JP2017200710A - Abnormality diagnostic method and abnormality diagnostic device of joint driving robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality diagnostic method of a joint driving robot capable of reliably detecting an abnormality of a robot.SOLUTION: An operation program storage part 112 of a control device 100 stores an operation program. A diagnostic object process setting part 114 of the control device 100 sets a process whose required accuracy is higher than a predetermined threshold Th as a diagnostic object process. A robot control part 116 of the control device 100 controls a robot 10 according to the operation program. An abnormality diagnostic part 124 of the control device 100 performs abnormality diagnosis using a measurement value and a reference value on the diagnostic object process when the robot 10 is controlled in the diagnostic object process.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an abnormality diagnosis method and an abnormality diagnosis device for a joint drive robot, and more particularly to an abnormality diagnosis method and an abnormality diagnosis device for a joint drive robot for diagnosing an abnormality of a joint drive robot.

  By using a robot (robot arm) such as an industrial robot, a predetermined operation such as welding is performed at a manufacturing site of a vehicle body or the like. The robot moves to a desired position by executing an operation program (teaching data) programmed by robot teaching (teaching), for example.

  The robot is controlled such that an end effector provided at the tip of the robot moves to a desired position by driving each joint by a drive source such as a motor. The power of the motor is transmitted to each joint of the robot via a speed reducer. In such a robot, there is a possibility that an abnormality occurs in the robot due to deterioration of a motor or a speed reducer and the robot does not operate. Therefore, it is desirable to diagnose a robot abnormality before the robot stops operating.

  In relation to the above technique, Patent Document 1 discloses a robot deterioration diagnosis apparatus. The robot degradation diagnosis apparatus according to Patent Document 1 is a characteristic data group (cycle time, deceleration included in each joint axis) as data used for degradation diagnosis every time one cycle regeneration operation in a work program used for degradation diagnosis is completed. Machine life, average motor torque, maximum torque, average rotation speed, maximum rotation speed, etc.) are recorded in memory. The robot deterioration diagnosis apparatus according to Patent Document 1 analyzes this characteristic data group by a statistical method, and diagnoses a mechanical deterioration symptom of the robot arm based on the analysis result. With such a configuration, the robot deterioration diagnosis apparatus according to Patent Document 1 can check whether or not the robot drive system has deteriorated even when there is a difference in characteristic data between the previous reproduction operation and the current reproduction operation. Judgment can be made.

JP 2005-148873 A

  In the method according to Patent Document 1, a deterioration symptom is diagnosed using characteristic data generated when a one-cycle regeneration operation in a work program is completed. That is, in the method according to Patent Document 1, characteristic data for one cycle in the work program is used. Here, when the characteristic data for one cycle in the work program is simply used, the robot abnormality can be detected and detected if one cycle in the work program does not include a process that makes the robot abnormality manifest. There is a fear. In other words, if a process that makes a robot abnormality manifest is not included, characteristic data such as cycle time may not show an abnormality (deterioration) even if the robot has an abnormality.

  The present invention provides an abnormality diagnosis method and an abnormality diagnosis apparatus for a joint-driven robot capable of more reliably detecting an abnormality of a robot.

  An abnormality diagnosis method for a joint drive robot according to the present invention is an abnormality diagnosis method for diagnosing an abnormality of a joint drive robot that operates by driving a joint, and the robot has a predetermined target position and required accuracy, respectively. The process is controlled by an operation program composed of a plurality of associated processes, and the process having the required accuracy higher than a predetermined value among the plurality of processes is set as a diagnosis target process, and the operation program And controlling so that the difference between the position of the control target of the robot and the target position is within an allowable range related to the required accuracy in the diagnosis target step, and the measured value and the measurement for the diagnosis target step An abnormality diagnosis of the robot is performed using a reference value related to the value.

  An abnormality diagnosis apparatus for a joint drive robot according to the present invention is an abnormality diagnosis apparatus for diagnosing an abnormality of a joint drive robot that operates by driving a joint, and the robot has a predetermined target position and required accuracy, respectively. A setting means that is controlled by an operation program composed of a plurality of associated steps, and that sets the step whose accuracy is higher than a predetermined value from the plurality of steps as a diagnosis target step; Using the operation program, when the control is performed so that the difference between the position of the control target of the robot and the target position is within an allowable range related to the required accuracy in the diagnosis target step, the diagnosis target step And a diagnostic means for diagnosing the abnormality of the robot using the measured value for and the reference value related to the measured value.

  In a process with high required accuracy, it is difficult to control the robot so that the difference between the position to be controlled by the robot and the target position is within an allowable range. And the tendency is so remarkable that the robot in which abnormality has generate | occur | produced. That is, by performing control in a process with high required accuracy, it is possible to reveal the abnormality of the robot. In other words, the measured values in the process with high required accuracy tend to be different between when an abnormality occurs in the robot and when no abnormality occurs. Therefore, according to the present invention, it is possible to detect the abnormality of the robot more reliably by performing the abnormality diagnosis using the measurement value and the reference value in the process with high required accuracy.

Preferably, the working time required for at least one process including the diagnosis target process is measured, and an abnormality diagnosis of the robot is performed using a difference between the measured working time and a reference value of the working time. .
The working time can become longer as the degree of abnormality of the robot increases. Therefore, it is possible to detect the abnormality of the robot more reliably by performing the abnormality diagnosis using the working time.

