Improving Contact Time in Active Debris Removal Interaction via Optimised Hybrid Compliance

The increasing population of uncooperative space debris in Low Earth Orbit (LEO) poses a significant risk to the sustainability of future space missions. The need for safe, robust and effective Active Debris Removal (ADR) strategies cannot be denied any more. This paper takes on the previous work on a small satellite novel hybrid-compliant two-stage mechanism, called the Soft Capture Unit (SCU), designed to enhance autonomous debris capture by enabling controlled energy-dissipative contact with flat-surfaced debris. This device must ensure enough contact time for its subsystem to be activated and adhere to the surface of the debris. To that extent, a dynamic state-space model of the designed system was developed, and an optimisation algorithm was implemented using experimental impact data collected in the University of Luxembourg's Zero-G lab. By systematically varying the compliant system's parameters, an optimised coefficient set of stiffness and damping was calculated to maximise contact duration under a representative impact velocity. Experimental tests emulating several mass factors show a contact time increase of at least +138.00 ms over a non-compliant configuration, significantly improving activation reliability and reducing risk-critical factors such as hard shocks for successful debris removal. These findings are validated through close-toreal scenarios testing, confirming the feasibility of the proposed mechanism for future ADR missions.