A Composite Adaptive Fault-Tolerant Attitude Control for a Quadrotor UAV with Multiple Uncertainties

In this paper, a composite adaptive fault-tolerant control strategy is proposed for a quadrotor unmanned aerial vehicle (UAV) to simultaneously compensate actuator faults, model uncertainties and external disturbances. By assuming knowledge of the bounds on external disturbances, a baseline sliding mode control is first designed to achieve the desired system tracking performance and retain insensitive to disturbances. Then, regarding actuator faults and model uncertainties of the quadrotor UAV, neural adaptive control schemes are constructed and incorporated into the baseline sliding mode control to deal with them. Moreover, in terms of unknown external disturbances, a disturbance observer is designed and synthesized with the control law to further improve the robustness of the proposed control strategy. Finally, a series of comparative simulation tests are conducted to validate the effectiveness of the proposed control strategy where a quadrotor UAV is subject to inertial moment variations and different level of actuator faults. The capabilities and advantages of the proposed control strategy are confirmed and verified by simulation results.