Robust Adaptive Fuzzy Control for a Class of MIMO Nonlinear Systems with Unknown Dead-Zones and Gain Signs

In this paper, adaptive fuzzy control is proposed for a class of uncertain MIMO nonlinear systems with unknown dead-zones and a triangular control structure. The design is based on the principle of sliding mode control and the property of Nussbaum function. The approach does not require a priori knowledge of the sign of the control gain and the upper bound and lower bound of dead zone model parameter to be known a priori. The adaptive compensation for the optimal approximation error is employed to minimize the influence of modeling errors and parameter estimation errors. By theoretical analysis, the closed-loop control system is proved to be stable in the sense that all signals involved are bounded, with tracking errors converging to zero. Simulation results demonstrate the effectiveness of the approach