Motor control device and motor control method

Abstract

The motor control device of the present invention suppresses the situation where the control becomes unstable. The servo amplifier (100) that adjusts the gain of the motor (300) analyzes the feedback signal. When it is determined that there is vibration above a certain reference level, the torque adjustment unit (140) makes the intensity of the notch filter (141) stronger than the initial setting when the peak frequency of the adjacent vibration determined by the servo amplifier (100) is within a certain range, thereby covering and attenuating the peak frequency of the vibration within a certain range.

Description

Technical Field

[0001] This invention relates to a motor control device and a motor control method with automatic tuning function. Background Technology

[0002] When installing servo system motors on objects such as robots or machine tools, the gain of the servo amplifier needs to be adjusted according to the load inertia. This gain adjustment of the servo amplifier is mostly performed by a motor control device with automatic tuning function.

[0003] In automatic tuning, multiple test actions are performed while changing the tuning parameters, and the parameters to be set next are determined based on the results of the various test actions. In particular, in order to suppress oscillations on the motor side at the resonant points present in the target device, it is necessary to set a notch filter that can suppress resonant peaks, for example.

[0004] As a technology related to such automatic tuning, Patent Document 1 proposes an automatic adjustment method for a motor control device as follows: the encoding unit extracts and outputs information about the symbols of internal state quantities; the limiting unit calculates and outputs information about limiting the amplitude of the output of the notch filter unit; the adaptive update unit updates and outputs a predicted value of the notch frequency based on the result of multiplying the output of the encoding unit and the output of the limiting unit; the notch filter unit uses the predicted value as the notch frequency; the unit conversion unit converts the unit of the predicted value to Hertz and outputs it as the predicted value; and the controller is adaptively adjusted using the predicted value.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2021-087276 Summary of the Invention

[0008] In the automatic adjustment method of the motor control device in the aforementioned Patent Document 1, since the notch frequency of the notch filter is set near the frequency of the resonant point of the target device, it is believed that the frequency level of the resonant point can be attenuated.

[0009] However, when there are multiple resonant points of the target device within a certain range, even if the notch frequency of the notch filter is set near the frequency of the resonant point, the frequency level of the resonant points within a certain range cannot be attenuated, and the control may become unstable.

[0010] The present invention was made in view of the above-mentioned situation, and its object is to provide a motor control device and a motor control method that can eliminate the above-mentioned problems.

[0011] The motor control device of the present invention is characterized by comprising: a servo amplifier that adjusts the gain of the motor; and a torque adjustment unit having a notch filter, wherein the servo amplifier analyzes the feedback signal to determine whether there is vibration above a certain reference level, and the torque adjustment unit makes the intensity of the notch filter stronger than the initial setting when the peak frequency of the adjacent vibration determined by the servo amplifier is within a certain range.

[0012] The motor control method of the present invention is characterized in that, by adjusting the gain of the motor through a servo amplifier, the feedback signal is analyzed to determine whether there is vibration above a certain reference level, and by using a torque adjustment unit with a notch filter, when the peak frequency of the adjacent vibrations determined by the servo amplifier is within a certain range, the strength of the notch filter is made stronger than the initial setting.

[0013] In the motor control device and motor control method of the present invention, a servo amplifier that adjusts the gain of the motor is used to analyze the feedback signal and determine whether there is vibration above a certain reference level. When the peak frequency of the adjacent vibration determined by the servo amplifier is within a certain range, the torque adjustment unit with a notch filter makes the strength of the notch filter stronger than the initial setting.

[0014] According to the motor control device and motor control method of the present invention, since the peak frequency of vibration within a certain range is covered and attenuated, it is possible to suppress the situation where the control becomes unstable. Attached Figure Description

[0015] Figure 1 This is a diagram illustrating one embodiment of the motor control device of the present invention.

[0016] Figure 2A It is used to explain by Figure 1 The diagram showing the torque adjustment of the servo amplifier for vibration frequencies exceeding a certain reference level is a diagram illustrating the case of setting a notch filter for a vibration.

[0017] Figure 2B It is used to explain by Figure 1 The diagram showing the torque adjustment of the servo amplifier for vibration frequencies exceeding a certain reference level is a diagram illustrating the case where a second vibration exists at a position above a certain range relative to the first vibration.

