Omni Casters!?!?

[usbcd36]

<R06> ROBOTs must use ROVER WHEELS (as supplied in the 2009 Kit Of Parts and/or their
equivalent as provided by the supplying vendor) to provide traction between the ROBOT and
the ARENA. Any number of ROVER WHEELS may be used. The ROVER WHEELS must
be used in a “normal” orientation (i.e. with the tread of the wheel in contact with the ground,
with the axis of rotation parallel to the ground and penetrating the wheel hub). No other
forms of traction devices (wheels, tracks, legs, or other devices intended to provide traction)
are permitted. The surface tread of the ROVER WHEELS may not be modified except
through normal wear-and-tear. Specifically, the addition of cleats, studs, carved treads,
alterations to the wheel profile, high-traction surface treatments, adhesive coatings, abrasive
materials, and/or other attachments are prohibited. The intent of this rule is that the ROVER
WHEELS be used in as close to their “out of the box” condition as possible, to provide the
intended low-friction dynamic performance during the game

Basically, the only thing allowed to touch the ground are rover wheels.

Edit: They say the only things allowed to provide traction are rover wheels, but they say nothing about normal force. It does raise one issue: there must be no friction between the omni wheels and the ground, something impossible to do in reality.