Preferably, a time from the end of the process before the diagnosis target process to the end of the diagnosis target process is measured as the work time.
By being configured in this way, it is possible to eliminate the influence of other devices or the like on the measured working time. Therefore, it becomes possible to detect the abnormality of the robot more reliably.

  ADVANTAGE OF THE INVENTION According to this invention, the abnormality diagnosis method and abnormality diagnosis apparatus of a joint drive robot which can detect abnormality of a robot more reliably can be provided.

1 is a diagram illustrating a robot control system according to a first embodiment. FIG. 2 is a functional block diagram illustrating a configuration of a control device according to the first embodiment. It is a figure which illustrates the operation | movement program stored by the operation | movement program storage part concerning Embodiment 1. FIG. It is a figure which shows the content managed by the measured value management part concerning Embodiment 1. FIG. It is a figure which shows the state which operation | movement of a robot changes to the diagnostic object process from the process before a diagnostic object process. It is a figure for demonstrating the control action of a robot. It is a figure for demonstrating the difference of the cycle time between the time of normal and abnormal of a robot. 3 is a flowchart illustrating an abnormality diagnosis method performed by the control device according to the first embodiment; It is a flowchart which shows the robot control process in the flowchart shown in FIG. It is a flowchart which shows the abnormality diagnosis process in the flowchart shown in FIG.

(Embodiment 1)
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a robot control system 1 according to the first embodiment. The robot control system 1 includes a robot 10 and a control device 100. The control apparatus 100 controls the robot 10 to a desired position by controlling the operation of the robot 10 using the operation program. Further, the control device 100 has a function as an abnormality diagnosis device that diagnoses an abnormality of the robot 10. Details will be described later.

  The robot 10 is installed in the vicinity of a vehicle production line. The robot 10 is a robot for performing predetermined work such as welding (for example, spot welding) on the vehicle, for example. For example, when the vehicle is manufactured, the robot 10 performs welding or the like using a welding gun or the like provided on the end effector 12. The robot 10 includes one or more joints 14, a motor (not shown) that drives the joints 14, and a speed reducer (not shown) that transmits the power of the motors to the joints 14. The robot 10 performs a desired operation when the motor is controlled by the control device 100. That is, the robot 10 is a joint driving robot that operates by driving the joint 14. And the control apparatus 100 controls the robot 10 so that the position of the front-end | tip part 12a of the end effector 12 may become a desired position (target position) in each process in an operation | movement program. That is, in the present embodiment, the control target of the robot 10 is the tip portion 12a.

  The control device 100 has a function as a computer, for example. The control device 100 may be mounted inside the robot 10 or may be connected to the robot 10 so as to be communicable via wire or wireless. The control device 100 includes a central processing unit (CPU) 101, a read only memory (ROM) 102, a random access memory (RAM) 103, an input / output (I / O) 104, and a user interface (UI) 105.

  The CPU 101 has a function as a processing device that performs control processing, arithmetic processing, and the like. The ROM 102 has a function for storing a control program and a calculation program executed by the CPU 101. The RAM 103 has a function for temporarily storing processing data and the like. The I / O 104 is an input / output device that inputs data and signals from the outside and outputs data and signals to the outside. The UI 105 includes an input device such as a keyboard and an output device such as a display. The UI 105 may be configured as a touch panel in which an input device and an output device are integrated. Here, the ROM 102 is configured to store an operation program (teaching data) for controlling the robot 10.

  Here, in the present embodiment, the actual position of the control target of the robot 10 is not controlled to exactly match the target position by the control of the control device 100. There may be a certain degree of deviation between the actual position of the control target of the robot 10 and the target position, depending on the required accuracy predetermined in each step of the operation program. That is, when the actual position converges (arrives) within the allowable range corresponding to the required accuracy with the target position as a reference, the control device 100 can control the position of the control target of the robot 10 to the target position in that process. Then, the control in the process is finished and the control in the next process is performed. That is, in each process, the control device 100 controls the robot 10 so that the difference (deviation) between the position of the control target (tip portion 12a) of the robot 10 and the target position is within an allowable range corresponding to the required accuracy. To do.

  If the required accuracy is high, the corresponding allowable range is small, and if the required accuracy is low, the corresponding allowable range is large. By performing such control, the actual position can be quickly converged within the allowable range in a process with low required accuracy, so that the work time can be shortened.

  FIG. 2 is a functional block diagram of the configuration of the control device 100 according to the first embodiment. The control device 100 includes an operation program storage unit 112, a diagnosis target process setting unit 114, a robot control unit 116, an actual position acquisition unit 118, a work time measurement unit 120, a measured value management unit 122, an abnormality diagnosis unit 124, and a warning output unit. 126. Each component of the control device 100 illustrated in FIG. 2 can be realized by the CPU 101 executing a program stored in the ROM 102. Further, a necessary program may be recorded in an arbitrary nonvolatile recording medium, and the program may be installed as necessary. 2 are not limited to being realized by software as described above, and may be realized by hardware such as some circuit elements.

