robot systems

Abstract

We provide a robotic system that can reduce the effort required to diagnose abnormalities. [Solution] The robot system 100 includes a diagnostic section identification unit 113 that identifies a diagnostic section from a set of instructions in a work program, based on data collected by executing a work program for a robot having joints, from a diagnostic start point to a diagnostic end point, which is a section for diagnosing abnormalities in the robot, and a diagnostic section addition unit 114 that adds the identified diagnostic section to the work program so that it can be identified as a diagnostic section.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 below discloses a method for diagnosing an abnormality of a robot that operates by driving joints of a robot arm. In this method, a diagnostic target process to be diagnosed is preset from among a plurality of processes constituting an operation program. Then, an abnormality of the robot is diagnosed by comparing a measured value measured when executing the set diagnostic target process with a reference value. In this method, an operator registers the high operation accuracy required in each process, and a process with a high required operation accuracy is set as the diagnostic target process.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when diagnosing an abnormality of a robot, depending on the measured value used for the diagnosis, if the measurement is not performed with the operation and speed optimal for the diagnosis, the abnormality of the robot may not be detected. However, in order to determine such operating conditions, it is necessary to sufficiently acquire knowledge about the structure of the robot. That is, a great deal of labor is required to correctly diagnose an abnormality of the robot.

[0005] Therefore, an object of the present invention is to provide a robot system capable of reducing the labor for diagnosing an abnormality.

Means for Solving the Problems

[0006] A robot system according to one aspect of the present invention includes a diagnostic section identification unit that identifies a diagnostic section from a set of instructions in a work program, based on data collected by executing a work program for an industrial robot, from a diagnostic start point to a diagnostic end point, which is a section for diagnosing abnormalities in an industrial robot; and a diagnostic section addition unit that adds the identified diagnostic section to the work program so that it can be identified as a diagnostic section.

[0007] According to this embodiment, when identifying a diagnostic interval for diagnosing a robot abnormality from a set of instructions in a work program, the diagnostic interval can be identified using data collected by actually executing the work program in advance through simulation, and the identified diagnostic interval can be added to the work program so that it can be identified as a diagnostic interval.

[0008] This makes it possible to diagnose robot abnormalities based on data measured between the start and end points of a diagnosis when executing a work program with a distinguishable diagnostic interval.

[0009] In the above embodiment, the collected data may include either the motor position of each axis of the industrial robot or the motor current value of each axis of the industrial robot, and the diagnostic section identification unit may identify as a diagnostic section any section in which it determines that any axis of the industrial robot is performing a reversal operation based on either the collected motor position or motor current value.

[0010] According to this embodiment, abnormalities in the robot can be diagnosed based on data measured in the section in which any axis of the robot is performing a turning motion. This makes it possible to monitor for abnormalities caused by backlash that may occur in conjunction with the turning motion of the axis.

[0011] In the above embodiment, the data collected includes the motor current values ​​of each axis of the industrial robot, and the diagnostic section identification unit may identify as a diagnostic section a section in which it has determined that the motor current values ​​are measured at a predetermined ratio or less to the rated current, based on the collected motor current values.

[0012] According to this embodiment, abnormalities in the robot can be diagnosed based on data measured in a section where the motor current value is measured at or below a predetermined ratio to the rated current. This makes it possible to monitor for abnormalities in the robot using data measured when the robot is operating at low or medium speeds or lower, where changes in the motor current value are relatively small.

[0013] In the above embodiment, the collected data includes either the content of a movement command defined in the work program or the content of a work command defined in the work program, and the diagnostic section identification unit may identify as a diagnostic section any section in which it determines that the industrial robot is performing work at a constant speed, based on either the content of the movement command or the content of the work command collected.

[0014] According to this embodiment, abnormalities in the robot can be diagnosed based on data measured in sections where the robot is performing work at a constant speed. This makes it possible to monitor for abnormalities in the robot using data measured under relatively stable working conditions.

[0015] In the above embodiment, the system may further include a program execution unit that executes a work program, and a diagnostic unit that, if the work program executed by the program execution unit includes a diagnostic section, acquires the motor current values ​​of each axis of the industrial robot operating during the diagnostic section and diagnoses whether or not there is an abnormality in the robot based on the acquired motor current values.

