DARPA’s Subterranean Challenge aims to make cave exploration a more robotic affair.

Outside its cavernous passageways, the mine’s entrance is emblazoned in red lettering that reads “Safety Research Coal Mine.” This site is just one of two mine systems at the Bruceton Research Center in Pittsburgh. They were once part of a full mine system but were split apart for research purposes after the U.S. Bureau of Mines leased 38 acres of land from the Pittsburgh Coal Company in 1910.

For more than a century, the U.S. government has been using these facilities to create and assess technologies that will help keep miners safe. The National Institute of Occupational Safety and Health’s (NIOSH) Pittsburgh Research Laboratory tests everything you could imagine, from how coal dust behaves to how to improve rescue missions when disaster strikes.

But tests were put on hold for eight days this August. Instead, the mines served as a testbed for the Defense Advanced Research Projects Agency’s (DARPA) latest endeavor: The Subterranean Challenge, or Sub-T for short.



“The Boss,” a driver-less automobile

Developed by General Motors and Carnegie Mellon University, “The Boss” won the DARPA Urban challenge in 2007 with an inventive use of LIDAR, radar, and GPS mapping.

It’s certainly not the first time DARPA has put out a challenge to the public. In 2007, DARPA kickstarted the autonomous vehicle industry with the Urban Challenge, where teams built self-driving vehicles capable of “performing complex maneuvers such as merging, passing, parking, and negotiating intersections.”

Then in 2015, the DARPA created the Robotics Challenge in direct response to the humanitarian crisis during the nuclear disaster in Fukushima, Japan, four years earlier. The ultimate aim was to create robots with “sufficient dexterity and robustness to enter areas too dangerous for humans” and to mitigate impacts of natural disasters.


A robot on a climbing ladder task at the DARPA Robotics Challenge Trials.

 And the Sub-T challenge has similar lofty expectations. DARPA designed the challenge to “better equip warfighters and first responders to explore human-made tunnel systems, urban underground, and natural cave networks, while decreasing risk to human lives.”

Why caves? The U.S. Army, for example, began preparing for underground warfare in North Korea’s extensive tunnel system across the demilitarization zone. Inside, the tunnels reportedly contain not only pathways, but also artillery and nuclear, chemical, and biological weapons.

It makes sense, then, that DARPA—an outfit dedicated to armed forces research—would create such a challenge for the top minds in artificial intelligence and robotics to tackle.


Officially, the DARPA website says the Sub-T Challenge “seeks novel approaches to rapidly map, navigate, and search underground environments during time-sensitive combat operations or disaster response scenarios.”

The ultimate goal of the tunnel challenge is for teams to remotely map, identify and report the greatest number of artifacts along the mines’ passages. Teams had to provide the exact coordinates of the items.

Over the course of four days, the eleven teams took turns making runs through the two on-site mines. Each team got two full attempts, from start to finish, and the clock runs out after one hour.

Each time, teams can run their robot fleet into and out of the cave up to four times—which is good because things could break.

Teams are told what they’re looking for in advance, which include a red backpack, mannequins, fire extinguishers and drills. There were about 10-30 artifacts in total and the locations of each changed in between each team’s turns.

The contest was first announced in December 2017, so teams had less than two years to concoct their plans and build out the hardware they hoped would best work in all three circuits.

After all, it’s unwise for teams to start from scratch between the three challenges, Dr. Timothy Chung, the program manager for the Sub-T Challenge, told Popular Mechanics. But they can—and should—take the lessons learned from the tunnel challenge and adapt their approaches accordingly.

Over time, teams learned how well their robots could withstand the tactical challenges that DARPA put inside the mines.

During those sweltering August days, eleven teams vied for the $200,000 prize (and the included robotic street cred)

Via Popular Mechanics