Analysis of Open-Loop Grasping From Piles

Abstract

This paper offers an explanation of why humans can effortlessly grasp objects from a pile. We identified a regularity in objects’ motion when pushed, namely, an object separates and stabilizes in front of the pusher. We devise an open-loop grasping strategy leveraging this regularity in piles of nearly identical objects. Our real robot robustly grasps round objects beside a wall with success rates between 95% and 100% without visual or tactile feedback. We analyze our grasping strategy extensively both in real-world and simulated experiments. We observe that object roundness improves grasping and the motion pattern also manifests in small piles beside a wall. Our qualitative simulation can approximate the real robot’s grasping behavior, and we apply open-loop grasping in an warehouse pick-and-place application.