Dynamic Sphere Envelopes and SFF-DMP for Real-Time Obstacle Avoidance in Space Cable Assembly

This letter addresses real-time obstacle avoidance and precision manipulation in on-orbit cable disassembly tasks involving flexible, vibrating cables. We propose a control framework that combines dynamic sphere envelopes with a Steering Force Field enhanced Dynamic Movement Primitive (SFF-DMP) formulation. The dynamic sphere envelopes approximate oscillating cables with radius adaptive virtual obstacles, enabling compact geometric representations of flexible dynamics. The proposed SFF-DMP integrates a Cartesian-space DMP with a steering force field, enabling smooth and reliable obstacle avoidance with low free-space loss, while the joint-space DMP preserves demonstration similarity and tracking accuracy through null-space optimization. Cable dynamics modeling and simulation studies validate the method's capability to avoid time-varying obstacles, and experiments on electrical connector disassembly demonstrate that a single cable free demonstration can generalize to multiple disturbed configurations. Results show consistent collision-free execution with position error below 0.7 mm and orientation error below 0.011 rd. The proposed approach offers a low-demonstration-cost, high-space-efficiency solution for safe manipulation in dynamic and constrained space environments.