Elliptical Orbital Spacecraft Rendezvous without Velocity Measurement

This paper presents a new robust output feedback guidance scheme for autonomous spacecraft rendezvous during the final phase in elliptical orbit. The proposed approach is essentially a compound control method, which consists of an input-to-state stable (ISS) concept and high-gain observer (HGO) methodology. More specifically, the HGO is used to estimate the relative velocity between two neighboring spacecrafts, while the ISS-based controller is used to regulate the relative position and the relative velocity to a small region around zero asymptotically. Stability analysis of the closed-loop system is also established by using Lyapunov theory. Numerical simulations are performed to demonstrate the robustness and effectiveness of the proposed method.