FUZZY REGULATORS AND FUZZY OBSERVERS - RELAXED STABILITY CONDITIONS AND LMI-BASED DESIGNS

This paper presents new relaxed stability conditions and LMI- (linear matrix inequality) based designs for both continuous and discrete fuzz y control systems. They are applied to design problems of fuzzy regula tors and fuzzy observers, First, Takagi and Sugeno's fuzzy models and some stability results are recalled. To design fuzzy regulators and fu zzy observers, nonlinear systems are represented by Takagi-Sugeno's (T -S) fuzzy models, The concept of parallel distributed compensation is employed to design fuzzy regulators and fuzzy observers from the TS fu zzy models. New stability conditions are obtained by relaxing the stab ility conditions derived in previous papers, LMI-based design procedur es for fuzzy regulators and fuzzy observers are constructed using the parallel distributed compensation and the relaxed stability conditions . Other LMI's with respect to decay rate and constraints on control in put and output are also derived and utilized in the design procedures. Design examples for nonlinear systems demonstrate the utility of the relaxed stability conditions and the LMI-based design procedures.