Robot system and method for controlling the robot system

Abstract

This invention provides a robot system and a control method for the robot system that can avoid the acquisition of underestimated external force values. [Solution] This robot system 100 includes a robot 10 with multiple joints 13, a torque detection unit 14 positioned at a predetermined joint 13 among the multiple joints 13 and detecting a torque value around the rotation axis of the predetermined joint 13, and a value P obtained by dividing the difference between the detected torque value and the reference torque value by the radius R from the rotation axis of the predetermined joint 13 to a monitoring point 40 set on the surface of the robot 10. i This value, Pa, is converted to a normal value based on the angle θ between the tangential direction at the monitoring point 40 of a circle with radius R and the normal direction to the surface of the robot 10 on which the monitoring point 40 is set. i The system includes a control unit 20 that performs control to acquire the external force value acting on the robot 10.

Description

Technical Field

[0001] This disclosure relates to a robot system and a method for controlling a robot system.

Background Art

[0002] Conventionally, a robot system has been known (see, for example, Patent Document 1).

[0003] <0000,072>Patent Document 1 discloses a robot system including a robot and a control device that controls the robot. The robot is a vertically articulated robot, and torque sensors for detecting torque around the rotation axis of the joints are provided at the first to third joints from the base end side. The control device is configured to obtain, as an external force value, a value obtained by dividing the difference torque between the torque detected by the torque sensor and the calculated torque calculated from the posture and operation of the robot by the minimum radius from the rotation axis of the joint at a physically contactable position.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the robot system described in Patent Document 1, since the value obtained by dividing the difference torque by the minimum radius is used as the external force value, only the force in the tangential direction of the circle having the minimum radius is considered, and the force in the radial direction is ignored. In this case, there is a problem that the external force value is obtained to be smaller.

[0006] This disclosure has been made to solve the above problems, and it is an object thereof to provide a robot system and a method for controlling a robot system capable of avoiding obtaining an external force value that is too small.

Means for Solving the Problem

[0007] A robot system according to a first aspect of this disclosure includes a robot including a plurality of joints, a torque detection unit disposed at a predetermined joint among the plurality of joints and detecting a detected torque value around the rotation axis of the predetermined joint, and a difference value between the detected torque value and a reference torque value is divided by a radius from the rotation axis of the predetermined joint to a monitoring point set on the surface of the robot, and a first value obtained thereby is converted into a value in the normal direction based on an angle formed by a tangential direction at the monitoring point of a circle having the radius and a normal direction with respect to the surface of the robot where the monitoring point is set, and a control unit that performs control to obtain an external force value acting on the robot as a second value. In the specification of the present application, the surface of the robot is a broad concept that includes, when the robot includes a hand that holds a workpiece, the surface of the robot's hand and the surface of the workpiece held by the robot's hand.

[0008] In the robot system according to the first aspect of this disclosure, as described above, a control unit is provided that performs control to obtain, as an external force value acting on the robot, a second value obtained by converting a first value obtained by dividing a difference value between the detected torque value and the reference torque value by a radius from the rotation axis of the predetermined joint to a monitoring point set on the surface of the robot into a value in the normal direction based on an angle formed by a tangential direction at the monitoring point of a circle having the radius and a normal direction with respect to the surface of the robot where the monitoring point is set. As a result, an external force value obtained by synthesizing the force in the tangential direction and the force in the radial direction at the monitoring point can be obtained, so that only the force in the tangential direction at the monitoring point is considered and the force in the radial direction at the monitoring point is not ignored. As a result, it is possible to avoid the external force value being obtained too small.

[0009] A control method for a robot system according to the second aspect of this disclosure is a control method for a robot system comprising a robot including a plurality of joints, comprising: detecting a detected torque value around the rotation axis of a predetermined joint among the plurality of joints; and obtaining a second value as an external force value acting on the robot, which is obtained by dividing the difference between the detected torque value and a reference torque value by the radius from the rotation axis of the predetermined joint to a monitoring point set on the surface of the robot, and converting the first value obtained by dividing the first value by the radius obtained by the radius obtained by the normal direction based on the angle between the tangential direction at the monitoring point of the circle having the radius and the normal direction with respect to the surface of the robot on which the monitoring point is set.

