Global asymptotic fault-tolerant tracking for time-varying nonlinear complex systems with prescribed performance

Abstract

This paper investigates the global adaptive asymptotic fault-tolerant control of time-varying complex nonlinear systems with prescribed performance. The considered system simultaneously involves both mismatched intrinsic unknown time-varying parameters and nonvanishing external disturbances as well as possible actuator faults, which make the underlying problem challenging. By introducing a special kind of funnel functions, together with fusing a barrier Lyapunov function technique and a bound estimation approach, a novel prescribed performance fault-tolerant control scheme is proposed, which, as compared with the existing results, exhibits the following appealing features: (1) it is capable of dealing with nonlinear systems with high relative degree and serious unmatched time-varying uncertainties; (2) it can guarantee a global prescribed transient performance such that the performance specifications in terms of settling time and the tracking accuracy can be off-line preassigned according to task requirements, without dependence on initial conditions and any design parameters; (3) it can realize asymptotic output tracking, where no knowledge about the high-order derivatives of the reference trajectory is required. In the end, a simulation example is provided to attest the efficiency of the designed scheme.