Trajectory tracking of tail-sitter aircraft by ℓ₁adaptive fault tolerant control

This paper proposes an ℓ1 adaptive fault tolerant control method for trajectory tracking of tail-sitter aircraft in the state of motor loss fault. The tail-sitter model considers the uncertainties produced by the features of nonlinearities and couplings which cause difficulties in control. An ℓ1 adaptive controller is designed to reduce the position and attitude error when actuators have faults. A reference trajectory containing large maneuver flight transitions is designed, which makes it even harder for the ℓ1 controller to track accurately. Compensators are designed to assist ℓ1 adaptive controller tracking of the reference trajectory. The stability of the ℓ1 adaptive controller including compensators is proved. Finally, the simulation results are used to analyse the effectiveness of the proposed controller. Compared to the H∞ controller, the ℓ1 adaptive controller with compensators has better performance in position control and attitude control under fault tolerance state even when the aircraft conducts large maneuver. Besides, as the ℓ1 adaptive control method separates feedback control and adaptive law design, the response speed of the whole system is improved.