Fuzzy-model-based Control Systems Using Fuzzy Combination Techniques

This paper presents a fuzzy combined model and a fuzzy combined controller to handle nonlinear systems. A fuzzy combination of some local fuzzy models is employed to represent a nonlinear system. Based on this fuzzy combined model, a fuzzy controller combining some local fuzzy controllers is proposed to control the nonlinear system. Conditions are derived to guarantee the system stability. By using the fuzzy combination technique, the stability analysis is reduced to investigating only the stability of the local fuzzy control systems. The system that combines the local fuzzy systems will then be guaranteed stable. This property reduces the difficulty of finding the solution to the stability conditions even though the fuzzy combined model has effectively distributed the complex nonlinearity over the local fuzzy models. Furthermore, any sharp changes in the system states and control signals caused by the switching activities between local fuzzy control systems are smoothed out by the fuzzy combined controller. An application example will be given to show the merits of the proposed approach.