Robot diagnostic device, robot diagnostic method, and robot diagnostic program

Abstract

To highly precisely predict a remaining service life of a drive unit of a robot.SOLUTION: A robot diagnosis system 1 diagnoses a condition of a drive unit 321 of a robot 3 including the drive unit 321 having a motor 322. The robot diagnosis system 1 includes an acquisition unit 131 that acquires a current command value for a predetermined time to be issued to the motor 322, a generation unit 132 that extracts a specific frequency component which is equal to or higher than a first frequency from the current command value acquired by the acquisition unit 131, amplifies the specific frequency component, superimposes the amplified specific frequency component to frequency components equal to or lower than the first frequency of the current command value, and thus generates an evaluation current, and a prediction unit 133 that predicts failure timing, according to which the drive unit 321 fails, on the basis of a time-sequence change tendency of the evaluation current generated by the generation unit 132.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology disclosed herein relates to a robot diagnostic apparatus, a robot diagnostic method, and a robot diagnostic program.

Background Art

[0002] For example, due to long-term use of an industrial robot, deterioration (e.g., wear of gears in a speed reducer) occurs in devices constituting a drive unit that drives a robot arm or the like, and as a result, the operation accuracy of the robot decreases. If such a state is left unattended, the devices constituting the drive unit will be damaged and the robot will malfunction. Then, for example, the production line in a factory will stop and productivity will decrease. Therefore, for example, Patent Document 1 collects data of a robot controller in actual work via a communication line, and performs failure diagnosis and maintenance based on the collected data.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, with the technology disclosed in Patent Document 1, it is possible to determine the necessity of maintenance such as part replacement at the current time based on the current data, but it is impossible to specify the time when maintenance will be required in the future. That is, with the technology disclosed in Patent Document 1, it is difficult to plan in advance a robot maintenance schedule with a margin. Therefore, there is a problem that it is difficult to perform robot maintenance in a timely manner.

[0005] The technology disclosed herein has been developed in view of these points, and its purpose is to accurately predict the remaining lifespan of the robot's drive unit. [Means for solving the problem]

[0006] The robot diagnostic device disclosed herein diagnoses the state of a drive unit of a robot that includes a motor. The robot diagnostic device comprises an acquisition unit, a generation unit, and a prediction unit. The acquisition unit acquires current command values ​​for the motor for a predetermined time. The generation unit extracts specific frequency components of a first frequency or higher from the current command value acquired by the acquisition unit, amplifies the specific frequency components, and generates an evaluation current superimposed on the current command value. The prediction unit predicts the failure time at which the drive unit will fail based on the time-series change trend of the evaluation current generated by the generation unit.

[0007] Another robot diagnostic device disclosed herein diagnoses the state of a drive unit of a robot that includes a motor. The robot diagnostic device comprises an acquisition unit, a generation unit, and a prediction unit. The acquisition unit acquires current command values ​​for the motor for a predetermined time. The generation unit extracts specific frequency components of the current command value acquired by the acquisition unit that are at or above a first frequency, amplifies the specific frequency components, and generates an evaluation current by superimposing them on the frequency components of the current command value that are at or below the first frequency. The prediction unit predicts the failure time at which the drive unit will fail based on the time-series change trend of the evaluation current generated by the generation unit.

[0008] Furthermore, the robot diagnostic method disclosed herein is a method for diagnosing the state of a drive unit of a robot that includes a motor. The robot diagnostic method includes obtaining a current command value for the motor for a predetermined time, extracting specific frequency components of the current command value with a first frequency or higher, amplifying the specific frequency components and superimposing them on the current command value to generate an evaluation current, and predicting the failure time at which the drive unit will fail based on the time-series change trend of the evaluation current.

[0009] Another robot diagnostic method disclosed herein is a method for diagnosing the state of a drive unit of a robot that includes a motor. The robot diagnostic method includes: obtaining a current command value for the motor for a predetermined time; extracting specific frequency components of the current command value that are at or above a first frequency; amplifying the specific frequency components and superimposing them on frequency components of the current command value that are at or below the first frequency to generate an evaluation current; and predicting the failure time at which the drive unit will fail based on the time-series change trend of the evaluation current.

[0010] Furthermore, the robot diagnostic program disclosed herein enables a computer to perform a function to diagnose the state of a drive unit of a robot that includes a motor. The robot diagnostic program enables a computer to perform a function to acquire a current command value for the motor for a predetermined time, a function to extract specific frequency components of the current command value that are at or above a first frequency, amplify the specific frequency components and superimpose them on the current command value to generate an evaluation current, and a function to predict the failure time of the drive unit based on the time-series change trend of the evaluation current.

