A geometric approach to the four-finger grasping planning of polygonal objects

A judging and the planning method of multi-finger grasping for polygonal objects in form closure are proposed. The grasp is frictionless point contact, the grasped object is a planar polygon parts, the number of finger of dexterous robot hand is four, and assume that every finger is appointed to contact one edge of polygon. The concepts of the Instantaneous Rotational Center (IRC) Triangular are illustrated at the first. The representational and the judgmental methods for fourfinger grasping in form closure are studied based on the definitions of IRC triangular, and the identification method of existence for given four edges of the polygonal objects with feasible grasped position by four fingers in form closure is established. The geometric position and position relationships among fingers on grasped polygon in form closure can be expressed by geometric equation. The proposed planning method for form closure grasping by using the IRC triangle is not only geometric distinct but also complete and general. The method also can be extended future so that it is capable of dealing with the object whose profile includes circular edges.