Tuning fuzzy feedback controllers using the circle criterion
Christine M. Haissig · 2002
This paper illustrates a method for tuning fuzzy feedback controllers using the circle criterion. The method can be used for design, tuning at commissioning, or online adaptation of systems consisting of a fuzzy feedback controller and a process that can be modeled as approximately linear or piecewise linear. The general tuning methodology is developed by extending the concepts of gain and phase margin from classical control. It is illustrated using a fuzzy proportional feedback controller with feedforward compensation. The paper shows that the key tuning parameter for stability is the ratio of the universe of discourse for the error input and the universe of discourse for the control output.