Technologies for Officiating in Sports

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There are several embedded-system technologies that have emerged over the last two decades, to improve or automate refereeing.

The Grant-Hicks tennis-court line-monitoring apparatus was one of the earliest electronic line-judge systems that aimed to provide automated line-calls in tennis matches. The system was built out of pressure sensors underneath a court surface, where the sensors were sensitive enough to detect the impact of a ball, and differentiate it from the impact of a player’s footfall. The Grant-Hicks system could make automated “in” and “out” calls relative to the boundary lines of a tennis court. In addition, the system could detect foot-faults through the use of directional microphones along with a timing circuit to detect the activation of the baseline “in” sensor prior to, or the during the time of, the player striking the ball. Using a piezoelectric sensor on the net, the system could also make automated net-cord legal-serve decisions. The Grant-Hicks system was perhaps an early IoT system—a fascinating combination of embedded pressure sensors in the court, a piezoelectric sensor at the net, and sound sensors for localization—put together to improve refereeing. While the system was used in the 1974 Men’s World Championship Tennis match in Dallas and in the 1975 Ladies’ Virginia Slims tour in Los Angeles, it was never commercialized. David Lyle also independently developed an electronic officiating system based on a combination of an electrically conductive tennis ball, a micro-computer network system for making and using automatic line-call decisions in tennis, along with an impact-detection apparatus for determining whether or not a tennis ball landed in or out of the court. The Lyle system was also never commercialized.

000831_cir_TENNIS_CLR_chCyclops was the first commercial electronic officiating system, introduced in the 1980s, and invented by Bill Carlton (an aeronautics engineer and the inventor of the plastic shuttlecock used in badminton). Known as the “magic eye” service-line machine, Cyclops consisted of a pair of transmitter and receiver boxes that were bolted into the sidelines of the tennis court, on either side of the net. The Cyclops transmitter box sent 5-6 infra-red beams, 1 cm over the ground, over to its counterpart receiver box on the other side of the net. The system was designed so that one infrared beam ran along the good side of the service-box line, while the other four infra-red beams ran on the fault side. When a ball is hit on/inside the service-line, the ball momentarily broke the first beam and turned off the 4 others. If the serve was long, it would break one of the 4 other beams instead, which produced a loud audible beep. The receiver unit was attached to a control box in the hands of the service-line umpire, who activated the box before a serve and deactivated it after the serve. Cyclops sometimes produced phantom beeps if the control button was pressed at the wrong moment. John McEnroe reportedly commented on Cyclops to an umpire, “I don’t want to sound paranoid, but that machine knows who I am.” In another famous incident, Ilie Nastase reportedly got down on his knees to speak to Cyclops about an “out” call during Wimbledon 1980.

Trinity was an electronic net-cord monitor that was so named because it aimed to help the three parties–the umpire, the players, and the person who sits at the net and might get hurt. It was introduced to reduce the high risk (due to serves as fast as 137mph) to a human who would otherwise need to manually monitor the net. Trinity was comprised of sensors that were placed at each end of the net and a cable that was fitted to an umpire-operated hand control. The umpire would press a button when the serving player tossed the ball and would release it after the ball crossed the net. A beep sounded if the ball touched the net cord.  Trinity was developed by the Brauer brothers, and piloted at ATP matches in 1995.

Hawk-Eye is a real-time ball-tracking system that was developed by Dr. Paul Hawkins as a technology to enhance the TV broadcast of cricket matches in 2001. It has since evolved into a tool that is now being used for officiating in a range of sports, including tennis, soccer, cricket, hurling, baseball, snooker and Australian rules football. Hawk-Eye relies on a system of 6-7 high-performance cameras placed high above and around the field-of-play, with the cameras tracking the players and the ball. The video data from the cameras is processed by the computers, and is used to synthesize a 3D representation of the ball trajectory, which is accurate to within 5 mm. The processing is also able to take into account player skid and the compression of the ball.

Goal-line technology for soccer has been a field of innovation in the past few years. Several contending technologies have emerged, ranging from Adidas’ Intelligent Ball with Cairos’ Goal-Line Technology system to the Hawk-Eye system.

8512_141207113128The goal of the Cairos system is a smart soccer-ball with sensors and a miniature RF transmitter (suspended ingeniously to be able to ensure that it withstands the forces of the ball being kicked, while nevertheless providing accurate data), along with sensors and a miniature RF transmitter in the shin-guards of players, and possibly the umpires, on the soccer pitch. The data from these miniature transmitters is received by a central base-station that, along with a central computer, provides a real-time, in-game data-aggregation and movement-analysis system for soccer. The system claims to provide data to within millimeter accuracy of position/location tracking 200+ times a second. The purpose of the system is to provide movement analysis, flight-path tracking of the ball, etc., in order to assist with refereeing, coaching and training. Because every player is tracked, it is also possible for the system to assist in analyzing combinations of players and plays.

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