Robot system, torque sensor, displacement detection device, detection method, manufacturing method of article, program, and recording medium

Abstract

To improve detection accuracy.SOLUTION: An encoder device 550 includes: an encoder 510; and a displacement calculation section 680 which obtains a phase Φ10 to be used for obtaining a torque value using sine wave signals S1(A) to S2(B) based on a detection signal S from the encoder 510. The encoder 510 has a scale 2 including a pattern section 80, and a sensor head 7 which is arranged to face the scale 2, reads the pattern section 80 of the scale 2, and outputs the detection signal S. The displacement calculation section 680 obtains a relative displacement amount in an X direction and a Y direction of the scale 2 with respect to the sensor head 7 on the basis of the sine wave signals S1(A) to S2(B), and obtains the phase Φ10 on the basis of the arithmetic result.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to sensing technology. [Background technology]

[0002] Industrial robots are installed on production lines in factories and the like to improve the productivity of manufactured goods. Industrial robots include collaborative robots that can work in collaboration with workers. Patent Document 1 discloses an industrial robot equipped with a torque sensor to detect contact with a worker or an object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-104249 A Summary of the Invention [Problem to be solved by the invention]

[0004] The torque sensor is equipped with a displacement detection device such as an encoder device, and calculates a torque value using displacement information detected by the displacement detection device. In recent years, accurate operation is required for driving devices such as robots, and therefore high detection accuracy is required for torque sensors, i.e., displacement detection devices.

[0005] Therefore, an object of the present invention is to improve the detection accuracy. [Means for solving the problem]

[0006] The robot system of the present invention comprises a robot having a reducer and at least one encoder at a joint, and a processing unit that calculates a torque value using phase information based on a detection signal of the encoder, wherein the encoder has a scale including a pattern portion, and a head arranged opposite the scale and reading the pattern portion of the scale to output the detection signal, and the processing unit calculates a first displacement amount of the scale relative to the head in a first direction and a second displacement amount of the scale relative to the head that intersects the first direction based on the phase information, and calculates the torque value based on the first displacement amount and the second displacement amount.

[0007] Moreover, the torque sensor of the present invention comprises at least one encoder arranged in a drive device, and a processing unit that calculates a torque value using phase information based on a detection signal from the encoder, wherein the encoder has a scale including a pattern portion, and a head arranged opposite the scale and that reads the pattern portion of the scale and outputs the detection signal, and the processing unit calculates, based on the phase information, a first displacement amount of the scale relative to the head in a first direction, and a second displacement amount of the scale relative to the head in a second direction intersecting the first direction, and calculates the torque value based on the first displacement amount and the second displacement amount.

[0008] Moreover, a displacement detection device of the present invention includes an encoder arranged in a drive device having a reducer, and a processing unit that determines displacement information in a first direction using phase information based on a detection signal from the encoder, wherein the encoder includes a scale including a pattern portion, and a head arranged opposite the scale and configured to read the pattern portion of the scale and output the detection signal, and the processing unit determines, based on the phase information, a first displacement amount in the first direction of the scale relative to the head, and a second displacement amount in a second direction intersecting the first direction of the scale relative to the head, and determines the displacement information based on the first displacement amount and the second displacement amount.

[0009] Furthermore, the detection method of the present invention is a detection method in which an encoder arranged in a drive device having a reducer has a scale including a pattern portion and a head arranged opposite the scale and reading the pattern portion of the scale to output a detection signal, and a processing unit calculates a torque value using phase information based on the detection signal, wherein the processing unit calculates a first displacement amount of the scale relative to the head in a first direction and a second displacement amount of the scale relative to the head that intersects the first direction based on the phase information, and the processing unit calculates the torque value based on the first displacement amount and the second displacement amount. Effect of the Invention

[0010] According to the present invention, the detection accuracy is improved. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram of a robot system according to a first embodiment. [Diagram 2] FIG. 2 is a partial cross-sectional view showing a joint of the robot arm according to the first embodiment. [Diagram 3] FIG. 2 is a block diagram showing a control system for a joint of a robot arm in the first embodiment. [Figure 4] FIG. 1 is a perspective view of a torque sensor according to a first embodiment. [Diagram 5] 1A is a block diagram showing the configuration of a torque sensor according to a first embodiment, and FIG. 1B is a block diagram showing the functions of the torque sensor according to the first embodiment. [Figure 6] 1A is a schematic diagram of an encoder device which is an example of a displacement detection device according to the first embodiment, and FIG. [Figure 7] 1(a) and 1(b) are explanatory diagrams of a torque sensor according to a first embodiment. [Figure 8] FIG. 2 is an explanatory diagram of a scale according to the first embodiment. [Figure 9]FIG. 2 is a plan view of the light-receiving element array according to the first embodiment. [Figure 10] 2 is a circuit diagram of a circuit portion of a signal processing circuit according to the first embodiment. [Figure 11] 10(a) is a flowchart showing an example of a method for controlling a robot according to the first embodiment, and (b) is a flowchart showing an example of a method for detecting torque according to the first embodiment. [Figure 12] 4 is a graph showing the relationship between the phase and the scale position in the first embodiment. [Figure 13] 1A and 1B are diagrams illustrating the principle of the first embodiment, and 1C is a schematic diagram of a Lissajous waveform in the first embodiment. [Figure 14] 6 is a graph showing the relationship between the difference and the amount of displacement according to the first embodiment. [Figure 15] FIG. 13 is a plan view of a scale according to a modified example. [Figure 16] 10A is a schematic diagram of an encoder device which is an example of a displacement detection device according to a second embodiment, and FIG. 10B is a plan view of a sensor head according to the second embodiment. [Figure 17] FIG. 11 is an explanatory diagram of a scale according to the second embodiment. [Figure 18] FIG. 11 is a plan view of a light-receiving element array according to a second embodiment. [Figure 19] FIG. 11 is a plan view of a light-receiving element array according to a second embodiment. [Figure 20] 13A is a schematic diagram of an encoder device which is an example of a displacement detection device according to a third embodiment, and FIG. 13B is a plan view of a sensor head according to the third embodiment. [Figure 21] FIG. 11 is an explanatory diagram of a scale according to the third embodiment. [Figure 22] 13A is a flowchart showing a pre-processing in the robot system according to the third embodiment, and FIG. 13B is a flowchart showing an example of a torque detection method according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0013] [First embodiment] Fig. 1 is an explanatory diagram of a robot system 100 according to a first embodiment. As shown in Fig. 1, the robot system 100 includes a robot 200 and a robot control device 300. The robot 200 is an industrial robot used to manufacture articles. The robot 200 can perform an operation for manufacturing an article, for example, an operation of grasping a first workpiece W1 and assembling the grasped first workpiece W1 to a second workpiece W2.

[0014] The robot control device 300 is an example of a control unit, and controls the robot 200. A teaching pendant 400, which is an example of a teaching device, can be connected to the robot control device 300. The teaching pendant 400 is a device that teaches the robot 200, and outputs teaching data to the robot control device 300. The robot control device 300 generates trajectory data based on the teaching data, and operates the robot 200 according to the trajectory data.

[0015] The robot 200 includes a robot arm 201 and a robot hand 202 which is an example of an end effector. The robot arm 201 is, for example, a vertically articulated robot arm. A fixed end 201A which is the base end of the robot arm 201 is fixed to a stand 150. A robot hand 202 is attached to a free end 201B which is the tip end of the robot arm 201. The robot arm 201 has a plurality of links 210, 211, 212, and 213, which are rotatably connected at joints J1, J2, and J3. A driving device 230 is provided at each of the joints J1 to J3 of the robot arm 201. A driving device 230 having an appropriate output according to the required torque is used as the driving device 230 for each of the joints J1 to J3.

[0016] In the following, the joint J1 of the robot arm 201 will be described as a representative example, and the other joints J2 and J3 may differ in size and performance, but since they have the same configuration, description thereof will be omitted.

[0017] FIG. 2 is a partial cross-sectional view showing a joint J1 of a robot arm 201 according to the first embodiment. The driving device 230 includes an electric motor 141 as a rotation drive source, a reducer 143 connected to a rotating shaft 142 of the motor 141 and reducing the rotation of the rotating shaft 142 before outputting it, and a torque sensor 500. The rotating shaft 142 of the motor 141 rotates about a rotation axis C0. The link 210 and the link 211 are rotatably connected to each other via a cross roller bearing 147. The motor 141 is a servo motor, for example, a brushless DC servo motor or an AC servo motor. The reducer 143 is a wave gear reducer in the first embodiment. The reducer 143 includes a web generator 151 as an example of an input shaft connected to the rotating shaft 142 of the motor 141, and a circular spline 152 as an example of an output shaft fixed to the link 211. Although the circular spline 152 is connected to the link 211, it may be formed integrally with the link 211. The speed reducer 143 is disposed between the web generator 151 and the circular spline 152, and includes a flexspline 153 connected to the link 210 via a torque sensor 500. The flexspline 153 is formed in a cup shape. The flexspline 153 is flexibly deformed into an elliptical shape by the web generator 151, and meshes with the circular spline 152 at the major axis portion of the elliptical shape. When the web generator 151 rotates, the major axis portion of the elliptical shape of the flexspline 153 rotates, and the meshing position between the flexspline 153 and the circular spline 152 moves in the rotation direction of the web generator 151. When the web generator 151 rotates once, the circular spline 152 rotates relative to the flexspline 153 by an amount equal to the difference in the number of teeth between the flexspline 153 and the circular spline 152. As a result, the circular spline 152 is decelerated at a predetermined reduction ratio with respect to the rotation of the web generator 151, and rotates relative to the flexspline 153. Therefore, the link 211 to which the circular spline 152 is connected rotates about the rotation axis C0 relative to the link 210 to which the flexspline 153 is connected via the torque sensor 500.

