RAISE: Spring & Wings: Resonance in insect and engineered flight with synchronous and stretch-activated actuation

该跨学科科学与工程研究（RAISE）项目将开发一个动力学模型，以增强对昆虫飞行作为一个综合系统的理解，并将此信息应用于机器人设计。昆虫大小的飞行在能量上是非常具有挑战性的。尽管如此，飞行的进化刺激了我们今天看到的昆虫的进化多样性。昆虫能飞很长的距离，在拥挤和阵风的环境中机动，并克服扑翼飞行的能量限制，这在人类工程系统中还无法比拟。昆虫将有弹性的外骨骼连接到翅膀上，以帮助在每次拍打时储存和返回能量;然而，为了最大限度地获得能量回报，昆虫必须以稳定的速度拍打翅膀。该项目将探索昆虫如何将弹簧和翅膀结合在一起，以管理能量需求和在一系列条件下的飞行控制。该项目还将探索昆虫用于飞行的两种不同类型的肌肉收缩如何通过相同的基本力学和肌肉特性来实现，从而为理解昆虫如何实现这种不同类型的飞行提供数学框架。该项目将使用带有弹性外骨骼的机器人物理模型与翅膀和昆虫规模的扑翼机器人相结合，以建立一个通用的“弹簧-翅膀”框架。在这两个合作机构的研究将包括一个沉浸式的，垂直整合的本科研究计划。学生团队将在学年期间获得指导和现场研究经验，并将前往他们的交流地点进行跨学科的夏季研究。至少两名研究生和一名博士后研究员也将接受跨学科培训。昆虫规模的扑翼飞行需要高功率驱动和低延迟控制。为了减轻飞行动力的需求，大多数昆虫通过肌肉间接地驱动它们的翅膀，肌肉使坚硬的弹性外骨骼变形。将弹性元件耦合到翅膀允许昆虫潜在地作为共振系统操作，这将降低功率成本，但也将引入控制约束，例如限制翼振频率调制。为了给扑翼飞行提供动力，昆虫进化出了两种不同的驱动策略：同步飞行，由神经系统对拮抗肌肉进行时间周期性的强迫;异步飞行，肌肉由于应变依赖性激活而产生自激振荡。该项目将建立一个弹簧翼系统的分析框架，测试昆虫是否在其假设的共振频率下工作，并开发一个动态缩放的robophysical弹簧翼挡板，以探索一个单一的无量纲参数，Weis-Fogh数，如何影响弹性储能和气动力控制。然后将这两种肌肉驱动策略结合起来，测试从异步昆虫进化而来的同步飞行昆虫是否保留了自激（异步）振荡的必要生理特征。一个单一的动态系统，可以从两个政权的稳定扑翼过渡将在robophysical系统和在规模，生物启发扑翼机器人进行测试。最后，将研究在弹簧翼系统中处于或远离共振操作的权衡。该项目连接了生物科学和物理科学，将扩大对生理和生物力学原理以及飞行中所涉及的权衡的理解，并应通过应用于机器人技术来改变目前对昆虫飞行的理解。本科生和研究生以及博士后研究员将参加指导，跨学科研究团队，并将在国家科学会议上展示研究成果。研究成果还将通过生物启发设计讲习班传播。该奖项由土木，机械和制造创新部的动力学，控制和系统诊断计划，工程理事会以及综合有机系统部的生理机制和生物力学计划共同资助，该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准。

This Research Advanced by Interdisciplinary Science and Engineering (RAISE) project will develop a dynamical model to enhance understanding of insect flight as an integrated system and apply this information to robotic design. Flight at the size of insects is very energetically challenging. Nonetheless, the evolution of flight spurred much of the evolutionary diversity of insects we see today. Insects fly long distances, maneuver in crowded and gusty environments, and overcome the energetic limitations of flapping wing flight in ways that cannot yet be matched in human-engineered systems. Insects couple springy exoskeletons to their wings to help store and return energy on every flap; however, to maximize energy return, insects would have to beat their wings at a steady rate. This project will explore how insects couple springs and wings together to manage energy requirements and flight control under a range of conditions. This project will also explore how the two distinct types of muscle contraction that insects use to power flight could both be achieved with the same underlying mechanics and muscle properties, enabling a mathematical framework for understanding how insects achieve such different types of flight. The project will use robophysical models with springy exoskeletons coupled to wings and insect-scale flapping robots to establish a general “spring-wing” framework. Research at both collaborating institutions will include an immersive, vertically integrated undergraduate research program. Student teams will receive mentorship and on-site research experience during the school year and will travel to their exchange location for interdisciplinary summer research. At least two graduate students and a post-doctoral fellow will also receive cross-disciplinary training.Insect-scale flapping-wing flight demands both high-power actuation and low-latency control. To mitigate flight power requirements, most insects actuate their wings indirectly via muscles that deform a stiff, elastic exoskeleton. Coupling elastic elements to the wings allows insects potentially to operate as a resonant system, which would reduce power costs but also would introduce control constraints, such as limiting wingbeat frequency modulation. To power flapping flight, insects evolved two distinct actuation strategies: synchronous flight, with time-periodic forcing of antagonistic muscles paced by the nervous system, and asynchronous flight, in which muscles set up self-excited oscillations due to strain-dependent activation. The project will establish an analytic framework for spring-wing systems, test if insects operate at their hypothesized resonant frequencies, and develop a dynamically scaled robophysical spring-wing flapper to explore how a single non-dimensional parameter, the Weis-Fogh number, influences elastic energy storage and aerodynamic force control. The two muscle actuation strategies will then be combined, testing if synchronous flying insects that have evolved from asynchronous insects retain the necessary physiological signatures of self-excited (asynchronous) oscillations. A single dynamic system that can transition from the two regimes of stable flapping will be tested in the robophysical system and in an at-scale, bio-inspired flapping wing robot. Finally, the tradeoffs of operating at or away from resonance in spring-wing systems will be investigated. The project bridges the biological and physical sciences, will expand understanding of physiological and biomechanical principles and trade-offs involved in flight, and should transform the current understanding of insect flight, with applications to robotics. Undergraduate and graduate students and a post-doctoral fellow will participate in mentored, interdisciplinary research teams, and will present research results at national scientific meetings. Research results will also be disseminated through a bio-inspired design workshop. This award is co-funded by the Dynamics, Control and Systems Diagnostics Program in the Division of Civil, Mechanical and Manufacturing Innovation, Directorate for Engineering, and the Physiological Mechanisms and Biomechanics Program in the Division of Integrative Organismal Systems, Directorate for Biological Sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.