Precise Angles-Only Navigation for Noncooperative Proximity Operation with Application to Tethered Space Robot

For microspacecraft that have limited payload capability, the potential use of vision sensors (e.g., cameras) has been already recognized in noncooperative proximity operation. However, vision-based relative navigation is difficult, because vision sensors have the limitation to accurately measure distance information. In this paper, we propose an angles-only navigation and control framework for noncooperative proximity operation. The framework is especially suitable for challenging long-range proximity operation, where only the line-of-sight angles of the target can be obtained. Within the proposed framework, the spacecraft not only estimates its current orbital position precisely with only angle measurements but also approaches to a noncooperative target by following desired attitude and orbital motions. The framework combines an off-line motion planning and an online navigation and control that is based on model predictive control (MPC) and time delay control (TDC). The study is with application to tethered space robot. Extensive simulations illustrate the effectiveness of the proposed framework.