Robot system

Abstract

To provide a robot system that can detect which joint is vibrating so as to control vibration effectively.SOLUTION: A robot system is provided with a robot which comprises a robot arm which includes a plurality of arms and a plurality of joints which include base end-side joints having turning shafts which are parallel to each other and tip-side joints positioned at tip sides of the base end-side joints, and inertial sensors arranged in the arms connecting the tip-side joints to the joints at one tip sides of the tip-side joints. The inertia sensors detect angular speed around shafts which are parallel to the turning shafts, and acceleration in a direction that is orthogonal to a center shaft of the arm in which the inertial sensor is arranged and also is orthogonal to the turning shaft.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a robot system.

Background Art

[0002] The manipulator described in Patent Document 1 includes an arm having a plurality of joints, an actuator disposed at each joint, an end effector connected to the tip of the arm, and an acceleration sensor disposed at the end effector. In such a manipulator, the vibration of the end effector is detected by the acceleration sensor, and the vibration is controlled based on the detection result.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the manipulator 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 control the vibration effectively.

Means for Solving the Problems

[0005] The robot system of the present invention includes a plurality of arms and a plurality of joints, and the plurality of joints include a base-end side joint having a rotation axis parallel to each other and a tip-end side joint located on the tip-end side of the base-end side joint, and a robot including a robot arm; an inertial sensor disposed on the arm connecting the tip-end side joint and the joint located on the tip-end side of one of the tip-end side joints. The inertial sensor detects an angular velocity about an axis parallel to the rotation axis and an acceleration in a direction orthogonal to the central axis of the arm on which the inertial sensor is disposed and orthogonal to the rotation axis.

[0006] The robot system of the present invention includes a plurality of arms and a plurality of joints, and the plurality of joints include a base-end side joint having a rotation axis parallel to each other and a tip-end side joint located on the tip-end side of the base-end side joint, and a robot including a robot arm. and an inertial sensor disposed on the arm that connects the joint located one tip-end side of the tip-end side joint and the joint located one more tip-end side. The inertial sensor detects an angular velocity about an axis parallel to the rotation axis and an acceleration in a direction orthogonal to the central axis of the arm on which the inertial sensor is disposed and orthogonal to the rotation axis.

[0007] The robot system of the present invention includes a plurality of arms and a plurality of joints, and the plurality of joints include a base-end side joint having a rotation axis parallel to each other and a tip-end side joint located on the tip-end side of the base-end side joint, and a robot including a robot arm. and an inertial sensor disposed on the arm located between the tip-end side joint and the joint located at the most tip-end side. The inertial sensor detects an angular velocity about an axis parallel to the rotation axis and an acceleration in a direction orthogonal to the central axis of the arm on which the inertial sensor is disposed and orthogonal to the rotation axis.

Brief Description of the Drawings

[0008]

Figure 1

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, the robot system of the present invention will be described in detail based on the embodiments shown in the accompanying drawings.

[0010] <First Embodiment> FIG. 1 is an overall view of a robot system according to the first embodiment. FIG. 2 is a schematic diagram showing a posture in which the vibration amounts of the respective joints of the second and third joints cannot be detected only by acceleration. FIG. 3 is a schematic diagram showing a posture in which the vibration amounts of the respective joints of the second and third joints cannot be detected only by angular velocity. FIG. 4 is a flowchart showing the control process of the robot. FIGS. 5 to 10 are schematic diagrams for explaining the method of detecting the vibration amount of each of the second and third joints, respectively. FIG. 11 is a block diagram showing the configuration of a control unit included in the control device. FIGS. 12 to 15 are diagrams showing examples of the arrangement of the inertial sensors, respectively.

[0011] The robot system 1 shown in FIG. 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.

[0012] The robot 2 is a six-axis vertical articulated robot having six drive axes, and includes a base 21 and a robot arm 22 rotatably connected to the base 21. The robot arm 22 has a configuration in which first, second, third, fourth, fifth, and sixth arms 221, 222, 223, 224, 225, and 226 are connected via first, second, third, fourth, fifth, and sixth joints 231, 232, 233, 234, 235, and 236. Here, the joint located on the one tip side of the first joint 231 is the second joint 232, the joint located on the one tip side of the second joint 232 is the third joint 233, the joint located on the one tip side of the third joint 233 is the fourth joint 234, the joint located on the one tip side of the fourth joint 234 is the fifth joint 235, and the joint located on the one tip side of the fifth joint 235 is the sixth joint 236.

[0013] The first arm 221 is rotatably connected to the base 21 about a first rotation axis J1 via a first joint 231. Further, the second arm 222 is rotatably connected to the first arm 221 about a second rotation axis J2 via a second joint 232. Further, the third arm 223 is rotatably connected to the second arm 222 about a third rotation axis J3 via a third joint 233. Further, the fourth arm 224 is rotatably connected to the third arm 223 about a fourth rotation axis J4 via a fourth joint 234. Further, the fifth arm 225 is rotatably connected to the fourth arm 224 about a fifth rotation axis J5 via a fifth joint 235. Further, the sixth arm 226 is rotatably connected to the fifth arm 225 about a sixth rotation axis J6 via a sixth joint 236.

[0014] Among the joints 231, 232, 233, 234, 235, 236, the second, third, and fifth joints 232, 233, 235 are bending joints, respectively, and the first, fourth, and sixth joints 231, 234, 236 are torsion joints, respectively. Further, 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. Further, the second, third, and fifth rotation axes J2, J3, J5 are each oriented in the horizontal direction.

