Since prehistoric times, humans have navigated Earth by way of the sky. Like clockwork, the sun traces a predictable path from east to west every day. After sunset, stars emerge. Though complicated to decipher, constellations are recognizable in their patterns and offer an intricate map of the inverted world, which a trained navigator can use for precise pathfinding.
Celestial navigation is something of an anachronism, like quill pens and powdered wigs. GPS is today’s go-to system — and it’s great until it doesn’t work. Researchers at universities and some of the world’s top tech companies are developing advanced navigational techniques designed to fill in the gaps when GPS fails. For inspiration, many are looking towards desert ants, whose unique navigational abilities have been honed by evolution. Although still in their experimental phases, these systems could someday be used to bolster satellite-based navigation or even make it obsolete.
Limitations of GPS
If you’ve ever tried to use GPS while traveling through a tunnel or in the shadow of tall buildings, you’ve likely run into one of the system’s frustrating shortcomings. That’s because GPS (and similar systems like the European Union’s Galileo and the Russian’s GLONASS) relies on signals from multiple satellites orbiting Earth at up to 12,000 miles away. There are about 73 GPS satellites currently in orbit and, at any one time, a handful of them can ping a device almost anywhere on Earth. But if a large enough object blocks a clear line of communication, GPS navigation becomes inoperable.
A dropped signal is a minor irritation if you’re late for a meeting in an unfamiliar city but, for first responders and search-and-rescue teams, it could mean the difference between life and death. These aren’t the only people interested in such a system. GPS-free navigation could help the moon’s next visitors — be they humans or robots — map the alien world or ensure self-driving never lose track of where they’re going.
Nature is a treasure trove when it comes to inspiration for designs of new technologies, and navigational systems are no exception. For the past four decades, researchers at the Aix-Marseille University in France have designed and refined a series of sensors inspired by insect vision. The latest iteration of their work is AntBot, an autonomous robot with a navigation system based on the unique senses and pathfinding abilities of desert ants.
While navigating, desert ants are able to measure their orientation through celestial, patterned light.
“Desert ants can walk up to one kilometer (0.6 miles) within 30 minutes, and they can return to the entrance of their nest without risk of getting lost,” Julien Dupeyroux, an engineer at the Aix-Marseille University who worked on AntBot, told Digital Trends. “We wanted to investigate how to make this kind of navigation work in robots.”
Partnering with the French National Center for Scientific Research, Dupeyroux and his team developed a robot which, like desert ants, is equipped with UV light sensors capable of detecting bands of polarized light, which it uses to navigate like a “celestial compass.”
“While navigating, desert ants are able to measure their orientation through celestial, patterned light,” he explained. “When entering the atmosphere, the sunlight gets scattered by the atmosphere and this results in a specific pattern of polarization, which is symmetric according to the location of the sun. The ants can use this to get their orientation.”
As an added measure, AntBot is capable of counting its steps to determine its rate of movement relative to the sun. These combined aspects help it pinpoint its location with a precision of up to one centimeter (0.4 inches) per 14 meters (45 feet) traveled. Compare that to the accuracy of about five meters (16.4 feet) for civilian GPS. Dupeyroux thinks his system could be used in vehicles as onboard compasses or delivery drones for last-mile delivery.
AntBot isn’t the only robot using desert ant-inspired navigation. Researchers at the University of Sussex have developed a system that can function without GPS by using algorithms that mimic the desert ants’ brain.
” … Ants may learn the visual information of a route as it appears to them on their first time traversing it.”
The Sussex system is complimentary to AntBot, according to University of Sussex researcher and roboticist Andy Philippides. Where AntBot emphasizes path integration (i.e. combining its celestial compass with counting steps), the Sussex system relies on visual navigation.
In the lab, Philippides and his team studied how desert ants navigate so precisely and discovered that the ants tend to stop and scan in multiple directions as they travel beyond their nest. This behavior led the researchers to conclude that the ants use distinct snapshots of the world to help orient themselves and decide which path to take.
In other words, to get back their nests, desert ants follow a sort of bread-crumb trail of familiar snapshots, until they arrive at a location that visually resembles home. Philippides calls his system “familiarity-based navigation.”
“What this means is, ants may learn the visual information of a route as it appears to them on their first time traversing it,” he said. “If they’re then later near the route, they try to orient themselves until something looks familiar.”
Philippides and his team used these findings to develop a machine learning program integrated into a robot that records views it sees along the way. To find its way home, the robot simply uses snapshots to trace its path backwards.
AntBot and the Sussex system demonstrate just two ways in which navigation can be achieved without GPS. There are others. Researchers at Nvidia are working on a drone navigation system that uses GoPro footage from hiking trails to travel autonomously through wooded areas. In one trial, the drone navigated along a wooded trail without GPS for a little over half a mile.
Students from the University of Utah are working on a system that includes an array of sensors attached to a boot that can estimate a wearer’s position with an accuracy of about five meters, similar to a GPS but without the need for satellites. Such a system could help soldiers or explorers orient themselves when deep in unfamiliar territory.
And researchers from the SETI (Search for Extraterrestrial Intelligence) Institute and Astrobotic Technology recently used a used a Lidar-equipped drone to make a 3D map of the interior of a lava tube ice cave in Iceland. The researchers think the technique could be used to autonomously map lunar caves without depending on GPS.
These systems have their limitations. AntBot, for example, isn’t yet waterproof and hasn’t been calibrated to work at night. The Sussex system has to traverse a given route before it can learn travel that route again. And none of these methods have passed the experimental phases.
That said, as researchers continue to refine these new navigational systems, it could be one small step for ants, one giant leap for mankind.
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