Double line-of-sight measuring relative navigation for spacecraft autonomous rendezvous

摘要

This paper presents a double line-of-sight (LOS) measuring relative navigation technique for far or medium range (tens of kilometers ～ several kilometers) autonomous rendezvous. In this new relative navigation technique, two chase spacecraft with inter-spacecraft crosslink form a measuring baseline relative to the target spacecraft in space and, respectively, measure LOS angles of the target and their own inertial states. The processing noise model of the relative navigation system is developed based on the spacecraft relative dynamics equations described in inertial frame. The measurement model including LOS angles of the target and the bearing and length of the measuring baseline is established. A discrete-time extended Kalman filter (EKF) is developed to estimate the relative motion of the target. The degree of observability of the navigation system is analyzed by the condition number. Numerical simulation results indicate that: (1) the relative position and velocity of the target can be estimated with sufficient accuracy using the double LOS measuring relative navigation technique, (2) compared with that of single LOS angles-only navigation, the observability of double LOS measuring relative navigation is improved, (3) the separation angle between two LOS vectors influences the estimation errors and the observability of the navigation system.