic bending deformation in the flex gear 30. The wave generator 40 is disposed radially inside the external teeth 32. The wave generator 40 has a cam 41 and a flexible bearing 42. In this embodiment, the input shaft 10 and the cam 41 are formed as a single part. However, the cam 41 may be a part separate from the input shaft 10. In that case, it is sufficient that the cam 41 is fixed to the input shaft 10. The cam 41 is a part that applies a displacement to the flex gear 30 at a period of 180°. The radial outer surface of the cam 41 is an ellipse centered on the central axis 9.

[0031] The flexible bearing 42 is a bearing that is capable of flexibly deforming. The flexible bearing 42 is disposed between the radially outer surface of the cam 41 and the radially inner surface of the body portion 31 of the flex gear 30.

[0032] The inner ring of the flexible bearing 42 contacts the radially outer surface of the cam 41. The outer ring of the flexible bearing 42 contacts the radially inner surface of the body 31. As a result, the body 31 deforms into an elliptical shape that follows the radially outer surface of the cam 41. As a result, the external teeth 32 of the flex gear 30 mesh with the internal teeth 21 of the internal gear 20 at two locations that correspond to both ends of the major axis of the ellipse. The external teeth 32 do not mesh with the internal teeth 21 at other circumferential positions.

[0033] When the motor 103 is driven, the cam 41 rotates together with the input shaft 10 at a first rotation speed around the central axis 9. As a result, the major axis of the ellipse of the flex gear 30 also rotates at the first rotation speed. Then, the meshing position between the external teeth 32 and the internal teeth 21 also changes in the circumferential direction at the first rotation speed. Also, as described above, the number of the internal teeth 21 of the internal gear 20 and the number of the external teeth 32 of the flex gear 30 are slightly different. Due to this difference in the number of teeth, the meshing position between the external teeth 32 and the internal teeth 21 changes slightly in the circumferential direction for each rotation of the cam 41. As a result, the internal gear 20 rotates relative to the flex gear 30 at a second rotation speed slower than the first rotation speed around the central axis 9.

[0034] <3. About sensors> <3-1.Sensor structure> The reducer 1 has a sensor 50. As shown in Fig. 3, the sensor 50 has a sensor substrate 51. The sensor substrate 51 is fixed to the surface of the diaphragm portion 33.

[0035] Fig. 5 is a partial vertical cross-sectional view of flex gear 30 in the vicinity of sensor substrate 51. Fig. 6 is a plan view of sensor substrate 51. As shown in Fig. 5, sensor substrate 51 has insulating layer 511 and conductor layer 512.

[0036] The insulating layer 511 is flexibly deformable. The insulating layer 511 spreads in a direction intersecting the central axis 9. The insulating layer 511 is annular about the central axis 9. The insulating layer 511 is made of an insulating resin or an inorganic insulating material. The insulating layer 511 is disposed on the surface of the diaphragm portion 33. The conductor layer 512 is formed on the surface of the insulating layer 511. The conductor layer 512 is made of a metal that is a conductor. The conductor layer 512 is made of a material such as a copper alloy, a chromium alloy, or copper.

[0037] The conductor layer 512 includes a torque sensor 60, an angle sensor 70, a thrust sensor 80, and a temperature sensor 90. The torque sensor 60, the angle sensor 70, and the thrust sensor 80 are each configured by a strain gauge. That is, the sensor 50 includes a strain gauge mounted on a gear of the reducer 1. As a result, various sensors can be configured by the strain gauge, as described later. In addition, as shown in FIG. 3, the sensor 50 has a signal processing circuit 52. The signal processing circuit 52 is electrically connected to the torque sensor 60, the angle sensor 70, the thrust sensor 80, and the temperature sensor 90.

[0038] <3-2. Torque sensor> The torque sensor 60 is a sensor for detecting the torque applied to the diaphragm portion 33 of the flex gear 30. In other words, the torque sensor 60 is a sensor whose output signal changes according to the torque applied to the flex gear 30. As shown in Fig. 6, the torque sensor 60 of this embodiment has a first torque sensor 61 and a second torque sensor 62. The second torque sensor 62 is disposed radially outward of the first torque sensor 61.

[0039] The first torque sensor 61 has four strain gauges Ra, Rb, Rc, and Rd. Of the four strain gauges Ra, Rb, Rc, and Rd, two strain gauges Ra and Rb are arranged at intervals in the circumferential direction. The two strain gauges Ra and Rb are each provided in a semicircular arc shape within a range of approximately 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Ra is approximately the same as the radial distance from the central axis 9 to the strain gauge Rb.

[0040] Of the four strain gauges Ra, Rb, Rc, and Rd, the other two strain gauges Rc and Rd are arranged radially outward of the above two strain gauges Ra and Rb. The two strain gauges Rc and Rd are arranged at an interval in the circumferential direction. The two strain gauges Rc and Rd are each provided in a semicircular arc shape within a range of approximately 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Rc is approximately the same as the radial distance from the central axis 9 to the strain gauge Rd.

[0041] Moreover, the two strain gauges Ra, Rc and the two strain gauges Rb, Rd are arranged concentrically and line-symmetrically.

[0042] As shown in Fig. 6, the strain gauges Ra, Rb, Rc, and Rd each have a zigzag pattern extending in the circumferential direction. Each of the strain gauges Ra, Rb, Rc, and Rd has a plurality of resistance wires r1 arranged in the circumferential direction and substantially parallel to each other. Each resistance wire r1 extends in a direction having both radial and circumferential components.

[0043] The resistance wires r1 of the strain gauges Ra and Rd are inclined toward one circumferential side with respect to the radial direction. The resistance wires r1 of the strain gauges Rb and Rc are inclined toward the other circumferential side with respect to the radial direction. The inclination angle of the resistance wires r1 with respect 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 on the radial inside or the radial outside. As a result, the multiple resistance wires r1 are connected in series as a whole.

[0044] The second torque sensor 62 has four strain gauges Re, Rf, Rg, and Rh. Of the four strain gauges Re, Rf, Rg, and Rh, two strain gauges Re and Rf are arranged at intervals in the circumferential direction. The two strain gauges Re and Rf are each provided in a semicircular arc shape within a range of approximately 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.

