Adjustment support device

Abstract

Provided is a technique capable of maintaining a stability margin before adjustment of the gain filter of a motor control device even after adjustment. An adjustment support device 20 comprises: a frequency characteristic measurement unit 300 for measuring the frequency characteristics of a motor control device 1; a frequency characteristic acquisition unit 21 for acquiring frequency characteristics before adjustment from the frequency characteristic measurement unit 300; a stability margin reading unit 22 for reading a stability margin from the frequency characteristics acquired by the frequency characteristic acquisition unit 21; a stability margin setting unit 23 for setting the stability margin read by the stability margin reading unit 22 as a target margin for adjustment; and an adjustment unit 400 for adjusting a gain and a filter coefficient on the basis of the target margin.

Description

Adjustment support device

[0001] The present disclosure relates to an adjustment assistance device.

[0002] Conventionally, techniques for automatically adjusting gain in motor control devices have been known, and examples of such techniques include Japanese Patent Application Laid-Open No. 2003-124999 and Japanese Patent Application Laid-Open No. 2003-124999.

[0003] JP 2009-165258 A JP 2016-092935 A

[0004] When automatically adjusting the gain filter of a machine tool motor, it is sometimes desirable to compare the characteristic changes and stability margins before and after the adjustment. However, in conventional automatic adjustment, the target margin for adjustment is specified independently of the stability margin before the adjustment, which results in a change in the stability margin before and after the adjustment, making it difficult to compare the characteristic changes.

[0005] The present disclosure has been made in view of the above-mentioned problems, and aims to provide a technique that can maintain the stability margin before adjustment of the gain filter of a motor control device even after adjustment.

[0006] The present disclosure relates to an adjustment support device that adjusts at least one filter coefficient and gain of a motor control device that controls the rotation of a motor, the adjustment support device comprising: a frequency characteristic measurement unit that measures frequency characteristics of the motor control device; a frequency characteristic acquisition unit that acquires the frequency characteristics before adjustment from the frequency characteristic measurement unit; a stability margin reading unit that reads a stability margin from the frequency characteristics acquired by the frequency characteristic acquisition unit; a stability margin setting unit that sets the stability margin read by the stability margin reading unit as a target margin for adjustment; and an adjustment unit that adjusts the gain and the filter coefficient based on the target margin.

[0007] According to the present disclosure, it is possible to provide a technique that can maintain the stability margin before adjustment of the gain filter of a motor control device even after adjustment.

[0008] FIG. 1 is a functional block diagram of a motor control device to which an adjustment support device according to a first embodiment is applied. FIG. 2 is a Bode plot diagram showing frequency characteristics before adjustment acquired by a frequency characteristic acquisition unit. FIG. 3 is a Bode plot diagram showing frequency characteristics before and after adjustment by an adjustment unit. FIG. 4 is a flowchart showing an example of the flow of adjustment processing by the adjustment support device according to the first embodiment. FIG. 5 is a Nyquist plot diagram showing an example of a stability margin read from the frequency characteristics. FIG. 6 is a Bode plot diagram showing an example of a stability margin read from the frequency characteristics. FIG. 7 is a functional block diagram of a motor control device to which an adjustment support device according to a second embodiment is applied. FIG. 8 is a flowchart showing an example of the flow of adjustment processing by the adjustment support device according to the second embodiment.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0010] First, a description will be given of the overall configuration of a motor control device 1 to which an adjustment assist device 20 is applied. Fig. 1 is a functional block diagram of a motor control device 1 to which an adjustment assist device 20 according to a first embodiment is applied.

[0011] The controlled object of the motor control device 1 is, for example, a machine tool, a robot, or an industrial machine. The motor control device 1 may be provided as a part of the controlled object such as a machine tool, a robot, or an industrial machine.

[0012] The motor control device 1 is configured using, for example, a computer including memories such as ROM (read only memory) and RAM (random access memory), a CPU (central processing unit), and a communication control unit, all connected via a bus. The functions and operations of each functional unit of the motor control device 1, which will be described below, are achieved by the cooperation of the CPU and memory installed in the computer and the control program stored in the memory. Note that the motor control device 1 may also be configured to control the above-mentioned controlled object based on information input from an external computer.

[0013] The motor control device 1 includes a motor control unit 10 and an adjustment support device 20. In the configuration shown in Figure 1, the adjustment support device 20 is located inside the motor control device 1, but the location of the adjustment support device 20 is not particularly limited, and the adjustment support device 20 may be located outside the motor control device 1.

