Robust integrated translational and rotational control for spacecraft rendezvous in unstructured environments

Abstract

The problem considered in this paper is the robust integrated translation and rotation control for spacecraft rendezvous in unstructured environments. The pursuer spacecraft considered is equipped with a single main thruster, capable of only providing thrust along one axis of the body frame, and attitude control actuators, capable of providing manoeuvrability in three axes of the body frame. The formulated coupled translational and rotational dynamics of the spacecraft with various uncertainties performs an under-actuated highly nonlinear system. A technical state transformation is then proposed to transform the coupled dynamics into a cascaded nonlinear system with the first subsystem being a linear perturbed system. This special cascaded nonlinear structure inspires the synthesization of the eigenstructure assignment parametric technique and the backstepping philosophy to guarantee not only robust closed-loop stability but also a robust trajectory tracking performance in the presence of various system uncertainties coming from unstructured environments. Moreover, rigorous closed-loop stability analysis is undertaken by using singular perturbation theory. Finally, a space interception is used to demonstrate the effectiveness of the proposed control scheme.