[0018] The torque sensor 500 is disposed on the flexspline 153 on the output side of the reducer 143. That is, the torque sensor 500 is disposed between the link 210 and the flexspline 153 of the reducer 143, that is, between the link 210 which is an example of a first link, and the link 211 which is an example of a second link. The torque sensor 500 measures the torque about the rotation axis C0 acting between the link 210 and the link 211, and outputs an electric signal (digital signal) corresponding to the torque value, which is the measured value, to the robot control device 300. The robot control device 300 controls the robot 200 based on the torque value.

[0019] 3 is a block diagram showing a control system for the joint J1 of the robot arm 201 in the first embodiment. The driving device 230 has a driving control device 260 electrically connected to the motor 141 and the robot control device 300. The torque sensor 500 of the driving device 230 is electrically connected to the robot control device 300.

[0020] The robot controller 300 controls the entire robot system. That is, the robot controller 300 controls the operation of the robot 200. The control of the operation of the robot 200 includes position control and force control. During position control, the robot controller 300 generates an operation command based on the position of the hand of the robot 200 and outputs the generated operation command to the drive controller 260. During force control, the robot controller 300 generates an operation command based on a torque value, which is a measurement value from the torque sensor 500, and outputs the generated operation command to the drive controller 260. The drive controller 260 controls the energization of the motor 141 according to the operation command to drive the motor 141. During force control, the robot controller 300 operates the robot 200 based on the torque value, which is an output of the torque sensor 500. For this reason, the performance of the force control of the robot 200 depends on the accuracy of the torque sensor 500, that is, the resolution.

[0021] Fig. 4 is a perspective view of a torque sensor 500 according to the first embodiment. The torque sensor 500 includes a sensor body 590 and a processor 600. The sensor body 590 has a support portion 501 which is an example of a first member fixed to the reducer 143 in Fig. 2 by fastening, and a support portion 502 which is an example of a second member fixed to the link 210 in Fig. 2 by fastening.

[0022] Each of the support parts 501, 502 is a flat plate-like member, and has a circular ring shape centered on the rotation axis C0 as shown in FIG. 4. The support part 502 is displaceable relative to the support part 501 in the rotation direction centered on the rotation axis C0. The shape of each of the support parts 501, 502 is not limited thereto, and may be, for example, a disk shape. The support parts 501, 502 configure flange parts that can be fastened to the reducer 143 and the link 210 by bolts or the like. The support parts 501 and 502 are disposed opposite each other with a gap in the Z direction, which is the direction in which the rotation axis C0 extends, and are connected by an elastic part 503.

[0023] The elastic part 503 has a plurality of leaf springs 504 arranged radially around the rotation axis C0 at intervals. When torque acts between the link 210 and the link 211 shown in FIG. 2, the support part 502 rotates and displaces relative to the support part 501 around the rotation axis C0 by an amount of rotation according to the magnitude of the torque. Each leaf spring 504 is made of a material having an elastic coefficient, i.e., a spring coefficient, according to the measurement range of the target torque and the required resolution. The material of the elastic part 503 is, for example, a resin or a metal, and is preferably a metal. Examples of metal include steel and stainless steel. In the first embodiment, the support part 501, the support part 502, and the elastic part 503 are made of the same material and are formed integrally. The support part 501, the support part 502, and the elastic part 503 do not necessarily have to be formed integrally.

[0024] The sensor body 590 has at least one encoder used to measure the relative displacement between the support part 501 and the support part 502, that is, the torque acting between the support part 501 and the support part 502. The at least one encoder is preferably a plurality of encoders. The plurality of encoders is more preferably four encoders 510. That is, in the first embodiment, the sensor body 590 has four encoders 510. The four encoders 510 have the same configuration. The four encoders 510 are disposed at equal intervals at positions symmetrical by 90 degrees around the rotation axis C0. The number of encoders 510 included in the sensor body 590 is preferably four, but is not limited thereto. The number of encoders 510 included in the sensor body 590 may be one, two, three, or five or more. Each encoder 510 is an incremental type encoder. In this embodiment, an incremental type encoder is used as an example for explanation, but an absolute type encoder may be used. Further, each encoder 510 is preferably an optical, capacitive, or magnetic encoder, and among these, an optical encoder capable of achieving high detection resolution is more preferable. Therefore, in the first embodiment, each encoder 510 is an optical encoder.

[0025] Each encoder 510 may be a linear encoder or a rotary encoder. The relative displacement in the rotation direction between the support part 501 and the support part 502 around the rotation axis C0 is a small displacement at the position of each encoder 510 and can be regarded as a displacement in the translation direction. Therefore, in the first embodiment, each encoder 510 is a linear encoder. Each encoder 510 can detect the relative displacement in the rotation direction of the support part 502 with respect to the support part 501 around the rotation axis C0, that is, the relative displacement in the tangential direction.

[0026] Each encoder 510 has a scale 2 and a sensor head 7, which is an example of a head, arranged to face the scale 2. The sensor head 7 is a sensor unit. The scale 2 is supported by the support portion 501 by being fixed to one of the support portion 501 and the support portion 502, which is the support portion 501 in the first embodiment. The sensor head 7 is supported by the other of the support portion 501 and the support portion 502, which is the support portion 502 in the first embodiment. Note that the scale 2 may be supported by the support portion 502, and the sensor head 7 may be supported by the support portion 501. By using the encoder 510, it is possible to measure the relative displacement between the support portion 501 and the support portion 502 as a relative amount starting from a certain reference position.

[0027] 5(a) is a block diagram of the configuration of the torque sensor 500 according to the first embodiment. The arithmetic processing device 600 has the same number of signal processing circuits 50 as the encoder 510, for example, four, and a computer 650 connected to the four signal processing circuits 50. The computer 650 is, for example, a microcomputer. An example of the configuration of the computer 650 will be described below.

[0028] The computer 650 has a CPU 651 as a processor, which is an example of a processing unit. The computer 650 also has a ROM 652 that stores a program 620 for causing the CPU 651 to perform arithmetic processing to obtain the torque value τ, and a RAM 653 used to temporarily store data and the like. The computer 650 also has an I / O 654 that is an interface with the signal processing circuit 50 and externally connected devices, such as the robot control device 300 and an external storage (not shown). The CPU 651, the ROM 652, the RAM 653, and the I / O 654 are connected to each other via a bus 660 so as to be able to communicate with each other.

[0029] The torque value τ is torque information, i.e., torque data, and may be a standardized value. The CPU 651 obtains phase information from each signal processing circuit 50, performs arithmetic processing according to the program 620 to obtain the torque value τ, and outputs the obtained torque value τ to the robot control device 300.

[0030] In this embodiment, a storage device 670 is configured as an example of a storage unit having a ROM 652 and a RAM 653. Note that the configuration of the storage device 670 is not limited to this. Also, the storage device 670 may be an internal storage, an external storage, or a combination of an internal storage and an external storage.

[0031] In addition, in this embodiment, the non-transitory recording medium readable by the computer 650 is the ROM 652, and the program 620 is recorded in the ROM 652, but this is not limiting. The program 620 may be recorded in any recording medium as long as it is a non-transitory recording medium readable by the computer 650. In addition, as a recording medium for supplying the program 620 to the computer 650, for example, a flexible disk, an optical disk, a magneto-optical disk, a magnetic tape, a non-volatile memory, etc. can be used.

[0032] The arithmetic processing device 600 obtains relative displacement information between the support parts 501 and 502 based on the detection signals, which are encoder signals from the sensor heads 7 of the encoders 510. Then, the arithmetic processing device 600 converts the obtained displacement information into a torque value τ and outputs it to the robot control device 300.

[0033] FIG. 5(b) is a functional block diagram of the torque sensor 500 according to the first embodiment. The torque sensor 500 has a plurality of, for example, four, encoder devices 550 as an example of a plurality of displacement detection devices. Each encoder device 550 has an encoder 510, a signal processing circuit 50, and a part of the functions of a computer 650 shown in FIG. 5(a). A CPU 651 shown in FIG. 5(a) executes a program 620 to function as each displacement calculation unit 680 and a torque calculation unit 681 shown in FIG. 5(b). That is, the CPU 651 functions as the displacement calculation unit 680 of each encoder device 550. The CPU 651 also functions as a torque calculation unit 681 of the torque sensor 500 that calculates a torque value τ using a phase Φ10 that is displacement information calculated by each displacement calculation unit 680. The calculation process of the phase Φ10 by each displacement calculation unit 680 will be described later. Phase Φ10 is relative displacement information of support portion 501 with respect to support portion 502 caused by elastic deformation of elastic portion 503 in response to torque acting on sensor body 590, and does not include elastic deformation of support portion 501.

[0034] FIG. 6(a) is a schematic diagram of an encoder device 550 according to the first embodiment. The scale 2 translates in the X direction relative to the sensor head 7. The moving direction of the scale 2 that translates in the X direction relative to the sensor head 7 is the X direction, the direction intersecting the X direction is the Y direction, and the direction intersecting the X and Y directions is the Z direction. It is preferable that the X, Y, and Z directions are perpendicular to each other. The X direction is a tangential direction. The Y direction is a radial direction. The X direction is an example of a first direction, and the Y direction is an example of a second direction. The X direction is also a positioning direction in the encoder 510. FIG. 6(a) is a schematic diagram of the scale 2 and the sensor head 7 viewed in the X direction. FIG. 6(b) is a plan view of the sensor head 7 according to the first embodiment. FIG. 6(b) is a schematic diagram of the sensor head 7 viewed in the Z direction.