[0014] The motor control unit 10 constitutes a servo system of a closed speed feedback loop together with the motor 150. As shown in Fig. 1, the motor control unit 10 includes a subtractor 110, a speed control unit 120, a filter 130, and a current control unit 140 as functional units executed on a processor.

[0015] The subtractor 110 calculates the difference between the input speed command and the detected speed that has been fed back, and outputs this difference as a speed deviation to the speed control unit 120. In this embodiment, the speed command input to the subtractor 110 is input from the frequency generation unit 200. The frequency generation unit 200 outputs a sine wave signal as the speed command while changing the frequency. The frequency generation unit 200 may be disposed in the above-mentioned controlled object, or may be disposed in the motor control device 1 (motor control unit 10).

[0016] The speed control unit 120 adds together the value obtained by multiplying the speed deviation by integral gain K1v and integrating the result, and the value obtained by multiplying the speed deviation by proportional gain K2v, and outputs the result as a torque command to the filter 130. The speed control unit 120 is a control unit that sets the feedback gain.

[0017] The filter 130 is a filter that attenuates specific frequency components, and may be, for example, a notch filter, a low-pass filter, or a band-stop filter. The above-described controlled object having a mechanical part driven by the motor 150 has a resonance point, and resonance may increase in the motor control unit 10. A filter such as a notch filter can reduce the resonance. The output of the filter 130 is output to the current control unit 140 as a torque command.

[0018] The following Equation 1 shows the transfer function F(s) of the notch filter serving as the filter 130. The parameters are coefficients δ, τ, and ωc. In Equation 1, the coefficient δ is the attenuation coefficient, the coefficient τ is the fractional bandwidth, and the coefficient ωc is the central angular frequency. If the central frequency is fc and the bandwidth is fw, the coefficient ωc is expressed as ωc = 2πfc, and the coefficient τ is expressed as τ = fw / fc.

[0019]

[0020] Current control unit 140 generates a current command for driving motor 150 based on the torque command and outputs the current command to motor 150. If motor 150 is a linear motor, the position of the movable part is detected by a linear scale (not shown) provided in motor 150, and a speed detection value is obtained by differentiating the position detection value, and the obtained speed detection value is input to subtractor 110 as speed feedback. If motor 150 is a motor having a rotating shaft, the rotation angle position is detected by a rotary encoder (not shown) provided in motor 150, and the speed detection value is input to subtractor 110 as speed feedback.

[0021] Next, a description will be given of the adjustment assisting device 20. The adjustment assisting device 20 adjusts at least one filter coefficient and feedback gain of the motor control device 1 that controls the rotation of the motor 150.

[0022] The adjustment support device 20 includes a frequency characteristic acquisition unit 21, a stability margin reading unit 22, a stability margin setting unit 23, a frequency characteristic measurement unit 300, and an adjustment unit 400 as functional units executed on a processor.

[0023] The frequency generating unit 200 outputs a sinusoidal signal as a speed command while changing the frequency to the subtractor 110 of the motor control unit 10 and the frequency characteristic measuring unit 300 of the adjustment support device 20 .

[0024] The frequency characteristic measuring unit 300 measures the frequency characteristic of the motor control device 1 and outputs the measured frequency characteristic to the frequency characteristic acquiring unit 21 and the adjusting unit 400 .

[0025] 2 is a Bode diagram showing the frequency characteristics before adjustment acquired by the frequency characteristic acquisition unit 21. The frequency characteristic measurement unit 300 uses the speed command (sine wave) generated by the frequency generation unit 200 as an input signal, and the detected speed (sine wave) as an output signal output from a rotary encoder (not shown) or the differential of the detected position (sine wave) as an output signal output from a linear scale to measure the amplitude ratio (input / output gain) between the input signal and the output signal and the phase delay as frequency characteristics for each frequency specified by the speed command. The frequency characteristic acquisition unit 21 acquires the frequency characteristics measured by the frequency characteristic measurement unit 300 as described above.

[0026] The stability margin reading unit 22 reads and acquires the stability margin from the frequency characteristics acquired by the frequency characteristics acquiring unit 21. The stability margin reading unit 22 selects, as the stability margin, for example, from a gain margin, a phase margin, a sensitivity peak value, a maximum value of the closed-loop characteristics, or a combination thereof.

[0027] An example in which the stability margin reading unit 22 reads the gain margin as the stability margin will be described. The gain margin is read based on the gain when the phase delay is 180 degrees in the open loop characteristics. As shown in FIG. 2, the stability margin reading unit 22 measures the difference between the loop gain when the phase delay is 180 degrees and 0 dB as the gain margin. The method for measuring the gain margin is not limited to the method using a Bode diagram. For example, the gain margin may be measured using calculations or a Nyquist diagram.

