FOCUS JAN2020: Research & Development

Developing robots for underground exploration 16 Jan 2020

Patrick Reynolds for TunnelTalk

A variety of wheeled, legged and tracked robots, and aerial drones, are taking part in a multi-year competition run by the USA Defense Advanced Research Projects Agency (DARPA) and aimed at uncovering the most advanced remotely operated technologies available to support research and development for warfare and rescue roles in a range of underground conditions.

Robots explore tunnels in development competition
Robots explore tunnels in development competition

The competition began in 2019 and the next stage is scheduled for February 2020, with further stages running to late 2021. In addition to the physical robotic race in its Subterranean (SubT) Challenge, DARPA is also running a virtual competition involving software only, to take-on simulated tunnel circuits.

The first leg of the competition in real tunnels took place over eight days in August 2019 at the National Institute for Occupational Safety and Health research mines at Park Township, Pittsburgh, Pennsylvania. Teams came from eight countries to test their robotic designs. Some teams are DARPA-funded while others are privately supported and eligible for the prize money if they secure a top five ranking in a leg of the SubT Challenge.

Large-wheeled robot won the first stage
Large-wheeled robot won the first stage

The technologies used included small ground-moving robots, ranging from wheels and tracks to stilt-legs, and aerial drones, including rotor blades and a blimp balloon. Teams used combinations of the technologies to autonomously travel along two small mine tunnels and, with a variety of sensors, map the underground layout and search for targets.

Conditions included travelling through mud and water, and the robotic systems had to communicate among themselves as well as with the base station team at the tunnel portal. Team members were not allowed in the tunnels during the robotic runs and had to operate their robots from the portal.

A total of 64 ground robots and 21 drones took part in the first leg of the SubT Challenge. The robotic systems of each team had four runs in the mine tunnels, for an hour each time.

First leg results

The winner of the first leg was a large-wheeled miniature truck design by a joint venture of the USA Universities Carnegie Mellon and Oregon State, and supported by industry including Schlumberger. The Team Explorer JV is one of 11 teams reach the underground stage of the competition where points are awarded in each leg.

The competition runs for two years
The competition runs for two years

Team Explorer is funded by DARPA and its design focus was to produce a robust and modular system.

Over its two best runs on the tunnel circuit, the robotic system pulled in a tally of 25 points, more than twice as many as its nearest rivals. It also claimed the top spot in accuracy of target location.

“Mobility was a big advantage for us, ” said joint team leader Sebastian Scherer of Carnegie Mellon Robotics Institute. “We had big wheels and lots of power.”

Second place in the first leg went to Team CoSTAR, Collaborative SubTerranean Autonomous Resilient Robots, with another four wheel-based ground robot system. This team comprises NASA plus CalTech, MIT and KAIST, formerly the Korea Advanced Institute of Science and Technology. The team is funded by DARPA and gained a total of 11 points in the first leg.

First stage winner: Team Explorer
First stage winner: Team Explorer

NASA’s involvement in the underground competition lends an off-earth aspect to the race. The organisation says that it is considering using subsurface environments to train its own research efforts to search for traces of life elsewhere. The NASA Jet Propulsion Laboratory, which is managed at CalTech, is a key player in CoSTAR. This multi-robot system draws upon developments with other equipment it has for cave exploration and other applications.

In third place was Team CTU-CRAS, which, as the highest ranking privately-funded group and the only one with a top-five place, benefited from the prize money of US$200,000 available for this leg of the race. The CTU-CRAS team is a Czech-Canadian JV of Czech Technological University and Universite Laval.

Wider competition

Completing the top five rankings were two further DARPA-funded teams in fourth and fifth places, Team MARBLE from the University of Colorado and Scientific System Co, and Team CSIRO Data61 of USA Georgia Institute of Technology with the Commonwealth Scientific and Industrial Research Organisation and Emesent of Australia, with nine and seven points respectively.

First stage runner-up: Team CoSTAR, including NASA
First stage runner-up: Team CoSTAR, including NASA

The other teams in the first leg, collecting five or fewer points, are:

  • CERBERUS from the Universities of Nevada (Reno) and California (Berkeley) with ETH Zurich in Switzerland, Swiss firm Flyability, and Sierra Nevada Corp. The team is DARPA-funded.
  • NCTU of self-funded National Chiao Tung University of Taiwan with the blimp drone.
  • Robotika a self-funded Czech, USA and Swiss team of Robotika International, Czech University of Life Science, the Centre for Field Robotics in the Czech Republic, and Cogito Team from Switzerland. .
  • CRETISE the DARPA-funded team of Endevor Robotics and Neya Systems.
  • PLUTO a DARPA-funded team comprising University of Pennsylvania, Exyn Technologies and Ghost Robotics.
  • Coordinated Robotics with a self-funded team using drones.

According to Timothy Ghung, Competition Manager at the DARPA Tactical Technology Office, the design of the Subterranean Challenge is motivated by first responder communities. “We are inspired by the need to conduct search and rescue missions in a variety of underground environments, whether in response to an incident in a highly populated area, a natural disaster or for mine rescue,” he said.

First race: third place to privately funded CTU-CRAS
First race: third place to privately funded CTU-CRAS

He added that DARPA will judge the performance of the systems over the entirety of the competition, constructed to test the robotic systems in varying conditions. The SubT Challenge represented a man-made tunnel environment.

The robot race moves next to an urban underground environment in February, and to natural cave settings in August. Late entries are still possible. The last event is in August 2021 and on that occasion DARPA plans to test the robots with combinations of the previous three settings – mine, urban and cave.

While self-funded teams can chase a share of up to $200,000 in prize money in each leg of the physical SubT competition, the overall winner can claim the $2 million grand prize. There are separate cash prizes in the virtual competitions.


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