Method for teaching the motion of a multi-joint robot arm, multi-joint robot arm, and program

Abstract

To provide a motion teaching method of a robot arm, a robot arm and a program which can shorten a tact time during which the robot arm is transferred into a proper attitude.SOLUTION: A motion teaching method of a robot arm is a motion teaching method of a multi-joint type robot arm having redundant joints, which includes a first step of teaching positions and attitudes of one or a plurality of joints, by moving the positions and the attitudes of the one or the plurality of joints arranged closer to a base end side than a tip part of the multi-joint type robot arm, while fixing at least positions and attitudes of at least the tip part of the multi-joint type robot arm.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an operation teaching method for an articulated robot arm, an articulated robot arm, and a program. [Background Art]

[0002] Conventionally, a robot arm operation teaching method called so-called direct teaching has been proposed, in which a user applies a force to the robot arm to freely move the robot arm and determine the position and posture of each joint of the robot arm (see, for example, Patent Document 1). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent No. 6773084 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] However, in the conventional technique, when trying various postures to determine an appropriate posture of the robot arm, the motion during the trial is also recorded as teaching data. Therefore, there is still room for improvement in reducing the tact time until the robot arm shifts to an appropriate posture when the robot arm operates.

[0005] The present invention has been made in view of such circumstances, and an object of the present invention is to provide an operation teaching method for an articulated robot arm, an articulated robot arm, and a program that can reduce the tact time until the robot arm shifts to an appropriate posture. [Means for Solving the Problem]

[0006] This application discloses a method for teaching the motion of a multi-joint robot arm having redundant joints, the method comprising a first step of teaching the position and orientation of one or more joints on the proximal end side of the multi-joint robot arm, while the position and orientation of at least the tip of the multi-joint robot arm is fixed.

[0007] Prior to the first step, a second step may be included in which, without fixing the position and orientation of at least the tip of the articulated robot arm, at least the tip of the articulated robot arm is moved to teach the position and orientation of the tip of the articulated robot arm.

[0008] Time-series data relating to the position and orientation of the tip from the start of the first step to the completion of the first step may be stored in the storage unit as teaching data.

[0009] Time-series data relating to the position and orientation of the tip from the start of the second step to the completion of the second step may be stored in the storage unit as teaching data.

[0010] Data relating to the position and orientation of the tip of the articulated robot arm from the completion of the second step to the completion of the first step may be excluded from the teaching data.

[0011] The teaching mode for the articulated robot arm includes a first mode in which the operation of the articulated robot arm is taught while the position and orientation of at least the tip of the articulated robot arm is fixed, and a second mode in which the operation of the articulated robot arm is taught while the position and orientation of at least the tip of the articulated robot arm is not fixed. When setting the first mode, the articulated robot arm may be moved to determine the position and orientation of one or more joints, and when setting the second mode, the articulated robot arm may be moved to determine the position and orientation of the tip.

[0012] Time-series data relating to the position and orientation of the tip from the time the device is set to the second mode until it switches to the first mode may be stored in the memory unit as teaching data.

[0013] This application discloses a multi-joint robot arm having redundant joints, wherein the operating mode of the multi-joint robot arm includes a mode in which, while the position and orientation of at least the tip of the multi-joint robot arm is fixed, the position and orientation of one or more joints on the proximal end side of the multi-joint robot arm is moved to teach the position and orientation of the one or more joints.

[0014] This application discloses a program that causes a multi-joint robot arm having redundant joints to perform a process of teaching the position and orientation of one or more joints on the proximal end side of the multi-joint robot arm, while the position and orientation of at least the tip of the multi-joint robot arm are fixed. [Effects of the Invention]

[0015] According to the present invention, the cycle time required to move the robot arm to an appropriate posture can be shortened. [Brief explanation of the drawing]

[0016] [Figure 1] This figure schematically shows the configuration of the robot arm according to this embodiment. [Figure 2] This is a block diagram showing the functional configuration of a robot controller. [Figure 3] This figure shows an example of the data content of the instruction data. [Figure 4] This graph shows an example of how the position information of the hand unit changes over time. [Figure 5] This graph shows an example of how the positional information of the first joint changes over time. [Figure 6]This is a flowchart showing teaching data registration processing. [Figure 7] This is a diagram for explaining the operation of a robot arm. MODE FOR CARRYING OUT THE INVENTION

[0017] Hereinafter, an embodiment of a robot arm will be described.