[0028] The stability margin setting unit 23 sets the stability margin read by the stability margin reading unit 22 as a target margin when the adjustment unit 400 adjusts the gain filter. In this example, the gain margin is set to the target margin.

[0029] The adjustment unit 400 optimizes the gain and the filter based on the target margin set by the stability margin setting unit 23. The adjustment unit 400 adjusts the gain filter using, for example, a learning model constructed by machine learning. However, the method of adjusting the gain filter by the adjustment unit 400 is not limited to machine learning.

[0030] The learning model is constructed by machine learning that is performed in advance. In the following description, a case where the learning model of the adjustment unit 400 is constructed by reinforcement learning will be described, but the present invention is not limited to reinforcement learning, and can also be applied to a case where the learning model is constructed by supervised learning, for example.

[0031] In reinforcement learning, Q-learning can be used, which is a method of learning a value function Q(S, A) that selects an action A under a certain environmental state S. The objective of Q-learning is to select the action A with the highest value function Q(S, A) as the optimal action from among the possible actions A when the state S is certain.

[0032] A well-known technology called DQN (Deep Q-Network) may be used. When using DQN, the value function Q may be configured using an appropriate neural network, and the value of the value function Q(S, A) may be calculated by approximating the value function Q with the appropriate neural network by adjusting the parameters of the neural network. By using DQN, it is possible to shorten the time required for Q-learning to converge.

[0033] The learning model defines a state S as the integral gain K1v and proportional gain K2v of the speed control unit 120, the values ​​of the coefficients ωc, τ, and δ of the transfer function of the filter 130, and the input / output gain (amplitude ratio) and phase delay output from the frequency characteristic measurement unit 300, and learns a value function Q that selects, as action A, adjustment of the integral gain K1v and proportional gain K2v of the speed control unit 120 and the values ​​of the coefficients ωc, τ, and δ of the transfer function of the filter 130, which relate to the state S. This enables the learning model to select the optimal action A (i.e., the integral gain K1v and proportional gain K2v of the speed control unit 120, and the optimal coefficients ωc, τ, and δ of the transfer function of the filter 130).

[0034] Based on the learned value function Q, the adjustment unit 400 selects, from among the actions A that are applied to the integral gain K1v and proportional gain K2v of the speed control unit 120 for a certain state S, and the coefficients ωc, τ, and δ of the transfer function of the filter 130, the action A that maximizes the value of Q.

[0035] Then, the adjustment unit 400 selects action A that maximizes the value of Q, thereby selecting action A (i.e., the integral gain K1v and proportional gain K2v of the speed control unit 120, and / or the coefficients ωc, τ, and δ of the transfer function of the filter 130) such that the stability margin of the motor control unit 10 generated by executing a program that generates a sinusoidal signal with a changing frequency is equal to or greater than the value of the target gain margin set by the stability margin setting unit 23.

[0036] 3 is a Bode plot showing frequency characteristics before and after adjustment by adjustment unit 400. As shown in FIG. 3, adjustment by adjustment unit 400 optimizes filter 130 and improves phase lag. The gain is then improved until the stability margin reaches a target gain margin that is the same as the stability margin before adjustment. Therefore, the stability margin before adjustment is maintained even after adjustment.

[0037] Next, the overall processing flow by the adjustment support device 20 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of the flow of adjustment processing by the adjustment support device 20 according to the first embodiment.

[0038] In step S10 , the frequency characteristic measuring unit 300 measures the frequency characteristic of the motor control device 1 .

[0039] In step S11 , the frequency characteristic acquisition unit 21 acquires the frequency characteristic from the frequency characteristic measurement unit 300 .

[0040] In step S12, the stability margin reading unit 22 analyzes the frequency characteristics acquired by the frequency characteristic acquiring unit 21, and reads stability margins such as gain margins.

[0041] In step S13 , the stability margin setting unit 23 sets a target margin (target gain margin) for the adjustment unit 400 based on the stability margin read by the stability margin reading unit 22 .

[0042] In step S14, the adjustment unit 400 adjusts the integral gain K1v and proportional gain K2v of the speed control unit 120 and the coefficients ωc, τ, and δ of the transfer function of the filter 130 so that the stability margin becomes the target margin. This completes the adjustment.

[0043] Although an example has been described in which the gain margin is obtained as the stability margin from the Bode diagram, the stability margin is not limited to the gain margin.

[0044] 5 is a Nyquist diagram that schematically illustrates an example of a stability margin that can be read from frequency characteristics. As shown in FIG. 5, the gain margin, phase margin, and peak sensitivity value may be obtained as stability margins from the Nyquist diagram that illustrates frequency characteristics. The gain margin Gm can be obtained using the following Equation 2. The phase margin can be obtained from the angle PM in FIG. 5, and the peak sensitivity value can be obtained from 1 / η.

