Abstract: A back-stepping-fault-tolerant control is proposed for keeping the formation of leader-follower unmanned aerial vehicles(UAV) under the conditions of actuator fault, uncertain aerodynamic parameters and external disturbance. The forward, lateral and altitude distance error models are described. An UAV motion model with actuator fault, external disturbance, and uncertain aerodynamic parameters is described. An inner loop fault-tolerant control system is designed to track the command signal produced by the outer loop formation controller. The inner loop fault-tolerant control system is consisted of three parts:one is the fault detection and identification (FDI) mechanism to locate the fault actuator and estimate the fault parameters; one combines back-stepping control with fault parameters and an adaptive disturbance observer to compensate for actuator faults, external disturbance, and uncertain aerodynamic parameters; the other one is the stability analysis of the inner loop controller system. The simulated results show that the proposed control method can be used for the fault-tolerant control of UAV formation. Key

Key words: unmannedaerialvehicleformation, formationkeeping, leader-followerformation, actuatorfault, faultdetectionandidentification, back-stepping-fault-tolerantcontrol