Robust backstepping sliding mode control for coaxial tilt-rotor UAV

This paper investigates the problem of the modeling and robust control for a new coaxial tilt-rotor unmanned aerial vehicle (CTRUAV). The CTRUAV is composed of two pairs of coaxial tilted rotors at the front and one rotor at the tail. The dynamic model of CTRUAV is established on the basis of Newton-Euler formulas, and a robust adaptive backstepping sliding mode controller is proposed to realize the motion control of the CTRUAV under external disturbances. The controller includes two sub-controllers: an inner loop attitude controller based on adaptive backstepping sliding mode control and an outer loop position controller based on backstepping method, which guarantees that the closed-loop system is asymptotically stable. Finally, simulations are given to demonstrate the effectiveness of the designed controller.