Robust disturbance rejection guidance law for autonomous rendezvous with tumbling non-cooperative spacecraft

A robust disturbance rejection guidance law for autonomous rendezvous with non-cooperative target is studied using generalized super-twisting algorithm (GSTA) and homogeneous high order sliding mode observer (HHOSMO). The proposed method is able to ensure a service spacecraft subject to modeling uncertainties, external disturbances and actuator/thruster failures accomplishes the rendezvous mission without collision. Considering the restriction of Clohessy-Wiltshire (C-W) equations, a coupled relative motion model is established in line of sight coordinate frame. The GSTA is used as a robust continuous guidance law while the HHOSMO is able to observe and compensate the lumped disturbances in a finite time to enhance the ability of disturbance rejection. The stability of the closed-loop system is analyzed using Lyapunov stability criteria. Results obtained from numerical simulations demonstrate the validity of the method formulated in this paper.