Adaptive controller for overcoming periodic error in servo motor rotation speed control

Abstract

Disclosed in the present invention is an adaptive controller for overcoming a periodic error in servo motor rotation speed control. A controller and a controlled object motor are used to form a servo control inner-layer current loop, then a speed regulator forms a typical speed feedback control, and a harmonic compensator is used as an outer control loop to be attached to a typical servo control loop and used for compensating for repeated disturbance on a motor rotor angular position domain; and the harmonic compensator maps a measured rotation speed error and a current rotor angle to an angular velocity error in the angular position domain, a harmonic component estimation is obtained in the angular position domain, and then the amplitude of a corresponding harmonic compensation component is obtained by means of an adaptive regulator. The present invention allows for compensation for periodic disturbance related to the rotor angle of a servo motor during the motion of the servo motor and improve rotation speed control precision.

Description

An adaptive controller to overcome periodic error in servo motor speed control Technical Field

[0001] The present invention relates to a servo motor speed controller, in particular to an adaptive controller used in the servo motor speed controller and capable of overcoming periodic errors in the servo motor speed control. Background Art

[0002] Servo motor speed controllers are commonly used in automation equipment, such as machine tool control, drones, unmanned vessels, and new energy vehicles. In these automation devices, the most fundamental control unit for motion control of complex mechanical structures is a servo motor speed controller, which controls the rotational motion of the servo motor. Due to inherent factors such as cogging forces, non-uniform magnetic field distribution, and mechanical friction, servo motor rotation can introduce periodic errors in the motor's rotor position domain. This affects the control accuracy of the servo motor speed controller, ultimately impacting the product's control precision and stability. Technical issues

[0003] The present invention aims to solve the problem that the existing servo motor speed controller has periodic errors in speed control, resulting in insufficient control accuracy, which ultimately affects the control accuracy and stability of the product. The present invention provides an adaptive controller that can compensate for the periodic disturbances related to the servo motor rotor angle that exist during the movement of the servo motor, improve the accuracy of speed control, and overcome the periodic errors in the servo motor speed control. Technical Solutions

[0004] The specific technical solution adopted by the present invention to solve the above technical problems is: an adaptive controller for overcoming the periodic error in the speed control of a servo motor, characterized in that: a controller is used and the controlled object motor The inner current loop of the servo control is formed, and then the speed regulator This constitutes a typical speed loop feedback control. The harmonic compensator maps the measured speed error and the current rotor angle to an angular velocity error in the angular position domain, obtaining an estimate of the harmonic components in the angular position domain. This is then used by the adaptive regulator to determine the amplitude of the corresponding harmonic compensation component. This compensates for periodic disturbances related to the servo motor's rotor angle during servo motor motion, improving speed control accuracy.

[0005] Preferably, the The harmonic compensator adopts the following control algorithm steps in sequence:

[0006] F1. Discretization of angular position domain;

[0007] F2. Time domain mapping angular position domain;

[0008] F3. Calculation of harmonic components in the angular position domain;

[0009] F4. Average of angular position domain;

[0010] F5. Parameter adaptive adjustment;

[0011] F6. Calculate Harmonic compensation amount at the sampling moment;

[0012] F7. Harmonic compensator parameter adaptive gain design;

[0013] The design results obtained in the above step F7 are input into the above step F5 for parameter adaptive adjustment.

[0014] Preferably, in the above step F1, the harmonic compensation algorithm is Discrete realization on the domain, domain Discrete Equally divided, with intervals of , so the fundamental period of the motor angular velocity error in the angular position domain is . The value of depends on the highest harmonic to be compensated and the resolution within one cycle. For example, to compensate for the highest 32nd harmonic, a resolution of 8 points is required for one cycle of the harmonic. Take 256, is the motor rotor angular position domain, is pi.

[0015] Preferably, in the above-mentioned step F2, Sampling time obtained 、 and , the mapping from time domain to angular position domain is completed through the following formula,

[0016] ;

[0017] ;

[0018] in Indicates rounding. is the motor rotor angular position domain coordinate, The number of subdivision points of the motor rotor angular position domain, the value is ≥ 256, is the motor angular velocity error in the rotor angular position domain, Sampling time .

