New instant replay technology looks to end controversies

By Andrew Lippe

A new instant replay technology developed by Mitsubishi Electric
Research Laboratories in Cambridge, MA, could put an end to the use of
cameras and monitors and, instead, use photo-sensor tags to
electronically track bats, balls, rackets, and even players.
“Tracking is a huge problem in the sports industry, says Ramesh
Raskar, MERL senior research scientist. “High-speed cameras are far to
expensive and not as efficient at motion capturing. Our product is high
speed, and because, it is a projector and not a camera, it is available
at an extremely low cost.”

The first application of the just-developed technology is air hockey.
Why air hockey? Ramesh Raskar, MERL senior research scientist, says the
high-speeds the puck travels at, and the constantly changing angles and
locations, made it the perfect control subject. It is tracked at 500 times per second without using a high speed camera.

Each prototype tag includes embedded electronics and circuit boards
that are in the puck. Tags include a TSOP-7000 infrared receiver
module, Flash memory, photosensors and even an optional radio. LED
devices (which MERL calls projectors) the size of a candy bar are then
used to track the photosensors. The data pulled in from the LED
projectors can then be sent to an unlimited number of receivers that
decode the location of the object. In the air hockey demo, for example,
up to 10,000 movement patterns are tracked by two projectors,both are
above the table, close to each other, 1 for x coordinate and 1 for y
coordinate, one on
each side of the table.

“It is very easy to read the data, says Raskar. “While the puck is
moving the player can see what is directly happening to the puck.”

MERL’s objective is eventually get the sensors small enough to be built
into other sports equipment and even uniforms. Multiple projectors
would then be placed around the field of play.

“In the future players could wear it,” says Raskar, a move that would
eliminate controversial calls like whether a football crossed the goal
line or whether a hockey goal was scored while a player was in the

It can also track touches. “If you wanted to know if it was a handball
or not, the tags would be able to tell you if his fingers ever touched
the ball,” Raskar says.

Unlike most cameras, everything LumiNetra uses is off the shelf. The
tags uses very inexpensive parts such as IR-decoding modules and
micro-controllers and that is why Raskar believes the technology will
be a big hit with professional and amateur teams and leagues.

In fact, Raskar says some leagues have already shown interest and will
be shown a prototype at the Siggraph convention in Boston later this
week. The system is low cost and uses the same elements as your TV
remote control in your home,” he says.

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