Pose from Pushing

Abstract

In the absence of vision, grasping an object often relies on tactile feedback from the fingertips. Before force closure is formed, where on the object a fingertip touches can usually be felt from the motion of contact on the fingertip during a small amount of pushing. In this paper we investigate the first stage of such ``blind'' grasping. More specifically, we study the problem of determining the pose of a known planar object by pushing. Assuming sliding friction in the plane, a dynamic analysis of pushing results in a numerical algorithm that computes the object pose from three instantaneous contact positions on a fingertip. Simulations and experiments (with an Adept robot) have been conducted to demonstrate the sensing feasibility. Inspired by the way a human hand grasps, this work can be viewed as a primitive step in exploring interactive sensing in grasping tasks.