In this paper, grasping strategy using deformation of soft finger is addressed. Soft fingers, which are made of macromolecular and have large elastic deformation, have gotten a lot of attention. Soft fingers have a peculiarity that high friction force, which stabilizes a grasping condition, is generated by expansion of contact area between tip of soft finger and grasping object. However, until now nobody focuses on the fact that deformation of soft finger enables multi-fingered hand to generate force to manipulate a object which has high aspect ratio and restricted by environment. Accordingly, we focus on a task to pick up a thin plate on a floor using deformation of soft finger. The effectiveness of grasping strategy is confirmed by experiments.

This paper discusses practical strategies for transition from a pinching to a power grasping, where a multi-fingered hand mounted on a robotic arm envelops a cylindrical object on a table. When the manipulation system grasps a cylindrical object like a pen on a desk, a complete enveloping is not impossible in the initial configuration. The system firstly pinches the object only with two or three fingers and then grasps it with fingers and a palm after regrasping. In this pinching-grasping transition maneuver, human unconsciously selects proper strategy according to some conditions including object dimensions and initial pinching positions. In this paper we therefore develop six possible strategies for this pinching-grasping transition and then investigate their performances for some objects with various dimensions and various grasping positions, using numerical simulations. Based on their results, a strategy selection algorithm for these conditions is proposed and some experiment results are shown.