An automatic PID parameter setting method for digital accelerometer servo control system

Abstract

The invention discloses an automatic PID parameter setting method for a digital accelerometer servo control system, comprising: inputting system-related performance index requirements; detecting the boundary of a meter head capacitor to determine the capacitor boundary value; debugging a proportional coefficient with a critical oscillation as a boundary condition, and debugging an integral coefficient with a control object unit step balance time as an index when the pulse response under the proportional coefficient can reach a maximum amplitude theoretically to meet the engineering index; finally debugging a differential coefficient with a unit step response rise time and a system overshoot as indexes to preliminarily complete system control; gradually weakening the proportional action based on a pulse response designated index and a rise time designated index, and then adjusting the integral action based on the control object unit step balance time, and finally gradually weakening the differential action based on a pulse response under a unit step that can reach a maximum amplitude theoretically or a system overshoot and a rise time designated index.

Description

Technical Field

[0001] The invention relates to the technical field of digital accelerometer control, and in particular to an automatic PID parameter setting method for a digital accelerometer servo control system. Background Art

[0002] In a PID controller, the three parameters P, I, and D need to be set. Generally, the process is tried and tested by engineers' experience and skills. This process is called PID tuning. There have been a lot of studies on automatic tuning of PID parameters, and it has been applied to many fields. For example, the patent specification with publication number CN110588654A discloses a method for automatically tuning the PID control parameters corresponding to vehicle speed, and the patent specification with publication number CN110617152A discloses a throttle control system based on fuzzy PID control, and introduces the ZN formula as an engineering method for tuning PID parameters.

[0003] The digital accelerometer includes a meter and a digital servo control circuit. The servo circuit collects the meter capacitance and transmits it to the digital controller through AD conversion, and then applies feedback torque to the meter through DA conversion and the drive circuit to form a closed loop. Compared with traditional analog accelerometers, the control parameter debugging of digital accelerometers can be directly debugged through software programming. With the large-scale production and application of digital accelerometers, higher requirements are put forward for the automation of parameter debugging of digital accelerometer closed-loop control systems.

[0004] In previous project designs, the debugging of the control parameters (proportional coefficient, integral coefficient, differential coefficient) of the digital accelerometer closed-loop system PID controller basically relies on experience-based debugging. Without a certain theoretical foundation and debugging experience, the control parameter debugging and adjustment not only greatly increases the workload of on-site personnel, but also increases the risk of unstable operation of the digital accelerometer closed-loop system.

[0005] In the past, there was no clear standard for debugging the control parameters of the closed-loop system of digital accelerometers. Only stable control was used as the standard, and it was often impossible to obtain control parameters that fully meet the dynamic performance indicators of each system. At the same time, in order to improve the applicability of digital accelerometer products, it has become more important to obtain the critical control parameters corresponding to the system under different indicators according to different predetermined indicators. Summary of the invention

[0006] In view of the above technical problems and the shortcomings in the field, the present invention combines the PID control algorithm with the characteristics of the digital accelerometer servo control loop from the perspective of engineering application, and proposes an automatic PID parameter tuning method for a digital accelerometer servo control system.

[0007] The specific technical solutions are as follows:

[0008] An automatic PID parameter setting method for a digital accelerometer servo control system comprises the following steps:

[0009] S1. Input system related performance index requirements, including: system overshoot, rise time, unit step equilibrium time, and pulse response;

[0010] S2, meter head capacitance boundary detection, determine the capacitance boundary value, that is, the control object (i.e. capacitance) change range;

[0011] S3. Debug the proportional coefficient with critical oscillation as the boundary condition. When the impulse response theory under this proportional coefficient can reach the maximum amplitude to meet the engineering indicators, debug the integral coefficient with the unit step equilibrium time of the control object as the indicator. Finally, debug the differential coefficient with the rise time of the unit step response and the system overshoot as the indicators, and preliminarily complete the system control.

[0012] S4. Gradually weaken the proportional effect based on the pulse response specified index and the rise time specified index to determine the final proportional coefficient. Secondly, adjust the integral effect based on the unit step equilibrium time of the control object to determine the final integral coefficient. Finally, gradually weaken the differential effect based on the maximum amplitude of the pulse response theory under unit step or the specified index of the system overshoot and rise time to determine the final differential coefficient.

[0013] In step S1, the automatic PID parameter tuning program of the digital accelerometer servo control system needs to input system-related performance index requirements before performing parameter tuning, including: system overshoot, rise time, unit step equilibrium time and pulse response.

