Flow visualisations are essential to better understand the unsteady aerodynamics of flapping wing flight. The issues inherent to animal experiments, such as poor controllability and unnatural flapping when tethered, can be avoided by using robotic flyers that promise for a more systematic and repeatable methodology. Here, we present a new flapping-wing micro air vehicle (FWMAV)-specific control approach that, by employing an external motion tracking system, achieved autonomous wind tunnel flight with a maximum root-mean-square position error of 28 mm at low speeds (0.8–1.2 m/s) and 75 mm at high speeds (2–2.4 m/s). This allowed the first free-flight flow visualisation experiments to be conducted with an FWMAV. Time-resolved stereoscopic particle image velocimetry was used to reconstruct the three-dimensional flow patterns of the FWMAV wake. A good qualitative match was found in comparison to a tethered configuration at similar conditions, suggesting that the obtained free-flight measurements are reliable and meaningful.

中文翻译：

---

扑翼机器人的精确位置控制，实现风洞中自由飞行的流动可视化

流动可视化对于更好地理解扑翼飞行的非定常空气动力学至关重要。动物实验固有的问题，例如可控性差和系绳时不自然的拍打，可以通过使用机器人传单来避免，这些传单有望提供更系统和可重复的方法。在这里，我们提出了一种新的扑翼微型飞行器 (FWMAV) 特定控制方法，通过采用外部运动跟踪系统，在低速下实现最大均方根位置误差为 28 mm 的自主风洞飞行(0.8–1.2 m/s) 和 75 mm 高速 (2–2.4 m/s)。这允许使用 FWMAV 进行第一次自由飞行流可视化实验。时间分辨立体粒子图像测速法用于重建 FWMAV 尾流的三维流动模式。