[0015] In the present specification, "parallel" means, in addition to the case where the axes of each other are parallel, a deviation that can be regarded as parallel in terms of common technical knowledge with respect to parallel, for example, a deviation that may occur due to the dimensional accuracy, assembly accuracy, etc. of the robot 2. Further, "orthogonal" means, in addition to the case where the axes of each other are orthogonal, a deviation that can be regarded as orthogonal in terms of common technical knowledge with respect to orthogonal, for example, a deviation that may occur due to the dimensional accuracy, assembly accuracy, etc. of the robot 2.

[0016] In such a robot 2, the second joint 232 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.

[0017] Further, each of the joints 231, 232, 233, 234, 235, 236 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 rotation amount of the motor M. The control device 4 controls the rotation amount of each of the joints 231, 232, 233, 234, 235, 236 by driving the motor M by servo control that feeds back the output of the encoder E.

[0018] Also, an end effector 24 is attached to the tip of the robot arm 22, that is, the sixth arm 226. The end effector 24 is detachable from the sixth arm 226, and an appropriate one according to the work content to be performed by the robot 2 is attached as appropriate.

[0019] Also, as shown in FIG. 1, 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 and third rotation axes J2, J3, and an acceleration detection element 32a that detects the acceleration Azs in a direction orthogonal to the central axis A of the third arm 223 and orthogonal to the second and third rotation axes J2, J3. The acceleration Azs is, in detail, the vertical acceleration generated by the turning motion of the third arm 223 generated by driving at least one of the second and third joints 232, 232. By disposing the inertial sensor 3 on the third arm 223, the detection axis of the angular velocity detection element 31a is maintained parallel to the second and third rotation axes J2, J3, and the detection axis of the acceleration detection element 32a is maintained orthogonal to the second and third rotation axes J2, J3 in any posture, so that the angular velocity ωs and the acceleration Azs can be detected more reliably.

[0020] As described above, since the inertial sensor 3 is disposed on the third arm 223, it can be said that the inertial sensor 3 is disposed on the arm located between the third joint 233, which is the tip-side joint, and the sixth joint 236, which is located on the most tip side. In other words, it can be said that the inertial sensor 6 is not disposed on the sixth arm 226. Thus, by disposing the inertial sensor 3 while avoiding the arm located at the very tip, the number of joints intervening between the inertial sensor 3 and the third joint 233 can be suppressed to be as small as possible. Therefore, it becomes easier to detect the angular velocity ωs and the acceleration Azs without being affected by the posture of the robot arm 22.

[0021] In the present embodiment, one sensor unit including the angular velocity detection element 31a and the acceleration detection element 32a is used as the inertial sensor 3, but the present invention is not limited to this, and a configuration 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 arranged may be used.

[0022] The control device 4 controls the driving of the robot 2. The control device 4 is composed of, for example, a computer, and includes a processor (CPU) that processes information, a memory communicably connected to the processor, and an external interface that connects to an external device. Various programs executable by the processor are stored in the memory, and the processor can read and execute the programs and the like stored in the memory.

[0023] The configuration of the robot system 1 has been described above. For example, when the inertial sensor 3 can only detect the acceleration Azs, as shown in FIG. 2, in the posture where the second and third arms 222 and 223 both extend in the horizontal direction, it is impossible to distinguish the angular velocity ω2 caused by the vibration of the second joint 232 from the angular velocity ω3 caused by the vibration of the third joint 233. Also, for example, when the inertial sensor 3 can only detect the angular velocity ωs, as shown in FIG. 3, in the posture where the second arm 222 faces the vertical direction and the third arm 223 faces the horizontal direction and they are orthogonal, it is impossible to distinguish the angular velocity ω2 caused by the vibration of the second joint 232 from the angular velocity ω3 caused by the vibration of the third joint 233. In contrast, in the robot system 1, the inertial sensor 3 can detect both the angular velocity ωs and the acceleration Azs, and based on the relationship between the angular velocity ωs and the acceleration Azs, it is possible to distinguish the vibration of the second joint 232 from the vibration of the third joint 233. The method will be described below.

[0024] As shown in FIG. 4, 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 amount of each 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 based on the vibration amount of each joint based on the detection result of the vibration detection step S2. Each of these steps S1 to S3 will be described in detail below.

[0025] - Inertial Information Acquisition Step S1 - 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.

[0026] - Vibration Detection Step S2 - In the vibration detection step S2, the control device 4 detects the vibration amount of each 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.

[0027] As an example, as shown in FIG. 5, 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. As described above, in this posture, only the acceleration Azs cannot detect the vibration amounts of the respective joints of the second joint 232 and the third joint 233. Also, as shown in the figure, let the separation distance between the second rotation axis J2 and the third rotation axis J3 be L2, and the separation distance between the third rotation axis J3 and the inertial sensor 3 be L3. In the case of FIG. 5, the translational velocity Vzs in the vertical direction of the inertial sensor 3 is represented by Vzs = L×ω. The translational velocity Vzs is calculated by integrating the acceleration Azs detected by the inertial sensor 3. Also, L is the separation distance between the rotation axis of the joint where vibration occurs and the inertial sensor 3, and ω is the angular velocity around the rotation axis of the joint where vibration occurs.

