Grasp synthesis and fingertips motion planning for robotics dextrous hands

This paper concerns object manipulation with robotic dexterous hands using the fingertips. Two important aspects in the manipulation scheme are developed; the first one concerns grasp synthesis; it means that the choice of the initial grasp is done before the manipulation begins; and the second one concerns fingertips motion planning. Thus the LMS Hand of the ROBIOSS team from PPRIME Institute of Poitiers (France) is used as a demonstrator. The proposed strategy is first based on the use of an expert system for solving the grasp synthesis problem. As we wish to manipulate with the fingertips, we do not consider power grasp involving whole parts of fingers; so we propose to synthesize precision grasp. Human grasp analysis is used to teach the expert system. Thus the experimental protocol using motion capture is detailed and results are discussed. To complete this strategy a geometrical approach for motion planning based on a contact modeling between the grasped object and the fingertip is given. It offers a robust solution for solving the fingertips motion aiming for object manipulation. In order to validate the whole strategy, different manipulation tasks are presented and detailed with a three-dimensional CAD software dedicated to robotic simulation : SMAR developed by the PPRIME Institute.