[0014] In step S2, the meter head is placed at zero position, and the microprocessor is programmed to make the controller output positive and negative excitations of the same amplitude, gradually increasing the excitation amplitude until the meter head capacitance reaches the boundary, and the meter head capacitance value, i.e., the capacitance boundary value, is measured.

[0015] The operation of debugging the proportional coefficient in step S3 is specifically as follows: gradually increase the proportional coefficient until the meter head capacitance just deviates from the capacitance boundary value, and then gradually increase the proportional coefficient at this time as the minimum unit amplitude until the controlled object exhibits equal-amplitude oscillation, record the critical proportional coefficient at this time, and take 90% of the critical proportional coefficient as the debugged proportional coefficient.

[0016] The maximum amplitude of the impulse response theory in the present invention is calculated by the following formula (1):

[0017] pulse=cap / step_1g (1)

[0018] In formula (1), pulse is the maximum amplitude that can be achieved in pulse response theory, cap is the capacitance boundary value, and step_1g is the stable value of the capacitance output under the step response test with an amplitude of 1g (i.e., 1 gravitational acceleration).

[0019] In step S3, if the calculated maximum amplitude of the impulse response theory does not meet the engineering specifications, the system parameter tuning is terminated, and the system is adjusted until the maximum amplitude of the impulse response theory meets the engineering specifications.

[0020] The operation of debugging the integral coefficient with the unit step balancing time of the control object as an indicator in step S3 is specifically: gradually increase the integral coefficient, test the 1g amplitude step response of the system, until the time for the control object to balance to zero is less than 1000 control cycles.

[0021] The operation of debugging the differential coefficient with the rise time of the unit step response and the system overshoot as indicators in step S3 is specifically as follows: gradually increase the differential coefficient, test the system 1g amplitude step response, until the system overshoot of the controller output response is less than 20% and the rise time is less than 50 control cycles, or until oscillation occurs, record the critical differential coefficient at this time, and take 90% of the critical differential coefficient as the debugged differential coefficient.

[0022] The operation of gradually weakening the proportional effect based on the pulse response specified index and the rise time specified index in step S4 is specifically as follows: gradually reduce the proportional coefficient with the minimum unit amplitude of the proportional coefficient obtained in step S3, and test the system 1g amplitude step response until the pulse response can theoretically reach a maximum amplitude greater than but as close as possible to the pulse response specified index and the rise time is less than but as close as possible to the rise time specified index. The proportional coefficient at this time is the final proportional coefficient.

[0023] In step S4, the operation of adjusting the integral action based on the unit step balancing time of the control object is specifically as follows: adjusting the integral coefficient, testing the 1g amplitude step response of the system, until the time for the control object to balance to zero is 900-1100 control cycles, and the integral coefficient at this time is the final integral coefficient.

[0024] In step S4, the operation of gradually weakening the differential effect based on the theoretical maximum amplitude of the impulse response under a unit step or the specified indicators of the system overshoot and rise time is specifically as follows: gradually reduce the differential coefficient, test the capacitor output stability value under the system 1g amplitude step response and calculate the theoretical maximum amplitude of the impulse response, until the calculated theoretical maximum amplitude of the impulse response is as close as possible but still greater than the specified indicator, or until the system overshoot of the controller output response is not less than 20% and the rise time is not less than 50 control cycles. The differential coefficient at this time is the final differential coefficient.

[0025] The reason for debugging the proportional coefficient first in step S4 is that the proportional coefficient has a decisive influence on the system impulse response index, and the change of the proportional coefficient will affect the evaluation index of the integral coefficient and the differential coefficient. Therefore, when performing parameter optimization, priority is given to the optimization of the proportional coefficient, and there is no influence between the balance time index of the integral coefficient and the overshoot and rise time index of the differential coefficient. However, the balance time of the integral coefficient needs to observe the output change of the controlled object, while the overshoot and rise time index of the differential coefficient need to observe the output change of the controller. Therefore, when considering the debugging and optimization of the proportional coefficient, it is also necessary to observe the 1g response stable amplitude of the controlled object. In order to simplify the debugging steps, after the proportional coefficient is optimized, the integral coefficient is optimized, and finally the differential coefficient is optimized.

