Active Fault-Tolerant Control of the Quadrotor System Based on Adaptive Sliding Mode Observer

In this paper, the fault-tolerant control is investigated of a quadrotor UAV under sensor and actuator faults and external disturbance. Since the quadrotor UAV is underactuated, it is divided into two subsystems: altitude and attitude subsystem and horizontal position subsystem. Then the actuator and sensor faults are used as auxiliary states to augment the system state. For the augmented system, the adaptive sliding mode observer (ASMO) is proposed to estimate the faults and the system states without the restrictive assumption that the bounds of faults are known. Therefore, the update laws are proposed in order to estimate the unknown bounds of faults. In addition, the H<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</inf> performance index and fault-tolerant controller are proposed in order to improve the robustness of the quadrotor UAV. Finally, the numerical simulation is carried out using the quadrotor dynamic model to verify the effectiveness of the fault-tolerant method.