Variable load self-adaptive control method for high-speed rotary table

Abstract

The invention discloses a high-speed turntable variable load adaptive control method, which is based on a closed-loop control mode, realizes adaptive regulation and control of a microprocessor on the rotating speed and the position of a servo motor by combining a fuzzy PID (Proportion Integration Differentiation) control algorithm, reduces the regulation response time and errors of a high-speed turntable, and improves the operation stability of a turntable system. The rotation angle of the high-speed rotary table is fed back to a microprocessor by a displacement sensor to form a closed-loop control system, and an improved gravity center Lagrange interpolation-Fourier harmonic synthesis displacement sensor error compensation model is established, so that the high-speed rotary table can still obtain a high-precision displacement measurement result in a variable-load processing working environment; a software operating system is designed to control and realize multi-task operation such as start-stop, initialization, instruction import and the like of the turntable, and the real-time performance and the detectability of the high-speed turntable system are improved. The method can be used for self-adaptive control under the condition of a variable-load high-speed turntable, and has the characteristics of high precision, fast response and good robustness.

Description

Technical Field

[0001] The invention belongs to the field of electromechanical system control design, and in particular relates to a high-speed turntable variable load adaptive control method. Background Art

[0002] High-end equipment such as precision instruments and machine tools play an important role in modern manufacturing. As an important component of precision measuring instruments and precision processing equipment, high-speed turntables are widely used in aircraft design and development, aerospace, inertial navigation testing, and the manufacture of advanced weapon systems. The operating performance of high-speed turntables under variable load conditions will directly affect the use effect and processing quality of high-precision systems. Therefore, it is of great significance to increase research on variable load high-speed turntable control methods.

[0003] High-performance turntable control systems rely on reliable motor hardware, precision measuring devices, reasonable hardware design and control strategies. After the hardware is determined, adopting better control algorithms and control mechanisms is an effective way to improve system accuracy. At present, industrial turntable control systems mainly use algorithms such as PID control, compound control and Smith prediction. These traditional algorithms are based on mature theories. By establishing accurate mathematical models and compensating interference signals, control links are designed to improve control accuracy and performance. However, in practice, turntables work in complex working environments and are affected by nonlinear factors such as motor friction, electromagnetic transition, and torque coupling. In addition, changes in the turntable load will cause changes in the moment of inertia, making it difficult to establish an accurate model and affecting the control effect. In order to adapt to internal and external disturbances and parameter changes in the adaptive system, advanced technologies such as neural networks and fuzzy control are gradually applied to high-speed turntable control systems. Servo motors are used instead of stepper motors as drive devices to solve motor speed and subdivision problems. Detection elements are introduced to form a closed-loop detection system to provide position information to ensure rotation accuracy. With the rapid development of precision manufacturing and posture detection, the requirements for control feedback of turntable position, angle, etc. are gradually increasing. Error compensation is one of the important measures to improve sensing accuracy. Common methods include using genetic algorithms, error fitting, deep training, etc. to establish error compensation models, but they all ignore the misalignment error introduced by the sensor during continuous dynamic detection, which affects the error compensation effect of the sampling period and leads to the lag of turntable feedback control. Therefore, it is of great practical value to develop a high-speed turntable variable load adaptive control method with high accuracy, fast response, strong robustness and wide adaptability. Summary of the invention

[0004] The present invention proposes a variable load adaptive control method for a high-speed turntable, which is based on a closed-loop control method combined with a fuzzy PID control algorithm and a displacement sensor error compensation model to achieve high-precision, fast response, strong robustness and real-time adaptive control of the high-speed turntable under disturbance environments and variable load conditions.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: A high-speed turntable variable load adaptive control method comprises the following steps: Step 1: Get the initial state of the high-speed turntable and controller, and send closed-loop instructions for the required position and speed; Step 2: Establish the motor transfer function of the turntable drive servo system; Step 3: The displacement sensor detects the angular displacement of the high-speed turntable and obtains the interpolation function value of each data point according to the interpolation principle; Step 4: Reconstruct the interpolation curve in step 3 to obtain the amplitude and phase information of each order harmonic and construct the sensor error compensation model; Step 5: Set the turntable closed-loop control process so that the transfer function remains stable after parameter transformation; Step 6: Compare the actual speed of the high-speed turntable motor obtained in step 4 with the expected speed, and input the error e and error change rate to fuzzy PID controller; Step 7: Detect turntable error and output fuzzy control self-adjustment parameters Used to modify control parameters; Step 8: Adjust the driving state of the servo motor according to the PID control parameters given in step 7, thereby achieving continuous adaptive control of the high-speed turntable speed.

