A Robust Observation, Planning, and Control Pipeline for Autonomous Rendezvous with Tumbling Targets.

Area of Science:

• Robotics and Autonomous Systems
• Spacecraft Engineering
• Orbital Mechanics

Background:

• The increasing amount of space debris and non-functional satellites threatens the sustainable use of space, potentially leading to Kessler syndrome.
• Servicing or deorbiting satellites in high orbits and managing tumbling debris presents significant challenges due to unpredictable motion.
• Current rendezvous missions are advancing, but practical solutions for autonomous docking with uncontrolled tumbling targets are undemonstrated.

Purpose of the Study:

• To propose and demonstrate a complete pipeline for autonomous rendezvous and docking with tumbling space targets.
• To develop and integrate algorithms for target state estimation, motion planning, and robust control under uncertainty.
• To address the critical need for active debris removal and on-orbit servicing capabilities.

Main Methods:

• A novel visual estimation algorithm using a 3D time-of-flight camera for remote estimation of target rotational state and axes.
• A nonlinear programming-based motion planning algorithm utilizing offline simulations and a lookup table for on-orbit execution.
• An uncertainty characterization method and a robust tube model predictive controller for guaranteed trajectory tracking.

Main Results:

• Successful simulation of the complete pipeline, from standoff estimation to mating in the target's rotating frame.
• Demonstration of robust control that accounts for target tumble uncertainty and provides translational tracking guarantees.
• Validation of individual components and the integrated system through comprehensive case studies.

Conclusions:

• The proposed pipeline offers a viable solution for autonomous rendezvous and docking with tumbling space objects.
• The integrated approach addresses key challenges in active debris removal and on-orbit servicing.
• The system is being prepared for demonstration on the International Space Station, following successful Astrobee free-flyer tests.