A Visual Relative Motion Estimation Method for Inner Formation Satellite*

The inner formation satellite is composed of an exterior satellite and an interior satellite enclosed in its internal cavity body. The inner satellite runs on a pure gravitational orbit, which has special application prospects in the field of space science. However, due to non-conservative perturbation forces, relative orbit motion between inner and outer satellites would occur. In order to avoid collisions, relative orbit control must be implemented for the outer satellite, and relative motion estimation is one of the key links in control. This article proposed a vision-based method for estimating the relative motion of inner formation satellite. Firstly, the dynamic equation of relative orbital motion of inner formation satellite was established, and then a multi-camera-based measurement method was designed. The motion state estimation model was obtained based on the projection information of feature point on the image plane, and the relative motion state of inner and outer satellites is obtained using the unscented Kalman filterer. The simulation results show that this method can accurately obtain the relative orbit motion state of inner and outer satellites, and can provide effective measurement data for relative motion control.