[0026] The main parameters to be optimized in the present invention are the proportional coefficient and the differential coefficient, wherein the proportional coefficient is a decisive parameter for system control. When the coefficient is small, the pulse response amplitude of the system control object is large, and when the coefficient is large, the system overshoot is large; the differential coefficient can improve the dynamic performance of the system. When the coefficient is small, the improvement in dynamic performance is small. When the coefficient is large, the output noise will be increased, affecting the static performance of the system and even causing oscillation; the integral coefficient is directly related to the balance time of the control object and has no obvious correlation with other dynamic indicators.

[0027] After the parameters are adjusted according to the steps of the method of the present invention, the finally obtained proportional coefficient is the critical proportional coefficient that can meet the system pulse response index; the finally obtained integral coefficient is the critical integral coefficient that can meet the balance time index of the system control object under unit step disturbance; the finally obtained differential coefficient is the critical differential coefficient that meets the system overshoot and rise time indexes when the proportional coefficient is fixed. These critical control parameters are directly applied to the closed-loop system controller to obtain a digital accelerometer servo control system after weighing the dynamic indicators of the system.

[0028] The method of the present invention can perform online automatic control parameter self-tuning, and at the same time can obtain control parameters after weighing the system dynamic indicators and static noise while meeting the system hard indicators, greatly reducing the ability and experience requirements for debugging personnel and improving debugging efficiency; the present invention has been successfully applied to digital quartz flexible accelerometers and is suitable for typical single-loop PID control systems that conform to the digital quartz flexible accelerometer model.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The method of the present invention relies on the control characteristics of the PID control algorithm itself, and can test whether the control parameters of the digital accelerometer servo control system meet the upper limit of control and the lower limit of parameters that meet the specified dynamic indicators, while providing a screening basis for digital accelerometers that do not meet the predetermined indicators.

[0031] 2. The method of the present invention can adjust the control parameters based on the dynamic performance indicators required by the system, thereby improving the comprehensive performance and applicability of the digital accelerometer system.

[0032] 3. The method of the present invention can write an automated program based on the flow chart to perform online parameter tuning, and the parameter optimization depends on the actual system, abandoning the system model identification process, greatly simplifying the parameter tuning steps, improving the efficiency of control parameter tuning, and reducing the workload of on-site personnel debugging and the risk of unstable system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of an automatic PID parameter tuning method of a digital accelerometer servo control system in a specific embodiment of the present invention;

[0034] Figure 2 It is a flow chart of automatic pre-debugging of control parameter proportional coefficient and pre-evaluation of impulse response index in a specific implementation mode of the present invention;

[0035] Figure 3 This is a flow chart of automatic pre-debugging of control parameter integral coefficient in a specific implementation mode of the present invention;

[0036] Figure 4 This is a flow chart of automatic pre-debugging of differential coefficients of control parameters in a specific implementation mode of the present invention;

[0037] Figure 5 This is a flow chart of control parameter optimization in a specific implementation manner of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0039] like Figure 1 As shown, an automatic PID parameter tuning method for a digital accelerometer servo control system, the method specifically includes:

[0040] Step 1: Before setting the parameters of the automatic PID parameter setting program, you need to input the system-related performance index requirements, including: system overshoot, rise time, unit step equilibrium time, and pulse response.

[0041] Step 2: Meter head capacitance boundary detection. Place the meter near zero position and program the microprocessor to make the controller output positive and negative excitations of the same amplitude. Gradually increase the excitation amplitude until the meter head capacitance reaches the boundary. Measure the meter head capacitance value, that is, the capacitance boundary value, which is the range of change of the controlled object. At the same time, perform preliminary detection of the functions of each link of the control system.

[0042] Step 3: First, adjust the proportional coefficient based on the critical oscillation as the boundary condition, and make a preliminary evaluation of the system pulse response index. Then, adjust the integral coefficient based on the step response balance time of the control object as the index. Finally, adjust the differential coefficient based on the rise time and overshoot of the step response as the index to preliminarily complete the system control. Specifically:

[0043] like Figure 2 As shown, first gradually increase the controller proportional coefficient until the meter head capacitance just deviates from the boundary, and then use the coefficient kp at this time min The minimum unit amplitude gradually increases until the controlled object shows equal amplitude oscillation, and the critical proportional coefficient kp is recorded at this time max , and take 90% of the critical proportional coefficient as the proportional coefficient; test the control system 1g amplitude step response, and record the step response capacitance stability value step_1g, and further conduct a preliminary evaluation of the system pulse response index. If the system theoretical pulse response index does not meet the engineering index (the system pulse response engineering index of the specific implementation method of the present invention is set to 8g), the system parameter setting is terminated, and the system is adjusted until the engineering index is met;

[0044] The pulse response theory can be calculated by the following formula: pulse = cap / step_1g

[0045] Where pulse is the maximum amplitude of the theoretically calculated system pulse response, cap is the capacitance boundary value obtained from the test in step 2, and step_1g is the capacitance output stability value under the 1g amplitude step response test.

