Motor control device

Abstract

A motor control device according to one embodiment of the present disclosure, capable of optimizing control characteristics, is provided with: a torque command creation unit that creates a torque command for driving a motor on the basis of an input speed command; an operation command creation unit that creates an operation command, which is the speed command input to the torque command creation unit, in order to operate the motor; a measurement command creation unit that creates a measurement command for adjustment by the torque command creation unit, the measurement command being the speed command input to the torque command creation unit or the torque command for driving the motor; a response characteristic calculation unit that calculates a response characteristic value indicating a response characteristic of the speed detection value of the motor with respect to the measurement command; and an amplitude determination unit that causes the measurement command creation unit to change the amplitude of the measurement command when the response characteristic value does not satisfy a predetermined determination condition.

Description

Technical Field

[0001] The invention relates to a motor control device. Background Art

[0002] Motor control devices that operate the motor at a target speed by performing feedback control on the current supplied to the motor are widely used. When the load of the motor changes, the response characteristics of the motor change. Therefore, it is desirable to be able to prevent resonance and appropriately control the speed of the motor by adjusting the parameters (set values) of the feedback loop, such as the gain and filter.

[0003] Therefore, the following technology is proposed: confirm the frequency response characteristics of the motor output relative to the target speed, and change the setting of the control loop so that the motor can be properly controlled. Specifically, the following technology is proposed (for example, refer to Patent Document 1): input a target speed for adjustment that changes in a sinusoidal shape to the control loop of the motor, scan the frequency of the target speed and detect the actual motor speed, thereby confirming the frequency response characteristics.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-128734 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] When confirming the frequency response characteristics of the motor, if the amplitude of the target speed is too small, the measurement error caused by friction, etc. may become larger. On the other hand, if the amplitude of the target speed is too large, there is a concern that the measurement error may become larger or oscillation may occur due to the structure used to support the motor, additional deflection, etc. Therefore, a technology that can optimize the control characteristics is desired.

[0009] Solutions for solving problems

[0010] A motor control device according to one embodiment of the present disclosure comprises: a torque instruction generating unit, which generates a torque instruction for driving a motor based on an input speed instruction; an operation instruction generating unit, which generates an operation instruction for operating the motor, the operation instruction being the speed instruction input to the torque instruction generating unit; a measurement instruction generating unit, which generates a measurement instruction for adjusting the torque instruction generating unit, the measurement instruction being the speed instruction input to the torque instruction generating unit or the torque instruction for driving the motor; a response characteristic calculating unit, which calculates a response characteristic value, the response characteristic value indicating a response characteristic of a speed detection value of the motor with respect to the measurement instruction; and an amplitude determining unit, which causes the measurement instruction generating unit to change the amplitude of the measurement instruction when the response characteristic value does not satisfy a prescribed determination condition.

[0011] Effects of the Invention

[0012] According to the present disclosure, control characteristics can be optimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a block diagram showing the configuration of a motor control device according to one embodiment of the present disclosure.

[0014] Figure 2 It means by Figure 1 Flowchart of a process of adjusting the amplitude of a measurement instruction performed by a motor control device. DETAILED DESCRIPTION

[0015] Below, with reference to the attached Figure 1 While explaining. Figure 1 It is a block diagram showing the configuration of a motor control device 1 according to one embodiment of the present disclosure.

[0016] The motor control device 1 controls the servo motor 3 via the servo amplifier 2. That is, the motor control device 1 inputs a torque command to the servo amplifier 2, the torque command being used to specify the torque required to operate the motor 3 at the target speed at that time. The motor control device 1 is configured to confirm the detection value of the speed detector 31 for detecting the speed of the motor 3 and perform feedback control for optimizing the torque command.

[0017] The motor control device 1 includes an operation command generating unit 11, a torque command generating unit 12, a feedback unit 13, a measurement command generating unit 14, a response characteristic calculating unit 15, an amplitude determining unit 16, and a parameter adjusting unit 17. The motor control device 1 can be realized by causing one or more computer devices having a memory, a processor, an input / output interface, etc. to execute an appropriate control program. The components of the motor control device 1 are obtained by classifying the functions of the motor control device 1, and may not be components that can be clearly distinguished in terms of physical structure and program structure.