[0016] According to this aspect, when executing a work program provided with a diagnosis section, it is possible to acquire the motor current value of each axis of the robot operating during the diagnosis section, and it becomes possible to monitor the presence or absence of an abnormality of the robot using the acquired motor current value.

[0017] In the above aspect, when diagnosing the presence or absence of an abnormality of an industrial robot, the diagnosis unit may calculate any one of the average value, peak value, and standard deviation of the acquired motor current value, and when the calculated value exceeds a predetermined threshold value, determine that the industrial robot is abnormal.

[0018] According to this aspect, it becomes possible to monitor the presence or absence of an abnormality of the robot using the fluctuation state of any one of the average value, peak value, and standard deviation of the motor current value acquired during the diagnosis section.

[0019] In the above aspect, the diagnosis unit may correct the acquired motor current value by at least any one of the encoder temperature of each axis of the industrial robot and the rotational speed of each axis of the industrial robot, and calculate any one of the average value, peak value, and standard deviation using the corrected motor current value.

[0020] According to this aspect, it becomes possible to monitor the presence or absence of an abnormality of the robot in a state where the accuracy of the motor current value used for diagnosis is improved. Thereby, it becomes possible to further improve the accuracy of the abnormality diagnosis of the robot.

Effect of the Invention

[0021] According to the present invention, it is possible to provide a robot system capable of reducing the labor for diagnosing an abnormality.

Brief Description of the Drawings

[0022] [Figure 1] It is a diagram illustrating the configuration of a robot system according to an embodiment. [Figure 2] It is a diagram illustrating the functional configuration of the robot control device shown in FIG. 1. [Figure 3]It is a flowchart for explaining an example of the operation of a robot system.

Embodiments for Carrying out the Invention

[0023] Referring to the accompanying drawings, preferred embodiments of the present invention will be described. In each figure, those with the same reference numerals have the same or similar configurations. Also, since the drawings are schematic, the dimensions and ratios of each component are different from the actual ones.

[0024] FIG. 1 is a diagram illustrating the configuration of a robot system 100 according to an embodiment. The robot system 100 includes, for example, a robot control device 1, a manipulator (robot) 2, and an input / output terminal 3.

[0025] The robot control device 1 and the manipulator 2, and the robot control device 1 and the input / output terminal 3 are respectively connected via a network. The network may be by wireless communication such as WiFi (Wireless Fidelity), or may be by wired communication such as a communication cable.

[0026] Note that a teach pendant may be included in the robot system 100. The teach pendant can be connected to the robot control device 1 and is an operating device used when an operator teaches the operation of the manipulator 2.

[0027] [[ID=2,4]]

[0028] ​The robot control device 1 is a control unit that controls the operation of the manipulator 2. The robot control device 1 includes, for example, a control unit 11, a storage unit 12, and a communication unit 13.

[0029] The control unit 11 is a processor and controls the manipulator 2 by executing the work program stored in the memory unit 12. The control unit 11 also edits the work program by executing programs such as a program to identify the diagnostic section (described later) stored in the memory unit 12 and add it to the work program.

[0030] The memory unit 12 is a computer-readable recording medium that stores programs for realizing various functions of the robot control device 1 and various data used in those programs. These various data include, for example, work programs, collected data (described later), and diagnostic data.

[0031] The communication unit 13 is a communication interface that controls communication with the manipulator 2 and input / output terminal 3 connected via the network.

[0032] The robot control device 1 may further include a welding power supply unit. The welding power supply unit supplies welding current, welding voltage, etc., to the manipulator 2 according to predetermined welding conditions in order to generate an arc between the tip of the welding wire and the workpiece. The welding power supply unit may be provided separately from the robot control device 1.

[0033] The input / output terminal 3 is a terminal device used by an operator, and includes, for example, an input device such as a keyboard or mouse, and a display device such as a display. The input / output terminal 3 may also be a display device having a touch panel.

