Robot control method and robot system

Abstract

The invention provides a robot control method and a robot system capable of effectively controlling vibration. A robot control method is performed in a robot system including: a robot including a robot arm having a base-end-side joint and a tip-side joint, the base-end-side joint and the tip-side joint having mutually parallel rotation axes; a robot control method includes a robot arm having a distal end joint, and an inertial sensor disposed on a distal end side of the robot arm than the distal end joint and detecting an angular velocity about an axis parallel to a rotation axis and an acceleration in a direction intersecting the rotation axis, the robot control method including: an inertial information acquisition step of acquiring the angular velocity and the acceleration from the inertial sensor; a vibration detection step for detecting the amount of vibration of each of the proximal joint and the distal joint on the basis of the angular velocity and acceleration acquired in the inertia information acquisition step; and a drive control step for controlling vibration on the basis of the amount of vibration detected in the vibration detection step.

Description

Technical Field

[0001] The present invention relates to a control method for a robot and a robot system. Background Art

[0002] The robot arm described in Patent Document 1 has: an arm having a plurality of joints; actuators disposed at each joint; an end effector connected to the end portion of the arm; and an acceleration sensor disposed at the end effector. In such a structured robot arm, the vibration of the end effector is detected by the acceleration sensor, and the vibration is controlled based on the detection result.

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2022-177607

[0004] However, in the robot arm of Patent Document 1, it is impossible to determine which joint among the plurality of joints of the arm causes the vibration of the end effector. Therefore, it is difficult to effectively control the vibration. Summary of the Invention

[0005] A control method for a robot according to the present invention, wherein the control method for the robot is performed in a robot system having: a robot including a robotic arm having a base-end-side joint and a tip-end-side joint, the base-end-side joint and the tip-end-side joint having rotation axes parallel to each other, the tip-end-side joint being located on the tip-end side of the base-end-side joint; and an inertial sensor disposed on the tip-end side of the robotic arm more than the tip-end-side joint and detecting an angular velocity about an axis parallel to the rotation axis and an acceleration in a direction intersecting the rotation axis, the control method for the robot including: an inertial information acquisition step of acquiring the angular velocity and the acceleration from the inertial sensor; a vibration detection step of detecting a vibration amount of each of the base-end-side joint and the tip-end-side joint based on the angular velocity and the acceleration acquired in the inertial information acquisition step; and a drive control step of controlling the vibration based on the vibration amount detected in the vibration detection step.

[0006] A robot system according to the present invention includes: a robot including a robotic arm having a base-end-side joint and a tip-end-side joint, the base-end-side joint and the tip-end-side joint having rotation axes parallel to each other, the tip-end-side joint being located on the tip-end side of the base-end-side joint; an inertial sensor disposed on the tip-end side of the robotic arm more than the tip-end-side joint and detecting an angular velocity about an axis parallel to the rotation axis and an acceleration in a direction intersecting the rotation axis; and a control device that detects a vibration amount of each of the base-end-side joint and the tip-end-side joint based on the angular velocity and the acceleration detected by the inertial sensor and controls the vibration based on the detected vibration amount. Brief Description of the Drawings

[0007] Figure 1 It is an overall view of the robot system according to the first embodiment.

[0008] Figure 2 It is a schematic view showing a posture in which the vibration amounts of the second joint and the third joint cannot be detected only by acceleration.

[0009] Figure 3 It is a schematic view showing a posture in which the vibration amounts of the second joint and the third joint cannot be detected only by angular velocity.

[0010] Figure 4 It is a flowchart showing the control process of the robot.

[0011] Figure 5 It is a schematic view for explaining a method of detecting the vibration amounts of the second joint and the third joint respectively.

[0012] Figure 6 It is a schematic view for explaining a method of detecting the vibration amounts of the second joint and the third joint respectively.

[0013] Figure 7 It is a schematic view for explaining a method of detecting the vibration amounts of the second joint and the third joint respectively.

[0014] Figure 8 It is a schematic view for explaining a method of detecting the vibration amounts of the second joint and the third joint respectively.

[0015] Figure 9 It is a schematic view for explaining a method of detecting the vibration amounts of the second joint and the third joint respectively.

[0016] Figure 10 It is a schematic view for explaining a method of detecting the vibration amounts of the second joint and the third joint respectively.

[0017] Figure 11 It is a block diagram showing the structure of the control unit included in the control device.

[0018] Figure 12 It is a diagram showing an example of the configuration of the inertial sensor.

[0019] Figure 13 It is a diagram showing an example of the configuration of the inertial sensor.

[0020] Figure 14 It is a diagram showing an example of the configuration of the inertial sensor.

[0021] Figure 15 It is a diagram showing an example of the configuration of the inertial sensor.

[0022] Figure 16 It is a schematic diagram showing the robot according to the second embodiment.

[0023] Figure 17 It is a diagram showing the configuration of the inertial sensor.

[0024] Figure 18 It is a schematic diagram showing the robot according to the third embodiment.

[0025] Figure 19 It is a schematic diagram showing the robot according to the fourth embodiment.

[0026] Figure 20 It is a schematic diagram showing the robot according to the fifth embodiment.

[0027] Figure 21 It is a diagram showing the robot according to the sixth embodiment.

[0028] Explanation of reference numerals

[0029] 1: Robot system; 2: Robot; 21: Base; 22: Robot arm; 221: First arm; 222: Second arm; 223: Third arm; 223a: Housing; 223b: Cover; 223c: Inner wall; 223d: Outer wall; 223e: Hollow part; 224: Fourth arm; 225: Fifth arm; 226: Sixth arm; 227: Seventh arm; 231: First joint; 232: Second joint; 233: Third joint; 234: Fourth joint; 235: Fifth joint; 236: Sixth joint; 237: Seventh joint; 24: End effector; 3: Inertial sensor; 31a: Angular velocity detection element; 31b: Angular velocity detection element; 31c: Angular velocity detection element; 31d: Angular velocity detection element; 32a: Acceleration detection element; 32b: Acceleration detection element; 4: Control device; 40: Control unit; 41: Position command generation unit; 42: Position control unit; 43: Speed control unit; 44: Current control unit; 45: Vibration feedback generation unit; 5: Robot; 51: Base; 52: Robot arm; 521: First arm; 522: Second arm; 53: Working head; 531: Spline nut; 532: Ball screw nut; 533: Spline shaft; 533a: Mounting part; 541: First joint; 542: Second joint; 901: Position command; 902: Motor shaft position; 903: Position deviation; 904: Speed command; 905: Speed loop command; 906: Current command; 907: Current; 912: Motor shaft converted arm angular velocity; 913: Motor shaft angular velocity; 914: Vibration angular velocity; 915: Vibration feedback; A: Central axis; Axs: Acceleration; Azs: Acceleration; E: Encoder; J1: First rotation axis; J2: Second rotation axis; J3: Third rotation axis; J4: Fourth rotation axis; J5: Fifth rotation axis; J6: Sixth rotation axis; J7: Seventh rotation axis; J11: First rotation axis; J12: Second rotation axis; J13: Third rotation axis; Kgp: Feedback gain; Kgs: Arm angular velocity scaling factor; Kpp: Position loop proportional gain; Kvi: Speed loop integral gain; Kvp: Speed loop proportional gain; L2: Separation distance; L3: Separation distance; M: Motor; S1: Inertial information acquisition step; S2: Vibration detection step; S3: Drive control step; Vxs: Translation speed; Vzs: Translation speed; ω: Angular velocity; ω2: Angular velocity; ω3: Angular velocity; ωs: Angular velocity. Detailed implementation mode

