Robust tracking control for nonlinear MIMO systems via fuzzy approaches

This paper addresses the problem of designing robust output tracking controls for a class of nonlinear MIMO systems that are represented by input-output models involving plant uncertainties and external disturbances. Hybrid adaptive-robust tracking control schemes which are based upon a combination of the H-infinity tracking theory, VSS control algorithm, and fuzzy control design are developed such that all the states and signals are bounded and an H-infinity tracking control is guaranteed. Consequently, the tracking performance of adaptive fuzzy-based control is greatly improved with the help of robust VSS and H-infinity control algorithms. The H-infinity tracking control design can be extended to treat general uncertain nonlinear systems with the help of adaptive fuzzy approximators. (C) 2000 Elsevier Science Ltd. All rights reserved.