[0018] The operation command generating unit 11 generates an operation command for operating the motor 3, and the operation command is a speed command input to the torque command generating unit. The operation command generating unit 11 reads the operation required for the motor 3, that is, data for determining the waveform of the change in the speed of the motor 3, such as an operation program described in the language of G code, and continuously outputs a value indicating the rotation speed of the motor 3 when the motor 3 is operated according to the operation program.

[0019] The torque command generating unit 12 generates a torque command for the motor according to the input speed command. The torque command generating unit 12 may also include an amplifier for amplifying the input or output, a filter for reducing a specific frequency component of the input or output, etc. In other words, the transfer function of the torque command generating unit 12 may also be another function, and the characteristic of the torque command generating unit 12, that is, the transfer function, can be adjusted by modifying one or more parameters.

[0020] The feedback unit 13 obtains the speed detection value of the speed detector 31, processes it as needed, and feeds it back to the torque instruction making unit 12. That is, the feedback unit 13 superimposes the speed detection value or the value obtained by processing the speed detection value on the operation instruction output from the operation instruction making unit 11 and inputs it to the torque instruction making unit 12. In a general structure, the speed detection value and the operation instruction are added in reverse phase. In addition, the feedback unit 13 can also convert the data format, bit rate, etc. of the detection value, and can also include an amplifier, a filter, etc. The transfer function of the feedback unit 13 can also be adjusted by modifying the parameters.

[0021] The measurement command generating unit 14 generates a measurement command for inputting an appropriate torque command to the servo amplifier 2 in order to adjust the parameters of the torque command generating unit 12 and the feedback unit 13. The measurement command may be a speed command input to the torque command generating unit 12 or a torque command directly input to the servo amplifier 2. The measurement command generating unit 14 of the present embodiment is configured to generate a speed command input to the torque command generating unit 12 based on data for determining the waveform, frequency, amplitude, etc. of the measurement command. The measurement command generating unit 14 may also be configured integrally with the operation command generating unit 11. That is, the measurement command generating unit 14 may also be configured to generate the measurement command by making the operation command generating unit 11 refer to different data.

[0022] As the measurement command, a periodic vibration command such as a sine wave, a rectangular wave, a triangular wave, a ramp command of a fixed acceleration, a pulse command, an M-sequence signal-like command with irregularity, etc. is selected according to the response characteristic value calculated in the response characteristic calculation unit 15, but a sine wave signal can be typically used. In addition, the measurement command preparation unit 14 is preferably configured to sweep the frequency of the periodic measurement command in order to calculate the response characteristic value representing the frequency response characteristic in the response characteristic calculation unit 15, that is, to change the frequency continuously.

[0023] The measurement command generation unit 14 is configured to be able to change the amplitude of the measurement command according to the instruction from the amplitude determination unit 16. The measurement command generation unit 14 preferably sets the initial value of the amplitude of the measurement command to a sufficiently small value, and gradually increases the amplitude of the measurement command according to the instruction from the amplitude determination unit 16. Thus, the amplitude of the appropriate measurement command can be determined while suppressing the divergence of the response with relatively simple control.

[0024] The response characteristic calculation unit 15 calculates a response characteristic value indicating the response characteristic of the speed detection value with respect to the measurement command. The response characteristic calculation unit 15 preferably calculates at least one of the gain and the phase difference of the speed detection value with respect to the sinusoidal measurement command for each frequency of the measurement command as the response characteristic value, that is, calculates the frequency response characteristic. Based on the frequency response characteristic calculated by the response characteristic calculation unit 15, the amplitude of the measurement command is optimized, thereby appropriately optimizing the control loop based on the known technology and utilizing the frequency response characteristic.

[0025] When the response characteristic value does not satisfy the predetermined determination condition, the amplitude determination unit 16 causes the measurement command creation unit 14 to change the amplitude of the measurement command. As described above, it is preferable that the initial value of the amplitude of the measurement command is set to a sufficiently small value, and the amplitude determination unit 16 is configured to increase the amplitude when the response characteristic value does not satisfy the determination condition.

[0026] The judgment condition may also be that the difference between the maximum value and the minimum value of the gain is less than a predetermined judgment threshold. When the amplitude of the measurement instruction is inappropriate, the gain in a specific frequency domain may become abnormally small due to the influence of friction, for example, or abnormally large due to the influence of mechanical resonance, for example. Therefore, when the difference between the maximum value and the minimum value of the gain is small enough, it can be judged that such an inappropriate phenomenon does not occur.

