A pair of wheeled robots and a pair of drones, assembled by researchers at Carnegie Mellon University and Oregon State University, will work together to autonomously map and search an underground mine as competition begins this week in the $2 million DARPA Subterranean Challenge.

The first scored event in the multiyear competition, sponsored by the Defense Advanced Research Projects Agency, will take place Aug. 15–22 in a research mine operated by the National Institute for Occupational Safety and Health in South Park Township, outside Pittsburgh.

The Carnegie Mellon/Oregon State team, Explorer, is one of 11 teams DARPA has qualified to compete in the event, where the robots will face a mine disaster scenario. The robots will be scored on their ability to develop a 3D map of the mine and identify a variety of objects positioned in it, including simulated human survivors.

"This is a task that requires robot autonomy, perception, networking and mobility for us to be successful," said Sebastian Scherer, who leads the team with Matt Travers, both of whom are faculty members in CMU's Robotics Institute. "Underground operations pose many unique challenges for robots, but we've benefited from the Robotics Institute's depth of experience in developing robots that can work in enclosed spaces and dark, dank environments."

Geoff Hollinger, an assistant professor of mechanical engineering at Oregon State and a CMU robotics alumnus, will work with his students to provide additional expertise in multirobot systems.

The team, which includes about 30 faculty, staff members and students, has tested its robots and procedures extensively at the Tour-Ed Mine in Tarentum, Pennsylvania.

One of the team's major challenges has been maintaining communications between the robots and the human operator who oversees them from outside the mine, said Steven Willits, Explorer's lead test engineer. The rock walls block radio signals, which means radios are largely useless unless they are in line of sight with each other. So the ground robots, named Rocky 1 and Rocky 2, periodically drop Wi-Fi nodes on the mine floor, creating a communications network as they go.

Even so, the number of nodes they carry is limited, so the robots eventually must venture beyond their ad hoc network, operating autonomously to gather data, said Kevin Pluckter, a master's student in robotics who is the lead operator. The robots will relay that information back to the operator once they return within range of the Wi-Fi network.

Under DARPA's rules, the teams will have 60 minutes to complete their mapping and search missions. Both Rocky 1 and Rocky 2 can run the entire time, but the drones have more limited flight times. The drones will therefore be used when the ground robots meet an obstruction they can't surmount, flying ahead to complete the mission.

The Tunnel Circuit is one of three events leading up to the finals. An Urban Circuit, in which robots will explore complex underground facilities, will take place in February 2020; and a Cave Circuit will be in August 2020. A final event incorporating all three environments is scheduled for August 2021 and will determine the winner of the competition's $2 million grand prize.

The challenge will develop technologies needed by military and civilian first responders when faced with damaged underground environments suspected to be unsafe for humans.

Explorer competes in the Subterranean Challenge's systems track, in which the teams develop physical robotic systems that compete in live environments. But the challenge also includes a virtual track, in which teams develop software and algorithms to compete in simulation-based events. Nine teams began the virtual competition in July, and the winners will be announced during this month's event.

Explorer is one of seven teams that will receive up to $4.5 million to develop their hardware and software for the competition. The team is also sponsored by the Richard King Mellon Foundation, Schlumberger, Microsoft, Boeing, FLIR Systems, Near Earth Autonomy, Epson, Lord and Doodle Labs. Learn more about the team and sponsorships on the Explorer website.