[0045]

[0046] 6 is a Bode diagram showing an example of a stability margin read from frequency characteristics. As shown in FIG. 6, the maximum value Mp of the closed loop characteristics can be obtained from the Bode diagram showing frequency characteristics.

[0047] As described above, the adjustment support device 20 of this embodiment includes a frequency characteristic measurement unit 300 that measures the frequency characteristics of the motor control device 1, a frequency characteristic acquisition unit 21 that acquires the frequency characteristics before adjustment from the frequency characteristic measurement unit 300, a stability margin reading unit 22 that reads a stability margin from the frequency characteristics acquired by the frequency characteristic acquisition unit 21, a stability margin setting unit 23 that sets the stability margin read by the stability margin reading unit 22 as a target margin for adjustment, and an adjustment unit 400 that adjusts the gain and filter coefficient based on the target margin.

[0048] As a result, the gain and filter coefficients are adjusted with the pre-adjustment stability margin as the target margin, so that the pre-adjustment stability margin of the gain and filter of the motor control device 1 can be maintained even after adjustment.

[0049] In this embodiment, at least one of the gain margin, the phase margin, the peak sensitivity value, and the maximum value of the closed loop characteristic is selected as the stability margin.

[0050] This allows the stability margin to be maintained by adjustment to be selected from the gain margin, phase margin, sensitivity peak value, and maximum value of the closed loop characteristics, and allows an appropriate stability margin to be set according to the situation and the user's wishes.

[0051] Next, a description will be given of the configuration of the second embodiment, which differs from the first embodiment. Note that the same reference numerals will be used to designate the same or similar configurations as those in the above embodiments, and detailed description thereof will be omitted.

[0052] 7 is a functional block diagram of a motor control device 1a to which an adjustment support device 20a according to the second embodiment is applied. As shown in FIG. 7, the adjustment support device 20a according to the second embodiment further includes a second frequency characteristic acquisition unit 25, a second stability margin reading unit 26, and a screen display unit 50 in addition to the configuration according to the first embodiment.

[0053] The adjustment support device 20a of the second embodiment can display information including the frequency characteristics and stability margins before and after adjustment on a screen display unit 50 configured with a display or the like, and present the adjustment results to the user. The screen display unit 50 may be configured integrally with the motor control device 1a or may be configured separately.

[0054] Each component of the adjustment support device 20a according to the second embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart showing an example of the flow of adjustment processing by the adjustment support device 20a according to the second embodiment.

[0055] In step S20, the frequency characteristic measuring unit 300 measures the frequency characteristic of the motor control device 1a before adjustment.

[0056] In step S21, the frequency characteristic acquisition unit 21 acquires the frequency characteristic before adjustment from the frequency characteristic measurement unit 300.

[0057] In step S22, the stability margin reading unit 22 analyzes the frequency characteristics acquired by the frequency characteristic acquiring unit 21, and reads the stability margin before adjustment.

[0058] In step S23 , the stability margin setting unit 23 sets a target margin for the adjustment unit 400 based on the pre-adjustment stability margin read by the stability margin reading unit 22 .

[0059] In step S24, the adjustment unit 400 adjusts the integral gain K1v and proportional gain K2v of the speed control unit 120, and the coefficients ωc, τ, and δ of the transfer function of the filter 130, so that the stability margin becomes the target margin. This completes the adjustment.

[0060] In step S25 , the second frequency characteristic acquisition unit 25 measures the frequency characteristics after adjustment by the adjustment unit 400 .

[0061] In step S26 , the second stability margin reading unit 26 obtains the adjusted stability margin from the frequency characteristics obtained by the second frequency characteristics obtaining unit 25 .

[0062] In step S27, the screen display unit 50 displays a comparison screen showing information including the frequency characteristics and stability margins before and after the adjustment.

[0063] As described above, the adjustment support device 20a of the second embodiment further includes a second frequency characteristic acquisition unit 25 that acquires the frequency characteristic after adjustment by the adjustment unit 400, a second stability margin reading unit 26 that acquires the stability margin from the frequency characteristic acquired by the second frequency characteristic acquisition unit 25, and a screen display unit 50 that displays information including the frequency characteristic and stability margin before and after the adjustment.

[0064] This allows the frequency characteristics and stability margins before and after adjustment to be displayed on the screen display unit 50, allowing the user to easily check the adjustment results.

