The curling broom was definitely one of the hardest projects I've ever worked on. The electronics are pretty trivial, but my fabrication skills just weren't up to the challenge - serious curlers can apply a crazy amount of force to the head of a broom when they're playing.
My first curling hack was to attach a speedometer to a tiny RC monster truck wheel and mount both on the end of the broom. When playing as a sweeper, I would slide along and touch the wheel to the ice as the thrower released the rock to get an accurate speed reading of the rock. Especially during draw weight shots where you're trying to hit the button, this aided the call as to whether to sweep or not. The idea may have been good, but the nuances of curling and the fact the ice is constantly changing speed throughout the game made the data not very useful. In the end, a well trained 'eye' was just as accurate and much quicker to make the call.
>This has the interesting effect of decreasing the friction between the stone and the ice, causing it to both decelerate and rotate more slowly
Decreasing friction decreases speed ? What is this sorcery ?
Read it as "both decelerate more slowly and rotate more slowly" and it's an accurate description of what happens when you sweep in front of a curling stone.