The Design Of Fuzzy Liquid Level Controller Based On The Siemens PLC

The conventional PID control is a control method which is the most widely used in the field of industrial process control. It's playing out its advantages of simple structure and good reliability and robustness, especially being used for the control objects that are able to build their accurate models. In reality, the actual process of industrial production are often non-linear, time-varying uncertainty so that it's hard to establish the precise mathematical model. In that case, the conventional PID control can't satisfy the controlling requirements, so we need a new way to solve this problem. That's fuzzy control.Fuzzy control is one of intelligent control methods, it developed the fuzzy set theory and combined with the automatic control technology. Up to now, fuzzy control is used in lots of practical engineering projects which aren't able to build their accurate models.In this thesis, my experiment object is liquid level control system. I build the model through the method of experiment and design the fussy liquid level controller. After choosing the appropriate membership functions and fussy control rules, I simulate the controller in the Matlab/Simulink environment, then, carrying out the application in Siemens PLC. Finally, I compare the control performance with that of the experiment using by the conventional PID control, and the results show that fussy control has better control performance.