Fixed-Time Antisaturation Cooperative Control for Networked Fixed-Wing Unmanned Aerial Vehicles Considering Actuator Failures

This article proposes a distributed fixed-time fault-tolerant control methodology for networked six-degree-of-freedom fixed-wing unmanned aerial vehicles (UAVs) whose models are subjected to actuator faults and saturation. Two fixed-time antisaturation control strategies are developed for velocity and attitude channels. Notably, the adverse effects of actuator faults (e.g., lock-in-place and loss of effectiveness) and actuator saturation can be effectively compensated for by means of a new adaptive-gain-based design. This feature differs significantly from most of the existing fault-tolerant control schemes. A fixed-time-based sliding-mode surface is delicately embedded in the control design in order to provide the attitude channel with the fixed-time tracking property. Model uncertainties and external disturbances can be effectively handled by using a bound estimation method and smooth functions. On the basis of Lyapunov stability theory, the closed-loop system is shown to be stable in the sense of the fixed-time concept. Actuator saturations are rigorously enforced, and the tracking errors of velocity and attitude converge to a residual set around the origin within a fixed time in spite of model uncertainties, external disturbances, and actuator faults. Numerical examples are carried out to validate the effectiveness of the theoretical findings.