[0027] The judgment condition may also be: the gain of a preset frequency range is greater than a preset judgment threshold. In addition, the judgment condition may also be: the ratio of the gain of a preset frequency range to the gain of other frequency ranges or the full frequency range is greater than a preset judgment threshold. For example, there are many frequency ranges where it is foreseeable that a reduction in gain due to friction or the like will occur. Therefore, when the ratio of the gain of the preset frequency range to the gain of other frequency ranges is large enough, it can be determined that the envisioned adverse effects due to friction or the like have not occurred.

[0028] The judgment condition may also be: the gain at the initial stage of the frequency scan of the measurement instruction is greater than a predetermined judgment threshold. For example, the reduction in gain due to friction or the like is particularly likely to occur in the low-frequency domain. Therefore, if the gain at the initial stage of the frequency scan is sufficiently large, it can be judged that the expected adverse effects due to friction or the like have not occurred.

[0029] The judgment condition may also be that the difference between the representative value of the gain before the amplitude of the measurement command is changed and the representative value of the gain after the amplitude of the measurement command is changed is less than a predetermined judgment threshold. For example, the amount of gain reduction caused by friction or the like often changes according to the amplitude of the measurement command. Therefore, when the gain does not change significantly even when the amplitude of the measurement command is changed, it can be judged that the adverse effect caused by friction or the like as expected does not occur.

[0030] The amplitude determination unit 16 may also be configured to restore the amplitude of the measurement command to the previous value when the response characteristic value reaches a preset limit value, and to reduce the amount of change in the amplitude of the measurement command when the determination condition is not satisfied. When the response characteristic value reaches a preset limit value, for example, when the gain or phase difference becomes too large, there is a high possibility that the amount of change in the amplitude of the measurement command is too large and passes through the optimal amplitude. Therefore, it is preferred to restore the amplitude of the measurement command to the previous value, reduce the amount of change in the amplitude, and search again for the optimal amplitude of the measurement command.

[0031] The amplitude determination unit 16 can set the change amount of the amplitude of the measurement command to a fixed value, or can set the change amount of the amplitude of the measurement command to an increasing function, such as a linear function or a quadratic function, with the current value of the amplitude as a variable. By optimizing the change amount of the amplitude of the measurement command in this way, the appropriate amplitude of the measurement command can be effectively determined.

[0032] The amplitude determination unit 16 may adjust the change amount of the amplitude of the measurement command according to the response characteristic value. For example, when it is determined that the gain is excessively small, it is conceivable that the appropriate amplitude of the measurement command can be determined more effectively by increasing the change amount of the amplitude.

[0033] The amplitude determination unit 16 may also be configured to stop the output of the measurement instruction by the measurement instruction generating unit 14 when it is determined that the determination condition is not satisfied. As an example, when the amplitude determination unit 16 determines that the determination condition is not satisfied in the middle of the frequency scan of the measurement instruction, it may also end the amplitude adjustment of the measurement instruction without waiting for the completion of the frequency scan of the measurement instruction. In addition, after the amplitude adjustment is completed, it is also possible to immediately start the measurement instruction generating unit 14 to adjust the parameters of the speed control loop without setting a stop period. Specifically, it is also possible to start outputting the measurement instruction for adjusting the parameters by the parameter adjustment unit 17 at the same time as the completion of the frequency scan of the measurement instruction when the amplitude determination unit 16 determines that the determination condition is satisfied.

[0034] The parameter adjustment unit 17 causes the measurement instruction generation unit 14 to output the measurement instruction of the amplitude optimized by the amplitude determination unit 16, confirms the speed detection value of the speed detector 31, the response characteristic value calculated by the response characteristic calculation unit 15, etc., and adjusts the parameters of at least one of the torque instruction generation unit 12 and the feedback unit 13, thereby improving the control characteristics of the motor 3 by the motor control device 1. Such adjustment of the control characteristics can be performed based on a known technique. By using the measurement instruction of the amplitude optimized by the amplitude determination unit 16, it is possible to ensure appropriate adjustment of the control characteristics.

[0035] exist Figure 2 2 shows the process of amplitude adjustment of the measurement command performed by the motor control device 1. The amplitude adjustment of the measurement command includes an amplitude initialization step (step S1), a response characteristic measurement step (step S2), a limit value confirmation step (step S3), a change amount correction step (step S4), an amplitude recovery step (step S5), an amplitude determination step (step S6), and an amplitude change step (step S7).

