Determining Grasp Points Using Photometric Stereo and the PRISM Binocular Stereo System

Abstract

This paper describes a system which locates and grasps doughnut shaped parts from a pile. The system uses photometric stereo and binocular stereo as vision input tools. Photometric stereo is used to make surface orientation measurements. With this information the camera field is segmented into isolated regions of continuous smooth surface. One of these regions is then selected as the target region. The attitude of the physical object associated with the target region is determined by histograming surface orientations over that region and comparing with stored histograms obtained from prototypical objects. Range information, not available from photometric stereo is obtained by the PRISM binocular stereo system. A collision-free grasp configuration and approach trajectory is computed and executed using the attitude, and range data.