A jitter suppression method employing a dynamic bandpass filter and a repetitive controller

Abstract

This invention relates to the field of industrial control technology, particularly to a jitter suppression function applied to the torque control of a permanent magnet synchronous motor driven by a servo controller. This technology detects the jitter speed using a bandpass filter. The pass frequency of the bandpass filter is calculated from the steady-state speed of the motor; the higher the motor speed, the higher the frequency of the bandpass filter. A repetitive controller is used to control the jitter speed, with the control target set to 0. The output of the repetitive controller serves as the periodic disturbance torque. This jitter suppression method can eliminate periodic disturbance torque caused by mechanical or electrical factors. Simultaneously, a frequency multiplication factor is introduced to suppress periodic jitter caused by different mechanical reduction ratios, demonstrating strong versatility. During operation, the disturbance frequency is dynamically adjusted, resulting in a strong suppression effect at different speeds. The introduction of a repetitive controller for jitter suppression significantly enhances the system's robustness and makes the load-side operation smoother.

Description

Technical Field

[0001] This invention relates to the field of industrial control technology, and in particular to the jitter suppression function applied to the torque control of a permanent magnet synchronous motor driven by a servo controller. Background Technology

[0002] In the torque control mode of a permanent magnet synchronous motor, the motor needs to accurately track the user's torque command to ensure that the output torque matches the command. However, due to errors in the servo driver's current sensor or periodic disturbances in the mechanical reducer, the actual output torque of the motor often exhibits periodic fluctuations, which affects the system's stability and control accuracy. Several methods exist for suppressing periodic jitter:

[0003] (1) Optimize the accuracy of the current sensor inside the driver, or optimize the mechanical accuracy, such as optimizing the dynamic balance of the rollers. This method is often effective for specific problems, but its limitations are obvious, as it can only solve vibrations caused by specific factors.

[0004] (2) Notch filter. A notch filter is introduced into the control system to suppress harmonics at specific frequencies. This method can effectively eliminate high-frequency resonances caused by increased controller bandwidth, but it does not significantly improve the performance of low- and medium-frequency disturbances.

[0005] (3) Proportional-Integral Resonant Controller (PIRC). PIRC combines the advantages of proportional-integral (PI) controllers and resonant controllers, enabling precise control of harmonics at specific frequencies. By adjusting the parameters of the resonant controller, the suppression of harmonics at different frequencies can be achieved. However, since PIRC proportional-integral control is itself a complex high-order system, the design of the controller becomes complicated. This increases the difficulty of debugging in practical applications and also increases the risk of controller oscillation.

[0006] (4) Disturbance observer with proportional-integral control. In order to eliminate steady-state error, this disturbance observer needs to increase the integral gain at high frequencies, which will lead to system instability and poor high-frequency suppression effect. Summary of the Invention

[0007] This invention addresses the problems existing in the prior art by providing a jitter suppression method using a dynamic bandpass filter and a repetitive controller, which can effectively suppress periodic jitter during motor operation within different frequency ranges, thereby ensuring stable motor operation.

[0008] This invention adopts the following technical solution: a jitter suppression method using a dynamic bandpass filter and a repetitive controller, comprising the following steps.

[0009] A. Obtain the encoder position p of the motor, perform differential calculation on the position p, and obtain the motor speed ω;

[0010] B. The steady-state speed is extracted using a mean filter, multiplied by a mechanically related frequency multiplication factor n, and then multiplied by a coefficient K to obtain the pass frequency f of the bandpass filter, thereby dynamically updating the parameters of the bandpass filter and the repetitive controller;

[0011] C. A bandpass filter, obtained by cascading a low-pass filter and a high-pass filter, is used to detect the jitter speed, and ω is obtained. d .

[0012] D. A repetitive controller is used to suppress motor vibration. The setpoint input to the repetitive controller is 0, and the feedback input to the repetitive controller is the motor vibration speed ω. d The output of the repetitive controller is used as the disturbance torque T. dpre ;

[0013] E. The output T of the repetitive controller dpre Input limiter, set the anti-shake intensity t max Using the sway strength t max For the output T of the repetitive controller dpre Amplitude limiting is applied to obtain the jitter suppression torque T. d ;

[0014] F. Input torque command T c The damping torque T d With torque command T c The actual output torque T is obtained by superimposing the results.

[0015] Preferably, in step A, the formula for calculating the motor speed ω is:

[0016]

[0017] Where ΔT is the sampling period at position p.

[0018] Preferably, in step B, the steady-state rotational speed is extracted using a mean filter, multiplied by a mechanically related frequency multiplication factor n, and multiplied by a coefficient K to obtain the pass frequency f of the bandpass filter, thereby dynamically updating the parameters of the bandpass filter and the repetitive controller.