[0010] In the robot system control method according to the second aspect of this disclosure, as described above, a first value obtained by dividing the difference between the detected torque value and the reference torque value by the radius from the rotation axis of a predetermined joint to a monitoring point set on the robot surface is converted to a normal value based on the angle between the tangential direction at the monitoring point of the circle having the radius and the normal direction to the robot surface on which the monitoring point is set, and this second value is obtained as the external force value acting on the robot. As a result, an external force value that combines the tangential and radial forces at the monitoring point can be obtained, so that only the tangential force at the monitoring point is considered and the radial force at the monitoring point is not ignored. As a result, a robot system control method can be provided that can avoid obtaining an underestimated external force value. [Effects of the Invention]

[0011] According to this disclosure, it is possible to avoid obtaining an underestimated external force value, as described above. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows a robot system according to one embodiment. [Figure 2] This is a block diagram showing a robot according to one embodiment. [Figure 3]Figure (1) illustrates the acquisition of external force values ​​for a robot system according to one embodiment. [Figure 4] Figure (2) illustrates the acquisition of external force values ​​for a robot system according to one embodiment. [Figure 5] This is a flowchart illustrating the control process related to external force values ​​in a robot system according to one embodiment. [Modes for carrying out the invention]

[0013] The embodiments of this disclosure will be described below with reference to the drawings.

[0014] (Robot system configuration) Referring to Figures 1 to 4, the configuration of a robot system 100 according to one embodiment will be described. As shown in Figure 1, the robot system 100 is a system in which work is performed by a robot 10. The robot system 100 comprises a robot 10, a control unit 20, and a teaching unit 30.

[0015] Robot 10 is a robot that works in the same space as humans. For example, robot 10 is a collaborative robot or a service robot. Robot 10 is used without safety fences or the like. Also, robot 10 is a 6-axis vertical articulated robot. As shown in Figures 1 and 2, robot 10 includes a base 11, multiple links 12, multiple joints 13, multiple torque detection units 14, and a hand 15.

[0016] The base 11 is fixed to the installation surface, such as the floor, by fastening members such as bolts.

[0017] Multiple links 12 include links 12a, 12b, 12c, 12d, 12e, and 12f. Links 12a, 12b, 12c, 12d, 12e, and 12f are arranged in this order from the proximal end to the distal end. Multiple joints 13 include joints 13a, 13b, 13c, 13d, 13e, and 13f. Joints 13a, 13b, 13c, 13d, 13e, and 13f are arranged in this order from the proximal end to the distal end.

[0018] Joint 13a is located at the connection point between base 11 and link 12a. Joint 13a is configured to rotate link 12a relative to base 11 around a vertical rotation axis A1. Joint 13b is located at the connection point between link 12a and link 12b. Joint 13b is configured to rotate link 12b relative to link 12a around a rotation axis A2 perpendicular to rotation axis A1. Joint 13c is located at the connection point between link 12b and link 12c. Joint 13c is configured to rotate link 12c relative to link 12b around a rotation axis A3 parallel to rotation axis A2.

[0019] Joint 13d is located at the connection point between link 12c and link 12d. Joint 13d is configured to rotate link 12d relative to link 12c around a rotation axis A4 perpendicular to the rotation axis A3. Joint 13e is located at the connection point between link 12d and link 12e. Joint 13e is configured to rotate link 12e relative to link 12d around a rotation axis A5 perpendicular to the rotation axis A4. Joint 13f is located at the connection point between link 12e and link 12f. Joint 13f is configured to rotate link 12f relative to link 12e around a rotation axis A6 perpendicular to the rotation axis A5. As a result, joint 13f is configured to rotate the hand 15 attached to link 12f relative to the rotation axis A6.

[0020] Each of the joints 13a, 13b, 13c, 13d, 13e, and 13f is equipped with a motor 131, a reduction gear 132, and an encoder 133. The motor 131 is the drive source that drives the joint 13 and is configured as a servo motor. The reduction gear 132 is configured to reduce the rotational speed of the motor 131 and to transmit the driving force of the motor 131 to the link 12. The encoder 133 is configured to output information about the rotational position of the motor 131.

[0021] The torque detection unit 14 is a torque sensor. The torque detection unit 14 is located in all of the multiple joints 13. Specifically, the multiple torque detection units 14 include torque detection units 14a, 14b, 14c, 14d, 14e, and 14f, which are located in joints 13a, 13b, 13c, 13d, 13e, and 13f, respectively.