[0006] Furthermore, in step 1, the host computer obtains basic information related to the high-speed turntable and servo motor, including speed limit, torque limit and safe operation parameters, performs initialization processes such as checking hardware connections, calibrating sensors, and setting initial parameters, and sends closed-loop control instructions of the required position and speed to the actuator according to the requirements of the machine tool processing workpiece, and starts the high-speed turntable via the servo amplifier driving the motor.

[0007] Furthermore, step 2 establishes the motor transfer function of the turntable drive servo system, which is specifically implemented as follows: Assuming that the mass and shape of each component in the turntable system are uniform, the friction force in the system is As a function of the actual position and speed, the torque balance equation of the servo system is: (1) in, is the moment of inertia, is the actual angular displacement of the system, is the system speed, is the output torque, For system load, set is the theoretical angular displacement of the system, then the motor transfer function Can be considered as and If the ratio is the Laplace variable, is the motor reduction ratio, and the changed motor transfer function is: (2) The changed motor transfer function is used as the basis for subsequent feedback control.

[0008] Furthermore, in step 3, the displacement sensor detects the angular displacement of the high-speed turntable, and obtains the interpolation function value of each node of the data according to the interpolation principle, which is specifically implemented as follows: The improved center-of-gravity Lagrange interpolation method is used to calculate the values ​​near the discrete displacement angle points of the high-speed turntable recorded by the displacement sensor; K+1 nodes are taken on the data interval [a, b] , then the displacement angle value of the corresponding node for: (3) According to formula (4), the Lagrange basic polynomial is defined as and center of gravity , according to the improved Lagrange interpolation method, the values ​​near the displacement points of finite nodes (K+1 nodes) are calculated, that is, the polynomial is interpolated near the endpoints of the data interval to deal with the problem of displacement curve oscillation caused by load changes, and the displacement angle value can be obtained for: (4) Thus, the displacement sensor position information and the corresponding sensor angle information are obtained.

[0009] Furthermore, step 4 reconstructs the interpolation curve of step 3 to obtain the amplitude and phase information of each order harmonic and constructs the sensor error compensation model, which is specifically implemented as follows: Based on Fourier expansion and convergence theorem, the interpolation curve is reconstructed into a finite sine wave according to the relationship between phase, amplitude and frequency, and the sensor displacement error value is decomposed. for: (5) (6) Where k is the harmonic order, is the constant term coefficient, is the cosine wave coefficient, is the error value sine wave frequency information, is the harmonic amplitude, and the phase can be obtained by calculating the inverse tangent of the ratio of the displacement error harmonic coefficients; according to the sampling theorem, k+1 nodes are extracted within the curve period, and the maximum number of fitted periodic terms is set to n(k+1), then the coefficient value of the Fourier series fitting error function is inversely calculated as: (7) Thus, the sine and cosine harmonic coefficients of each order of the interpolation curve are obtained. The harmonics whose values ​​are greater than the set threshold and whose influence on the error result exceeds the set error threshold, namely the 0th, 2nd and 4th order harmonics, realize the compensation reconstruction of the displacement sensor error data.