  Further, one or more of the components shown in FIG. 2 may be realized by a device different from the control device 100. For example, the diagnosis target process setting unit 114, the working time measurement unit 120, the measurement value management unit 122, the abnormality diagnosis unit 124, and the warning output unit 126 may be realized by an abnormality diagnosis device different from the control device 100. That is, the device that controls the robot 10 and the device that diagnoses the abnormality of the robot 10 may be physically different devices. In this case, the abnormality diagnosis apparatus can have the same configuration as the hardware configuration of the control apparatus 100 shown in FIG.

The operation program storage unit 112 stores an operation program for operating the robot 10.
FIG. 3 is a diagram illustrating an operation program 200 stored by the operation program storage unit 112 according to the first embodiment. The operation program 200 includes a plurality of processes “1” to “M” (M is an integer of 2 or more). Each process is associated with an operation speed of the robot in the process, a required accuracy in the process, a target position in the process, presence / absence of diagnosis target setting (diagnosis target setting), and an I / O signal.

  The movement speed of the robot increases as the number increases. In the example of FIG. 3, the fastest speed “9” is set in all the steps. The required accuracy indicates how close the control target position of the robot 10 should be to the target position. As the required accuracy is higher, in the process, it is necessary to perform control so that the position of the control target of the robot 10 approaches the target position. Here, the required accuracy is higher as the number is smaller. In the example of FIG. 3, the required accuracy is provided from the highest accuracy “0” to the lowest accuracy “4”. For example, in step “1”, control is performed with accuracy “1”, and in step “2”, control is performed with accuracy “2”. Further, in the process “N” (N is an integer of 1 to M), the control is performed with the highest accuracy “0”. Further, in the process “N-1” immediately before the process “N”, the control is performed with the accuracy “2”.

  Target positions Pt (Pt_1 to Pt_3,..., Pt_N-1 to Pt_N,... Pt_M) indicate desired positions of the distal end portion 12a of the end effector 12 in the corresponding steps. Here, the target position may indicate position coordinates (x, y, z) of the tip 12a to be controlled in the three-dimensional space. Furthermore, the target position may indicate a joint angle (target joint angle) of each joint 14 such that the distal end portion 12a reaches the target position. The control device 100 can control the distal end portion 12a of the robot 10 to the target position by controlling each joint 14 to the target joint angle.

  The diagnosis target setting indicates whether or not the process is a target for abnormality diagnosis of the robot 10. The process in which the diagnosis target setting is set to “present” is a process to be diagnosed, that is, a diagnosis target process. The abnormality diagnosis unit 124 performs abnormality diagnosis of the robot 10 using the measured values measured for the process (diagnosis target process) in which the diagnosis target setting is set to “present”. Details will be described later.

  The “I / O signal” indicates a signal transmitted and received when the control device 100 (or the robot 10) communicates with other devices (devices other than the control device 100 and the robot 10) in each process. When any signal is set in the “I / O signal”, in the process, the robot 10 cooperates with another device (or worker) or cooperates with another device (or worker). Work. On the other hand, in a process in which nothing is set in the “I / O signal”, communication with other devices is not performed. In other words, in the process, the robot 10 to be diagnosed operates alone.

  The “interlock signal” set in the process “2” is a signal for stopping the operation of the robot 10 until, for example, another device (or operator) performs some operation and terminates the operation. . “Welder communication” set in the process “3” indicates a signal that is input / output for causing the welding machine attached to the end effector 12 to perform welding. The “completion signal” set in the process “M” is a signal for notifying other devices that all the processes of the operation program 200 have been completed.

  The diagnosis target process setting unit 114 (setting unit) sets at least one of the plurality of processes of the operation program 200 as a diagnosis target process. Here, the diagnosis target process setting unit 114 sets a process whose required accuracy is higher than a predetermined value as a diagnosis target process. Here, the “predetermined value” is, for example, accuracy “1”. Therefore, a process having a required accuracy higher than a predetermined value is a process having an accuracy of “0”. In the example of FIG. 3, the required accuracy of the process “N” is the highest accuracy “0”. Therefore, the diagnosis target process setting unit 114 sets the process “N” as a diagnosis target process.

  The robot control unit 116 controls the robot 10 according to the operation program 200. Specifically, the robot control unit 116 transmits a control signal to the robot 10 so as to control the position of the tip 12a to the target position in each process. For example, the control signal may be a target joint angle of each joint 14. The motor that drives each joint 14 adjusts the joint angle of each joint 14 according to the control signal. Details will be described later. Further, the robot control unit 116 may perform feedback control using the actual position of the distal end portion 12a of the robot 10 acquired by an actual position acquisition unit 118 described later.

  Here, “the robot control unit 116 controls the position of the tip 12a to the target position”, but as described above, the robot control unit 116 strictly matches the position of the tip 12a with the target position. It does not mean to control. The robot control unit 116 controls the robot 10 so that the actual position of the tip 12a reaches an allowable range corresponding to the required accuracy in each process. That is, the robot control unit 116 performs control so that the difference between the position of the tip 12a of the robot 10 and the target position is within an allowable range regarding the required accuracy in each step. Therefore, the robot controller 116 controls the robot 10 so that the actual position of the tip 12a approaches the target position as the required accuracy is higher.

