Attitude control for flying wing unmanned aerial vehicles based on fractional order integral sliding-mode

For the attitude control of flying wing unmanned aerial vehicles (UAV) with unknown external disturbances, an attitude tracking control scheme based on fractional order integral sliding mode and dual power reaching law is proposed. Combining fractional order calculus with sliding-mode variable structure control theory, we design a fractional order integral sliding surface. To tackle the problems of long convergence time and serious buffeting of traditional reaching law, we propose a dual power reaching law with second order sliding-mode properties and finite time convergence. Together with the nominal sliding-mode control law, a super twisting sliding-mode disturbance observer is designed to estimate and compensate for disturbances, which improve both the robustness and control performance of the control system. To take full advantage of the redundant control surfaces and improve the nonlinear control efficiency, the nonlinear control allocation is applied in the flight control system. Simulation results show the effectiveness of the proposed control scheme.