[DonRotolo]

That was my first thought too, that those wheels on infield grass will prove challenging. As will picking the bits of grass from the wheels. It will perform FAR better if you can get to do it on infield dirt.

I think the hardest problem is detecting drift from center. Once you set the 4 wheel speeds such that the robot moves as desired, you can just leave it exactly like that for the 10 revolutions. But the imperfect surface will cause drift - grass quite a bit, dirt not so much - and detecting (and correcting for) that is a huge challenge.

Perhaps an unpowered omni wheel mounted parallel to 'normal forward' at the back of the bot. If the bot moves exactly circularly, the small wheels on the omni will turn, but the big wheel won't rotate. When the bot moves towards or away from center, the big wheel will move, and you can detect and compensate for that. (Like the sensor wheels some teams used in Lunacy)