[0011] Furthermore, another robot diagnostic program disclosed herein enables a computer to perform a function to diagnose the state of a drive unit of a robot equipped with a motor. The robot diagnostic program enables a computer to perform a function to acquire a current command value for the motor for a predetermined time; a function to extract specific frequency components of the current command value that are above a first frequency, amplify the specific frequency components, and superimpose them on the frequency components of the current command value that are below the first frequency to generate an evaluation current; and a function to predict the failure time of the drive unit based on the time-series change trend of the evaluation current.

[0012] It should be noted that the aforementioned time series of evaluation currents does not refer to the state of the acquired current command values, but rather to a sequence of values ​​obtained by processing the evaluation currents generated from the current command values ​​at predetermined time intervals into, for example, effective values. [Effects of the Invention]

[0013] The above robot diagnostic device can accurately predict the remaining life of the driving part of the robot.

[0014] The above robot diagnostic method can accurately predict the remaining life of the driving part of the robot.

[0015] The above robot diagnostic program can accurately predict the remaining life of the driving part of the robot.

Brief Description of Drawings

[0016] [Figure 1] Figure 1 is a diagram showing the schematic configuration of a robot system. [Figure 2] Figure 2 is a block diagram showing the schematic configuration of a robot diagnostic device and its peripheral devices. [Figure 3] Figure 3 is a functional block diagram of the control unit of the robot diagnostic device. [Figure 4] Figure 4 is a flowchart showing the processing by the control unit of the robot diagnostic device. [Figure 5] Figure 5 is a diagram showing an example of the waveform of a current command value. [Figure 6] Figure 6 is a diagram showing an example of the waveform of a fundamental frequency component. [Figure 7] Figure 7 is a diagram showing an example of the waveform of a specific frequency component. [Figure 8] Figure 8 is a diagram showing an example of the waveform of an evaluation current. [Figure 9] Figure 9 is a diagram showing the effective value of the evaluation current plotted in time series on a display unit. [Figure 10] Figure 10 is a diagram showing an example of the waveform of a specific frequency component according to Modification 1. [Figure 11] Figure 11 is a diagram showing an example of the waveform of an evaluation current according to Modification 1. [Figure 12] Figure 12 is a diagram showing an example of the waveform of an evaluation current according to Modification 2. [Figure 13]FIG. 13 is a diagram showing an example of the waveform of the evaluation current according to Modification 3.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Hereinafter, exemplary embodiments will be described in detail based on the drawings. FIG. 1 is a diagram showing a schematic configuration of a robot system 100. FIG. 2 is a block diagram showing a schematic configuration of the robot diagnostic apparatus 1 and its peripheral devices.

[0018] The robot system 100 includes a robot diagnostic apparatus 1, a robot control apparatus 2, and a robot 3. In the robot system 100, the robot diagnostic apparatus 1 diagnoses the state of the drive unit 321 of the robot 3 and predicts the failure time of the drive unit 321. The robot diagnostic apparatus 1 predicts the failure time of the drive unit 321 based on the current command value for a predetermined time with respect to the motor 322 of the drive unit 321.

[0019] The robot 3 has a base 31 and a robot arm 32 rotatably connected to the base 31. The robot arm 32 is, for example, a vertically articulated arm. The robot arm 32 is mutual has a plurality of links rotatably connected thereto. Also Ta, Ro the robot arm 32 is provided with, for example, an end effector for gripping a workpiece. no E is provided.

[0020] The robot 3 has a drive unit 321 that drives each link of the robot arm 32. In the robot 3, each link forms an operating unit. The drive unit 321 has a motor 322 to which current is supplied and a speed reducer 323 that decelerates the rotational force of the motor 322 and transmits it to the operating unit. The motor 322 is, for example, a servo motor. The speed reducer 323 is, for example, a gear device in which a plurality of gears mesh with each other.

[0021] Robot 3 has a servo driver 311 that controls the supply current, which is the current supplied to motor 322. Specifically, the servo driver 311 is equipped with a current sensor 312 that measures the supply current. The servo driver 311 receives a current command value as input and supplies the motor 32 based on that input current command value. 2 Output to [this location].

[0022] The servo driver 311 provides feedback control of the supply current so that the actual rotational position of the motor 322, detected by an encoder (not shown), matches the target value. Specifically, the robot control device 2 often uses a control method in which it generates a current command value by multiplying the difference between the actual rotational position of the motor 322 and its target value, i.e., the position deviation, by a gain. The servo driver 311 also provides feedback of the measurement value from the current sensor 312, and if the measured current value is to be used as the evaluation target, it outputs the measured current value for evaluation to the robot control device 2. The measured value of the supply current is called the "measured current value". In this example, the servo driver 311 is provided on the base 31. The current sensor 312 may be provided outside or separately from the servo driver 311. For example, the servo driver 311 may be provided on the robot control device 2.

