When we need to navigate today, even if that's finding a building a few streets away, GPS is the go to technology.
Of course it is, seeing as we've gone way past navigating by the sun and stars and using a simple compass. But what do you do when your GPS fails?
Because GPS does occasionally fail. It relies on signals from multiple positioning satellites, orbiting about 20,000 km above the Earth. There are currently 73 of them in orbit, and your device can receive a handful of signals at any given time. But if there's something large enough to block these signals, like a tunnel or tall buildings, the positioning system can fail.
If you're just trying to find your way in a new city, it's a serious nuisance. But if you're for instance, an emergency responder, it could mean the difference between life and death. That's why researchers have been exploring other means of navigation that are more consistent.
One of those alternative means has been developed by researchers at the Aix-Marseille University in France. They've developed something they call the AntBot. Sure, it has six legs and moves by scurrying along on them. But the real reason it got that name is because of how it navigates.
The robot uses navigational tools inspired by two species of desert ants: the Cataglyphis fortis of the Sahara and Melophorus bagoti of Central Australia. Julien Dupeyroux, lead author on the paper, explains how these desert ants travel great distances in search of food.
Usually, ants leave a trail of pheromones they can follow back home, and other ants can follow to the food source. Except, the scorching heat of the desert makes this useless. So instead, these ants have adapted to using something scientists call "path integration".
The AntBot -?French National Center for Scientific Research
The compound eyes these desert ants possess contain photoreceptors sensitive to ?UV radiation scattered by molecules in the air. That means they can figure out the position of the sun in the sky (based on the changes in polarization patterns), and therefore what direction they're going.
Additionally, these ants can actually track how fast the image of the ground is moving past their compound eyes to estimate the speed they're going. 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 with an internal compass combined with a distance tracker, the ants always know exactly how far away they are from home base. Put those capabilities into a robot like the AntBot, and you get a mobile unit that can always make its way home
Then there's a group at the University of Sussex, that have developed a system that perfectly complements that of AntBot, one that relies on visual navigation.
University of Sussex researcher and roboticist Andy Philippides and his team discovered that, when these desert ants travel away from the nest, they periodically stop and scan the environment before moving on. They've figured out that these ants are sort of committing visual snapshots of the area to memory as they go. So in addition to their other navigation, when returning they're also following a trail of familiar surroundings back to their home
As such, Philippides and his team are working on a robot that can follow a familiar path home, just like you would when you first move to a new city.
Now, it's not just that these technologies could be used for navigation without GPS, or for autonomous robots, though that's obviously the case. Scientists also consider these discoveries to be invaluable for when we want to start mapping the Moon or Mars from ground zero. Both of those are far away from the GPS satellites we find so integral here on Earth.
But on Mars, we could just send a robot that maps the surroundings as it wanders aimlessly. And when it's time to turn back, all it has to do is follow its internal compass home, without the need for a dedicated satellite.