Abstract:

A robust sliding mode control law of trajectory tracking is described and demonstrated for the coupled and under-actuated aircraft longitudinal dynamic model. Firstly, by introducing a virtual state variable, the state counterchange is applied to realize the control decoupling. Secondly, a nonlinear disturbance observer (NDO) is proposed for the compensation of system uncertainty which consists of modeling error and atmosphere disturbance. Thirdly, the curves of angle of attack (AOA) and the virtual state variable during extremely short takeoff and landing (ESTOL) are set up, which are treated as the tracking trajectories of the designed sliding mode control law. Finally, the simulation results are given, which demonstrates that the proposed NDO can realize accurate estimation and compensation of system uncertainty, as well as that the designed control law can be effectively applied to longitudinal trajectory tracking of AOA against system modeling error and atmosphere disturbance.