[0018] As shown in Figure 1, the robot arm 10 according to the present embodiment operates in accordance with pre-taught operations, such as a polishing operation on a workpiece, for example. The robot arm 10 is, for example, a 7-axis vertical articulated robot which is an example of an articulated robot arm having redundant joints, and includes, for example, a base 11, an arm portion 12, and a hand portion 13. The articulated robot arm having redundant joints includes, for example, a robot arm having at least 3 or more degrees of freedom with a horizontal articulated structure, or a robot arm having at least 7 or more degrees of freedom with a vertical articulated structure. Since the articulated robot arm having redundant joints has redundant joints, it is possible to move other links while keeping one link substantially stationary among the plurality of links constituting the robot arm. In other words, when the position and posture of one link are determined, the position and posture of other links may not be uniquely determined. The hand portion 13 is an example of a distal end portion.

[0019] The base 11 includes, for example, a first base 11A and a second base 11B. The first base 11A is installed on a floor surface and rotatably supports the second base 11B about an axis X1 extending in the vertical direction. The second base 11B is connected to the arm portion 12 and swingably supports the arm portion 12.

[0020] The arm portion 12 includes, for example, a first joint A1, a first arm 12A, a second joint A2, a second arm 12B, and a third joint A3.

[0021] The first joint A1 is located on the upper part of the second base 11B and is pivotably connected to the first arm 12A around an axis X2 extending in the longitudinal direction of the first arm 12A. The first joint A1 is pivotably connected to the first end of the first arm 12A around an axis X3 extending in the horizontal direction.

[0022] The first end of the first arm 12A is connected to the first joint A1, and the second end of the first arm 12A is connected to the second joint A2.

[0023] The second joint A2 pivotably connects the second end of the first arm 12A and the first end of the second arm 12B around an axis X4 extending perpendicular to the longitudinal direction of the first arm 12A. The second joint A2 pivotably connects the second arm 12B around an axis X5 extending in the longitudinal direction of the second arm 12B.

[0024] The first end of the second arm 12B is connected to the second joint A2, and the second end of the second arm 12B is connected to the third joint A3.

[0025] The third joint A3 pivotably connects the second end of the second arm 12B and the hand portion 13 around an axis X6 extending perpendicular to the longitudinal direction of the second arm 12B. The third joint A3 pivotably connects the hand portion 13 around an axis X7 extending in the longitudinal direction of the hand portion 13.

[0026] The hand portion 13, for example, has a main body and multiple fingers, and is a tool for gripping a workpiece.

[0027] Next, I will explain the robot controller 100.

[0028] As shown in Figure 2, the robot controller 100 controls the movement of the robot arm 10 and is implemented, for example, by a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Some or all of these components may be implemented by hardware (including circuitry) such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit), or by the cooperation of software and hardware. The program may be stored in a storage device such as the HDD or flash memory of the robot controller 100, or it may be stored on a removable storage medium such as a DVD or CD-ROM and installed on the HDD or flash memory of the robot controller 100 when the storage medium is inserted into a drive device.

[0029] The robot controller 100 includes, for example, a mode switching unit 110, an motion control unit 120, and a learning processing unit 130.

[0030] The mode switching unit 110 switches the operating mode of the robot arm 10 based on information input from the mode switching switch 20. As an example of input means other than the mode switching switch 20, the mode switching unit 110 may also switch the operating mode of the robot arm 10 based on information input from a teaching pendant or a control PC. The operating modes of the robot arm 10 include, for example, a hand fixed mode 150A, a hand free mode 150B, and an execution mode 150C. The hand fixed mode 150A and the hand free mode 150B are examples of operating modes used when teaching the operation of the robot arm 10. The hand fixed mode 150A is an operating mode in which the posture of the robot arm 10 is changed while the position and posture of the hand 13 are fixed when the user applies force to the robot arm 10. The hand free mode is an operating mode in which the position and posture of the hand 13 can be freely changed in the direction of the applied force when the user applies force to the robot arm 10. Execution mode 150C is an operating mode in which the robot arm 10 operates based on pre-programmed teaching data. Hand free mode 150B is an example of a second mode, and hand fixed mode 150A is an example of a first mode.