[0010] Furthermore, the step 5 sets the turntable closed-loop control process so that the transfer function remains stable after the parameter transformation, which is specifically implemented as follows: Assuming R is the input signal, C is the output signal, and N is the interference signal related to the system friction and variable load, For the front control link, is the controlled object, H is the transfer function of the closed-loop control system, and according to the system signal superposition principle, the total output signal can be obtained as follows: (8) The interpolation of the theoretical angular displacement and the actual angular displacement of the calculation system can obtain the system error: , error change rate , and Respectively and The first derivative of .

[0011] Furthermore, step 6 compares the actual speed of the high-speed turntable motor obtained in step 4 with the expected speed, and inputs the system error e and the error change rate To the fuzzy controller, the specific implementation is as follows: The fuzzy controller uses the output to perform online correction on the parameters of the PID controller to achieve the desired control effect. If the system error e and the error change rate As the input variable of the fuzzy PID controller, the proportional coefficient is set according to the definition domain of the quantization factor and the proportional factor. The fuzzy domain is {-3,-2,-1,0,1,2,3}, and the integral coefficient is set and the differential coefficient The fuzzy domain is {-0.3, -0.2, -0.1, 0, 0.1, 0.2, 0.3}, the fuzzy set describing the input and output is {NB, NM, NS, Z, PS, PM, PB}, and the membership function of the fuzzy controller is a combination of trigonometric functions and Gaussian membership functions commonly used in engineering.

[0012] Furthermore, the step 7 is to perform reasoning based on the fuzzy control rules of the parameters combined with the minimum operation algorithm to obtain the fuzzy result ,in Represents error e and error change rate After the intermediate value of fuzzy inference, it is defuzzified based on the centroid method to obtain , taking the proportional coefficient as an example, we can get: (9) in, The solution and same; Based on the adjustment parameters obtained by the fuzzy controller, the original control parameters of the PID controller are corrected to obtain , , and Indicates the PID parameters obtained in the previous calibration. Continuously adjust the response rate, oscillation amplitude and stabilization time of the variable load turntable system.

[0013] Furthermore, the step 8 transmits the corrected PID parameter signal to the servo motor driver, adjusts the servo motor output current ratio to the turntable system torque, speed and position, and realizes continuous adaptive control of the high-speed turntable speed.

[0014] The beneficial effects of the present invention compared to the prior art are: First, the present invention proposes to perform error compensation on the output angular displacement of the displacement sensor to avoid control lag caused by misalignment error during continuous dynamic detection, such as Figure 4 As shown, this method can better control the angular displacement error when the turntable rotates at high speed; Second, the present invention is based on fuzzy PID servo control, which effectively avoids the problem of being unable to establish an accurate servo control system mathematical model in a disturbed environment and a complex working environment with variable loads, such as Figure 6 , 7 As shown in Figure 8, this method has better rapid response, anti-interference and robust performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention is a flow chart of a variable load adaptive control method for a high-speed turntable.

[0016] Figure 2 It is the structural functional block diagram of the high-speed turntable control system.

[0017] Figure 3 It is a mathematical model diagram of the high-speed turntable adaptive control method.

[0018] Figure 4 It is a comparison diagram of the angular displacement measurement errors of the present invention and the existing method under high-speed rotation.

[0019] Figure 5 It is a membership function distribution curve diagram that combines the error e trigonometric function and the Gaussian membership function.

[0020] Figure 6 It is a comparison diagram of the fast responsiveness angular velocity of the present invention and the existing method.

[0021] Figure 7 It is a comparison diagram of the anti-interference angular velocity of the present invention and the existing method.

[0022] Figure 8 It is a comparison diagram of the angular velocity of the gradual sinusoidal signal following robustness of the present invention and the existing method. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0024] The embodiment of the present invention relates to a variable load adaptive control method for a high-speed turntable, which realizes high-precision, fast-response, and strong robustness adaptive control of a high-speed turntable in a disturbance environment and a variable load working environment.

