Results of the comrade project: combined control for robotic space- craft and manipulator in servicing missions: active debris removal and re-fuelling

Kurzfassung

The current space debris environment poses a safety hazard to operational space assets as well as a hazard to public safety and property in cases of uncontrolled re-entry events. The accidental 2009 satellite collision between Iridium-33 and Cosmos-2251 led to a debris cloud with up to 823 new large debris objects catalogued and many others not catalogued. Among the different possible remediation actions to the debris increase it is the Active Debris Removal (ADR). This paper presents the results of ESA funded COMRADE activity, which pertains to the particular ADR technologies that involves a chaser equipped with robot(s) being operated in tight coordination with the chaser platform motion. Historically, decoupled control and collaborative control have shown that solutions based on them seem to work for some simulated cases (e.g. German DEOS mission and ESA e.Deorbit targeting Envisat satellite). However, concerns are raised by the fact that the attribution of control authority to the robot and platform is arbitrary, tailored to the specific situation and may not be adequate if the actual situation in the ADR mission differs from that modelled ahead of the mission. In addition, the rigid attribution of control authority limits the possibility to treat failures and anomalies with a coordinated approach that may use the highly redundant motion ability of the chaser (possibly higher than 12 Degrees Of Freedom, DOF) to continue the operation unaffected by the contingency.