[0030] Hereinafter, based on the embodiments shown in the drawings, the control method of the robot and the robot system of the present invention will be described in detail.

[0031] First embodiment

[0032] Figure 1 is an overall view of the robot system according to the first embodiment.Figure 2 It is a schematic diagram showing a posture in which the vibration amounts of the second joint and the third joint cannot be detected only by acceleration. Figure 3 It is a schematic diagram showing a posture in which the vibration amounts of the second joint and the third joint cannot be detected only by angular velocity. Figure 4 It is a flowchart showing the control process of the robot. Figures 5 to 10 They are schematic diagrams for explaining the detection methods of the vibration amounts of the second joint and the third joint respectively. Figure 11 It is a block diagram showing the structure of the control unit included in the control device. Figures 12 to 15 They are diagrams showing examples of the arrangements of the inertial sensors respectively.

[0033] Figure 1 The shown robot system 1 includes: a robot 2, an inertial sensor 3 disposed on the robot 2, and a control device 4 that controls the driving of the robot 2.

[0034] The robot 2 is a six-axis vertical articulated robot having six drive axes, and includes a base 21 and a robotic arm 22 rotatably connected to the base 21. The robotic arm 22 is configured such that a first arm 221, a second arm 222, a third arm 223, a fourth arm 224, a fifth arm 225, and a sixth arm 226 are connected via a first joint 231, a second joint 232, a third joint 233, a fourth joint 234, a fifth joint 235, and a sixth joint 236.

[0035] The first arm 221 is rotatably connected to the base 21 via the first joint 231 about a first rotation axis J1. Further, the second arm 222 is rotatably connected to the first arm 221 via the second joint 232 about a second rotation axis J2. Further, the third arm 223 is rotatably connected to the second arm 222 via the third joint 233 about a third rotation axis J3. Further, the fourth arm 224 is rotatably connected to the third arm 223 via the fourth joint 234 about a fourth rotation axis J4. Further, the fifth arm 225 is rotatably connected to the fourth arm 224 via the fifth joint 235 about a fifth rotation axis J5. Further, the sixth arm 226 is rotatably connected to the fifth arm 225 via the sixth joint 236 about a sixth rotation axis J6.

[0036] In addition, among the joints 231, 232, 233, 234, 235, and 236, the second joint 232, the third joint 233, and the fifth joint 235 are respectively bending joints, and the first joint 231, the fourth joint 234, and the sixth joint 236 are respectively twisting joints. In addition, the second rotation axis J2 is orthogonal to the first rotation axis J1, the third rotation axis J3 is parallel to the second rotation axis J2, the fourth rotation axis J4 is orthogonal to the third rotation axis J3, the fifth rotation axis J5 is orthogonal to the fourth rotation axis J4, and the sixth rotation axis J6 is orthogonal to the fifth rotation axis J5. In addition, the second rotation axis J2, the third rotation axis J3, and the fifth rotation axis J5 respectively face the horizontal direction.

[0037] It should be noted that in the description of this application, the meaning of "parallel" is that in addition to the case where the axes of each other are parallel, it also includes the case where, relative to parallel, there is a deviation that can be regarded as the same as parallel from the perspective of technical common sense, such as the deviation caused by the dimensional accuracy, assembly accuracy, etc. of the robot 2. In addition, the meaning of "orthogonal" is that in addition to the case where the axes of each other are orthogonal, it also includes the case where, relative to orthogonal, there is a deviation that can be regarded as the same as orthogonal from the perspective of technical common sense, such as the deviation caused by the dimensional accuracy, assembly accuracy, etc. of the robot 2.

[0038] In such a robot 2, the second joint 232 is the "base-end side joint" of this application, and the third joint 233 is the "tip-end side joint" of this application.

[0039] In addition, each of the joints 231, 232, 233, 234, 235, and 236 is provided with a motor M, a reduction gear (not shown) that reduces the rotation speed of the motor M and outputs, and an encoder E that detects the rotation amount of the motor M. The control device 4 drives the motor M through servo control that feeds back the output of the encoder E, thereby controlling the rotation amounts of the joints 231, 232, 233, 234, 235, and 236.

[0040] In addition, an end effector 24 is installed at the end portion of the robotic arm 22, that is, the sixth arm 226. The end effector 24 is detachable from and attachable to the sixth arm 226, and an end effector 24 corresponding to the operation content performed by the robot 2 is appropriately assembled.

[0041] In addition, as Figure 1As shown in the figure, the inertial sensor 3 is disposed on the third arm 223. The inertial sensor 3 includes: an angular velocity detection element 31a that detects the angular velocity ωs about an axis in the same direction as the second rotation axis J2 and the third rotation axis J3; and an acceleration detection element 32a that detects the acceleration Azs in a direction that intersects, particularly is orthogonal to, the second rotation axis J2 and the third rotation axis J3. Specifically, the acceleration Azs is a vertical acceleration generated by the rotational movement of the third arm 223 caused by driving at least one of the second joint 232 and the third joint 233. By disposing the inertial sensor 3 on the third arm 223, the state where the detection axis of the angular velocity detection element 31a is parallel to the second rotation axis J2 and the third rotation axis J3 can be maintained regardless of the posture, and thus the angular velocity ωs and the acceleration Azs can be detected more reliably.

