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 Aurelia aurita. 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.

弹性与鱿鱼和水母等脉冲喷射动物的卓越推进效率有关，但量化潜在动力学或证明其在机器人系统中应用的报告很少见。这项工作将这些动物使用的脉冲喷射推进模式确定为耦合质量-弹簧-质量振荡器，从而能够设计出灵活的自行式机器人。我们使用该系统通过实验证明共振极大地有益于脉冲喷射游泳的速度和效率，并且发现机器人的最佳运输成本与自然界中最高效的生物游泳者（例如水母Aurelia aurita）相匹配. 该机器人还表现出用于高效游泳的首选 Strouhal 数，从而弥合了脉冲喷射推进与高效鱼类游泳的既定发现之间的差距。将当前的机器人框架扩展到更大幅度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可能完全超越生物游泳者。