Observer Based Robust Trajectory Tracking Control for a Tilt Trirotor UAV

In this paper, an observer based robust trajectory tracking control scheme is proposed for a tilt trirotor unmanned aerial vehicle (UAV). The UAV’s system is divided into two subsystems denoted as the position subsystem and the attitude subsystem. As the tilt trirotor UAV is a typical underactuated system, a new backstepping based nonlinear robust controller is developed to let the tilt trirotor UAV track a desired position trajectory. To compensate the unknown external disturbances, an finite-time convergence disturbance observer is also designed for the attitude loop control. Lyapunov based stability analysis is employed to prove the asymptotic convergence of the position tracking errors and the stability of the closed-loop system. Numerical simulation results are provided to validate the good tracking performance of the proposed control strategy.