[0035] The encoder 510 is an optical interference type encoder, and is an incremental linear encoder. In the first embodiment, the encoder 510 is a reflective type, but may be a transmissive type. The CPU 651 performs processes such as an interpolation process of the detection signal S obtained from the sensor head 7, a process of writing and reading information to and from the storage device 670, and an output of a position signal.

[0036] The sensor head 7 is disposed at a position facing the scale 2 in the Z direction. The scale 2 has a pattern portion 80. The sensor head 7 reads the pattern portion 80 of the scale 2 and outputs a detection signal S to the signal processing circuit 50. The sensor head 7 includes a light source 1 made of an LED, which is an example of a light-emitting unit, and two light-receiving units 3. 1 ,3 2 Each light receiving unit 3 1 ,3 2 are arranged at an interval in the Y direction with respect to the light source 1. In the first embodiment, the light source 1 is 1 ,3 2 The light receiving unit 3 is placed between the 1 ,3 2 It is preferable to use the same parts for both, as this has the advantage of allowing the use of common parts types and reducing costs, but it is also possible to use different types of parts that are suited to the modulation period of the track that each one reads.

[0037] Receiver unit 3 1 is a photodetector array 9 1 and a light receiving unit 3 2 is a photodetector array 9 2 The light source 1 and the light receiving unit 3 1 ,3 2 The light source 1 and the light receiving unit 3 are mounted on a printed wiring board 4 and sealed with a transparent resin 5 through which light passes. A transparent glass 6 through which light passes is disposed on the surface of the resin 5. With this configuration, the light source 1 and the light receiving unit 3 1 ,3 2 is protected by resin 5 and glass 6.

[0038] The signal processing circuit 50 is configured with a semiconductor element made of, for example, an IC chip. The signal processing circuit 50 is mounted on, for example, the surface of the printed wiring board 4. The position of the signal processing circuit 50 is not limited thereto, and the signal processing circuit 50 may be disposed in a location other than on the printed wiring board 4. In FIG. 6(a), the signal processing circuit 50 is illustrated in a location other than on the printed wiring board 4 for the sake of convenience of explanation. The signal processing circuit 50 processes the signal S from the light receiving element array 9. 1 A circuit section 51 for processing the detection signal S1 acquired from 1 and the light receiving element array 9 2 A circuit section 51 for processing the detection signal S2 acquired from 2 Includes:

[0039] As shown in FIG. 6(a), the pattern portion 80 has two scale tracks 8 1 ,8 2 Includes 2 scale tracks 8 1 ,8 2 are arranged side by side in the Y direction. A divergent light beam emitted from the light source 1 strikes each scale track 8 of the scale 2. 1 ,8 2 Each scale track is illuminated from an oblique angle. 1 ,8 2 The light beam reflected by the light receiving element array 9 1 ,9 2 Each reflected light is reflected toward each light receiving element array 9 1 ,9 2 The reflected light with a distribution of light intensity is incident on each light receiving element array 9 1 ,9 2 Specifically, each light receiving element array 9 1 ,9 2 The amount of light received at decreases as the distance from the light source 1 increases in the Y direction.

[0040] Each light receiving element array 9 1 ,9 2 The light beams received by the detector 51 are converted into electrical signals. The electrical signals are then fed to the respective circuit sections 51 of the signal processing circuit 50 as the detection signals S1 and S2. 1 ,51 2will be sent to.

[0041] In the first embodiment, the support part 501 of the sensor main body 590 shown in Fig. 4 is attached and fixed to the flexspline 153 of the reducer 143 shown in Fig. 2. The flexspline 153 is elliptical deformed by the web generator 151, and the deformation force is also transmitted to the support part 501. Therefore, the support part 501 is deformed by the deformation force.

[0042] 7(a) and 7(b) are explanatory diagrams of the torque sensor 500 as viewed in the direction in which the rotation axis C0 extends. FIG. 7(a) illustrates a state in which the deformation force of the flexspline 153 of the reducer 143 shown in FIG. 2 is not transmitted to the support portion 501 of the torque sensor 500. FIG. 7(b) illustrates a state in which the deformation force of the flexspline 153 of the reducer 143 shown in FIG. 2 is transmitted to the support portion 501 of the torque sensor 500. FIGS. 7(a) and 7(b) illustrate a state in which four encoders 510 are arranged in a row, and the ... 1 ,510 2 ,510 3 ,510 4 These encoders 510 are illustrated as 1 ,510 2 ,510 3 ,510 4 are arranged at equal intervals at positions symmetrical by 90 degrees around the rotation axis C0.

[0043] If no deformation force is applied to the support portion 501 of the torque sensor 500 by the flexspline 153, the support portion 501 maintains its annular shape as shown in FIG. 1 ,510 2 ,510 3 ,510 4 In this case, the displacement in the X direction can be detected accurately.

[0044] When the torque sensor 500 is applied to a joint of the robot 200, a deformation force due to the flexspline 153 acts on the support portion 501 of the torque sensor 500. As a result, the support portion 501 undergoes an elliptical deformation similar to that of the flexspline 153, as shown in FIG. 7(b). When the web generator 151 is rotated in the direction of the arrow to drive the joint of the robot arm 201, the elliptical shape of the flexspline 153, i.e., the elliptical shape of the support portion 501, also rotates in the direction of the arrow. The elliptical shape of the support portion 501 rotates at a frequency twice the rotational speed of the web generator 151. Each encoder 510 1 ,510 2 ,510 3 ,510 4 The scale 2 is fixed to the support 501. In other words, when the joints of the robot arm 201 are rotated, each encoder 510 1 ~510 4 In the figure, the scale 2 periodically fluctuates in the X and Y directions relative to the sensor head 7 at a frequency twice the rotation speed of the web generator 151 .

[0045] For example, as shown in FIG. 7B, it is assumed that the elliptical deformation of the support portion 501 rotates clockwise around the rotation axis C0. 1 and 510 3 In the same manner as when a torque is applied in the clockwise direction, the scale 2 is displaced in the +X direction relative to the sensor head 7. 2 and 510 4 At , the scale 2 is displaced in the −X direction relative to the sensor head 7 in the same manner as if a counterclockwise torque were applied.

[0046] In this manner, each encoder 510 1 ~510 4 The displacement of the scale 2 is superimposed with an error due to the elliptical deformation of the support part 501 in addition to the torque actually applied to the joint of the robot arm 201. The torque sensor 500 has four encoders 510. 1 ~510 4Therefore, by averaging the values ​​detected by these, the error can be reduced to a certain extent. 1 ~510 4 Since there is variation in the amount of displacement due to the elliptical deformation between the images, the errors cannot be completely eliminated by averaging alone.

[0047] Therefore, in the first embodiment, each encoder 510 1 ~510 4 In this case, the displacement in the Y direction is also measured, and the displacement in the X direction is corrected based on the displacement in the Y direction to calculate an accurate torque value.

[0048] FIG. 8 is an explanatory diagram of the scale 2 according to the first embodiment. FIG. 8 illustrates the entire scale 2 and an enlarged portion of the scale 2. The scale 2 has a base material such as glass. The pattern portion 80 is formed by patterning a chromium film on the base material. The base material of the scale 2 may be a resin such as polycarbonate or a metal such as SUS. The pattern portion 80 may be a film such as aluminum as long as it functions as a reflective film.

[0049] Scale track 8 of pattern section 80 1 The pattern is the photodetector array 9 1 The scale track 8 of the pattern section 80 is read. 2 The pattern is the photodetector array 9 2 Scale Track 8 1 The scale track 8 includes at least one pattern sequence 801 as a first pattern sequence. 2 includes a plurality of pattern sequences 802 as at least one second pattern sequence.

[0050] The pattern array 801 includes a plurality of pattern elements 810, which are a plurality of first pattern elements, periodically arranged in the X direction. The plurality of pattern elements 810 are arranged at intervals in the X direction at a predetermined pitch P1, which is the modulation period. Each of the plurality of pattern elements 810 has a shape symmetrical with respect to an axis L1, which is a first axis extending in the Y direction.

[0051] Each pattern row 802 includes a plurality of pattern elements 820, which are a plurality of second pattern elements, periodically arranged in the X direction. The plurality of pattern elements 820 are arranged at intervals in the X direction at a predetermined pitch P2, which is the modulation period. Each of the plurality of pattern elements 820 has an asymmetric shape with respect to an axis L2, which is a second axis extending in the Y direction. In this embodiment, the pitch P1 of the plurality of pattern elements 810 and the pitch P2 of the plurality of pattern elements 820 are the same pitch. In other words, the interval between two adjacent axes L1 and the interval between two adjacent axes L2 are the same.

[0052] Here, pattern element 820 is asymmetric about a virtual axis extending in the Y direction, regardless of the position of the virtual axis in the X direction. In other words, pattern element 820 does not have an axis about which it is line-symmetric. On the other hand, pattern element 810 has one axis about which it is line-symmetric, among the virtual axes extending in the Y direction, and that axis is axis L1.

[0053] In the first embodiment, the multiple pattern arrays 802 are arranged continuously in the Y direction. The length of each pattern array 802 in the Y direction is Y2. A pattern element group 825 is made up of multiple pattern elements 820 in one row that are continuous in the Y direction. In the pattern element group 825, multiple pattern elements 820 of the same shape are arranged in the Y direction at a period of length Y2. In the first embodiment, the multiple pattern element groups 825 are arranged at equal intervals in the X direction at a pitch P2.

