Papers

Multi-Link Safety Filtering for VLA Policies Around Moving Hazards

This preprint introduces a training-free runtime safety filter that wraps a pretrained vision-language-action policy, shielding the gripper, wrist, and forearm with five ellipsoids and tracking moving hazards via sparse optical flow. Across six simulated hazard-motion conditions it cuts the collision rate from 65.62% to 27.27% and lifts safe task completion from 29.35% to 50.43%, while a small 16-episode physical arm test shows 3/16 shielded contacts versus 11/16 unshielded. The barrier runs in about 2 ms on CPU, showing onboard shielding is feasible without retraining.