Delay Systems Of The Two Degree Of Freedom Fuzzy Controller

Time delay is very common in industrial control process, which results the disturbance to the system unable to be reflected timely, the dynamic error of the system increase and stability margin decrease, and even causes the system oscillate. Therefore, the control method of time delay process is still a hot issue to be studied in control theory and control engineering.With the development of science technology and automation technology, the requirement of the production process quality control has been increased, the designed system must have the performance such as high accuracy, better robustness, and anti-jamming capability. Meanwhile, due to the complexity of control systems, it is difficult to obtain a precise mathematical model of the controlled object. So it is necessary to research a control approach which has less dependence on the model.For the problems metioned above, the designed method of fuzzy PI-Smith predictor controller is proposed, in which PI control is introduced to the fuzzy smith predictor controller in order to eliminate the steady-state error. At the same time, the sufficient condition for fuzzy PID controller is derived, which provides a guidence for the regulation of the fuzzy rules. Based on internal model control principle, the designed method for internal model control(IMC) system equivalent to PID controller is advanced, the parameter ajustment rule is given when the internal model mismatches. Because fuzzy control does not require an accurate model of the controlled object, it is combined with two-degree of freedom internal model control method to design a fuzzy two-degree of freedom internal model controller. The obtained controller makes the closed-loop system have good tracking properties, anti-interference characteristics and better robustness even when the internal model mismatches. The simulation results show the effectness of the proposed method.