CAD-based grasp synthesis utilizing polygons, edges and vertexes

A CAD-based grasp-synthesis system has been developed that precomputes valid, stable grasp sites on CAD models for use by a robot system. Extended Gaussian images, which are efficient data structures for mapping surfaces into Gaussian space based on surface normals, are shown. A modified version is introduced which allows the mapping of polygon, edge, and vertex normals. Using the modified extended Gaussian image, pairs of parallel surfaces are found in linear time. Pairs of graspable surfaces include polygon-polygon, polygon-edge, and polygon-point. A method of computing the rotational stability of edge contacts is given. The stability of each grasp point and its orientation are computed, and all grasps are ranked in descending order of stability. The grasp-synthesis program is demonstrated on three models, one concave and two convex; all three types of grasps are shown