[0023] A supplementary explanation is provided regarding the motor 322 and servo driver 311. As mentioned above, a servo motor is generally used as the motor 322. There are two types of servo motors: conventional DC servo motors and AC servo motors, with AC servo motors also called brushless DC servo motors. The coils in an AC servo motor are composed of three phases: U-phase, V-phase, and W-phase. The servo driver 311 for the AC servo motor uses current command values ​​and commutation information, which is the angular relationship information between the motor coils and motor magnets, to create current command values ​​for each phase and control the three-phase coils. Two current sensors 312 are usually used to measure the current supplied to the three-phase coils. Since the measured current is an AC current, it is usually converted to an equivalent current value that is equivalent to the measured current value of a DC servo motor.

[0024] The robot control device 2 controls the robot 3. The robot control device 2 controls the various movements of each link and end effector of the robot 3. Specifically, the robot control device 2 controls the motor 32 2 The current command value is generated based on the rotation angle. The robot control device 2 causes the operating unit to perform the necessary operations during operation, while causing the operating unit to perform specific diagnostic operations (hereinafter also referred to as diagnostic operations) during diagnosis by the robot diagnostic device 1.

[0025] The robot control device 2 stores an operation program 21 in a memory unit (not shown). The operation program 21 is a diagnostic operation program that the robot control device 2 uses to perform diagnostic operations on the operating unit. The operation program 21 is read and executed by the computer of the robot control device 2. When the robot control device 2 is performing diagnostic operations on the operating unit, it outputs the current command value it has created to the robot diagnostic device 1. The period of outputting the current command value may be the same as or different from the control period of the robot 3. For example, the period of outputting the current command value may be several milliseconds.

[0026] The robot diagnostic device 1 predicts the timing of a failure in the drive unit 321 based on the current command value output from the robot control device 2. A failure in the drive unit 321 could be, for example, the motor 32 2 Examples of failures include those caused by wear or damage to the bearings, and those caused by wear or damage to the gears of the reducer 323. Specifically, the robot diagnostic device 1 comprises a storage unit 11, a display unit 12, and a control unit 13.

[0027] The storage unit 11 is a computer-readable storage medium that stores various programs and data. The storage unit 11 is formed from a magnetic disk such as a hard disk, an optical disk such as a CD-ROM or DVD, or a semiconductor memory.

[0028] Specifically, the memory unit 11 stores the diagnostic program 111. The diagnostic program 111 is an example of a robot diagnostic program. The diagnostic program 111 is a program that causes the computer, i.e., the control unit 13, to implement various functions for diagnosing the state of the drive unit 321 of the robot 3. The diagnostic program 111 is read and executed by the control unit 13.

[0029] The display unit 12 displays graphs and the like that show the effective value calculated by the control unit 13 and the predicted failure time. In this example, the display unit 12 displays a GUI (Graphical User Interface) screen, and displays graphs and the like on that GUI screen. The display unit 12 is, for example, a liquid crystal display or an organic EL display.

[0030] Figure 3 is a functional block diagram of the control unit 13 of the robot diagnostic device 1. The control unit 13 has various processors such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and / or a DSP (Digital Signal Processor), and various semiconductor memories such as RAM (Random Access Memory) and / or ROM (Read Only Memory). The control unit 13 reads and executes the diagnostic program 111, etc., from the storage unit 11.

[0031] Specifically, the control unit 13 has an acquisition unit 131, a generation unit 132, and a prediction unit 133 as functional blocks.

[0032] The acquisition unit 131 is motor 32 2The acquisition unit 131 acquires the current command value for a predetermined period of time. In other words, the acquisition unit 131 acquires the current command value output from the robot control device 2. The control unit 13 causes the robot control device 2 to perform a diagnostic operation on the operating part of the robot 3 for a predetermined period of time. The control unit 13 causes the operating part to perform a diagnostic operation, for example, once a day. The acquisition unit 131 acquires the current command value for the predetermined period of time and acquires these current command values ​​in chronological order (for example, daily). Alternatively, the diagnostic operation may be performed multiple times and the current command value for all of them may be acquired, or only the median value of the current command value within a certain period, such as one day, may be acquired. The certain period may be each working hour, such as day and night shifts or three-shift workdays, or it may be once every two days or once a week.

[0033] Furthermore, diagnostic operations are not limited to those performed for diagnostic purposes; necessary operations performed during operation may also be used. In this case, the necessary operations may be performed multiple times, and the current command values ​​may be obtained for all of them, or only the median value of the current command values ​​within a certain period, such as one day, may be obtained. The certain period may be each shift, such as day and night shifts or three-shift workdays, or it may be once every two days or once a week.

