DARPA SubT Final: How It Works and How to Watch

The preliminary rounds of the DARPA Subterranean Challenge Finals are kicking off today. It's been a little bit since the last DARPA SubT event-the Urban Circuit squeaked through right before the pandemic hit back in February of 2020, and the in-person Cave Circuit originally scheduled for later that year was canceled.

So if it's been a while since you've thought about SubT, this article will provide a very brief refresher, and we'll also go through different ways in which you can follow along with the action over the course of the week.

The overall idea of the DARPA Subterranean Challenge is to get teams of robots doing useful stuff in challenging underground environments. "Useful stuff" means finding important objects or stranded humans, and "challenging underground environments" includes human-made tunnel systems, the urban underground (basements, subways, etc), as well as natural caves. And "teams of robots" can include robots that drive, crawl, fly, walk, or anything in between.

Over the past few years, teams of virtual and physical robots have competed in separate DARPA-designed courses representing each of those three underground domains. The Tunnel Event took place in an old coal mine, the Urban Event took place in an unfinished nuclear reactor complex, and the Cave Event-well, that got canceled because of COVID, but lots of teams found natural caves to practice in anyway.

So far, we've learned that underground environments are super hard for robots. Communications are a huge problem, and robots have to rely heavily on autonomy and teamwork rather than having humans tell them what to do, although we've also seen all kinds of clever solutions to this problem. Mobility is tough, but legged robots have been surprisingly useful, and despite the exceptionally unfriendly environment, drones are playing a role in the challenge as well. Each team brings a different approach to the Subterranean Challenge, and every point scored represents progress towards robots that can actually be helpful in underground environments when we need them to be.

The final Subterranean Challenge event, happening this week includes both a Virtual Track for teams competing with virtual robots, and a Systems Track for teams competing with physical robots. Let's take a look at how the final competition will work, and then the best ways to watch what's happening.

How It Works

If you've been following along with the previous circuits (Tunnel and Urban), the overall structure of the Final will be somewhat familiar, but there are some important differences to keep in mind. First, rather than being a specific kind of underground environment, the final course will incorporate elements from all three environments as well as some dynamic obstacles that could include things like closing doors or falling rocks. Only DARPA knows what the course looks like, and it will be reconfigured every day.

Each of the Systems Track teams will have one 30-minute run on the course on Tuesday and another on Wednesday. 30 minutes is half the amount of time that teams have had in previous competitions. A Team's preliminary round score will be the sum of the scores of the two runs, but every team will get to compete in the final on Thursday no matter what their score is: the preliminary score only serves to set the team order, with higher scoring teams competing later in the final event.

The final scoring run for all teams happens on Thursday. There will be one single 60 minute run for each team, which is a departure from previous events: if a team's robots misbehave on Thursday, that's just too bad, because there is no second chance. A team's score on the Thursday run is what will decide who wins the Final event; no matter how well a team did in previous events or in the preliminary runs this week, the Thursday run is the only one that counts for the prize money.

Scoring works the same as in previous events. There will be artifacts placed throughout the course, made up of 10 different artifact types, like cell phones and fire extinguishers. Robots must identify the specific artifact type and transmit its location back to the starting area, and if that location is correct within 5 meters, a point is scored. Teams have a limited number of scoring attempts, though: there will be a total of 40 artifacts on the course for the prize round, but only 45 scoring attempts are allowed. And if a robot locates an artifact but doesn't manage to transmit that location back to base, it doesn't get that point.

The winning team is the one with the most artifacts located in the shortest amount of time (time matters only in the event of a tie). The Virtual Track winners will take home $750k, while the top System Track team wins $2 million, with $1 million for second and $500k for third.

If that's not enough of a background video for you, DARPA has helpfully provided this hour long video intro.

How to Watch

Watching the final event is sadly not as easy as it has been for previous events. Rather than publicly live streaming raw video feeds from cameras hidden inside the course, DARPA will instead record everything themselves and then produce edited and commentated video recaps that will post to YouTube the following day. So, Tuesday's preliminary round content will be posted on Wednesday, the Wednesday prelims post Thursday, and the Final event on Thursday will be broadcast on Friday as the teams themselves watch. Here's the schedule:

The SubT Summit on Friday afternoon consists of roundtable discussions from both the Virtual Track teams and System Track teams; those will be from 2:30 to 3:30 and 4:00 to 5:00 respectively, with a half hour break in the middle. All of these streams are pre-scheduled on the DARPA YouTube channel. DARPA will also be posting daily blogs and sharing photos here.

After the Thursday Final, it might be possible for us to figure out a likely winner based on artifact counts. But the idea is that even though the Friday broadcast is one day behind the competition, both we and the teams will be finding out what happened (and who won) at the same time-that's what will happen on the Friday livestream.

Saturday, incidentally, has been set aside for teams to mess around on the course if they want to. This won't be recorded or broadcast at all, but I'll be there for a bit to see what happens.

If you're specifically looking for a way to follow along in real time, I'm sorry to say that there isn't one. There will be real-time course feeds in the press room, but press is not allowed to share any of the things that we see. So if you're looking for details that are as close to live as possible, I'd recommend checking out Twitter, because many teams and team members are live Tweeting comments and pictures and stuff, and the easiest way to find that is by searching for the #SubTChallenge hashtag.

Lastly, if you've got specific things that you'd like to see or questions for DARPA or for any of the teams, ping me on Twitter @BotJunkie and I'll happily see what I can do.