[0022] Torque detection unit 14a is configured to detect the torque value around the rotation axis A1 of joint 13a. Torque detection unit 14b is configured to detect the torque value around the rotation axis A2 of joint 13b. Torque detection unit 14c is configured to detect the torque value around the rotation axis A3 of joint 13c. Torque detection unit 14d is configured to detect the torque value around the rotation axis A4 of joint 13d. Torque detection unit 14e is configured to detect the torque value around the rotation axis A5 of joint 13e. Torque detection unit 14f is configured to detect the torque value around the rotation axis A6 of joint 13f.

[0023] The hand 15 is configured to perform operations on the workpiece to be worked on. For example, the hand 15 may be a gripping hand or a suction hand for the workpiece. The hand 15 may also be called a tool or end effector. The surface of the robot 10 includes the surface of the hand 15 and the surface of the workpiece held by the hand 15.

[0024] The control unit 20 is a robot controller. The control unit 20 is configured to control the operation of the robot 10. Specifically, the control unit 20 is configured to acquire instructions for the operation of the robot 10 from the user using the teaching unit 30, and to operate the robot 10 based on the acquired instructions. Furthermore, when the robot 10 performs a task, it may come into contact with objects in its vicinity, such as humans, other robots, or workpieces other than the workpiece being worked on, and external forces may act on the robot 10. Therefore, as will be described later, the control unit 20 is configured to perform control to acquire the values ​​of the external forces acting on the robot 10.

[0025] The teaching unit 30 is a teaching pendant. The teaching unit 30 is configured to receive operations to teach the robot 10 movements. The teaching unit 30 includes a display unit 31 that displays information such as teaching information, and an operation unit 32 that receives operations related to teaching.

[0026] (Acquisition of external force values) In this embodiment, as shown in Figure 3, the control unit 20 divides the difference between the detected torque value and the reference torque value by the radius R from the rotation axis of the joint 13 to the monitoring point 40 set on the surface of the robot 10, and obtains a value P. i This value, Pa, is converted to a normal value based on the angle θ between the tangential direction at the monitoring point 40 of a circle with radius R and the normal direction to the surface of the robot 10 on which the monitoring point 40 is set. i The control unit 20 is configured to acquire the Pa as an external force value acting on the robot 10. Specifically, the control unit 20 is configured to perform control. i =P i The formula / cosθ gives the value Pa i The system is configured to perform control to acquire the value. In this embodiment, the reference torque value is a theoretical torque value. The theoretical torque value is a theoretical torque value calculated based on the position and orientation of the robot 10 based on teaching, the value of the encoder 133, the link length of the robot 10, and the weight of the robot 10's components. Note that the value P i This is an example of the first value. Also, the value Pai is an example of the second value.

[0027] FIG. 3 shows an example of obtaining an external force value for the joint 13b. In this case, the control unit 20 obtains the detected torque value detected by the torque detection unit 14b, and performs control to obtain the reference torque value for the joint 13b calculated based on the position and orientation of the robot 10 based on the teaching and the value of the encoder 133. Then, the control unit 20 performs control to obtain the difference value between the obtained detected torque value and the reference torque value. Then, the control unit 20 divides the obtained difference value by the radius R from the rotation axis A2 of the joint 13b to the monitoring point 40 set on the surface of the link 12b rotated by the joint 13b, thereby obtaining the value P i . Then, the control unit 20 performs control to convert the value P i into the value Pa i . That is, the control unit 20 performs control to obtain the value Pa i = P i / cos θ. Since 0 < cos θ < 1, Pa i is larger than P i . Thus, the control unit 20 performs control to obtain the value Pa i as the external force value. Since the value P i representing the force in the tangential direction at the monitoring point 40 is converted based on the angle θ, the value Pa i as the external force value is obtained as the force obtained by synthesizing the force in the tangential direction and the force in the radial direction at the monitoring point 40. i

[0028] Although the example of obtaining the external force value for the joint 13b has been described, the same applies to the joints 13a, 13c, 13d, 13e, and 13f. Also, for the joint 13f, the monitoring point 40 is set on the surface of the hand 15 rotated by the joint 13b. For example, when the hand 15 has a suction pad, the monitoring point 40 is set on the surface of the suction pad.

[0029] Furthermore, in this embodiment, the monitoring point 40 is set at any position on the surface of the robot 10, not a fixed position. For example, the monitoring point 40 is set at any position specified by the user. Also, for example, the monitoring point 40 is set at an arbitrary position before the robot 10 is shipped. Also, for example, the monitoring point 40 is set based on a risk assessment that estimates the risks to the robot 10. For example, based on the risk assessment, the monitoring point 40 is set at the position on the surface of the robot 10 that has the smallest radius R among the positions that an object that applies an external force to the robot 10 can contact. Since a smaller radius R results in a larger external force value being obtained, setting the monitoring point 40 to have a small radius R makes it possible to avoid obtaining an underestimated external force.

