Abstract:

PID control theory is utilized to deal with the problems of simple input/output control,discontinuous liquid mixing and poor accuracy.There are some problems in traditional PID control,such as troubles in adjustment after the state change of the system,large overshoot and long setting time.In combination with the fuzzy theory,flow valves are adjusted and all disturbances in the system will be eliminated to achieve the accurate mixture.PLC realizes the fuzzy self tuning PID and manages with input/output control.It has advantages of continuous and discontinuous operation,less overshoot and good robustness.Its overshot is 36% less than that of the traditional PID.Moreover,the setting time is reduced by 3 seconds with higher production efficiency and lower labour cost.

Key words: fuzzy self-tuning PID;flow control;Simulink