Modelling and analysis of a general Takagi-Sugeno fuzzy PI/PD controller with modified rule base

This paper deals with a general Takagi-Sugeno (TS) fuzzy PI/PD controller with a modified rule base. The analytical structure and properties of the fuzzy PI/PD controller are investigated. The rule base contains three rules which reduce the tuning parameters of the controller. The input variables are fuzzified by at least three triangular or trapezoidal fuzzy sets. The fuzzy PI/PD controller uses algebraic product triangular norm, bounded sum triangular co-norm, and center of gravity (CoG) defuzzification method. The fuzzy PI/PD controller with modified TS rule base is analogous to a variable gain (nonlinear) PI/PD controller. In different regions of the input plane, the gain either varies or remains constant. The gain variations of the controller and the stability analysis of closed loop control system have been investigated.