Backstepping Terminal Sliding Mode for Flight Control Based on Nonlinear Disturbance Observer

A backstepping terminal sliding mode control scheme based on nonlinear disturbance observer(NDO) is proposed in the presence of model nonlinearity,aerodynamic parameter and moment disturbance uncertainties for maneuvers flight.The control scheme removes the priori condition of the upper bound of uncertainties by using NDO to approximate uncertainties.Explosion of complexity is avoided by combining dynamic surface control with the design virtual controller.A fast terminal sliding mode control strategy is then used to improve convergence and steady-state tracking accuracy of the system.Using the Lyapunov stability theorem,all signals in the closed loop system are guaranteed to be ultimately uniformly bounded.Simulation of a nonlinear six-degree-of-freedom maneuvering flight of an aircraft is done.The results show effectiveness of the proposed control scheme.