Precise method for relative navigation of a target satellite on non-coplanar elliptical orbit

We present a precise method for relative navigation between an on-orbit servicing micro-satellite and a target spacecraft on non-coplanar elliptical orbit. First, a mathematical model was established as the state equation. Such a model is more precise than the widely-used CW equations and can be applied to elliptical reference orbit. Then the measurement geometry was analyzed and measurement equation was set up. Unscented Kalman filter was chosen as the relative navigation filter. Simulation results show that our method performs very well and high precision estimation of relative position and velocity are achieved.