[0031] The motion control unit 120 controls the operation of the actuator group 30 based on information about the operating mode of the robot arm 10 input from the mode switching unit 110. The actuator group 30 includes, for example, an actuator that rotates the first arm 12A about axis X2, an actuator that swings the first arm 12A about axis X3, an actuator that rotates the second arm 12B about axis X5, an actuator that swings the second arm 12B about axis X4, an actuator that rotates the hand unit 13 about axis X7, and an actuator that swings the hand unit 13 about axis X6. For example, if the operating mode of the robot arm 10 input from the mode switching unit 110 is the hand unit fixed mode 150A, the motion control unit 120 sends a control signal to the actuator that drives the hand unit 13. As a result, even if the user applies force to the robot arm 10, the movement of the hand unit 13 in the direction of the applied force is restricted. On the other hand, if the operating mode of the robot arm 10 input from the mode switching unit 110 is, for example, the hand free mode 150B, the motion control unit 120 does not send a control signal to the actuator group 30, including the actuator that drives the hand unit 13. As a result, when a user applies force to the robot arm 10, movement of the hand unit 13 in the direction of the applied force is permitted.

[0032] The learning processing unit 130 determines, based on information about the operating mode of the robot arm 10 input from the mode switching unit 110, whether the operating mode of the robot arm 10 is an operating mode used when teaching the operation of the robot arm 10 (hand fixed mode 150A or hand free mode 150B). If the learning processing unit 130 determines that the operating mode of the robot arm 10 is an operating mode used when teaching the operation of the robot arm 10, it detects the force applied by the user to the robot arm 10 based on information input from the sensor group 40 and detects the teaching operation for the robot arm 10. The sensor group 40 includes, for example, sensors provided at each joint A1 to A3 that detect loads acting in the rotational direction around axes X2, X5, and X7, sensors that detect loads acting in the swinging direction around axes X3, X4, and X6, sensors that detect the rotational angle around axes X2, X5, and X7, and sensors that detect the swinging angle around axes X3, X4, and X6. The learning processing unit 130 registers the detected teaching actions as teaching data 160.

[0033] The learning processing unit 130 sequentially executes, for example, a hand-free mode 150B and a hand-fixed mode 150A as operating modes for the robot arm 10. In this case, the step of executing the hand-fixed mode 150A corresponds to the first step, and the step of executing the hand-free mode 150B corresponds to the second step. When executing the hand-fixed mode 150A, the learning processing unit 130 fixes the position and orientation of at least the hand portion 13 of the robot arm 10, and moves the position and orientation of the first joint A1 and the second joint A2 on the proximal end side of the hand portion 13 of the robot arm 10 to teach the position and orientation of the first joint A1 and the second joint A2. When executing the hand-free mode 150B, the learning processing unit 130 does not fix the position and orientation of at least the hand portion 13 of the robot arm 10, and moves at least the hand portion 13 of the robot arm 10 to teach the position and orientation of the hand portion 13 of the robot arm 10. In this case, the learning processing unit 130 determines the position and orientation of the hand unit 13 when the hand unit free mode 150B is set, and then, when the hand unit fixed mode 150A is set, it determines the position and orientation of the joints on the base end side of the robot arm 10 (first joint A1, second joint A2, third joint A3) that are closer to the hand unit 13, while maintaining the position and orientation of the hand unit 13. The learning processing unit 130 also registers, for example, historical information regarding the position and orientation of the hand unit 13 from when the robot arm 10's operation mode is set to hand unit free mode 150B until it switches to hand unit fixed mode 150A as teaching data 160 for the hand unit 13. On the other hand, the learning processing unit 130 excludes, for example, the historical information regarding the position and orientation of the hand unit 13 from the teaching data 160 for the hand unit 13 after the robot arm 10's operation mode is set to hand unit fixed mode 150A. Furthermore, the learning processing unit 130 registers, for example, historical information regarding the position and orientation of each joint A1, A2, and A3 from when the operation mode of the robot arm 10 is set to hand free mode 150B, then switched to hand fixed mode 150A, and then switched back to hand free mode 150B, as teaching data 160 for each joint A1, A2, and A3.

