Soft grasping is a great challenge for picking robots and its bionic inspiration originates from human fingers. In this study, the hand was scanned to obtain the internal structure of fingers by a computerized tomography (CT) scanner, and the soft contact mechanical index a was defined for characterizing the degree of softness of a finger region during gentle grasping. The effects of mechanics and structure of finger tissues on the soft contact mechanical index were investigated by finite element analysis and multiple linear regression. The finite element models of the 14 finger regions were split into 6 different groups by a hierarchical cluster analysis. In each group, a mathematical model was established to link the soft contact mechanical index with the mechanics as well as the structure of finger tissues. In most finger regions, their soft contact mechanical index significantly depended on the elastic moduli of the skin and subcutaneous tissue (E_skin, E_tissue), the Poisson’s ratio ʋ_tissue and the thickness T_tissue of the subcutaneous tissue (p < 0.05). The E_tissue showed the most contribution on the soft contact mechanical index of a finger region, followed by ʋ_tissue, T_tissue, and E_skin. This study demonstrated how the mechanics and structure of the human finger quantitatively affect its soft contact mechanical behavior during gentle grasping and further provided a bionic basis for developing robotic fingers with varying degrees of softness, particularly for fruit picking.

对于抓取机器人而言，软抓握是一项巨大的挑战，其仿生灵感源于人的手指。在这项研究中，通过计算机断层扫描（CT）扫描仪对手进行扫描以获得手指的内部结构，并且软接触机械指数为a。被定义用于表征在轻抓的过程中手指区域的柔软度。通过有限元分析和多元线性回归研究了手指组织的力学和结构对软接触力学指标的影响。通过层次聚类分析，将14个手指区域的有限元模型分为6个不同的组。在每组中，建立了数学模型以将软接触机械指数与手指组织的力学和结构联系起来。在大多数指区，它们的软接触机械指数显著依赖于皮肤和皮下组织（的弹性模量ë_皮肤，ë_组织），泊松比ʋ_组织皮下组织的厚度T_组织（p  <0.05）。该ê_组织表现出对手指区域的软接触机械指数的贡献最大，其次是ʋ_组织，牛逼_组织和ē_皮肤。这项研究证明了人手指的机械结构如何在轻柔地抓握过程中定量地影响其软接触机械行为，并进一步为开发具有不同柔软度的机器人手指（尤其是摘水果）提供了仿生基础。