Command Filter Based Adaptive Fuzzy Control of Uncertain Deferred Constrained Nonlinear Systems With Actuator Fault and Dead Zone

In this article, the adaptive fuzzy fault-tolerant control (FTC) issue of a class of nonstrict feedback uncertain nonlinear systems with deferred asymmetric time-varying (DATV) full-state constraints, dead zone, actuator fault, unknown control directions and disturbances is discussed. To eliminate the restriction that the initial states of the system must be within the constraints, a new deferred constrained (DC) function is devised to prevail over the conservatism of time-varying asymmetric constraints (TVAC). To achieve state constraints and simplify design, a model transformation is formulated to transform constrained system into unrestricted system. The fuzzy logic systems (FLSs) are employed to approximate the uncertain nonlinear function. To handle “explosion of complexity” (EOC), the command filter is introduced to substitute the derivatives of the control laws. To tackle actuator fault, dead zone and unknown control directions, a FTC scheme is formulated using backstepping method and the Nussbaum-type function. Furthermore, it is theoretically proven that the formulated control method can ensure that all signals in system are bounded and the tracking error converges to a small neighborhood including the origin in a finite time. The reliability of the formulated control scheme is demonstrated by the simulation result of the robot manipulator system.