[0025] like Figure 1 As shown, a high-speed turntable variable load adaptive control method, the method should include the following steps: Step 1: Get the initial status of the high-speed turntable and the controller, and send the closed-loop instructions for the required position and speed. The specific operation is that the host computer obtains the basic information related to the high-speed turntable and servo motor, including speed limit, torque limit and safe operation parameters, and performs initialization processes such as checking hardware connections, calibrating sensors, and setting initial parameters. According to the requirements of the machine tool processing workpiece, the closed-loop control instructions of the required position and speed are sent to the actuator, and the high-speed turntable is started through the servo amplifier driving the motor.

[0026] Step 2: Establish the motor transfer function of the turntable drive servo system. The specific implementation is as follows: Assume that the mass and shape of each component in the turntable system are uniform, and the friction force in the system is As a function of the actual position and speed, the torque balance equation of the servo system is: (1) in, is the moment of inertia, is the actual angular displacement of the system, is the system speed, is the output torque, For system load, set is the theoretical angular displacement of the system, then the motor transfer function G(s) can be regarded as The ratio of, if s is the Laplace variable, is the motor reduction ratio, and the motor function after changing the formula is: (2) The changed motor transfer function is used as the basis for subsequent feedback control.

[0027] Step 3: The displacement sensor detects the angular displacement of the high-speed turntable, and obtains the interpolation function value of each node of the data according to the interpolation principle. Specifically, the improved center of gravity Lagrange interpolation method is used to calculate the value near the discrete displacement angle error point of the high-speed turntable recorded by the displacement sensor; select K+1 nodes on the data interval [a, b] , then the displacement angle value of the corresponding node for: (3) According to formula (4), the Lagrange basic polynomial is defined as and center of gravity , the values ​​near the finite nodes (K+1 nodes) are calculated based on the improved Lagrange interpolation method, that is, the interpolation polynomial near the endpoints of the data interval is used to deal with the problem of displacement error curve oscillation caused by load changes, and the displacement angle value can be obtained for: (4) Thus, the displacement sensor position information and the corresponding sensor angle information are obtained.

[0028] Step 4: Reconstruct the interpolation curve in step 3 to obtain the amplitude and phase information of each order harmonic, and construct the sensor error compensation model. Specifically, based on Fourier expansion and convergence theorem, the error curve is reconstructed into a finite sine wave according to the relationship between phase, amplitude and frequency, and the decomposed sensor displacement error value is: (5) (6) Where k is the harmonic order, is the constant term coefficient, is the cosine wave coefficient, is the error value sine wave frequency information, is the harmonic amplitude, and the phase can be obtained by calculating the inverse tangent of the ratio of the displacement error harmonic coefficients; according to the sampling theorem, k+1 nodes are extracted within the curve period, and the maximum number of fitted periodic terms is set to n(k+1), then the coefficient value of the Fourier series fitting error function is inversely calculated as: (7) Thus, the sine and cosine harmonic coefficients of each order of the displacement error curve are obtained, and after comparison and screening, The harmonics whose values ​​are greater than the set threshold and whose influence on the error result exceeds the set error threshold, namely the 0th, 2nd and 4th order harmonics, realize the compensation reconstruction of the displacement sensor error data. Figure 4 The results show the angular displacement error compensation effect of this method when the turntable rotates at high speed.

[0029] Step 5: Set the turntable closed-loop control process so that the transfer function remains stable after parameter transformation. Assume that R is the input signal, C is the output signal, and N is the interference signal related to system friction and variable load. For the front control link, is the controlled object, H is the transfer function of the closed-loop control system, and according to the system signal superposition principle, the total output signal can be obtained as follows: (8) The interpolation of the theoretical angular displacement and the actual angular displacement of the calculation system can obtain the system error: , error change rate , and Respectively and The first derivative of .