[0019] Preferably, in step C, the motor vibration speed ω is calculated. d The calculation formula is:

[0020] g(n+1) = aω(n+1) + bg(n)

[0021] ω d (n+1)=g(n+1)-g(n)+cω d (n)

[0022]

[0023] c = 1 - 2πfΔT

[0024] Where ΔT is the discrete time, and f is the detected jitter frequency.

[0025] Preferably, in step D, the output of the repeating controller is...

[0026] T opre (n)=K1T opre (nN)+K2ω d (n-N+M)(n=1,2,...)

[0027] In practical applications, K1 is set to 0.9, K2 to 0.4, and N and M vary with f. Preferably, in step E, when T... opre Greater than t max At that time, T d =t max When T opre Less than -t max At that time, T d =-t max Otherwise T d =T opre .

[0028] The beneficial effects of this invention are:

[0029] This invention provides a jitter suppression method employing a dynamic bandpass filter and a repetitive controller. The technique detects the jitter speed using a bandpass filter, the pass frequency of which is calculated from the steady-state motor speed; the higher the motor speed, the higher the bandpass filter frequency. A repetitive controller is used to control the jitter speed, with the control target set to 0. The output of the repetitive controller serves as the periodic disturbance torque. This jitter suppression method can eliminate periodic disturbance torque caused by mechanical or electrical factors. Simultaneously, a frequency multiplication factor is introduced to suppress periodic jitter caused by different mechanical reduction ratios, demonstrating strong versatility. During operation, the disturbance frequency is dynamically adjusted, resulting in strong suppression at different speeds. The introduction of the repetitive controller significantly reduces jitter, enhances system robustness, and makes the load-side operation smoother. Attached Figure Description

[0030] Figure 1 This is a flowchart of the present invention.

[0031] Figure 2 This is a control block diagram of the present invention.

[0032] Figure 3 This is a control block diagram of the repeating controller of the present invention. Detailed Implementation

[0033] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention. The present invention will be described in detail below with reference to the accompanying drawings.

[0034] This embodiment provides a jitter suppression method using a dynamic bandpass filter and a repetitive controller. The calculation process is as follows: Figure 1 As shown, the control block diagram is as follows: Figure 2 As shown, it includes the following steps:

[0035] (1) Obtain the motor speed signal ω.

[0036] The motor speed signal is obtained by differentiating the position value p of the motor encoder.

[0037] Where ΔT is the difference time.

[0038] (2) Shaking speed ω d Testing.

[0039] Most load disturbances and jitter frequencies are directly proportional to motor speed. To suppress jitter frequencies at different speeds, a mean filter is used to extract the steady-state speed, multiply it by a mechanically relevant frequency multiplication factor n, and then by a coefficient K to obtain the pass frequency f of the bandpass filter, thereby dynamically updating the bandpass filter parameters. The bandpass filter is obtained by cascading a low-pass filter and a high-pass filter. The calculation of the low-pass filter is as follows:

[0040] g(n+1) = aω(n+1) + bg(n)

[0041]

[0042] Where ΔT is the discrete time, and f is the detected jitter frequency.

[0043] The high-pass filter is calculated as follows:

[0044] ω d (n+1)=g(n+1)-g(n)+cω d (n)

[0045] Where c = 1 - 2πfΔT.

[0046] (3) Suppression of jitter controller.

[0047] Traditional controllers use PI controllers. However, PI control requires increased integral gain to track periodic signals without steady-state error, which can lead to system instability. Therefore, a repetitive controller is designed to suppress disturbances. The advantage of the repetitive controller is its ability to effectively suppress periodic interference signals and improve the system's anti-interference capability. The setpoint of the repetitive controller is 0.

[0048] Its control structure is as follows: Figure 3 As shown;

[0049] The output of the repetitive controller can be considered as the disturbance torque. The calculation process is as follows:

[0050] T opre (n)=K1T opre (nN)+K2ω d (n-N+M)

[0051] In practical applications, K1 is set to 0.9, K2 to 0.4, and N and M change with the change of f.

[0052] (4) Based on the preset shake suppression intensity t max The output of the repetitive controller is limited to obtain the jitter torque.

[0053] When T dopre Greater than t max At that time, T d =t max ;

[0054] When T dopre Less than -t max At that time, T d =-t max ;

[0055] Otherwise T d =T dpre .

[0056] (5) Finally, the damping torque T d Superimposed on torque command T c In this process, the actual output torque T is obtained.

