CRII: RI: Robotic cable-based de-tumbling of demised spacecraft

Technologies based on satellites are nowadays ubiquitous and essential to our everyday life. However, they are continuously threatened by the possibility of collisions between operational satellites and space debris, formed of all non-functional objects in orbit around the Earth. Robotic missions to dispose of large debris are currently being proposed to reduce the risk of such collisions.

The objective of this research is to develop knowledge to put in practice autonomous cable-based de-tumbling of uncooperative space objects. Tether-net systems will be considered, which are thrown toward debris, entangle it or close around it, and provide a link to tug it to a disposal orbit. Focus of this research will be the modeling, analysis, and control of the chaser-net-target spacecraft system after capture, when the relative motion of the two satellites is particularly dangerous.

Cable-based robots provide innovative solutions not only to applications such as debris capture and on-orbit servicing, but also asteroid deflection and drone interception. The advancements brought about by this research have the potential to positively impact national defense, increase the economic competitiveness of spacecraft solutions, and advance national prosperity.

Activities to broaden participation in STEM will include research experiences for undergraduates, integration of research results in the curriculum, and outreach in underprivileged elementary schools.

The objective of this research will be attained by (1) high-fidelity modeling and analysis of the interactions between the cable-based robot and the target, and (2) control of the cable-based robot. In one thrust of the proposed work, high fidelity models will be developed to represent the dynamics of the cable-based robot as well as frictional interactions with the target.

Reduced order but dynamically equivalent models will be created to provide an efficient but accurate alternative. A methodology to estimate the inertial parameters of the unknown, uncooperative target will also be proposed. The other research component aims to leverage the limited control authority of the cable-based robot to synthesize reliable and robust control methods.

Options related to the winching of the main tether as well as to the thrusters of the chaser will be considered. Feedback control will be employed to stabilize at the same time the relative translational and attitude dynamics of the chaser and the target spacecraft. The robustness of the control to uncertainties will also be verified.

These contributions are expected to enable important technological advancements of autonomous cable-based systems for space applications, while advancing the knowledge of nonlinear systems dynamics, model-based estimation, and control of complex nonlinear systems with limited authority.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.