[0045] Of the four strain gauges Re, Rf, Rg, and Rh, the other two strain gauges Rg and Rh are arranged radially outward of the above two strain gauges Re and Rf. The two strain gauges Rg and Rh are arranged at an interval in the circumferential direction. The two strain gauges Rg and Rh are each provided in a semicircular arc shape within a range of approximately 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Rg is approximately the same as the radial distance from the central axis 9 to the strain gauge Rh.

[0046] Moreover, the two strain gauges Re, Rg and the two strain gauges Rf, Rh are arranged concentrically and line-symmetrically.

[0047] As shown in Fig. 6, the strain gauges Re, Rf, Rg, and Rh each have a zigzag pattern extending in the circumferential direction. Each of the strain gauges Re, Rf, Rg, and Rh has a plurality of resistance wires r2 arranged in the circumferential direction and substantially parallel to each other. Each resistance wire r2 extends in a direction having both radial and circumferential components.

[0048] The resistance wires r2 of the strain gauges Re and Rh are inclined toward one circumferential side with respect to the radial direction. The resistance wires r2 of the strain gauges Rf and Rg are inclined toward the other circumferential side with respect to the radial direction. The inclination angle of the resistance wires r2 with respect to the radial direction is, for example, 45°. The ends of the resistance wires r2 adjacent in the circumferential direction are alternately connected on the radial inside or the radial outside. As a result, the multiple resistance wires r2 are connected in series as a whole.

[0049] Fig. 7 is a circuit diagram of a first bridge circuit C1 including four strain gauges Ra, Rb, Rc, and Rd of the first torque sensor 61. As shown in Fig. 7, the four strain gauges Ra, Rb, Rc, and Rd are connected to each other to form the first bridge circuit C1.

[0050] The strain gauges Ra and Rb are connected in series in this order. The strain gauges Rc and Rd are connected in series in this order. Then, between the positive and negative poles of the power supply voltage, a row of two strain gauges Ra, Rb and a row of two strain gauges Rc, Rd are connected in parallel. In addition, a first voltmeter V1 is connected between a midpoint M11 of the two strain gauges Ra, Rb and a midpoint M12 of the two strain gauges Rc, Rd.

[0051] The resistance value of each resistance wire r1 changes according to the torque applied to the area in which the resistance wire r1 is disposed. For example, when a torque is applied to the diaphragm portion 33 in one circumferential direction around the central axis 9, the resistance value of each resistance wire r1 of the two strain gauges Ra, Rd increases, and the resistance value of each resistance wire r1 of the other two strain gauges Rb, Rc decreases. On the other hand, when a torque is applied to the diaphragm portion 33 in the other circumferential direction around the central axis 9, the resistance value of each resistance wire r1 of the two strain gauges Ra, Rd decreases, and the resistance value of each resistance wire r1 of the other two strain gauges Rb, Rc increases. In this way, the two strain gauges Ra, Rd and the other two strain gauges Rb, Rc show resistance value changes in opposite directions with respect to torque.

[0052] When the resistance values ​​of the four strain gauges Ra, Rb, Rc, and Rd change, the potential difference between the midpoint M11 of the two strain gauges Ra, Rb and the midpoint M12 of the two strain gauges Rc, Rd changes, and the measurement value of the first voltmeter V1 also changes. The signal processing circuit 52 detects the direction and magnitude of the torque applied to the diaphragm portion 33 based on the measurement value of the first voltmeter V1.

[0053] Fig. 8 is a circuit diagram of a second bridge circuit C2 including four strain gauges Re, Rf, Rg, and Rh of the second torque sensor 62. As shown in Fig. 8, the four strain gauges Re, Rf, Rg, and Rh are connected to each other to form the second bridge circuit C2.

[0054] The strain gauges Re and Rf are connected in series in this order. The strain gauges Rg and Rh are connected in series in this order. Then, between the positive and negative poles of the power supply voltage, a row of two strain gauges Re, Rf and a row of two strain gauges Rg, Rh are connected in parallel. In addition, a second voltmeter V2 is connected between a midpoint M21 of the two strain gauges Re, Rf and a midpoint M22 of the two strain gauges Rg, Rh.

[0055] The resistance value of each resistance wire r2 changes according to the torque applied to the area in which the resistance wire r2 is disposed. For example, when a torque is applied to the diaphragm portion 33 in one circumferential direction around the central axis 9, the resistance value of each resistance wire r2 of the two strain gauges Re, Rh increases, and the resistance value of each resistance wire r2 of the other two strain gauges Rf, Rg decreases. On the other hand, when a torque is applied to the diaphragm portion 33 in the other circumferential direction around the central axis 9, the resistance value of each resistance wire r2 of the two strain gauges Re, Rh decreases, and the resistance value of each resistance wire r2 of the other two strain gauges Rf, Rg increases. In this way, the two strain gauges Re, Rh and the other two strain gauges Rf, Rg show resistance value changes in opposite directions with respect to torque.

[0056] When the resistance values ​​of the four strain gauges Re, Rf, Rg, and Rh change, the potential difference between the midpoint M21 of the two strain gauges Re and Rf and the midpoint M22 of the two strain gauges Rg and Rh changes, and the measurement value of the second voltmeter V2 also changes. The signal processing circuit 52 detects the direction and magnitude of the torque applied to the diaphragm portion 33 based on the measurement value of the second voltmeter V2.

[0057] Moreover, the reducer 1 of this embodiment has two torque sensors 61, 62. The signal processing circuit 52 uses one of the output signals of the two torque sensors 61, 62 as the output signal of the torque sensor 60. By having the two torque sensors 61, 62, even if an abnormality occurs in one of the torque sensors, the torque can be detected by the other torque sensor. Furthermore, if an abnormality occurs in one of the torque sensors, the abnormality can be detected.

[0058] <3-3.Angle sensor> The angle sensor 70 is a sensor for detecting the rotation angle of the rotational motion input to the reducer 1. As shown in Fig. 6, the angle sensor 70 has eight strain gauges Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp. The eight strain gauges Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp are arranged at intervals in the circumferential direction.