[0054] In each pattern row 802, each of the multiple pattern elements 820 arranged at intervals in the X direction includes a portion 821 that is a rectangular first portion, and a portion 822 that is a rectangular second portion arranged shifted in the X direction from the portion 821. The amount of shift in the X direction of the portion 822 from the portion 821 is preferably 1 / 6 of the pitch P2 between two adjacent pattern elements 820 among the multiple pattern elements 820. In addition, it is preferable that the length in the Y direction of the portion 821 and the length in the Y direction of the portion 822 are the same, that is, the length in the Y direction of each of the portions 821 and 822 is Y2 / 2.

[0055] The pitch P1 and the pitch P2 may be different, but are preferably the same. The pitch P1 used to measure torque is preferably as small as possible. By narrowing the pitch P1, a torque sensor 500 with high resolution can be realized. Below, a case where the pitches P1 and P2 are 100 μm and the length Y2 is 50 μm will be described.

[0056] FIG. 9 is a diagram showing a light receiving element array 9 according to the first embodiment. 1 In addition, the light receiving element array 9 2 The configuration is a photodetector array of 9 1 Since the light receiving element array 9 is similar to the light receiving element array 9, the illustration and description thereof will be omitted. 1 The light receiving element array 9 has a plurality of light receiving elements 90, for example 32 light receiving elements 90, arranged at a pitch of 50 μm in the X direction. Each light receiving element 90 has a width X_pd of 50 μm in the X direction and a width Y_pd of 800 μm in the Y direction. 1 The total width X_total is 1600 μm.

[0057] The pattern on the scale 2 is a photodetector array 9 1 Therefore, the detection range on the scale 2 is 800 μm in the X direction and 400 μm in the Y direction. 2In this case, the detection range on the scale 2 is an eight-row pattern array 802 due to the relationship between the width Y_pd and the length Y2. If the value of Y_pd / Y2 is not an integer, the phase in the X direction will differ depending on the detection position in the Y direction. Therefore, it is preferable that the value of Y_pd / Y2 is an integer so that the position in the Y direction does not affect the detection phase in the X direction. 1 ,9 2 The detection signal is output to each circuit section 51 shown in FIG. 1 ,51 2 will be output.

[0058] FIG. 10 shows a circuit section 51 of the signal processing circuit 50 according to the first embodiment. 1 In addition, the circuit section 51 2 51 is a circuit part 1 Since the configuration is the same as that of the circuit section 51 2 The illustration and description of the configuration will be omitted.

[0059] Photodetector array 9 1 The four IV conversion amplifiers 34, 35, 36, and 37, which are first-stage amplifiers, are provided in the rear stage of the light receiving element array 9. 1 Four-phase sine wave outputs S1(A+), S1(B+), S1(A-), and S1(B-) are generated from detection signals, which are current signals read out from each of the light receiving elements 90. The relative phases of the four-phase sine waves are such that, with respect to the detection pitch, S1(A+) is taken as the reference, S1(B+) is approximately +90 degrees, S1(A-) is approximately +180 degrees, and S1(B-) is approximately +270 degrees.

[0060] An A-phase differential amplifier 39 and a B-phase differential amplifier 40 are provided in the subsequent stages of the IV conversion amplifiers 34, 35, 36, and 37. The A-phase differential amplifier 39 and the B-phase differential amplifier 40 perform the calculations of the following equations (1) and (2) using the four-phase sine wave outputs S1(A+), S1(B+), S1(A-), and S1(B-). As a result, the A-phase differential amplifier 39 and the B-phase differential amplifier 40 generate two-phase sine wave signals S1(A) and S1(B) from which the DC component has been removed. S1(A) = S1(A+) - S1(A-) (1) S1(B) = S1(B+) - S1(B-) (2)

[0061] A computer 650 shown in FIG. 5(a) is provided downstream of the A-phase differential amplifier 39 and the B-phase differential amplifier 40, and the two-phase sine wave signals S1(A) and S1(B) are output to the computer 650.

[0062] In this way, the circuit section 51 shown in FIG. 1 is a photodetector array 9 1 The circuit unit 51 generates two-phase sine wave signals S1(A) and S1(B) from the detection signal S1 acquired from the 2 51 is a circuit part 1 Similarly, the photodetector array 9 2 From the detection signal S2 acquired from the input terminal 1, two-phase sine wave signals S2(A) and S2(B) are generated with the DC component removed.

[0063] 8 is a pattern that is detected by the sensor head 7 as a displacement in the X direction when the sensor head 7 and the scale 2 are displaced relatively in the X direction. Note that the pattern of the pattern array 801 is a pattern that is not detected by the sensor head 7 as a displacement in the X direction even when the sensor head 7 and the scale 2 are displaced relatively in the Y direction.

[0064] Moreover, the pattern of the pattern array 802 is a pattern that is detected by the sensor head 7 as a displacement in the X direction when the sensor head 7 and the scale 2 are displaced relatively in the X direction. Furthermore, the pattern of the pattern array 802 is a pattern that is detected by the sensor head 7 as a displacement in the X direction when the sensor head 7 and the scale 2 are displaced relatively in the Y direction.

[0065] In the first embodiment, the computer 650 uses the sine wave signals S1(A), S1(B), S2(A), and S2(B), which are phase information based on the detection signals S1 and S2 from the sensor head 7, to determine the torque value τ from which an error due to the elliptical deformation of the support part 501 has been removed. Of the phase information, the sine wave signals S1(A) and S1(B) are first information, and the sine wave signals S2(A) and S2(B) are second information.

[0066] A specific description will now be given of a method for controlling the robot 200 according to the first embodiment and a method for detecting torque by the torque sensor 500. Fig. 11(a) is a flowchart showing an example of a method for controlling the robot 200 according to the first embodiment.

[0067] First, a method for controlling the robot 200 will be described with reference to the flowchart shown in Fig. 11(a). In step S101, the robot control device 300 controls the robot 200 so that the robot 200 operates according to trajectory data corresponding to a robot program including teaching data. In this case, the robot control device 300 supplies a drive current to the motor 141 of each of the joints J1 to J3 to drive each of the joints J1 to J3. Each of the joints J1 to J3 may or may not be in a state where a torque as an external load is applied thereto.

[0068] In step S102, the robot control device 300 acquires the torque value τ from the torque sensor 500 while controlling the robot 200.

[0069] Next, in step S103, the robot control device 300 determines whether or not the torque value τ is greater than the threshold value TH. In other words, it determines whether or not the robot 200 has come into contact with a worker or an object around the robot 200. If the robot 200 comes into contact with something, the torque value τ exceeds the threshold value TH.

[0070] If the torque value τ is equal to or less than the threshold value TH (S103: NO), the robot control device 300 returns to the process of step S101 and controls the robot 200.

[0071] If the torque value τ is greater than the threshold value TH (S103: YES), in step S104, the robot controller 300 stops the operation of the robot 200. In addition, in step S105, the robot controller 300 executes an alert process. In this embodiment, since the robot system 100 includes three torque sensors 500, the robot controller 300 proceeds to the process of steps S104 and S105 if any one of the three torque values ​​exceeds the threshold value TH.

[0072] Methods for stopping the operation of the robot 200 include stopping it instantly, stopping it slowly, moving it in the opposite direction, switching to impedance control, etc. As an alert process, the robot control device 300 may, for example, cause the robot 200 to issue an error signal (warning), cause the torque value τ to be displayed on a terminal such as the teaching pendant 400, or obtain a log and store it in a memory unit in the robot control device 300.

[0073] The order of the process in step S104 and the process in step S105 may be reversed, or the processes may be performed simultaneously. Also, either the process in step S104 or the process in step S105 may be omitted.

[0074] The torque value τ acquired by the robot control device 300 in step S102 is detected as follows. FIG. 11(b) is a flowchart showing an example of a torque detection method according to the first embodiment. Here, steps S201 to S204 shown in FIG. 11(b) are calculation processes of each displacement calculation unit 680 shown in FIG. 5(b), and step S205 is calculation process of the torque calculation unit 681 shown in FIG. 5(b). Since each displacement calculation unit 680 shown in FIG. 5(b) performs similar calculations, in the following description of the processing of steps S201 to S204, one of the multiple displacement calculation units 680 will be described.

[0075] In step S201, the displacement calculation unit 680 detects a phase Φ11 indicating the amount of displacement in the X direction from the pattern sequence 801.1 Using the sine wave signals S1(A) and S1(B) from the sensor head 7, a first displacement amount in the X direction of the scale 2 relative to the sensor head 7 is obtained as a phase Φ11. The phase Φ11 is obtained from the following equation (3). Φ11=ATAN2[S1(A),S1(B)] ···(3) ATAN2[Y,X] is an arctangent calculation function that distinguishes the quadrant and converts to a phase of 0 to 2π. The relationship between the phase Φ11 and the position of the scale 2 is as shown in the graph of FIG.

[0076] Before calculating the formula (3), the gain ratio and offset error included in the sine wave signals S1(A) and S1(B) due to the offset of each amplifier and gain variation may be corrected with a correction value obtained in advance. For example, for each of the sine wave signals S1(A) and S1(B), the gain ratio, i.e., the amplitude ratio, may be calculated from (maximum value-minimum value) / 2, and a correction value that makes the signal amplitudes equal may be calculated. Similarly, the amount of offset error may be calculated from (maximum value+minimum value) / 2, and a correction value for correcting the offset error may be calculated. These correction values ​​may be stored in the storage device 670.