[0030] Furthermore, in this embodiment, as shown in Figures 3 and 4, the monitoring points 40 are set at multiple positions on the surface of the robot 10. Specifically, the monitoring points 40 are set for each direction of movement of the robot 10. The control unit 20 uses the monitoring points 40 corresponding to the direction of movement of the robot 10 from among the multiple monitoring points 40 to perform control for acquiring external force values.

[0031] Figure 3 shows an example where the link 12b is rotated in the operating direction D1 by the joint 13b. Figure 4 shows an example where the link 12b is rotated in the operating direction D2 by the joint 13b. The operating directions D1 and D2 are the positive and negative directions of rotation around the rotation axis A2 of the joint 13b, respectively. The monitoring point 40 is set at two positions: a position on the surface 12ba of the advancing link 12b when the link 12b is rotated in the operating direction D1, and a position on the surface 12bb of the advancing link 12b when the link 12b is rotated in the operating direction D2. When the link 12b is rotated in the operating direction D1, the control unit 20 performs control to acquire the external force value using the monitoring point 40 set on the surface 12ba. Also, when the link 12b is rotated in the operating direction D2, the control unit 20 performs control to acquire the external force value using the monitoring point 40 set on the surface 12bb.

[0032] Although an example of the monitoring point 40 on the surface of link 12b has been described, the same applies to the monitoring points 40 on the surfaces of links 12a, 12c, 12d, 12e, and hand 15. That is, the monitoring points 40 on the surfaces of links 12a, 12c, 12d, 12e, and hand 15 are set in two positions to correspond to two rotation directions: positive and negative. A total of 12 monitoring points 40 are set.

[0033] Furthermore, in this embodiment, the control unit 20 sets the value Pa as the external force value. i If the threshold T1 is exceeded, the value Pa i The control unit 20 is configured to perform control that notifies a warning when the threshold T1 is exceeded, and to control the robot 10 to continue its operation. In addition, the control unit 20 is configured to control the value Pa as an external force value. i However, if the threshold T2, which is greater than the threshold T1, is exceeded, the value Pa i The system provides control to notify the system of an abnormality when the threshold T2 is exceeded, and controls the robot 10 to stop or to perform an evasive maneuver. Stopping the robot 10 means stopping the movement of each joint 13 of the robot 10. Performing an evasive maneuver means controlling the movement of the robot 10 to avoid an increase in the external force acting on the robot 10 by driving each joint 13 of the robot 10, for example, by moving the robot 10 in a direction that reduces the external force acting on the robot 10. The threshold T2 is defined, for example, by ISO / TS15066. Threshold T1 is an example of a first threshold. Threshold T2 is an example of a predetermined threshold and a second threshold.

[0034] The control unit 20 controls the value Pa iWhen a warning is issued that the threshold T1 has been exceeded, the system is configured to illuminate a light-emitting part such as an LED located on the robot 10, and to display a warning message on the display unit 31 of the teaching unit 30. Similarly, the control unit 20 is configured to detect the value Pa i When an abnormality is detected, such as the threshold T2 being exceeded, the system is configured to perform at least one of the following: illuminate an LED or other light-emitting part located on the robot 10, and display an abnormality notification message on the display unit 31 of the teaching unit 30.

[0035] (Control processing related to external force values) Referring to Figure 5, the control process related to the external force value of the robot system 100 according to this embodiment will be explained based on a flowchart. Each process in the flowchart is executed by the control unit 20.

[0036] In step S1, the difference between the detected torque value and the reference torque value is divided by the radius R from the rotation axis of the joint 13 to the monitoring point 40 set on the surface of the robot 10, resulting in a value P. i This value, Pa, is converted to a normal value based on the angle θ between the tangential direction at the monitoring point 40 of a circle with radius R and the normal direction to the surface of the robot 10 on which the monitoring point 40 is set. i However, this is obtained as an external force value acting on the robot 10. Specifically, Pa i =P i The formula / cosθ gives the value Pa i The following is obtained. In step S1, for each of the multiple joints 13, the value Pa i This is obtained.

