Moths have an eyesight to be envied. They can fly, hover, find flowers and collect nectar in almost absolute darkness. It’s an impressive feat since most diurnal creatures can barely walk (or fly) a straight line in the dark without bumping into some solid surface.
A team of researchers have recently decided to put an end to the mystery and investigate just how moths are able to function so well in the absence of light. They hope that they can someday apply the same mechanism to robots and create ones that can safely navigate dark spaces without crashing into anything.
The study, published last Thursday (June 11, 2015), in the journal Science, revealed that the hawkmoth (Manduca sexta), a large moth that feeds on a flower by hovering next to it, commonly found in North America, pays attention to the flower’s movements and constantly uses them as a guide for its own actions.
It also pays attention to the lighting conditions and adjusts its eyes not unlike how a photographer adjusts a camera’s aperture.
Simon Sponberg, lead author of the study and assistant professor at Georgia Tech University, gave a statement informing that between midday and midnight, light changes by no less than 10 billion fold. He explains that it’s one of the most variable quantities that animals have to deal with in the natural world.
Professor Sponberg went on to explain that what the hawkmoth essentially does is change the speed of the visual processing parts of its brain. It exposes its visual system to light for longer periods of time, before needing to act on the information. There’s a good number of frames being taken sequentially, and these frames get exposed to light for a significantly longer period of time.
However, recreating this mechanism in robots may not be as quick or simple as the scientists initially hoped as timing is everything. If a hawkmoth exposes the frames to light for too long, they start to get blurred together and the eyesight drops in quality.
If a hawkmoth goes too slow, it stops being able to track any movement. Professor Sponberg shared: “We found that the moths are doing this, but they’re only doing it to a point and that point is very special. They’re only slowing down their brain to the point where they are able to track the movements of natural flowers. And so they seem to be tuned to the demands of their natural environment”.
To prove that hawkmoths would find it hard to follow fast object when they slowed down their brains in order to let in more light, Sponberg and his team created a robotic flower that they could control when it came to the speed it was moving at.
The researchers found that most of the frequencies (94% of them) that flowers moved at in the wind were below 1.7 Hz and hawkmoths proved go be good at tracking flowers that in poor lighting conditions that moved at frequencies below 2 Hz.
However, they performed quite poorly when the robotic flower moved at high speeds. They lost their ability to accurately track the flower. Eric Warrant, a professor at Lund University (Sweden) and an expert in the field of animal vision, was not disappointed by the finding and stressed that during the process of evolution, the sensory and the muscular abilities that species get are very specifically designed to match the tasks that they have to perform in their world.
The next step for the team is to go look at the brain of hawkmoths and try to get a better understanding of the mechanism that they employ.
If they are successful in fully understand how the insect works, the Air Force Center of Excellence on Nature-Inspired Flight Technologies and Ideas would be very interested in developing robots that can function in the same range of conditions as the hawkmoth.
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