[0059] Each of the eight strain gauges Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp is formed by one conducting wire. Each of the strain gauges Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp has a resistance wire extending in an arc shape along the circumferential direction. However, in each of the strain gauges Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp, the resistance wire extending in the circumferential direction may be repeatedly arranged in the radial direction. Also, the resistance wire of each of the strain gauges Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp may extend in the radial direction. Also, in each of the strain gauges Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp, the resistance wire extending in the radial direction may be repeatedly arranged in the circumferential direction.

[0060] Of the eight strain gauges Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp, the four strain gauges Ri, Rk, Rm, and Ro that are not adjacent to each other are connected to each other to form a third bridge circuit C3. FIG. 9 is a circuit diagram of the third bridge circuit C3. As shown in FIG. 9, the strain gauge Ri and the strain gauge Rk are connected in series in this order. The strain gauge Ro and the strain gauge Rm are connected in series in this order. Then, between the positive and negative poles of the power supply voltage, a row of two strain gauges Ri and Rk and a row of two strain gauges Ro and Rm are connected in parallel. In addition, a third voltmeter V3 is connected between a midpoint M31 of the two strain gauges Ri and Rk and a midpoint M32 of the two strain gauges Ro and Rm.

[0061] Of the eight strain gauges Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp, the remaining four strain gauges Rj, Rl, Rn, and Rp are connected to each other to form a fourth bridge circuit C4. FIG. 10 is a circuit diagram of the fourth bridge circuit C4. As shown in FIG. 10, the strain gauges Rp and Rn are connected in series in this order. The strain gauges Rj and Rl are connected in series in this order. Then, between the positive and negative poles of the power supply voltage, a row of two strain gauges Rp and Rn and a row of two strain gauges Rj and Rl are connected in parallel. In addition, a fourth voltmeter V4 is connected between a midpoint M41 of the two strain gauges Rp and Rn and a midpoint M42 of the two strain gauges Rj and Rl.

[0062] When the reducer 1 is driven, a portion that expands in the circumferential direction (hereinafter referred to as an "expanded portion") and a portion that contracts in the circumferential direction (hereinafter referred to as a "contracted portion") are generated in the diaphragm portion 33 of the flex gear 30. Specifically, two expanded portions and two contracted portions are generated alternately in the circumferential direction. That is, the expanded portions and contracted portions are generated alternately at intervals of 90° in the circumferential direction around the central axis 9. The locations where these expanded portions and contracted portions are generated rotate at the first rotation speed described above.

[0063] The resistance value of each of the eight strain gauges Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp changes according to the circumferential expansion and contraction of the diaphragm portion 33. For example, when the above-mentioned expansion portion overlaps with a certain strain gauge, the resistance value of that strain gauge increases. Also, when the above-mentioned contraction portion overlaps with a certain strain gauge, the resistance value of that strain gauge decreases.

[0064] In the example of Fig. 6, when the contraction portion overlaps with the strain gauges Ri, Rm, the expansion portion overlaps with the strain gauges Rk, Ro. Also, when the expansion portion overlaps with the strain gauges Ri, Rm, the contraction portion overlaps with the strain gauges Rk, Ro. Therefore, in the third bridge circuit C3, the strain gauges Ri, Rm and the strain gauges Rk, Ro show resistance value changes in opposite directions.

[0065] 6, when the contraction portion overlaps with the strain gauges Rp, Rl, the expansion portion overlaps with the strain gauges Rn, Rj. When the expansion portion overlaps with the strain gauges Rp, Rl, the contraction portion overlaps with the strain gauges Rn, Rj. Therefore, in the fourth bridge circuit C4, the strain gauges Rp, Rl and the strain gauges Rn, Rj show opposite resistance value changes.

[0066] Fig. 11 is a graph showing the change over time in the measurement value v3 of the third voltmeter V3 of the third bridge circuit C3 and the measurement value v4 of the fourth voltmeter V4 of the fourth bridge circuit C4. The horizontal axis of the graph in Fig. 11 indicates time. The vertical axis of the graph in Fig. 11 indicates voltage value. When the reducer 1 is driven, as shown in Fig. 11, the third voltmeter V3 and the fourth voltmeter V4 each output measurement values ​​v3 and v4 that have a periodically changing sine wave shape. The period T of the measurement values ​​v3 and v4 corresponds to 1 / 2 the period of the first rotation speed described above. In addition, the direction of the input rotational motion can be determined based on whether the phase of the measurement value v4 of the fourth voltmeter V4 leads the phase of the measurement value v3 of the third voltmeter V3 by 1 / 8 period of the first rotation speed (1 / 4 period of the measurement values ​​v3 and v4) or lags behind the phase of the measurement value v3 of the third voltmeter V3 by 1 / 8 period of the first rotation speed (1 / 4 period of the measurement values ​​v3 and v4).

[0067] The signal processing circuit 52 detects the rotation angle of the rotary motion input to the reducer 1 based on the measurement value v3 of the third voltmeter V3 and the measurement value v4 of the fourth voltmeter V4. Specifically, the signal processing circuit 52 stores a function table that associates combinations of the measurement value v3 of the third voltmeter V3 and the measurement value v4 of the fourth voltmeter V4 with the rotation angle. The signal processing circuit 52 inputs the measurement values ​​v3 and v4 into the function table, thereby outputting the rotation angle.

[0068] When the reducer 1 is driven, periodic flexural deformation occurs in the flex gear 30. For this reason, the output signal of the first torque sensor 61 and the output signal of the second torque sensor 62 described above contain a component reflecting the torque that is originally to be measured, and an error component (ripple error) caused by the periodic flexural deformation of the flex gear 30. The ripple error changes in a sinusoidal shape according to the rotation angle of the rotary motion input to the reducer 1.

[0069] Therefore, the signal processing circuit 52 calculates the above-mentioned ripple error according to the rotation angle detected by the angle sensor 70. Then, the output signals of the first torque sensor 61 and the second torque sensor 62 are corrected using the calculated ripple error. Specifically, the signal processing circuit 52 increases or decreases the output signals of the first torque sensor 61 and the second torque sensor 62 in a direction that cancels the ripple error. As a result, the signal processing circuit 52 can output the torque applied to the flex gear 30 with higher accuracy.