[0037] Then, in step S2, the value Pa i It is determined whether the threshold T1 has been exceeded. In step S2, for each of the multiple joints 13, the value Pa i It is determined whether or not the threshold T1 has been exceeded. For all of the multiple joints 13, the value Pa iIf it is determined that the value does not exceed the threshold T1, the control process is terminated. Also, for at least one of the multiple joints 13, the value Pa i If it is determined that the threshold T1 has been exceeded, the process proceeds to step S3.

[0038] Then, in step S3, the value Pa i It is determined whether the threshold T2 has been exceeded. In step S3, for each of the multiple joints 13, the value Pa i It is determined whether or not the threshold T2 is exceeded. For all of the multiple joints 13, the value Pa i If it is determined that the threshold T2 is not exceeded, proceed to step S4.

[0039] Then, in step S4, the value Pa i A warning is issued when the threshold T1 is exceeded. For example, at least one of the following is done: an LED or other light-emitting part located on the robot 10 is illuminated, and a warning message is displayed on the display unit 31 of the teaching unit 30. The robot 10 continues to operate without being stopped or made to perform an evasive maneuver.

[0040] Furthermore, in step S3, for at least one of the multiple joints 13, the value Pa i If it is determined that the threshold T2 has been exceeded, proceed to step S5.

[0041] Then, in step S5, the value Pa i An abnormality is reported when the threshold T2 is exceeded. For example, at least one of the following is performed: a light-emitting part such as an LED placed on the robot 10 is made to light up, and a message reporting the abnormality is displayed on the display unit 31 of the teaching unit 30. In addition, the robot 10 is stopped, or the robot 10 is made to perform an evasive maneuver.

[0042] (Effects of this embodiment) In this embodiment, as described above, the difference between the detected torque value and the reference torque value is divided by the radius R from the rotation axis of the joint 13 to the monitoring point 40 set on the surface of the robot 10, resulting in a value P. i This value, Pa, is converted to a normal value based on the angle θ between the tangential direction at the monitoring point 40 of a circle with radius R and the normal direction to the surface of the robot 10 on which the monitoring point 40 is set. i A control unit 20 is provided to perform control to acquire the external force value acting on the robot 10. This makes it possible to acquire an external force value that is a combination of the tangential force and radial force at the monitoring point 40, so that only the tangential force at the monitoring point 40 is considered and the radial force at the monitoring point 40 is not ignored. As a result, it is possible to avoid acquiring an underestimated external force value.

[0043] Furthermore, in this embodiment, as described above, the control unit 20 is Pa i =P i The formula / cosθ gives the value Pa i This controls the acquisition of Pa. i =P i By using the formula / cosθ, the external force value obtained by combining the tangential and radial forces at the monitoring point 40 can be easily acquired.

[0044] Furthermore, in this embodiment, as described above, the monitoring point 40 is set at any position on the surface of the robot 10, not a fixed position. This allows the monitoring point 40 to be set at any position on the surface of the robot 10, making it easy to set the monitoring point 40 according to the robot 10.

[0045] Furthermore, in this embodiment, as described above, the monitoring point 40 is set at multiple locations on the surface of the robot 10. This allows the monitoring point 40 to be set at multiple locations on the surface of the robot 10, making it possible to acquire external force values ​​more appropriately compared to the case where the monitoring point 40 is set at only one location on the surface of the robot 10.

[0046] Furthermore, in this embodiment, as described above, the monitoring points 40 are set for each direction of movement of the robot 10, and the control unit 20 performs control to acquire external force values ​​using the monitoring points 40 corresponding to the direction of movement of the robot 10 from among the multiple monitoring points 40. As a result, even if the shape of the robot 10 differs for each direction of movement of the robot 10, the position where external forces are likely to act on the robot 10 differs for each direction of movement of the robot 10, but by acquiring external force values ​​using the monitoring points 40 corresponding to the direction of movement of the robot 10 from among the multiple monitoring points 40, external force values ​​can be acquired appropriately and effectively.

[0047] Furthermore, in this embodiment, as described above, the torque detection unit 14 is located in all of the multiple joints 13. This allows for the detection of both external forces that cannot be detected by simply placing the torque detection unit 14 in the proximal joint 13, and external forces that cannot be detected by simply placing the torque detection unit 14 in the tip joint 13. Therefore, when an external force acts on the robot 10, the external force acting on the robot 10 can be reliably detected. In addition, when the torque detection unit 14 is located in the tip joint 13, it can be used not only to acquire external force values ​​but also to control the movement of the hand 15. For example, when the robot 10 performs a task that requires precise control of force, such as fitting a screw as a workpiece or polishing a workpiece, the movement of the hand 15 can be accurately controlled based on the torque value detected by the torque detection unit 14 located in the tip joint 13.