  The actual position acquisition unit 118 acquires the actual position of the distal end portion 12 a in accordance with a signal from the robot 10. For example, when a sensor for measuring the position of the distal end portion 12a is provided, the actual position acquisition unit 118 may receive a signal from the sensor. If each joint 14 is provided with an encoder that measures the actual joint angle of the joint 14, the actual position acquisition unit 118 receives a signal from the encoder, and the position of the distal end portion 12a from the received signal. May be calculated. Further, the actual position acquisition unit 118 may output information indicating the acquired actual position to the robot control unit 116 for feedback control before each process of the robot 10 is completed. On the other hand, the actual position acquisition unit 118 outputs, to the measurement value management unit 122, information indicating the position (arrival position) reached by the distal end portion 12a when each process of the robot 10 is completed.

  The work time measuring unit 120 (measurement means) measures the work time (cycle time) for the diagnosis target process and the set process. Specifically, the work time measuring unit 120 measures the cycle time including the diagnosis target process. More specifically, the work time measuring unit 120 measures the time from the end of the process immediately before the diagnosis target process to the end of the diagnosis target process as a cycle time (process cycle time). Details will be described later. The work time measurement unit 120 outputs information indicating the measured process cycle time to the measurement value management unit 122.

  The measurement value management unit 122 manages the measurement values measured along with the operation of the robot 10 in the diagnosis target process. Specifically, the measurement value management unit 122 manages the process cycle time and the value related to the position of the tip 12a. This will be described below with reference to the drawings.

  FIG. 4 is a diagram illustrating the contents managed by the measurement value management unit 122 according to the first embodiment. The measurement value management unit 122 manages the process cycle time, the arrival position, the target position, and the arrival deviation amount, which are measurement values, for the process “N” that is the diagnosis target process. Furthermore, the measurement value management unit 122 manages the process cycle time, the arrival position, the target position, and the arrival deviation amount, which are reference values for abnormality diagnosis, for the process “N” that is the diagnosis target process. Here, the “reference value” is a value when the robot 10 is normal (ideally, there is no deterioration). In addition, the “arrival deviation amount” indicates the deviation amount between the arrival position and the target position when the control in the process is completed.

  As shown in FIG. 4, Ts indicates a reference value of the process cycle time in the process “N”, and T indicates a measured value of the process cycle time. Further, Pt_N indicates the target position of the distal end portion 12a of the robot 10 in the process “N”, and P indicates the arrival position of the distal end portion 12a of the robot 10. At this time, in an ideal state where the robot 10 is completely normal, the tip 12a of the robot 10 can reach the target position. Accordingly, the arrival deviation amount at this time is zero. On the other hand, as the robot 10 is used, it becomes difficult to control the tip portion 12a of the robot 10 so as to completely match the target position due to deterioration of the speed reducer of the robot 10 or the like. Therefore, at the time of measurement, a non-zero arrival deviation amount ΔP exists between the target position Pt_N and the arrival position P. The arrival deviation amount ΔP is within an allowable range regarding the required accuracy in the process “N”.

  The abnormality diagnosis unit 124 (diagnostic means) performs abnormality diagnosis of the robot 10 using the measured value and the reference value for the diagnosis target process. Specifically, the abnormality diagnosis unit 124 performs abnormality diagnosis of the robot 10 according to the cycle time for the diagnosis target process. Details will be described later. If the abnormality diagnosis unit 124 determines that an abnormality has occurred in the robot 10, the abnormality diagnosis unit 124 outputs a command to output a warning to the warning output unit 126.

  The warning output unit 126 outputs a warning indicating that an abnormality has occurred in the robot 10 in response to the abnormality diagnosis by the abnormality diagnosis unit 124. The warning output unit 126 may output different warnings depending on the degree of abnormality of the robot 10. The warning may be a visual detection such as a lamp, or may be a visual detection such as an alarm sound.

Next, an abnormality diagnosis mechanism according to the first embodiment will be described.
FIG. 5 is a diagram illustrating a state in which the operation of the robot 10 transitions from the process before the diagnosis target process to the diagnosis target process. FIG. 5 illustrates a state in which the process transitions from the process “N-1” to the process “N” that is a diagnosis target process. In the process “N−1”, the robot 10 is controlled to a position (posture) as illustrated in FIG. (A), and in the process “N”, the robot 10 is positioned as illustrated in (B) ( Attitude). At this time, when the process transitions from the process “N-1” to the process “N”, the position of the tip 12a of the robot 10 moves from the arrival position P_N-1 to the arrival position P_N as indicated by an arrow A. Here, the reaching position P_N-1 is within an allowable range in the process “N-1” with the target position Pt_N−1 as a reference. That is, the difference between the reaching position P_N-1 and the target position Pt_N-1 is within an allowable range in the process “N-1”. Similarly, the reaching position P_N is within an allowable range in the process “N” with the target position Pt_N as a reference. That is, the difference between the reaching position P_N and the target position Pt_N is within an allowable range in the process “N”.

