Space robots plan moves that handle broken thrusters better
Resilient Motion Planning for Free-Flying Space Robots under Actuator Failures
Robotics
Summary
Space robots use small thrusters to move around in zero gravity, but sometimes these thrusters can break. The authors created a way for the robot to plan its movements while thinking about the chances some thrusters might fail. Their method helps the robot still reach its destination safely by using backup plans and the fact that it will keep moving straight even if it can’t steer. They tested this method on a real robot and showed it can handle thruster failures better.
What this means in practice
- •For spacecraft operators: Create robot maneuvers that maintain control even if some thrusters fail during space missions.
- •For aerospace robotics engineers: Develop navigation software for free-flying robots that maximizes mission success by planning for possible actuator failures.
Authors
Nicolas de Maddalena, Joris Verhagen, Jana Tumova
Abstract
Free-flying robots rely on multiple thrusters to maneuver in space. If one or more of these thrusters fail, the robot may lose control authority and risk mission failure. At the same time, their free-flying nature implies that, even in the absence of actuation, they continue along (locally) straight-line trajectories. In this work we present a probabilistic, proactive, motion planning framework that explicitly accounts for actuator failures in space. We model actuator failure modes as a Markov chain and propagate the probability of successfully reaching the goal along the planning horizon. Precomputed reachable sets evaluate the robot's capabilities of reaching waypoints under potential failures and an RRT$^*$-based planner concatenates these waypoints. The resulting algorithm maximizes the overall target-reaching probability, providing maximally resilient motion plans utilizing free-flying properties. We validate our approach experimentally on a physical free-flyer platform with injected actuator failures.