On the Observability for Visual-LiDAR 3D Sensing of Noncooperative Space Targets

Observability is an essential aspect for the performance of optical 3D sensing of noncooperative space targets. This paper provides a new perspective from statistical information to investigate the observability of space-based visual-LiDAR 3D sensing of space target. In particular, we first propose a Fisher information matrix (FIM)-based metric to evaluate observability. Then we give all the unobservable directions in state space for the visual-only, the LiDAR-only and the visual-LiDAR fusion methods, together with physical interpretations. Besides, it is proved that multisource fusion and multi-point sensing help improve sensing performance, and the influence of spacecraft pose, target pose/structure and their couplings on observability are also determined quantitatively. Numerical results validate our conclusions.