Safely flying strategy of space robot for approaching a tumbling satellite

In order to capture and rescue a tumbling satellite, a space robot is required to plan an appropriate path to approach the target satellite in limited time and avoid collisions in the approaching path. This paper focuses on the safely flying strategy for space robot approaching a tumbling target satellite. First, kinematic models of space robot and target satellite are built to parameterize their geometric envelopes and obtain the relative motion equations between them. Then, two safely flying strategies are developed, including the definitions of safely capturing corridors, the selections of straight paths as well as the orbit and attitude control strategies of space robot in different approaching phases. Furthermore, the capabilities of the two strategies are analyzed through a numerical simulation. The results illustrate that both the two strategies are effective for the mission of approaching a tumbling satellite. Finally, the comparison between the two strategies is made and the strategy selection criterion is summarized as conclusions.