Soft capture of rotating debris with free-floating space robot

Capturing rotating space debris using free-floating robotic systems entails complex challenges in motion planning and control. This paper proposes a soft-capture trajectory planning framework designed for the safe and efficient capture of rotating targets. The capture maneuver is decomposed into two sequential phases: an approach phase and a tracking phase. In the approach phase, a velocity-level planner simultaneously determines the initial berthing position of the base spacecraft and the minimum maneuver time required to reach a target-centered safety zone, obviating the need for predefined paths in Cartesian or joint space. The subsequent tracking phase employs jerk-level optimization to generate smooth joint-space trajectories, ensuring end-effector alignment and achieving zero relative position and velocity at contact, while simultaneously minimizing base attitude disturbances. Formulated as quadratic programs, both phases exploit the manipulator’s kinematic redundancy and leverage the system’s initial momentum, enabling time-efficient solutions suitable for online implementation while satisfying collision avoidance and joint-limit constraints. Numerical simulations using a 7-degree-of-freedom manipulator demonstrate the effectiveness of the proposed method, yielding minimum-time approach performance and high-precision tracking with sub-millimeter positional accuracy. Furthermore, the trajectories exhibit smooth, bounded accelerations and jerks, with base attitude disturbance restricted to less than 1.5^∘. These results validate the framework’s suitability for active debris removal and in-space servicing applications.