[0070] Alternatively, the signal processing circuit 52 may multiply the measurement values ​​v3 and v4 of the third voltmeter V3 and the fourth voltmeter V4 by a predetermined coefficient and combine the results with the output signals of the first torque sensor 61 and the second torque sensor 62, without calculating the rotation angle described above. In this way, the processing load for calculating the rotation angle can be reduced. Therefore, the calculation speed of the signal processing circuit 52 can be improved.

[0071] <3-4. Thrust sensor> The thrust sensor 80 is a sensor for detecting the thrust force applied to the flex gear 30. That is, the thrust sensor 80 is a sensor whose output signal changes according to the thrust force applied to the flex gear 30. The thrust force is a force in the axial direction. As shown in FIG. 6, the thrust sensor 80 of this embodiment has a first thrust sensor 81 and a second thrust sensor 82.

[0072] The first thrust sensor 81 has four strain gauges Rq, Rr, Rs, and Rt. Of the four strain gauges Rq, Rr, Rs, and Rt, two strain gauges Rq and Rr are disposed radially outside the torque sensor 60. That is, the two strain gauges Rq and Rr are preferably disposed at the radially outer end of the diaphragm portion 33. The two strain gauges Rq and Rr are disposed at intervals in the circumferential direction. The two strain gauges Rq and Rr are each provided in a semicircular arc shape within a range of approximately 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Rq is approximately the same as the radial distance from the central axis 9 to the strain gauge Rr.

[0073] Of the four strain gauges Rq, Rr, Rs, and Rt, the other two strain gauges Rs and Rt are disposed radially inside the torque sensor 60. In other words, the two strain gauges Rs and Rt are preferably disposed at the radially inner end of the diaphragm portion 33. The two strain gauges Rs and Rt are also disposed at a distance in the circumferential direction. The two strain gauges Rs and Rt are each provided in a semicircular arc shape within a range of approximately 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Rs is approximately the same as the radial distance from the central axis 9 to the strain gauge Rt.

[0074] That is, the two strain gauges Rq, Rr and the two strain gauges Rs, Rt are arranged at an interval in the radial direction.

[0075] As shown in FIG. 6, the strain gauges Rq, Rr, Rs, and Rt each have a pattern that extends in the circumferential direction while winding in a zigzag pattern. Each of the strain gauges Rq, Rr, Rs, and Rt has a plurality of resistance wires r3 arranged in the circumferential direction and substantially parallel to each other. Each resistance wire r3 extends in the radial direction. The ends of the resistance wires r3 adjacent in the circumferential direction are alternately connected on the radial inside or the radial outside. As a result, the plurality of resistance wires r3 are connected in series as a whole.

[0076] The second thrust sensor 82 has four strain gauges Ru, Rv, Rw, and Rx. Of the four strain gauges Ru, Rv, Rw, and Rx, the two strain gauges Ru and Rv are disposed radially outside the above-mentioned strain gauges Rq and Rr. The two strain gauges Ru and Rv are disposed at an interval in the circumferential direction. The two strain gauges Ru and Rv are each provided in a semicircular arc shape within a range of approximately 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Ru is approximately the same as the radial distance from the central axis 9 to the strain gauge Rv.

[0077] Of the four strain gauges Ru, Rv, Rw, and Rx, the other two strain gauges Rw and Rx are arranged radially inward of the above-mentioned strain gauges Rs and Rt. The two strain gauges Rw and Rx are arranged at an interval in the circumferential direction. The two strain gauges Rw and Rx are each provided in a semicircular arc shape within a range of approximately 180° centered on the central axis 9. The radial distance from the central axis 9 to the strain gauge Rw is approximately the same as the radial distance from the central axis 9 to the strain gauge Rx.

[0078] That is, the two strain gauges Ru, Rv and the two strain gauges Rw, Rx are arranged at an interval in the radial direction.

[0079] As shown in FIG. 6, the strain gauges Ru, Rv, Rw, and Rx each have a pattern that extends in the circumferential direction while winding in a zigzag pattern. Each of the strain gauges Ru, Rv, Rw, and Rx has a plurality of resistance wires r4 arranged in the circumferential direction and substantially parallel to each other. Each resistance wire r4 extends in the radial direction. The ends of the resistance wires r4 adjacent in the circumferential direction are alternately connected on the radial inside or the radial outside. As a result, the plurality of resistance wires r4 are connected in series as a whole.

[0080] Fig. 12 is a circuit diagram of a fifth bridge circuit C5 including four strain gauges Rq, Rr, Rs, and Rt of the first thrust sensor 81. As shown in Fig. 12, the four strain gauges Rq, Rr, Rs, and Rt are connected to each other to form the fifth bridge circuit C5.

[0081] The strain gauges Rq and Rs are connected in series in this order. The strain gauges Rt and Rr are connected in series in this order. Then, between the positive and negative poles of the power supply voltage, a row of two strain gauges Rq, Rs and a row of two strain gauges Rt, Rr are connected in parallel. In addition, a fifth voltmeter V5 is connected between a midpoint M51 of the two strain gauges Rq, Rs and a midpoint M52 of the two strain gauges Rt, Rr.

[0082] The resistance wires r3 included in the four strain gauges Rq, Rr, Rs, and Rt of the first thrust sensor 81 all extend in the radial direction. Therefore, the change in the resistance value of the strain gauges Rq, Rr, Rs, and Rt due to the torque in the circumferential direction is extremely small. However, when the diaphragm portion 33 of the flex gear 30 is displaced in the axial direction, the resistance value of the strain gauges Rq, Rr, Rs, and Rt changes.

