Kim Woongbae, Byun Junghwan, Kim Jae-Kyeong, Choi Woo-Young, Jakobsen Kirsten, Jakobsen Joachim, Lee Dae-Young, Cho Kyu-Jin
Soft Robotics Research Center, Seoul National University, Seoul, Republic of Korea.
Department of Mechanical and Aerospace Engineering, Institute of Advanced Machines and Design, Seoul National University, Seoul, Republic of Korea.
Sci Robot. 2019 Nov 27;4(36). doi: 10.1126/scirobotics.aay3493.
Nature demonstrates adaptive and extreme shape morphing via unique patterns of movement. Many of them have been explained by monolithic shape-changing mechanisms, such as chemical swelling, skin stretching, origami/kirigami morphing, or geometric eversion, that were successfully mimicked in artificial analogs. However, there still remains an unexplored regime of natural morphing that cannot be reproduced in artificial systems by a "single-mode" morphing mechanism. One example is the "dual-mode" morphing of (commonly known as the pelican eel), which first unfolds and then inflates its mouth to maximize the probability of engulfing the prey. Here, we introduce pelican eel-inspired dual-morphing architectures that embody quasi-sequential behaviors of origami unfolding and skin stretching in response to fluid pressure. In the proposed system, fluid paths were enclosed and guided by a set of entirely stretchable origami units that imitate the morphing principle of the pelican eel's stretchable and foldable frames. This geometric and elastomeric design of fluid networks, in which fluid pressure acts in the direction that the whole body deploys first, resulted in a quasi-sequential dual-morphing response. To verify the effectiveness of our design rule, we built an artificial creature mimicking a pelican eel and reproduced biomimetic dual-morphing behavior. By compositing the basic dual-morphing unit cells into conventional origami frames, we demonstrated architectures of soft machines that exhibit deployment-combined adaptive gripping, crawling, and large range of underwater motion. This design principle may provide guidance for designing bioinspired, adaptive, and extreme shape-morphing systems.
自然界通过独特的运动模式展现出适应性和极端的形状变形。其中许多现象已通过整体形状改变机制得到解释，例如化学膨胀、皮肤拉伸、折纸/切割折纸变形或几何外翻，这些机制已在人工模拟物中成功模仿。然而，仍然存在一种未被探索的自然变形机制，无法通过“单模式”变形机制在人工系统中重现。一个例子是（俗称鹈鹕鳗）的“双模式”变形，它首先展开然后张大嘴巴，以最大化捕获猎物的概率。在这里，我们引入了受鹈鹕鳗启发的双变形架构，该架构体现了折纸展开和皮肤拉伸对流体压力的准顺序响应。在所提出的系统中，流体路径由一组完全可拉伸的折纸单元包围和引导，这些单元模仿了鹈鹕鳗可拉伸和可折叠框架的变形原理。这种流体网络的几何和弹性设计，其中流体压力沿整个身体首先展开的方向作用，导致了准顺序双变形响应。为了验证我们设计规则的有效性，我们构建了一个模仿鹈鹕鳗的人工生物，并重现了仿生双变形行为。通过将基本的双变形单元组合到传统的折纸框架中，我们展示了软机器的架构，该架构表现出结合展开的自适应抓取、爬行和大范围的水下运动。这一设计原则可能为设计受生物启发的、自适应的和极端形状变形系统提供指导。