[0048] Furthermore, in this embodiment, as described above, the control unit 20 determines the value Pa as the external force value. i If the threshold T2 is exceeded, the robot 10 is controlled to stop or to perform an evasive maneuver. This allows the robot 10 to stop or perform an evasive maneuver when a relatively large external force acts on it. As a result, it is possible to avoid placing a large load on the object that caused the external force and came into contact with the robot 10.

[0049] Furthermore, in this embodiment, as described above, the control unit 20 determines the value Pa as the external force value. i If the threshold T2 is exceeded, the value Pa i The system implements a control mechanism that notifies the operator when the threshold T2 is exceeded. This allows the operator to know that a relatively large external force has acted on the robot 10, and to take appropriate action regarding the relatively large external force acting on the robot 10.

[0050] Furthermore, in this embodiment, as described above, the control unit 20 determines the value Pa as the external force value. i If the threshold T1 is exceeded, the value Pa i The system provides a warning when the threshold T1 is exceeded, and controls the robot 10 to continue operating, with the external force value Pa being the external force value. i However, if the threshold T2, which is greater than the threshold T1, is exceeded, the value Pa i The system provides control to notify the operator of an abnormality when the threshold T2 is exceeded, and also controls the robot 10 to stop or to perform an evasive maneuver. In the case of a warning, this allows the operator to be notified that a situation that could lead to an abnormality has occurred. In addition, in the case of a warning, the operation of the robot 10 is continued, so a decrease in the operating rate of the robot 10 can be suppressed. In the case of an abnormality, the operator is notified that an abnormality has occurred, so the operator can take action against the abnormality. In addition, in the case of an abnormality, the robot 10 is stopped or the robot 10 is made to perform an evasive maneuver, so a large load can be avoided on the object that caused the external force and came into contact with the robot 10.

[0051] Furthermore, in this embodiment, as described above, the robot 10 is a robot that works in the same space as a human. When the robot 10 and a human work in the same space, external forces may act on the robot 10 due to contact between the robot 10 and the human. Therefore, when the robot 10 is a robot that works in the same space as a human, it is very effective to avoid obtaining an underestimated value of the external force.

[0052] The robot 10 includes a hand 15 for holding a workpiece, and the surface of the robot 10 includes the surface of the hand 15 and the surface of the workpiece held by the hand 15. This allows for the appropriate acquisition of external force values ​​when an external force acts on the surface of the hand 15 and the surface of the workpiece held by the hand 15.

[0053] (modified version) It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of this disclosure is defined by the claims rather than the description of the embodiments above, and includes all modifications (explanations) within the meaning and scope equivalent to the claims.

[0054] For example, the above embodiment shows an example where the robot is a 6-axis vertical articulated robot, but the disclosure is not limited thereto. In this disclosure, the robot may be a vertical articulated robot with axes other than 6, such as 7-axis or 8-axis robots. Furthermore, the robot may be a robot other than a vertical articulated robot. For example, the robot may be a horizontal articulated robot.

[0055] Furthermore, while the above embodiments show an example where the robot works in the same space as a human, this disclosure is not limited to this. In this disclosure, the robot may be a robot other than one that works in the same space as a human.

[0056] Furthermore, while the above embodiment shows an example in which a control unit acting as a robot controller performs control to acquire external force values, this disclosure is not limited to this. In this disclosure, a control unit other than the robot controller may perform control to acquire external force values.

[0057] Furthermore, while the above embodiment shows an example where the reference torque value is a theoretical torque value, this disclosure is not limited thereto. In this disclosure, the reference torque value may be a torque value other than the theoretical torque value. For example, the reference torque value may be a calculated torque value calculated based on the current value of the joint motor.

[0058] Furthermore, in the above embodiment, Pa i =P i An example of obtaining the external force value using the formula / cosθ has been shown, but this disclosure is not limited to this. In this disclosure, Pa i =P i You may also obtain the external force value using an equation other than / cosθ.

[0059] Furthermore, while the above embodiments show an example where the monitoring point is set at an arbitrary position on the surface of the robot, the disclosure is not limited thereto. In this disclosure, the monitoring point may be set at a fixed position on the surface of the robot.

