Output-feedback adaptive fuzzy control for a class of nonlinear systems with input delay and unknown control directions

In this paper, an adaptive fuzzy control scheme is proposed for a class of nonlinear systems with input delay, unknown time-varying delays and disturbances via dynamic output-feedback approach. During the controller design procedure, the input delay is dealt with by combining the smoothed dead-zone approach with the integral mean value theorem. Moreover, fuzzy logic systems (FLS) are employed to approximate the unknown continuous functions. The main advantages of this paper are that (1) the output-feedback adaptive fuzzy controller can dispose a class of nonlinear time-varying delay systems with input delay, in which the virtual control coefficients are all unknown and (2) only two parameters need to be adjusted online in controller design procedure, which reduces the online computation burden greatly. It is proven that the proposed control scheme renders the closed-loop system stable in the sense of semiglobal UUB. Finally, simulation results are provided to show the effectiveness of the proposed approach.