Backstepping Sliding Mode Control for NSVs with Disturbance Observer

In this paper, to deal with the uncertain disturbances of near-space vehicles (NSVs), a new disturbance observer based on terminal sliding mode (TSMDO) technique and an adaptive backstepping sliding mode control scheme with the TSMDO are developed. The TSMDO can estimate the unknown external disturbances and the modeling uncertainties within the finite time and the differentiator is employed to avoid differential expansion problems in the backstepping control design. The rigorous stability of the closed-loop system is proved with Lyapunov method. Finally, simulation results illustrate that the proposed control scheme based on TSMDO can guarantee the satisfactory tracking performance of the multi-input and multi- output (MIMO) attitude motion for the NSV under the external unknown disturbance.