[0077] Incidentally, the phase Φ11 includes an error Φ10' in the X direction caused by the scale 2 being misaligned in the X direction relative to the sensor head 7 as a result of the support part 501 being elliptical in deformation. Even if the scale 2 is misaligned in the Y direction relative to the sensor head 7 as a result of the support part 501 being elliptical in deformation, this does not affect the phase Φ11.

[0078] In other words, if the phase that does not include the error Φ10' due to elliptical deformation, which would be obtained if it were assumed that the support part 501 was not elliptical deformed, is defined as Φ10, then the phase Φ11 is related by the following equation (4). Φ11 = Φ10 + Φ10' (4) For example, when no torque is applied to the torque sensor 500, the phase Φ10 is zero, but due to the elliptical deformation of the support portion 501, the phase Φ11 that is actually detected becomes an error amount Φ10'.

[0079] Next, in step S202, the displacement calculation unit 680 detects a phase Φ12, which is a displacement amount in the X direction, from the pattern sequence 802. 2 Using the sine wave signals S2(A) and S2(B) from the sensor head 7, the amount of displacement of the scale 2 in the X direction relative to the sensor head 7 is calculated as a phase Φ12. The phase Φ12 is calculated from the following equation (5). Φ12=ATAN2[S2(A),S2(B)] ···(5)

[0080] The phase Φ12 includes an error Φ10′ in the X direction caused by the scale 2 being misaligned in the X direction relative to the sensor head 7 due to the support portion 501 being elliptical.

[0081] Furthermore, the phase Φ12 includes an error in the Y direction, which is caused by the scale 2 being shifted relative to the sensor head 7 in the Y direction due to the elliptical deformation of the support part 501, as an error in the X direction Φ10''. That is, the phase Φ12 is related by the following equation (6). Φ12=Φ10+Φ10'+Φ10''...(6)

[0082] Hereinafter, the principle of the error component Φ10'' being superimposed on the phase Φ12 will be described. For ease of explanation, the explanation will be given assuming that the scale 2 is displaced only in the Y direction relative to the sensor head 7, and there is no relative displacement in the X direction. FIGS. 13(a) and 13(b) are explanatory diagrams of the principle of the error component Φ10'' being superimposed on the phase Φ12 in the first embodiment.

[0083] Scale Truck 8 2 The detection range in the detection area is R2. Only the reflected light from the detection range R2 is detected by the light receiving element array 9 2 The reflected light from the area outside the detection range R2 is received by the light receiving element array 9 2 No light is received at Scale Track 8 2 In the embodiment, the light emitted from the light source 1 is irradiated from an oblique direction, and the light receiving element array 9 2In this article, we will introduce the Scale Track 8 2 The reflected light from the detection range R2 is received from an oblique direction. Therefore, the amount of reflected light is distributed in the detection range R2. The reflected light with a large amount of light is received by the light receiving element array 9 2 This greatly affects the light receiving sensitivity of the light receiving element array 9. 2 13(a) to the state shown in Fig. 13(b), the detection signal S2 changes according to the shape of the pattern element 820 that is asymmetric with respect to the axis L2, even though the detection range R2 has not moved in the X direction.

[0084] In the first embodiment, each pattern element group 825 has a periodic shape, with multiple pattern elements 820 of the same shape continuing in the Y direction. Therefore, if the detection range R2 moves in the Y direction by a length Y2 or more, the phase Φ12 also changes periodically. FIG. 13(c) is a schematic diagram of a Lissajous waveform in the first embodiment. The horizontal axis indicates the sine wave signal S2(A) of the detection signal S2, and the vertical axis indicates the sine wave signal S2(B) of the detection signal S2. When the detection range R2 moves in the Y direction, the point P12 (S2(A), S2(B)) moves back and forth within a predetermined range on the circle of the Lissajous waveform.

[0085] In the first embodiment, as shown in Fig. 8, the amount of deviation in the X direction of portion 822 from portion 821 is 1 / 6 of the pitch P2. In the case of such a pattern, in the Lissajous waveform shown by the dashed line in Fig. 13(c), the harmonic components can be reduced by the principle of optical interference. In this way, since the amount of deviation in the X direction of portion 822 from portion 821 in pattern element 820 is 1 / 6 of the pitch P2, it is possible to detect a highly accurate phase Φ12 from which the third harmonic components have been removed.

[0086] In step S203, the displacement calculation unit 680 calculates a displacement amount ΔY which is a second displacement amount in the Y direction of the scale 2 relative to the sensor head 7. To explain this in detail below, first, the displacement calculation unit 680 calculates a difference ΔΦ by subtracting the phase Φ11 from the phase Φ12. The difference ΔΦ is expressed by the following equation (7). ΔΦ=Φ12-Φ11(=Φ10'')...(7)

[0087] That is, the difference ΔΦ corresponds to the error amount Φ10'', and the displacement calculation unit 680 obtains the error amount Φ10'' by obtaining the difference ΔΦ. The difference ΔΦ, that is, the error amount Φ10'' is a value that changes periodically with respect to the relative displacement amount ΔY in the Y direction of the scale 2 with respect to the sensor head 7. FIG. 14 is a graph showing the relationship between the difference ΔΦ and the displacement amount ΔY. The relationship shown in FIG. 14 is stored in advance in the storage device 670. For example, the relationship between the difference ΔΦ and the displacement amount ΔY is stored in the storage device 670 as table data or an arithmetic expression. The relationship shown in FIG. 14 may be created using, for example, the design values ​​of the light distribution characteristics of the light source and the design values ​​of the pattern sequence 802 of the scale, or may be obtained by performing an experiment. The displacement calculation unit 680 converts the difference ΔΦ into the displacement amount ΔY based on the relationship shown in FIG. 14.

[0088] The pattern element 820 has a pattern in which the portion 821 and the portion 822 are asymmetrically shifted by 1 / 6 of the pitch P2. Therefore, the difference ΔΦ changes periodically within a range of (1 / 6)×2π[rad] between the maximum and minimum values ​​of the difference ΔΦ as the scale 2 is displaced in the Y direction relative to the sensor head 7. The displacement calculation unit 680 counts the number of periods in which the difference ΔΦ changes, and determines the amount of displacement ΔY from the count value at that time and the value of the difference ΔΦ.

[0089] As described above, the displacement calculation section 680 calculates the phase Φ11 from the sine wave signals S1(A) and S1(B), and calculates the amount of displacement ΔY from the phase Φ11 and the sine wave signals S2(A) and S2(B).

[0090] Next, the displacement calculation unit 680 obtains the elliptical shape of the support unit 501, that is, the ellipticity, from the displacement amount ΔX and the displacement amount ΔY in the X direction obtained by converting from the phase Φ11. Here, the positive and negative (±) of the error amount in the X direction caused by the deformation of the support unit 501 into an elliptical shape is reversed depending on the rotation direction of the web generator 151, which is the input shaft of the reducer 143. For this reason, the displacement calculation unit 680 obtains information on the rotation direction of the input shaft of the reducer 143 from the robot control device 300. Specifically, when rotated clockwise as shown in FIG. 7(b), it is estimated that the ellipse is distorted from a circle by a predetermined angle in the clockwise direction, and the ellipticity is a positive value. On the other hand, when rotated counterclockwise, it is estimated that the ellipse is distorted from a circle by a predetermined angle in the counterclockwise direction, and the ellipticity is a negative value.

[0091] The displacement calculation unit 680 determines the amount and direction of the error component in the X direction generated by the deformation of the support unit 501 in the Y direction based on the ellipticity of the support unit 501 taking into account information on the rotation direction of the input shaft of the reducer 143.

[0092] The displacement calculation unit 680 calculates the difference between the ellipticity of the support part 501 and the distance from the rotation axis C0, which is the center of rotation of the support part 501 when it is not subjected to the deforming force shown in Fig. 7(a). This makes it possible to calculate the error Φ10', which is the detection error in the X direction affected by the displacement of the support part 501 based on the elliptical motion of the reducer 143.

[0093] Next, in step S204, the displacement calculation unit 680 obtains the phase Φ10 as the displacement information in the X direction corresponding to the torque value τ from the following equation (8). The phase Φ10, which is the displacement information, corresponds to the relative displacement amount of the support part 501 with respect to the support part 502 due to the elastic deformation of the elastic part 503, with the error due to the elliptical deformation of the support part 501 canceled. Φ10 = Φ11 - Φ10' (8)

[0094] Then, in step S205, the torque calculation unit 681 calculates the torque value τ based on the four phases Φ10 obtained for each of the four encoders 510. For example, the torque calculation unit 681 averages the four phases Φ10 and multiplies the average value by a predetermined coefficient, for example, a sensitivity coefficient proportional to the elastic coefficient of the elastic portion 503, to calculate the torque value τ. Note that the method of calculating the torque value τ is not limited to this, and each phase Φ10 may be converted into a provisional torque value and the four provisional torque values ​​may be averaged to obtain the torque value τ. The displacement calculation unit 680 outputs the calculated torque value τ to the robot control device 300.

[0095] As described above, according to the first embodiment, in the torque sensor 500 mounted on the joint of the robot 200, even if a deformation force due to the elliptical deformation of the reducer 431 acts, the torque value τ can be obtained with high accuracy. That is, the detection accuracy of the torque value τ is improved. Since the detection accuracy of the torque value τ is improved, the operation accuracy of the robot 200 can be improved. For example, by using the torque value τ to determine whether or not to stop the operation of the robot 200, the operation of the robot 200 can be stopped quickly when the robot 200 comes into contact with a worker or an object. Furthermore, when the torque value τ is used to perform force control on the robot 200, the operation of the robot 200 can be controlled with high accuracy.