[0046] like Figure 3 As shown, when the theoretical pulse response index meets the predetermined index, the integral coefficient is gradually increased to test the 1g amplitude step response of the control system, with the time for the controlled object capacitance to balance to zero as the index, until the capacitance step balance time is less than 1000 control cycles.

[0047] like Figure 4 As shown, the differential coefficient is gradually increased to test the control system 1g amplitude step response, with the overshoot (less than 20%) and rise time (less than 50 control cycles) of the controller output response as indicators, until the specified dynamic index requirements are met, or the occurrence of oscillation is used as an indicator, and 90% of the critical differential coefficient is taken as the differential coefficient. In the specific implementation of the present invention, the rise time is the time between the rising section of the final value 0.25% to 70.7% amplitude.

[0048] Step 4: gradually weaken the proportional action based on the pulse response specified index and the rise time specified index, then adjust the integral action based on the control object balance time, and finally gradually weaken the differential action based on the system overshoot specified index.

[0049] like Figure 5 As shown, first test the minimum amplitude kp of the proportional coefficient obtained in step 3 min Gradually reduce the proportional coefficient, test the 1g amplitude step response of the control system, based on the maximum amplitude of the impulse response theory corresponding to the stable value of the 1g step capacitor output and the controller output rise time rise_time, until the maximum amplitude of the impulse response theory is greater than but as close as possible to the specified index of the impulse response (the specific implementation method of the present invention sets the specified index to 9g here, and the remaining 1g amplitude is used for system parameter debugging) and the rise time is less than but as close as possible to the specified index of the rise time, record the critical proportional coefficient kp at this time mid ; At the same time, based on the capacitance balance time of the controlled object as an indicator, adjust the integral coefficient until the capacitance step balance time is 900-1100 control cycles (10% variation range); gradually reduce the differential coefficient, test the capacitance output stability value under the 1g amplitude step response of the control system and calculate the maximum amplitude that the impulse response can reach theoretically, until the calculated maximum amplitude of the impulse response is as close as possible but still greater than the specified indicator, or until the system overshoot of the controller output response is not less than 20% and the rise time is not less than 50 control cycles, record the critical differential coefficient kd at this time mid .

[0050] After the parameters are adjusted according to the above steps, the obtained proportional coefficient is the critical proportional coefficient that can meet the system pulse response index; the obtained integral coefficient is the critical integral coefficient that can meet the balance time index of the system control object under unit step disturbance; the obtained differential coefficient is the critical differential coefficient that meets the system overshoot and rise time indexes when the proportional coefficient is fixed. By directly applying these critical control parameters to the closed-loop system controller, a digital accelerometer servo control system can be obtained after weighing the dynamic indicators of the system.

[0051] The specific implementation mode of the present invention takes a certain type of digital quartz flexible accelerometer closed-loop control system as an example. The system adopts a digital PID controller integrated in a microprocessor, and the overall structure of the system conforms to the characteristics of a second-order system, and is suitable for the parameter pre-setting rules of step two and the control parameter optimization rules of step four of the present invention.

[0052] In step 4, based on Figure 5 The main parameters to be optimized are the proportional coefficient and the differential coefficient, among which the proportional coefficient is the decisive parameter of the system control. When the coefficient is small, the pulse response amplitude of the system control object is large, and when the coefficient is large, the system overshoot is large; the differential coefficient can improve the dynamic performance of the system. When the coefficient is small, the improvement of dynamic performance is small. When the coefficient is large, the output noise will be increased, affecting the static performance of the system and even causing oscillation; the integral coefficient is directly related to the balance time of the control object and has no obvious correlation with other dynamic indicators.

[0053] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. An automatic PID parameter setting method for a digital accelerometer servo control system, characterized in that: Includes steps: S1. Input system related performance index requirements, including: system overshoot, rise time, unit step equilibrium time, and pulse response; S2, meter head capacitance boundary detection, determine the capacitance boundary value, that is, the control object change range; S3. Debug the proportional coefficient with critical oscillation as the boundary condition. When the impulse response theory under this proportional coefficient can reach the maximum amplitude to meet the engineering indicators, debug the integral coefficient with the unit step equilibrium time of the control object as the indicator. Finally, debug the differential coefficient with the rise time of the unit step response and the system overshoot as the indicators, and preliminarily complete the system control. S4. Gradually weaken the proportional effect based on the pulse response specified index and the rise time specified index to determine the final proportional coefficient. Secondly, adjust the integral effect based on the unit step equilibrium time of the control object to determine the final integral coefficient. Finally, gradually weaken the differential effect based on the maximum amplitude of the pulse response theory under unit step or the specified index of the system overshoot and rise time to determine the final differential coefficient.