[0036] In the amplitude initialization process of step S1 , the amplitude of the measurement command of the measurement command generating unit 14 is set to an initial value.

[0037] In the response characteristic measurement process of step S2 , the measurement command generation unit 14 is caused to output a measurement command, and the response characteristic calculation unit 15 calculates a response characteristic value.

[0038] In the limit value confirmation process of step S3, it is confirmed whether the response characteristic value has reached the limit value. If the response characteristic value has reached the limit value, the process proceeds to step S4, and if the response characteristic value has not reached the limit value, the process proceeds to step S6.

[0039] In the change amount correction process of step S4 , the amplitude determination unit 16 changes the setting so that the change amount of the amplitude of the measurement command becomes smaller.

[0040] In the amplitude recovery process of step S5, the amplitude of the measurement command of the measurement command generating unit 14 is recovered to the previous amplitude, that is, to the amplitude before the last execution of step S6. When the amplitude recovery process is executed, the process returns to step S2 and starts again from the measurement of the response characteristic value.

[0041] In the amplitude determination process of step S6, the response characteristic value is evaluated by the amplitude determination unit 16, and it is determined whether the amplitude of the measurement command needs to be changed. If it is determined that the amplitude of the measurement command needs to be changed, the process proceeds to step S7. If it is determined that the amplitude of the measurement command does not need to be changed, the output of the measurement command by the measurement command creation unit 14 is stopped, and the amplitude adjustment process is terminated.

[0042] In the amplitude changing process of step S7, after the amplitude of the measurement command of the measurement command generating unit 14 is changed, the process returns to step S2 and starts again from measuring the response characteristic value.

[0043] exist Figure 2 After the amplitude adjustment is completed, the parameter adjustment unit 17 automatically adjusts the known control parameters using the measurement command.

[0044] As described above, in the motor control device 1 that performs amplitude adjustment, the amplitude of the measurement command used for automatic adjustment of the control parameter is optimized, so that the control characteristics can be reliably optimized in accordance with the motor 3 and its load.

[0045] Regarding the above-mentioned embodiment, the following supplementary notes are further disclosed.

[0046] (Note 1)

[0047] The motor control device (1) comprises: a torque instruction generating unit (12) which generates a torque instruction for driving a motor based on an input speed instruction; an operation instruction generating unit (11) which generates an operation instruction for operating the motor, wherein the operation instruction is a speed instruction input to the torque instruction generating unit (12); a measurement instruction generating unit (14) which generates a measurement instruction for adjusting the torque instruction generating unit (12), wherein the measurement instruction is a speed instruction input to the torque instruction generating unit (12) or a torque instruction for driving the motor; a response characteristic calculating unit (15) which calculates a response characteristic value, wherein the response characteristic value indicates a response characteristic of a speed detection value relative to the measurement instruction; and an amplitude determining unit (16) which causes the measurement instruction generating unit (14) to change the amplitude of the measurement instruction when the response characteristic value does not satisfy a predetermined determination condition.

[0048] (Note 2)

[0049] The measurement command may be a sinusoidal command having a swept frequency, and the response characteristic calculation unit may calculate at least one of a gain and a phase difference of the speed detection value with respect to the measurement command as the response characteristic value for each frequency of the measurement command.

[0050] (Note 3)

[0051] The determination condition may be that the difference between the maximum value and the minimum value of the gain is equal to or smaller than a predetermined determination threshold value.

[0052] (Note 4)

[0053] The determination condition may be that the gain in a preset frequency range is equal to or greater than a preset determination threshold value.

[0054] (Note 5)

[0055] The determination condition may be that a ratio of a gain in a preset frequency range to a gain in another frequency range or in the entire frequency range is equal to or greater than a preset determination threshold.

[0056] (Note 6)

[0057] The determination condition may be that the gain at the initial stage of scanning of the frequency of the measurement command is equal to or greater than a predetermined determination threshold value.

[0058] (Note 7)

[0059] The determination condition may be that a difference between a representative value of the gain before the amplitude of the measurement command is changed and a representative value of the gain after the amplitude of the measurement command is changed is equal to or less than a predetermined determination threshold.

[0060] (Note 8)

[0061] When the amplitude determination unit (16) determines that the determination condition is satisfied, the measurement command generation unit (14) may stop outputting the measurement command.

