Collaborative Untethered Transport of Free-Floating Objects in Microgravity : A Rendezvous-Based Planning and Control Framework

Sammanfattning

Collaborative transport of passive objects in microgravity is a key capability for emerging space applications such as on-orbit servicing, debris removal, and in-space assembly. Traditional approaches largely rely on rigid connections, which typically require dedicated infrastructure to be present on the object, or on manipulators, in which the robot and object are mechanically coupled before transport commences. Such methods are typically costly and limited in scalability and reusability, as they require precise and often complex docking procedures prior to transport. More recently, impact-based approaches have been proposed to enable untethered collaborative transport, eliminating the need for rigid attachments. This thesis presents a formal planning and control framework for untethered collaborative transport of a free-floating, non-cooperative object in microgravity. The proposed method replaces impulsive interactions with rendezvous-preceded, untethered contacts, enabling gentle momentum transfer while maintaining stability and safety. High-level task requirements and safety constraints are formally specified using Signal Temporal Logic and encoded into a Mixed-Integer Convex Programming problem. The resulting framework follows a hierarchical structure consisting of a Mixed-Integer Programming–based offline planner, an online re-planner that enforces geometric feasibility, and a Model Predictive Control layer for trajectory tracking and interaction execution. The approach is evaluated in a two-dimensional microgravity analogue environment using high-fidelity simulations of free-flying robots and objects. The results indicate that rendezvous-based interactions enable collaborative, untethered transport with low interaction forces and adequate accuracy over short- to medium-duration planning horizons. Beyond demonstrating feasibility, the proposed framework provides a systematic way to formally specify, plan, and execute untethered interactions in two-dimensional microgravity analogue environments, supporting future autonomous space operations. Code and videos are available at https://arian-koura ngi.github.io/DA236X-Master-Thesis/