Inspired by the snap-through action of a steel hairclip, we propose a design method for in-plane prestressed mechanisms that exhibit biomimetic morphing and high locomotion performance. Compliant bistable flapping mechanisms are fabricated using this method and are mounted on our untethered soft robotic fish. Using this mechanism, we achieve life-like undulation with a Strouhal number (1) of St = 0.28 and a velocity of 2.03 body lengths per second (43.6 cm/s), a three-fold improvement over past compliant fish robots. A tethered pneumatic version indicates that this mechanism is compatible with soft actuators. We study the mechanism both computationally and experimentally and suggest that elastic instability may offer a path to overcome the speed challenge of soft and compliant robots.

翻译：受钢制发夹快速弹跳动作的启发，我们提出了一种面向平面内预应力机构的设计方法，该机构能够实现仿生变形并具备高运动性能。采用该方法制造了双稳态柔性扑翼机构，并将其安装于我们的无系绳软体机器鱼上。利用该机构，我们实现了仿生波动运动，斯特劳哈尔数St=0.28，速度达2.03体长/秒（43.6厘米/秒），较此前柔性机器鱼的三倍提升。一种系绳气动版本表明该机构可与软体致动器兼容。我们通过计算与实验相结合的方式对该机构进行了研究，结果表明弹性失稳可能为克服软体及柔性机器人速度瓶颈提供一条有效路径。