RALEIGH — Science has now answered a question that has bedeviled football fans, coaches, the defense and sometimes even the offense several times a game for the entire history of the sport: Wheres the ball?
Not that it was simple. It took a rocket scientist, an N.C. State University expert on magnetic waves and even the people who brought you Goofy.
Researchers at NCSU, Carnegie Mellon University and Disney (which not coincidentally owns ESPN) announced Friday that they have developed a new visual tracking system that can allow television viewers and referees to determine precisely where a football is or has been on the field, even when the pigskin is buried beneath a mountain of hefty linemen or crosses the goal line hidden in a scrum and then is pushed back.
The system uses magnetic sensors around the field and a tiny transmitter inside the ball to track its location in three dimensions, on and above the field. That location is shown on television with a visual cue reminiscent of the visible-only-on-TV first-down line that has been used by broadcasters for several years. In one video now online of the Carnegie Mellon football team using the system, a circle around the ball follows it around the field trailed by a visual streamer.
The lead author of a new paper describing the system is Darmindra Arumugam, a former doctoral student at Carnegie Mellon now at NASAs Jet Propulsion Laboratory. David Ricketts, an associate professor of electrical and computer engineering at NCSU, was another author. He helped figure out how to measure the magnetic fields to determine the balls position, and also helped develop the transmitter inside the ball.
The research paper, Three-Dimensional Position and Orientation Measurements using Magnetoquasistatic Fields and Complex Image Theory, appeared online in that well-known sporting journal IEEE Antennas and Propagation Magazine.
The transmitter, Ricketts said, is so light well under an ounce that footballs with it can still fall under the maximum allowed weight.
We even had a quarterback test it by throwing spirals, and it performed well, he said.
And if thats all not enough to shock traditionalists, the football is rechargeable. Wirelessly.
For now, the system is accurate to less than a foot while the ball is on the ground and about 2 feet when it goes airborne, though there is no theoretical limit to the accuracy, so it should be possible to improve it, Ricketts said. A basic goal is to get accuracy to within half a football length, the estimated margin of error for referees using eyesight to figure out the placement of a ball.
The results arent just academic. The research was performed with funding from Disney Research, which was acting on interest from inside ESPN, Ricketts said. Its now up to Disney and presumably ESPN to decide whether to invest in efforts to perfect the system.
We basically demonstrated the feasibility and accuracy; now the next step would be a strong engineering effort, he said.