[0018] Figure 2C It is used to explain by Figure 1 The diagram showing the torque adjustment of the servo amplifier for vibration frequencies exceeding a certain reference level is a diagram illustrating the case of setting a notch filter for the second vibration.

[0019] Figure 3A It is used to explain by Figure 1 The diagram shows the torque adjustment of the servo amplifier for vibration frequencies exceeding a certain reference level, and the diagram shows the notch filter when the peak frequencies of adjacent vibrations are set within a certain range.

[0020] Figure 3B It is used to explain by Figure 1 The diagram shows the torque adjustment of the servo amplifier for vibration frequencies exceeding a certain reference level, and the diagram shows the notch filter when the peak frequencies of adjacent vibrations are set within a certain range.

[0021] Figure 3C It is used to explain by Figure 1 The diagram shows the torque adjustment of the servo amplifier for vibration frequencies exceeding a certain reference level, and the diagram shows the notch filter when the peak frequencies of adjacent vibrations are set within a certain range.

[0022] Figure 4 It is used to explain by Figure 1 The flowchart shows the automatic tuning process of the servo amplifier. Detailed Implementation

[0023] The following reference Figures 1-4 This section describes one embodiment of the motor control device of the present invention. Furthermore, when the motor control device M described below performs automatic tuning, it needs to adjust the gain of the servo amplifier 100 according to the load inertia; however, for ease of explanation, illustrations and descriptions regarding load inertia are omitted. Additionally, the frequency values ​​described below are values ​​that are easy to explain.

[0024] The motor control unit M includes a servo amplifier 100 with automatic tuning function. The servo amplifier 100 performs FFT (Fast Fourier Transform) analysis on the encoder pulses used as feedback signals and extracts the vibration frequency. Furthermore, when the peak value of the extracted vibration frequency exceeds a certain reference level, the servo amplifier 100 determines it to be oscillation. Additionally, reference numeral 300 indicates the motor, reference numeral 150 indicates the subtractor, and reference numeral 160 indicates the adder / subtractor.

[0025] The servo amplifier 100 includes a position adjustment unit 110, a feedforward control unit 120, a feedback control unit 130, a torque adjustment unit 140, and a current control unit 170.

[0026] The position adjustment unit 110 outputs a position command corresponding to the gain setting to the feedforward control unit 120 and the subtractor 150 based on a target value command that shows command values ​​including position, speed and torque from a controller (not shown).

[0027] Based on the position command from the position adjustment unit 110, the feedforward control unit 120 outputs a feedforward command (FF command) to the adder / subtractor 160, which includes a speed command and a torque command for controlling speed and torque.

[0028] Based on the feedback signal, the feedback control unit 130 outputs a feedback command (FB command) to the adder / subtractor 160 to make the deviation from the subtractor 150 zero.

[0029] The torque adjustment unit 140 has first and second notch filters 141 and 142. In response to vibrations contained in the torque command of the control command from the adder / subtractor 160, the torque adjustment unit 140 outputs an adjustment command attenuated by notch filters 141 and / or 142 to the current control unit 170.

[0030] Furthermore, the first and second notch filters 141 and 142 are not limited to the two shown in the figure; more than three can be provided. Additionally, as the first notch filter 141 and the second notch filter 142, adaptive filters capable of adapting their transfer functions according to an optimization algorithm can be used. Detailed specifications for the first notch filter 141 and the second notch filter 142 will be described later.

[0031] Subtractor 150 subtracts the position and speed signals from the position command and feedback signal corresponding to the gain setting from position adjustment unit 110, and outputs the deviation. Adder / subtractor 160 performs subtraction on the feedforward command and feedback command, and outputs a control command to make the deviation from subtractor 150 zero.

[0032] The current control unit 170 controls the drive current of the motor 300 to generate the torque indicated by the adjustment command from the torque adjustment unit 140.

[0033] When this type of motor control device outputs a command from a controller (not shown), the motor 300 starts to drive based on the feedforward command (FF command) from the feedforward control unit 120.

[0034] When a feedback signal detected by an encoder (not shown) is output along with the drive of the motor 300, a control command for making the deviation from the subtractor 150 zero is output from the adder / subtractor 160 according to the feedback command (FB command) from the feedback control unit 130. Then, the current control unit 170 controls the drive current of the motor 300 to generate the torque indicated by the adjustment command after vibration damping from the torque adjustment unit 140.