[0034] The generation unit 132 extracts specific frequency components of the current command value acquired by the acquisition unit 131 that are above the first frequency, amplifies these specific frequency components, and superimposes them on the frequency components of the current command value below the first frequency to generate an evaluation current. Hereinafter, the frequency components of the supply current below the first frequency will also be referred to as the "fundamental frequency components."

[0035] More specifically, the specific frequency component is the frequency component of the current command value between the first frequency and the second frequency. The generation unit 132 applies a low-pass filter with a passband of the first frequency and below to extract the fundamental frequency component from the current command value. The generation unit 132 also applies a band-pass filter with a passband of the first frequency and below the second frequency to extract the specific frequency component from the current command value. The generation unit 132 amplifies the extracted specific frequency component at a predetermined magnification and superimposes it on the fundamental frequency component to generate the evaluation current.

[0036] In this example, the generator 132 amplifies a specific frequency component by a factor of 10. The first frequency and the second frequency are set as the upper and lower limits of the range that includes vibration components originating from the deterioration of the drive unit 321, respectively. In this example, the first frequency is 11 Hz and the second frequency is 28 Hz.

[0037] The prediction unit 133 predicts the failure time of the drive unit 321 based on the time-series change trend of the evaluation current generated by the generation unit 132. More specifically, the prediction unit 133 predicts the failure time of the drive unit 321 based on the time-series change trend of the effective value calculated by the generation unit 132. More specifically, the prediction unit 133 predicts the failure time as the time when the effective value reaches a predetermined threshold, based on the time-series change trend of the effective value.

[0038] For example, the threshold value may be set to the effective value at the beginning of operation of the robot 3, or to a value of 107% to 110% after the robot 3 has been broken in. Alternatively, the threshold value may be set to 100% of the continuous stall current of the motor 322. The percentage values ​​mentioned above are just examples.

[0039] Furthermore, the generation unit 132 calculates the effective value of the evaluation current. The effective value is an example of an evaluation value used to evaluate the evaluation current.

[0040] Next, the diagnostic process of the robot diagnostic device 1 will be explained with reference to Figure 4. Figure 4 is a flowchart showing the process performed by the control unit 13 of the robot diagnostic device 1.

[0041] First, in step S1, the acquisition unit 131 acquires, for example, the current command value shown in Figure 5. Figure 5 is a graph showing an example of the waveform of the current command value. Note that for the sake of explanation, Figure 5 is a cropped portion corresponding to a certain time period. This is also the case for Figures 6 and beyond. Specifically, the control unit 13 causes the robot control device 2 to perform a diagnostic operation on the operating part of the robot 3, for example, once a day. At that time, the acquisition unit 131 acquires the current command value for a predetermined time period from the robot control device 2. The predetermined time period is, for example, several minutes.

[0042] In the subsequent step S2, as shown in Figure 6, the generation unit 132 extracts the fundamental frequency components of the current command value. Figure 6 shows an example of the waveform of the fundamental frequency components. For convenience, the vertical axis scale of Figure 6 has been reduced compared to Figures 5, 8, and 11-13. The same applies to Figures 7 and 10. In other words, from the current command value, frequency components below the first frequency, i.e., below 11 Hz, are extracted as the fundamental frequency components. As a result, only the low-frequency components of the current command value under normal conditions are extracted.

[0043] In the subsequent step S3, as shown in Figure 7, the generation unit 132 extracts specific frequency components of the current command value. Figure 7 shows an example of the waveform of specific frequency components. In other words, frequency components between the first frequency and the second frequency, i.e., between 11 Hz and 28 Hz, are extracted from the current command value. By setting the frequency to the first frequency and above, frequency components including vibration components originating from the deterioration of the drive unit 321 are extracted. By setting the frequency to the second frequency and below, high-frequency components such as noise are removed. Therefore, vibration components originating from the deterioration of the drive unit 321 are extracted, with as few high-frequency components such as noise as possible.

[0044] In the following step S4, the generation unit 132 amplifies specific frequency components. Although not shown in the diagram, the generation unit 132 amplifies specific frequency components by, for example, 10 times. This further emphasizes the vibration components originating from the deterioration of the drive unit 321.

[0045] In the subsequent step S5, as shown in Figure 8, the generation unit 132 superimposes the amplified specific frequency component onto the fundamental frequency component. In other words, the generation unit 132 generates an evaluation current by superimposing the specific frequency component amplified in step S4 onto the fundamental frequency component. Thus, the evaluation current consists of a fundamental frequency component, which is a low-frequency component consisting of the original current and an efficiency reduction component due to degradation that does not involve vibration, and a frequency component in which the vibration component originating from the degradation of the drive unit 321, which does not contain high-frequency components such as noise, is more emphasized. As a result, the waveform is such that the vibration component originating from the degradation of the drive unit 321 is appropriately emphasized compared to the original supply current.