[0083] Specifically, when the radially inner end of the diaphragm portion 33 is displaced in a direction toward the internal gear 20, the resistance value of the two outer strain gauges Rq and Rr among the four strain gauges Rq, Rr, Rs, and Rt increases, and the resistance value of the two inner strain gauges Rs and Rt decreases. On the other hand, when the radially inner end of the diaphragm portion 33 is displaced in a direction away from the internal gear 20, the resistance value of the two outer strain gauges Rq and Rr among the four strain gauges Rq, Rr, Rs, and Rt decreases, and the resistance value of the two inner strain gauges Rs and Rt increases. In this way, the two outer strain gauges Rq and Rr and the two inner strain gauges Rs and Rt show resistance value changes in opposite directions to each other with respect to the axial displacement of the diaphragm portion 33.

[0084] When the resistance values ​​of the four strain gauges Rq, Rr, Rs, and Rt change, the potential difference between the midpoint M51 of the two strain gauges Rq, Rs and the midpoint M52 of the two strain gauges Rt, Rr changes, and the measurement value of the fifth voltmeter V5 also changes. The signal processing circuit 52 detects the direction and magnitude of the thrust force acting on the flex gear 30 based on the measurement value of the fifth voltmeter V5.

[0085] Fig. 13 is a circuit diagram of a sixth bridge circuit C6 including four strain gauges Ru, Rv, Rw, and Rx of the second thrust sensor 82. As shown in Fig. 13, the four strain gauges Ru, Rv, Rw, and Rx are connected to each other to form the sixth bridge circuit C6.

[0086] The strain gauges Ru and Rw are connected in series in this order. The strain gauges Rx and Rv are connected in series in this order. Then, between the positive and negative poles of the power supply voltage, a row of two strain gauges Ru, Rw and a row of two strain gauges Rx, Rv are connected in parallel. In addition, a sixth voltmeter V6 is connected between a midpoint M61 of the two strain gauges Ru, Rw and a midpoint M62 of the two strain gauges Rx, Rv.

[0087] The resistance wires r4 included in the four strain gauges Ru, Rv, Rw, and Rx of the second thrust sensor 82 all extend in the radial direction. Therefore, the change in the resistance value of the strain gauges Ru, Rv, Rw, and Rx due to the torque in the circumferential direction is extremely small. However, when the diaphragm portion 33 of the flex gear 30 is displaced in the axial direction, the resistance value of the strain gauges Ru, Rv, Rw, and Rx changes.

[0088] Specifically, when the radially inner end of the diaphragm portion 33 is displaced in a direction toward the internal gear 20, the resistance value of the two outer strain gauges Ru and Rv of the four strain gauges Ru, Rv, Rw, and Rx increases, and the resistance value of the two inner strain gauges Rw and Rx decreases. On the other hand, when the radially inner end of the diaphragm portion 33 is displaced in a direction away from the internal gear 20, the resistance value of the two outer strain gauges Ru and Rv of the four strain gauges Ru, Rv, Rw, and Rx decreases, and the resistance value of the two inner strain gauges Rw and Rx increases. In this way, the two outer strain gauges Ru and Rv and the two inner strain gauges Rw and Rx show resistance value changes in opposite directions to each other with respect to the axial displacement of the diaphragm portion 33.

[0089] When the resistance values ​​of the four strain gauges Ru, Rv, Rw, and Rx change, the potential difference between the midpoint M61 of the two strain gauges Ru, Rw and the midpoint M62 of the two strain gauges Rx, Rv changes, and the measurement value of the sixth voltmeter V6 also changes. The signal processing circuit 52 detects the direction and magnitude of the thrust force acting on the flex gear 30 based on the measurement value of the sixth voltmeter V6.

[0090] Furthermore, signal processing circuit 52 corrects the output signals of first torque sensor 61 and second torque sensor 62 in accordance with the thrust force detected by one of the two thrust sensors 81, 82. Specifically, the output signals of first torque sensor 61 and second torque sensor 62 are increased or decreased in a direction that cancels the effect of the axial displacement of diaphragm portion 33. This allows signal processing circuit 52 to output the torque applied to flex gear 30 with greater accuracy.

[0091] Moreover, the reducer 1 of this embodiment has two thrust sensors 81, 82. The signal processing circuit 52 uses one of the output signals of the two thrust sensors 81, 82 as the output signal of the thrust sensor 80. By having the two thrust sensors 81, 82, even if an abnormality occurs in one of the thrust sensors, the thrust force can be detected by the other thrust sensor. Furthermore, if an abnormality occurs in one of the thrust sensors, the abnormality can be detected.

[0092] <3-5. Temperature sensor> The temperature sensor 90 is a sensor that detects the temperature of the flex gear 30. In other words, the temperature sensor 90 is a sensor whose output signal changes depending on the temperature of the flex gear 30. As shown in FIG 6, the temperature sensor 90 of this embodiment has a first temperature sensor 91 and a second temperature sensor 92.

[0093] The first temperature sensor 91 has one resistance wire r5. The resistance wire r5 is disposed radially inward from the torque sensor 60. The resistance wire r5 is disposed in an arc shape in a range of about 360° centered on the central axis 9. Therefore, even if the diaphragm portion 33 is displaced in the circumferential direction, the radial direction, or the axial direction, the resistance value of the resistance wire r5 hardly changes. Therefore, the resistance value of the resistance wire r5 is predominantly changed by temperature. The signal processing circuit 52 measures the resistance value of the resistance wire r5 based on an output signal from a bridge circuit formed by the resistance wire r5 and a fixed resistor. Then, the signal processing circuit 52 detects the temperature of the flex gear 30 based on the measured resistance value.

[0094] The second temperature sensor 92 has one resistance wire r6. The resistance wire r6 is disposed radially outward from the torque sensor 60. The resistance wire r6 is disposed in an arc shape in a range of approximately 360° centered on the central axis 9. Therefore, even if the diaphragm portion 33 is displaced in the circumferential direction, the radial direction, or the axial direction, the resistance value of the resistance wire r6 hardly changes. Therefore, the resistance value of the resistance wire r6 is dominated by changes due to temperature. The signal processing circuit 52 measures the resistance value of the resistance wire r6 based on an output signal from a bridge circuit formed by the resistance wire r6 and a fixed resistor. Then, the signal processing circuit 52 detects the temperature of the flex gear 30 based on the measured resistance value.

