The ball comes to rest outside a wide open goal. Keeper and defenders are nowhere to be seen. The attacking player races towards it, as fast as their little legs can carry them. They pause, bring their head up, and swing a leg back to shoot. They extend a foot, miss the ball completely and fall with a thud on the turf.
This happens a lot. This is robot soccer.
This week, until Sunday, more than 170 teams from universities and research laboratories in more than 30 countries in Sydney to compete in RoboCup 2019. With them are the robots they have been refining for more than a year, here to compete in different competitions including soccer, search and rescue and home assistance.
Robot soccer has a number of leagues. There’s one for small and speedy Roomba-like robots, another for Dalek-esque robots which are fitted with a paddle for punting the ball, the ‘standard platform’ league in which all teams use a Nao humanoid robot from SoftBank, and three ‘humanoid’ leagues for bots of different sizes that can move around on two legs.
On the opening days of the event at the International Convention Centre, there is a lot of falling over and other unforced errors, as the teams tweak their code and mechanics.
“That’s surprisingly hard to do, to get them to get up!” explains UNSW Professor Claude Sammut, chair of the events organising committee, as a soccer-playing fallen Nao does the splits and draws their legs round them to stand.
The standard platform league – the ‘SPL’ – is chiefly about software; optimising the Nao’s movements and giving them autonomy, computer vision, a game plan and the ability to communicate with teammates.
“The on board system is not much more powerful than your phone, so coding efficiently is a big challenge,” Sammut adds.
At the end of each SPL competition, teams share their code for the benefit of the sport. Teams often take the best elements of the robots that reach the finals, but must also add something of their own to enter.
“At the end of each meet, all teams release their code so we can all analyse what the best teams have done in attempt to create robots with winning strategies,” says Kenji Brameld, team leader of UNSW’s rUNSWift SPL team.
“This is why the competition is more and more challenging every year,” he adds.
UNSW’s Naos had a particularly good walk in 2015 (when they took the world title for the fifth time) which is now being used by most other teams. It’s tough to have to give away a competitive advantage, rUNSWift haven’t won since, but it’s for the good of robotics.
“We don’t want it to be just a competition, it’s about pushing the science and technology,” Sammut says.
At a small size league game, where the robots must be no wider than a plate and less than 15cm tall, the 12 robots on the pitch are deadlocked and quivering on the spot.
“Sometimes you get a game stuck!” says Sammut.
The emphasis of this league is coordination and control. Teams are given feeds from multiple overhead cameras that they process on off-field computers which direct the bots over radio.
Soon the robots are running again, whizzing across the green carpet, moving into space and marking their opponents.
In an ‘adult humanoid’ game, the robots are far slower and less steady. Teams of two compete, with the robots shadowed at every step by a human to catch them if they fall. Which they do often.
Although many have refined kicking without tumbling, a slight nudge from an opponent can send months of work crashing to the ground.
“With the smaller robots, these are super-fast and super-accurate. They can pick out a pass and all those things. With the legged robots it’s more complicated to control and more about the engineering. Motors are good at turning wheels they’re not good at moving legs. So we have to focus more on the control,” Summat explains.
Real world challenges
Having started on a small scale in 1997 in Japan, RoboCup now features a number of non-soccer competitions.
One of them, the RoboCup@Home category, is the largest international competition for autonomous service robots. In various leagues, the robots – which include the Softbank Pepper robot and custom built models – have to navigate a mock four room apartment, introduce themselves and remember human habitants, and find and fetch various items without bumping into things.
There’s also an industrial category in which robots have to carry objects, navigate and cooperate in a factory line setting, and a concurrent junior competition with a number of categories including soccer and escaping a maze.
In the ‘RoboCupRescue’ competition, custom built robots have to complete a number of tasks in a disaster scenario. After being tested across difficult terrain from rubble to slippery stairways, the robots have to locate items, unscrew caps, search for simulated victims and pick up objects.
“The thing that killed the robots in Fukushima was the debris on staircases. We’re emulating that here. The challenges are stylised but they capture the problems faced in real disaster situations,” Summat explains.
Some of the tasks this year were devised by the NSW Police Force’s Rescue and Bomb Disposal Unit, and the competition is adjudicated by the U.S. National Institute of Standards and Technology (NIST) using their test for response robots.
Robocup participants learn much from competing, and each year understanding of software and mechatronic engineering advances.
“It enhances their hands-on learning experiences and greatly increases their employability. They get to work with some of the leading researchers in AI and robotics as well as developing practical skills,” Sammut says.
The biggest lesson however, is probably that of Murphy’s Law, says Sammut, as a Nao soccer-bot stands up and immediately falls, over and over again.
“Absolutely you prepare, prepare, prepare, then you go to the competition and something unexpected happens. You have to learn how to cope with things going wrong!” he says.
RoboCup 2019 is open to the public until Sunday, July 7.