[0034] For example, if the operating mode of the robot arm 10 input from the mode switching unit 110 is execution mode 150C, the motion control unit 120 controls the operation of the actuator group 30 based on the teaching data 160 learned by the learning processing unit 130. As a result, the robot arm 10 operates according to the previously taught movements.

[0035] Figure 3 shows an example of the data content of the teaching data. In the example shown in the figure, at time T1, the operating mode of the robot arm 10 is set to hand unit free mode 150B, at time Ta, the operating mode of the robot arm 10 switches to hand unit fixed mode 150A, and the operating mode of the robot arm 10 is maintained in hand unit fixed mode 150A from time Ta to time Tn.

[0036] In this example, the position information of the third joint A3 at time T1 is "θ11", and the orientation information of the third joint A3 at time T1 is "φ11". The position information of the third joint A3 indicates, for example, the rotation angle of the hand unit 13 around axis X6, and corresponds to the position of the hand unit 13. The orientation information of the third joint A3 indicates the rotation angle of the hand unit 13 around axis X7, and corresponds to the orientation of the hand unit 13. Also, the position information of the third joint A3 at time Ta is "θ1a", and the orientation information of the third joint A3 at time Ta is "φ1a". The time-series data of the position information and orientation information of the third joint A3 at a predetermined time interval from time T1 to time Ta is then registered as teaching data 160 for the hand unit 13.

[0037] In this example, the position information of the first joint A1 at time T1 is "θ21", and the orientation information of the first joint A1 at time T1 is "φ21". The position information of the first joint A1 indicates the rotation angle of the first arm 12A around axis X3, and the orientation information of the first joint A1 indicates the rotation angle of the first arm 12A around axis X2. In addition, the position information of the first joint A1 at time Ta is "θ2a", and the orientation information of the first joint A1 at time Ta is "φ2a". In addition, the position information of the first joint A1 at time Tn is "θ2n", and the orientation information of the first joint A1 at time Tn is "φ2n". The time-series data of the position information and orientation information of the first joint A1 at a predetermined time interval from time T1 to time Tn is registered as teaching data 160 for the first joint A1. Although not shown in the diagram, time-series data of positional and orientation information of the second joint A2 and the third joint A3 during a predetermined time interval from time T1 to time Tn are also registered as teaching data 160 for the second joint A2 and the third joint A3.

[0038] Figure 4 is a graph showing an example of the time change in the position information of the hand unit 13. Figure 5 is a graph showing an example of the time change in the position information of the first joint A1. In the examples shown in Figures 4 and 5, at time T1, the operating mode of the robot arm 10 is set to hand unit free mode 150B. Then, at time Ta, when the position of the hand unit 13 reaches the desired position θA, the operating mode of the robot arm 10 switches to hand unit fixed mode 150A. After that, from time Ta to time Tn, the operating mode of the robot arm 10 is maintained in hand unit fixed mode 150A. In the example shown in Figure 4, the time series data regarding the position of the hand unit 13 from time T1 to time Ta is registered as teaching data 160 for the hand unit 13, and the time series data regarding the position of the hand unit 13 from time Ta to time Tn is excluded from the teaching data 160 for the hand unit 13. In the example shown in Figure 5, the time series data regarding the position of the first joint A1 from time T1 to time Tn is registered as teaching data 160 for the first joint A1.

[0039] Next, the process of registering teaching data 160, which is performed by the robot controller 100 according to this embodiment, will be described.

[0040] As shown in Figure 6, the robot controller 100 first switches the operating mode of the robot arm 10 to hand unit free mode 150B based on the information input from the mode switching switch 20 (step S10).

