New Technology Can Detect a Football’s Exact Position on the Field

Researchers from North Carolina State and Carnegie Mellon University, in collaboration with Disney Research, have developed a tracking system using low magnetic fields that can track a football in 3-D space.

Officiating in football, especially in the National Football League (NFL), has already been revolutionized thanks to slow motion instant replay and the ability to review challenged plays on the field. This new technology would eliminate a coach's need to challenge a play where a disputed call over the spot and placement of the football is in question.

The "Localization with Magnetoquasistatic Fields and Complex Image Theory" project sought to determine the position and orientation of a light-weight, low-frequency transmitter using quasistatic magnetic fields in situations where one's line of sight is disrupted by other objects - in this case, the eyes of a football official during a goal-line play or a crucial first down call where it's hard to get good positioning to make the proper judgment.

The researchers placed a small transmitter into a football. This transmitter - within the standard deviation of accepted professional football weights - induces a quasistatic magnetic field sensed by receiver stations around the football field. These antennas can receive signals from the transmitter and track its location.

"With at least five unique measurements of the magnetic field, the three-dimensional (3D) position and orientation of the ball can be determined using complex image theory to account for ground effects," the Disney Research report noted. "This system has several advantages including immunity to multipath propagation, unaffected by line-of-sight occlusions caused by groups of people, and minimum complexity on the person/object to be tracked."

The researchers tested a prototype of the ball at a collegiate football practice, which you can view in this Disney Research report. It's hopeful that this technology will be useful in pile-ups and other situations where a referee's view is obscured, but the researchers are still fine-tuning the system to get the precision down to half the length of the football.

The study was published in the IEEE Xplore Digital Library on May 29. Dr. Darmindra Arumugam is the lead author and a former PhD student at Carnegie Mellon University and now works at NASA's Jet Propulsion Laboratory.