NRI: Development of Autonomous Sub-Gram Flapping-Wing Artificial Flyers Using Novel Combustion-Driven SMA-Based Actuators

这个项目解决了实现可机动的、自主的、不受束缚的、昆虫规模的飞行机器人的核心动力和控制问题。即使是最好的小型电池，单位质量储存的能量也足够低，飞行时间最多只有几分钟。此外，当考虑到电池必须以很高的速度提供能量时，有翼的微型机器人是否甚至可以举起自己的重量都是值得怀疑的。相反，这个项目模拟了自然界中的飞行昆虫，它们使用动物脂肪作为燃料，其能量密度大约是最先进的电池的100倍。因此，该项目将展示液体燃料催化燃烧发动机，预计能够提供超过90分钟的动力飞行。这一结果将通过昆虫尺度的空气动力学、燃烧和飞行的创新集成建模、分析、设计、制造和控制来实现。例如，将昆虫规模的飞行机器人应用于人工授粉、搜救行动和田间生物学研究将产生更广泛的影响。该项目将间接产生新的能量转换方法、新的控制合成算法和制造技术，适用于广泛的轮式、有翼和腿式微型机器人。为了实现项目目标，该研究在三个具体领域取得了进展：(I)从生物启发设计和制造高效气动扑翼微型飞行器，其中来自自然的原理被转化为机器人设计，采用系统和控制的概念框架。在这个框架中，使用输入输出建模和系统辨识等工具分析了空气动力学、动力、设计和控制之间的相互作用；(Ii)使用基于燃料的形状记忆合金机制的机械执行，其中无焰催化燃烧产生诱导材料相变所需的热量，这是产生机械功所必需的；(Iii)控制，它自然产生于前两个领域，因为新的空气动力学高效设计需要发明用于稳定飞行的新控制策略和用于控制器合成的新技术。同样，新的驱动技术需要发明新的低级、物理上可实现的控制器。在这种情况下，燃烧驱动的执行器和扑翼机构的动力学是非线性和时变的，因此很大一部分研究工作致力于开发和实时实现新型的鲁棒稳定的非线性和自适应控制器。

This project addresses power and control questions central to achieving maneuverable, autonomous, untethered, insect-scale, flying robots. The amount of energy stored per unit mass in even the best small batteries is low enough that flight times would be limited to at most a few minutes. Furthermore, when the high rate at which the battery must supply energy is considered, it is questionable whether a winged microrobot could even lift its own weight. Instead, this project emulates flying insects in nature, which use animal fat as fuel, with an energy density about 100 times greater than state-of-the-art batteries. Accordingly, this project will demonstrate liquid-fuel catalytic combustion engines expected to be capable of over 90 minutes of powered flight. This result will be achieved through innovative integrated modeling, analysis, design, fabrication, and control of insect-scale aerodynamics, combustion, and flight. Broader impacts will arise from application of insect-scale flying robots to, for example, artificial pollination, search-and-rescue operations, and field biological research. Indirectly, this project will produce new methods for energy conversion, novel algorithms for control synthesis, and fabrication techniques, applicable to a wide gamut of wheeled, winged, and legged microrobots.To accomplish the project goals, the research advances knowledge in three specific areas: (i) biologically inspired design and fabrication of aerodynamically efficient flapping-wing microflyers, where principles from nature are translated into robotic designs, employing a systems-and-control conceptual framework. In this framework, the interaction between aerodynamics, power, design, and controls is analyzed using tools such as input-output modeling and system identification; (ii) mechanical actuation using fuel-powered shape-memory-alloys-based mechanisms, where flameless catalytic combustion generates the heat required to induce material phase transitions, necessary for the production of mechanical work; (iii) control, which emerges naturally from the first two areas as new aerodynamically efficient designs require the invention of novel control strategies for stable flight and new techniques for controller synthesis. Similarly, new actuation technologies require the invention of new low-level, physically implementable controllers. In this case, the dynamics of the combustion-driven actuators and flapping mechanisms are nonlinear and time-varying, reason for which a significant part of the research effort is dedicated to the development and real-time implementation of novel robustly stable nonlinear and adaptive controllers.