[0019] Preferably, in the above step F3, the calculation formula for the harmonic component in the angular position domain is:

[0020] ;

[0021] ;

[0022] Assuming there is no harmonic compensator arrive The transfer function is ,but

[0023] ;

[0024] in It's about controlling the beat. is the motor rotor angular position domain coordinate, The number of points in the motor rotor angular position domain is 256, Transfer function At the harmonic frequency Phase; For The angular velocity error at the sampling moment is in the angular position domain. The amplitude of the harmonic sine component is updated. For The angular velocity error at the sampling moment is in the angular position domain. The amplitude of the harmonic cosine component is updated. is the motor angular velocity error in the motor rotor angular position domain, Sampling time , for Harmonic phase compensation value, is the motor rotor angular position domain coordinate, : Current loop control object.

[0025] Preferably, in the above step F4, the calculation formula used for averaging over the angular position domain is:

[0026] ;

[0027] ;

[0028] in For the angular position domain Harmonic compensation sine component amplitude, For the angular position domain Harmonic compensation cosine component amplitude, The number of points in the motor rotor angular position domain is 256.

[0029] Preferably, in the above step F5, the harmonic components in the rotational speed error are averaged in the angular position domain, and the amplitude of the harmonic compensation is adjusted and updated as follows:

[0030] ;

[0031] ;

[0032] in is the number of updates, is the adaptive adjustment gain. For the angular position domain Harmonic compensation sine component amplitude, For the angular position domain The amplitude of the cosine component of harmonic compensation. The update cycle of the above parameters is the time required for the motor to rotate one circle. The faster the motor speed, the shorter the update cycle. Therefore, when the motor speed changes, the adaptive adjustment is a time-varying control system in the time domain.

[0033] Preferably, in the above step F6, calculate The calculation formula used for harmonic compensation at the sampling time is:

[0034] ;

[0035] in for The compensation output of the harmonic compensator, For the angular position domain Harmonic compensation sine component amplitude, For the angular position domain Harmonic compensation cosine component amplitude, The number of subdivision points of the motor rotor angular position domain, the value is ≥ 256. Beneficial effects

[0036] The beneficial effect of the present invention is that it can compensate for the periodic disturbance related to the servo motor rotor angle that exists during the movement of the servo motor, thereby improving the accuracy of speed control. The main innovations and advantages of the present invention include: (1) converting the periodic disturbance in the time domain into the periodic disturbance in the motor rotor angle position domain; (2) implementing an adaptive compensation controller in the motor rotor angle position domain to compensate for the periodic disturbance, thereby ensuring that the compensation control algorithm can effectively compensate for the periodic disturbance through adaptive adjustment at different motor speeds; (3) the main multiple harmonic components of the periodic disturbance can be selected for compensation. (4) in the adaptive parameter adjustment, the robustness of the algorithm is improved by averaging the parameters in the rotor angle position domain, and when multiple main harmonic components in the compensation disturbance are selected, the stability of the entire control system is not affected. The present invention designs an adaptive repetitive learning compensation controller based on vector control technology to overcome the periodic error in the servo motor speed control and achieve high-precision speed control. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a schematic diagram of the overall functional block diagram of the servo control application of an adaptive controller for overcoming periodic errors in servo motor speed control according to the present invention.

[0038] FIG2 is a schematic diagram of the rotor angular velocity in the rotor angular position domain measured multiple times by an adaptive controller for overcoming periodic errors in servo motor speed control under constant load and constant torque current drive according to the present invention.

[0039] FIG3 shows an adaptive controller for overcoming periodic errors in servo motor speed control without a harmonic compensator. arrive The transfer function is , and the periodic torque disturbance Equivalent to torque current disturbance Schematic diagram of the equivalent block diagram.

[0040] FIG4 is an adaptive controller of the present invention that overcomes the periodic error in the servo motor speed control in the position domain average Schematic diagram of the equivalent block diagram of harmonic compensator position domain harmonic component regulation.

[0041] FIG5 is a schematic diagram of the experimental results of the real-time speed time domain waveform of an adaptive controller for overcoming periodic errors in servo motor speed control according to the present invention when the speed of a 400W motor is set to 1500RPM when the motor is unloaded.

[0042] FIG6 is a schematic diagram of the power spectrum experimental results of the speed error before and after compensation of an adaptive controller for overcoming periodic errors in servo motor speed control of the present invention when the speed of a 400W motor is set to 1500RPM with no load.

