Controlled flight of a microrobot powered by soft artificial muscles
Controlled flight of a microrobot powered by soft artificial muscles
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DOI：
10.1038/s41586-019-1737-7
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发表时间：
2019-11-14
期刊：
影响因子：
64.8
通讯作者：
Wood, Robert J.
中科院分区：
文献类型：
--
作者：
Chen, Yufeng;Zhao, Huichan;Wood, Robert J.
能够在高度杂乱的自然环境中航行的飞行昆虫可以承受飞行中的碰撞，因为它们的低惯性（1）和翅膀（2）、外骨骼（1）和肌肉的弹性相结合。目前的昆虫级（长度小于10厘米，重量小于5克）空中机器人（3-6）使用刚性微型致动器，这些致动器在外部冲击下通常是脆弱的。能够大变形的仿生人造肌肉（7-10）提供了用于致动的有希望的替代方案，因为它们可以承受由这种冲击引起的应力。然而，现有的软致动器（11-13）还没有表现出足够的功率密度来实现离地，并且它们的致动非线性和有限的带宽对实现闭环（由基于感觉反馈调整的输入控制信号驱动）飞行控制产生了进一步的挑战。在这里，我们开发了由柔软的人造肌肉提供动力的比空气更好的空中机器人，这些机器人展示了开环（由预定的信号驱动，没有反馈），被动稳定（飞行期间直立）的上升飞行以及闭环，悬停飞行。这些机器人由多层介电弹性体致动器驱动，每个致动器重100毫克，谐振频率为500赫兹，功率密度为每公斤600瓦。为了增加致动器的机械功率输出并演示飞行控制，我们提出了克服软致动器特有的挑战的方法，例如非线性转导和动态屈曲。这些机器人可以感知和承受与周围障碍物的碰撞，并可以通过利用材料的鲁棒性和车辆的被动稳定性从飞行中的碰撞中恢复。我们还在混乱的环境中同时驾驶两个微型飞行器。它们与墙壁和彼此碰撞而不遭受损坏。这些机器人依靠非机载放大器和外部运动捕捉系统为介电弹性体致动器提供动力并控制它们的飞行。我们的工作展示了软致动器如何实现足够的功率密度和带宽，以实现受控飞行，说明了开发下一代敏捷软机器人的潜力。
Flying insects capable of navigating in highly cluttered natural environments can withstand in-flight collisions because of the combination of their low inertia(1) and the resilience of their wings(2), exoskeletons(1) and muscles. Current insect-scale (less than ten centimetres long and weighing less than five grams) aerial robots(3-6) use rigid microscale actuators, which are typically fragile under external impact. Biomimetic artificial muscles(7-10) that are capable of large deformation offer a promising alternative for actuation because they can endure the stresses caused by such impacts. However, existing soft actuators(11-13) have not yet demonstrated sufficient power density to achieve lift-off, and their actuation nonlinearity and limited bandwidth create further challenges for achieving closed-loop (driven by an input control signal that is adjusted based on sensory feedback) flight control. Here we develop heavier-than-air aerial robots powered by soft artificial muscles that demonstrate open-loop (driven by a predetermined signal without feedback), passively stable (upright during flight) ascending flight as well as closed-loop, hovering flight. The robots are driven by multi-layered dielectric elastomer actuators that weigh 100 milligrams each and have a resonance frequency of 500 hertz and power density of 600 watts per kilogram. To increase the mechanical power output of the actuator and to demonstrate flight control, we present ways to overcome challenges unique to soft actuators, such as nonlinear transduction and dynamic buckling. These robots can sense and withstand collisions with surrounding obstacles and can recover from in-flight collisions by exploiting material robustness and vehicle passive stability. We also fly two micro-aerial vehicles simultaneously in a cluttered environment. They collide with the wall and each other without suffering damage. These robots rely on offboard amplifiers and an external motion-capture system to provide power to the dielectric elastomer actuators and to control their flight. Our work demonstrates how soft actuators can achieve sufficient power density and bandwidth to enable controlled flight, illustrating the potential of developing next-generation agile soft robots.