A novel angles-only relative navigation algorithm for space non-cooperative target on-orbit servicing

The theory substance of angles-only relative navigation for autonomous orbital rendezvous to non-cooperative target is discussed. A novel algorithm based on GPS absolute positioning and CCD relative angles of LOS measuring is presented, which is aided by an initial value of the relative distance including error from ground or space surveillance system only once. Emphasis is placed on the relative distance reconstruction and angles-only navigation filter development to determine relative position and velocity between a passive non-cooperative target and a maneuvering servicer. A recursive estimation formula of relative distance is derived from the differential value between the sequences of GPS positioning at two different epochs, based on triangle principle, while the recursive errors are analyzed by theoretical derivation and numerical simulation. Then the navigation filter model is established, and an Extended Kalman filter is selected to process angular measurements from a CCD camera along with relative distance obtained recursively from GPS to estimate the relative states. The proposed algorithm is systemically tested by numerical simulation, and robustness about the error of initial relative distance value aided is evaluated.