[0046] In the subsequent step S6, the generation unit 132 calculates the effective value of the evaluation current. Generally, the effective value effectively reflects the fundamental frequency component, which is the inherent low-frequency component, and the efficiency reduction component due to degradation that is not accompanied by vibration, but it tends not to reflect components with relatively high frequencies. Since this effective value is calculated from a waveform in which the vibration component is appropriately emphasized, a result is obtained that more appropriately reflects the vibration component originating from the degradation of the drive unit 321.

[0047] In the following step S7, the prediction unit 133 predicts the timing of failure. Specifically, the prediction unit 133 predicts the timing of failure of the drive unit 321 based on the time-series trend of the evaluation current, more specifically, the time-series trend of the RMS value. More specifically, the prediction unit 133 predicts the timing when the RMS value reaches a predetermined threshold, based on the time-series trend of the RMS value, as the timing of failure. Thus, when step S7 is completed, the processing by the control unit 13, i.e., the diagnostic processing, is completed.

[0048] In this example, the prediction unit 133 can also display the prediction results on the display unit 12 according to the user's instructions. As shown in Figure 9, the prediction unit 133 plots the effective value of the evaluation current. Figure 9 is a graph showing the effective value of the evaluation current plotted in time series on the display unit 12. Specifically, the prediction unit 133 displays a graph showing the effective value of the evaluation current plotted in time series on the display unit 12. In Figure 9, the time-series plotted data of the effective value obtained from the current command value without any processing is indicated by a ◆ mark, and the time-series plotted data of the effective value obtained from the evaluation current is indicated by a ● mark.

[0049] As shown in Figure 9, the effective value of the evaluation current shows a more pronounced increasing trend than the effective value of the unprocessed current command, because it reflects the vibration component originating from degradation. Therefore, by predicting the failure time based on this trend in the effective value, it is possible to accurately predict the failure time.

[0050] Specifically, the prediction unit 133 draws a prediction line on the display unit 12 for the time-series plotted data in the reference interval A of the date. The prediction unit 133 draws the prediction line using the least squares method. The prediction unit 133 predicts the time when the prediction line intersects with a baseline line R that indicates a preset threshold as the failure time. As shown in Figure 9, in the reference interval A, the prediction line b drawn for the effective value of the evaluation current has a steeper slope, i.e., a greater gradient, than the prediction line a drawn for the effective value of the current command value that has not been processed. Therefore, the error in the intersection point between the prediction line and the baseline R, caused by, for example, a difference in the slope of the prediction line, is smaller for prediction line b than for prediction line a. Thus, by predicting the failure time based on the time-series change trend of the effective value of the evaluation current, the accuracy of the prediction is improved. In other words, the failure time of the drive unit 321 can be predicted with high accuracy. This allows maintenance to be performed at an appropriate time before the drive unit 321 fails.

[0051] Furthermore, if the reference interval for drawing the prediction line is set to, for example, reference interval B where the effective value of the evaluation current is gradually increasing, the slope of prediction line c in reference interval B will increase compared to prediction line b. In this case, it can be determined that the failure time is early. In this way, by displaying the prediction line and the reference line R on the display unit 12, the failure time can be visually determined. In addition, although not shown in this example, the failure time, i.e., the date when the prediction line intersects the reference line R, is also displayed on the display unit 12. In this example, the reference interval is set to a certain period from a date after the start date of operation of robot 3 to the present day. Empirically, this certain period is generally good to be around 10 to 30 days, but is not limited to this. Note that the certain period may be from the start date of operation of robot 3 to the present day.

[0052] As described above, the robot diagnostic device 1 is a device for diagnosing the state of the drive unit 321 of a robot 3 that includes a motor 322. The robot diagnostic device 1 includes an acquisition unit 131 that acquires current command values ​​for the motor 322 for a predetermined time, a generation unit 132 that extracts fundamental frequency components below a first frequency and specific frequency components above the first frequency from the current command values ​​acquired by the acquisition unit 131, amplifies the specific frequency components and superimposes them on the fundamental frequency components to generate an evaluation current, and a prediction unit 133 that predicts the failure time when the drive unit 321 will fail based on the time-series change trend of the evaluation current generated by the generation unit 132.

