Fuzzy observer-based control of nonlinear systems

In this paper, some recent results on systematic design of model based fuzzy controllers for nonlinear systems with Takagi-Sugeno (T-S) fuzzy models are discussed. These methods are based on finding a common Lyapunov matrix and state feedback gains for the closed loop T-S fuzzy model using linear matrix inequalities. However, all of these methods assume that the states are available for measurement, while in reality this is not the case. To solve this problem, the notion of fuzzy observer is introduced and a separation theorem for the observer/controller system is stated and proof sketch is presented