[0060] Furthermore, while the above embodiments show an example where monitoring points are set at two locations on the surface of the robot for a single joint, the disclosure is not limited thereto. In this disclosure, monitoring points may be set at one or more locations on the surface of the robot for a single joint.

[0061] Furthermore, while the above embodiment shows an example in which monitoring points are set for each direction of robot movement, this disclosure is not limited to this. In this disclosure, monitoring points do not have to be set for each direction of robot movement. Also, there may be a mixture of joints in which monitoring points are set for each direction of robot movement and joints in which monitoring points are not set for each direction of robot movement.

[0062] Furthermore, while the above embodiment shows an example in which the torque detection unit is located in all of the multiple joints, the disclosure is not limited thereto. In this disclosure, the torque detection unit may be located in at least one of the multiple joints.

[0063] Furthermore, while the above embodiment shows an example of providing two thresholds—one for issuing a warning and allowing the robot to continue operating, and another for issuing an abnormality and stopping the robot or causing the robot to perform an evasive maneuver—this disclosure is not limited to this. In this disclosure, only one threshold may be provided for issuing an abnormality and stopping the robot or causing the robot to perform an evasive maneuver. Thresholds other than the threshold for issuing a warning and allowing the robot to continue operating, and the threshold for issuing an abnormality and stopping the robot or causing the robot to perform an evasive maneuver, may also be provided.

[0064] Furthermore, in the above embodiment, the external force values ​​for the two joints may be combined, and the combined external force value may be obtained. In this case, the first external force value for the first joint and the second external force value for the second joint may be obtained using the method of the above embodiment, and the combined external force value may be obtained by calculating the square root of the sum of the squares of the first and second external force values. The combined external force value may then be compared with a threshold value.

[0065] Furthermore, in the above embodiment, for example, joints 13b and 13c, where the rotation axes are parallel to each other, the external force values ​​of each joint may be compared, and the smaller of the two may be obtained as the external force value. Then, the obtained external force value may be compared with a threshold value.

[0066] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, then the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor.

[0067] [Pattern] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following embodiments.

[0068] (Aspect 1) A robot with multiple joints, A torque detection unit is positioned at a predetermined joint among the plurality of joints and detects a torque value around the rotation axis of the predetermined joint. A robot system comprising: a control unit that performs control to acquire as an external force value acting on the robot a second value obtained by dividing the difference between the detected torque value and the reference torque value by the radius from the rotation axis of the predetermined joint to a monitoring point set on the surface of the robot, and converting a first value obtained by dividing this second value by the normal direction based on the angle between the tangential direction of the circle having the radius at the monitoring point and the normal direction to the surface of the robot on which the monitoring point is set, as an external force value acting on the robot.

[0069] (Aspect 2) The control unit, Let the first value be Pi, the angle be θ, and the second value be Pai. Pai = Pi / cosθ The robot system according to embodiment 1, wherein control is performed to obtain the second value using the formula.

[0070] (Aspect 3) The robot system according to embodiment 1 or 2, wherein the monitoring point is set at any position on the surface of the robot, not at a fixed position.

[0071] (Aspect 4) The robot system according to any one of embodiments 1 to 3, wherein the monitoring points are set at multiple locations on the surface of the robot.

[0072] (Appendix 5) The monitoring points are set for each direction of the robot's movement, The robot system according to embodiment 4, wherein the control unit performs control to acquire the external force value using a monitoring point among the plurality of monitoring points that corresponds to the direction of movement of the robot.

[0073] (Aspect 6) The robot system according to any one of embodiments 1 to 5, wherein the torque detection unit is located in all of the plurality of joints.

[0074] (Aspect 7) The robot system according to any one of embodiments 1 to 6, wherein the control unit controls the robot to stop or to perform an avoidance maneuver when the second value as the external force value exceeds a predetermined threshold.

[0075] (Pattern 8) The robot system according to embodiment 7, wherein the control unit performs control to notify that the second value as the external force value has exceeded the predetermined threshold when the second value exceeds the predetermined threshold.

[0076] (Aspect 9) The control unit, If the second value, which is the external force value, exceeds the first threshold, control is performed to notify a warning that the second value has exceeded the first threshold, and control is performed to keep the robot running. A robot system according to any one of embodiments 1 to 8, wherein if the second value as the external force value exceeds a second threshold that is greater than the first threshold, the system performs control to notify of the abnormality that the second value has exceeded the second threshold, and controls the robot to stop or to perform an evasive maneuver.