[0096] The order of the processes in steps S201 and S202 is not limited to the order described above, and the process in step S201 may be executed after the process in step S202. Furthermore, if possible, the processes may be executed simultaneously.

[0097] [Variations] A modified example will now be described. FIG. 15 shows the scale track 8 of the scale 2 of the modified example. 2 FIG. 1 is a plan view of a modified scale track 8. 2 The scale track 8 has a plurality of pattern rows 802. The plurality of pattern rows 802 are arranged consecutively in the Y direction. The length of each pattern row 802 in the Y direction is defined as Y2. 2In the pattern array 802, when focusing on a row of pattern elements 820 continuing in the Y direction, the pattern elements 820 of the same shape are arranged in the Y direction at a period of length Y2. A pattern element group 825 is made up of the pattern elements 820 continuously arranged in a row in the Y direction. In a modified example, the pattern element groups 825 are arranged at equal intervals in the X direction at a pitch P2. Each pattern element 820 in each pattern array 802 is preferably asymmetric with respect to the axis L2, and may be wavy, for example, as shown in FIG.

[0098] [Second embodiment] The second embodiment will be described. Fig. 16(a) is a schematic diagram of an encoder device 550A, which is an example of a displacement detection device according to the second embodiment. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and will not be described. The encoder device 550A includes an encoder 510A, a signal processing circuit 50A, and, like the first embodiment, a displacement calculation unit 680 and a storage device 670.

[0099] In the second embodiment, an encoder 510A shown in Fig. 16(a) is used instead of the encoder 510 in the torque sensor 500 shown in Fig. 4 in the robot system 100 shown in Fig. 1. The following description will be given with appropriate reference to the drawings described in the first embodiment.

[0100] The encoder 510A may be a linear encoder or a rotary encoder, but in the second embodiment, it is a linear encoder as in the first embodiment. The encoder 510A is an optical interference type encoder and is an incremental type encoder. In the second embodiment, the encoder 510A is a reflective type, but it may be a transmissive type.

[0101] The encoder 510A has a scale 2A and a sensor head 7A arranged at a position facing the scale 2A in the Z direction. The scale 2A has a pattern portion 80A. Fig. 16(b) is a plan view of the sensor head 7A according to the second embodiment.

[0102] The sensor head 7A reads the pattern portion 80A of the scale 2A and outputs a detection signal S to the signal processing circuit 50A. The sensor head 7A has a light source 1 made of an LED, which is an example of a light emitting unit, and one light receiving unit 3. The light receiving unit 3 is the same as the light receiving unit 3 described in the first embodiment. 1 That is, in the second embodiment, the light receiving unit 3 2 By omitting this, the sensor head 7A is made smaller.

[0103] The light receiving unit 3 is disposed at a distance from the light source 1 in the Y direction. The light receiving unit 3 has a light receiving element array 9. The light source 1 and the light receiving unit 3 are mounted on a printed wiring board 4 and sealed with transparent resin 5 through which light passes. Transparent glass 6 through which light passes is disposed on the surface of the resin 5. With this configuration, the light source 1 and the light receiving unit 3 are protected by the resin 5 and the glass 6.

[0104] The signal processing circuit 50A is composed of a semiconductor element made of, for example, an IC chip. The signal processing circuit 50A is mounted on, for example, the surface of the printed wiring board 4. The position of the signal processing circuit 50A is not limited thereto, and the signal processing circuit 50A may be disposed in a location other than on the printed wiring board 4. In FIG. 16(a), the signal processing circuit 50A is illustrated in a location other than on the printed wiring board 4 for convenience of explanation. The signal processing circuit 50A includes a switch circuit 41 that switches between a detection signal S1 and a detection signal S2 from the light receiving element array 9 and outputs the detection signal, and a circuit section 51. The circuit configuration of the circuit section 51 is the same as that of the circuit section 51 described in the first embodiment. 1 It has the same configuration as above.

[0105] FIG. 17 is an explanatory diagram of a scale 2A according to the second embodiment. FIG. 17 illustrates the entire scale 2A and an enlarged portion of the scale 2A. The scale 2A has a base material such as glass. The pattern portion 80A is formed by patterning a chrome film on the base material. The base material of the scale 2A may be a resin such as polycarbonate or a metal such as SUS. The pattern portion 80A may be a film such as aluminum as long as it functions as a reflective film.

[0106] The pattern of the pattern portion 80A is read by the light receiving element array 9. The pattern portion 80A includes a plurality of pattern rows 801A as at least one first pattern row. The pattern portion 80A also includes a plurality of pattern rows 802A as at least one second pattern row.

[0107] Each pattern row 801A includes a plurality of pattern elements 810A, which are a plurality of first pattern elements, periodically arranged in the X direction. The plurality of pattern elements 810A are arranged at intervals in the X direction at a predetermined pitch P4, which is the modulation period. Each of the plurality of pattern elements 810A has a shape symmetrical with respect to an axis L4, which is a first axis extending in the Y direction.

[0108] Each pattern array 802A includes a plurality of pattern elements 820A, which are a plurality of second pattern elements, periodically arranged in the X direction. The plurality of pattern elements 820A are arranged at intervals in the X direction at a predetermined pitch P5, which is a modulation period. Each of the plurality of pattern elements 820A has an asymmetric shape with respect to an axis L5, which is a second axis extending in the Y direction. In this embodiment, the pitch P4 of the plurality of pattern elements 810A and the pitch P5 of the plurality of pattern elements 820A are different pitches. For example, the pitch P4 is 100 μm, and the pitch P5 is 200 μm. Note that pattern arrays other than the pattern arrays 801A and 802A may be included in the pattern section 80A.

[0109] In the second embodiment, the multiple pattern sequences 801A and the multiple pattern sequences 802A are arranged alternately in the Y direction. The length of one pair of pattern sequence 801A and pattern sequence 802A in the Y direction is Y4. The pattern portion 80A is configured such that the same shape is repeated in the Y direction at a period of length Y4.

[0110] 18 and 19 are plan views of the light receiving element array 9 according to the second embodiment. The light receiving element array 9 has a plurality of light receiving elements 90, for example, 32 light receiving elements 90. Each light receiving element 90 has a width X_pd of 50 μm in the X direction and a width Y_pd of 800 μm in the Y direction. The total width X_total of the light receiving element array 9 is 1600 μm. If the value of Y_pd / Y4 is not an integer, the phase in the X direction will differ depending on the detection position in the Y direction. Therefore, it is preferable that the value of Y_pd / Y4 is an integer so that the position in the Y direction does not affect the detection phase in the X direction. In the pattern portion 80A, it is preferable that the total sum of the area within the detection range where light is reflected so as to be incident on the light receiving element array 9 is constant regardless of the position in the Y direction. In this way, the amount of light emitted from the light source 1 can be controlled based on the total sum of S(A+), S(B+), S(A-), and S(B-) obtained from the pitch P4 and the pitch P5, respectively.

[0111] In the second embodiment, the detection resolution can be switched by switching the switch circuit 41. By switching the switch circuit 41, the light receiving element array 9 can output the detection signal S1 based on the pattern sequence 801A and the detection signal S2 based on the pattern sequence 802A separately. That is, in the second embodiment, the circuit unit 51 can selectively obtain the detection signal S1 or the detection signal S2 from the light receiving element array 9 by switching the switch circuit 41. The circuit unit 51 generates two-phase sine wave signals S1(A), S1(B) from which the DC component has been removed from the detection signal S1 obtained from the light receiving element array 9. In addition, the circuit unit 51 generates two-phase sine wave signals S2(A), S2(B) from which the DC component has been removed from the detection signal S2 obtained from the light receiving element array 9. Note that, when a pattern sequence other than the pattern sequences 801A, 802A is included in the pattern section 80A, the switch circuit 41 may be configured to be switchable between three or more detection resolutions.

[0112] Here, the pattern of the pattern array 801A is a pattern that is detected by the sensor head 7A as a displacement in the X direction when the sensor head 7A and the scale 2A are displaced relatively in the X direction. Note that the pattern of the pattern array 801A is a pattern that is not detected by the sensor head 7A as a displacement in the X direction even when the sensor head 7A and the scale 2A are displaced relatively in the Y direction.

[0113] Moreover, the patterns of the pattern array 802A are patterns that are detected by the sensor head 7A as a displacement in the X direction when the sensor head 7A and the scale 2A are displaced relatively in the Y direction.

[0114] In the second embodiment, the displacement calculation unit 680 uses the sine wave signals S1(A), S1(B), S2(A), and S2(B), which are phase information based on the detection signals S1 and S2 from the sensor head 7A, to determine the phase Φ10 for determining the torque value τ in the torque calculation unit 681. Of the phase information, the sine wave signals S1(A) and S1(B) are the first information, and the sine wave signals S2(A) and S2(B) are the second information.

[0115] Hereinafter, the control method of the robot 200 (FIG. 1) in the second embodiment is similar to the flow chart of the control method shown in FIG. 11(a) explained in the first embodiment, and therefore the explanation will be omitted. The method of detecting torque by the torque sensor in the second embodiment is also similar to that in the first embodiment, but differs from the first embodiment in that a switching operation is performed by the switch circuit 41. That is, the detection method in the second embodiment is substantially similar to the detection method shown in FIG. 11(b), but the process of step S201 and the process of step S202 are performed by switching the switch circuit 41. Specifically, in step S201, the switch circuit 41 is switched as shown in FIG. 18, and in step S202, the switch circuit 41 is switched as shown in FIG. 19.

[0116] In step S201, by switching the switch circuit 41 as shown in Fig. 18, every third light receiving element in the plurality of light receiving elements 90 is electrically connected to each other, and a current signal is input to one of the IV conversion amplifiers 34 to 37 shown in Fig. 10. This allows the pattern of pitch P4 to be detected.

