混合刚度仿人指尖扩大硬币抓取的工作范围

发表机构

The University of Electro-Communications（电气通信大学）

AI 中文总结

本研究提出混合刚度仿人指尖设计，实验显示其在硬币抓取的多数测试条件下成功率优于均匀软指尖，为薄物体抓取的工作范围扩展提供了新的指尖设计变量。

AI 中文摘要

机器人抓取坚硬表面上的薄而扁平物体（如硬币）仍具挑战性，因为传统方法需要重新定向物体、接触其下侧或添加专用指甲机构。我们此前表明，刚性指甲可阻止软指垫变形，从而形成几何约束，提升精准抓取性能。本研究探究是否可通过材料选择而非解剖结构在指垫内形成额外的约束边界，以扩展该约束的适用条件。我们制备了中心为Shore E10硅橡胶、两侧为Shore A60硅橡胶的仿人指尖（混合刚度指尖），并与均匀软E10指尖进行对比。自动化装置执行倾斜旋转指尖捏取动作，指垫接触硬币侧面，将其从无间隙的贴合接触状态抬起。在水平接近距离、垂直手指位移及食指旋转的多种变化条件下，混合刚度指尖对在几何约束形成及稳定抓取过渡阶段，于更多测试设置中维持高成功率，而无指甲的指尖在实验1-1的全部36种条件下均失败。不过，当硬币沿手指轴位置变化时，均匀软指尖表现更好，存在条件依赖的权衡。经针对硬币尺寸调整后，两种指尖均可抓取全部六种日本面额硬币。这些结果表明，薄物体抓取的工作范围不仅取决于指垫软度，还取决于指甲支撑的指垫内刚度的位置，使边界位置成为指尖设计的可选变量。

英文摘要

Robotic grasping of thin, flat objects such as coins on hard surfaces remains challenging because conventional methods require reorienting the object, accessing its underside, or adding a dedicated nail mechanism. We previously showed that a rigid nail arrests soft-pad deformation and thereby forms a geometric constraint that improves precision grasping. Here we asked whether an additional constraint-forming boundary, created within the pad by material choice rather than by anatomy, could extend the conditions under which that constraint holds. We fabricated anthropomimetic fingertips with Shore E10 silicone at the center and Shore A60 at the sides, and compared them with uniformly soft E10 fingertips. An automated apparatus performed an oblique rotational tip pinch in which the pad engaged the coin's lateral surface, lifting it from flush contact with no gap beneath it. Over variations in horizontal approach distances, vertical finger displacements, and index-finger rotation, the mixed-stiffness pair maintained high success rates across more tested settings than the uniform pair during both geometric-constraint formation and the transition to a stable grasp. The nail-free pair failed in all 36 conditions of Experiment 1-1. However, the uniform pair performed better when coin position along the finger axis was varied, a condition-dependent trade-off. After tuning for coin size, both fingertip types grasped all six Japanese denominations. These results suggest that the operating range for thin-object grasping depends not only on pad softness but also on where stiffness is placed within a nail-supported pad, making boundary placement a candidate fingertip design variable.

论文原文

arXiv 摘要页 · PDF 原文 · HTML 原文

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