Design of fractional-order backstepping sliding mode controller for the quadrotor unmanned aerial vehicles

This paper proposes a fractional-order controller based on backstepping control method and sliding mode control technique for four-rotor unmanned aerial vehicle (UAV). As it is known that the quadrotor UAV is a complex, second-order system which is also nonlinear, coupled and even under-actuated. With the help of Newton-Euler formula, the dynamics can be clearly expressed in mathematical form. Then the backstepping control method is used in controller design firstly. Secondly, the sliding mode control technique with fractional-order operator is added to improve the robustness and anti-interference ability of system. Next, the fractional-order theory is used to eliminate the chatter brought by the sliding mode control. Finally, simulation results are applied to demonstrate the validity of the controller.