[0062] (Note 9)

[0063] When the response characteristic value reaches a preset limit value, the amplitude determination unit (16) may restore the amplitude of the measurement command to a previous value, and may reduce the amount of change in the amplitude of the measurement command when the determination condition is not satisfied.

[0064] (Note 10)

[0065] The amplitude determination unit (16) may set the amount of change in the amplitude of the measurement command to a fixed value or to a value of an increasing function with the current value of the amplitude as a variable.

[0066] (Note 11)

[0067] The amplitude determination unit (16) may adjust the amount of change in the amplitude of the measurement command according to the response characteristic value.

[0068] The present disclosure has been described in detail above, but the present disclosure is not limited to the above-mentioned embodiments. These embodiments can be variously added, replaced, changed, or partially deleted without departing from the gist of the present disclosure, or without departing from the gist of the present disclosure derived from the contents recorded in the claims and their equivalents. In addition, these embodiments can also be implemented in combination. For example, in the above-mentioned embodiments, the order of each action and the order of each processing are shown as an example and are not limited to these orders. In addition, the same is true for the use of numerical values ​​or formulas in the description of the above-mentioned embodiments.

[0069] As an example, the motor control device according to the present disclosure may be configured to perform open loop control without providing feedback to the torque command generating unit when the motor is operated according to the operation program.

[0070] Description of Reference Numerals

[0071] 1: Motor control device; 11: Operation instruction generation unit; 12: Torque instruction generation unit; 13: Feedback unit; 14: Measurement instruction generation unit; 15: Response characteristic calculation unit; 16: Amplitude determination unit; 17: Parameter adjustment unit; 2: Servo amplifier; 3: Servo motor; 31: Speed ​​detector.

Claims

1. A motor control device comprising: a torque command generating unit that generates a torque command for driving the motor based on the input speed command; an operation command generating unit configured to generate an operation command for operating the motor, wherein the operation command is the speed command input to the torque command generating unit; a measurement command generating unit configured to generate a measurement command for adjusting the torque command generating unit, wherein the measurement command is the speed command input to the torque command generating unit or the torque command for driving the motor; a response characteristic calculation unit that calculates a response characteristic value indicating a response characteristic of a speed detection value of the motor with respect to the measurement command; and The amplitude determination unit causes the measurement command generation unit to change the amplitude of the measurement command when the response characteristic value does not satisfy a predetermined determination condition.

2. The motor control device according to claim 1, wherein: The measurement instruction is a sinusoidal wave instruction with swept frequency. The response characteristic calculation unit calculates at least one of a gain and a phase difference of the speed detection value with respect to the measurement command as the response characteristic value for each frequency of the measurement command.

3. The motor control device according to claim 2, wherein: The determination condition is that a difference between a maximum value and a minimum value of the gain in a preset frequency range is equal to or less than a preset determination threshold value.

4. The motor control device according to claim 2, wherein: The determination condition is that the gain in a preset frequency range is equal to or greater than a preset determination threshold.

5. The motor control device according to claim 2, wherein: The determination condition is that a ratio of the gain in a preset frequency range to the gain in other frequency ranges or in the entire frequency range is equal to or greater than a preset determination threshold.

6. The motor control device according to claim 2, wherein: The determination condition is that the gain at an initial stage of scanning of the frequency of the measurement instruction is equal to or greater than a predetermined determination threshold.

7. The motor control device according to claim 2, wherein: The determination condition is that a difference between a representative value of the gain before the amplitude of the measurement command is changed and a representative value of the gain after the amplitude of the measurement command is changed is equal to or smaller than a predetermined determination threshold.

8. The motor control device according to any one of claims 1 to 7, wherein: When the amplitude determination unit determines that the determination condition is not satisfied, the measurement command generation unit causes the measurement command generation unit to stop outputting the measurement command.

9. The motor control device according to any one of claims 1 to 8, wherein: The amplitude determination unit returns the amplitude of the measurement command to a previous value when the response characteristic value reaches a preset limit value, and reduces the amount of change in the amplitude of the measurement command when the determination condition is not satisfied.

10. The motor control device according to any one of claims 1 to 9, wherein: The amplitude determination unit sets the amount of change in the amplitude of the measurement command to a fixed value or to a value of an increasing function using a current value of the amplitude as a variable.

11. The motor control device according to any one of claims 1 to 10, wherein: The amplitude determination unit adjusts an amount of change in the amplitude of the measurement instruction according to the response characteristic value.

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