Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba Ward, Sendai, Miyagi 980-8577, Japan.
Integr Comp Biol. 2020 Jul 1;60(1):232-247. doi: 10.1093/icb/icaa014.
Snakes have no limbs and can move in various environments using a simple elongated limbless body structure obtained through a long-term evolutionary process. Specifically, snakes have various locomotion patterns, which they change in response to conditions encountered. For example, on an unstructured terrain, snakes actively utilize the terrain's irregularities and move effectively by actively pushing their bodies against the "scaffolds" that they encounter. In a narrow aisle, snakes exhibit concertina locomotion, in which the tail part of the body is pulled forward with the head part anchored, and this is followed by the extension of the head part with the tail part anchored. Furthermore, snakes often exhibit three-dimensional (3-D) locomotion patterns wherein the points of ground contact change in a spatiotemporal manner, such as sidewinding and sinus-lifting locomotion. This ability is achieved possibly by a decentralized control mechanism, which is still mostly unknown. In this study, we address this aspect by employing a synthetic approach to understand locomotion mechanisms by developing mathematical models and robots. We propose a Tegotae-based decentralized control mechanism and use a 2-D snake-like robot to demonstrate that it can exhibit scaffold-based and concertina locomotion. Moreover, we extend the proposed mechanism to 3D and use a 3-D snake-like robot to demonstrate that it can exhibit sidewinding and sinus-lifting locomotion. We believe that our findings will form a basis for developing snake-like robots applicable to search-and-rescue operations as well as understanding the essential decentralized control mechanism underlying animal locomotion.
蛇类没有四肢，但通过长期进化获得的简单、无肢的身体结构，能够在各种环境中移动。具体来说，蛇类有各种运动模式，它们会根据遇到的情况进行改变。例如，在无结构的地形上，蛇类积极利用地形的不规则性，通过主动将身体推向遇到的“支撑物”来有效地移动。在狭窄的通道中，蛇类会表现出节段性运动，即身体的尾部部分被向前拉动，头部部分固定，然后头部部分固定，尾部部分延伸。此外，蛇类经常表现出三维（3-D）运动模式，其中地面接触点以时空方式变化，例如蜿蜒运动和正弦波提升运动。这种能力可能是通过分散控制机制实现的，而这种机制在很大程度上仍然未知。在这项研究中，我们通过采用综合方法来理解运动机制，通过开发数学模型和机器人来解决这个问题。我们提出了一种基于 Tegotae 的分散控制机制，并使用 2-D 蛇形机器人来证明它可以表现出基于支撑物和节段性的运动。此外，我们将提出的机制扩展到 3D，并使用 3-D 蛇形机器人来证明它可以表现出蜿蜒运动和正弦波提升运动。我们相信，我们的发现将为开发适用于搜索和救援行动的蛇形机器人以及理解动物运动的基本分散控制机制奠定基础。
