Lynch James, Wold Ethan S, Gau Jeff, Sponberg Simon, Gravish Nick
Department of Mechanical & Aerospace Engineering, University of California, San Diego, CA, United States of America.
School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States of America.
Bioinspir Biomim. 2024 Dec 23;20(1). doi: 10.1088/1748-3190/ad9535.
Flying insects are thought to achieve energy-efficient flapping flight by storing and releasing elastic energy in their muscles, tendons, and thorax. However, 'spring-wing' flight systems consisting of elastic elements coupled to nonlinear, unsteady aerodynamic forces present possible challenges to generating stable and responsive wing motion. The energetic efficiency from resonance in insect flight is tied to the Weis-Fogh number (), which is the ratio of peak inertial force to aerodynamic force. In this paper, we present experiments and modeling to study how resonance efficiency (which increases with) influences the control responsiveness and perturbation resistance of flapping wingbeats. In our first experiments, we provide a step change in the input forcing amplitude to a series-elastic spring-wing system and observe the response time of the wing amplitude increase. In our second experiments we provide an external fluid flow directed at the flapping wing and study the perturbed steady-state wing motion. We evaluate both experiments across Weis-Fogh numbers from1<N<10. The results indicate that spring-wing systems designed for maximum energetic efficiency also experience trade-offs in agility and stability as the Weis-Fogh number increases. Our results demonstrate that energetic efficiency and wing maneuverability are in conflict in resonant spring-wing systems, suggesting that mechanical resonance presents tradeoffs in insect flight control and stability.
人们认为，飞行昆虫通过在其肌肉、肌腱和胸部储存并释放弹性能量来实现节能的扑翼飞行。然而，由与非线性、非定常气动力耦合的弹性元件组成的“弹簧翼”飞行系统，在产生稳定且响应灵敏的机翼运动方面可能存在挑战。昆虫飞行中共振的能量效率与魏斯 - 福格数（）相关，该数是峰值惯性力与气动力的比值。在本文中，我们通过实验和建模来研究共振效率（随该数增加）如何影响扑翼节拍的控制响应性和抗扰性。在我们的首次实验中，我们对串联弹性弹簧翼系统的输入强迫振幅进行阶跃变化，并观察机翼振幅增加的响应时间。在我们的第二次实验中，我们向扑翼施加外部流体流，并研究受扰的稳态机翼运动。我们在魏斯 - 福格数范围为1<N<10的情况下对这两个实验进行评估。结果表明，随着魏斯 - 福格数的增加，为实现最大能量效率而设计的弹簧翼系统在敏捷性和稳定性方面也会面临权衡。我们的结果表明，在共振弹簧翼系统中，能量效率和机翼机动性存在冲突，这表明机械共振在昆虫飞行控制和稳定性方面存在权衡。
