仿生定位系统

Insect Navigation

虽说全球定位系统彻底改变了我们的出行方式,很多动物其实也有自己的内置导航系统,比如蚂蚁和蜜蜂就自带导航。众所周知,蚂蚁和蜜蜂的眼睛对偏振光非常敏感。天空中的偏振光会呈现出一种特殊模式,这跟太阳的方位有关。爱丁堡大学的生物机器人学家芭芭拉说。

我们可以亲眼看到偏振光,拿一副偏光眼镜对着太阳旋转,就会看到透过镜片的光线发生改变。芭芭拉说,蚂蚁蜜蜂这些昆虫的眼球下面内置了很多这种偏振光感系统,你可以把它们想象成微小的偏振光定向滤镜,或者说,蚂蚁蜜蜂戴了很多副太阳镜,指向四面八方。

但芭芭拉好奇的是,日光为昆虫提供的信息是否足以让昆虫准确定位呢。于是她的团队仿照沙漠蚂蚁的眼睛做了一个传感器,放在模拟日光的人造光下,然后把传感器接收到的光信号输入计算机模型中,这些模型模拟了沙漠蚂蚁和蛐蛐的大脑,因为它们都有日光定向能力。研究人员发现,这些昆虫有与生俱来的感应力和处理器,可以精准感知方向,误差只有几度。这项研究发表在美国科学公共图书馆计算生物学杂志上。

有朝一日,基于昆虫定位能力的新型定位系统会变得又节能又便宜,甚至取代现有的全球定位系统。昆虫的大脑很小,跟钉子头一般大。那么小的脑袋,能耗极少,却比工程浩大的全球定位系统导航更好。目前,芭芭拉正在打造一款可以像沙漠蚂蚁一样利用光线定位的机器人,不过日落之后,这些机器人可能就得投石问路了。

原文

GPS has completely transformed how we get around. But other animals have long had their navigation systems built right in—like ants and bees. “We know their eyes are quite sensitive to polarized light, and the sky has a particular pattern of polarized light, relative to the position of the sun.” Barbara Webb, a bioroboticist at the University of Edinburgh.

You can see polarized light firsthand if you take a pair of polarized sunglasses and rotate them against the sky—the light passing through the lenses changes. Webb says the insects have polarization built into facets of their compound eyes. “You can think of it as the equivalent of having a little polarization directional filter over them or lots of sunglasses pointed in different directions.”

But Webb was curious whether there’s really enough information in the sky to give insects an accurate sense of direction. So her team built a sensor modeled after a desert ant eye and put it under artificial light meant to simulate the sky. They then fed that sensor input into a computational model meant to mimic the brains of desert ants, crickets and other insects with a celestial compass. And they found that with the insects’ innate sensing and processing equipment, they can likely sense compass direction down to just a couple degrees of error. The results are in the journal PLOS Computational Biology.

A system based on that of insects could someday be a cheap, low-energy alternative to GPS. “Insects have very tiny brains. A brain the size of a pinhead that’s using hardly any energy. And yet they’re still able to navigate better than we can with GPS, which is a huge infrastructure.” Webb is now working on building a robot that can, like the desert ant, use light to get its bearings. Although after sundown, it may have to ask for directions.

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