Fuzzy output feedback control with almost disturbance decoupling for MIMO nonlinear systems

The problem of almost disturbance decoupling with internal stability is investigated for a class of MIMO nonlinear uncertain systems in nested lower triangular form. A fuzzy high-gain observer is designed to restructure the unmeasured states. Combining backstepping with the command filtered, fuzzy adaptive output feedback control design is proposed, the command filters introduced in this paper can overcome the problem of `explosion of complexity´ inherent in the traditional backstepping design. The proposed controller can not only achieve internal stability of the closed-loop system, but also diminish the effect of the disturbance on output in the sense of L₂ gain. Subsequently, simulation results are provided to show the effectiveness of the proposed approach.