Creating an electromagnetic football

Football is an American tradition, sometimes full of camaraderie, team loyalty, and nail biting referee decisions. But what if the refs could use electromagnetic waves to help pinpoint exactly where the ball landed to make their game calls?


Football is an American tradition, sometimes full of camaraderie, team loyalty, and nail-biting referee decisions.

But what if the refs could use electromagnetic waves to help pinpoint exactly where the ball landed to make their game calls?

We go inside the lab to learn more.

[ Cheers and applause ]

Football fans know that tracking a football isn't easy.

The game is fast.

The players are big.

Coaches and even referees know that, too.

The trouble is, inches matter in football.

The exact location of the football can determine whether a player gained enough yardage for a third-down conversion.

The exact location can also show if the ball crossed the goal line for a touchdown.

In short, the spot of the ball can affect who wins the game.

Just watch what happens in this Appalachian State football game.

Can you tell if the ball crosses the goal line?

Now, engineers at NC State may have a way to know for sure.

What we do is we turn the football into a small electromagnet.

The scientists work with Carnegie Mellon University and Disney Research to create a way to track a football in three-dimensional space.

You can do -- you can do left, right; forward, back; up, down is three.

And then the football can be rotated this way, and the football can be rotated this way.

So he could actually track the football in any orientation around.

It's all done using a low-frequency transmitter that is integrated into the football.

This is the rechargeable battery for the device.

And then here's the actual transmitter.

This is the on-off switch, so they can turn it off.

These are the two wires from the antenna coming up into the transmitter.

And here's the key -- the transmitter creates a current in the wire, which turns the ball into a pretty simple electromagnet.

This time-lapse video shows how it's all put together.

The ball is deflated and unlaced.

The bladder is removed.

And then a wire is wrapped around the bladder several times.

The bladder is put back into the football.

And then the antenna and the transmitter are epoxied together to make them more durable.

Everything is then packed back into the football, which is laced back up and then reinflated.

The weight is within the standard deviation of accepted professional football weights.

The ball is carefully balanced.

If you think about a science experiment you might have done in school where you wrapped a coiled wire and then connected the coil of wire to a battery and then looked at what happened to a compass, you're measuring the same sorts of things that you did with the iron filings and the permanent magnet.

In one case, it's a permanent magnet.

The other case, it's created by the currents.

But the fields are very similar.

And effectively, what we're doing is we're taking the football and turning it into a magnet, just like the coiled wire that you did in the science experiment in school.

And here's how it works.

Watch the player, and then watch the arrow on the side of the screen.

You know, everybody likes to do something cool.

Everybody likes to see something that's entertaining.

So you can see, as he's running down here, the ball really is changing directions as he moves it in his arm and runs across the field.

So you can see not only his location but also that orientation.

And you see, there's a red and a yellow line.

And the yellow line's really telling you the orientation.

So when the ball's flat, horizontal to the field, the yellow line's straight.

And as it tips up, that yellow line gets shorter and shorter and shorter.

There's a series of antennas placed around the field to track the signal produced by the transmitter.

A computer uses the data to place the ball.

This is one just showing the accuracy.

So we've got one of our researchers walking the line.

And this is showing the direction of the ball, so it's pointed to his right.

And he's within one foot of the goal line, mostly within 6 inches, as he walks.

And remember, the football is producing a low-frequency signal.

That's important because low-frequency signals pass through the human body.

The ball won't get lost in a pile-up of players.

We use magnetic waves, which may not mean anything to most people.

But typical radio waves get absorbed by our bodies or get shoulder pads, helmets, metal things.

The magnetic waves tend to ignore us.

We're sort of transparent, if you will, to the magnetic waves.

So by using magnetic waves, when all the players huddle around the ball, the waves just propagate through them.

And we can see them just fine.

So the players themselves don't affect the fields we measure whatsoever.

And the electromagnetic signals produced are good for tracking a football and safe for people.

There actually is an analysis that we had done where you actually calculate... You take a human body model, and we calculated the football sitting right here, if you held it, how long you could hold it.

And I think you could hold it for a full 4 or 8 hours, and you'd still be below all the acceptable limits.

Researchers admit the system needs fine-tuning.

But the NFL and several other sports leagues are reviewing the technology.

And it was just -- it was just cool to be able to do something that enabled us to interact with a sports team.

And that was so easy to understand.

You know, a lot of the work we do in research doesn't always take us into something that's exciting and also that you can share.