Feedforward plus feedback fuzzy robust tracking control for a class of uncertain nonlinear systems

This paper presents a novel fuzzy tracking control method for the tracking problem of uncertain nonlinear systems. Based on T-S (Takagi-Sugeno) fuzzy description of uncertain nonlinear dynamics, the tracking error is studied. Without the need for augmented system, exponential stability of the tracking error can be obtained by a fuzzy feedforward controller. The main advantage lies in eliminating the demand for dimension increase, and reducing the conservativeness of methods involving an augmented disturbance. Another contribution of this work is that good performance of the tracking controller can be achieved by using H-infinity control and disk pole placement. The solutions to the robust fuzzy tracking controller can be obtained by applying linear matrix inequality tool and fuzzy logic theory. Simulation results demonstrate that the fuzzy feedforward control based technique can greatly improve the tracking speed and robust performance.