Jul 012012

I am writing this during Wimbledon fortnight, which is appropriate as this is all about assessing the power of tennis racquets in a way that is quantifiable and repeatable. The International Tennis Federation is the ultimate body regulating the sport. It operates the three major team competitions, the Davis Cup, Fed Cup and Hopman Cup and sanctions the four Grand Slam competitions – the Australian, French, Wimbledon and US Open. As such it needs to be able to assess objectively the performance of courts, balls and racquets to be used in International competitions and ensure that they conform to given standards. As a by-product, it also provides a comparative performance measure to the manufacturers of racquets and balls.

I was asked to look at the system that they currently used to measure the power of racquets. This is defined as being the speed at which the ball leaves the racquet. Relatively early in the growth of sports engineering the ITF worked with a PHD team from Sheffield University to create a power measure for tennis racquets. The original system was now ten or more years old and was becoming unreliable. Stripped to the basics the system comprises a shaft spinning the racquet at a given ‘service’ speed striking a ball that falls from a hopper at a known speed to meet the racquet head at a range of points precise to +/- 3mm. The speed of the ball is measured as it passes a series of electronic eyes.

The task is essentially an upgrade, updating a sound technique with today’s controllers, encoders and drives linked to provide reliable and predictable results and ensure that the ITF can be confident in the integrity of the data it publishes.

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