[0095] Furthermore, the signal processing circuit 52 corrects the output signals of the first torque sensor 61 and the second torque sensor 62 in accordance with the temperature detected by one of the two temperature sensors 91, 92. Specifically, the output signals of the first torque sensor 61 and the second torque sensor 62 are increased or decreased in a direction that cancels the influence of temperature. This allows the signal processing circuit 52 to output the torque applied to the flex gear 30 with greater accuracy.

[0096] Moreover, the reducer 1 of this embodiment has two temperature sensors 91, 92. The signal processing circuit 52 uses one of the output signals of the two temperature sensors 91, 92 as the output signal of the temperature sensor 90. By having the two temperature sensors 91, 92, even if an abnormality occurs in one of the temperature sensors, the temperature of the flex gear 30 can be detected by the other temperature sensor. Furthermore, if an abnormality occurs in one of the temperature sensors, the abnormality can be detected.

[0097] <4. Control by the control unit> The control unit 2 controls the motor 103 based on the detection value of the above-mentioned sensor 50. Fig. 14 is a flowchart showing the flow of the control by the control unit 2.

[0098] The control unit 2 determines whether the difference between the output signals of the two sensors is equal to or greater than a predetermined threshold (step S1). Specifically, the control unit 2 determines whether the difference between the output signals of the two temperature sensors 91, 92 is equal to or greater than a first threshold previously stored in the storage unit 203. The control unit 2 also determines whether the difference between the output signals of the two torque sensors 61, 62 is equal to or greater than a second threshold previously stored in the storage unit 203. The control unit 2 also determines whether the difference between the output signals of the two thrust sensors 81, 82 is equal to or greater than a third threshold previously stored in the storage unit 203.

[0099] Then, when the difference between the output signals of the two sensors becomes equal to or greater than the threshold value (step S1: Yes), the control unit 2 performs alert control (step S2). The alert control is, for example, output of an alert. Output of an alert may be displaying an alert on a display, turning on a warning lamp, or sounding a warning sound. The alert control may also be a case in which the control unit 2 stops or limits the operation of the drive device 100. The alert control may also be a case in which the operation of the drive device 100 is controlled without issuing information that can be perceived by humans.

[0100] Specifically, the control unit 2 performs alert control when the difference between the output signals of the two temperature sensors 91, 92 becomes equal to or greater than a first threshold value. In addition, the control unit 2 performs alert control when the difference between the output signals of the two torque sensors 61, 62 becomes equal to or greater than a second threshold value. In addition, the control unit 2 performs alert control when the difference between the output signals of the two thrust sensors 81, 82 becomes equal to or greater than a third threshold value.

[0101] When the difference between the output signals of the two sensors is equal to or greater than the threshold value, there is a possibility that one of the two sensors is malfunctioning. For this reason, the control unit 2 performs the above-mentioned alert control. This allows the user of the drive device 100 to check for the presence or absence of a malfunction and to respond to the malfunction. In some cases, the operation of the drive device 100 may be controlled without the user having to check for an abnormality in the drive device 100.

[0102] In step S1, if the difference between the output signals of the two sensors is not equal to or greater than the threshold value (step S1: No), the control unit 2 next determines whether or not the value of the output signal of the sensor 50 is outside a predetermined allowable range (step S3). Specifically, the control unit 2 determines whether or not the value of the output signal of the temperature sensor 90 is outside a first allowable range previously stored in the storage unit 203. The control unit 2 also determines whether or not the value of the output signal of the torque sensor 60 is outside a second allowable range previously stored in the storage unit 203. The control unit 2 also determines whether or not the value of the output signal of the thrust sensor 80 is outside a third allowable range previously stored in the storage unit 203.

[0103] Then, if the value of the output signal of the sensor 50 is outside the above-mentioned allowable range (step S3: Yes), the control unit 2 performs alert control (step S4). The alert control is, for example, output of an alert. Output of an alert may be displaying an alert on a display, turning on a warning lamp, or sounding a warning sound. The alert control may also be a case in which the control unit 2 stops or limits the operation of the drive device 100. The alert control may also be a case in which the operation of the drive device 100 is controlled without issuing information that can be perceived by humans.

[0104] Specifically, the control unit 2 performs alert control when the value of the output signal of the temperature sensor 90 falls outside a first allowable range. The control unit 2 also performs alert control when the value of the output signal of the torque sensor 60 falls outside a second allowable range. The control unit 2 also performs alert control when the value of the output signal of the thrust sensor 80 falls outside a third allowable range.

[0105] When the value of the output signal of the temperature sensor 90 falls outside the first allowable range, it indicates that the temperature of the flex gear 30 is not normal. When the value of the output signal of the torque sensor 60 falls outside the second allowable range, it indicates that the torque applied to the flex gear 30 is not normal. When the value of the output signal of the thrust sensor 80 falls outside the third allowable range, it indicates that the thrust force applied to the flex gear 30 is not normal. For this reason, the control unit 2 performs the above-mentioned alert control. This allows the user of the drive device 100 to deal with the situation. In some cases, the operation of the drive device 100 may be controlled without the user having to check for an abnormality in the drive device 100.

[0106] In step S3, if the value of the output signal of the sensor 50 is not outside the allowable range (step S3: No), the control unit 2 controls the motor 103 based on the output signal of the sensor 50 (step S5).

[0107] Specifically, the control unit 2 controls the motor 103 based on the detection signal of the temperature sensor 90. The detection signal of the temperature sensor 90 is correlated with the amount of expansion or contraction of the arm 102 due to a change in temperature. In particular, the temperature sensor 90 is disposed at a position closer to the arm 102 than the motor 103. Therefore, the detection signal of the temperature sensor 90 is a signal that accurately reflects the amount of expansion or contraction of the arm 102. Therefore, by controlling the motor 103 based on the detection signal of the temperature sensor 90, it is possible to perform accurate control that takes into account the amount of expansion or contraction of the arm 102 due to a change in temperature.