[0042] In addition, as Figure 1 shown in the figure, the inertial sensor 3 is disposed on the third arm 223. The inertial sensor 3 includes: an angular velocity detection element 31a that detects the angular velocity ωs about an axis in the same direction as the second rotation axis J2 and the third rotation axis J3; and an acceleration detection element 32a that detects the acceleration Azs in a direction that intersects, particularly is orthogonal to, the second rotation axis J2 and the third rotation axis J3. Specifically, the acceleration Azs is a vertical acceleration generated by the rotational movement of the third arm 223 caused by driving at least one of the second joint 232 and the third joint 233. By disposing the inertial sensor 3 on the third arm 223, the state where the detection axis of the angular velocity detection element 31a is parallel to the second rotation axis J2 and the third rotation axis J3 can be maintained, and the state where the detection axis of the acceleration detection element 32a is orthogonal to the second rotation axis J2 and the third rotation axis J3 can be maintained regardless of the posture, and thus the angular velocity ωs and the acceleration Azs can be detected more reliably.

[0043] As described above, since the inertial sensor 3 is disposed on the third arm 223, the inertial sensor 3 can be said to be disposed on the arm between the third joint 233, which is the end-side joint, and the sixth joint 236, which is the most end-side joint. In other words, it can be said that the inertial sensor 3 is not disposed on the sixth arm 226. Thus, by disposing the inertial sensor 3 while avoiding the arm at the most end, the number of joints between the inertial sensor 3 and the third joint 233 can be controlled to be as small as possible. Therefore, the angular velocity ωs and the acceleration Azs can be easily detected without being affected by the posture of the robotic arm 22.

[0044] In the present embodiment, as the inertial sensor 3, a single sensor unit including the angular velocity detection element 31a and the acceleration detection element 32a is used, but it is not limited thereto, and a structure in which an angular velocity sensor including the angular velocity detection element 31a and an acceleration sensor including the acceleration detection element 32a are separately disposed may also be used.

[0045] The control device 4 controls the driving of the robot 2. The control device 4 has, for example: a processor (CPU) composed of a computer for processing information; a memory connected to the processor in a communicable manner; and an external interface for connecting to an external device. Various programs executable by the processor are stored in the memory, and the processor can read and execute the programs stored in the memory and the like.

[0046] Above, the structure of the robot system 1 has been described. For example, when the inertial sensor 3 can only detect the acceleration Azs, as Figure 2 shown, in the posture where the second arm 222 and the third arm 223 both extend along the horizontal direction, it is impossible to distinguish the angular velocity ω2 generated by the vibration of the second joint 232 from the angular velocity ω3 generated by the vibration of the third joint 233. Further, for example, when the inertial sensor 3 can only detect the angular velocity ωs, as Figure 3 shown, the second arm 222 faces the vertical direction and the third arm 223 faces the horizontal direction, in the posture where they are orthogonal, it is impossible to distinguish the angular velocity ω2 generated by the vibration of the second joint 232 from the angular velocity ω3 generated by the vibration of the third joint 233. In contrast, in the robot system 1, the inertial sensor 3 can detect the angular velocity ωs and the acceleration Azs, and can distinguish the vibration of the second joint 232 from the vibration of the third joint 233 based on the relationship between the angular velocity ωs and the acceleration Azs. Hereinafter, this method will be described.

[0047] As Figure 4 shown, the control method of the robot 2 includes: an inertial information acquisition step S1 of acquiring the angular velocity ωs and the acceleration Azs from the inertial sensor 3; a vibration detection step S2 of detecting the vibration amounts of the respective joints of the second joint 232 and the third joint 233 based on the angular velocity ωs and the acceleration Azs acquired in the inertial information acquisition step S1; and a drive control step S3 of controlling the vibration of the vibrating joints based on the detection result of the vibration detection step S2. Hereinafter, these steps S1 to S3 will be described in detail.

[0048] Inertial information acquisition step S1

[0049] In the inertial information acquisition step S1, the control device 4 acquires the angular velocity ωs and the acceleration Azs from the inertial sensor 3.

[0050] Vibration detection step S2

[0051] In the vibration detection step S2, the control device 4 detects the vibration amounts of the respective joints of the second joint 232 and the third joint 233 based on the angular velocity ωs and the acceleration Azs acquired in the inertial information acquisition step S1.

[0052] As an example, as Figure 5 shown, a detection method in a posture where the second arm 222 and the third arm 223 extend straight in the horizontal direction will be described. It should be noted that, as described above, in this posture, only by the acceleration Azs, the vibration amounts of the joints of the second joint 232 and the third joint 233 cannot be detected. In addition, as shown in the figure, the separation distance between the second rotation axis J2 and the third rotation axis J3 is set as L2, and the separation distance between the third rotation axis J3 and the inertial sensor 3 is set as L3. In Figure 5 the case of, the vertical translation speed Vzs of the inertial sensor 3 is expressed by Vzs = L×ω. The translation speed Vzs is calculated by integrating the acceleration Azs detected by the inertial sensor 3. In addition, L is the separation distance between the rotation axis of the joint generating vibration and the inertial sensor 3, and ω is the angular velocity of the joint generating vibration around the rotation axis.

[0053] As Figure 6 shown, when the second joint 232 vibrates at an angular velocity ω2, Vzs = (L2 + L3)×ω2, ω = ω2. On the other hand, as Figure 7 shown, when the third joint 233 vibrates at an angular velocity ω3, Vzs = L3×ω3, ω = ω3. Thus, in the case where the second joint 232 vibrates and the case where the third joint 233 vibrates, the relationship between the translation speed Vzs and the angular velocity ω is different. Specifically, Vzs / ω when the second joint 232 vibrates is greater than Vzs / ω when the third joint 233 vibrates. Therefore, based on the relationship between the translation speed Vzs and the angular velocity ω, the vibration amounts of the joints of the second joint 232 and the third joint 233 can be discriminated.

[0054] According to the above relationship, the following equations (1) and (2) using the Jacobian matrix hold. Therefore, based on L2, L3 measured in advance, the angular velocity ωs detected by the inertial sensor 3, and the translation speed Vzs calculated from the acceleration Azs detected by the inertial sensor 3, the angular velocities ω2 and ω3 can be obtained. Then, based on the obtained values of the angular velocities ω2 and ω3, the vibration amounts of the joints of the second joint 232 and the third joint 233 can be discriminated.

[0055] Equation 1

[0056]

[0057] Equation 2

[0058]

[0059] In addition, as another example, as Figure 8As shown, a posture will be described in which the second arm 222 faces the vertical direction, the third arm 223 faces the horizontal direction, and the second arm 222 is orthogonal to the third arm 223. At this time, the separation distance in the vertical direction from the center of the third arm 223 to the detection center of the acceleration detected by the inertial sensor 3 is set as Lsz. It should be noted that, as described above, in this posture, the vibration amounts of the joints of the second joint 232 and the third joint 233 cannot be detected only by the angular velocity ωs.