[0043] FIG7 shows an adaptive controller for overcoming periodic errors in servo motor speed control according to the present invention. Flowchart of the control algorithm used in the harmonic compensator. Best Mode for Carrying Out the Invention

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] In the embodiments shown in FIG1 , FIG2 , FIG4 and FIG7 , an adaptive controller for overcoming periodic errors in servo motor speed control is provided. FIG1 shows a servo control block diagram with a current loop and a speed loop, and FIG2 shows a servo control block diagram with a current loop and a speed loop. The block diagram of the harmonic compensation controller is shown in Figure 1. The compensation of other harmonic orders is similar. In practical applications, multiple main harmonic components can be selectively compensated according to the actual situation. and the controlled object motor The inner current loop of the servo control is formed, and then the speed regulator In a typical speed loop feedback control, the harmonic compensator first maps the measured speed error and the rotor angle at that time to the angular velocity error in the angular position domain, obtains the harmonic component estimate in the angular position domain, and then obtains the amplitude of the corresponding harmonic compensation component through the adaptive regulator. Due to factors such as cogging force, non-uniform distribution of magnetic pole magnetic field and mechanical friction, when the servo motor rotates, the torque disturbance The main time-varying component of the motor shows repeatability in the rotor angular position domain; Figure 2 is the rotor angular velocity in the rotor angular position domain measured under constant torque current drive in the no-load state of the motor. It can be seen that the speed change and position domain have a strong correlation, and the speed disturbance is mainly caused by the torque disturbance. This indirectly confirms the repeated torque disturbance in the motor rotor angular position domain. . Repeated torque disturbance in the motor rotor angular position domain Generally, it is composed of several major harmonics and fundamental components. The purpose of the compensation controller is to compensate for those major harmonics / fundamental components, thereby achieving high-precision speed control. Second The specific internal structure of the harmonic compensator, other order harmonic compensation (see the mth order in Figure 1) Harmonic compensators) and so on. In practical applications, the main harmonic components can be selectively compensated according to the actual situation. Harmonic compensators include first harmonic compensators... Harmonic compensator... A combination of multiple arbitrary harmonic compensators of the harmonic compensator. Harmonic compensators and Harmonic compensator as an example, respectively represents the corresponding " "sequence" "Harmonic compensator at subharmonic order.

[0046] In servo motor motion control, due to factors such as cogging forces, non-uniform distribution of the magnetic pole field, and mechanical friction, the primary components of torque disturbances exhibit repetitive behavior in the rotor's angular position domain during servo motor rotation. Figure 2 shows that speed changes are repetitive in the rotor's angular position domain, while rotor speed changes are primarily caused by torque disturbances. Consequently, repetitive disturbances occur in the rotor's angular position domain. These repetitive disturbances are generally composed of several major harmonic components. The purpose of the compensation controller is to compensate for these major harmonic components, thereby achieving high-precision speed control.

[0047] The parameters and related Chinese definitions appearing in Figure 1 are as follows:

[0048] : Current loop controller;

[0049] : Current loop control object;

[0050] : Current loop torque current;

[0051] : Current loop torque reference current;

[0052] : torque constant;

[0053] : moment of inertia;

[0054] : Laplace operator;

[0055] : Motor rotor angular velocity;

[0056] : Motor rotor angular position domain;

[0057] : Motor reference angular velocity;

[0058] : Motor angular velocity error;

[0059] : The number of subdivision points of the motor rotor angular position domain, value 256;

[0060] : Motor rotor angular position domain coordinates, ;

[0061] : Motor angular velocity error in the motor rotor angular position domain, Sampling time ;

[0062] :Speed ​​loop controller;

[0063] : Harmonic compensator parameter adaptive gain;

[0064] : Harmonic phase compensation value;

[0065] :exist The angular velocity error at the sampling moment is in the angular position domain. The amplitude of the harmonic sine component is updated;

[0066] :exist The angular velocity error at the sampling moment is in the angular position domain. The amplitude of harmonic cosine components is updated;

[0067] :Angular position domain Harmonic compensation sine component amplitude;

[0068] :Angular position domain Harmonic compensation cosine component amplitude;

[0069] : Compensation output of harmonic compensator;

[0070] : Compensation output of harmonic compensator;

[0071] : total output of the compensator;

[0072] : Periodic disturbance in angular position domain;

[0073] : Assuming there is no harmonic compensator arrive The transfer function of

[0074] The algorithm implementation steps shown in Figures 1 and 7 are as follows:

[0075] Periodic disturbance in angular position domain Reflected in the angular position domain angular velocity error By extracting The corresponding harmonic components in the system are used as feedback to automatically adjust the amplitude and phase of the injected harmonics to compensate for the disturbance. The corresponding harmonic components in the velocity error The wave component converges to 0. Without loss of generality, Taking the harmonic compensator as an example, the following algorithm implementation steps are given:

[0076] F1. Angular position domain discretization 01:

[0077] Harmonic compensation algorithm in Discrete realization on the domain, domain Discrete Equally divided, with intervals of , so the fundamental period of the motor angular velocity error in the angular position domain is . The value of depends on the highest harmonic to be compensated and the resolution within one cycle. For example, to compensate for the highest 32nd harmonic, a resolution of 8 points is required for one cycle of the harmonic. Take 256, is the motor rotor angular position domain, is pi.

