Autonomous rendezvous and docking with tumbling, uncooperative, and fragile targets under uncertain knowledge

Abstract

As efforts to expand humanity's presence in space continue to increase, a need for spacecraft to autonomously perform in-space close proximity maneuvers without a human operator increases, as well. Such in-space close proximity maneuvers include active debris removal, satellite servicing, and in-space assembly. Active debris removal will facilitate the continued use and access to low Earth orbit, mitigating the exponential debris growth occurring due to decrepit satellites and rocket bodies colliding. Satellite servicing will provide the capability to repair and refurbish spacecraft, elongating the lifetime of valuable assets both locally orbiting Earth and on routes further out in the solar system. In-space assembly is the means by which large space structures are developed in orbit. Currently, such feats occur with the help of astronauts and robotic arms (i.e. the continued development of the International Space Station). However, for increased benefit, in-space assembly must occur autonomously, without a human in-the-loop, in order to create large structures in locations unideal for humans or with a non-negligible communication latency. These three reference missions need the software enabling autonomous rendezvous and docking to reach a technical readiness level to be employed with confidence. In-space close proximity maneuvers share a standard sequence of events described in this thesis. The focus of this thesis address the terminal approach trajectory to soft docking, the contact dynamics of docking between two spacecraft, the optimization of the detumble procedure to bring the Target to stabilization, and adaptive control techniques to handle uncertainties in spacecraft knowledge. The software developed in support of these subproblems is included in the appendices and is largely based on implementation with the Synchronized Position Hold Engage Reorient Experimental Satellites (SPHERES) platform or with the characteristics of SPHERES considered.