[0028] As shown in FIG. 6, when the second joint 232 vibrates at an angular velocity ω2, Vzs = (L2 + L3)×ω2 and ω = ω2. On the other hand, as shown in FIG. 7, when the third joint 233 vibrates at an angular velocity ω3, Vzs = L3×ω3 and ω = ω3. Thus, a difference occurs in the relationship between the translational velocity Vzs and the angular velocity ω between the case where the second joint 232 vibrates and the case where the third joint 233 vibrates. Specifically, Vzs / ω when the second joint 232 vibrates is larger than Vzs / ω 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 respective joints of the second joint 232 and the third joint 233 can be discriminated.

[0029] From the above relationships, the following equations (1) and (2) using the Jacobian matrix hold. Therefore, based on the previously measured L2, L3, 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, from the obtained values of the angular velocities ω2 and ω3, the vibration amounts of the respective joints of the second joint 232 and the third joint 233 can be discriminated.

[0030]

Equation

[0031]

Number

[0032] Also, as another example, as shown in FIG. 8, an example will be described in which the second arm 222 faces the vertical direction and the third arm 223 faces the horizontal direction, and the second and third arms 222 and 223 are orthogonal to each other. At this time, let the vertical separation distance from the center of the third arm 222 to the detection center of the acceleration detected by the inertial sensor 3 be Lsz. As described above, in this posture, only the angular velocity ωs cannot detect the vibration amounts of the respective joints of the second joint 232 and the third joint 233.

[0033] As shown in FIG. 9, when the second joint 232 vibrates at an angular velocity ω2, Vzs = L3×ω2 and ω = ω2. On the other hand, as shown in FIG. 10, when the third joint 233 vibrates at an angular velocity ω3, Vzs = √(L3 2 + Lsz 2 )×ω3 and ω = ω3. Thus, there is a difference in the relationship between the translational velocity Vzs and the angular velocity ω between the case where the second joint 232 vibrates and the case where 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 respective joints of the second joint 232 and the third joint 233 can be discriminated.

[0034] From the above relationships, the following equations (3) and (4) using the Jacobian matrix hold. Therefore, based on the previously measured 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, the angular velocities ω2 and ω3 can be obtained. Then, from the obtained values of the angular velocities ω2 and ω3, the vibration amounts of the respective joints of the second joint 232 and the third joint 233 can be discriminated.

[0035]

Number

[0036]

Number

[0037] As described above, for two typical postures in which only one of the angular velocity ωs and the acceleration Azs cannot determine the vibration amount of each of the second joint 232 and the third joint 233, of course, even when in postures other than these, based on the relationship between the angular velocity ωs and the acceleration Azs, the vibration amount of each of the second joint 232 and the third joint 233 can be determined.

[0038] In the robot 2, the following equations (5) and (6) using the Jacobian matrix J hold at any posture. The Jacobian matrix J indicates the position of the inertial sensor 3 and has different values according to the rotation amounts of the second and third joints 232 and 233. The position of the inertial sensor 3 is detected based on, for example, the outputs of the encoders E provided in the second and third joints 232 and 233. 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, based on the obtained values of the angular velocities ω2 and ω3, the vibration amount of each of the second joint 232 and the third joint 233 can be determined.

[0039]

Number

[0040]

Number

[0041] According to the method as described above, the vibration amount of each of the second joint 232 and the third joint 233 can be determined. In particular, based on the pre-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, the vibration amount of each of the second joint 232 and the third joint 233 can be determined, so that the detection can be easily performed.

[0042] -Drive control step S3- In the drive control step S3, the control device 4 controls the drive of the robot arm 22 based on the detection result of the vibration detection step S2. Specifically, the control device 4 performs control of the detected second joint 232 and the detected third joint 233 based on the vibration amount of each joint determined in the vibration detection step S2. In this way, by controlling the vibration based on the vibration amount of each joint, more appropriate control can be performed, and the vibration can be reduced more reliably and effectively.

[0043] For example, taking the control example for the second joint 232 as an example, as shown in FIG. 11, the control device 4 has a control unit 40 that controls the drive of the second joint 232. The control unit 40 includes 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.

[0044] The vibration feedback generation unit 45 multiplies the angular velocity ω of the vibration amount determined 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 by the arm angular velocity scaling coefficient Kgs to obtain the motor shaft conversion arm angular velocity 912. Further, the vibration feedback generation unit 45 obtains the motor shaft angular velocity 913 by differentiating with respect to time the motor shaft position 902, which is the rotation angle of the motor M detected by the encoder E. Next, the vibration feedback generation unit 45 subtracts the motor shaft angular velocity 913 from the motor shaft conversion arm angular velocity 912 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.

[0045] The position command generation unit 41 generates a position command 901 for the motor M based on a program created 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.

[0046] 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 obtains a current command 906 by adding an integral term obtained by multiplying the integral value of the speed loop command 905 by the speed loop integral gain Kvi to a proportional term obtained by multiplying the speed loop command 905 by the speed loop proportional gain Kvp.

[0047] The current control unit 44 controls so that the current 907 for driving the motor M matches the current command 906, that is, so that the current 907 follows the current command 906. Then, the motor M is driven by the current 907 controlled by the current control unit 44.