[0060] As Figure 9 shown, when the second joint 232 vibrates at an angular velocity ω2, Vzs = L3×ω2, ω = ω2. On the other hand, as Figure 10 shown, when the third joint 233 vibrates at an angular velocity ω3, , ω = ω3. Thus, the relationship between the translational velocity Vzs and the angular velocity ω is different when the second joint 232 vibrates and when the third joint 233 vibrates. Therefore, based on the relationship between the translational velocity Vzs and the angular velocity ω, the vibration amounts of the joints of the second joint 232 and the third joint 233 can be discriminated.

[0061] Based on the above relationship, the following equations (3) and (4) of the Jacobian matrix hold. Therefore, based on L2, L3, Lsz measured in advance, the angular velocity ωs detected by the inertial sensor 3, and the translational velocity Vzs calculated from the acceleration Azs detected by the inertial sensor 3, the angular velocities ω2 and ω3 can be obtained. Then, based on the obtained values of the angular velocities ω2 and ω3, the vibration amounts of the joints of the second joint 232 and the third joint 233 can be discriminated.

[0062] Equation 3

[0063]

[0064] Equation 4

[0065]

[0066] Above, two representative postures in which it is impossible to discriminate which of the second joint 232 and the third joint 233 is vibrating only by either the angular velocity ωs or the acceleration Azs have been described. Of course, in other postures, the vibration amounts of the joints of the second joint 232 and the third joint 233 can also be discriminated based on the relationship between the angular velocity ωs and the acceleration Azs.

[0067] In the robot 2, in any posture, the following equations (5) and (6) of the Jacobian matrix J hold. It should be noted that the Jacobian matrix J represents the position of the inertial sensor 3 and becomes different values according to the rotation amounts of the second joint 232 and the third joint 233. The position of the inertial sensor 3 is detected based on the outputs of the encoders E provided in the second joint 232 and the third joint 233, for example. Therefore, the angular velocities ω2 and ω3 can be obtained based on the previously measured separation distances L2, L3, Lsz, the angular velocity ωs detected by the inertial sensor 3, and the translational velocity Vzs calculated from the acceleration Azs detected by the inertial sensor 3. Then, the vibration amounts of the respective joints of the second joint 232 and the third joint 233 can be discriminated based on the obtained values of the angular velocities ω2 and ω3.

[0068] Equation 5

[0069]

[0070] Equation 6

[0071]

[0072] According to the method as described above, the vibration amounts of the respective joints of the second joint 232 and the third joint 233 can be discriminated. In particular, the vibration amounts of the respective joints of the second joint 232 and the third joint 233 can be discriminated based on the previously measured separation distances L2, L3, LSZ, the angular velocity ωs detected by the inertial sensor 3, and the translational velocity Vzs calculated from the acceleration Azs detected by the inertial sensor 3. Therefore, this detection can be easily performed.

[0073] Drive control step S3

[0074] In the drive control step S3, the control device 4 controls the drive of the robotic arm 22 based on the detection result of the vibration detection step S2. Specifically, the control device 4 detects and controls the vibrations generated in the second joint 232 and the third joint 233 based on the vibration amounts of the respective joints discriminated in the vibration detection step S2. Thus, by controlling the vibration based on the vibration amounts of the respective joints, more appropriate control can be performed, and the vibration can be reduced more reliably and effectively.

[0075] For example, if an example of the control of the second joint 232 is cited, then as Figure 11 shown, the control device 4 has a control unit 40 that controls the drive of the second joint 232. Moreover, the control unit 40 has a position command generation unit 41, a position control unit 42, a speed control unit 43, a current control unit 44, and a vibration feedback generation unit 45.

[0076] The vibration feedback generation unit 45 multiplies the vibration amount discriminated in step S2 based on the angular velocity ωs detected by the inertial sensor 3 and the acceleration Azs detected by the inertial sensor 3, that is, the angular velocity ω by the arm angular velocity scaling coefficient Kgs, and obtains the arm angular velocity 912 converted to the motor shaft. In addition, the vibration feedback generation unit 45 performs time differentiation on the rotation angle of the motor M detected by the encoder E, that is, the motor shaft position 902, and obtains the motor shaft angular velocity 913 which is the angular velocity of the motor shaft. Next, the vibration feedback generation unit 45 subtracts the motor shaft angular velocity 913 from the arm angular velocity 912 converted to the motor shaft to obtain the vibration angular velocity 914. Next, the vibration feedback generation unit 45 multiplies the vibration angular velocity 914 by the feedback gain Kgp to obtain the vibration feedback 915.

[0077] The position command generation unit 41 generates a position command 901 for the motor M based on a program generated by the host computer. The position control unit 42 first obtains a position deviation 903 by subtracting the motor shaft position 902 detected by the encoder E from the position command 901. Next, the position control unit 42 multiplies the position deviation 903 by the position loop proportional gain Kpp to obtain a speed command 904.

[0078] The speed control unit 43 is configured by proportional / integral control. The speed control unit 43 first adds the speed command 904 and the vibration feedback 915 generated by the vibration feedback generation unit 45 to obtain a speed loop command 905. Next, the speed control unit 43 adds a proportional term obtained by multiplying the speed loop command 905 by the speed loop proportional gain Kvp and an integral term obtained by multiplying the integral value of the speed loop command 905 by the speed loop integral gain Kvi, thereby obtaining a current command 906.

[0079] The current control unit 44 performs control so that the current 907 for driving the motor M coincides with the current command 906, that is, the current 907 follows the current command 906. And the motor M is driven by the current 907 controlled by the current control unit 44.

[0080] The above describes an example of the control. Next, an example of the arrangement of several inertial sensors 3 will be described. For example, as Figure 12As shown, when the inertial sensor 3 is viewed from above in a direction perpendicular to the vertical direction, that is, a direction orthogonal to the third rotation axis J3 and the central axis A of the third arm 223, it is located on the central axis A of the third arm 223. In the case of the robot system 1, the central axis A is orthogonal to the third rotation axis J3 and parallel to the fourth rotation axis J4. In other words, the central axis A is parallel to the extending directions of the third arm and the fourth arm. With such a configuration, the configuration of the inertial sensor 3 becomes easy. Further, the inertial sensor 3 is disposed at the end on the fourth joint 234 side, that is, the end on the side opposite to the third joint 233. Thereby, the inertial sensor 3 can be disposed in a manner that is as separated from the third rotation axis J3 as possible, and thus a larger acceleration Azs can be detected.

