Robust trajectory tracking control for a quadrotor unmanned aerial vehicle using disturbance observer

In this paper, a robust trajectory tracking control strategy using disturbance observer is developed for a quadrotor Unmanned Aerial Vehicle (UAV) in the presence of external aerodynamic disturbance. Considering the external aerodynamic disturbance force, a backstepping control scheme is designed for the position subsystem to ensure that the quadrotor UAV can track the reference position signal rapidly. In order to obtain the strong robustness, nonlinear disturbance observers are introduced to the position control and attitude control, which are used to estimate the unknown aerodynamic disturbances. The simulation results show that the proposed control strategy can make the quadrotor UAV track position signal and yaw angle signal quickly and smoothly with guaranteeing the stability of roll angle and pitch angle, which has strong robustness to external disturbance.