[0048] An example of control has been described above. Next, several examples of the arrangement of the inertial sensor 3 will be described. For example, as shown in FIG. 12, the inertial sensor 3 is located on the central axis A of the third arm 223 in a plan view from a direction perpendicular to the vertical direction, that is, the third rotation axis J3 and the central axis A of the third arm 223. In the case of the robot system 1, the central axis A is perpendicular 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. According to such an arrangement, the arrangement of the inertial sensor 3 becomes easy. Further, the inertial sensor 3 is arranged at the end on the side of the fourth joint 234, that is, the end on the side opposite to the third joint 233. Thereby, since the inertial sensor 3 can be arranged as far as possible away from the third rotation axis J3, a larger acceleration Azs can be detected. Here, another example of the central axis A of the arm is an axis that is parallel to the extending direction of the arm and passes through the center of gravity position of the arm. Also, the central axis A of the arm may be an axis that is parallel to the line segment connecting the center of gravity position of the joint to which the arm is connected on the tip side to the center of gravity position of the joint to which the arm is connected on the base end side. The inertial sensor 3 is arranged so as to acquire the acceleration Azs in the direction perpendicular to the central axis A of the installed arm, so that the acceleration generated by the turning motion of the arm caused by the driving of at least one of the base end side joint and the tip side joint can be accurately detected.

[0049] Also, for example, as shown in FIG. 13, when a motor M as a drive source is arranged in the third arm 223, the inertial sensor 3 is arranged away from the motor M. Thereby, it becomes difficult for the vibration generated by the driving of the motor M to be transmitted to the inertial sensor 3, and the angular velocity ωs and the acceleration Azs can be accurately detected by the inertial sensor 3. Note that the motor M arranged in the third arm 223 may be the motor M provided in any joint. For example, it may be the motor M provided in the third joint 233, or it may be the motor M provided in the fourth joint 234.

[0050] Also, for example, as shown in FIG. 14, the inertial sensor 3 is disposed within the third arm 223. Thereby, the inertial sensor 3 can be protected from moisture, dust, and the like. Further, 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 attached to the housing 223a, and the inertial sensor 3 is disposed on the wall portion of the cover 223b. Since a speed reducer and a motor M are fixed to the housing 223a, arranging the inertial sensor 3 on the cover 223b makes it difficult for vibrations generated from the speed reducer and the motor M to be transmitted to the inertial sensor 3. Therefore, the angular velocity ωs and the acceleration Azs can be accurately detected by the inertial sensor 3.

[0051] Also, for example, as shown in FIG. 15, 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. In this way, by accommodating the inertial sensor 3 within the cover 223b, the inertial sensor 3 can be protected from moisture, dust, and the like. Further, the inertial sensor 3 is disposed on the outer wall 223d. Thereby, it becomes difficult for vibrations generated from the speed reducer and the motor M to be transmitted to the inertial sensor 3. Therefore, the angular velocity ωs and the acceleration Azs can be accurately detected by the inertial sensor 3.

[0052] The robot system 1 has been described above. As described above, such a robot system 1 includes a plurality of arms, namely, the first, second, third, fourth, fifth, and sixth arms 221, 222, 223, 224, 225, 226, and a plurality of joints, namely, the first, second, third, fourth, fifth, and sixth joints 231, 232, 233, 234, 235, 236. The plurality of joints include a second joint 232, which is a base-end side joint having rotation axes J2 and J3 that are parallel to each other, and a third joint 233, which is a tip-end side joint located on the tip-end side of the second joint 232. The robot 2 includes a robot arm 22 having such a structure. The robot 2 also includes an inertial sensor 3 disposed on a third arm 223 that connects the third joint 233 and a fourth joint 234 located on the tip-end side of the third joint 233. The inertial sensor 3 detects an angular velocity ωs about an axis parallel to the second and third rotation axes J2 and J3, and an acceleration Azs in a direction orthogonal to the central axis A of the third arm 223 on which the inertial sensor 3 is disposed and also orthogonal to the second and third rotation axes J2 and J3. According to such a configuration, based on the relationship between the angular velocity ωs and the acceleration Azs detected by the inertial sensor 3, the vibration amounts of the respective joints of the second and third joints 232 and 233 can be detected. Then, by controlling the vibration based on the vibration amounts of the respective joints, the vibration of the robot arm 22 can be effectively reduced. In particular, by disposing the inertial sensor 3 on the third arm 223, the angular velocity ωs and the acceleration Azs can be detected regardless of the posture of the robot arm 22.

[0053] Also, as described above, the robot system 1 includes a plurality of arms, i.e., first, second, third, fourth, fifth, and sixth arms 221, 222, 223, 224, 225, 226, and a plurality of joints, i.e., first, second, third, fourth, fifth, and sixth joints 231, 232, 233, 234, 235, 236. The plurality of joints include a second joint 232 which is a base-end side joint having second and third rotation axes J2 and J3 that are rotation axes parallel to each other, and a third joint 233 which is a tip-end side joint located on the tip-end side of the second joint 232. The robot 2 includes a robot arm 22. An inertial sensor 3 is disposed on any one of the third, fourth, and fifth arms 223, 224, 225, which are arms located between the third joint 233 and the sixth joint 236 located at the most tip-end side. The inertial sensor 3 detects an angular velocity ωs about an axis parallel to the second and third rotation axes J2 and J3, and an acceleration Azs in a direction orthogonal to the central axis A of the arm on which the inertial sensor 3 is disposed and also orthogonal to the second and third rotation axes J2 and J3. According to such a configuration, based on the relationship between the angular velocity ωs and the acceleration Azs detected by the inertial sensor 3, the amount of vibration of each of the second and third joints 232 and 233 can be detected. Then, by controlling the vibration based on the amount of vibration of each joint, the vibration of the robot arm 22 can be effectively reduced. In particular, by arranging the inertial sensor 3 avoiding the sixth arm 226 located at the most tip-end, the number of joints intervening between the inertial sensor 3 and the third joint 233 can be suppressed to be as small as possible. Therefore, it becomes easier to detect the angular velocity ωs and the acceleration Azs without being affected by the posture of the robot arm 22.