[0034] Figure 2 illustrates the functional configuration of the robot control device 1. The robot control device 1 includes, for example, a program execution unit 111, a data acquisition unit 112, a diagnostic interval identification unit 113, a diagnostic interval addition unit 114, a diagnostic unit 115, and a diagnostic result output unit 116. The robot control device 1 does not need to possess all of these functions; some functions may be distributed to other devices. Each function is described below.

[0035] The program execution unit 111 executes the work program stored in the storage unit 12. The work program consists of a set of instructions, such as a movement instruction and a welding instruction.

[0036] The data acquisition unit 112 collects data such as current values, teaching points, and commands while the program execution unit 111 is executing the work program. The data acquisition unit 112 stores the collected data as collected data in the storage unit 12.

[0037] The collected data may include, for example, the motor current command for each axis, the motor current value for each axis, the motor position command for each axis, the motor position (encoder value) for each axis, the encoder temperature for each axis, the rotational speed for each axis, the welding torch tip position command, the welding torch tip position, the teaching points of the work program, the contents of the movement commands of the work program, and the contents of the welding commands of the work program.

[0038] In the work program's movement commands, for example, linear interpolation and circular interpolation can be set as the interpolation type when interpolating between teaching points. These linear and circular interpolation commands are movement commands that weld between teaching points while moving the welding torch at a constant speed. In the work program's welding commands, for example, the welding speed can be set. When the welding speed is set, the welding torch will move at a constant speed at the set speed.

[0039] Furthermore, the data collected by the data acquisition unit 112 is not limited to data obtained when the work program is executed and the manipulator 2 is actually operated. For example, data obtained when the work program is executed through simulation may also be used as the collected data.

[0040] The diagnostic section identification unit 113 identifies a diagnostic section from the set of instructions of the work program based on the collected data obtained by executing the work program. The diagnostic section is a section for diagnosing abnormalities in the manipulator 2, and is defined by setting a diagnostic start point and a diagnostic end point in the set of instructions of the work program. Multiple diagnostic sections may be provided for each work program, and diagnostic sections may overlap.

[0041] It is preferable to identify the following intervals (1) to (3) as diagnostic intervals.

[0042] (1) Section in which the axis of the multi-joint arm performs a folding motion: When the axis of the articulated arm reverses direction, the rotation direction of the reduction gear reverses. The reduction gear has a gap between the gears that allows for play when the gears are meshed (hereinafter also referred to as "backlash"). If this backlash becomes large, it will affect the precision and vibration of manipulator 2.

[0043] Therefore, monitoring changes in backlash is an effective way to detect abnormalities in manipulator 2. The reversal of the shaft's rotation direction makes it easier to detect these changes in backlash, making this reversal motion a suitable diagnostic section.

[0044] The diagnostic section identification unit 113 identifies a section in which it determines that one of the axes of the manipulator 2 is performing a reversal operation, based on either the motor position of each axis or the motor current value of each axis collected by the data acquisition unit 112, as a diagnostic section. For example, it determines that an axis has reversed when the direction of movement of the motor position reverses, or when the sign of the motor current value reverses.

[0045] (2) Sections in which manipulator 2 is not operating at high speed: When manipulator 2 is operating at high speed, the motor current value increases. When the motor current value increases, the change in the motor current value per sampling period also tends to increase. In other words, during high-speed operation, the change in the motor current value tends to be large.

[0046] In contrast, diagnosing manipulator 2 requires measuring minute changes in the motor current value. Therefore, the diagnostic interval is suitable when the motor is operating at low or medium speed or lower, where changes in the motor current value are relatively small, i.e., when it is not operating at high speed.

[0047] The condition that the motor is not operating at high speed should preferably be determined appropriately based on the rated current, for example, by specifying that the motor current value is less than or equal to XX% of the rated current. Note that the rated current may differ for each shaft.

[0048] The diagnostic section identification unit 113 identifies a section as a diagnostic section based on the motor current values ​​of each axis collected by the data acquisition unit 112, in which it determines that the motor current value is measured at a predetermined ratio or less to the rated current. For example, if the motor current value is approximately 50% or less of the rated current, it is determined that the motor is not operating at high speed.