  Here, the difference (arrival deviation amount ΔP) between the arrival position P_N and the target position Pt_N may be, for example, the distance between the arrival position P_N and the target position Pt_N. In this case, the “allowable range” may be the maximum allowable value of the distance between the reaching position P_N and the target position Pt_N. Further, the required accuracy in the process “N−1” is “2”, and the required accuracy in the process “N” is “0”. Therefore, as shown in FIG. 5, the allowable range in the process “N” is smaller than the allowable range in the process “N−1”. Therefore, it is more difficult for the process “N” to reach the position of the distal end portion 12a of the robot 10 within the allowable range than for the process “N−1”.

  FIG. 6 is a diagram for explaining the control operation of the robot 10. The robot control unit 116 performs control step by step for each robot control period Δt in the process of controlling the distal end portion 12a of the robot 10 from the position of the process “N-1” to the position of the process “N”. That is, the robot control unit 116 does not set the command value as the target position Pt_N at a time in the process of transition from the process “N−1” to the process “N”, but different command values for each robot control cycle Δt. Control in stages. As the robot control period Δt advances, the command value approaches the target position Pt_N. Here, the robot control cycle Δt is a cycle for controlling the robot 10 and can be determined according to the performance of the CPU 101 of the control device 100. Note that the command value for each robot control period Δt may be included in the operation program.

  Here, the robot 10 that has been used for a long time tends to become uncontrollable according to the command value due to an increase in load resistance accompanying deterioration of the speed reducer or the like. Therefore, when the robot 10 moves during the robot control period Δt, a deviation Δp occurs between the command value pt and the actual value p at time t + Δt. This deviation Δp tends to increase as the robot 10 deteriorates.

  FIG. 7 is a diagram for explaining the difference in cycle time between when the robot 10 is normal and when it is abnormal. FIG. 7 illustrates a state in which the process transitions from the process “N-1” to the process “N”. The time point t when the tip 12a of the robot 10 moves to the reaching position P_N-1 in the process “N-1” and the control in the process “N-1” is completed is time t.

  At the normal time, the tip 12a moves to the position p1 at time t + Δt, moves to the position p2 at time t + 2Δt, and moves to the position p3 at time t + 3Δt. At the third robot control period Δt, the distal end portion 12a reaches a position P_N that is within an allowable range of the process “N”. Therefore, the process cycle time of the process “N” at the normal time is 3Δt.

  On the other hand, at the time of abnormality, the distal end portion 12a moves to the position p1 'at time t + Δt, but there is a deviation between the position p1' and the position p1. Next, the distal end portion 12a moves to the position p2 'at time t + 2Δt, but there is a deviation between the position p2' and the position p2. Next, the tip 12a moves to the position p3 'at time t + 3Δt, but there is a deviation between the position p3' and the position p3.

  Here, at the third robot control cycle Δt, the tip end portion 12a has not yet reached the allowable range of the process “N”. Therefore, the robot control unit 116 controls the robot 10 so that the distal end portion 12a reaches the allowable range at the next robot control cycle Δt. Then, at time t + 4Δt, the position moves to the position p4 ′. At the fourth robot control cycle Δt, the distal end portion 12a reaches a position P_N that is within an allowable range of the process “N”. Therefore, the process cycle time of the process “N” at the time of abnormality is 4Δt.

  Thus, since the required accuracy of the process “N” is “0”, which is the maximum, the allowable range is very small. Therefore, it is not easy for the robot control unit 116 to reach the position of the distal end portion 12a within the allowable range. And it is not easy for the robot 10 that has an abnormality to be controlled so that the robot controller 116 reaches the position of the tip 12a within an allowable range due to an increase in load resistance or the like. The time required for the position 12a to reach the allowable range becomes longer. That is, the process cycle time for the process “N” by the robot 10 in which the abnormality has occurred is longer than the process cycle time for the process “N” by the normal robot 10. The control device 100 according to the first embodiment performs an abnormality diagnosis using such an increase in process cycle time during an abnormality. That is, in the first embodiment, the process cycle time is measured as a physical quantity for the diagnosis target process. Then, the control device 100 according to the first embodiment performs an abnormality diagnosis of the robot 10 using a difference between the measured process cycle time and a reference value of the process cycle time (a normal process cycle time).

  In the process where the required accuracy is not so high, since the allowable range is not so small, even in the robot 10 in which an abnormality has occurred, the robot control unit 116 causes the position of the tip 12a to reach the allowable range. Not so difficult. Therefore, in such a process, it becomes difficult for a difference in process cycle time to occur between an abnormal time and a normal time. That is, in such a process, there is a possibility that an abnormality will not be manifested. In this case, there is a possibility that the abnormality cannot be detected even if the process cycle time is used. On the other hand, the control device 100 according to the first embodiment measures the cycle time in a process with high required accuracy and performs abnormality diagnosis. Therefore, when an abnormality occurs in the robot 10, the process cycle time is longer than that in the normal state. The possibility of stretching increases. That is, abnormalities are easily manifested in a process with high required accuracy. Therefore, the control device 100 according to the first embodiment can detect the abnormality of the robot 10 more reliably.

  That is, a measurement value (cycle time) in a process with high required accuracy is more likely to indicate an abnormality when an abnormality occurs in the robot 10 than a measurement value in a process with low required accuracy. In other words, in a process with high required accuracy, the measured value (cycle time) is likely to differ between when the robot 10 is abnormal and when no abnormality has occurred. Therefore, the control device 100 according to the first embodiment can more reliably detect the abnormality of the robot 10 by performing abnormality diagnosis using the measurement value and the reference value in the process with high required accuracy.

