[Clem1640]

We've done some static friction coefficient testing on both carpet and polycarbonate surfaces and found that the HiGrip wheels are excellent. We, however, did not test Colsons (even though we used them last year) or Versa wheels (yet - we have purchased a set for testing).

We test on two axes: the in-drive direction and perpendicular to this.

I agree that friction coefficient (between the wheel and driven surface) and the normal force applied between these two surfaces (generally the robot weight) are the key factors in determining traction.