[0108] Furthermore, the control unit 2 controls the motor 103 based on the detection signal of the torque sensor 60. The detection signal of the torque sensor 60 reflects the torque acting on the flex gear 30 due to the swing of the arm 102 in the rotational direction. In particular, the torque sensor 60 is disposed at a position closer to the arm 102 than the motor 103. Therefore, the detection signal of the torque sensor 60 is a signal that accurately reflects the swing of the arm 102 in the rotational direction. Therefore, by controlling the motor 103 based on the detection signal of the torque sensor 60, it is possible to perform control that takes into account the swing of the arm 102 in the rotational direction with high accuracy.

[0109] Moreover, the sensor 50 of this embodiment is affixed to the flex gear 30 of the reducer 1. The sensor 50 can be used to detect the state of the reducer 1 itself, and can also be used to detect the state of the arm 102 as described above. Therefore, it is not necessary to provide a sensor for detecting the state of the reducer 1 itself and a sensor for detecting the state of the arm 102 separately. This makes it possible to reduce the number of sensors mounted on the driving device 100. Also, the configuration when mounting sensors on the driving device 100 can be simplified.

[0110] <5. Modifications> Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. Various modifications will be described below, focusing on the differences from the above embodiment.

[0111] <5-1. First modified example> Fig. 15 is a schematic diagram of a driving device 100 according to a first modified example. As shown in Fig. 15, the driving device 100 may have a plurality of motors, a plurality of reducers that reduce the speed of the rotational motion output from each of the plurality of motors, and a plurality of objects that operate by the rotational motion output from each of the plurality of reducers. In the example of Fig. 15, the driving device 100 has two motors 103A and 103B, two reducers 1A and 1B that reduce the speed of the rotational motion output from each of the two motors 103A and 103B, and two arms 102A and 102B that operate by the rotational motion output from each of the two reducers 1A and 1B.

[0112] The arm 102A is rotatably supported with respect to the base frame 101. The motor 103A and the reducer 1A are incorporated in a first joint between the base frame 101 and the arm 102A. When a driving current is supplied to the motor 103A, a rotational motion is output from the motor 103A. The reducer 1A reduces the speed of the rotational motion output from the motor 103A and transmits it to the arm 102A. As a result, the arm 102A rotates with respect to the base frame 101 at a reduced speed. That is, the arm 102A is an object that moves due to the rotational motion output from the reducer 1A.

[0113] The arm 102B is supported rotatably relative to the arm 102A. The motor 103B and the reducer 1B are incorporated in a second joint between the arm 102A and the arm 102B. When a driving current is supplied to the motor 103B, a rotational motion is output from the motor 103B. The reducer 1B reduces the speed of the rotational motion output from the motor 103B and transmits it to the arm 102B. As a result, the arm 102B rotates relative to the arm 102A at a reduced speed. That is, the arm 102B is an object that moves due to the rotational motion output from the reducer 1B.

[0114] In this case, the control unit 2 may control the motor 103A of the first joint based on the detection value of the sensor 50 mounted on the reducer 1B of the second joint. In this way, the motor 103A of the first joint can be controlled taking into consideration the swing in the rotational direction, the vibration in the axial direction, and the amount of expansion or contraction of the arm 102B, which is the object located at the most distal end. This allows the position of the distal end of the arm 102B to be controlled with greater precision.

[0115] In addition, the control unit 2 may control the motor 103A of the first joint based on the detection values ​​of both the sensor 50 mounted on the reducer 1A of the first joint and the sensor 50 mounted on the reducer 1B of the second joint.

[0116] In this way, the control unit 2 may control at least one motor 103 of the multiple motors 103 based on the detection value of the sensor 50 mounted on at least one of the multiple reducers 1.

[0117] <5-2. Other variations> In the above embodiment, one drive device 100 has one control unit 2. However, the control unit 2 may be a system that controls a plurality of drive devices 100 in an integrated manner.

[0118] In the above embodiment, the sensor 50 includes the torque sensor 60, the angle sensor 70, the thrust sensor 80, and the temperature sensor 90. However, the sensor 50 may include only some of the torque sensor 60, the angle sensor 70, the thrust sensor 80, and the temperature sensor 90.

[0119] In the above embodiment, the torque sensor 60 includes the first torque sensor 61 and the second torque sensor 62. However, the torque sensor 60 may include only one of the first torque sensor 61 and the second torque sensor 62.

[0120] In the above embodiment, the thrust sensor 80 includes the first thrust sensor 81 and the second thrust sensor 82. However, the thrust sensor 80 may include only one of the first thrust sensor 81 and the second thrust sensor 82.

[0121] In the above embodiment, the temperature sensor 90 includes the first temperature sensor 91 and the second temperature sensor 92. However, the temperature sensor 90 may include only one of the first temperature sensor 91 and the second temperature sensor 92.

[0122] In the above embodiment, the sensor 50 is attached to the flex gear 30. However, the sensor 50 may be attached to the internal gear 20 instead of the flex gear 30.

[0123] In the reducer 1 of the above embodiment, the flex gear 30 is fixed to the base frame 101, and the internal gear 20 rotates at the second rotation speed after deceleration. However, the internal gear 20 may be fixed to the base frame 101, and the flex gear 30 may rotate at the second rotation speed after deceleration.

[0124] The flex gear 30 in the above embodiment is a so-called "hat-shaped" gear in which the diaphragm portion 33 spreads outward in the radial direction from the body portion 31. However, the flex gear 30 may be a so-called "cup-shaped" gear in which the diaphragm portion 33 spreads inward in the radial direction from the body portion 31.

[0125] In the above embodiment, the driving device 100 is an industrial robot having an arm. However, the driving device 100 may be another device such as an assist suit or an unmanned transport vehicle.

[0126] In addition, the detailed configurations of the motor, the reducer, the drive device, and the control unit may be appropriately modified without departing from the spirit of the present invention. Furthermore, the elements appearing in the above-described embodiment and modified examples may be appropriately combined without causing any contradiction.

[0127] <6. Summary> The present technology can have the following configurations.

[0128] (1) A control unit of a drive device having a motor, a reducer that decelerates the rotational motion output from the motor, and an object that moves by the rotational motion output from the reducer, the control unit controlling the motor based on the detection value of a sensor mounted on the reducer.

