In context
In early 2023, on-orbit servicing and space debris removal were gaining momentum, with robotic systems increasingly tasked to capture non-cooperative targets such as defunct satellites. A key challenge after capture is stabilizing the tumbling target, which requires careful planning and control under input constraints. This paper from Northwestern Polytechnical University addressed that problem with a novel detumbling strategy.
What was reported
The authors proposed a detumbling planning and control method for a dual-arm space robot after capturing a spinning target, explicitly considering the robot's input constraints. The method builds on a dynamic model of the combined system and introduces a fast detumbling strategy based on dynamic manipulability and task compatibility. The desired target acceleration is set opposite to its velocity, with magnitude maximized within the allowable input limits.
To handle uncertainties in target inertia parameters and reduce internal forces, a compliant control method was developed. It establishes compliance equations for both the target and the end-effectors, enabling trajectory tracking while regulating contact forces. The approach avoids complex optimization algorithms, using geometric insights from manipulability ellipsoids.
Simulations with a 7-degree-of-freedom dual-arm space robot demonstrated the effectiveness of the method in eliminating target rotational motion, confirming its practical viability.
Why it mattered
This work advanced the field of autonomous space robotics by providing a computationally efficient detumbling solution that respects real-world actuator limits. It offered a practical framework for stabilizing captured targets, which is critical for future missions involving satellite servicing, active debris removal, and in-orbit assembly.
"The desired acceleration of the target is taken as the opposite direction of its velocity, and its magnitude is determined according to the dynamic manipulability and task compatibility of the current manipulator configuration, thereby achieving the fastest detumbling within the force and torque input limits of the robotic system."
Source: 《机器人》期刊 (robot.sia.cn) · Published 2023-03-06 · “空间机器人抓捕目标后基于任务相容性的消旋策略”