Fuzzy based adaptive dynamic surface control for a class of uncertain nonlinear systems in strict-feedback form

This paper provides a simplified design scheme for the control of a class of nonlinear systems in strict-feedback form by incorporating dynamic surface control (DSC) method into an adaptive fuzzy logic system. The DSC method overcomes the problem of ldquoexplosion of complexityrdquo in the traditional backstepping design. Fuzzy logic system (FLS) is used to approximate the nonlinear uncertainty. Adaptation law adjusts those fuzzy parameters online to minimize the approximation error. This new scheme not only eliminates the problem of explosion of complexity in backstepping scheme, but also guarantees the semi-global uniform boundedness of the solution of the closed-loop system, and makes the tracking error converge to a small residual set. Simulation results illustrate that the new scheme is effective.