[0081] In addition, for example, as Figure 13 shown, when a motor M as a drive source is disposed within the third arm 223, the inertial sensor 3 is disposed separately from the motor M. Thereby, the vibration generated by the drive of the motor M is difficult to be transmitted to the inertial sensor 3, and the angular velocity ωs and the acceleration Azs can be detected with high precision by the inertial sensor 3. It should be noted that the motor M disposed within the third arm 223 can also be the motor M provided in any joint. For example, it can be the motor M provided in the third joint 233 or the motor M provided in the fourth joint 234.

[0082] In addition, for example, as Figure 14 shown, the inertial sensor 3 is disposed within the third arm 223. Thereby, the inertial sensor 3 can be protected from the influence of moisture, dust, etc. In addition, the inertial sensor 3 is disposed on the wall portion of the third arm 223. Specifically, the third arm 223 has a housing 223a connected to other arms and a cover 223b mounted on the housing 223a, and the inertial sensor 3 is disposed on the wall portion of the cover 223b. Since a speed reducer and the motor M are fixed in the housing 223a, by disposing the inertial sensor 3 on the cover 223b, the vibration generated from the speed reducer and the motor M is difficult to be transmitted to the inertial sensor 3. Therefore, the angular velocity ωs and the acceleration Azs can be detected with high precision by the inertial sensor 3.

[0083] In addition, for example, as Figure 15 shown, the wall portion, that is, the cover 223b has an inner wall 223c, an outer wall 223d, and a hollow portion 223e located between the inner wall 223c and the outer wall 223d, and the inertial sensor 3 is disposed in the hollow portion 223e. Thereby, by housing the inertial sensor 3 within the cover 223b, the inertial sensor 3 can be protected from the influence of moisture, dust, etc. Further, the inertial sensor 3 is disposed on the outer wall 223d. Thereby, the vibration generated from the speed reducer and the motor M is difficult to be transmitted to the inertial sensor 3. Therefore, the angular velocity ωs and the acceleration Azs can be detected with high precision by the inertial sensor 3.

[0084] As described above, the robot system 1 has been described. As described above, in the control method of the robot 2 performed in such a robot system 1, the robot system 1 includes: a robot 2 having a robotic arm 22, the robotic arm 22 having a base-side joint, i.e., a second joint 232, and a distal-side joint, i.e., a third joint 233, the second joint 232 and the third joint 233 having rotation axes parallel to each other, the third joint 233 being located on the distal side of the second joint 232; and an inertial sensor 3 disposed on the distal side of the robotic arm 22 relative to the third joint 233 and detecting an angular velocity ω about an axis parallel to the rotation axes of the second joint 232 and the third joint 233, i.e., a second rotation axis J2 and a third rotation axis J3, and an acceleration Azs in a direction intersecting the second rotation axis J2 and the third rotation axis J3. The control method of the robot 2 includes: an inertial information acquisition step S1 of acquiring the angular velocity ωs and the acceleration Azs from the inertial sensor 3; a vibration detection step S2 of detecting the vibration amounts of the joints of the second joint 232 and the third joint 233 respectively based on the angular velocity ωs and the acceleration Azs acquired in the inertial information acquisition step S1; and a drive control step S3 of controlling the vibration based on the vibration amounts detected in the vibration detection step S2. Thus, by controlling the vibration based on the vibration amounts of the respective joints, more appropriate control can be performed, and the vibration can be reduced more reliably and effectively.

[0085] In addition, as described above, the robot system 1 includes: a robot 2 having a robotic arm 22, the robotic arm 22 having a base-side joint, i.e., a second joint 232, and a distal-side joint, i.e., a third joint 233, the second joint 232 and the third joint 233 having rotation axes parallel to each other, the third joint 233 being located on the distal side of the second joint 232; and an inertial sensor 3 disposed on the distal side of the robotic arm 22 relative to the third joint 233 and detecting an angular velocity ω about an axis parallel to the rotation axes of the second joint 232 and the third joint 233, i.e., a second rotation axis J2 and a third rotation axis J3, and an acceleration Azs in a direction intersecting the second rotation axis J2 and the third rotation axis J3; and a control device 4 that detects the vibration amounts of the joints of the second joint 232 and the third joint 233 respectively based on the angular velocity ωs and the acceleration Azs detected by the inertial sensor 3, and controls the vibration based on the detected vibration amounts. Thus, by controlling the vibration based on the vibration amounts of the respective joints, more appropriate control can be performed, and the vibration can be reduced more reliably and effectively.

[0086] In addition, as described above, the control device 4 detects the vibration amounts of the joints of the second joint 232 and the third joint 233 based on the separation distance L2 between the second rotation axis J2 of the second joint 232 and the third rotation axis J3 of the third joint 233, and the separation distance L3 between the third rotation axis J3 of the third joint 233 and the inertial sensor 3. Thereby, the vibration amounts of the joints of the second joint 232 and the third joint 233 can be detected by a simple method.

[0087] In addition, as described above, the robot 2 has a base 21, and the robotic arm 22 has: a first arm 221 connected to the base 21 and rotatable relative to the base 21; a second arm 222 connected to the first arm 221 via a second joint 232; and a third arm 223 connected to the second arm 222 via a third joint 233. And, the inertial sensor 3 is disposed on the third arm 223. With such a structure, regardless of the posture, the state where the detection axis of the angular velocity detection element 31a is parallel to the second rotation axis J2 and the third rotation axis J3 can be maintained, so that the angular velocity ωs and the acceleration Azs can be detected more reliably.

[0088] In addition, as described above, when viewed from above in a direction orthogonal to the second rotation axis J2, the third rotation axis J3, and the central axis A of the third arm 223, the inertial sensor 3 is located on the central axis A of the third arm 223. With such a configuration, the configuration of the inertial sensor 3 becomes easy.

[0089] In addition, as described above, the inertial sensor 3 is disposed at the end of the third arm 223 on the side opposite to the third joint 233. Thereby, the inertial sensor 3 can be disposed so as to be separated from the third rotation axis J3 as much as possible, so that a larger acceleration Azs can be detected.

[0090] In addition, as described above, the robot 2 has a motor M disposed inside the third arm 223 and serving as a drive source for driving the robotic arm 22. And, the inertial sensor 3 is disposed separately from the motor M. Thereby, the vibration generated by the drive of the motor M is difficult to be transmitted to the inertial sensor 3, and the angular velocity ωs and the acceleration Azs can be detected with high precision by the inertial sensor 3.

