Adaptive Output Feedback Tracking Control for a Class of Nonlinear Time-Varying State Constrained Systems With Fuzzy Dead-Zone Input

This paper proposes an adaptive fuzzy controller for a class of uncertain strict-feedback non-matching nonlinear single input single output (SISO) systems with fuzzy dead zone and full time-varying state constraints. The states considered here are immeasurable and full states of the systems are constrained in a bounded set with time-varying regions. Following the adaptive backstepping design framework, the tangent barrier Lyapunov functions (TBLFs) are introduced to the integrated design to address the problems in such systems. Fuzzy logic systems (FLSs) are used to identify the unknown smooth functions and unknown parameters. An input-driven observer is designed to estimate the immeasurable states. To distinguish the conventional deterministic dead zone models, the output of dead zone is uncertainty. The form of indeterminate dead zone as a combination of a liner and a disturbance-like term is extended by the fuzzy algorithms. Even though output of dead zone is fuzzy and adopting the integrated design, the proposed fuzzy controller can ensure that all the signals in the closed-loop systems are semi-global uniformly ultimately bounded (SUUB) and guarantee the tracking performance. Finally, simulation results are shown to verify the effectiveness and reliability of the proposed approach.