Observer-based robust control of uncertain fuzzy dynamic systems with pole placement constraints: an LMI approach

This paper investigates both analysis and synthesis techniques for robust pole placement in linear matrix inequality (LMI) regions involving observer-based fuzzy control. The class of systems considered here is the continuous Takagi-Sugeno (T-S) fuzzy model with parametric structured uncertainties and unavailable state variables. Sufficient global stability conditions are established which make it possible to robustly assign the closed-loop poles of the augmented system containing both the fuzzy controller and observer in the left half complex plane and also to guarantee control performances by imposing a pole placement. Because of uncertainties, the separation property is not applicable to design the fuzzy controller and observer separately. The idea of the proposed approach is to assign both state and estimation error poles to a desired LMI region and to use the H_infin technique in order to guarantee that the estimation error converges faster to the equilibrium point zero. An example is given to illustrate the effectiveness of the proposed approach