Dynamic Surface Attitude Tracking Control for a Quadrotor Using Disturbance Observer

In this paper, a dynamic surface control strategy based on disturbance observer is proposed to stabilize three attitude angles of a quadrotor unmanned aerial vehicle (UAV) in the presence of external disturbance. To compensate for external disturbance, a disturbance observer with exponential convergence is developed. Considering the problem of explosion of complexity in traditional backstepping control, a first-order low-pass filter is used to avoid repeated differentiation of virtual control signal. Based on the disturbance observer and the filter, a robust attitude dynamic surface trajectory tracking control technique is designed for a quadrotor. The convergence of disturbance observation error and tracking error is proved using Lyapunov theory. The comparative simulations are carried out to demonstrate the effectiveness of the proposed control scheme.