[0117] In step S202, by switching the switch circuit 41 as shown in Fig. 19, two adjacent light receiving elements in the plurality of light receiving elements 90 are electrically connected to each other, and a current signal is input to one of the IV conversion amplifiers 34 to 37 shown in Fig. 10. This allows the pattern of pitch P5 to be detected.

[0118] As described above, by switching the detection resolution using the switch circuit 41, a single photodetector array 9 can selectively output to the circuit section 51 a detection signal S1 based on the periodic pattern of pitch P4 and a detection signal S2 based on the periodic pattern of pitch P5.

[0119] As described above, according to the second embodiment, similarly to the first embodiment, even if a deformation force due to the elliptical deformation of the reducer 431 acts on the torque sensor, the torque value τ can be obtained with high accuracy. That is, the detection accuracy of the torque value τ is improved. Since the detection accuracy of the torque value τ is improved, the operation accuracy of the robot 200 can be improved. Furthermore, the encoder 510A can be made smaller, and the torque sensor, and therefore the robot, can be made smaller.

[0120] The order of steps S201 and S202 is not limited to the order described above, and step S201 may be executed after step S202. Each pattern element 820A is preferably asymmetric with respect to axis L5, and may be wavy like pattern element 820 shown in FIG.

[0121] [Third embodiment] A third embodiment will be described. Fig. 20(a) is a schematic diagram of an encoder device 550B, which is an example of a displacement detection device according to the third embodiment. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and will not be described. The encoder device 550B includes an encoder 510B, a signal processing circuit 50B, and, like the first embodiment, a displacement calculation unit 680 and a storage device 670.

[0122] In the third embodiment, an encoder 510B shown in Fig. 20(a) is used instead of the encoder 510 in the torque sensor 500 shown in Fig. 4 in the robot system 100 shown in Fig. 1. The following description will be given with appropriate reference to the drawings described in the first embodiment.

[0123] The encoder 510B may be a linear encoder or a rotary encoder, but in the third embodiment, it is a linear encoder as in the first embodiment. The encoder 510B is an optical interference type encoder and is an incremental type encoder. In the third embodiment, the encoder 510B is a reflective type, but it may be a transmissive type.

[0124] The encoder 510B has a scale 2B and a sensor head 7B arranged at a position facing the scale 2B in the Z direction. The scale 2B has a pattern portion 80B. Fig. 20(b) is a plan view of the sensor head 7B according to the third embodiment.

[0125] The sensor head 7B reads the pattern portion 80B of the scale 2B and outputs a detection signal S2 to the signal processing circuit 50B. The sensor head 7B has a light source 1 made of an LED, which is an example of a light emitting unit, and one light receiving unit 3. The light receiving unit 3 is the same as the light receiving unit 3 described in the first embodiment. 2 That is, in the third embodiment, the light receiving unit 3 1 By omitting this, the sensor head 7B is made smaller.

[0126] The light receiving unit 3 is disposed at a distance from the light source 1 in the Y direction. The light receiving unit 3 has a light receiving element array 9. The light source 1 and the light receiving unit 3 are mounted on a printed wiring board 4 and sealed with transparent resin 5 through which light passes. Transparent glass 6 through which light passes is disposed on the surface of the resin 5. With this configuration, the light source 1 and the light receiving unit 3 are protected by the resin 5 and the glass 6.

[0127] The signal processing circuit 50B is configured with a semiconductor element made of, for example, an IC chip. The signal processing circuit 50B is mounted on, for example, the surface of the printed wiring board 4. The position of the signal processing circuit 50B is not limited thereto, and the signal processing circuit 50B may be disposed in a location other than on the printed wiring board 4. In FIG. 20(a), the signal processing circuit 50B is illustrated in a location other than on the printed wiring board 4 for the sake of convenience of explanation. The signal processing circuit 50B includes a circuit section 51 that acquires the detection signal S2 from the light receiving element array 9 and processes the signal. The circuit configuration of the circuit section 51 is the same as that of the circuit section 51 described in the first embodiment. 2 , i.e., circuit section 51 1 It has the same configuration as above.

[0128] FIG. 21 is an explanatory diagram of a scale 2B according to the third embodiment. FIG. 21 illustrates the entire scale 2B and an enlarged portion of the scale 2B. The scale 2B has a base material such as glass. The pattern portion 80B is formed by patterning a chrome film on the base material. The base material of the scale 2B may be a resin such as polycarbonate or a metal such as SUS. Furthermore, the pattern portion 80B may be a film such as aluminum as long as it functions as a reflective film.

[0129] The pattern of the pattern portion 80B is the same as that of the scale track 8 described in the first embodiment. 2 This has the same configuration as the scale track 8 described in the first embodiment. 1 The pattern of the pattern unit 80B is read by the light receiving element array 9. The pattern unit 80B includes a plurality of pattern arrays 802 as at least one pattern array. That is, the pattern unit 80B includes a plurality of pattern arrays 802 having the same configuration as in the first embodiment, and does not include the pattern array 801 described in the first embodiment.

[0130] Each pattern row 802 includes a plurality of pattern elements 820 that are periodically arranged in the X direction. The plurality of pattern elements 820 are arranged at intervals in the X direction at a predetermined pitch P2 that is the modulation period. Each of the plurality of pattern elements 820 has an asymmetric shape with respect to an axis L2 that extends in the Y direction.

[0131] The multiple pattern rows 802 are arranged continuously in the Y direction. The length of each pattern row 802 in the Y direction is Y2. A pattern element group 825 is made up of multiple pattern elements 820 in one row that are continuous in the Y direction. In the pattern element group 825, multiple pattern elements 820 of the same shape are arranged in the Y direction at a period of length Y2. In the third embodiment, the multiple pattern element groups 825 are arranged at equal intervals in the X direction at a pitch P2.

[0132] In each pattern row 802, each of the multiple pattern elements 820 arranged at intervals in the X direction includes a portion 821 that is a rectangular first portion, and a portion 822 that is a rectangular second portion arranged shifted in the X direction from the portion 821. The shift amount in the X direction of the portion 822 from the portion 821 is preferably 1 / 6 of the pitch P2 between two adjacent pattern elements 820 among the multiple pattern elements 820. In addition, it is preferable that the length in the Y direction of the portion 821 and the length in the Y direction of the portion 822 are the same, that is, the length in the Y direction of each of the portions 821 and 822 is Y2 / 2. Note that each pattern element 820 is preferably asymmetric with respect to the axis L2, and may be wavy, for example, as in the pattern element 820 of a modified example shown in FIG.

[0133] Here, the pattern of the pattern array 802 is a pattern that is detected by the sensor head 7B as a displacement in the X direction when the sensor head 7B and the scale 2B are displaced relatively in the X direction. Furthermore, the pattern of the pattern array 802 is a pattern that is detected by the sensor head 7B as a displacement in the X direction when the sensor head 7B and the scale 2B are displaced relatively in the Y direction.

[0134] In the third embodiment, a displacement calculation unit 680 uses sine wave signals S2(A) and S2(B), which are phase information based on a detection signal S2 from a sensor head 7B, to determine a phase Φ10 for determining a torque value τ in a torque calculation unit 681.

[0135] Hereinafter, the control method of the robot 200 (FIG. 1) in the third embodiment will not be described because it is similar to the flowchart of the control method shown in FIG. 11(a) described in the first embodiment. In the third embodiment, the flowchart shown in FIG. 11(a) shows an operation mode in which the robot 200 is caused to actually perform work for manufacturing a product.

[0136] The method of detecting torque by the torque sensor in the third embodiment is different from that in the first embodiment. The robot 200 is an industrial robot. The robot 200 is used to continuously manufacture the same product, and the same operation is repeated during the manufacturing process. Therefore, in the third embodiment, a correction value is measured in advance and stored in the storage device 670. This storage operation is performed in a trial operation mode. Then, in the actual operation of the robot 200, that is, in the operation mode, the detection result of the encoder device 550B included in the torque sensor is corrected with the correction value. The selection between the operation mode, which is the first mode, and the trial operation mode, which is the second mode, is performed, for example, by an operator operating the teaching pendant 400 in FIG. 1. The robot control device 300 executes the mode selected by the operator.

[0137] FIG. 22(a) is a flowchart showing the pre-processing in the robot system according to the third embodiment. That is, the flowchart shown in FIG. 22(a) shows the trial operation mode. In step S301B, the robot control device 300 operates the robot 200 without load according to the trajectory data used in the operation mode. At this time, the CPU 651 shown in FIG. 5(a) corresponding to each joint J1 to J3 obtains a correction value in association with the trajectory data. In step S302B, the CPU 651 stores the correction value associated with the trajectory data in the storage device 670 in FIG. 20(a) as table data 671B. In this way, the profile of the error appearing in the detection result due to the elliptical deformation of the reducer 143 is measured in advance as a correction value.

[0138] Here, the correction value will be specifically described. Operating the robot 200 without a load means rotating the web generators 151 of the reducers 143 of the joints J1 to J3 in a state where the robot 200 does not collide with a person or object. In other words, it means that there is no torque generated when the robot 200 comes into contact with a person or object, or when objects collide with each other when assembling an article. In general, when operating a robot, even if the robot does not collide with a person or object, a load is generated due to the gravity of the earth and the operation of the joints of the robot. For this reason, the torque sensor mounted on each joint of the robot detects a torque depending on the posture and operation of the robot even if there is no collision with a person or object. For this reason, it is necessary to obtain trajectory data according to the posture and operation of the robot and to obtain the correction value. The trajectory data to be obtained is a profile of the rotation angle when the web generator 151 is rotated. In other words, the CPU 651 obtains the correction value by associating it with the rotation angle of the web generator 151 as the trajectory data. This correction value corresponds to the phase Φ10'+Φ10'' shown in equation (6) when the robot 200 is operated with no load. In other words, by operating the robot 200 with no load, a profile equivalent to the error of the phase Φ12 is acquired as the correction value. By calculating the correction value in this way according to the posture and motion of the robot, it becomes possible to accurately detect the contact force when the robot comes into contact with a person or an object when the robot system of this embodiment is applied to a human-collaborative robot, for example.