[0054] Also, as described above, the robot 2 has a base 21, and the robot arm 22 is connected via a first joint 231 which is a joint different from the base-end side joint and the tip-end side joint, and different from the tip-end side joint, to a first arm 221, a second arm 222 connected to the first arm 221 via a second joint 232 which is a base-end side joint, and a third arm 223 connected to the second arm 222 via a third joint 233 which is a tip-end side joint. And an inertial sensor 3 is disposed on the third arm 223. According to such a configuration, in any posture of the robot arm 22, the detection axis of the angular velocity detection element 31a is maintained parallel to the second and third rotation axes J2, J3, and the detection axis of the acceleration detection element 32a is maintained orthogonal to the second and third rotation axes J2, J3, so that the angular velocity ωs and the acceleration Azs can be detected more reliably.

[0055] Also, as described above, the inertial sensor 3 is located on the central axis A of the third arm 223 in a plan view from a direction orthogonal to the second and third rotation axes J2, J3 and the central axis A of the third arm 223. According to such an arrangement, the arrangement of the inertial sensor 3 becomes easy.

[0056] Also, as described above, the inertial sensor 3 is disposed at an end of the third arm 223 opposite to the third joint 233. Thereby, the inertial sensor 3 can be arranged as far as possible from the third rotation axis J3, so that a larger acceleration Azs can be detected.

[0057] Also, as described above, the robot 2 has a motor M as a drive source disposed in the third arm 223 and driving the robot arm 22. And the inertial sensor 3 is disposed apart from the motor M. Thereby, vibration generated by driving of the motor M is less likely to be transmitted to the inertial sensor 3, and the angular velocity ωs and the acceleration Azs can be accurately detected by the inertial sensor 3.

[0058] Also, as described above, the inertial sensor 3 is disposed within the third arm 223. Thereby, the inertial sensor 3 can be protected from moisture, dust, and the like.

[0059] Also, as described above, the inertial sensor 3 is disposed on the cover 223b which is the wall portion of the third arm 223. Thereby, it becomes difficult for vibrations generated from the speed reducer or the motor M to be transmitted to the inertial sensor 3. Therefore, the angular velocity ωs and the acceleration Azs can be accurately detected by the inertial sensor 3.

[0060] Also, as described above, the cover 223b which is 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. And the inertial sensor 3 is disposed in the hollow portion 223e. Thereby, the inertial sensor 3 can be protected from moisture, dust, and the like.

[0061] <Second Embodiment> FIG. 16 is a schematic diagram showing a robot according to the second embodiment. FIG. 17 is a diagram showing the arrangement of the inertial sensors.

[0062] The robot system 1 according to the present embodiment is the same as the robot system 1 of the first embodiment described above, except that the configuration and arrangement of the inertial sensor 3 are different. 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. Also, in each figure of the present embodiment, the same components as those of the above-described embodiment are denoted by the same reference numerals.

[0063] As shown in FIG. 16, in the robot system 1 of the present embodiment, an inertial sensor 3 is disposed on the fourth arm 224. The inertial sensor 3 detects an acceleration Azs in a direction orthogonal to the central axis of the fourth arm 224 and orthogonal to the second and third rotation axes J2 and J3. By disposing the inertial sensor 3 on the fourth arm 224 in this way, the inertial sensor 3 can be disposed at a greater distance from the second and third rotation axes J2 and J3, so that a greater acceleration Azs can be detected. Therefore, the amount of vibration of each of the second joint 232 and the third joint 233 can be determined with higher accuracy.

[0064] In such a configuration, as the fourth joint 234 rotates, the detection axis of the inertial sensor 3 rotates with respect to the second and third rotation axes J2 and J3. Therefore, in a configuration having one angular velocity detection element 31a and one acceleration detection element 32a as in the inertial sensor 3 of the first embodiment described above, depending on the orientation of the fourth joint 234, the angular velocity ωs and the acceleration Azs cannot be detected.

[0065] Therefore, the inertial sensor 3 of the present embodiment includes, in addition to the angular velocity detection element 31a, an angular velocity detection element 31b having a detection axis orthogonal to the detection axis of the angular velocity detection element 31a and the fourth rotation axis J4. Further, 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 orthogonal to the detection axis of the acceleration detection element 32a and the fourth rotation axis J4. That is, the inertial sensor 3 can detect the angular velocity about two axes orthogonal to the fourth rotation axis J4 and orthogonal to each other, and the acceleration in two axial directions orthogonal to the fourth rotation axis J4 and orthogonal to each other. According to such a configuration, 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.

[0066] Also, as shown in FIG. 17, 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 and third rotation axes J2, J3 and the inertial sensor 3 is kept constant. Thus, the calculation of the angular velocity ωs and the acceleration Azs becomes easy.

