Robust Control Design for Quadrotor Trajectory Path Tracking

This paper deals with the tracking control problem of a quadrotor system in presence of uncertain system parameter due to unknown payload mass. To compensate for this disturbance, an integral backstepping controller is developed for this nonlinear system. Hence, based on backstepping techniques, an outer loop is firstly designed for translational tracking control. Then, without using simplified dynamics or small angle assumption, the references for attitude angles are derived using the coupled-state between (lateral, longitudinal) positions and (roll, pitch) Euler angles, which allows getting suitable trajectory references to the auxiliary inner loop designed for rotational tracking objective. The analysis of the control system stability is carried out using Lyapunov approach, and shows that the overall closed loop stability is guaranteed and that the proposed control laws yield asymptotic tracking for translational as well as for rotational quadrotor motions. A simulation example also shows that the proposed control strategy is able to stabilize the system along with perfect trajectory tracking performances, in spite of unknown payload mass.