Limitless Potentiometers

[JesseK]

There are a couple of different ways to approach rotation sensing, and one you might not have thought about is a light sensor combined with a state machine. A couple of pictures of this are in the 2006 FIRST design book.

Take a light sensor that's not mounted on the rotation and have it reflect off a plate that is mounted on the rotation (or vice versa). Where you want the rotation to stop, mark it with a black sharpie. It's literally that simple, but at the same time it's not as robust as other sensing methods.

Another way to do this, if you're trying to measure drive train ticks, is to put a mark parallel to the axle shaft on a shiny part of one of your rotational pieces. This will give you only one interrupt per rotation. If you want it to be more accurate, put 2 marks to give you 2 interrupts per rotation.

The other thing you could do is ask for pictures of how others mounted their potentiometers. We only had 1 pot on our bot in 2007, but it never broke. It was mounted to the inside of 1/4 the length of a hinge, so the hinge bolt itself took most of the load.