Prescribed-Time Sliding-Mode Fault-Tolerant Control for Quadrotor UAVs Based on Disturbance Observer

This paper mainly focuses on the prescribed-time attitude tracking problem of quadrotor unmanned aerial vehicles (QUAVs) with unknown disturbances and actuator faults. Firstly, a prescribed-time disturbance observer (PTDO) is designed based on the prescribed-time stability theorem to estimate the compound lumped disturbance consisting of unknown disturbances and actuator faults, and its prescribed-time stability is proved. Then, a PTDO-based prescribed-time fault-tolerant controller is designed by using the sliding mode control method. A sliding mode fault-tolerant controller is designed based on a prescribed-time sliding surface and reaching law, and its prescribed-time stability is analyzed and proved. The controller aims to achieve the convergence of attitude tracking errors for the QUAVs within a prescribed time in the presence of unknown disturbances and actuator faults. In addition, the convergence time of the controller is determined by simple prescribed-time parameters. The simulation results show that the proposed prescribed-time fault-tolerant control scheme is effective.