Tennis Sensor App Showing Flat for Spin – Video Analysis

Backhand slice and topspin. Neither are flat.In an article in July, we argued against sensors showing flat as a reading for spin. Zepp, Qlipp and Babolat Play all have three spin types within their apps – topspin, slice and flat. Sony Smart Sensor has two- just slice and topspin.

Biggest Problem with Flat

On the screenshot (right) from our recent 100 ball accuracy test, you can see that a backhand has been played. The ball has left the racket and is in roughly the same place following impact. Yet the racket is in a very different position. The above image is a topspin backhand and the bottom is a slice backhand. Two very different shots.

Despite this, the Qlipp sensor’s output (shown in the video) was the same for both ie a flat backhand. Sony on the other hand, showed one as slice and one as topspin. This problem distorts all the data from a player’s hit session.

And it’s not an isolated problem. We didn’t have to look too far to find the anomalies displayed on the video. 50 out of 100 shots in the sensor test were shown as flat. In our experience, the numbers are similar with Babolat Play and Zepp.

Video Analysis

The video below shows why it’s a problem. Two forehands and two backhands are highlighted. It’s obvious to the tennis playing viewer which ones are slice and which ones have been hit with topspin.

When you have a look at the output from the app, however, all shots were displayed as flat.

Solution to the Flat Problem?

Simple. Get rid of it. Show varying degrees of topspin and slice the way the Sony Smart Sensor does. Actually, the Qlipp sensor does make an attempt at the degree to which the ball has been hit with spin. Far too often, however, it defaults to flat which tells the player nothing. Worse than that, it’s distorting the data for a shot, a session and over time.



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