Disturbance observer-based adaptive sliding mode control for near-space vehicles

In this paper, a new sliding mode disturbance observer (SMDO) is developed using the terminal sliding mode technique. The SMDO is employed to estimate unknown external disturbances and modeling uncertainties in finite time. Based on the designed SMDO, a boundary layer adaptive sliding mode attitude control scheme is proposed for near-space vehicles (NSVs). The designed attitude control scheme can guarantee the satisfactory attitude tracking performance of the multi-input and multi-output (MIMO) attitude motion for the NSV subject to the time-varying disturbance. The rigorous stability of the closed-loop system is proved using the Lyapunov method. Finally, simulation results are presented to illustrate the effectiveness the proposed control scheme.