[0049] (3) Sections where manipulator 2 is welding at a constant speed: In welding operations, the positioning accuracy of the welding start point (teaching point) and welding end point (teaching point) is high. Therefore, the welding start point and welding end point are locations where measurement errors are less likely to occur when performing diagnostics. Consequently, the section between the welding start point and welding end point, where welding is performed at a constant speed, is a section in which diagnostic data can be measured under relatively stable working conditions, making it suitable as a diagnostic section.

[0050] The diagnostic section identification unit 113 identifies a section in which the welding torch of the manipulator 2 is determined to be welding at a constant speed, based on either the content of the movement command or the welding command of the work program collected by the data acquisition unit 112, as a diagnostic section. For example, it determines that welding is occurring at a constant speed if the interpolation type included in the movement command of the work program is linear interpolation or circular interpolation, or if a welding speed is set in the welding command of the work program.

[0051] The diagnostic interval addition unit 114 adds the identified diagnostic interval to the work program so that it can be identified as a diagnostic interval. Alternatively, the diagnostic interval of the work program may be stored in the storage unit 12 separately from the work program. In this case, when executing the work program, the diagnostic interval may be identified by reading the diagnostic interval stored in the storage unit 12.

[0052] The diagnostic unit 115 acquires the motor current values ​​of each axis of the manipulator 2 that is operating during the diagnostic section if the work program being executed by the program execution unit 111 includes a diagnostic section. Based on the acquired motor current values, the diagnostic unit 115 diagnoses whether or not there is an abnormality in the manipulator 2.

[0053] When diagnosing whether there is an abnormality in the manipulator 2, the diagnostic unit 115 calculates either the average value, peak value, or standard deviation of the acquired motor current value. The diagnostic unit 115 then determines that there is an abnormality in the manipulator 2 if the calculated value exceeds a predetermined threshold for abnormality determination.

[0054] Here, the diagnostic unit 115 may correct the motor current values ​​used in the calculation before calculating the average value, peak value, and standard deviation of the motor current values. Specifically, it is preferable that the diagnostic unit 115 corrects the acquired motor current values ​​using at least one of the encoder temperature of each axis of the manipulator 2 and the rotational speed of each axis of the manipulator 2.

[0055] Furthermore, the data used to diagnose whether or not there is a malfunction in manipulator 2 is not limited to motor current values; any measurement data that can be used to determine whether or not there is a malfunction can be used as appropriate.

[0056] The diagnostic unit 115 stores the data used for diagnosis and the diagnostic results as diagnostic data in the storage unit 12. The diagnostic results may include whether or not there is an abnormality and the nature of the abnormality.

[0057] The diagnostic result output unit 116 outputs the diagnostic result from the diagnostic unit 115 to the input / output terminal 3. For example, if the diagnostic result from the diagnostic unit 115 indicates an abnormality, it may send a message indicating the abnormality to the input / output terminal 3. The input / output terminal 3 may display the message on a display or output the message or alarm sound from a speaker.

[0058] Referring to Figure 3, an example of the operation of the robot system 100 will be described.

[0059] First, the program execution unit 111 executes the work program stored in the storage unit 12 (step S101).

[0060] Next, the program execution unit 111 determines whether or not a diagnostic section exists in the work program (step S102). If this determination is YES (step S102; YES), the process proceeds to step S106, which will be described later.

[0061] If it is determined in step S102 that there is no diagnostic section in the work program (step S102; NO), the data acquisition unit 112 acquires collected data such as current values, teaching points, and commands while the work program is being executed (step S103).

[0062] Next, the diagnostic interval identification unit 113 identifies a diagnostic interval from the set of instructions of the work program based on the collected data collected in step S103 (step S104).

[0063] Next, the diagnostic interval addition unit 114 adds the diagnostic interval identified in step S104 to the work program so that it can be identified as a diagnostic interval (step S105). Then, this operation ends.

[0064] If it is determined in step S102 that a diagnostic section exists in the work program (step S102; YES), the diagnostic unit 115 diagnoses the manipulator 2 based on the motor current values ​​of each axis of the manipulator 2 that are operating during the diagnostic section (step S106).

[0065] Next, the diagnostic unit 115 determines whether there is an abnormality in the manipulator 2 based on the diagnostic result of step S106 (step S107). If this determination is NO (step S107; NO), this operation is terminated.

