Bujard Thierry, Giorgio-Serchi Francesco, Weymouth Gabriel D
Engineering and Physical Sciences, University of Southampton, Southampton, UK.
School of Engineering, University of Edinburgh, Edinburgh, UK.
Sci Robot. 2021 Jan 20;6(50). doi: 10.1126/scirobotics.abd2971.
Elasticity has been linked to the remarkable propulsive efficiency of pulse-jet animals such as the squid and jellyfish, but reports that quantify the underlying dynamics or demonstrate its application in robotic systems are rare. This work identifies the pulse-jet propulsion mode used by these animals as a coupled mass-spring-mass oscillator, enabling the design of a flexible self-propelled robot. We use this system to experimentally demonstrate that resonance greatly benefits pulse-jet swimming speed and efficiency, and the robot's optimal cost of transport is found to match that of the most efficient biological swimmers in nature, such as the jellyfish The robot also exhibits a preferred Strouhal number for efficient swimming, thereby bridging the gap between pulse-jet propulsion and established findings in efficient fish swimming. Extensions of the current robotic framework to larger amplitude oscillations could combine resonance effects with optimal vortex formation to further increase propulsive performance and potentially outperform biological swimmers altogether.
弹性与诸如鱿鱼和水母等脉冲喷射动物卓越的推进效率相关联，但量化其潜在动力学或证明其在机器人系统中应用的报告却很少见。这项工作将这些动物使用的脉冲喷射推进模式识别为一种耦合质量 - 弹簧 - 质量振荡器，从而实现了一种柔性自推进机器人的设计。我们利用该系统通过实验证明，共振极大地有利于脉冲喷射游泳速度和效率，并且发现机器人的最佳运输成本与自然界中最有效的生物游泳者（如水母）相匹配。该机器人在高效游泳时还表现出一个优选的斯特劳哈尔数，从而弥合了脉冲喷射推进与高效鱼类游泳方面既定研究结果之间的差距。将当前机器人框架扩展到更大振幅的振荡，可以将共振效应与最佳涡旋形成相结合，以进一步提高推进性能，并有可能在总体上超越生物游泳者。
