Coefficient of Friction Testing

[JamesCH95]

The more I read up on various stories the more I believe that most FRC wheel act like car tires. It matters what temperature they're at and what contact pressure they see. Therefore it is important to test the drivetrain as a whole unit, not just individual wheels. I

f some wheels in the setup are more heavily weighted than others they will have a lower CoF than identical wheels loaded less, i.e. a drop-center 6wd, where the center two wheels generally bear 90%+ of the robot's weight. In a configuration like this I believe that it would be most efficient to use wide wheels in the middle and narrower wheels on the outside corners.

Additionally, if one were doing testing, it would be interesting to heat up the wheels by spinning them for a few moments, then re-trying the static friction test.

@DonRotolo- your slippage value of 12% is very similar to high performance traction control systems in race cars; IIRC typically 8-10% slippage resulted in maximum straight-line acceleration. This may be because the surface of the wheel/tire is getting 'ripped up' a little bit, causing it to engage the driving surface positively, but I am no tribologist.