L1 Adaptive fuzzy controller for a class of nonlinear systems with unknown backlash-like hysteresis

This paper proposes an adaptive fuzzy logic control scheme for a class of strict-feedback nonlinear systems with unknown backlash-like hysteresis. The proposed controller exploits the properties of the newly developed L-1 adaptive control in conjunction with the approximation capability of fuzzy systems. The developed controller is fast, the adaptation can be as fast as the CPU permits, and robust by virtue of the L-1 adaptive control structure and the direct estimation of the system nonlinear functions via fuzzy logic systems. As a result, the proposed L-1 adaptive fuzzy controller has a simpler form and requires fewer adaptation parameters. The inverted pendulum and Duffing forced oscillation systems are used in simulation studies to verify the effectiveness of the proposed L-1 adaptive fuzzy control scheme.