Like many great ideas, Puttr came about because of some enforced downtime during lockdown. Entrepreneur and founder of several successful start-ups Matthew Allard had been on the golf team at university, and lockdown had him contemplating an at-home putting game that he and his son could both enjoy. Matthew had a personal interest in how software and computers can interact with the real world, and having taken post-graduate courses in embedded systems was keen to make use of what he’d learned.
One thing Matthew knew already was that “putting practice is boring and lonely” (don’t they have crazy golf courses in the US?) yet it accounts for 42% of time golfers put in. Creating a means to connect fellow golfers and ‘gamify’ putting could transform this rote activity and allow members of the golfing community to challenge each other with online tournaments.
Hits and misses
Matthew originally aimed to track made and missed putts via an app using sensors in the hole of an at-home putting mat hooked up to GPIO pins. However, he soon discovered this approach was limited: “I could detect when a ball went in the hole, [but] I couldn’t detect missed putts.” Next, Matthew tried break-beam IR sensors to get more precision and measure missed putts, as well as ‘makes’, but “quickly realised that any sun exposure would cause false positives in the break-beam”.
A friend tipped him off about Raspberry Pi, and Matthew soon saw he could use computer vision and a wide-angle lens to detect the location of the physical hole, then track any golf ball that passed its field of view. Once a ball has entered or exited, it sends the full ball path data over Bluetooth to a connected app on an iOS or Android device, he explains. Details of each putt are logged, with the user able to access stats on their performance and optionally share it with other Puttr users.
Raspberry Pi quickly proved a great choice, since it offered an operating system with all the tools he needed for the software along with good value hardware that worked well together. “Many suppliers tried to talk me into creating my own board [but] there were many reasons to use Raspberry Pi.” The camera connection, Bluetooth, Wi-Fi, and processor were all included. Matthew was also encouraged by the strong community keen to help with any troubleshooting he might need, given this was his first ever Raspberry Pi project.
Embrace the light
At first, Matthew stuck with his infrared break-beam idea, testing it in his garage in the evenings after long days at his day job. There were “a ton of tweaks” to get the computer vision to work well under different lighting conditions. Eventually, it seemed as though the beams were working just as he expected. “I would get a break when the ball enters the ramp, and another one when and if it entered the hole. Perfect!”
Replicating results when demonstrating the embryonic Puttr game to his son was less successful. In fact, it didn’t work at all in daylight. Matthew eventually realised that sunlight hitting the beam’s receiver was preventing the circuit being broken even when a ball passed through it because it emits infrared rays of its own: “Apparently I missed that in school!” Connecting Raspberry Pi 4 to a GATT server (for Apple devices) as a headless Bluetooth peripheral meant code pairing was not an option. Instead, Matthew created a Bluetooth Write Characteristic that can receive a Wi-Fi SSID and password specifically for the task. He then wrote all the computer vision code and app software to make Puttr work.
Prototyping involved laser-cutting Baltic birchwood, and Matthew’s first foray into 3D design and printing using CraftCloud to create the box used as both ball tracker and holdall, the ramp, and ball return chute. The clever design is portable, with the mat rolling up inside.
Matthew praises the “stable, tested OS, camera interface, Bluetooth and Wi-Fi, and says choosing Raspberry Pi meant R&D took at least a year less than choosing a different setup with costs that would have been much higher. New versions and applications are already planned. Since launching 18 months ago (after a successful Indigogo crowdfunder), the Puttr app has logged more than a million putts. The clever take on pitch and putt now has worldwide league tables, games and challenges, with a subscription model for golfers keen to pit their skills against others.
