Fuzzy Controller Design Based on the Phase Plane Isoclines

In this paper we describe a procedure that exploits geometric properties of state space in the investigation of the system stability. Although this method is cumbersome, its practical value becomes clear in the situation when state space is reduced to a phase plane, which is the case in a second-order system. Then phase plane analysis offers well known procedures (especially in case f(.) is linear) for the determination of the system stability. Simulation results, obtained by implementation of the proposed method on the fuzzy controller design, are given at the end of the paper