[0035] Next, refer to Figures 2A to 3C The settings of the torque adjustment unit 140 will be explained. Furthermore, for ease of explanation, Figures 2A to 3COnly vibrations exceeding a certain reference level are shown. Additionally, the vertical axis shows the vibration level and the depth of the first notch filter 141 and the second notch filter 142, while the horizontal axis shows the frequency.

[0036] Furthermore, the first notch filter 141 and the second notch filter 142 have the characteristic of phase lag on the low-frequency side (below the center frequency) and phase lead on the high-frequency side (above the center frequency). Therefore, when the notch frequencies of the first notch filter 141 and the second notch filter 142 are made to match the peak frequency of the vibration, the notch frequencies do not match the peak frequency of the vibration due to the phase lag on the low-frequency side, and sometimes the servo amplifier 100 becomes unstable. Therefore, in this embodiment, the notch frequencies of the first notch filter 141 and the second notch filter 142 are set to, for example, frequencies that are 90% of the peak frequency of the vibration.

[0037] In addition, such as Figure 2A As shown, the so-called 90% frequency, for example, when the peak frequency of vibration is 400Hz, the notch filter frequency is set to 360Hz. Thus, after setting the first notch filter 141 and the second notch filter 142, the phase of the notch filter frequency can be made to match the peak frequency of vibration.

[0038] Figure 2A The illustration shows a case where the servo amplifier 100 experiences only one vibration due to oscillation. In this case, the torque adjustment unit 140 sets the notch frequency of the first notch filter 141 to 90% of the peak frequency of the vibration (400Hz) (360Hz). Therefore, after setting the first notch filter 141, the phase of the notch frequency can be made to match the peak frequency of the vibration, such as... Figure 2B As shown by the dashed line, it can attenuate the peak frequency (400Hz) of the vibration.

[0039] Figure 2B This illustrates a case where the servo amplifier 100 experiences two vibrations due to oscillation. In this case, as... Figure 2C As shown, when the peak frequency of the second vibration (800Hz) is more than a certain range away from the peak frequency of the first vibration (400Hz), the torque adjustment unit 140 sets the notch frequency of the second notch filter 142 to 90% of the peak frequency of the vibration (800Hz) (720Hz). Therefore, after setting the second notch filter 142, the peak frequency of the second vibration (800Hz) can be attenuated. Here, "more than a certain range away" means, for example, that the peak frequencies of the two vibrations are more than twice the bandwidth of the notch frequency.

[0040] Furthermore, in automatic tuning, after setting the first notch filter 141, the gain of the first notch filter 141 is increased to perform a test operation. The tuning operation ends when it is confirmed that there is no vibration with a peak value exceeding a certain reference level in the FFT analysis result of the torque value obtained from the feedback signal. Additionally, when performing the test operation on the first notch filter 141, such as... Figure 2B In the case of a second vibration, after setting the second notch filter 142 to 90% of the peak frequency (800Hz) of the second vibration (720Hz), the gain of the second notch filter 142 is increased to perform the test operation. When it can be confirmed that there is no vibration with a peak exceeding a certain reference level, the tuning operation ends.

[0041] then, Figure 3A This illustrates a case where the servo amplifier 100 experiences two vibrations due to oscillation, and the peak frequencies of the two vibrations are close (within a certain range). "Within a certain range" means, for example, that the peak frequencies of the two vibrations are within the notch filter frequency band.

[0042] like Figure 3A As shown, when the peak frequencies of the two vibrations are close, the torque adjustment unit 140 sets the notch frequency of the first notch filter 141 to 90% of the peak frequency of the vibration (400Hz) (360Hz). Therefore, after setting the first notch filter 141, as... Figure 3B As shown by the dashed line, it can attenuate the peak frequency (400Hz) of the vibration.

[0043] Here, the test is performed by increasing the gain of the first notch filter 141. And, as... Figure 3B As shown, based on the FFT analysis results of the torque value obtained from the feedback signal, when there is no attenuation of vibration near the peak frequency (400Hz), the torque adjustment unit 140... Figure 3C As shown, the strength of the first notch filter 141 is made stronger than initially set. Therefore, as... Figure 3B As shown by the solid line, the notch frequency becomes deeper, thus enabling it to cover and attenuate the peak frequency of vibrations that is close to (within a certain range) the peak frequency of the vibration (400Hz).

