Observer-based fuzzy adaptive controller design for nonlinear systems with time-varying uncertain parameters

In this paper, we propose an observer-based fuzzy adaptive control scheme combined with state estimation for continuous-time multiple-input-multiple-output (MIMO) nonlinear systems with time-varying parametric uncertainties. The proposed observer-based fuzzy adaptive control employs a fuzzy system to approximate the time-varying parametric uncertainties, which are periodic and the only prior knowledge is the periodicity, where the tracking error can have fast parameter adaptation and fast convergence properties. Based on the Lyapunov stability theorem, the proposed fuzzy adaptive control system can guarantee the stability of the whole closed-loop system and obtain good tracking performance as well. Finally, the proposed method is applied to a 2-dof parallel robot control problems. The simulation can demonstrate the validity of the proposed scheme and achieve satisfy simulation results.