[0057] T = T d +T c

[0058] This invention provides a jitter suppression method employing a dynamic bandpass filter and a repetitive controller. The technique detects the jitter speed using a bandpass filter, the pass frequency of which is calculated from the steady-state motor speed; the higher the motor speed, the higher the bandpass filter frequency. A repetitive controller is used to control the jitter speed, with the control target set to 0. The output of the repetitive controller serves as the periodic disturbance torque. This jitter suppression method can eliminate periodic disturbance torque caused by mechanical or electrical factors. Simultaneously, a frequency multiplication factor is introduced to suppress periodic jitter caused by different mechanical reduction ratios, demonstrating strong versatility. During operation, the disturbance frequency is dynamically adjusted, resulting in strong suppression at different speeds. The introduction of the repetitive controller significantly reduces jitter, enhances system robustness, and makes the load-side operation smoother.

[0059] This invention achieves jitter suppression by dynamically adjusting the bandpass filter and employing a repetitive controller, and includes the following steps:

[0060] 1. Obtain the encoder position signal of the motor, and perform differential processing on the signal to obtain the motor speed signal;

[0061] 2. The steady-state speed of the motor is extracted using a mean filter, and the pass frequency of the bandpass filter is calculated based on the steady-state speed. The calculation of the pass frequency includes multiplying the steady-state speed by a mechanically related multiplication factor n and a coefficient K, thereby dynamically updating the parameters of the bandpass filter.

[0062] 3. The vibration speed of the motor is detected by using a bandpass filter composed of a cascaded low-pass filter and a high-pass filter. The frequency parameters of the bandpass filter are adjusted in real time according to the change of motor speed.

[0063] 4. A repetitive controller is used to control the detected jitter speed. The target output of the repetitive controller is set to zero, its feedback input is the jitter speed of the motor, and the output result is used as the periodic disturbance torque.

[0064] 5. The output of the repetitive controller is limited. The limiting value is dynamically adjusted according to the preset jitter suppression intensity to avoid system instability caused by excessive suppression, and the jitter suppression torque is obtained.

[0065] 6. The damping torque is superimposed with the torque command to generate the actual output torque signal, which is then applied to motor control to effectively suppress jitter.

[0066] The frequency multiplication factor n is determined based on the reduction ratio of the mechanical system, enabling the bandpass filter to adapt to periodic jitter under different mechanical configurations and possessing versatility. The mean filter is used to extract the steady-state speed of the motor to filter out fluctuations caused by instantaneous disturbances, thereby accurately calculating the pass frequency of the bandpass filter and ensuring that the filter's frequency parameters can be adjusted in real time with changes in motor speed. The repetitive controller includes a delay device and a compensation circuit, which can provide efficient suppression of periodic jitter of the motor at specific frequencies, especially under high-frequency jitter, avoiding the stability problems of traditional PI controllers under high-frequency conditions. The limiting processing includes setting an upper limit and a lower limit. When the output of the repetitive controller exceeds the upper limit, the output result is limited to within the upper limit; when it is below the lower limit, the output result is limited to within the upper limit. The output is limited to a lower limit, effectively preventing system instability caused by excessive suppression. The parameter update frequency of the bandpass filter is dynamically adjusted according to the real-time speed change of the motor, ensuring that the bandpass filter provides the best suppression effect at different motor speeds, especially under rapid speed changes, ensuring the continuity and stability of the jitter suppression effect. The jitter suppression intensity is dynamically adjusted according to the motor's operating state and load characteristics to ensure the best suppression effect under different working environments, while maintaining the overall stability and robustness of the system. The output of the repetitive controller is weighted with the jitter speed signal output by the bandpass filter to enhance the system's response speed to jitter of different frequencies, enabling the motor to maintain smooth operation under various working conditions.

[0067] Example 1:

[0068] In a high-precision CNC machining center, a servo system driven by a permanent magnet synchronous motor is used to control the precise movement of the machining tool. This system requires the tool to follow a predetermined path precisely to ensure machining accuracy. However, due to errors in the servo system's current sensor, coupled with periodic disturbances in the reducer of the mechanical system, the motor's output torque exhibits periodic fluctuations during operation. These fluctuations cause slight deviations in the tool during operation, thus affecting machining accuracy and increasing the scrap rate.

[0069] Traditional solutions to reduce jitter, such as using high-precision current sensors or improving mechanical structures, are effective but costly, and these methods only address specific problems, failing to maintain consistent suppression under varying operating conditions. Furthermore, while notch filters or proportional-integral resonant controllers (PIRC) effectively suppress jitter within a certain frequency range, their effectiveness significantly decreases with changes in tool speed or load, failing to meet the requirements of high-precision machining. Moreover, in high-frequency jitter scenarios, the adjustment of the integral gain in PIRC can easily lead to system instability.