[0067] As described above, the robot system 1 of the present embodiment includes a first, second, third, fourth, fifth, and sixth arm 221, 222, 223, 224, 225, 226 which are a plurality of arms, and a first, second, third, fourth, fifth, and sixth joint 231, 232, 233, 234, 235, 236 which are a plurality of joints. The plurality of joints include a second joint 232 which is a base-end side joint having second and third rotation axes J2, J3 which are rotation axes parallel to each other, and a third joint 233 which is a tip-end side joint located on the tip-end side of the second joint 232. The robot 2 includes a robot arm 22, an inertial sensor 3 disposed on a fourth arm 224 connecting a fourth joint 234 which is a joint located on one tip-end side of the third joint 233 and a fifth joint 235 which is a joint located on a further tip-end side. The inertial sensor 3 detects an angular velocity ωs about an axis parallel to the second and third rotation axes J2, J3, and an acceleration Azs in a direction orthogonal to the central axis of the fourth arm 224 on which the inertial sensor 3 is disposed and orthogonal to the second and third rotation axes J2, J3. According to such a configuration, based on the relationship between the angular velocity ωs and the acceleration Azs detected by the inertial sensor 3, the vibration amount of each of the second and third joints 232, 233 can be detected. Then, by controlling the vibration based on the vibration amount of each joint, the vibration of the robot arm 22 can be effectively reduced. In particular, by disposing the inertial sensor 3 on the fourth arm 224, the inertial sensor 3 can be disposed at a greater distance from the second and third rotation axes J2, J3, so that a greater acceleration Azs can be detected. Therefore, the vibration amount of each of the second and third joints 232, 233 can be determined more accurately.

[0068] Also, as described above, the robot 2 has a base 21, and the robot arm 22 is connected via a first joint 231 which is a joint different from the base-end side joint and also different from the tip-end side joint with respect to the base 21. The robot arm 22 includes a first arm 221, a second arm 222 connected to the first arm 221 via a second joint 232 which is a base-end side joint, a third arm 223 connected to the second arm 222 via a third joint 233 which is a tip-end side joint, and a fourth arm 224 connected to the third arm 223 via a fourth joint 234 which is a joint different from the base-end side joint and also different from the tip-end side joint. An inertial sensor 3 is disposed on the fourth arm 224, and the inertial sensor 3 detects angular velocities about two axes orthogonal to each other and orthogonal to the fourth rotation axis J4, and accelerations in two axial directions orthogonal to each other and orthogonal to the fourth rotation axis J4. According to such a configuration, the angular velocity ωs and the acceleration Azs can be detected regardless of the orientation of the fourth joint 234. Further, since the inertial sensor 3 can be disposed at a greater distance from the second and third rotation axes J2 and J3, a greater acceleration Azs can be detected. Therefore, the amount of vibration of each of the second and third joints 232 and 233 can be determined with higher accuracy.

[0069] Also, 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 between the second and third rotation axes J2 and J3 and the inertial sensor 3 is kept constant. Thus, the calculation of the angular velocity ωs and the acceleration Azs becomes easy.

[0070] Also by such a second embodiment, the same effects as those of the first embodiment described above can be exhibited.

[0071] <Third Embodiment> FIG. 18 is a schematic diagram showing a robot according to the third embodiment.

[0072] The robot system 1 according to this embodiment is the same as the robot system 1 of the first embodiment described above, except that the configuration of the inertial sensor 3 is different. In the following description, regarding the robot system 1 of this embodiment, the differences from the first embodiment described above will be mainly described, and the description of the same matters will be omitted. Also, in the drawings of this embodiment, the same reference numerals are given to the configurations that are the same as those of the above-described embodiments.

[0073] For example, in the case of the posture where the second and third arms 222 and 223 are orthogonal as shown in FIG. 9, the acceleration Azs generated by the vibration of the second joint 232 is small, and the translational speed Vzs is also small. Therefore, there is a possibility that the vibration amounts of the respective joints of the second joint 232 and the third joint 233 cannot be accurately determined.

[0074] Therefore, as shown in FIG. 18, the inertial sensor 3 of this embodiment includes, in addition to the acceleration detection element 32a, an acceleration detection element 32b having a detection axis orthogonal to the detection axis of the acceleration detection element 32a and the second and third rotation axes J2 and J3. According to such a configuration, the detection axis of the acceleration detection element 32a substantially coincides 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 respective joints of the second joint 232 and the third joint 233 can be accurately determined.

[0075] In the case of FIG. 18, the translational speed Vzs in the vertical direction of the inertial sensor 3 is Vzs = L2×ω2 + √(L3 2 + Lsz 2 )×ω3, and the translational speed Vxs in the horizontal direction is represented by Vxs = L2×ω2. Therefore, the following equation (7) holds. And from the values of the angular velocities ω2 and ω3 obtained by equation (7), the vibration amounts of the respective joints of the second joint 232 and the third joint 233 can be determined.

[0076]

Equation

[0077] Even with such a third embodiment, the same effects as those of the first embodiment described above can be achieved.

[0078] <Fourth Embodiment> FIG. 19 is a schematic diagram showing a robot according to the fourth embodiment.

[0079] The robot system 1 according to this embodiment is the same as the robot system 1 of the first embodiment described above, except that the configuration of the inertial sensor 3 is different. In the following description, regarding the robot system 1 of this embodiment, the differences from the first embodiment described above will be mainly described, and the description of the same matters will be omitted. Also, in the drawings of this embodiment, the same reference numerals are given to the same configurations as those of the above-described embodiments.

