Active Disturbance Rejection Controller Tuning And Its Application To Precision Control Based On Frequency Model

Tracking accuracy is an important index to measure the performance of photoelectric precision control system. In order to improve the tracking performance of system,this paper chiefly researches the application of ADRC in precise control system,including system model established,ADRC parameter tuning,ADRC in the application of speed loop and its application in multiple closed-loop control structure and so no.The purpose is to find an effective parameter tuning method from the perspective of frequency domain,and apply ADRC in precision control system to improve the tracking precision.First,the mathematical model of photoelectric precision control system is established, and then we obtain the transfer function of the control object through the system identification method.Based on the frequency domain model of control object,the paper uses the second order linear ADRC to analysis,greatly reduces the number of parameter with the introduction of controller bandwidthc? and observer bandwidth 0?.Then this paper gives tuning method to each parameter and summarizes the parameter tuning procedure.In the process of parameter tuning,this paper finds out the mathematical relationship between controller parameter b and the system resonant frequency,which makes the parameter b tuning simple.The accuracy of parameter tuning is verified through the simulation analysis.Speed closed-loop is very important in the precision control system.Speed closed-loop with high performance can not only eliminate the disturbance,but also provide good object properties for position loop.ADRC based on the above tuning method is used in speed loop of precision control system to alleviate disturbances and in comparison with conventional PI controller.The experiment results show that ADRC reduces the directional error and achieves high-precision tracking control performances.In most control systems,multiple closed-loop control structure is commonly used to improve response accuracy and response time.This paper does some improvement on the control law of original ADRC,and proposes an improved ADRC which based on the PI control law,then applies it in multiple closed-loop control structure(including speed loop and positon loop) to analysis its position tracking performance.There we do two cascade control experiments:speed loop with ADRC and position loop with PID, speed loop with ADRC and position loop with ADRC. Experiments show that the improved ADRC based PI control law can reduce the tracking error and improves tracking accuracy of the system,which has strong anti-disturbance capability.The research results show that ADRC has a certain application prospect in precision control system.