Abstract: The adaptive backstepping approach based on turning function is improved in this paper. A new robust adaptive flight control system is designed for a certain unmanned aerial vehicle (UAV). First, the system model of the UAV is changed to a disturbed strict feedback system, which contains nonlinear parameter uncertainty, uncertain nonlinear and unmodeled dynamics. Second, a Lyapunov function with an adaptive regulating term to the general error is presented and then a stable adaptive control law and parameter update law is derived. There is a robust adaptive term, which can compensate the effect of uncertain nonlinear and the unmodeled dynamics both in the control law and parameter update law. The adaptive regulating term to the general error also appears in the control law and parameter update law, its main function is to slow the parameter update rate when the actuator saturation occurs. At last, this new flight control system is tested by simulation.

Key words: robust, adaptive control, backstepping, unmanned aerial vehicle, flight control