[0030] Step 6: Compare the actual speed of the high-speed turntable motor obtained in step 4 with the expected speed, and input the error e and error change rate To the fuzzy controller, specifically, the fuzzy controller uses the output to perform online correction on the parameters of the PID controller to achieve the desired control effect. If the error e and the error change rate As the input variable of the fuzzy PID controller, the proportional coefficient is set according to the definition domain of the quantization factor and the proportional factor. The fuzzy domain is {-3,-2,-1,0,1,2,3}, and the integral coefficient is set and the differential coefficient The fuzzy domain is {-0.3,-0.2,-0.1,0,0.1,0.2,0.3}, and the fuzzy set describing the input and output is {NB,NM,NS,Z,PS,PM,PB}. The membership function of the fuzzy controller is based on the commonly used combination of trigonometric function and Gaussian membership function in engineering. Figure 5 A membership function distribution curve graph showing the error e trigonometric function combined with the Gaussian membership function.

[0031] Step 7: Detect turntable error and output fuzzy control self-adjustment parameters Used to correct control parameters. The specific method is to reason based on the fuzzy control rules of the parameters and combine them with the minimum operation algorithm to obtain the fuzzy results. ,in Represents error e and error change rate After the intermediate value of fuzzy inference, it is defuzzified based on the centroid method to obtain , taking the proportional coefficient as an example, we can get: (9) Based on the adjustment parameters obtained by the fuzzy controller, the original control parameters of the PID controller are corrected to obtain , , and Indicates the PID parameters obtained in the previous calibration. Continuously adjust the response rate, oscillation amplitude and stabilization time of the variable load turntable system.

[0032] Step 8: Adjust the driving state of the servo motor according to the PID control parameters given in step 7, transmit the corrected PID parameter signal to the servo motor driver, adjust the servo motor output current to compare the turntable system torque, speed and position, and then realize continuous adaptive control of the high-speed turntable speed. Figure 6 It is shown that under the action of pulse signals, the response time of this method is shorter and the overshoot effect is weaker than that of the traditional method; Figure 7 It shows that when a disturbance signal is given to the system, this method has stronger anti-interference ability than the traditional method, and the system output is more stable; Figure 8 It is shown that when the sinusoidal signal is maintained continuously, the system output under the action of this method is more consistent with the set signal, and has better followability than the traditional method.

[0033] The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A high-speed turntable variable load adaptive control method, characterized in that: Based on the closed-loop control method combined with the fuzzy PID control algorithm and the displacement sensor error compensation model, the adaptive control of the high-speed turntable in the disturbance environment and the variable load working environment is realized, which specifically includes the following steps: Step 1: Get the initial state of the high-speed turntable and controller, and send closed-loop instructions for the required position and speed; Step 2: Establish the motor transfer function of the turntable drive servo system; Step 3: The displacement sensor detects the angular displacement of the high-speed turntable, obtains the interpolation function value of each data point according to the interpolation principle, and obtains the interpolation curve of the data; Step 4: Reconstruct the interpolation curve in step 3 to obtain the amplitude and phase information of each order harmonic and construct the sensor error compensation model; Step 5: Set the turntable closed-loop control process so that the transfer function remains stable after parameter transformation; Step 6: Compare the actual speed of the high-speed turntable motor obtained in step 4 with the expected speed, and input the error e and error change rate to fuzzy PID controller; Step 7: Detect turntable error and output fuzzy control self-adjustment parameters Used to modify control parameters; Step 8: Adjust the driving state of the servo motor according to the PID control parameters given in step 7 to achieve continuous adaptive control of the high-speed turntable speed.

2. The variable load adaptive control method for a high-speed turntable according to claim 1 is characterized in that: Step 1 is as follows: The host computer obtains basic information related to the high-speed turntable and servo motor, including speed limit, torque limit and safe operating parameters; performs the initialization process of checking hardware connections, calibrating sensors, and setting initial parameters; sends closed-loop control instructions of the required position and speed to the actuator according to the requirements of the machine tool processing workpiece, and starts the high-speed turntable through the servo amplifier drive motor.

3. A high-speed turntable variable load adaptive control method according to claim 1 or 2, characterized in that: Step 2 is as follows: Assuming that the mass and shape of each component in the turntable system are uniform, the friction force in the turntable system is As a function of the actual position and speed, the torque balance equation of the servo system is: (1) in, is the moment of inertia, is the actual angular displacement of the system, is the system speed, is the output torque, For system load, set is the theoretical angular displacement of the system, then the motor transfer function Can be considered as and If the ratio is the Laplace variable, is the motor reduction ratio, and the changed motor transfer function is: (2) The changed motor transfer function is used as the basis for subsequent feedback control.

