Adaptive fault-tolerant flight control for a quadrotor UAV with slung payload and varying COG

Most of the existing quadrotor control strategies assume that the center of gravity (COG) coincides with the geometric center and remains unchanged. However, for a quadrotor UAV with payload, especially the slung payload, the spherical oscillation of the load during the flight will inevitably lead to the varying COG for a quadrotor UAV and affect the stability of attitude controllers which designed based on the assumption without COG variation. Aiming at the time-varying COG and unknown external disturbance, an adaptive fault-tolerant control method for quadrotor is proposed in this paper. A new quadrotor dynamic model is established with slung payload and the time-varying COG. Then we design an adaptive fault-tolerant controller to ensure the uniformly ultimate bounds (UUB) stability of all signals in the closed-loop system. The simulation experiments are carried out to prove the effectiveness, adaptability and robustness of the proposed design method.