Nonsingular fixed-time fault-tolerant attitude control for tailless flying wing aircraft with time-varying flight envelope constraints

Abstract

This article investigates the fault-tolerant attitude control problem for the tailless flying wing aircraft subject to time-varying flight envelope constraints in the presence of the matched/mismatched disturbance, uncertain parameters, and time-varying actuator failures. To handle these problems and improve the convergence rate of the attitude control system, a nonsingular fixed-time convergent robust fault-tolerant control methodology is proposed. First, the time-varying barrier Lyapunov functions is introduced to confine the flight envelope within the predefined time-varying compact set while ensuring the transient performance of the attitude tracking error. Subsequently, the fixed-time sliding mode observer is designed to compensate for the matched/mismatched disturbance, uncertainties, and time-varying actuator failures, meanwhile, by introducing an intermediate control law in the attitude controller, the singularity problem is avoided without utilizing any filters or continuous and differentiable piecewise functions. Further, it has been analytically proved that all signals of the closed-loop system are bounded and converge to the residual set around the origin in a fixed time. Finally, simulations are conducted to illustrate the superiorities of the proposed scheme.