  FIG. 8 is a flowchart of the abnormality diagnosis method performed by the control device 100 according to the first embodiment. The operation program storage unit 112 of the control device 100 stores the operation program (step S102). The diagnosis target process setting unit 114 of the control device 100 sets, as a diagnosis target process, a process “N” whose required accuracy is higher than a predetermined threshold Th1 among a plurality of processes of the operation program (step S104). .

  Next, the robot control unit 116 of the control device 100 controls the robot 10 according to the operation program (step S110). The process of S110 will be described in detail with reference to FIG. Next, the control device 100 performs an abnormality diagnosis based on the measured value obtained by measuring the physical quantity for the diagnosis target process for the process “N” that is the diagnosis target process (step S20). The process of S20 will be described in detail with reference to FIG.

  FIG. 9 is a flowchart showing the robot control process (S110) in the flowchart shown in FIG. First, the robot control unit 116 initializes the process “K” to be controlled, that is, K = 1 (step S112). Next, the robot control unit 116 starts the operation of the process “K” (step S114), and controls the robot 10 so that the position of the tip 12a of the robot 10 approaches the target position Pt_K of the process “K”. (Step S116).

  The robot controller 116 determines whether or not the actual position P of the distal end portion 12a has converged within the allowable range of the process “K” (step S118). Specifically, the robot control unit 116 determines whether or not the difference between the actual position P and the target position Pt_K is within the allowable range of the process “K”. If it is determined that the actual position P of the tip 12a has not converged within the allowable range of the process “K” (NO in S118), the process returns to S116. On the other hand, when it is determined that the actual position P of the distal end portion 12a has converged within the allowable range of the process “K” (YES in S118), the robot control unit 116 ends the control in the process “K” ( Step S120).

  Next, the robot control unit 116 determines whether or not the last step in the operation program has been completed, that is, whether or not K = M (step S122). When it is determined that the last process is not completed (NO in S122), the robot control unit 116 increments K by 1 (step S124), and repeats the processes of S114 to S122 for the next process. On the other hand, when it is determined that the last process is completed, that is, K = M (YES in S122), the robot control unit 116 ends the control of the robot 10 in the operation program (Step S126).

FIG. 10 is a flowchart showing the abnormality diagnosis process (S20) in the flowchart shown in FIG. First, the working time measurement unit 120 of the control device 100 performs a process cycle time from the end time of the process “N-1” immediately before the process “N”, which is the diagnosis target process, to the end time of the process “N”. T is measured (step S202). Next, the abnormality diagnosis unit 124 of the control device 100 acquires a reference process cycle time Ts from the measurement value management unit 122 (step S204). Next, the abnormality diagnosis unit 124 of the control device 100 calculates an increase rate R [%] of the process cycle time (step S206). Here, the process cycle time increase rate R is expressed by the following equation.
R = ((T−Ts) / Ts) * 100

  Next, the abnormality diagnosis unit 124 of the control device 100 determines whether or not the process cycle time increase rate R is greater than a predetermined threshold A (step S208). When it is determined that the process cycle time increase rate R is equal to or less than the threshold A (NO in S208), the abnormality diagnosis unit 124 determines that no abnormality has occurred in the robot 10 (step S210). On the other hand, when it is determined that the process cycle time increase rate R is greater than the threshold value A (YES in S208), the abnormality diagnosis unit 124 determines whether or not the process cycle time increase rate R is smaller than a predetermined threshold value B. Is determined (step S212). Here, B> A.

  When it is determined that the process cycle time increase rate R is smaller than the threshold value B (YES in S212), the abnormality diagnosis unit 124 determines that a slight abnormality has occurred in the robot 10 (step S214). At this time, the warning output unit 126 outputs a mild warning (step S216). For example, the warning output unit 126 may turn on a yellow lamp. On the other hand, when it is determined that the process cycle time increase rate R is greater than or equal to the threshold value B (NO in S212), the abnormality diagnosis unit 124 determines that a serious abnormality has occurred in the robot 10 (step S218). At this time, the robot 10 is in an abnormal end state and needs to be promptly repaired. At this time, the warning output unit 126 outputs a severe warning (step S220). For example, the warning output unit 126 may turn on a red lamp.

  By measuring the process cycle time in a process to be diagnosed with high required accuracy, the process cycle time increase rate R increases more reliably when an abnormality occurs in the robot 10. Therefore, the control device 100 according to the first embodiment can detect the abnormality of the robot 10 more reliably.

  That is, the measurement values (process cycle time and process cycle time increase rate R) in a process with high required accuracy are more likely to indicate an abnormality when an abnormality occurs in the robot 10 than measurement values in a process with low required accuracy. In other words, in a process with high required accuracy, the measured values (process cycle time and process cycle time increase rate R) are likely to differ between when the robot 10 has an abnormality and when no abnormality has occurred. Therefore, the control device 100 according to the first embodiment can more reliably detect the abnormality of the robot 10 by performing abnormality diagnosis using the measurement value in the process with high required accuracy.

(Modification)
Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, the order of the steps in the flowcharts shown in FIGS. 8 to 10 can be changed as appropriate. Also, one or more of the steps in the flowchart may be omitted.

