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.

翻译：本文提出了一种能够通过自适应扭转变形实现包裹抓取物体的软体机器人手指。为使软体手能够在密集堆叠的多个物体中抓取并提起单个物体，软体手指需具备面内与面外方向的自适应扭转变形功能。该功能使手指能够深入物体间的狭窄间隙。插入后，软体手指需对接触面法向的抓取力进行精确控制，从而维持扭转变形状态。本文将此类抓取方式称为包裹式抓取。为实现单一驱动源同时完成这两项功能，我们提出一种可变刚度机构，其刚度可随压力增大而自适应调整。通过对该机构进行有限元分析（FEA），我们依据分析结果确定了设计参数。基于所开发的软体手指，我们报告了抓取多种物体的基础实验结果与演示案例。