Collective dynamics in entangled worm and robot blobs
Collective dynamics in entangled worm and robot blobs
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DOI：
10.1073/pnas.2010542118
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发表时间：
2021-02-09
影响因子：
11.1
通讯作者：
Bhamla, M. Saad
中科院分区：
文献类型：
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作者：
Ozkan-Aydin, Yasemin;Goldman, Daniel, I;Bhamla, M. Saad
各种规模的生命系统为了各种功能而大量聚集，包括交配、捕食和生存。大多数此类系统由不相连的个体组成，这些个体集体聚集、聚集或集群。然而，一些聚合涉及物理纠缠的个体，这可以赋予集体新兴的机械功能材料特性。在这里，我们在实验室实验中研究并在理论和机器人物理模型中合理化 1 厘米长的加州黑虫（Lumbriculus variegatus，环节动物：Clitellata：Lumbriculidae）的物理纠缠和运动自组装的动力学。数以千计的蠕虫个体用它们细长且灵活的身体形成辫子，形成三维、柔软且可变形的“团块”。该斑点作为一种生命材料，能够通过动态形状转变来减轻环境压力造成的损害和攻击，包括最小化表面积以防止干燥并实现危险环境（如高温）的运输（负趋热性）。我们特别关注斑点的运动，以了解无定形纠缠蠕虫球如何打破对称性以在基板上移动。我们假设集体斑点显示出其自身功能的基本分化，当与纠缠动力学相结合时，有利于斑点的定向持续运动。为了测试这一点，我们开发了蠕虫斑点的机器人物理模型，该模型显示集体中的紧急运动，而无需对任何单个机器人进行复杂的控制或编程。生命功能斑点和机器人物理模型的新兴动力学可以为其他类别的自适应机械功能生命材料和新兴机器人的设计提供信息。
Living systems at all scales aggregate in large numbers for a variety of functions including mating, predation, and survival. The majority of such systems consist of unconnected individuals that collectively flock, school, or swarm. However, some aggregations involve physically entangled individuals, which can confer emergent mechanofunctional material properties to the collective. Here, we study in laboratory experiments and rationalize in theoretical and robophysical models the dynamics of physically entangled and motile self-assemblies of 1-cm-long California blackworms (Lumbriculus variegatus, Annelida: Clitellata: Lumbriculidae). Thousands of individual worms form braids with their long, slender, and flexible bodies to make a three-dimensional, soft, and shape-shifting "blob." The blob behaves as a living material capable of mitigating damage and assault from environmental stresses through dynamic shape transformations, including minimizing surface area for survival against desiccation and enabling transport (negative thermotaxis) from hazardous environments (like heat). We specifically focus on the locomotion of the blob to understand how an amorphous entangled ball of worms can break symmetry to move across a substrate. We hypothesize that the collective blob displays rudimentary differentiation of function across itself, which when combined with entanglement dynamics facilitates directed persistent blob locomotion. To test this, we develop a robophysical model of the worm blobs, which displays emergent locomotion in the collective without sophisticated control or programming of any individual robot. The emergent dynamics of the living functional blob and robophysical model can inform the design of additional classes of adaptive mechanofunctional living materials and emergent robotics.