[0041] Next, the robot controller 100 detects the teaching motion of the robot arm 10 based on the information input from the sensor group 40 (step S11).

[0042] Next, the robot controller 100 determines whether the position of the hand unit 13 has reached the desired position based on the teaching operation detected in step S11 (step S12).

[0043] If the robot controller 100 determines that the position of the hand unit 13 has not reached the desired position (step S12 = NO), it returns to step S11 and continues detecting the teaching motion until the position of the hand unit 13 reaches the desired position.

[0044] On the other hand, if the robot controller 100 determines that the hand unit 13 has reached a desired position (step S12 = YES), it registers teaching data 160 related to the hand unit 13 based on the teaching operation history data detected in step S11 (step S13).

[0045] Next, the robot controller 100 determines whether the posture of the arm 12 is the desired posture based on the teaching operation detected in step S11 (step S14).

[0046] If the robot controller 100 determines that the posture of the arm 12 is the desired posture (step S14 = YES), it terminates the flowchart shown in Figure 6. On the other hand, if the robot controller 100 determines that the posture of the arm 12 is not the desired posture (step S14 = NO), it switches the operation mode of the robot arm 10 to hand fixed mode 150A based on the information input from the mode switching switch 20 (step S15).

[0047] Next, the robot controller 100 detects the teaching motion of the robot arm 10 based on the information input from the sensor group 40 (step S16).

[0048] Next, the robot controller 100 determines whether the posture of the arm 12 has reached the desired posture based on the teaching operation detected in step S16 (step S17).

[0049] If the robot controller 100 determines that the posture of the arm 12 has not reached the desired posture (step S17=NO), it returns to step S16 and continues detecting the teaching motion until the posture of the arm 12 reaches the desired posture.

[0050] On the other hand, if the robot controller 100 determines that the posture of the arm 12 has reached a desired posture (step S17 = YES), it switches the operation mode of the robot arm 10 to hand free mode 150B based on the information input from the mode switching switch 20 (step S18).

[0051] Then, the robot controller 100 registers teaching data 160 related to the arm unit 12 based on the teaching operation history data detected in step S16 (step S19), and the flowchart shown in Figure 6 is completed.

[0052] Next, the operation of the method for teaching the movement of the robot arm 10 according to this embodiment will be described. As shown in Figure 7, when transporting a workpiece W held by the hand portion 13 of the robot arm 10 to the processing unit 200 while avoiding an obstacle MA, first, the operating mode of the robot arm 10 is set to hand portion free mode 150B, and the hand portion 13 of the robot arm 10 is moved above the obstacle MA in a state where the posture of the hand portion 13 can be freely changed. In this case, the history data of the changes in the posture of the robot arm 10 is registered as teaching data 160.

[0053] Next, the robot arm 10 is set to the hand unit fixed mode 150A, and with the position and orientation of the hand unit 13 fixed, the hand unit 13 is moved to the processing unit 200. In this case, the history data of the changes in the orientation of the robot arm 10 is registered as teaching data 160.

[0054] Here, when the hand unit 13 is moved from above the obstacle MA to the processing unit 200, the position and orientation of the hand unit 13 are fixed, eliminating the need to readjust the orientation of the hand unit 13 in response to changes in the orientation of the robot arm 10. In other words, the orientation of the robot arm 10 can be adjusted smoothly. As a result, the efficient operation of the robot arm 10 is registered as teaching data 160, and the cycle time until the robot arm 10 is moved to an appropriate orientation can be shortened.

[0055] Furthermore, the posture of the hand unit 13 at the time the robot arm 10's operating mode is switched from hand unit free mode 150B to hand unit fixed mode 150A is registered as teaching data 160. After switching to hand unit fixed mode 150A, the posture of the hand unit 13 is maintained, so data regarding the position and posture of the robot arm 10's hand unit 13 is not registered as teaching data 160. This contributes to reducing the amount of teaching data 160.

[0056] Furthermore, the above embodiment can also be implemented in the following form.