[0139] The method of controlling the robot 200 in the production process is as explained in the first embodiment using the flowchart shown in FIG. 11(a), and the explanation will be omitted. The torque value τ acquired by the robot control device 300 in step S102 in FIG. 11(a) is detected as follows. FIG. 22(b) is a flowchart showing an example of a torque detection method according to the third embodiment. Here, steps S201B to S203B shown in FIG. 22(b) are calculation processes of the displacement calculation unit 680, and step S204B is calculation processes of the torque calculation unit 681.

[0140] In step S201B, the displacement calculation section 680 reads out the correction value from the table data 671B.

[0141] Next, in step S202B, the displacement calculation unit 680 detects the phase Φ12, which is the amount of displacement in the X direction, from the pattern sequence 802. That is, the displacement calculation unit 680 uses the sine wave signals S2(A) and S2(B) from the circuit unit 51 to determine the amount of displacement in the X direction of the scale 2B relative to the sensor head 7B as the phase Φ12. The phase Φ12 is determined from equation (5) in the first embodiment. The phase Φ12 has the relationship of equation (6) in the first embodiment. The correction value read out in step S201B corresponds to the error (Φ10'+Φ10'') in equation (6).

[0142] Therefore, in step S203B, the displacement calculation section 680 corrects the phase Φ12 with the correction value, that is, subtracts the correction value from the phase Φ12 to obtain the phase Φ10, which is displacement information.

[0143] The process of step S204B is similar to the process of step S205 described in the first embodiment. That is, in step S204B, the torque calculation unit 681 calculates the torque value τ based on the four phases Φ10 obtained for the four encoders 510B, respectively.

[0144] As described above, according to the third embodiment, it is possible to obtain the torque value τ with high accuracy. That is, the detection accuracy of the torque value τ is improved. Since the torque value τ can be obtained with high accuracy, the operation accuracy of the robot 200 can be improved. In addition, the encoder 510B can be made smaller, and the torque sensor 500, and therefore the robot 200, can be made smaller.

[0145] It should be noted that the present invention is not limited to the above-described embodiments, and many modifications are possible within the technical concept of the present invention. Furthermore, the effects described in the embodiments are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments.

[0146] In the above embodiment, the robot arm 201 is a vertically articulated robot arm, but the present invention is not limited to this. The robot arm 201 may be, for example, a horizontally articulated robot arm, a parallel link robot arm, an orthogonal robot, or any other type of robot arm.

[0147] In the above embodiment, the torque sensor is disposed on the output side of the reducer, but the present invention is not limited to this and may be disposed on the input side of the reducer. It is sufficient that the torque sensor is disposed in a position in the joint or the drive device where the elliptical deformation force of the reducer is transmitted.

[0148] In the above embodiment, the encoder is of the incremental type, but the present invention is not limited to this and may be of the absolute type.

[0149] In the above embodiment, the torque sensor has four encoders, but the present invention is not limited to this. For example, the torque sensor may have only one encoder. In this case, the calculation of averaging the phase Φ10 is not necessary when calculating the torque value τ. Of course, it is preferable that the torque sensor has four encoders, and the error in the detected phase can be reduced by averaging the four phases Φ10 detected by the four encoders.

[0150] In the above embodiment, the reducer is a strain wave gear reducer and the flexspline of the strain wave gear reducer is cup-shaped, but the present invention is not limited to this. The flexspline may be in a shape other than a cup shape, for example, a top hat shape.

[0151] In addition, in the above embodiment, a case has been described in which the functions of multiple displacement calculation units 680 and torque calculation units 681 are realized by one CPU 651, but this is not limited to this, and these functions may be realized by multiple CPUs.

[0152] (Other Examples) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]

[0153] 2...scale, 7...sensor head, 80...pattern unit, 100...robot system, 143...reduction gear, 200...robot, 500...torque sensor, 510...encoder, 550...encoder device (displacement detection device), 651...CPU (processing unit)

Claims

1. A robot having a reducer and at least one encoder at a joint; a processing unit that calculates a torque value using phase information based on a detection signal of the encoder, The encoder comprises: a scale including a pattern portion; a head disposed opposite to the scale, reading the pattern portion of the scale and outputting the detection signal; The processing unit includes: determining a first displacement amount of the scale relative to the head in a first direction and a second displacement amount of the scale relative to the head in a second direction intersecting the first direction based on the phase information; determining the torque value based on the first displacement amount and the second displacement amount; A robot system comprising:

2. The pattern portion is at least one first pattern row including a plurality of first pattern elements periodically arranged in the first direction, each of the plurality of first pattern elements being symmetrical with respect to a first axis extending in the second direction; at least one second pattern row including a plurality of second pattern elements periodically arranged in the first direction, each of the plurality of second pattern elements being asymmetric in shape with respect to a second axis extending in the second direction; 2. The robot system according to claim 1 .

3. the at least one second pattern array includes a plurality of second pattern arrays arranged consecutively in the second direction; 3. The robot system according to claim 2.

4. The at least one first pattern sequence includes a plurality of first pattern sequences; the at least one second pattern sequence comprises a plurality of second pattern sequences; The plurality of first pattern rows and the plurality of second pattern rows are alternately arranged in the second direction.

3. The robot system according to claim 2.

5. the phase information includes first information obtained by the head reading the at least one first pattern sequence, and second information obtained by the head reading the at least one second pattern sequence, The processing unit includes: determining the first displacement amount from the first information; determining the second displacement amount from the second information and the first displacement amount; 5. The robot system according to claim 2, wherein the first and second electrodes are arranged in a first direction.

6. The processing unit includes: determining the torque value from displacement information obtained by correcting at least one of the first displacement amount and the second displacement amount with a correction value corresponding to trajectory data of the robot; 2. The robot system according to claim 1 .

7. The pattern portion is The pattern has at least one pattern row including a plurality of pattern elements periodically arranged in the first direction, each of the plurality of pattern elements being asymmetric in shape with respect to an axis extending in a second direction intersecting the first direction.

7. The robot system according to claim 6.

8. The at least one pattern row has a plurality of pattern rows arranged consecutively in the second direction.

8. The robot system according to claim 7.

9. The reducer is a strain wave gear reducer.

9. The robot system according to claim 1, wherein the first and second electrodes are arranged in a first direction.

10. The processing unit further calculates the torque value based on a displacement of the joint in a rotational direction. The robot system according to claim 9 .

11. the at least one encoder comprises a plurality of encoders; The processing unit determines the torque value by using the phase information based on the detection signals from each of the plurality of encoders.

11. The robot system according to claim 1 .

12. At least one encoder disposed on the drive; a processing unit that calculates a torque value using phase information based on a detection signal from the encoder, The encoder comprises: a scale including a pattern portion; a head disposed opposite to the scale, reading the pattern portion of the scale and outputting the detection signal; The processing unit includes: determining a first displacement amount of the scale relative to the head in a first direction and a second displacement amount of the scale relative to the head in a second direction intersecting the first direction based on the phase information; determining the torque value based on the first displacement amount and the second displacement amount; A torque sensor characterized by:

13. The drive device has a reducer, The processing unit includes: determining the torque value from displacement information obtained by correcting at least one of the first displacement amount and the second displacement amount with a correction value corresponding to trajectory data of the driving device; 13. The torque sensor according to claim 12.

14. An encoder disposed in a drive device having a reducer; a processing unit that determines displacement information in a first direction by using phase information based on a detection signal from the encoder, The encoder comprises: a scale including a pattern portion; a head disposed opposite to the scale, reading the pattern portion of the scale and outputting the detection signal; The processing unit includes: determining a first displacement amount of the scale relative to the head in the first direction and a second displacement amount of the scale relative to the head in a second direction intersecting the first direction based on the phase information; determining the displacement information based on the first displacement amount and the second displacement amount; A displacement detection device comprising:

15. The processing unit includes: obtaining the displacement information by correcting at least one of the first displacement amount and the second displacement amount with a correction value corresponding to trajectory data of the driving device; 15. The displacement detection device according to claim 14.

16. A detection method in which an encoder disposed in a drive device having a reducer has a scale including a pattern portion, and a head disposed opposite to the scale, the head reading the pattern portion of the scale and outputting a detection signal, and a processing unit determines a torque value using phase information based on the detection signal, the method comprising: the processing unit determines, based on the phase information, a first displacement amount of the scale relative to the head in a first direction and a second displacement amount of the scale relative to the head in a second direction intersecting the first direction; The processing unit determines the torque value based on the first displacement amount and the second displacement amount. A detection method comprising:

17. the processing unit determines the torque value from displacement information obtained by correcting at least one of the first displacement amount and the second displacement amount with a correction value corresponding to trajectory data of the drive device.

17. The method of claim 16.

18. Manufacturing an article using the robot system according to any one of claims 1 to 11. A method for producing an article comprising the steps of:

19. A program for causing a computer to execute the detection method according to claim 16 or 17.

20. A computer-readable recording medium having the program according to claim 19 recorded thereon.

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