[0091] In addition, as described above, the inertial sensor 3 is disposed inside the third arm 223. Thereby, the inertial sensor 3 can be protected from the influence of moisture, dust, etc.

[0092] In addition, as described above, the inertial sensor 3 is disposed on the wall portion of the third arm 223, i.e., the cover 223b. Thereby, the vibration generated from the speed reducer and the motor M is difficult to be transmitted to the inertial sensor 3. Therefore, the angular velocity ωs and the acceleration Azs can be detected with high precision by the inertial sensor 3.

[0093] In addition, as described above, the cover 223b serving as the wall portion has an inner wall 223c, an outer wall 223d, and a hollow portion 223e located between the inner wall 223c and the outer wall 223d. Further, the inertial sensor 3 is disposed in the hollow portion 223e. Thereby, the inertial sensor 3 can be protected from the influence of moisture, dust, and the like.

[0094] Second Embodiment

[0095] Figure 16 FIG. is a schematic view showing a robot according to the second embodiment. Figure 17 FIG. is a view showing the arrangement of the inertial sensor.

[0096] The robot system 1 according to the present embodiment is the same as the robot system 1 of the first embodiment described above, except for the structure and arrangement of the inertial sensor 3. It should be noted that in the following description, regarding the robot system 1 of the present embodiment, the differences from the first embodiment described above will be mainly described, and the description of the same matters will be omitted. In addition, in the drawings of the present embodiment, the same reference numerals are given to the same structures as those in the above-described embodiment.

[0097] As Figure 16 shown, in the robot system 1 of the present embodiment, the inertial sensor 3 is disposed in the fourth arm 224. Thereby, by disposing the inertial sensor 3 in the fourth arm 224, the inertial sensor 3 can be disposed further apart from the second rotation axis J2 and the third rotation axis J3, and thus a larger acceleration Azs can be detected. Therefore, the vibration amounts of the joints of the second joint 232 and the third joint 233 can be determined with higher accuracy.

[0098] In such a structure, as the fourth joint 234 rotates, the detection axis of the inertial sensor 3 rotates with respect to the second rotation axis J2 and the third rotation axis J3. Therefore, in the structure having one angular velocity detection element 31a and one acceleration detection element 32a like the inertial sensor 3 in the first embodiment described above, the angular velocity ωs and the acceleration Azs cannot be detected according to the orientation of the fourth joint 234.

[0099] Therefore, in addition to the angular velocity detection element 31a, the inertial sensor 3 of the present embodiment further includes an angular velocity detection element 31b having a detection axis that intersects, particularly orthogonally, with the detection axis of the angular velocity detection element 31a and the fourth rotation axis J4. In addition, in addition to the acceleration detection element 32a, the inertial sensor 3 of the present embodiment further includes an acceleration detection element 32b having a detection axis that intersects, particularly orthogonally, with the detection axis of the acceleration detection element 32a and the fourth rotation axis J4. That is to say, the inertial sensor 3 can detect the angular velocity around two axes that are orthogonal to the fourth rotation axis J4 and orthogonal to each other, and the acceleration in the directions of two axes that are orthogonal to the fourth rotation axis J4 and orthogonal to each other. According to such a structure, regardless of the orientation of the fourth joint 234, the angular velocity ωs can be detected based on the angular velocities detected by the angular velocity detection elements 31a and 31b, and the acceleration Azs can be detected based on the accelerations detected by the acceleration detection elements 32a and 32b.

[0100] In addition, as Figure 17 shown, the inertial sensor 3 is disposed on the fourth rotation axis J4 of the fourth arm 224. Therefore, regardless of the orientation of the fourth arm 224, the positional relationship between the second rotation axis J2, the third rotation axis J3, and the inertial sensor 3 remains unchanged. Therefore, the calculation of the angular velocity ωs and the acceleration Azs becomes easy.

[0101] As described above, the robot 2 of the present embodiment has a base 21, and the robotic arm 22 includes: a first arm 221 connected to the base 21 and rotatable relative to the base 21; a second arm 222 connected to the first arm 221 via a second joint 232; a third arm 223 connected to the second arm 222 via a third joint 233; and a fourth arm 224 connected to the third arm 223 and rotatable relative to the third arm 223 around a fourth rotation axis J4 that intersects the third rotation axis J3. And, an inertial sensor 3 is disposed on the fourth arm 224, and the inertial sensor 3 detects the angular velocity around two axes that intersect with the fourth rotation axis J4 and intersect with each other, and the acceleration in the directions of two axes that intersect with the fourth rotation axis J4 and intersect with each other. According to such a structure, regardless of the orientation of the fourth joint 234, the angular velocity ωs and the acceleration Azs can be detected. In addition, the inertial sensor 3 can be disposed to be further separated from the second rotation axis J2 and the third rotation axis J3, so that a larger acceleration Azs can be detected. Therefore, the vibration amounts of the joints of the second joint 232 and the third joint 233 can be discriminated with higher accuracy.

[0102] In addition, as described above, the inertial sensor 3 is located on the fourth rotation axis J4 which is the rotation axis of the fourth arm 224. Therefore, regardless of the orientation of the fourth arm 224, the positional relationship among the second rotation axis J2, the third rotation axis J3, and the inertial sensor 3 remains unchanged. As a result, the calculation of the angular velocity ωs and the acceleration Azs becomes easier.

[0103] According to such a second embodiment, the same effects as those of the above-described first embodiment can also be achieved.

[0104] Third Embodiment

[0105] Figure 18 is a schematic diagram showing the robot according to the third embodiment.

[0106] The robot system 1 according to the present embodiment is the same as the robot system 1 of the above-described first embodiment except for the structure of the inertial sensor 3. It should be noted that in the following description, regarding the robot system 1 of the present embodiment, the description will be centered on the differences from the above-described first embodiment, and the description of the same matters will be omitted. In addition, in the drawings of the present embodiment, the same reference numerals are given to the same structures as those of the above-described embodiments.

[0107] For example, as Figure 9 shown, in the case of the posture where the second arm 222 and the third arm 223 are orthogonal, the acceleration Azs generated by the vibration of the second joint 232 becomes smaller, and the translational velocity Vzs also becomes smaller. Therefore, there is a risk that the vibration amounts of the joints of the second joint 232 and the third joint 233 cannot be accurately discriminated.

[0108] Therefore, as Figure 18 shown, the inertial sensor 3 of the present embodiment includes, in addition to the acceleration detection element 32a, an acceleration detection element 32b having a detection axis that intersects, particularly orthogonally, with the detection axis of the acceleration detection element 32a and the second rotation axis J2 and the third rotation axis J3. According to such a structure, the detection axis of the acceleration detection element 32a is substantially aligned with the direction of the acceleration generated by the vibration of the second joint 232, and a larger acceleration can be detected by the acceleration detection element 32b. Therefore, the vibration amounts of the joints of the second joint 232 and the third joint 233 can be accurately discriminated.