[0078] F2. Time domain mapping angular position domain 02:

[0079] exist Sampling time obtained 、 and , the mapping from time domain to angular position domain is completed through the following formula,

[0080] ;

[0081] ;

[0082] in Indicates rounding. is the motor rotor angular position domain coordinate.

[0083] F3. Calculation of harmonic components in the angular position domain 03:

[0084] ;

[0085] ;

[0086] In Figure 1, it is assumed that there is no harmonic compensator. arrive The transfer function is ,but

[0087] ;

[0088] in It's about controlling the beat. Transfer function At the harmonic frequency phase.

[0089] F4. Average 0.4 on angular position domain:

[0090] ;

[0091] ;

[0092] F5. Parameter adaptive adjustment 05:

[0093] The harmonic components in the speed error are averaged in the angular position domain, and the amplitude of the harmonic compensation is adjusted and updated as follows:

[0094] ;

[0095] ;

[0096] in is the number of updates, is the adaptive adjustment gain. The update cycle of the above parameters is the time it takes for the motor to complete one revolution. The faster the motor speed, the shorter the update cycle. Therefore, when the motor speed changes, the adaptive adjustment is a time-varying control system in the time domain.

[0097] F6. Calculate Harmonic compensation amount at sampling time 06:

[0098] ;

[0099] F7. Harmonic compensator parameter adaptive gain Design 07:

[0100] In Figure 1, without loss of generality, it is assumed that there is no harmonic compensator. arrive The transfer function is , and the periodic torque disturbance Equivalent to torque current disturbance ;

[0101] The design results obtained in the above step F7 are input into the above step F5 for parameter adaptive adjustment.

[0102] As shown in Figure 3, the outer loop harmonic compensator Harmonic compensator parameter adaptive gain The motor is updated once per revolution. If the speed is constant at 3000RPM, the control frequency is 50Hz, while the speed loop control frequency is generally greater than 5kHz. In this case, the outer loop harmonic compensator can be analyzed and designed under the condition of the inner loop speed loop being in steady state. Harmonic compensator parameter adaptive gain .

[0103] Without loss of generality, harmonic For example:

[0104] ;

[0105] ;

[0106] ;

[0107] ;

[0108] ;

[0109] ;

[0110] From the above, it can be seen that the average in the rotor angular position domain is equivalent to doing a DFFT in the rotor angular position domain. Before the parameters of the outer harmonic compensation loop are updated, have gradually converged to Output the amplitude of the corresponding harmonic component.

[0111] Therefore, from middle From the perspective of transmission in the entire control loop, The adaptive adjustment of parameters is equivalent to that shown in Figure 4. The amplitude of the sine component of the compensation signal in the rotor angular position domain is arrive The transfer function is as follows:

[0112] ;

[0113] yes In frequency The amplitude of , compensation component amplitude It will converge to Taking into account the convergence speed of parameters and the influence of noise, The choice satisfies The fastest convergence.

[0114] Experimental results:

[0115] Figures 5 and 6 show the experimental results of a 400W motor with no load and a set speed of 1500 RPM. The base frequency at this time is 1500 / 60 = 25 Hz.

[0116] Figure 5 shows the real-time velocity waveform (before compensation: solid line; after compensation: dashed line). After compensation, the velocity accuracy is significantly improved, and the velocity distribution variance is reduced from 30.9 rpm to 18 rpm.

[0117] Figure 6 shows the power spectrum of the velocity error before and after compensation. The uncompensated error (solid line) contains significant harmonic components at the 4th (100 Hz), 8th (200 Hz), and 24th (600 Hz). By selectively compensating for these three harmonics, the compensated power spectrum (dashed line) achieves a highly significant compensation effect, essentially eliminating the three harmonic components while maintaining the amplification of other frequency components.

