Everyone must have noticed the increasing use of technological aids in sport, from the videos being used to "second guess" referees and other officials (to the extent that cricket now uses a "third umpire" in major matches) to the touch sensors used in fencing. In the judo world, in order to protect referees reputations for fairness and sound instant decision, it has been decided after considerable research, to introduce technological assistance in determining the validity and scoring level of throws.
The system developed is formed of three components - a passive sensor system to be laid under the competition area, and active sensors worn by the two competitors, which transmit via a loop pick-up to the discriminator and display situated on the mat control table. Although the passive sensors are and essential part of the system, acting to discriminate between body and mat contact, the more exiting innovations are in the active sensors fixed to the competitors shoulder blades and upper buttocks, and the impact sensor fixed to the centre of the back. (Note - the sensor harness for female is somewhat more complex due to the difference in shape). The contact sensors indicate the orientation of the player's body on the mat - i.e. whether they are flat on their back or on one side etc. - and the impact sensor measures the impact force landing from a throw.
The wiring for the sensors gave us many problems. We had to develop plastic wiring based on carbon fibres to avoid instant diqualification for the competitors wearing metal articles. The batteries are silver oxide based on plastic pouches - which are normally leak free - and are carried in a special pocket in the rear skirt of the jacket. The LED indicator, which flashes when the system is operating, is worn at the end of the belt in view of both referee and opponent. The activation switch goes just inside the left lapel of the jacket (or right lapel for left handed players).
Correct use of the equipment involves some new techniques by both competitor and referee. The competitor, in order to avoid spurious signals, must remember to de-activate the system by switching off the control switch immediately on going into ground work, or immediately prior to attempting a sacrificial technique such as tomeonage. Obviously, they must re-activate it on resuming their feet. The referee must learn to read the digital display on the discriminator - in two parts, showing "flatness" and impact (we are considering calibrating the system to avoid this problem and will require volunteer tori, uke, and IJF referees for the several thousand throws needed for the calibration exercise.
For safety reasons, referees and first aid personnel should wear rubber socks when on the mat, so that they do not form a circuit if touching one or both contestants. In addition, the referee and corner judges will need to assume responsibility for the safety of the system on the mat. We have found the sparks and arcing from the back of the jacket indicate a serious malfunction and if the plastic wiring over heats it is likely to result in smoke from the jacket. In such an event some scorching or charring of the white tee-shirts or leotards worn by female competitors mar result. So far we have found no need for fire extinguishers to be kept at the control table, but we are recommending that in the future all competitors' clothing should be made from flame retardant material. It should be noted that in the event of electrical storms, all competitors should immediately lie down - preferably facing north so that the wiring harness is aligned with the earths magnetic field - and de-activate the device.
The major problem appears to be signal interference. Obviously, in view of the nature of the signal transmission and reception system, all the wearers of hearing aids must be banned from the competition area. Mobile phones should be impounded at the door. Anyone found in possession of a television remote control will be subject to official disciplinary action, as these devices have been found to overload the active impact sensors, resulting in feedback to the competitors nervous system, causing involuntary contraction of the back and leg muscles - the competitor "throws" themselves.
We have already tackled the problem of power failure for the mat sensor system and display, and have developed a back-up power supply operated by the table staff pedalling an auxiliary generator. Indeed, it has been suggested that this should form the primary source in view of concerns expressed by medical advisors over the general fitness levels of table staff in their sedentary occupation.
We are hoping to exhibit the system at the British Youth Closed Championships to be held in the Western Area in March 2000. Our IJF representatives will then be in a position to implement international recognition in time for the Olympic Games. The additional entry fee for competitors and spectators covering the cost of equipment will be determined closer to the date. We will keep you informed through the news letter of the progress of this exiting new British innovation.
Angelsa Williams and
John Lucas
Joint Project Directors
I.D.I.o.T.
(Ippon Discriminator Impact of Throws)