Aix Marseille Université, CNRS, ISM, Marseille , France.
J R Soc Interface. 2019 Jan 31;16(150):20180878. doi: 10.1098/rsif.2018.0878.
Many insects such as desert ants, crickets, locusts, dung beetles, bees and monarch butterflies have been found to extract their navigation cues from the regular pattern of the linearly polarized skylight. These species are equipped with ommatidia in the dorsal rim area of their compound eyes, which are sensitive to the angle of polarization of the skylight. In the polarization-based robotic vision, most of the sensors used so far comprise high-definition CCD or CMOS cameras topped with linear polarizers. Here, we present a 2-pixel polarization-sensitive visual sensor, which was strongly inspired by the dorsal rim area of desert ants' compound eyes, designed to determine the direction of polarization of the skylight. The spectral sensitivity of this minimalistic sensor, which requires no lenses, is in the ultraviolet range. Five different methods of computing the direction of polarization were implemented and tested here. Our own methods, the extended and AntBot method, outperformed the other three, giving a mean angular error of only 0.62° ± 0.40° (median: 0.24°) and 0.69° ± 0.52° (median: 0.39°), respectively (mean ± standard deviation). The results obtained in outdoor field studies show that our celestial compass gives excellent results at a very low computational cost, which makes it highly suitable for autonomous outdoor navigation purposes.
许多昆虫，如沙漠蚂蚁、蟋蟀、蝗虫、蜣螂、蜜蜂和黑脉金斑蝶，都被发现从线性偏振天光的规则模式中提取导航线索。这些物种在复眼的背缘区域配备了小眼，对天光的偏振角度敏感。在基于偏振的机器人视觉中，迄今为止使用的大多数传感器包括带有线性偏振器的高清 CCD 或 CMOS 相机。在这里，我们展示了一个由两个像素组成的偏振敏感视觉传感器，该传感器的灵感主要来自沙漠蚂蚁复眼的背缘区域，旨在确定天空偏振光的方向。这个极简主义传感器不需要透镜，其光谱灵敏度在紫外线范围内。这里实现并测试了五种不同的偏振方向计算方法。我们自己的方法，即扩展和 AntBot 方法，优于其他三种方法，平均角度误差仅为 0.62°±0.40°（中位数：0.24°）和 0.69°±0.52°（中位数：0.39°）（平均值±标准差）。在户外实地研究中获得的结果表明，我们的天文罗盘在非常低的计算成本下能取得出色的结果，非常适合自主户外导航应用。
