| It is over fifty years for PID controller be the most general control method in industrial control. And now PID controller is still used most widely. It has many advantages, such as its simple structure, strong robustness, stable state without steady-state error and easy to operate etc. Thus it has been used in industry for a long time. But the limitation for the application of complex controlled object is one of important factors of restricting its development. With the development of IC (intelligent control), fuzzy control theory has been mature and fuzzy control technology has been come into being. This brings new vitality for the development of PID control. Combination of fuzzy control and PID control remedies the shortage of each others. On the one hand, the coming of fuzzy control remedies the shortage of PID control for complex object such as the object with great delay and the nonlinear object. On the other hand, the combination of PID control and fuzzy control gets improvement in rough control quality and low steady-state precision in greet degree.Rough Set has the ability that acquires knowledge from learning numbers of data. In this thesis, Rough Set is applied to fuzzy controller. The original data can be processed and the fuzzy rules can be extracted from data directly, which reduces the difficulty of obtaining rules in fuzzy controller.Every parameter determination of PID controller is the key that if it can reach the satisfactory control effect. A kind of new optimization method-ACA is applied to optimize the parameters of PID controller. ACA is a population-based simulated evolutionary algorithm. The PID parameter optimization algorithm based on ACA has the advantages of rapid convergence speed, high calculate precision and convenient operation.Eventually, a hybrid intelligent Fuzzy-PID control system with fuzzy controller based on RS and PID controller based on ACA has been designed in the thesis. Two optimization methods introduced in the upper article are blent in tradition Fuzzy-PID hybrid control to realize the Fuzzy-PID control system intelligent. Aimed the defect switching course of this controller, a switching algorithm based on fuzzy rules is used to modify. The simulation result proved this method superiority on improving the controller performance.Finally, Make some experiments on several complex object, the simulation results show control performance of this intelligent control system is super and the designing can make control effect satisfying.Some deep research about Rough Set is made in this thesis. It is applied to handle the data which is collected from pet industrial process and the result of reduction accords with the real technics situation. It is explained that Rough Set can be applied to modeling and analyzing technics parameters which determine the quality of prduct. So it is embodied the meanings of Rough Set in chemical analysis. |
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