Homogeneous Quantitative Measure of Caging Grasps with both Geometrical and Mechanical Constraints

This paper presents a homogeneous evaluation of difficulty of moving attributed to both geometrical and mechanical constraints. Although caging grasp usually considers to confine an object geometrically by surrounding robots, it is not always feasible due to limitation of robots such as few number of robots or fingers. Such incomplete caging is often called as partial caging, and in which the object can escape from the cage of robots. And then the object is prevented from moving by both geometrical constraints and mechanical effects. The former can be discussed with arrangements of robots and environments, and the latter is investigated with static/dynamic analyses of contact forces. This paper addresses both different indexes homogeneously based on robustness measure for grasping and contact tasks. We introduce a novel interpretation for evaluation of complete/partial caging quality, and show some numerical examples.