Stability analysis of grasped object by soft-fingers based on moment stability

This paper analyze stability of an object grasped by a pair of soft-fingers in two-dimensional space based on moment stability. We firstly define the moment stability as a criterion for stability of a grasped object when the object is perturbed for the orientation. Based on the moment stability, the stability condition of an object grasped by a pair of hard-fingers is derived. We indicate that contact points to satisfy the condition are restricted to upper locations of the center of mass. Next, the condition of an object grasped by a pair of semispherical soft-fingers thirdly is considered. We derive a sufficient condition for the moment stability and indicate that the contact points to satisfy the condition can be in both upper and lower locations of the center of mass. Numerical examples finally are shown. An example shows the grasp situation not to satisfy the condition is established by a slender object with far lower contact locations and its grasp is stable for the faults.