[0070] To address the aforementioned problems, this invention proposes a jitter suppression method based on a dynamic bandpass filter and a repetitive controller. Specifically, in this embodiment, the encoder position signal of the servo motor is first acquired and differentially processed to obtain the real-time motor speed. Since the motor speed constantly changes with the movement of the machining tool, traditional fixed-parameter bandpass filters struggle to adapt to this variation. Therefore, this invention extracts the steady-state motor speed using a mean filter and multiplies this speed by a preset doubling factor n and coefficient K to dynamically calculate the pass frequency f of the bandpass filter. This real-time adjusted filter parameter enables the filter to effectively suppress jitter at different speeds, maintaining a high suppression effect, especially during motor acceleration or deceleration.

[0071] Next, a bandpass filter, composed of a cascaded low-pass filter and a high-pass filter, is used to detect the motor's jitter speed. Unlike traditional methods, the filter frequency of this invention dynamically adjusts with the motor speed, ensuring effective detection and suppression of jitter at different frequencies. Subsequently, the jitter speed signal is input to a repetitive controller. Unlike traditional PI controllers, the repetitive controller has stronger suppression capabilities at specific frequencies, especially under high-frequency jitter conditions, avoiding system instability caused by improper gain adjustment in PI controllers.

[0072] In this embodiment, to prevent system instability caused by excessive suppression, the output of the repeating controller is subjected to amplitude limiting. This amplitude limiting process dynamically adjusts the damping intensity according to the motor operating state, ensuring that the damping torque is always within the acceptable range of the system, thus avoiding the problems of excessive or insufficient suppression that may occur in traditional control methods.

[0073] Finally, the jitter suppression torque is superimposed with the torque command of the servo system to generate the actual output torque signal, which controls the operation of the motor. Through the jitter suppression method of this invention, the servo system of the CNC machining center can maintain stable operation under various complex working conditions (such as tool acceleration, load changes, etc.), significantly reducing machining errors and improving product yield.

[0074] Through the above-described embodiments, the present invention not only solves the problem that traditional jitter suppression methods are ineffective under dynamic conditions, but also significantly improves the robustness and accuracy of the system, providing effective technical support for the field of high-precision CNC machining.

[0075] Example 2:

[0076] In an industrial automated production line, a servo system driven by a permanent magnet synchronous motor (PMSM) is used to control the precise positioning of a robotic arm. Because the production line needs to maintain stable operation at varying speeds, the robotic arm moves frequently with significant speed variations, placing extremely high demands on the accuracy and stability of the servo system. However, traditional PI controllers struggle to effectively suppress the periodic jitter of the robotic arm at high speeds. Especially at high speeds, to eliminate steady-state error, the PI controller typically needs to increase its integral gain, which leads to decreased system stability and poor suppression of high-frequency jitter, easily causing vibration in the robotic arm and affecting the processing accuracy of the products.

[0077] To address the aforementioned problems, this invention proposes a jitter suppression method based on a dynamic bandpass filter and a repetitive controller. First, the real-time motor speed is obtained by differentially processing the position signal p from the motor encoder. Since the motor speed constantly changes with the operating state of the assembly line, traditional fixed-parameter bandpass filters cannot adapt to this dynamic change and struggle to maintain suppression effectiveness under varying operating conditions. Therefore, this invention employs a mean filter to extract the steady-state speed and multiplies it by a mechanically relevant frequency multiplication factor n and a coefficient K to dynamically calculate the pass frequency f of the bandpass filter. This dynamically adjusted filter parameter can adapt to the periodic jitter of the robotic arm at different operating speeds, effectively improving the accuracy of jitter suppression and the robustness of the system.

[0078] The detected jitter speed is transmitted to the repetitive controller via a bandpass filter. The repetitive controller has strong suppression capabilities at specific frequencies, especially in the case of high-frequency jitter, and can avoid the system instability problems caused by improper gain adjustment of traditional PI controllers. The repetitive controller sets the feedback input of the jitter speed signal to zero and uses the output as a periodic disturbance torque, which is directly applied to the servo system, so that the jitter of the robotic arm is effectively controlled.

[0079] To further ensure system stability, this invention incorporates a limiter at the output of the repetitive controller, which limits the output according to a preset jitter suppression intensity. This limiting design effectively prevents system instability caused by excessive suppression, ensuring stable output even at high speeds.

