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GETTING ANSTY ABOUT NAVIGATION
AT SUPERFICIAL GLANCE, ants seem to alternate between random walks and purposeful straightline travel. Scientists at Aix Marseille University in Marseille, France, have created an AntBot that delves beyond the superficial and moves with ant-like multisensory fusion strategies.
“A 6-Legged Robot Stares at the Sky to Navigate Like a Desert Ant,” by Matt Simon, gives details in WIRED, February 13, 2019. Here are tidbits gleaned from the WIRED article, AAAS sciencemag.com, and my usual Internet sleuthing.
The Cataglyphis fortis desert ant navigates in the particularly harsh Sahara. Image by April Nobile/©AntWeb.org /CC BY-SA 3.0.
A Desert Ant with Uncommon Navigation. Many ant species depend upon dropping pheronome trails to mark their passage and return. However, extreme heat would destroy such chemical trails, and the Sahara desert ant Cataglyphis fortis has evolved a marvelous alternative means of navigation. Along its travels, the ant keeps track of polarization angles of the sun, its number of strides, and, like bees, the optic flow, the rate of ground travel. Such a multisensory fusion strategy is called path integration.
Ants Do It, So Why Not AntBots Too? Julien Dupeyroux and his colleagues at Aix Marseille University, Marseille, France, have devised an elegant analog of C. fortis path integration in their six-legged AntBot.
The AntBot. This and the following image from Dupeyroux et al, Sci. Robot. 4, EAAU0307 (2019) in WIRED.
According to the paper’s abstract, AntBot has “two optimal sensors equipped with just 14 pixels, two of which were dedicated to an insect-inspired compass sensitive to ultraviolet light. When combined with two rotating polarized filters, this compass was equivalent to two costly arrays composed of 374 photosensors, each of which was tuned to a specific polarization angle.”
Sensitivity to ultraviolet light gives AntBot its smarts, even in overcast conditions.
“The other 12 pixels,” the abstract explains, “were dedicated to optic flow measurements…. The mean homing error recorded during the overall trajectory was as small as 0.67 percent under lighting conditions similar to those encountered by ants. These findings show that ant-inspired PI [Path Integration] strategies can be used to complement classical techniques with a high level of robustness and efficiency.”
WIRED magazine’s Matt Simon writes, “To test it, the researchers programmed the robot to ‘forage’ much like a desert ant—that is, zig-zagging rather than going straight in one direction.”
At left, a typical round-trip of C. fortis; the thinner line, its outbound travel, the thicker one, its return. At right, an AntBot counterpart.
“In outdoor experiments,” Simon writes, “AntBot managed to travel almost 50 feet, yet divine its way back to its starting point with an accuracy of less than half an inch.”
AntBot’s Applications. “The idea moving forward, then,” Simon sums up, “is to adapt this system as a complement to other robotic senses, like traditional machine vision and lidar… Both are computationally and energetically expensive, but AntBot’s sensors are much less intensive—remember, it’s just two pixels watching for UV polarized light.”
Last, check out Elsa Chip’s fanciful YouTube posting of this at Robot Reporters.
A New Staff Member here at SimanaitisSays? I’m considering giving Elsa more assignments here at SimanaitisSays. I’ve always had a thing for blue-eyed blondes talking science. ds
© Dennis Simanaitis, SimanaitisSays.com, 2019
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