[0118] The above content and structure describe the basic principles, main features, and advantages of the product of the present invention, which should be understood by those skilled in the art. The above examples and description are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications are intended to be within the scope of the invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. An adaptive controller for overcoming periodic errors in servo motor speed control, characterized in that: Using controller and the controlled object motor The inner current loop of the servo control is formed, and then the speed regulator A typical speed loop feedback control is formed. The harmonic compensator maps the measured speed error and the rotor angle at that time to the angular velocity error in the angular position domain, obtains the harmonic component estimate in the angular position domain, and thereby obtains the amplitude of the corresponding harmonic compensation component through the adaptive regulator.

2. The adaptive controller for overcoming periodic error in servo motor speed control according to claim 1, characterized in that: The The harmonic compensator adopts the following control algorithm steps in sequence: F1. Discretization of angular position domain; F2. Time domain maps to angular position domain; F3. Calculation of harmonic components in the angular position domain; F4. Average of angular position domain; F5. Parameter adaptive adjustment; F6. Calculate Harmonic compensation amount at sampling time; F7. Harmonic compensator parameter adaptive gain design; The design result obtained in the above step F7 is input into the above step F5 for parameter adaptive adjustment.

3. The adaptive controller for overcoming periodic error in servo motor speed control according to claim 2, characterized in that: In the above step F1, the harmonic compensation algorithm is Discrete realization on the domain, domain Discretize into N equal parts, with intervals of , so the fundamental period of the motor angular velocity error in the angular position domain is ; The value of depends on the highest harmonic to be compensated and the resolution within one cycle. For example, to compensate for the highest 32nd harmonic, a resolution of 8 points is required for one harmonic cycle, so N is 256. is the motor rotor angular position domain, is the ratio of pi.

4. The adaptive controller for overcoming periodic error in servo motor speed control according to claim 2, characterized in that: In the above step F2, Sampling time obtained , and , the mapping from time domain to angular position domain is completed by the following formula, ； ； in Indicates rounding. is the motor rotor angular position domain coordinate, The number of subdivision points of the motor rotor angular position domain, the value is ≥256, is the motor angular velocity error in the rotor angular position domain, Sampling time 。 5. The adaptive controller for overcoming periodic error in servo motor speed control according to claim 2, characterized in that: In the above step F3, the calculation formula for the harmonic component in the angular position domain is: ； ； Assuming there is no harmonic compensator arrive The transfer function is ,but ； in It's to control the beat. The number of subdivision points of the motor rotor angular position domain, value 256， is the transfer function At the harmonic frequency The phase of For The angular velocity error at the sampling time is in the angular position domain. The amplitude of the harmonic sine component is updated. For The angular velocity error at the sampling time is in the angular position domain. The amplitude of the harmonic cosine component is updated. is the motor angular velocity error in the motor rotor angular position domain, Sampling time ， for Harmonic phase compensation value, is the motor rotor angular position domain coordinate, : Current loop control object.

6. The adaptive controller for overcoming periodic error in servo motor speed control according to claim 2, characterized in that: In the above step F4, the calculation formula used for averaging in the angular position domain is: ； ； in For the angular position domain Harmonic compensation sine component amplitude, For the angular position domain Harmonic compensation cosine component amplitude, is the motor rotor angular position domain coordinate, The number of subdivision points of the motor rotor angular position domain, value 256。 7. The adaptive controller for overcoming periodic error in servo motor speed control according to claim 2, characterized in that: In the above step F5, the harmonic components in the speed error are averaged in the angular position domain, and the amplitude of the harmonic compensation is adjusted and updated as follows: ； ； in is the number of updates, is the adaptive adjustment gain, For the angular position domain Harmonic compensation sine component amplitude, For the angular position domain The amplitude of the cosine component of harmonic compensation. The update cycle of the above parameters is the time required for the motor to rotate one circle. The faster the motor speed, the shorter the update cycle. Therefore, when the motor speed changes, the adaptive adjustment is a time-varying control system in the time domain.

8. The adaptive controller for overcoming periodic error in servo motor speed control according to claim 2, characterized in that: In step F6 above, calculate The calculation formula used for harmonic compensation at the sampling time is: ； in for The compensation output of the harmonic compensator, For the angular position domain Harmonic compensation sine component amplitude, For the angular position domain Harmonic compensation cosine component amplitude, is the motor rotor angular position domain coordinate, The number of subdivision points of the motor rotor angular position domain, the value is ≥256.

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