To clarify....
We need wheel location and don't care about robot location.
Our challenge is ....we are using omni wheels and the middle strafing wheel does get enough traction to push our robot sideways. Our experiment is to put a 8" rubber traction wheel in the middle and remove the tread between every other spoke (the wheel would have ~4" of tread then 4" of no tread). We would use the traction wheel to move sideways, but then need to "park" the wheel in the nearest location that doesn't have tread. (We understand the "parking" action will potentially alter our robot location by up to 2" when we need to "park" the wheel.) Determining the wheel location on the drive axle would be ideal for our application. This would allow us to rotate the wheel to the nearest "park zone" when needed. We would start the wheel in the same location every time when powering up the robot. (unless there is a better idea for identifying "home" on our sensor design)
We are using
this wheel
Hope this helps.
Pulling this all together is a real stretch for our young team but will be a GREAT learning experience. We have a student that is really inspired to pull this all together and this will be a great knowledge to have on our team.