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:在不同物种和不同尺度上,一些生物利用他们的附肢通过缠绕而非夹紧来抓取物体。这种运动模式在章鱼触手、大象象鼻和变色龙的抓揪尾等生物身上都发现了,展现了在三维空间中抓取各种大小和重量的物体以及动态操纵它们的极大灵活性。我们观察到这些附肢的结构遵循一种共同的图案-对数螺旋形-这对于现有机器人设计来说非常具有挑战性。本文报道了一类电缆驱动软性机器人的设计、制造和操作,这些机器人形态上复制了螺旋形包装。这相当于在积极控制卷曲方向的情况下,长度大大卷曲。两个原则使其成为可能:基于对数螺旋的参数化设计使其能够通过紧密包裹抓取大小相差两个数量级甚至达到260倍自重的物体;非对称电缆力量允许快速控制卷曲方向进行物体操纵。我们通过利用被动柔顺度,展示了在亚秒级别对物体进行动态操作的能力。我们认为我们的研究是朝着包裹抓取和操纵的工程系统迈出的一步,进一步为了解生物螺旋形附肢的有效性提供了一些见解。