[0066] If the manipulator 2 is determined to be faulty in step S107 (step S107; YES), the diagnostic result output unit 116 sends a message indicating the fault to the input / output terminal 3 (step S108). Then, this operation ends.

[0067] As described above, according to the robot system 100 of the embodiment, when identifying a diagnostic section for diagnosing an abnormality in the manipulator 2 from the set of instructions in the work program, the diagnostic section can be identified using collected data obtained by actually executing the work program in advance or by simulation, and the identified diagnostic section can be added to the work program so that it can be identified as a diagnostic section.

[0068] This makes it possible to diagnose robot abnormalities based on data measured between the start and end points of a diagnosis when executing a work program with a distinguishable diagnostic interval.

[0069] Therefore, according to the robot system 100 of this embodiment, it is possible to reduce the effort required to diagnose abnormalities.

[0070] It should be noted that the present invention is not limited to the embodiments described above, and can be implemented in various other forms without departing from the spirit of the invention. For this reason, the above embodiments are merely illustrative in all respects and should not be interpreted restrictively. For example, the order of each processing step described above can be arbitrarily changed or executed in parallel, as long as there is no inconsistency in the processing content.

[0071] Furthermore, although the embodiments described above used a welding robot, the present invention is not limited to this. The present invention can be applied to industrial robots, including handling robots that perform picking and other operations, and cutting and polishing robots that perform cutting and polishing operations. In this case, the welding target, welding operation, and welding command used in the above embodiments can be appropriately replaced with the work target, work, and work command, respectively. [Explanation of Symbols]

[0072] 1...Robot control device, 2...Manipulator, 3...Input / output terminal, 11...Control unit, 12...Storage unit, 13...Communication unit, 100...Robot system, 111...Program execution unit, 112...Data acquisition unit, 113...Diagnostic section identification unit, 114...Diagnostic section addition unit, 115...Diagnostic unit, 116...Diagnostic result output unit

Claims

1. A diagnostic section identification unit identifies a diagnostic section from a set of instructions in the work program, based on data collected by executing a work program for an industrial robot, which is a section for diagnosing an abnormality in the industrial robot, from a diagnostic start point to a diagnostic end point. A diagnostic interval addition unit is added to the work program so that the identified diagnostic interval can be identified as the diagnostic interval, A robotic system equipped with the following features.

2. The collected data includes either the motor position of each axis of the industrial robot or the motor current value of each axis of the industrial robot. The diagnostic section identification unit identifies a section in which it has determined, based on either the collected motor position or the motor current value, that any axis of the industrial robot is performing a reversal motion, as the diagnostic section. The robot system according to claim 1.

3. The data collected includes the motor current values ​​for each axis of the industrial robot. The diagnostic section identification unit identifies a section in which it has determined, based on the collected motor current value, that the motor current value is measured at a predetermined ratio or less to the rated current, as the diagnostic section. The robot system according to claim 1.

4. The collected data includes either the contents of a movement command defined in the work program or the contents of a work command defined in the work program. The diagnostic section identification unit identifies a section in which it has determined that the industrial robot is performing work at a constant speed, based on either the content of the collected movement command or the content of the work command, as the diagnostic section. The robot system according to claim 1.

5. A program execution unit that executes the aforementioned work program, When the work program executed by the program execution unit includes the diagnostic section, the diagnostic unit acquires the motor current values ​​of each axis of the industrial robot operating during the diagnostic section and diagnoses whether or not there is an abnormality in the industrial robot based on the acquired motor current values. The robot system according to claim 1, further comprising:

6. The diagnostic unit, when diagnosing whether or not there is an abnormality in the industrial robot, calculates either the average value, peak value, or standard deviation of the acquired motor current value, and determines that the industrial robot is abnormal if the calculated value exceeds a predetermined threshold. The robot system according to claim 5.

7. The diagnostic unit corrects the acquired motor current value using at least one of the encoder temperature of each axis of the industrial robot and the rotational speed of each axis of the industrial robot, and uses the corrected motor current value to calculate one of the average value, peak value, or standard deviation. The robot system according to claim 6.

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