Babolat Tennis Racket’s Sensors Measure Swing Speed, Strength

Before Julia Görges stepped onto the court at the French Open on May 26, the German tennis pro did something strange. She stopped to turn on her racket.

Görges, ranked 107th in the world in women’s singles, was the first player to use the newest product from tennis’s oldest manufacturer: the Play Pure Drive, a digitally enhanced racket created by the French company Babolat. With each strike of the ball, tiny sensors in Görges’s racket recorded the strength of the impact and the spin. An accompanying smartphone app processed the data and also calculated the number of forehands, backhands, serves, and overhead smashes. Görges, who’s sponsored by Babolat, won her first match and lost the second. She hoped her new gadget could help figure out why. “Sometimes you are in the emotions … and you sometimes lose the vision [to see] things,” she said in a postgame interview.

In the nearly century and a half since modern tennis was invented, rackets have gone from wood frames to metal to composites, and from natural gut strings to synthetics. “We’ve had in tennis some evolution, but no revolution in the technology for quite a long time,” says Pierre Mace, 36, the Babolat engineer who invented the new racket. The Play Pure Drive, which costs $399, was rolled out in the U.S. in December. In January it was approved by the International Tennis Federation, with one restriction—coaches aren’t allowed to use the data during the match, only after.

Mace oversaw the development of the Play in Lyon, in a converted warehouse behind the Babolat headquarters. The company has been in the tennis business since 1875, two years before the first Wimbledon championship, when a British businessman came to the city—then known for its slaughterhouses—looking for a manufacturer to turn animal innards into tennis strings. Babolat expanded from guts into synthetic strings in the 1950s, into rackets in the 1990s, and recently into shoes and apparel. Last year it took in €147 million ($200 million), and it has been trading places with Wilson as the No. 1 racket maker in the world in terms of revenue.

The technology in the Play fits in a cigarette-lighter-size package inside the handle, the bulk of which is dedicated to the battery. An array of electromechanical sensors detect the way the racket is moving, twisting, or turning. Another set analyzes the racket’s vibrations. “Tennis is a combat sport, so you always want to know how you’re doing compared to the guy in front of you,” says Eric Babolat, the fifth generation of Babolats to head the company.

“The first thing I saw [when I introduced the racket] with the kids is that their concentration went up,” says Adriana Serra Zanetti, 38, once a top-ranked tennis player who now works as a private coach. “Because they know that everything is being recorded.” For adult players, the app offers a series of levels that can be unlocked through regular play, or lost if the racket is left to sit for too long. A dedicated social media network allows users to compare their stats—power, technique, and endurance are combined into a single number called the pulse—with people around the world, including some pros.

The biggest challenge in designing the racket, says Mace, was ensuring that the added electronics didn’t alter its weight or balance. Another was developing the algorithms that turn the sensor data into useful information. For that, Mace brought in 200 tennis players of various skill levels to a half-size tennis court in the company’s warehouses. The participants’ movements were then recorded by a high-speed camera, and the ball was tracked with radar.

The results surprised Mace and his team of engineers. The best players delivered the most power not when the ball hit the center of the racket, as has long been tennis gospel, but when it struck slightly higher up the face. “The really good players had learned this instinctively, through years of trial and error,” says Mace. “But with our data we were able to see it.” The Play will mainly be marketed to recreational players, but Görges, who learned she hit 57 percent of her shots at Roland Garros on the top part of her racket, will continue data-mining her game. “It’s about putting the pieces of the puzzle together,” she says.

6 June 2014 | 1:00 am – Source:

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