[0109] It should be noted that in the case of Figure 18 , the translational velocity Vzs in the vertical direction of the inertial sensor 3 is determined by It is shown that the translational velocity Vxs in the horizontal direction is represented by Vxs = L2 × ω2. Therefore, the following equation (7) holds. Moreover, based on the values of the angular velocities ω2 and ω3 obtained through a pseudo-inverse matrix or the like according to equation (7), it is possible to determine the vibration amounts of the joints of the second joint 232 and the third joint 233, respectively.

[0110] Equation 7

[0111]

[0112] According to such a third embodiment, the same effects as those of the above-described first embodiment can also be achieved.

[0113] Fourth Embodiment

[0114] Figure 19 FIG. is a schematic diagram showing a robot according to the fourth embodiment.

[0115] The robot system 1 according to the present embodiment is the same as the robot system 1 of the above-described first embodiment except for the structure of the inertial sensor 3. It should be noted that in the following description, regarding the robot system 1 of the present embodiment, the differences from the above-described first embodiment will be mainly described, and the description of the same matters will be omitted. In addition, in the drawings of the present embodiment, the same reference numerals are assigned to the same structures as those in the above-described embodiments.

[0116] In the robot system 1 of the present embodiment, the inertial sensor 3 is configured to be able to detect the vibration of the first joint 231 about the first rotation axis J1. Specifically, as Figure 19 shown, the inertial sensor 3 of the present embodiment includes, in addition to the angular velocity detection element 31a, angular velocity detection elements 31c and 31d having detection axes that cross, particularly are orthogonal to, cross each other, particularly are orthogonal to the detection axis of the angular velocity detection element 31a. With such a structure, regardless of the orientations of the second joint 232 and the third joint 233, it is possible to detect the vibration of the first joint 231 about the first rotation axis J1 based on the angular velocities detected by the angular velocity detection elements 31c and 31d. It should be noted that, for the sake of simplicity of explanation, the acceleration detection element 32a is not shown.

[0117] According to such a fourth embodiment, the same effects as those of the above-described first embodiment can also be achieved.

[0118] Fifth Embodiment

[0119] Figure 20 FIG. is a schematic diagram showing a robot according to the fifth embodiment.

[0120] The robot system 1 according to this embodiment is the same as the robot system 1 of the above-described first embodiment, except for the structure of the robot 2 and the arrangement of the corresponding inertial sensors 3. It should be noted that in the following description, regarding the robot system 1 of this embodiment, the description will focus on the differences from the above-described first embodiment, and the description of the same matters will be omitted. In addition, in the drawings of this embodiment, the same reference numerals are given to the same structures as those in the above-described embodiment.

[0121] As Figure 20 shown, the robot 2 of this embodiment is a seven-axis vertical articulated robot having seven drive axes. In addition, the robotic arm 22 is configured such that the first arm 221, the second arm 222, the third arm 223, the fourth arm 224, the fifth arm 225, the sixth arm 226, and the seventh arm 227 are connected via the first joint 231, the second joint 232, the third joint 233, the fourth joint 234, the fifth joint 235, the sixth joint 236, and the seventh joint 237.

[0122] Specifically, the first arm 221 is rotatably connected to the base 21 about the first rotation axis J1 via the first joint 231. In addition, the second arm 222 is rotatably connected to the first arm 221 about the second rotation axis J2 via the second joint 232. In addition, the third arm 223 is rotatably connected to the second arm 222 about the third rotation axis J3 via the third joint 233. In addition, the fourth arm 224 is rotatably connected to the third arm 223 about the fourth rotation axis J4 via the fourth joint 234. In addition, the fifth arm 225 is rotatably connected to the fourth arm 224 about the fifth rotation axis J5 via the fifth joint 235. In addition, the sixth arm 226 is rotatably connected to the fifth arm 225 about the sixth rotation axis J6 via the sixth joint 236. In addition, the seventh arm 227 is rotatably connected to the sixth arm 226 about the seventh rotation axis J7 via the seventh joint 237.

[0123] In addition, among the first joint 231, the second joint 232, the third joint 233, the fourth joint 234, the fifth joint 235, the sixth joint 236, and the seventh joint 237, the second joint 232, the fourth joint 234, and the sixth joint 236 are respectively bending joints, and the first joint 231, the third joint 233, the fifth joint 235, and the seventh joint 237 are respectively twisting joints. In addition, the second rotation axis J2 is orthogonal to the first rotation axis J1, the third rotation axis J3 is orthogonal to the second rotation axis J2, the fourth rotation axis J4 is orthogonal to the third rotation axis J3, the fifth rotation axis J5 is orthogonal to the fourth rotation axis J4, the sixth rotation axis J6 is orthogonal to the fifth rotation axis J5, and the seventh rotation axis J7 is orthogonal to the sixth rotation axis J6.

[0124] In addition, an inertial sensor 3 is disposed on the third arm 223. The inertial sensor 3 can detect the angular velocity ωs about an axis parallel to the third rotation axis J3 and the acceleration Axs in a direction orthogonal to the third rotation axis J3.

[0125] In such a robot 2, the first joint 231 is the "base-end side joint" of the present application, and the third joint 233 is the "tip-end side joint" of the present application. That is, in the robot 2, the second joint 232 is located between the base-end side joint and the tip-end side joint. In the robot 2, as Figure 20 shown, when the second joint 232 is in a predetermined orientation, the first rotation axis J1 of the first joint 231 as the base-end side joint is parallel to the third rotation axis J3 of the third joint 233 as the tip-end side joint. Therefore, by the same method as in the above-described first embodiment, the vibration amounts of the joints of the first joint 231 and the third joint 233 can be detected.

[0126] Through such a fifth embodiment, the same effects as those of the above-described first embodiment can also be achieved.

[0127] Sixth Embodiment

[0128] Figure 21 FIG. is a diagram showing a robot according to the sixth embodiment.

[0129] The robot system 1 according to the present embodiment is the same as the robot system 1 of the above-described first embodiment except for the structure of the robot 5 and the arrangement of the corresponding inertial sensor 3. It should be noted that in the following description, the robot system 1 of the present embodiment will be described centering on the differences from the above-described first embodiment, and the description of the same matters will be omitted. In addition, in the drawings of the present embodiment, the same reference numerals are given to the same structures as those of the above-described embodiments.

