Research On PID Controller Parameter Auto-Tuning Method

The paper deeply studies the PID control theory and re-analyses the control principle of the PID control, and surveys and discusses the different kinds of PID parameter tuning methods and recent researching achievements on this subject. According to the simple, easy-to-use, intuitive principle of the parameter tuning and the purpose of really improving system control performance, Several modified auto-tuning methods of PID controller parameter are proposed. Based on step identification PID parameter auto-tuning method is to obtain dynamic characteristics of the process through step response experiment, then identify a low-order approximate model with higher precision. PID controller is designed to satisfy phase margin and gain margin given. Based on modified relay identification Smith predictor controller is to obtain the critical point information of the process through saturation relay experiment, So essential improving precision model identification, and combining Smith predictive controller to overcome the case that a larger dead time process can't be effectively controlled for PID controller. Based on sequential relay identification PID parameter auto-tuning method is to obtain the static gain and critical point information of the process through sequentially performing relay feedback test with input-biased and saturation relay test, then based on internal model principle designing robust controller to improving performance. Based on twice modified relay identification and multi-point frequency characteristics PID parameter auto-tuning method is to identify special point information through modifying relay experiment, then design PID controller so as to satisfy phase margin and gain margin given or desirable closed-loop characteristics, the ideal control performance is obtained for a number of special process and more difficult control process. The paper proposes some auto-tuning methods carrying out computer simulation experiment respectively, and get some beneficial simulated conclusion. The practical control effect is wait to further practice in actual process control.