Electronic installation in the grunting racquet handle

Installation of the grunting racquet electronics. Photograph by Seiya Kobayashi

Late one afternoon browsing the net for new projects, I experienced two parts of my life collide: electronics and tennis. That’s because prior to my job at Make: as a technical editor, I was a tennis pro. During those years on the court, it was quite common to chide people who would grunt when their racquet made contact with the ball. So when I discovered Seiya Kobayashi’s Grunting Tennis Racquet, a playful take on the grunting problem — I could barely contain myself.

For those that might not have played the sport before, it’s quite common to hear tennis players grunting during tense games where the score is close. But don’t be fooled, making noise when the racquet impacts the ball is totally unnecessary. Some players use these outbursts as a way to distract their opponents, and some coaches even teach this as a form of fair play. For most, grunting in tennis is simply bothersome.

Well, Kobayashi has a wonderful solution for this problem, he made a racquet that does the grunting for you. Gone are the days of a sore throats and damaged vocal cords. Now you can focus on hitting the ball in desired location and let an Arduino, accelerometer, and speaker worry about timing the obnoxious guttural sounds. This spectacular combination of fun and function has kept me laughing ever since I found Kobayashi’s site.

The Hardware

The components of the project should be quite familiar to readers. Kobayashi took an Arduino Pro Mini and combined it with an accelerometer, Adafruit audio FX shield, speaker, and a LiPo battery with a power button. He used both Arduino and Processing sketches along the way to prototype his design idea, determining what project concepts worked and what did not. All the while, the biggest challenge was to fit all of the components into the the hollow handle of a tennis racquet, which he mostly accomplished. A careful eye will spot the speaker protruding quite a bit from the racquet frame, but this only adds to the in-your-face project attitude.

Using an Arduino Pro Mini helped Kobayashi deploy the circuit in such a small space as a racquet handle, but so too did the already small dimensions of the accelerometer breakout board and his custom perfboard layout. For those unfamiliar with the Pro Mini, it’s a tiny version of an Arduino UNO without the FTDI integrate circuit that handles serial-to-USB communication. This means you can’t just wire up a USB cable between your Arduino Mini Pro and computer. Instead, you’ll need either an FTDI Friend or FTDI cable to interface between the two devices.

gruntingracquet

Prototyping circuit design to fit inside the racquet handle. Photography by Seiya Kobayashi

One of the most interesting aspects of Kobayashi’s project is his iterative documentation. Each prototype has a short blurb or video updating the design changes and feature improvements. Not only is this great reading for others, it’s also a great way to remind yourself the history of a project. It’s a difficult discipline to establish, but documenting each major design goal of a project enables for much more robust project documentation.

Currently the project only allows for Maria Sharapova mode — named after the Russian female tennis star who is known for her on-court vocalizations — though the code is written in such a way to easily add additional grunters. For my version of the build, I’m thinking about using either Rafael Nadal on-court sounds or maybe just record my own.