DESIGN AND EVALUATION OF MODIFIED ADAPTIVE FUZZY PID CONTROLLER

Abstract

The need for advanced but simple automatic control alternatives arises especially in the process control area, where most of the real processes are generally non-linear, complex, time-variant, delayed and difficult to model. The application of Fuzzy Logic to a wide range of control applications has made the establishment of intelligent control possible in these areas. Fuzzy control is the boundary line between artificial intelligence and control engineering. This provides good support for representing, manipulating and implementing both the heuristic knowledge of a skilled operator about the process and control procedures, into numerical algorithms. Fuzzy control solves real problems, previously not tackled due to their complexity or to lack of information. Most of process control systems are based on PID controllers, because of their remarkable effectiveness, simplicity and robustness. As PID controller design theory and practical procedures are well developed, it is necessary to pay attention on fuzzy logic controller design and its applications in combinations with PID controllers. There is also a necessity to develop adaptive fuzzy PID controllers, which can automatically retune itself to match the current process characteristics. In particular, focus of the work presented here is mainly on two problems: replacing an operator's control of PID regulators with fuzzy PID controller and to develop a structure for self-tuning fuzzy PID as modified adaptive fuzzy PID controller.