[0077] (Aspect 10) The robot system according to any one of embodiments 1 to 9, wherein the robot is a robot that performs work in the same space as a human.

[0078] (Aspect 11) The robot includes a hand for holding a workpiece. The robot system according to any one of embodiments 1 to 10, wherein the surface of the robot includes the surface of the hand and the surface of the workpiece held by the hand.

[0079] (Aspect 12) A method for controlling a robot system comprising a robot with multiple joints, To detect the detected torque value around the rotation axis of a predetermined joint among the aforementioned plurality of joints, A method for controlling a robot system, comprising: dividing the difference between the detected torque value and the reference torque value by the radius from the rotation axis of the predetermined joint to a monitoring point set on the surface of the robot; converting the first value obtained by this first value into a value in the normal direction based on the angle between the tangential direction of the circle having the radius at the monitoring point and the normal direction to the surface of the robot on which the monitoring point is set; and obtaining this second value as an external force value acting on the robot. [Explanation of Symbols]

[0080] 10 Robots 13 joints 14 Torque detection unit 20 Control Unit 40 monitoring points 100 Robot Systems A1, A2, A3, A4, A5, A6 Rotation axis D1, D2 motion direction P i Value (first value) Pa i Value (second value) R radius T1 threshold (first threshold) T2 threshold (predetermined threshold, second threshold) θ angle

Claims

1. A robot with multiple joints, A torque detection unit is positioned at a predetermined joint among the plurality of joints and detects a torque value around the rotation axis of the predetermined joint. A robot system comprising: a control unit that performs control to acquire as an external force value acting on the robot a second value obtained by dividing the difference between the detected torque value and the reference torque value by the radius from the rotation axis of the predetermined joint to a monitoring point set on the surface of the robot, converting a first value obtained by dividing by the radius by the radius from the tangential direction of the circle having the radius at the monitoring point to the normal direction based on the angle between the tangential direction of the circle having the radius at the monitoring point and the normal direction of the robot surface on which the monitoring point is set, as an external force value acting on the robot.

2. The control unit, The first value mentioned above is P ｉ Let the angle be θ, and the second value be Pa ｉ year, Pa ｉ =P ｉ / cosθ The robot system according to claim 1, wherein control is performed to obtain the second value by the formula.

3. The robot system according to claim 1, wherein the monitoring point is set at any position on the surface of the robot, not at a fixed position.

4. The robot system according to claim 1, wherein the monitoring points are set at a plurality of positions on the surface of the robot.

5. The monitoring points are set for each direction of the robot's movement, The robot system according to claim 4, wherein the control unit performs control to acquire the external force value using a monitoring point among the plurality of monitoring points that corresponds to the direction of movement of the robot.

6. The robot system according to claim 1, wherein the torque detection unit is located in all of the plurality of joints.

7. The robot system according to claim 1, wherein the control unit controls the robot to stop or to perform an avoidance maneuver when the second value as the external force value exceeds a predetermined threshold.

8. The robot system according to claim 7, wherein the control unit performs control to notify that the second value as the external force value has exceeded the predetermined threshold when the second value exceeds the predetermined threshold.

9. The control unit, If the second value, which is the external force value, exceeds the first threshold, control is performed to issue a warning that the second value has exceeded the first threshold, and control is performed to keep the robot running. The robot system according to claim 1, wherein if the second value as the external force value exceeds a second threshold that is greater than the first threshold, the system performs control to notify of the abnormality that the second value has exceeded the second threshold, and controls the robot to stop or to perform an evasive maneuver.

10. The robot system according to claim 1, wherein the robot is a robot that performs work in the same space as a human.

11. The robot includes a hand for holding a workpiece. The robot system according to claim 1, wherein the surface of the robot includes the surface of the hand and the surface of the workpiece held by the hand.

12. A method for controlling a robot system comprising a robot with multiple joints, To detect the detected torque value around the rotation axis of a predetermined joint among the aforementioned plurality of joints, A method for controlling a robot system, comprising: dividing the difference between the detected torque value and the reference torque value by the radius from the rotation axis of the predetermined joint to a monitoring point set on the surface of the robot; converting a first value obtained by this first value into a normal value based on the angle between the tangential direction of the circle having the radius at the monitoring point and the normal direction to the surface of the robot on which the monitoring point is set; and obtaining a second value as an external force value acting on the robot.

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