The Design Of Fuzzy Self-Tuning PID Controller

Because the performance of conventional PID control and fuzzy control is no prefect, this text designed a fuzzy self-tuning PID controller, and modified the algorithm of the controller. The fuzzy PID controller is made of PID controller and fuzzy controller, based on the existing control algorithm and boiler temperature regulator for controlled object. The research of the thesis is significant in modern industrial control.First of all, the paper analyzed PID control technology and fuzzy control technology, and summarized their disadvantages and development trend. And then this paper designed fuzzy self-tuning PID controller by combining PID control and fuzzy control. The fuzzy self-tuning PID controller will deduce and calculate the output value by the fuzzy rule, which is summarized with expert's knowledge and practical experience from operators, then add the values to the original values that have been set,and get the final value. Finally, the controller will control the object by inputting the value to the execution unit.Theoretically, the fuzzy self-tuning PID controller has better performance and higher control precision, which will show obvious advantages than fuzzy and PID control on the regulation of control system. However, the calculation and reasoning of fuzzy rules is very complex, which can affect the calculation precision to some extent and make the output value different from the actual output value. When the D-value is too big, it will affect the stability of the control system. Based on this case, this paper designed an improved fuzzy self-tuning PID controller, which input the method of variable universe and reducing differential to the modified control algorithm. The modified controller has higher control precision, which makes the process of fuzzification and defuzzification more simple by reducing the reasoning and calculation of differential.Finally, the paper analyzed and summarized the control effect of PID controller,fuzzy controller,fuzzy self-tuning controller and modified fuzzy self-tuning controller, and all the simulation based on the boiler temperature regulator for controlled object.