Fuzzy robust control for discrete-time nonlinear systems using input-output linearization and H∞ optimization

Deals with H_∞ control for discrete-time nonlinear systems using an input-output linearization concept. Based on the ability of fuzzy systems to approximate any nonlinear mapping, the unknown nonlinear system is represented by a Takagi-Sugeno fuzzy model. The control problem is then tackled using a feedback linearization of the fuzzy nonlinear system. However, this feedback linearization can not guarantee robustness in the presence of uncertainties and disturbances. In order to solve this problem, an additive H_∞ control component is added to the linearizing controller to attenuate uncertainty and disturbance influence on the control performances. In the paper, the H_∞ control component is designed in terms of a modified Riccati inequality. Finally, an illustrative example is included to demonstrate the feasibility of the proposed method.