[0053] Furthermore, the robot diagnostic method is a method for diagnosing the state of the drive unit 321 of a robot 3 equipped with a motor 322. This method includes obtaining a current command value for the motor 322 for a predetermined time, extracting fundamental frequency components of the current command value below a first frequency and specific frequency components above the first frequency, amplifying the specific frequency components and superimposing them on the fundamental frequency components to generate an evaluation current, and predicting the failure time at which the drive unit 321 will fail based on the time-series change trend of the evaluation current.

[0054] Furthermore, the diagnostic program 111 is a program that enables the computer to perform a function to diagnose the state of the drive unit 321 of the robot 3, which includes a motor 322. The diagnostic program 111 enables the computer to perform the following functions: to acquire a current command value for the motor 322 for a predetermined time; to extract fundamental frequency components below a first frequency and specific frequency components above the first frequency of the current command value, amplify the specific frequency components and superimpose them on the fundamental frequency components to generate an evaluation current; and to predict the failure time of the drive unit 321 based on the time-series change trend of the evaluation current.

[0055] With these configurations, fundamental frequency components below the first frequency are extracted, resulting in the extraction of only the low-frequency components of the current command value. These low-frequency components include the inherent components under normal conditions and efficiency reduction components due to degradation without vibration. By extracting specific frequency components above the first frequency, frequency components including vibration components originating from the degradation of the drive unit 321 are extracted. By amplifying the specific frequency components, the vibration components originating from the degradation of the drive unit 321 are further emphasized. When processing such as RMS values ​​is performed, low-frequency components are effectively reflected, but higher frequency components tend not to be reflected as well. An evaluation current is generated in which the fundamental frequency components of the low-frequency components of the inherent current command value are superimposed with frequency components in which the vibration components originating from the degradation of the drive unit 321 are further emphasized. Therefore, a waveform in which the vibration components originating from the degradation of the drive unit 321 are appropriately emphasized can be obtained compared to the original current command value. By predicting the failure timing of the drive unit 321 based on this trend of change in evaluation current, an appropriate prediction can be made. Thus, the remaining lifespan of the drive unit 321 of the robot 3 can be predicted with high accuracy.

[0056] Furthermore, specific frequency components are frequency components of the current command value that are between the first and second frequencies.

[0057] With this configuration, high-frequency components such as noise are removed by setting the frequency to the second frequency or lower. Therefore, it is possible to extract vibration components originating from the deterioration of the drive unit 321, which contain as few such high-frequency components as possible. As a result, it is possible to generate an evaluation current in which the vibration components originating from the deterioration of the drive unit 321 are appropriately emphasized. This makes it possible to predict the failure time, i.e., the remaining lifespan, of the drive unit 321 of the robot 3 with greater accuracy.

[0058] Furthermore, in the robot diagnostic device 1, the generation unit 132 calculates the effective value of the evaluation current, and the prediction unit 133 predicts the timing of failure based on the time-series change trend of the effective value calculated by the generation unit 132.

[0059] With this configuration, the failure timing is predicted based on the trend of change in the effective value of the evaluation current, meaning the prediction is based on the trend of change in the average value of the evaluation current. Therefore, phenomena such as the gradual deterioration of the drive unit 321 can be appropriately and stably detected.

[0060] 《Example 1》 This modified example 1 is a modification of the above embodiment in which the generation of the evaluation current by the generation unit 132 is changed. In other words, the generation unit 132 in this example extracts frequency components of the current command value that are at or above the first frequency as specific frequency components.

[0061] Specifically, the generation unit 132 applies a low-pass filter with a passband of frequencies below the first frequency to extract the fundamental frequency component from the current command value. The generation unit 132 also applies a high-pass filter with a passband of frequencies above the first frequency to extract specific frequency components from the current command value. The generation unit 132 amplifies the extracted specific frequency components, for example, by 10 times, and superimposes them on the fundamental frequency component to generate the evaluation current.

[0062] In this modified example, only step S3 differs from the above embodiment in the flowchart of Figure 4. That is, in step S3, as shown in Figure 10, the generation unit 132 extracts specific frequency components of the current command value. Figure 10 is a diagram showing an example of the waveform of specific frequency components according to Modified Example 1. In other words, frequency components of the current command value that are above the first frequency, i.e., 11 Hz or higher, are extracted. By setting the frequency to above the first frequency, frequency components including vibration components originating from the deterioration of the drive unit 321 are extracted. Therefore, vibration components originating from the deterioration of the drive unit 321 are extracted. The generation unit 132 superimposes the amplified specific frequency components onto the fundamental frequency components.