2. The automatic PID parameter setting method of the digital accelerometer servo control system according to claim 1, characterized in that: In step S2, the meter head is placed at zero position, and the microprocessor is programmed to make the controller output positive and negative excitations of the same amplitude, gradually increasing the excitation amplitude until the meter head capacitance reaches the boundary, and the meter head capacitance value, i.e., the capacitance boundary value, is measured.

3. The automatic PID parameter setting method of the digital accelerometer servo control system according to claim 1, characterized in that: The operation of debugging the proportional coefficient in step S3 is specifically as follows: gradually increase the proportional coefficient until the meter head capacitance just deviates from the capacitance boundary value, and then gradually increase the proportional coefficient at this time as the minimum unit amplitude until the controlled object exhibits equal-amplitude oscillation, record the critical proportional coefficient at this time, and take 90% of the critical proportional coefficient as the debugged proportional coefficient.

4. The automatic PID parameter setting method of the digital accelerometer servo control system according to claim 1, characterized in that: The maximum amplitude of impulse response theory can be calculated as follows: pulse=cap / step_1g (1) In formula (1), pulse is the maximum amplitude that can be achieved in pulse response theory, cap is the capacitance boundary value, and step_1g is the stable value of the capacitance output under the 1g amplitude step response test; In step S3, if the calculated maximum amplitude of the impulse response theory does not meet the engineering specifications, the system parameter tuning is terminated, and the system is adjusted until the maximum amplitude of the impulse response theory meets the engineering specifications.

5. The automatic PID parameter setting method of the digital accelerometer servo control system according to claim 1, characterized in that: The operation of debugging the integral coefficient with the unit step balancing time of the control object as an indicator in step S3 is specifically: gradually increase the integral coefficient, test the 1g amplitude step response of the system, until the time for the control object to balance to zero is less than 1000 control cycles.

6. The automatic PID parameter setting method of the digital accelerometer servo control system according to claim 1, characterized in that: The operation of debugging the differential coefficient with the rise time of the unit step response and the system overshoot as indicators in step S3 is specifically as follows: gradually increase the differential coefficient, test the system 1g amplitude step response, until the system overshoot of the controller output response is less than 20% and the rise time is less than 50 control cycles, or until oscillation occurs, record the critical differential coefficient at this time, and take 90% of the critical differential coefficient as the debugged differential coefficient.

7. The method for automatically setting PID parameters of a digital accelerometer servo control system according to claim 3, characterized in that: The operation of gradually weakening the proportional effect based on the pulse response specified index and the rise time specified index in step S4 is specifically as follows: gradually reduce the proportional coefficient with the minimum unit amplitude of the proportional coefficient obtained in step S3, and test the system 1g amplitude step response until the pulse response can theoretically reach a maximum amplitude greater than but as close as possible to the pulse response specified index and the rise time is less than but as close as possible to the rise time specified index. The proportional coefficient at this time is the final proportional coefficient.

8. The automatic PID parameter setting method of the digital accelerometer servo control system according to claim 1 or 5, characterized in that: In step S4, the operation of adjusting the integral action based on the unit step balancing time of the control object is specifically as follows: adjusting the integral coefficient, testing the 1g amplitude step response of the system, until the time for the control object to balance to zero is 900-1100 control cycles, and the integral coefficient at this time is the final integral coefficient.

9. The automatic PID parameter setting method of the digital accelerometer servo control system according to claim 1 or 6, characterized in that: In step S4, the operation of gradually weakening the differential effect based on the theoretical maximum amplitude of the impulse response under a unit step or the specified indicators of the system overshoot and rise time is specifically as follows: gradually reduce the differential coefficient, test the capacitor output stability value under the system 1g amplitude step response and calculate the theoretical maximum amplitude of the impulse response, until the calculated theoretical maximum amplitude of the impulse response is as close as possible but still greater than the specified indicator, or until the system overshoot of the controller output response is not less than 20% and the rise time is not less than 50 control cycles. The differential coefficient at this time is the final differential coefficient.

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