Fault-Tolerant Control for Autonomous Aerial Refueling against Actuator Fault in Receiver UAV ^⁎

This paper investigates the fault-tolerant control problem of a receiver unmanned aerial vehicle (UAV) against actuator fault and wake vortex induced by the tanker aircraft under the aerial refueling formation flight conditions. In autonomous aerial refueling (AAR), the relative distance of the receiver UAV with respect to the tanker aircraft/UAV is essential for the flight safety of the receiver UAV and the tanker aircraft/UAV. To design the fault-tolerant controller for the receiver UAV, disturbance observer technique is used to estimate the lumped uncertainties including wake vortex and actuator fault. Based on the estimated lumped uncertainties, backstepping architecture is utilized to construct the control scheme. Furthermore, it is shown that the relative forward distance and the relative perpendicular distance tracking errors are uniformly ultimately bounded. Finally, simulations are presented to show the effectiveness of the proposed fault-tolerant control scheme.