[0063] In step S5, as shown in Figure 11, the generation unit 132 generates an evaluation current in which amplified specific frequency components are superimposed on the fundamental frequency components. Figure 11 is a diagram showing an example of the waveform of the evaluation current according to Modification 1. In this way, the evaluation current is formed by superimposing a frequency component in which the frequency component originating from the deterioration of the drive unit 321 is more emphasized onto the fundamental frequency component of the low-frequency component of the original current command value. As a result, the waveform is such that the vibration component originating from the deterioration of the drive unit 321 is emphasized compared to the original current command value. Therefore, even in this Modification 1, the failure time of the drive unit 321, i.e., the remaining lifespan, can be accurately predicted by predicting the failure time based on the change trend of the evaluation current which reflects the vibration component originating from the deterioration of the drive unit 321. The other configurations, operations, and effects are the same as in the above embodiment.

[0064] 《Modified Example 2》 This modified example 2 is a modification of the above embodiment in which the generation of the evaluation current by the generation unit 132 is changed. In other words, the generation unit 132 in this example generates an evaluation current in which a specific frequency component is superimposed on the original current command value.

[0065] Specifically, the generation unit 132 applies a bandpass filter with a passband between the first frequency and the second frequency to extract specific frequency components from the current command value. The generation unit 132 amplifies the extracted specific frequency components, for example, by 10 times, and superimposes them onto the original current command value to generate the evaluation current.

[0066] In this modified example, step S2 is omitted in the flowchart of Figure 4, and step S5 differs from that of the previous embodiment. Specifically, in step S5, as shown in Figure 12, the generation unit 132 generates an evaluation current by superimposing an amplified specific frequency component onto the current command value. Figure 12 shows an example of the waveform of the evaluation current according to Modified Example 2. In this way, the evaluation current is formed by superimposing a frequency component that is more emphasized than the fundamental frequency component of the low-frequency component of the original current command value, which does not contain an abnormally high high-frequency component, thus resulting in a waveform in which the vibration component originating from the deterioration of the drive unit 321 is appropriately emphasized compared to the original current command value. Therefore, even in this Modified Example 2, the failure timing can be predicted with high accuracy. Other configurations, operations, and effects are the same as in the previous embodiment.

[0067] Variation 3 This third variation is a modification of the generation of the evaluation current by the generation unit 132 in the second variation. In other words, the generation unit 132 in this example extracts frequency components of the current command value that are above the first frequency as specific frequency components.

[0068] Specifically, the generation unit 132 extracts specific frequency components of a first frequency or higher from the current command value. The generation unit 132 amplifies the extracted specific frequency components, for example, by 10 times, and superimposes them onto the current command value to generate the evaluation current.

[0069] In this modified example, step S2 is omitted in the flowchart of Figure 4, and steps S3 and S5 differ from those of the above embodiment. Specifically, in step S3, the generation unit 132 extracts specific frequency components of the current command value that are at or above the first frequency. In step S5, as shown in Figure 13, the generation unit 132 generates an evaluation current by superimposing the amplified specific frequency components onto the current command value. Figure 13 is a diagram showing an example of the waveform of the evaluation current according to Modified Example 3. In this way, the evaluation current is formed by superimposing frequency components that are more emphasized than the frequency components originating from the deterioration of the drive unit 321 onto the original current command value, resulting in a waveform in which the vibration components originating from the deterioration of the drive unit 321 are emphasized compared to the original current command value. Therefore, even in this Modified Example 3, the failure timing can be predicted with high accuracy. Other configurations, operations, and effects are the same as in the above embodiment.

[0070] Other embodiments As described above, the embodiments described herein have been presented as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted as appropriate. Furthermore, it is possible to combine the components described in the embodiments above to create new embodiments. In addition, the components described in the attached drawings and detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the technology. Therefore, the mere presence of such non-essential components in the attached drawings and detailed description should not be immediately assumed to mean that those non-essential components are essential.

[0071] For example, if motor 322 is a DC servo motor, the measured current value may be used as the current command value, and if motor 322 is an AC servo motor, the measured equivalent current value may be used as the current command value. The current command value, the measured current value, and the measured equivalent current value are all substantially the same because they are all controlled by current within the servo driver 311. Alternatively, the torque command value may be used as the current command value. The torque command value is obtained by multiplying the current command value by a torque constant, and is therefore synonymous with the current command value. Furthermore, as mentioned above, the current command value is generated by multiplying the position deviation by a gain, so the position deviation may be used as the current command value. Thus, in the technology disclosed herein, the current command value is a concept that includes the measured current value, the measured equivalent current value, the torque command value, and the position deviation. Values ​​referred to as current feedback value, current monitor value, and torque monitor value are also variations and name changes related to the state and application, and can be used similarly.

[0072] Furthermore, the acquisition unit 131 of the robot diagnostic device 1 may acquire a temperature-compensated current command value as the current command value.

[0073] Furthermore, the robot diagnostic device 1 may be configured using a general-purpose personal computer. Also, a display unit 12 may be a display device such as an LCD screen of a personal computer.