[0044] Furthermore, if the peak frequencies of the two vibrations generated by the oscillation of the servo amplifier 100 are close (within a certain range), it is also possible to set the notch frequency of the first notch filter 141 to the lower of the vibration peak frequencies. However, if the first notch filter 141 is set to the lower of the vibration peak frequencies, even if the notch frequency depth is deep, the notch frequency may not be able to cover the higher vibration peak frequency. Therefore, it is preferable to align the first notch filter 141 with the higher vibration peak frequency side.

[0045] Next, refer to Figure 4 The automatic tuning process of the motor control device M will be explained. Additionally, the following section explains the situation related to vibration reduction based on torque adjustment.

[0046] (Step S101)

[0047] Servo amplifier 100 analyzes vibration level.

[0048] In this case, the servo amplifier 100 performs FFT analysis on the feedback signal, for example, to extract the vibration frequency.

[0049] (Step S102)

[0050] Servo amplifier 100 determines whether there is vibration above a certain reference level.

[0051] In this case, when the peak value of the extracted vibration frequency does not exceed a certain reference level, the servo amplifier 100 determines that there is no vibration above a certain reference level (step S102: No) and ends the process.

[0052] In contrast, such as Figures 2A to 3C As shown, when the peak value of the extracted vibration frequency exceeds a certain reference level, the servo amplifier 100 determines that there is vibration above a certain reference level (step S102: yes), and proceeds to step S103.

[0053] (Step S103)

[0054] Servo amplifier 100 determines whether there are two or more vibrations.

[0055] In this case, the servo amplifier 100, based on the judgment result of step S107, such as... Figure 2A As shown, when it is determined that the vibration is a (step S103: no), proceed to step S107.

[0056] In contrast, the servo amplifier 100, based on the judgment result of step S102, such as... Figure 2BAs shown, when it is determined that there are two or more vibrations (step S103: yes), proceed to step S104.

[0057] (Steps S104, S107)

[0058] Servo amplifier 100 sets the first notch filter 141.

[0059] In this case, such as Figure 2A As shown, the torque adjustment unit 140 of the servo amplifier 100 sets the notch frequency of the first notch filter 141 to 90% of the peak frequency of the vibration (400Hz) (360Hz).

[0060] Then, after setting the first notch filter 141, the gain of the first notch filter 141 is increased to perform the test action to confirm whether the vibration at the peak frequency (400Hz) of the first notch filter 141 is attenuated.

[0061] In addition, the process ends when the setting of the first notch filter 141 is completed and vibration attenuation is confirmed in step S107.

[0062] (Step S105)

[0063] Servo amplifier 100 determines whether the peak frequency of the second vibration is within a certain range.

[0064] In this case, servo amplifier 100, such as Figure 3A As shown, when it is determined that the peak frequency of the second vibration is within a certain range (close) to the peak frequency (400Hz) of the first vibration (step S105: yes), the process proceeds to step S106.

[0065] In contrast, the servo amplifier 100, such as Figure 2B As shown, when it is determined that the peak frequency of the second vibration (800Hz) is above a certain range relative to the peak frequency of the first vibration (400Hz) (step S105: No), proceed to step S108.

[0066] (Step S106)

[0067] Servo amplifier 100 sets the second notch frequency.

[0068] In this case, such as Figure 2C As shown, the torque adjustment unit 140 of the servo amplifier 100 sets the notch frequency of the second notch filter 142 to 90% of the peak frequency (800Hz) of the second vibration (720Hz).

[0069] Then, after setting the second notch filter 142, the gain of the second notch filter 142 is increased to perform the test to confirm whether the vibration at the peak frequency (800Hz) of the second notch filter 142 is attenuated.

[0070] (Step S108)

[0071] Servo amplifier 100 enhances the strength of first notch filter 141.

[0072] In this case, such as Figure 3C As shown, the torque adjustment section 140 of the servo amplifier 100 makes the strength of the first notch filter 141 stronger than the initial setting.