[0080] In the robot system 1 of this embodiment, the inertial sensor 3 is configured to be able to detect vibrations around the first rotation axis J1 of the first joint 231. Specifically, as shown in FIG. 19, the inertial sensor 3 of this embodiment includes, in addition to the angular velocity detection element 31a, angular velocity detection elements 31c and 31d that are orthogonal to the detection axis of the angular velocity detection element 31a and have detection axes orthogonal to each other. According to such a configuration, regardless of the orientations of the second and third joints 232 and 233, vibrations around the first rotation axis J1 of the first joint 231 can be detected based on the angular velocities detected by the angular velocity detection elements 31c and 31d. For the sake of convenience of explanation, the acceleration detection element 32a is not shown.

[0081] Even with such a fourth embodiment, the same effects as those of the first embodiment described above can be achieved.

[0082] <Fifth Embodiment> FIG. 20 is a schematic diagram showing a robot according to the fifth embodiment.

[0083] The robot system 1 according to this embodiment is the same as the robot system 1 of the first embodiment described above, except that the configuration of the robot 2 and the arrangement of the inertial sensor 3 corresponding thereto are different. In the following description, regarding the robot system 1 of this embodiment, the description will focus on the differences from the first embodiment described above, and the description of the same matters will be omitted. Also, in the drawings of this embodiment, the same reference numerals are given to the configurations that are the same as those of the above-described embodiments.

[0084] As shown in FIG. 20, the robot 2 of this embodiment is a 7-axis vertical articulated robot having seven drive axes. Also, the robot arm 22 has a configuration in which the first, second, third, fourth, fifth, sixth, and seventh arms 221, 222, 223, 224, 225, 226, and 227 are connected via the first, second, third, fourth, fifth, sixth, and seventh joints 231, 232, 233, 234, 235, 236, and 237.

[0085] Specifically, the first arm 221 is rotatably connected to the base 21 via the first joint 231 about the first rotation axis J1. Also, the second arm 222 is rotatably connected to the first arm 221 via the second joint 232 about the second rotation axis J2. Also, the third arm 223 is rotatably connected to the second arm 222 via the third joint 233 about the third rotation axis J3. Also, the fourth arm 224 is rotatably connected to the third arm 223 via the fourth joint 234 about the fourth rotation axis J4. Also, the fifth arm 225 is rotatably connected to the fourth arm 224 via the fifth joint 235 about the fifth rotation axis J5. Also, the sixth arm 226 is rotatably connected to the fifth arm 225 via the sixth joint 236 about the sixth rotation axis J6. Also, the seventh arm 227 is rotatably connected to the sixth arm 226 via the seventh joint 237 about the seventh rotation axis J7.

[0086] Among the first, second, third, fourth, fifth, sixth, and seventh joints 231, 232, 233, 234, 235, 236, and 237, the second, fourth, and sixth joints 232, 234, and 236 are bending joints, respectively, and the first, third, fifth, and seventh joints 231, 233, 235, and 237 are torsion joints, respectively. Also, 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. is.

[0087] Also, 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.

[0088] 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 shown in FIG. 20, when the second joint 232 is in a predetermined orientation, the first rotation axis J1 of the first joint 231, which is the base-end side joint, and the third rotation axis J3 of the third joint 233, which is the tip-end side joint, are parallel. Therefore, in the same manner as in the first embodiment described above, the vibration amounts of the respective joints of the first joint 231 and the third joint 233 can be detected.

[0089] As described above, the robot 2 of the present embodiment has a base 21. The robot arm 22 includes a first arm 221 connected to the base 21 via a first joint 231 which is a base-end side joint, and a second arm 222 connected to the first arm 221 via a second joint 232 which is a joint different from the base-end side joint and also different from the tip-end side joint, and a third arm 223 connected to the second arm 222 via a third joint 233 which is a tip-end side joint. An inertial sensor 3 is disposed on the third arm 223. According to such a configuration, when the second joint 232 is in a predetermined orientation, the first rotation axis J1 of the first joint 231 which is the base-end side joint and the third rotation axis J3 of the third joint 233 which is the tip-end side joint are parallel, and the vibration amounts of the respective joints of the first and third joints 231 and 233 can be detected.

[0090] Even with such a fifth embodiment, the same effects as those of the first embodiment described above can be achieved.

[0091] <Sixth Embodiment> FIG. 21 is a diagram showing a robot according to the sixth embodiment.

[0092] The robot system 1 according to the present embodiment is the same as the robot system 1 of the first embodiment described above, except that the configuration of the robot 5 and the arrangement of the inertial sensor 3 corresponding thereto are different. 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. Also, in the drawings of the present embodiment, the same reference numerals are given to the same configurations as those of the above-described embodiments.

[0093] As shown in FIG. 21, the robot 5 of the present embodiment is a horizontal articulated robot (scalar robot). Such a robot 5 has a base 51 and a robot arm 52 connected to the base 51. The robot arm 52 has a configuration in which the first and second arms 521 and 522 are connected via the first and second joints 541 and 542.

[0094] The first arm 521 is rotatably connected to the base 21 about a first rotation axis J11 via a first joint 541. Further, the second arm 522 is rotatably connected to the first arm 521 about a second rotation axis J12 via a second joint 542. Moreover, these first and second joints 541 and 542 are torsion joints respectively, and the first and second rotation axes J11 and J12 are parallel and along the vertical direction to each other.