[0074] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, then the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor. [Explanation of Symbols]

[0075] 1. Robotic diagnostic device 3 Robots 111 Diagnostic Program (Robot Diagnostic Program) 131 Acquisition Department 132 Generation part 133 Prediction Section 321 Drive Unit 322 Motor

Claims

1. A robot diagnostic device for diagnosing the condition of a drive unit, which includes a motor, of a robot equipped with a drive unit, An acquisition unit that acquires current command-related values, such as the current command value, measured current value, torque command value, or position deviation, for the motor over a predetermined period of time. A generation unit extracts specific frequency components of the current command-related value acquired by the acquisition unit, which have a first frequency or higher, amplifies the specific frequency components, and generates an evaluation current superimposed on the current command-related value; A robot diagnostic device comprising: a prediction unit that predicts the timing of failure of the drive unit based on the time-series change trend of the evaluation current generated by the generation unit.

2. A robot diagnostic device for diagnosing the condition of a drive unit, which includes a motor, of a robot equipped with a drive unit, An acquisition unit that acquires current command-related values, such as the current command value, measured current value, torque command value, or position deviation, for the motor over a predetermined period of time. A generation unit extracts specific frequency components of the current command-related value acquired by the acquisition unit that are at or above the first frequency, amplifies the specific frequency components, and generates an evaluation current that is superimposed on the frequency components of the current command-related value that are at or below the first frequency; A robot diagnostic device comprising: a prediction unit that predicts the timing of failure of the drive unit based on the time-series change trend of the evaluation current generated by the generation unit.

3. In the robot diagnostic device according to claim 1 or 2, The robot diagnostic device wherein the specified frequency component is a frequency component of the current command-related value between the first frequency and the second frequency.

4. In the robot diagnostic device according to any one of claims 1 to 3, The generation unit calculates the effective value of the evaluation current, The prediction unit is a robot diagnostic device that predicts the timing of failure based on the time-series change trend of the effective value calculated by the generation unit.

5. In the robot diagnostic device according to claim 4, The prediction unit is a robot diagnostic device that predicts the timing of failure based on the time-series change trend of the effective value over a certain period from a date after the robot's start date to the present day.

6. In the robot diagnostic device according to claim 4 or 5, The prediction unit is a robot diagnostic device that predicts the time when the effective value reaches a predetermined threshold, based on the time-series trend of the effective value, as the time of failure.

7. A robot diagnostic method for diagnosing the state of a drive unit, which includes a motor, of a robot equipped with a drive unit, To acquire current command-related values, such as the current command value, measured current value, torque command value, or position deviation, for the motor over a predetermined period of time. The process involves extracting specific frequency components of the current command-related value with a frequency of 1 or higher, amplifying these specific frequency components, and superimposing them onto the current command-related value to generate an evaluation current. A robot diagnostic method that includes predicting the timing of failure of the drive unit based on the time-series change trend of the evaluation current.

8. A robot diagnostic method for diagnosing the state of a drive unit, which includes a motor, of a robot equipped with a drive unit, To acquire current command-related values, such as the current command value, measured current value, torque command value, or position deviation, for the motor over a predetermined period of time. The process involves extracting specific frequency components of the current command-related value that are at or above the first frequency, amplifying these specific frequency components, and superimposing them on the frequency components of the current command-related value that are at or below the first frequency to generate an evaluation current. A robot diagnostic method that includes predicting the timing of failure of the drive unit based on the time-series change trend of the evaluation current.

9. A robot diagnostic program that enables a computer to perform a function to diagnose the state of a drive unit, including a motor, of a robot equipped with such a drive unit, A function to acquire current command-related values, such as the current command value, measured current value, torque command value, or position deviation, for the motor over a predetermined period of time. A function to extract specific frequency components of the current command-related value with a frequency of 1 or higher, amplify the specific frequency components, and generate an evaluation current by superimposing them on the current command-related value, A robot diagnostic program that enables a computer to perform a function to predict the timing of failure of the drive unit based on the time-series trend of the evaluation current.

10. A robot diagnostic program that enables a computer to perform a function to diagnose the state of a drive unit, including a motor, of a robot equipped with such a drive unit, A function to acquire current command-related values, such as the current command value, measured current value, torque command value, or position deviation, for the motor over a predetermined period of time. A function to extract specific frequency components of the current command-related value with a frequency of 1 or higher, amplify the specific frequency components, and generate an evaluation current by superimposing them on the frequency components of the current command-related value with a frequency of 1 or lower, A robot diagnostic program that enables a computer to perform a function to predict the timing of failure of the drive unit based on the time-series trend of the evaluation current.

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