4. The variable load adaptive control method for a high-speed turntable according to claim 3 is characterized in that: Step 3 is as follows: The improved center-of-gravity Lagrange interpolation method is used to calculate the values ​​near the discrete displacement angle points of the high-speed turntable recorded by the displacement sensor; K+1 nodes are taken on the data interval [a, b] , then the displacement angle value of the corresponding node for: (3) According to formula (4), the Lagrange basic polynomial is defined as and center of gravity , according to the improved Lagrange interpolation method, the values ​​near the K+1 finite node displacement points are calculated, that is, the interpolation polynomial near the end point of the data interval is used to deal with the problem of displacement curve oscillation caused by load changes, and the displacement angle value can be obtained for: (4) Thus, the displacement sensor position information and the corresponding sensor angle information are obtained.

5. The variable load adaptive control method for a high-speed turntable according to claim 4, characterized in that: Step 4 is as follows: Based on Fourier expansion and convergence theorem, the interpolation curve is reconstructed into a finite sine wave according to the relationship between phase, amplitude and frequency, and the sensor displacement error value is decomposed. for: (5) (6) in, is the harmonic order, is the constant term coefficient, is the cosine wave coefficient, is the error value sine wave frequency information, is the harmonic amplitude, and the phase can be obtained by calculating the inverse tangent of the ratio of the displacement error harmonic coefficients; according to the sampling theorem, k+1 nodes are extracted within the curve period, and the maximum number of fitted periodic terms is set to n(k+1), then the coefficient value of the Fourier series fitting error function is inversely calculated as: (7) Thus, the sine and cosine harmonic coefficients of each order of the interpolation curve are obtained. The harmonics whose values ​​are greater than the set threshold and whose influence on the error result exceeds the set error threshold, namely the 0th, 2nd and 4th order harmonics, realize the compensation reconstruction of the displacement sensor error data.

6. A high-speed turntable variable load adaptive control method according to claim 4, characterized in that: Step 5 is as follows: Assume that R is the input signal, C is the output signal, and N is the interference signal related to system friction and variable load. For the front control link, is the controlled object, H is the transfer function of the closed-loop control system, and according to the system signal superposition principle, the total output signal can be obtained as follows: (8) The interpolation of the theoretical angular displacement and the actual angular displacement of the calculation system can obtain the system error: , error change rate , and Respectively and The first derivative of .

7. A high-speed turntable variable load adaptive control method according to claim 6, characterized in that: Step 6 is as follows: The fuzzy controller uses the output to perform online correction on the parameters of the PID controller to achieve the desired control effect. If the system error e and the error change rate As the input variable of the fuzzy PID controller, the proportional coefficient is set according to the definition domain of the quantization factor and the proportional factor. The fuzzy domain is {-3,-2,-1,0,1,2,3}, and the integral coefficient is set and the differential coefficient The fuzzy domain is {-0.3, -0.2, -0.1, 0, 0.1, 0.2, 0.3}, the fuzzy set describing the input and output is {NB, NM, NS, Z, PS, PM, PB}, and the membership function of the fuzzy controller is a combination of trigonometric functions and Gaussian membership functions commonly used in engineering.

8. The variable load adaptive control method for a high-speed turntable according to claim 6, characterized in that: Step 7 is as follows: According to the fuzzy control rules of the parameters combined with the minimum operation algorithm, the fuzzy result is obtained. ,in Represents the system error e and the error change rate After the intermediate value of fuzzy inference, it is defuzzified based on the centroid method to obtain , proportionality coefficient We can get: (9) in, The solution and same; Based on the adjustment parameters obtained by the fuzzy controller, the original control parameters of the PID controller are corrected to obtain , , and Indicates the PID parameters obtained from the previous calibration.

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