[0129] (2) A control unit of a drive device having a plurality of motors, a plurality of reducers that reduce the rotational motion output from each of the plurality of motors, and a plurality of objects that move by the rotational motion output from each of the plurality of reducers, the control unit controlling at least one of the plurality of motors based on a detection value of a sensor mounted on at least one of the plurality of reducers.

[0130] (3) A control unit according to (1) or (2), wherein the sensor includes a strain gauge mounted on a gear of the reducer.

[0131] (4) A control unit according to any one of (1) to (3), wherein the sensor is a temperature sensor whose output signal changes depending on the temperature of the gear.

[0132] (5) A control unit as described in (4), wherein the reducer has two of the temperature sensors, and the control unit performs alert control when the difference in output signals of the two temperature sensors becomes equal to or greater than a predetermined threshold value.

[0133] (6) A control unit according to (4) or (5), which performs alert control when a value of the output signal of the temperature sensor falls outside a predetermined tolerance range.

[0134] (7) A control unit according to any one of (1) to (3), wherein the sensor is a torque sensor whose output signal changes according to the torque applied to the gear.

[0135] (8) A control unit as described in (7), wherein the reducer has two of the torque sensors, and the control unit performs alert control when a difference between the output signals of the two torque sensors becomes equal to or greater than a predetermined threshold value.

[0136] (9) A control unit according to (7) or (8), which performs alert control when a value of the output signal of the torque sensor falls outside a predetermined allowable range.

[0137] (10) A control unit according to any one of (1) to (3), wherein the sensor is a thrust sensor whose output signal changes according to the thrust force applied to the gear.

[0138] (11) A control unit as described in (10), wherein the reducer has two of the thrust sensors, and the control unit performs alert control when a difference in output signals of the two thrust sensors becomes equal to or greater than a predetermined threshold value.

[0139] (12) A control unit according to (10) or (11), which performs alert control when a value of an output signal of the thrust sensor falls outside a predetermined tolerance range.

[0140] (13) A drive device comprising the control unit according to any one of (1) to (12), the motor, the reducer, and the target object.

[0141] (14) A control method for a drive device having a motor, a reducer that decelerates a rotational motion output from the motor, and an object that moves by the rotational motion output from the reducer, the control method controlling the motor based on a detection value of a sensor mounted on the reducer.

[0142] (15) A control method for a drive device having a plurality of motors, a plurality of reducers that reduce the speed of a rotational motion output from each of the plurality of motors, and a plurality of objects that move by the rotational motion output from each of the plurality of reducers, the control method comprising controlling at least one of the plurality of motors based on a detection value of a sensor mounted on at least one of the plurality of reducers. [Industrial Applicability]

[0143] The present invention can be used in a control unit, a drive device, and a control method. [Explanation of symbols]

[0144] 1,1A,1B reducer 2. Control unit 9 Center axis 10 Input shaft 20 Internal Gear 30 Flex Gear 40 Wave Generator 50 Sensors 51 Sensor board 52 Signal Processing Circuit 60,61,62 Torque sensor 70 Angle Sensor 80,81,82 Thrust sensor 90,91,92 Temperature Sensors 100 Drive unit 101 Base Frame 102, 102A, 102B Arm 103, 103A, 103B Motor C1-C6 bridge circuit Ra-Rx strain gauge V1-V6 Voltmeter r1-r6 resistance wire

Claims

1. A motor; a reducer that reduces the speed of the rotational motion output from the motor; An object that moves due to the rotational motion output from the reducer; A control unit for a drive device having A control unit controls the motor based on a detection value of a sensor mounted on the reducer.

2. A plurality of motors; a plurality of reducers for reducing the speed of rotation output from each of the plurality of motors; A plurality of objects that move due to rotational motion output from each of the plurality of reducers; A control unit for a drive device having A control unit that controls at least one of the plurality of motors based on a detection value of a sensor mounted on at least one of the plurality of reducers.

3. 3. A control unit according to claim 1 or 2, The sensor includes a strain gauge mounted on a gear of the reducer.

4. 4. A control unit according to claim 3, The sensor is a temperature sensor whose output signal varies depending on the temperature of the gear.

5. 5. A control unit according to claim 4, The reducer has two of the temperature sensors, The control unit performs alert control when a difference between the output signals of the two temperature sensors becomes equal to or greater than a predetermined threshold value.

6. 5. A control unit according to claim 4, A control unit performs an alert control when a value of an output signal from the temperature sensor falls outside a predetermined allowable range.

7. 4. A control unit according to claim 3, A control unit, wherein the sensor is a torque sensor whose output signal changes according to the torque applied to the gear.

8. 8. A control unit according to claim 7, The reducer has two of the torque sensors, The control unit performs alert control when a difference between the output signals of the two torque sensors becomes equal to or greater than a predetermined threshold value.

9. 8. A control unit according to claim 7, A control unit that performs alert control when a value of the output signal of the torque sensor falls outside a predetermined allowable range.

10. 4. A control unit according to claim 3, The sensor is a thrust sensor whose output signal changes according to the thrust force applied to the gear.

11. 11. A control unit according to claim 10, The reducer has two of the thrust sensors, The control unit performs alert control when a difference between the output signals of the two thrust sensors becomes equal to or greater than a predetermined threshold value.

12. 11. A control unit according to claim 10, A control unit that performs an alert control when a value of an output signal of the thrust sensor falls outside a predetermined allowable range.

13. A control unit according to claim 1 or 2; The motor; The reducer; The object; A drive unit comprising:

14. A motor; a reducer that reduces the speed of the rotational motion output from the motor; An object that moves due to the rotational motion output from the reducer; A method for controlling a drive device having A control method for controlling the motor based on a detection value of a sensor mounted on the reducer.

15. A plurality of motors; a plurality of reducers for reducing the speed of rotation output from each of the plurality of motors; A plurality of objects that move due to rotational motion output from each of the plurality of reducers; A method for controlling a drive device having A control method for controlling at least one motor of the plurality of motors based on a detection value of a sensor mounted on at least one reducer of the plurality of reducers.

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