Finite-time control based on the time-varying sliding mode for spacecraft body-fixed hovering over an asteroid

This paper investigates a finite time control for spacecraft hovering in highly uncertain dynamical environments, typically found around asteroids. The control method is based on the time varying second order sliding mode control. Firstly, feedback linearization is exploited to transform the dynamic equations for spacecraft into three independent second order uncertain subsystems. Secondly, a simplified model of the natural elongated body is introduced to describe its gravitational field. The proposed control scheme for the hovering maneuvers is proved with a stability analysis. Finally, numerical simulations are performed to evaluate the effectiveness of the proposed control scheme.