[0065] In the above embodiment, the gain of the speed control unit 120 is described as the adjustment target of the adjustment unit 400, but other gains such as the gain of the current control unit 140 may also be adjusted. Furthermore, the adjustment method of the adjustment unit 400 is not limited to reinforcement learning, and supervised learning may be used, or adjustment may be performed using a predetermined algorithm different from machine learning.

[0066] The above-described series of processes can be executed by hardware or software. In other words, the above-described functional configuration is merely exemplary and is not particularly limited. That is, it is sufficient for a computer to have the functionality to execute the above-described series of processes as a whole, and the functional blocks used to realize these functions are not particularly limited to the above-described example. Furthermore, the locations of the functional blocks are also not particularly limited and may be arbitrary. For example, one functional block may be configured as a single piece of hardware, a single piece of software, or a combination thereof. When the series of processes are executed by software, the program that constitutes the software is installed into a computer or the like from a network or a recording medium. The computer may be a computer built into dedicated hardware. Furthermore, the computer may be a computer capable of executing various functions by installing various programs, such as a server, a general-purpose smartphone, or a personal computer.

[0067] A recording medium containing such a program may be constituted not only by a removable medium (not shown) that is distributed separately from the device main body in order to provide the program to users, but also by a recording medium that is provided to users in a state where it is pre-installed in the device main body. Since the program can be distributed via a network, the recording medium may be installed in or accessible from a computer that is connected to or connectable to the network. Furthermore, the steps that describe the program recorded on the recording medium include not only processes that are performed chronologically in accordance with the order in which they are written, but also processes that are not necessarily processed chronologically but are executed in parallel or individually.

[0068] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0069] The following supplementary note is further disclosed regarding the above embodiment and modified examples. (Supplementary Note 1) An adjustment support device (20, 20a) that adjusts at least one filter coefficient and gain of a motor control device (1, 1a) that controls the rotation of a motor, comprising: a frequency characteristic measurement unit (300) that measures frequency characteristics of the motor control device, a frequency characteristic acquisition unit (21) that acquires pre-adjustment frequency characteristics from the frequency characteristic measurement unit, a stability margin reading unit (22) that reads a stability margin from the frequency characteristic acquired by the frequency characteristic acquisition unit, a stability margin setting unit (23) that sets the stability margin read by the stability margin reading unit as a target margin for adjustment, and an adjustment unit (400) that adjusts the gain and the filter coefficient based on the target margin.

[0070] (Supplementary Note 2) The above adjustment support device (20a) further includes: a second frequency characteristic acquisition unit (25) that acquires, from the frequency characteristic measurement unit, the frequency characteristic of the motor control device after adjustment by the adjustment unit; a second stability margin reading unit (26) that reads a stability margin from the frequency characteristic acquired by the second frequency characteristic acquisition unit; and a screen display unit (50) that displays information including the frequency characteristic and the stability margin before and after adjustment.

[0071] (Supplementary Note 3) In the above adjustment support device (20, 20a), the stability margin includes at least one of a gain margin, a phase margin, a sensitivity peak value, and a maximum value of a closed-loop characteristic.

[0072] REFERENCE SIGNS LIST 1, 1a Motor control device 20, 20a Adjustment support device 21 Frequency characteristic acquisition unit 22 Stability margin reading unit 23 Stability margin setting unit 25 Second frequency characteristic acquisition unit 26 Second stability margin reading unit 50 Screen display unit 300 Frequency characteristic measurement unit 400 Adjustment unit

Claims

1. An adjustment support device that adjusts at least one filter coefficient and gain of a motor control device that controls the rotation of a motor, comprising: a frequency characteristic measurement unit that measures the frequency characteristics of the motor control device; a frequency characteristic acquisition unit that acquires the frequency characteristics before adjustment from the frequency characteristic measurement unit; a stability margin reading unit that reads a stability margin from the frequency characteristics acquired by the frequency characteristic acquisition unit; a stability margin setting unit that sets the stability margin read by the stability margin reading unit as a target margin for adjustment; and an adjustment unit that adjusts the gain and the filter coefficient based on the target margin.

2. An adjustment support device as described in claim 1, further comprising: a second frequency characteristic acquisition unit that acquires the frequency characteristics of the motor control device after adjustment by the adjustment unit from the frequency characteristic measurement unit; a second stability margin reading unit that reads a stability margin from the frequency characteristics acquired by the second frequency characteristic acquisition unit; and a screen display unit that displays information including at least one of the frequency characteristics and the stability margin before and after adjustment.

3. The adjustment support device according to claim 1 or 2, wherein at least one of a gain margin, a phase margin, a sensitivity peak value, and a maximum value of a closed loop characteristic is selected as the stability margin.

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