The Fuzzy Logical Self-tuning PID Controller Based On Relay Self-tuning

PID controller is widely used in most of industrial process control, because of its simple structure, its easy realization and its robustness. To be a widely-used control arithmetic, PID controller had not be substituted for some advanced controlling arithmetic in a long time, on the contrary, the PID control is still on the main station of many kinds of controlling technique as time.Whether the PID controller can keep the control performance good is due to the tuning of the PID parameter. So far,there are many kinds of methods in the tuning of PID parameter . These methods have brought the energy for the research of the tuning of PID parameter. Such as: ZN method, relay self-tuning and so on. And the relay self-tuning method is used widely in the industrial control because of its simpleness, practicality and efficiency. But in fact, most of industrial process is non-linear, dynamic parameter and time-lag, the general methods couldn't keep the good control performance. So, for get the good control performance, it is needed that not only the tuning of PID parameter doesn't rely on the process model, but also the PID parameter can be adjust on-line.The paper presents the fuzzy logical self-tuning PID controller based on relay self-tuning. The method effectively applies the expert's experience in the self-tuning PID controller, and improves the control performance of relay self-tuning on PM. Firstly, the paper introduces the classic methods of the PID parameter tuning in the past years; secondly, it introduces the relay self-tuning method and the fuzzy logical self-tuning of PID parameter; lastly, it presents the new method, and uses a plant of one order plus time-delay on MATLAB to simulate. The there methods'——ZN-method, relay self-tuning on PM method and the new method simulation results show that: the new strategy of PID parameter tuning is very good at control performance,and has good behavior in disturbance-rejection performance.