  For example, in FIG. 10, the processes of S210 to S220 may be omitted. Then, when the determination in S208 is YES, processing for outputting a warning may be performed. Moreover, the process of S202 of FIG. 10 may be performed during the process of S110. That is, the measurement of the cycle time may be performed when the diagnosis target process is executed and the robot 10 is controlled.

  For example, the process of S104 of FIG. 8 may be performed after the process of S110. In this case, it is necessary to measure all process cycle times in each process since which process is the diagnosis target process after all the control processes of the robot 10 are completed. On the other hand, as shown in FIG. 8, by setting the diagnosis target process before the control of the robot 10, it is only necessary to measure only the process cycle time related to the preset diagnosis target process.

  In the above-described embodiment, the abnormality diagnosis is performed using only the cycle time (process cycle time) in the process with high required accuracy. However, the present invention is not limited to such a configuration. The abnormality diagnosis may be performed using not only a process with high required accuracy but also a cycle time in one or more processes before and after the process. For example, in the example of FIG. 3, abnormality diagnosis may be performed using the work time (cycle time) from the start of the process “1” to the end of the process “N”.

  On the other hand, in this case, the measured cycle time includes the working time in the process “2” and the process “3” in which the robot 10 operates in cooperation with or in cooperation with another device (or worker). The work time in the process “2” and the process “3” may be affected by work on other devices (or workers). As a result, even if the cycle time increases, the cause of the increase may not be due to the abnormality of the robot 10 to be diagnosed, but may be due to another device (or operator). Therefore, using the measurement value obtained by measuring the cycle time (process cycle time) only in the process with high required accuracy, that is, the time from the end of the process before the diagnosis target process to the end of the diagnosis target process. By performing the abnormality diagnosis, it is possible to eliminate the influence of other devices or the like on the measured cycle time. Therefore, it is possible to detect the abnormality of the robot 10 more reliably.

  In the above-described embodiment, the abnormality diagnosis is performed using the process cycle time increase rate R, but the configuration is not limited thereto. For example, an abnormality may be determined when the value of T / Ts becomes larger than a predetermined threshold value.

  In the above-described embodiment, the abnormality diagnosis is performed by measuring the cycle time including the time until the difference between the position of the control target of the robot 10 and the target position falls within the allowable range. It is not restricted to such a configuration. For example, the abnormality diagnosis may be performed using a probability that the difference between the position of the control target of the robot 10 and the target position is within an allowable range within a predetermined time limit. In this case, the probability of the normal robot 10 is higher than the probability of the robot 10 in which an abnormality has occurred. Moreover, the tendency becomes more remarkable in the probability in the process with high required accuracy. In other words, in a process with low required accuracy, there may be little difference between the probability in the normal robot 10 and the probability in the robot 10 in which an abnormality has occurred, but in the process with high required accuracy, the probability in the normal robot 10 And the probability of the robot 10 in which an abnormality has occurred can be significantly different. That is, the control device 100 in this example is also abnormal using the measured value (probability in the robot 10 in which an abnormality may occur) and the reference value (probability in the normal robot 10) in a process with high required accuracy. By performing the diagnosis, it is possible to detect the abnormality of the robot 10 more reliably.

  In the above-described embodiment, the abnormality diagnosis is performed using the cycle time (process cycle time). However, the configuration is not limited thereto. The abnormality diagnosis may be performed by using an arbitrary physical quantity that may vary with an abnormality of the robot 10 as a physical quantity for the diagnosis target process, instead of the cycle time.

  Further, for example, abnormality diagnosis may be performed using the arrival deviation amount ΔP shown in FIG. Specifically, when the allowable range in the process to be diagnosed is ± ΔA, the abnormality diagnosis unit 124 calculates an arrival deviation amount increase rate D (= (ΔP / ΔA) * 100) [%]. Then, the abnormality diagnosis unit 124 may determine that an abnormality has occurred in the robot 10 when the arrival deviation amount increase rate D is larger than a predetermined threshold value (reference value). Since the allowable range ΔA is small in the process to be diagnosed, the reaching deviation amount increase rate D can be large even if the reaching deviation amount ΔP is small. The arrival deviation amount ΔP can be large when the robot 10 is abnormal. Therefore, even if the arrival deviation amount ΔP is used as a measurement value in a process with high required accuracy, it is possible to detect the abnormality of the robot 10 more reliably.

  That is, also in this example, the measured values (reached deviation amount ΔP and the reached deviation amount increase rate D) in the process with high required accuracy are higher when the abnormality occurs in the robot 10 than the measured values in the process with low required accuracy. It is easy to show abnormality. In other words, in a process with high required accuracy, the measured values (reaching deviation amount ΔP and reaching deviation amount increase rate D) tend to differ between when the robot 10 is abnormal and when no abnormality is occurring. Therefore, the control device 100 in this example also detects the abnormality of the robot 10 more reliably by performing abnormality diagnosis using the measurement value and the reference value (predetermined threshold value) in the process with high required accuracy. Is possible.

