Without GPS, This Robot Shows How The Sun's Position Can Be Used To Navigate Anywhere

Researchers in France have just built a robot they're calling the "AntBot'. Yes it's a little small, yes it has six legs that scurry along, but those aren't the real reasons for the name.

That comes from the robot borrowing the navigation skills of the desert ant.

Images courtesy: CNRS

The reason building autonomous robots is so complex is because of how many factors are involved. Just moving around requires spatial awareness, object detection, GPS tracking. In this case though, the researchers wanted a robot that could move around without needing GPS.

The 9-inch robot is creation of researchers at the Aix-Marseille University. They chose legs instead of wheels because, though slower, are more suited to traversing rough terrain. The key part of their creation however is a set of navigational tools borrowed from two species of ants: the Cataglyphis fortis of the Sahara and Melophorus bagoti of Central Australia.

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Julien Dupeyroux, lead author on the paper,explains how these desert ants travel great distances in search of food. The thing is, other ants can find their way home by following the smell of the trail of pheromones they leave. However, the scorching heat of the desert makes this tactic useless, so the ants there have had to adapt. Instead, they use a combination of tactics scientists call "path integration".

One of these tactics makes use of their compound eyes, which contain photoreceptors sensitive to UV light from the Sun that's polarized by scattered air molecules. Specifically though, these polarization patterns change as the sun moves across the sky. The ants have actually learned how to track these shifting patterns to figure out the position of the sun, and therefore the direction they're moving in.

Another feat they make use of is tracking how fast the image of the ground moves across their eyes, called optic flow. You know how if you look out a speeding car's window at stuff just a few feet away, it blurs past unless you turn your head to focus on it? It's basically that. Ants can use this optic flow, in combination with the knowledge of how many steps they've taken, to estimate how far they've travelled.

So when you put an internal compass together with a distance tracker into a robot, what you get is a mobile homing device. In testing, the team sent out the Raspberry Pi-powered bot to randomly walk around a short time, before commanding it to return home. No matter the terrain though, the AntBot was near flawless at finding the shortest route back

This could be huge towards building robots in the future, knowing we don't necessarily need to equip them all with GPS if they're always going to be returning to a specific point. Additionally, this thing was cheap as heck to build.

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The team previously estimated building the sensors would cost around $85,000. They were however able to significantly drive the cost down using cheaper materials and sensors, completing their build with just $5,00, or approximately Rs 35,600.

"Though the GPS has a great impact in worldwide navigation, it suffers from several limits," Dupeyroux said. "These include signal failure when around tall buildings; a relatively small area of accuracy for smaller devices like smartphones, and not being particularly good on cloudy, rainy, or snowy days. The AntBot and robots like it should, at least in theory, be able to work around these limits.