[0073] Therefore, by increasing the depth of the notch frequency of the first notch filter 141, after setting the first notch filter 141, it is possible to cover the peak frequency of vibration (400Hz) that is close to the peak frequency of vibration (within a certain range) and attenuate it.

[0074] (Step S109)

[0075] Servo amplifier 100 determines whether the setting is complete.

[0076] In this case, if the servo amplifier 100 cannot confirm in steps S104, S106 and S107 that the vibration of the peak frequency (400Hz and 800Hz, or 400Hz) is attenuated due to the setting of the first notch filter 141 and / or the second notch filter 142 (step S109: No), it is determined that the setting is not completed.

[0077] In contrast, if the servo amplifier 100 can confirm in steps S104, S106, and S107 that the vibration of the peak frequency (400Hz and 800Hz, or 400Hz) is attenuated due to the setting of the first notch filter 141 and / or the second notch filter 142 (step S109: Yes), then it determines that the setting is complete and ends the process.

[0078] Furthermore, in the above description, in steps S104, S106, and S107, the test operation is performed by setting the first notch filter 141 and / or the second notch filter 142 and increasing the gain of the first notch filter 141 and / or the second notch filter 142, but this is not limited to this example. For example, in steps S104, S106, and S107, after setting the first notch filter 141 and / or the second notch filter 142, the test operation can be performed by increasing the gain of the first notch filter 141 and / or the second notch filter 142 in step S109 to confirm whether the vibration of the peak frequency of the first notch filter 141 and / or the second notch filter 142 is attenuated, and to determine whether the setting is completed.

[0079] Thus, in this embodiment, the servo amplifier 100, which adjusts the gain of the motor 300, analyzes the feedback signal. When it determines that there is vibration above a certain reference level, the torque adjustment unit 140, when the peak frequency of adjacent vibrations determined by the servo amplifier 100 is within a certain range, increases the strength of the notch filter 141 by more than the initial setting, thereby covering and attenuating the peak frequency of vibrations within a certain range. This suppresses situations where control becomes unstable.

[0080] Label Explanation

[0081] 100 Servo Amplifier

[0082] 110 Position Adjustment Section

[0083] 120 Feedforward Control Unit

[0084] 130 Feedback Control Department

[0085] 140 Torque Adjustment Unit

[0086] 141 First Notch Filter

[0087] 142 Second Notch Filter

[0088] 150 Subtractor

[0089] 160 Adder / Subtractor

[0090] 170 Current Control Unit

[0091] 300 motor

[0092] M motor control device.

Claims

1. A motor control device, characterized in that, have: A servo amplifier that adjusts the gain of the motor; and The torque adjustment unit includes a notch filter. The servo amplifier analyzes the feedback signal to determine whether there is vibration above a certain reference level. When the torque adjustment unit identifies two vibration modes with different peak frequencies in the feedback signal, and the peak frequency difference between the two vibration modes is within a certain range, the notch frequency of the notch filter is set to correspond only to the peak frequency of one of the two vibration modes. Furthermore, the vibration of the two vibration modes is attenuated by adjusting only the intensity of the notch filter, which has a notch frequency set only to correspond to the peak frequency.

2. The motor control device as described in claim 1, characterized in that, When the servo amplifier determines that there is vibration, the torque adjustment unit sets the notch frequency to a frequency that is a certain percentage smaller than the corresponding peak frequency.

3. The motor control device as described in claim 1, characterized in that, The torque adjustment unit makes the notch frequency correspond to the side with the higher peak frequency of the two vibration modes.

4. A motor control method, characterized in that, By adjusting the gain of the servo amplifier used for the motor and analyzing the feedback signal, it can be determined whether there is vibration above a certain reference level. By using a torque adjustment unit with a notch filter, when two vibration modes with different peak frequencies are identified in the feedback signal, and the peak frequency difference between the two vibration modes is within a certain range, the notch frequency of the notch filter is made to correspond only to the peak frequency of one of the two vibration modes, and the vibration of the two vibration modes is attenuated by adjusting only the intensity of the notch filter with a notch frequency set only to the peak frequency.

5. The motor control method as described in claim 4, characterized in that, When the servo amplifier detects the vibration, the torque adjustment unit sets the notch frequency to a frequency that is a certain percentage smaller than the corresponding peak frequency.

Images