  On the other hand, even if a slight abnormality that does not need to be taken into consideration occurs in the robot 10, there is a possibility that the reaching deviation amount increase rate D becomes large. On the other hand, the cycle time (working time) can become longer as the degree of abnormality of the robot 10 increases. Therefore, it is possible to detect the abnormality of the robot 10 more reliably by performing the abnormality diagnosis using the cycle time.

  In the above-described embodiment, the operation program for performing abnormality diagnosis is a program (teaching data) used for work in an actual actual machine line, but is not limited to such a configuration. An abnormality diagnosis program may be prepared separately, and abnormality diagnosis may be performed using the program. However, by performing abnormality diagnosis in a process with high required accuracy in a program used for work on an actual actual machine line, it is not necessary to prepare a separate abnormality diagnosis program. In addition, when a program used for actual work does not include a process with high required accuracy, a process with high required accuracy may be intentionally inserted into the operation program.

  In the above-described embodiment, the diagnosis target process setting unit 114 sets only the process “N” having high required accuracy as the diagnosis target process, but the configuration is not limited thereto. The diagnosis target process setting unit 114 may set the process “N-1” immediately before the process “N” as a diagnosis target process for designating the start of the cycle time. As described above, the process “N-1” and the process “N” are set as the diagnosis target processes, so that the work time measurement unit 120 sets the end time of the process “N-1” as the cycle time measurement start time. This can be easily determined.

  In the above-described embodiment, the diagnosis target process setting unit 114 sets only one process “N” having a high required accuracy as the diagnosis target process, but the configuration is not limited thereto. When there are a plurality of processes with high required accuracy (processes with accuracy “0”), the diagnosis target process setting unit 114 may set a plurality of processes with high required accuracy as the diagnosis target processes. In this case, abnormality diagnosis is performed for a plurality of diagnosis target processes. In this case, a warning may be output when it is determined that there is an abnormality in at least one of the plurality of abnormality diagnoses, or a warning may be output when all of the plurality of abnormality diagnoses are determined to be abnormal. . Further, different warnings may be output depending on the number of items determined to be abnormal in a plurality of abnormality diagnoses.

  In the above-described embodiment, the control device 100 controls the “position” of the control target of the robot 10 (for example, the front end portion 12a of the robot 10), and the “target position” is the front end portion 12a that is the control target. However, the present invention is not limited to such a configuration. Controlling the “position” of the control object of the robot 10 not only controls the robot 10 so that the position of the control object of the robot 10 moves to a desired position in the three-dimensional space, but also the position of the control object. It may include controlling the robot 10 so that the posture of the portion related to the above becomes a desired posture. Therefore, the “position” may include not only the position coordinates (x, y, z) in the three-dimensional space but also the posture (direction) (roll, pitch, yaw). Furthermore, the “target position” may include not only a desired position coordinate in the three-dimensional space but also a desired posture (orientation). In this case, the difference between the target position and the actual position may be considered separately for the difference in position coordinates and the difference in posture. Then, the control device 100 may control the robot 10 so that the difference between both falls within the respective allowable ranges.

  In the above-described example, the program can be stored using various types of non-transitory computer readable media and supplied to the computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media are magnetic recording media (eg flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (eg magneto-optical disks), CD-ROM, CD-R, CD-R / W. Semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM). The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

DESCRIPTION OF SYMBOLS 1 Robot control system, 10 Robot, 12a Tip part, 14 joints, 100 control apparatus, 112 Operation program storage part, 114 Diagnosis object process setting part, 116 Robot control part, 118 Actual position acquisition part, 120 Working time measurement part, 122 Measurement value management unit, 124 abnormality diagnosis unit, 126 warning output unit, 200 operation program

Claims (4)

An abnormality diagnosis method for diagnosing abnormality of a robot that operates by driving a joint, wherein the robot is controlled by an operation program composed of a plurality of steps each associated with a predetermined target position and required accuracy. And
The process in which the required accuracy is higher than a predetermined value among the plurality of processes is set as a diagnosis target process,
Using the operation program, control is performed so that the difference between the position of the control target of the robot and the target position is within an allowable range related to the required accuracy in the diagnosis target step,
An abnormality diagnosis method for a joint-driven robot that performs abnormality diagnosis of the robot using a measurement value for the diagnosis target process and a reference value related to the measurement value. Measuring an operation time required for at least one process including the diagnosis target process;
The abnormality diagnosis method for the joint-driven robot according to claim 1, wherein abnormality diagnosis of the robot is performed using a difference between the measured work time and a reference value of the work time. The joint drive robot abnormality diagnosis method according to claim 2, wherein a time from the end of the process before the diagnosis target process to the end of the diagnosis target process is measured as the work time. An abnormality diagnosis apparatus for diagnosing an abnormality of a robot that operates by driving a joint, wherein the robot is controlled by an operation program configured by a plurality of steps each associated with a predetermined target position and required accuracy. And
A setting means for setting the process having a required accuracy higher than a predetermined value among the plurality of processes as a process to be diagnosed;
Using the operation program, when the control is performed so that the difference between the position of the control target of the robot and the target position is within an allowable range related to the required accuracy in the diagnosis target step, the diagnosis target step An abnormality diagnosis apparatus for a joint-driven robot, comprising: a diagnosis unit that performs an abnormality diagnosis of the robot using a measurement value for the reference value and a reference value related to the measurement value.

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