Observer-based adaptive fuzzy funnel control for strict-feedback nonlinear systems with unknown control coefficients

This paper proposes an adaptive fuzzy funnel controller for a class of strict-feedback nonlinear systems with unknown control coefficients. A fuzzy state observer is designed to estimate the unmeasurable system states. An improved funnel error is given and embedded in the procedure of control design. Furthermore, based on the backstepping method, an observer-based adaptive fuzzy funnel controller is constructed, which can guarantee that the output tracking error remains in a pre-set funnel and converges to a prescribed interval in finite time as long as the initial error is in the funnel. All the signals in the closed-loop system are also semi-globally uniformly and ultimately bounded. Simulation results demonstrate the effectiveness of the developed controller. (C) 2019 Elsevier B.V. All rights reserved.