[0095] Further, a working head 53 is provided at the tip of the second arm 522. The working head 53 includes a spline nut 531 and a ball screw nut 532 coaxially arranged at the tip of the second arm 522, and a spline shaft 533 which is a main shaft inserted through the spline nut 531 and the ball screw nut 532. The spline shaft 533 is rotatable about a third rotation axis J13 which is its central axis and along the vertical direction with respect to the second arm 522, 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 of the spline shaft 533. The end effector is detachable from the mounting portion 533a, and an appropriate one suitable for the target work is selected as appropriate. Note that the third rotation axis J13 is along the vertical direction and is parallel to the first and second rotation axes J11 and J12.

[0096] 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 "tip end side joint" of the present application.

[0097] Moreover, each of the joints 541 and 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 rotation amount of the motor M.

[0098] Also, as shown in FIG. 21, the inertial sensor 3 is disposed on the second arm 522. The inertial sensor 3 includes an angular velocity detection element 31a that detects an angular velocity ωs about an axis in the same direction as the first and second rotation axes J11 and J12, and an acceleration detection element 32a that detects an acceleration Axs in a direction orthogonal to the first and second rotation axes J11 and J12.

[0099] Even in the robot system 1 having such a configuration, the vibration amounts of the respective joints of the first joint 541 and the second joint 542 can be detected in the same manner as in the first embodiment described above.

[0100] Also, according to such a sixth embodiment, the same effects as those of the first embodiment described above can be exhibited.

[0101] As described above, the control method and the robot system of the present invention have been described with respect to the illustrated embodiments. However, the present invention is not limited thereto, and the configuration and process of each part can be replaced with any configuration and process having the same function. Further, any other arbitrary configuration and process may be added to the present invention. Also, the respective embodiments may be appropriately combined.

Description of Reference Numerals

[0102] 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…Velocity 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…Velocity command, 905…Velocity 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 coefficient, Kpp…Position loop proportional gain, Kvi…Velocity loop integral gain, Kvp…Velocity 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 velocity, Vzs…Translation velocity, ω…Angular velocity, ω2…Angular velocity, ω3…Angular velocity, ωs…Angular velocity

Claims

1. A robot comprising a plurality of arms and a plurality of joints, wherein the plurality of joints include a base-end joint having a rotation axis parallel to each other and a tip-end joint located on the tip-end side of the base-end joint, and a robot arm; An inertial sensor disposed on the arm connecting the tip-end joint and the joint located one tip-end side of the tip-end joint; and having The inertial sensor is characterized in that it detects an angular velocity about an axis parallel to the rotation axis and an acceleration in a direction orthogonal to the central axis of the arm on which the inertial sensor is disposed and orthogonal to the rotation axis. A robot system.

2. A robot comprising a plurality of arms and a plurality of joints, wherein the plurality of joints include a base-end joint having a rotation axis parallel to each other and a tip-end joint located on the tip-end side of the base-end joint, and a robot arm; An inertial sensor disposed on the arm connecting the joint located one tip-end side of the tip-end joint and the joint located further one tip-end side; and having The inertial sensor is characterized in that it detects an angular velocity about an axis parallel to the rotation axis and an acceleration in a direction orthogonal to the central axis of the arm on which the inertial sensor is disposed and orthogonal to the rotation axis. A robot system.

3. A robot comprising a plurality of arms and a plurality of joints, wherein the plurality of joints include a base-end joint having a rotation axis parallel to each other and a tip-end joint located on the tip-end side of the base-end joint, and a robot arm; An inertial sensor disposed on the arm located between the tip-end joint and the joint located at the most tip-end side; and having The inertial sensor is characterized in that it detects an angular velocity about an axis parallel to the rotation axis and an acceleration in a direction orthogonal to the central axis of the arm on which the inertial sensor is disposed and orthogonal to the rotation axis. A robot system.

4. The robot has a base; The robot arm includes a first arm connected to the base via a joint different from the base-end joint and different from the tip-end joint, a second arm connected to the first arm via the base-end joint, and a second arm connected to the second arm via the tip-end joint. And a third arm; The robot system according to claim 1 or 3, wherein 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 in a plan view from a direction orthogonal 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 of the third arm opposite to the distal joint.

7. The robot has a drive source disposed within the third arm for driving the robot arm, The robot system according to claim 4, wherein the inertial sensor is disposed at a distance from the drive source.

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

9. The robot system according to claim 8, wherein the inertial sensor is disposed on a wall portion of the third arm.

10. The wall portion has an inner wall, an outer wall, and a hollow portion located between the inner wall and the outer wall, The robot system according to claim 8, wherein the inertial sensor is disposed in the hollow portion.

11. The robot has a base, The robot arm includes a first arm connected to the base via a joint different from the proximal joint and the distal joint, a second arm connected to the first arm via the proximal joint, a third arm connected to the second arm via the distal joint, and a fourth arm connected to the third arm via a joint different from the proximal joint and the distal joint, The inertial sensor is disposed on the fourth arm, The robot system according to claim 2, wherein the inertial sensor detects angular velocities about two axes orthogonal to the rotation axis of the fourth arm and orthogonal to each other, and accelerations in two axial directions orthogonal to the rotation axis of the fourth arm and orthogonal to each other.

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

13. The robot has a base, The robot arm includes a first arm connected to the base via the proximal joint, a second arm connected to the first arm via a joint different from the proximal joint and the distal joint, and a third arm connected to the second arm via the distal joint. The robot system according to claim 1 or 2, wherein the inertial sensor is disposed on the third arm.

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