DARPA’s Subterranean Robot Explorers


Team CoSTAR’s NeBula-Spot robot in the caverns. Credit: NASA/JPL-Caltech

Pranav Pamula, General

A few days ago, four-legged mechanical beasts were stalking vast caverns under the city of Louisville, Kentucky, trekking through ordeals of dust and smoke with a single-minded determination. Fortunately, their mission did not entail exterminating the last survivors of a robotic invasion. Instead, it was a mission set to them by the various participants in DARPA’s (Defense Advanced Research Projects Agency) latest challenge, which aimed to prove the viability of robots in dangerous subterranean environments.

DARPA held this competition to develop robots which would facilitate search-and-rescue missions in mines, post-earthquake wreckage, caves, and other such scenarios where it would be dangerous or impossible for a human to perform the task. The machines were tasked with finding “artifacts” placed by DARPA while dealing with smoke and difficult terrain.

The competition has been active for three years, as competitors from around the world have vied to create a versatile team of robots and claim a part of the $5,000,000 in total prizes at the end of the journey. But the competition wasn’t just one of grinding metal joints in grimy caverns; a secondary competition with separate teams took place in the virtual world, in an advanced simulation of the real events.

The first trial, the Tunnel Circuit, took place in August of 2019, as the robots navigated winding, multilayered tunnels. The second trial, the Urban Circuit, took place in February of 2020, as they explored sprawling subway systems. The Systems Competition of the third trial, the Cave Circuit, was cancelled due to the ongoing COVID-19 pandemic, but that doesn’t mean the robots’ virtual counterparts weren’t voyaging through caverns of code in November of 2020! 

And finally, on September 21-23 of 2021, the final event took place in the Mega Cavern in Louisville, Kentucky. Elements from all three trials were incorporated in order to provide the ultimate challenge to the robots. Eight competitors battled in the Systems Competition, while twelve participated in the Virtual Competition.

It was an impressive display of technology: squads of quadrupedal robots, as well as drones, rapidly mapped out their environments and reported their locations while searching through dense smoke, rough terrain, and narrow passages. One of the competitors, the Australian research organization CSIRO, stated before the final event that they would “create 3D maps of underground environments through LiDAR (Light Detection and Ranging) scanners mounted on legged robots as well as unmanned aerial vehicles which can fly in GPS-denied environments without a human controller.”

The winner of the Systems Competition, with 23 points, was a team from the University of Nevada, Reno, and their CERBERUS robots. The set of robots consisted mainly of four ANYmal C Legged robots; they walked away with $2,000,000. Team Dynamo, meanwhile, won the Virtual Competition, with 223 points, winning $750,000.

DARPA has held many competitions in the past. From 2004 to 2007, they held the Grand Challenges, a series of races between self-driving cars, which spurred on the development of autonomous vehicles. The Subterranean Challenge may lead to similar advancements in technology. In any case, DARPA will certainly continue to hold these pioneering competitions in the years to come.





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