Adaptive-twist Soft Finger Mechanism for Grasping by Wrapping

TL;DR

This paper introduces an adaptive-twist soft finger mechanism enabling wrapping grasping through variable stiffness control, demonstrated via FEA and experiments on grasping diverse objects.

Contribution

It proposes a novel soft finger with adaptive-twist deformation and variable stiffness control for improved grasping capabilities.

Findings

Successful grasping of various objects demonstrated

Finite element analysis validated the design parameters

The mechanism enables deep insertion among objects

Abstract

This paper presents a soft robot finger capable of adaptive-twist deformation to grasp objects by wrapping them. For a soft hand to grasp and pick-up one object from densely contained multiple objects, a soft finger requires the adaptive-twist deformation function in both in-plane and out-of-plane directions. The function allows the finger to be inserted deeply into a limited gap among objects. Once inserted, the soft finger requires appropriate control of grasping force normal to contact surface, thereby maintaining the twisted deformation. In this paper, we refer to this type of grasping as grasping by wrapping. To achieve these two functions by a single actuation source, we propose a variable stiffness mechanism that can adaptively change the stiffness as the pressure is higher. We conduct a finite element analysis (FEA) on the proposed mechanism and determine its design parameter based on the FEA result. Using the developed soft finger, we report basic experimental results and demonstrations on grasping various objects.