[0057] In the above embodiment, data relating to the position and orientation of the robot arm 10 was registered as teaching data 160. However, parameters relating to constraint conditions when solving the optimal solution for the operation of the robot arm 10 based on the inverse equation of motion may also be registered as teaching data 160.

[0058] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The present invention can be modified or improved without departing from its spirit, and equivalents thereof are also included. That is, any design modifications made to each embodiment by those skilled in the art are also included within the scope of the present invention, as long as they retain the features of the present invention. For example, the elements and their arrangement, materials, conditions, shapes, sizes, etc., of each embodiment are not limited to those exemplified and can be modified as appropriate. Furthermore, each embodiment is illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible, and these are also included within the scope of the present invention as long as they retain the features of the present invention. [Explanation of Symbols]

[0059] 10...Robot arm, 11...Base, 11A...First base, 11B...Second base, 12...Arm section, 12A...First arm, 12B...Second arm, 13...Hand section, 20...Mode switching switch, 30...Actuator group, 40...Sensor group, 100...Robot controller, 110...Mode switching unit, 120...Motion control unit, 130...Learning processing unit, 150A...Hand section fixed mode, 150B...Hand section free mode, 150C...Execution mode, 160...Teaching data, A1...First joint, A2...Second joint, A3...Third joint.

Claims

1. A method for teaching the motion of a multi-joint robot arm whose posture can be changed while the position and posture of the tip are fixed, The first step includes controlling the tip of the articulated robot arm so that the position and orientation of at least the tip of the articulated robot arm is fixed with respect to the joint connected to the tip, and then moving the position and orientation of one or more joints on the proximal end side of the articulated robot arm to teach the position and orientation of the one or more joints, A method for teaching the movements of a robotic arm.

2. Prior to the first step, the process includes a second step of teaching the position and orientation of the tip of the articulated robot arm by moving at least the tip of the articulated robot arm without fixing the position and orientation of at least the tip of the articulated robot arm. A method for teaching the operation of a robot arm according to claim 1.

3. Time-series data relating to the position and posture of one or more joints from the start of the second step to the completion of the first step is stored in the storage unit as teaching data. The method for teaching the operation of a robot arm according to claim 2.

4. Time-series data relating to the position and orientation of the tip from the start of the second step to the completion of the second step is stored in the storage unit as teaching data. A method for teaching the operation of a robot arm according to claim 2 or 3.

5. The data relating to the position and orientation of the tip of the articulated robot arm from the completion of the second step until the completion of the first step is excluded from the teaching data. The method for teaching the operation of a robot arm according to claim 4.

6. The teaching modes of the aforementioned articulated robot arm are: A first mode in which the operation of the articulated robot arm is taught while the position and orientation of at least the tip of the articulated robot arm are fixed, A second mode for teaching the movement of the articulated robot arm while not fixing the position and orientation of at least the tip of the articulated robot arm, Includes, When setting the first mode, the articulated robot arm is moved to determine the position and orientation of one or more joints. When setting the second mode, the articulated robot arm is moved to determine the position and orientation of the tip. A method for teaching the operation of a robot arm according to any one of claims 1 to 5.

7. Time-series data relating to the position and orientation of the tip from the time the device is set to the second mode until it switches to the first mode is stored in the memory unit as teaching data. The method for teaching the operation of a robot arm according to claim 6.

8. A multi-joint robot arm whose posture can be changed while the position and posture of the tip are fixed, The operation mode of the articulated robot arm includes a mode in which, while controlling the tip of the articulated robot arm so that the position and orientation of at least the tip of the articulated robot arm is fixed with respect to the joint connected to the tip, the position and orientation of one or more joints on the proximal end side of the articulated robot arm is moved to teach the position and orientation of the one or more joints. Robot arm.

9. A multi-joint robot arm whose posture can be changed while the position and posture of the tip are fixed, With the tip of the articulated robot arm controlled so that the position and orientation of at least the tip of the articulated robot arm are fixed with respect to the joint connected to the tip, the position and orientation of one or more joints on the base end side of the articulated robot arm are moved, and a process is performed to teach the position and orientation of the one or more joints. program.

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