Fabric based flexible gripper

We study the mechanics of curved elastic tubes consisting of two thin, flat, quasi-inextensible sheets sealed together, which react in such a way that their reference curvature is amplified when inflated. We focus on V-shaped tubes with sharp corners that deform so that the initial angle between the arms decreases upon inflation, acting as a hinge-like mechanism. We first characterize the kinematic and mechanical response of an individual hinge through a combination of experiments and finite element modeling. We build a soft gripper that consists of a star-shaped tube consisting of successive V-shaped tubes forming a closed loop. Upon inflation, the structure contracts radially and provides a flexible gripping solution with adjustable gripping force. Based on the mechanical description of individual hinges, we address the inverse problem and optimize the closed loop geometry and operational conditions to achieve a target gripping force for the gripper.