[0130] As Figure 21 shown, the robot 5 of the present embodiment is a horizontal multi-joint robot (SCARA robot). Such a robot 5 has a base 51 and a robotic arm 52 connected to the base 51. In addition, the robotic arm 52 has a structure in which a first arm 521 and a second arm 522 are connected via a first joint 541 and a second joint 542.

[0131] The first arm 521 is rotatably connected to the base 21 about a first rotation axis J11 via the first joint 541. In addition, the second arm 522 is rotatably connected to the first arm 521 about a second rotation axis J12 via the second joint 542. In addition, these first joint 541 and second joint 542 are respectively torsion joints, and the first rotation axis J11 and the second rotation axis J12 are parallel and are along the vertical direction to each other.

[0132] Further, an operation head 53 is provided at the distal end portion of the second arm 522. The operation head 53 includes a spline nut 531 and a ball screw nut 532, which are coaxially arranged at the distal end portion of the second arm 522; and a spline shaft 533, which is inserted through the spline nut 531 and the ball screw nut 532 and serves as the main axis. The spline shaft 533 is rotatable relative to the second arm 522 about a third rotation axis J13 that is its central axis and along the vertical direction, and is movable (liftable and lowerable) along the third rotation axis J13. In addition, a mounting portion 533a for mounting an end effector (not shown) is provided at the lower end portion of the spline shaft 533. The end effector is detachable from and attachable to the mounting portion 533a, and an end effector suitable for the target operation is appropriately selected. It should be noted that the third rotation axis J13 is along the vertical direction and is parallel to the first rotation axis J11 and the second rotation axis J12.

[0133] In such a robot 5, the first joint 541 is the "base end side joint" of the present application, and the second joint 542 is the "distal end side joint" of the present application.

[0134] In addition, each of the joints 541, 542 includes a motor M, a speed reducer (not shown) that reduces the rotational speed of the motor M and outputs it, and an encoder E that detects the rotational amount of the motor M.

[0135] In addition, as Figure 21 shown, the inertial sensor 3 is disposed on the second arm 522. In addition, the inertial sensor 3 includes an angular velocity detection element 31a that detects the angular velocity ωs about an axis in the same direction as the first rotation axis J11 and the second rotation axis J12; and an acceleration detection element 32a that detects the acceleration Axs in a direction orthogonal to the first rotation axis J11 and the second rotation axis J12.

[0136] In the robot system 1 having such a structure, the vibration amounts of the joints of the first joint 541 and the second joint 542 can also be detected by the same method as in the above-described first embodiment.

[0137] According to such a sixth embodiment, the same effects as those of the above-described first embodiment can also be achieved.

[0138] As described above, the illustrated embodiments of the control method of the robot and the robot system of the present invention have been described, but the present invention is not limited thereto, and the structures and processes of each part can be replaced with any structures and processes having the same functions. In addition, other arbitrary structures and processes can be added to the present invention. In addition, the embodiments can be appropriately combined.

Claims

1. A robot control method, characterized in that: The robot control method is performed in a robot system, The robot system has: A robot, comprising a mechanical arm, wherein the mechanical arm has a base end joint and a terminal end joint, wherein the base end joint and the terminal end joint have rotation axes parallel to each other, and the terminal end joint is located at the terminal side of the base end joint; as well as an inertial sensor disposed on the robot arm closer to the distal end than the distal end joint and detecting an angular velocity around an axis parallel to the rotation axis and an acceleration in a direction intersecting the rotation axis, The control method of the robot comprises: An inertial information acquisition step of acquiring the angular velocity and the acceleration from the inertial sensor; a vibration detection step of detecting a vibration amount of each of the base end side joint and the tip end side joint based on the angular velocity and the acceleration acquired in the inertial information acquisition step; and The drive control step controls the vibration based on the vibration amount detected in the vibration detection step.

2. A robot system, characterized in that: have: A robot, comprising a mechanical arm, wherein the mechanical arm has a base end joint and a terminal end joint, wherein the base end joint and the terminal end joint have rotation axes parallel to each other, and the terminal end joint is located at the terminal side of the base end joint; an inertial sensor disposed on the robot arm closer to the distal end than the distal end joint and detecting an angular velocity around an axis parallel to the rotation axis and an acceleration in a direction intersecting the rotation axis; as well as The control device detects the vibration amount of each of the base end side joint and the distal end side joint based on the angular velocity and the acceleration detected by the inertial sensor, and controls vibration based on the detected vibration amount.

3. The robot system according to claim 2, wherein: The control device detects the vibration amount of each joint of the base side joint and the distal side joint based on the separation distance between the rotation axis of the base side joint and the rotation axis of the distal side joint and the separation distance between the rotation axis of the distal side joint and the inertial sensor.

4. The robot system according to claim 2, wherein: The robot has a base, The robot arm comprises: a first arm connected to the base and rotating relative to the base; a second arm connected to the first arm via the base end side joint; and a third arm connected to the second arm via the tip end side joint. The inertial sensor is disposed on the third arm.

5. The robot system according to claim 4, wherein: The inertial sensor is located on the central axis of the third arm when viewed in plan from a direction perpendicular to the rotation axis and the central axis of the third arm.

6. The robot system according to claim 4, wherein: The inertial sensor is disposed at an end portion of the third arm on the opposite side to the distal joint.

7. The robot system according to claim 4, wherein: The robot has a driving source, which is arranged in the third arm and is used to drive the robot arm. The inertial sensor is arranged separately from the driving source.

8. The robot system according to claim 4, wherein: The inertial sensor is disposed in the third arm.

9. The robot system according to claim 4, wherein: The inertial sensor is disposed on a wall portion of the third arm.

10. The robot system according to claim 9, wherein: The wall portion has an inner wall, an outer wall, and a hollow portion between the inner wall and the outer wall. The inertial sensor is disposed in the hollow portion.

11. The robot system according to claim 2, wherein: The robot has a base, The robot arm comprises: a first arm connected to the base and rotating relative to the base; a second arm connected to the first arm via the base end side joint; A third arm connected to the second arm via the distal side joint; and a fourth arm connected to the third arm and rotating relative to the third arm around a rotation axis intersecting the rotation axis, The inertial sensor is arranged on the fourth arm, The inertial sensor detects angular velocities about two axes that intersect the rotation axis of the fourth arm and intersect each other, and accelerations in two axis directions that intersect the rotation axis of the fourth arm and intersect each other.

12. The robot system according to claim 11, wherein: The inertial sensor is located on the rotation axis of the fourth arm.

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