Across various species and different scales, certain organisms use their appendages to grasp objects not through clamping but through wrapping. This pattern of movement is found in octopus tentacles, elephant trunks, and chameleon prehensile tails, demonstrating a great versatility to grasp a wide range of objects of various sizes and weights as well as dynamically manipulate them in the 3D space. We observed that the structures of these appendages follow a common pattern - a logarithmic spiral - which is especially challenging for existing robot designs to reproduce. This paper reports the design, fabrication, and operation of a class of cable-driven soft robots that morphologically replicate spiral-shaped wrapping. This amounts to substantially curling in length while actively controlling the curling direction as enabled by two principles: a) the parametric design based on the logarithmic spiral makes it possible to tightly pack to grasp objects that vary in size by more than two orders of magnitude and up to 260 times self-weight and b) asymmetric cable forces allow the swift control of the curling direction for conducting object manipulation. We demonstrate the ability to dynamically operate objects at a sub-second level by exploiting passive compliance. We believe that our study constitutes a step towards engineered systems that wrap to grasp and manipulate, and further sheds some insights into understanding the efficacy of biological spiral-shaped appendages.

翻译：在不同物种及尺度下，某些生物并非通过夹持而是通过缠绕来抓取物体。这种运动模式存在于章鱼触手、大象鼻子和变色龙的卷尾中，展现出抓取各种尺寸与重量物体以及在三围空间中动态操控物体的高度通用性。我们观察到这些附肢的结构遵循一种共同模式——对数螺旋线——这一特征对现有机器人设计而言极具复制挑战。本文报告了一类线驱动软体机器人的设计、制造与运行机制，其在形态上复现了螺旋状缠绕。这实现了大幅度的弯曲收缩，同时可主动控制弯曲方向，主要基于两个原理：a) 基于对数螺线的参数化设计使其能够紧密包裹抓取尺寸差异超过两个数量级、自重达260倍的物体；b) 非对称线张力可快速控制弯曲方向以进行物体操控。我们展示了利用被动柔顺性在亚秒级时间内动态操控物体的能力。我们相信本研究标志着向通过缠绕实现抓取与操控的工程系统迈进一步，并为理解生物螺旋附肢的功效提供了新见解。