[0080] Ultimately, after the jitter suppression treatment of this invention, the robotic arm can maintain a stable motion trajectory throughout the entire production line operation, and can maintain high processing accuracy even under drastic speed changes. This not only improves product quality and yield, but also significantly reduces equipment wear and maintenance costs, and enhances the efficiency and reliability of the entire system.

[0081] Through the implementation of this invention, the servo system of an industrial automated production line can maintain excellent jitter suppression when dealing with the operational requirements under different working conditions. This invention achieves the following technical effects:

[0082] 1. Enhanced System Versatility: By introducing a frequency multiplication factor, this invention can adapt to periodic jitter caused by different mechanical reduction ratios, greatly improving the versatility of the suppression technology. Regardless of the mechanical configuration, the system can effectively suppress jitter caused by periodic disturbances, avoiding the complex process of recalibrating the system according to different operating conditions in traditional technologies.

[0083] 2. Dynamic Adaptive Jitter Suppression: By monitoring and calculating the motor speed in real time, this invention can dynamically adjust the frequency parameters of the bandpass filter, enabling the filter to adapt to different motor speeds. This dynamic adjustment not only improves the accuracy and stability of jitter suppression but also effectively solves the problem of poor suppression effect of traditional fixed filters under variable speed conditions, ensuring smooth operation of the motor under various speed conditions.

[0084] 3. High-efficiency high-frequency jitter suppression: By replacing the traditional PI controller with a repetitive controller, efficient jitter suppression is achieved at specific frequencies, especially under high-frequency jitter conditions, avoiding the system instability caused by excessive integral gain of the PI controller. The repetitive controller can provide more precise control for the periodic disturbances of the motor, improving the robustness and anti-interference capability of the system.

[0085] 4. Stable and Reliable Output Control: By limiting the output of the repetitive controller, this invention effectively prevents system instability caused by excessive suppression. This design ensures the rationality of the suppression intensity, enabling the system to maintain stable output performance under various operating conditions, avoiding the problems of excessively strong or weak suppression effects that may occur in traditional control methods.

[0086] 5. Real-time Response and Adjustment Capability: This invention can dynamically adjust the parameters of the bandpass filter and repetitive controller according to the real-time operating status of the motor, enabling the system to quickly respond to jitter at different frequencies and ensuring the continuity and stability of the suppression effect. Compared with existing technologies, this invention exhibits superior adaptability and flexibility in dealing with rapid speed change conditions.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the present invention without departing from the scope of the present invention are within the scope of the present invention.

Claims

1. A jitter suppression method employing a dynamic bandpass filter and a repetitive controller, characterized in that, Includes the following steps: A. Obtain the encoder position p of the motor, perform differential calculation on position p, and obtain the motor speed. ; B. The steady-state speed is extracted using a mean filter, multiplied by a mechanically related frequency multiplication factor n, and then multiplied by a coefficient K to obtain the pass frequency f of the bandpass filter, thereby dynamically updating the parameters of the bandpass filter and the repetitive controller; C. A bandpass filter, obtained by cascading a low-pass filter and a high-pass filter, will be used to detect the jitter speed. In step C, the motor vibration speed is calculated. The calculation formula is: in, It is discrete time, and f is the detected chattering frequency; D. A repetitive controller is used to suppress motor vibration. The setpoint input to the repetitive controller is 0, and the feedback input to the repetitive controller is the motor vibration speed. The output of the repetitive controller is used as the disturbance torque. ; E. The output of the repeater controller Input limiter, set the image stabilization intensity Utilizing the intensity of shake reduction Output of the repetitive controller Amplitude limiting is applied to obtain the jitter suppression torque. ; F. Input torque command , will dampen torque With torque command Superimposed, the actual output torque is obtained. .

2. The jitter suppression method using a dynamic bandpass filter and a repetitive controller according to claim 1, characterized in that: In step A, the motor speed The calculation formula is: ，（n=1，2，...） in, Let p be the sampling period at position p.

3. The jitter suppression method using a dynamic bandpass filter and a repetitive controller according to claim 1, characterized in that: In step B, the steady-state speed is extracted using a mean filter, multiplied by a mechanically related frequency multiplication factor n, and then multiplied by a coefficient K to obtain the pass frequency f of the bandpass filter, thereby dynamically updating the parameters of the bandpass filter and the repetitive controller.

4. The jitter suppression method using a dynamic bandpass filter and a repetitive controller according to claim 1, characterized in that: In step D, the output of the repeat controller is... Take 0.9, When the value is 0.4, N and M change dynamically with the change of f.

5. The jitter suppression method using a dynamic bandpass filter and a repetitive controller according to claim 1, characterized in that: In step E, when Greater than hour, = ;when Less than hour, = ;otherwise = .

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