On computation of grasp internal forces for stably grasping multiple objects

When multiple objects are grasped by a multifingered hand, the feasible grasp finger forces are limited directionally because of the geometrical and frictional conditions on the contact parts among the objects. This paper proposes an approach for judging if a group of given fingertip positions is feasible and obtaining the graspable finger force region. In this paper, the generable contact force set for a contact part is discussed from the geometrical and frictional conditions of the part. Based on the contact force sets for all contact parts, an algorithm to obtain the set of the internal finger forces which can be generated actually is analyzed. Then an algorithm to obtain the set of the internal finger forces which can hold all objects fast and stably is addressed. Lastly, numerical examples and their experiments are performed to verify the effectiveness of the proposed approach.