Comparative Analysis of Classical and Fuzzy Pid Control Algorithms

A fuzzy PID controllers are physically related to classical PID controller. The settings of classical controllers is based on deep common physical background. Fuzzy controller can embody better behaviour comparing with classical linear PID controller because of its non linear characteristics. Well tuned fuzzy controller can be also more stable and more robust for the time varying systems. On the other hand, when the fuzzy controller is tuned badly it can exhibit limit cycle which can decrease lifetime of the actuator. This phenomenon is critical especially when the actuator is valve. Knowing about these problems, more analytical methods of tuning fuzzy controllers can be found. The method with unified universe considerably simplifies the setting and realisation of fuzzy controllers. This paper tries to analyse causes of oscillations and it outlines the possibilities how to reduce them. The paper also shows solution how to reduce time needed for computation of control signal by decreasing the number of membership functions and by changing defuzzification method.