Robust Adaptive Fuzzy Control of MIMO Nonlinear Systems with Higher-Order and Unmatched Uncertainties

In this paper, a robust adaptive fuzzy controller is designed for the output tracking control problem of multi-input multi-output (MIMO) nonlinear systems with higher-order and unmatched uncertainties. For real mechanical systems, the strength of the unmatched uncertainties is bounded by the pth-order polynomials in states, in contrast to other works assuming that these uncertainties are bounded by the first-order polynomials in states. Based on the combination of the optimal control with fuzzy systems and some feasible adaptation laws, the proposed robust adaptive fuzzy controller can not only guarantee that all the signals in the whole closed-loop systems are bounded, but also obtain that the output tracking performance of MIMO nonlinear uncertain systems is well established. A series of computer simulations are illustrated to demonstrate the validity of the proposed control scheme.