The wings of flapping-wing micro aerial vehicles (MAVs) face the risk of breakage. To solve this issue, we propose the use of a biomimetic foldable wing. In this study, a resonant-driven piezoelectric flapping-wing actuator with a passive folding/unfolding mechanism was designed and fabricated, in which the folding/unfolding motion is passively realized by the centrifugal and lift forces due to the stroke motion of the wings. Although the passive folding/unfolding is a known concept, its feasibility and characteristics in combination with a resonant system have not yet been reported. Because the resonant actuation is necessary for extremely small, insect-scale MAVs, research is required to realize such MAVs with a foldable-wing mechanism. Therefore, we first examine and report the performance of the resonant-driven passive folding/unfolding mechanism. We also present a simplified theoretical model demonstrating an interaction between the resonant actuation system and folding/unfolding mechanism. We successfully demonstrate the folding/unfolding motion by the fabricated actuator. In addition, the theoretical model showed good agreement with the experiment.

中文翻译：

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共振驱动被动折叠/展开拍打翼执行器

襟翼微型飞行器（MAV）的机翼面临断裂的风险。为了解决这个问题，我们建议使用仿生可折叠机翼。在这项研究中，设计并制造了一种具有被动折叠/展开机构的共振驱动压电襟翼执行器，其中，由于机翼的冲程运动而产生的离心力和升力被动地实现了折叠/展开运动。尽管被动折叠/展开是已知的概念，但尚未报道其与共振系统结合的可行性和特征。由于共振致动对于极小昆虫规模的MAV是必需的，因此需要进行研究以实现具有可折叠翼机构的MAV。因此，我们首先检查并报告共振驱动的被动折叠/展开机制的性能。我们还提出了一个简化的理论模型，展示了共振驱动系统和折叠/展开机制之间的相互作用。我们成功地演示了由制造的执行器进行的折叠/展开运动。此外，理论模型与实验结果吻合良好。