3-D firm grasps with the SCROLLIC gripper

Firm and stable 3-D grips have been achieved for articulated multifinger hands, easing object handling tasks under uncertainties. In this paper, the authors propose a new concept of two-fingered parallel gripper, which they name SCROLLIC (acronym for synchronously closing with rolling constraints). It provides multiple contacts and enables objects of a general shape to be held. Its design and functioning are exposed in detail, as well as the model of the workspace where firm grasps are achievable. For this workspace, a force-closure grasp is always possible when a form-closure is not realizable. A quality function to evaluate the grasp is modeled and a basic application for the gripper is shown. Although acting basically as a planar parallel-jaw gripper, the new gripper offers great stability and firmness in grasping.