A Multi-Segmented Soft Finger Using Snap-Through Instability of a Soft Valve With a Slit

Soft fingers with multiple segments can perform various grasping modes when each segment is individually controlled, although this requires a number of inputs and leads to a complicated structure. In this paper, we propose a multi-segment soft finger capable of generating dual modes only using a single input channel. We use the snap-through behavior of a soft spherical shell with a slit as a flow valve between two finger segments. Experimental results showed that geometrical designs and material properties of the valve determine its critical pressure (i.e., the pressure causing buckling of the shell) and affect the proposed soft fingers’ shape deformation and mode transition. We finally characterized an antipodal gripper with two proposed fingers in terms of the acquisition region and grasp robustness. The gripper could achieve not only a broad range of precision grasp by fingers with a passive distal segment but also robust stability of power grasp by fingers with an active distal segment, without adding extra input channels.