Can Cristiano Ronaldo Score on Mark Rober’s Robotic Goalkeeper?

I’m an American and have therefore never watched a soccer match before. But I hear that Cristiano Ronaldo is pretty decent at the game. The question is if he’s good enough to score on Mark Rober’s robotic goalkeeper.

Even as someone who has never watched soccer, I do know two things about the game: the goalkeeper’s job is to keep balls from going into the goal and that goal is humongous. So it stands to reason that the goalkeeper must move around a lot, anticipating opposing players’ tactics and ball trajectories to cover the entire goal. That isn’t an easy thing to achieve with a robot and so Rober had a challenge ahead of him.

Rober’s first step was tracking the ball’s position in space and using that information to calculate its trajectory. To do that, he used OptiTrack’s PrimeX 120 camera system, which puts 12 500fps cameras around the field (though that was eventually upgraded to 22 cameras). Those look for retroreflective stickers on the soccer ball to determine its position. With as few as three positions, it is then possible to calculate ballistic trajectory—though spin and other factors can still cause funny things to happen that are much harder to predict.

Since Rober had a good idea of where the ball would enter the goal, he then needed a way to block it from doing so.

To do that, he put what is essentially a life size cardboard cutout of himself on rails running the length of the goal. There really isn’t anything too complicated there. It just takes motors and cables. But it moves fast enough to reach the right position in just a small fraction of a second.

Was that enough to successfully and reliably stop Ronaldo from scoring? No, no it wasn’t. As it turns out, Ronaldo has so many fans because the guy is, like, really good at soccer. He noticed that the robot leaves a small gap on the side of the net, because it doesn’t move far enough over. Ronaldo was able to use his superhuman soccer abilities to thread the ball through that gap, scoring on the robotic goalkeeper.

Even so, the robot is still good enough to go up against mere mortals.