[Al Skierkiewicz]

Matt, thanks for the better picture. I am sure I have one some where but that was the best I had at work.
Construction... The large wheels consist of a sandwich of 2 aluminum pieces in which areas are relieved to hold a small axle for the white rollers to turn on. The rollers had slots cut in them for the o rings and then the o rings were glued in place. Each drive module had two assemblies because we found that the rollers were not in contact with the floor long enough to grab. Two assemblies next to each other but offset, allowed at least one roller to be in contact with the floor at all times. The rear drive set used normal wheels and performed the drive for steering. Note that a normal tank style drive with this arrangement allowed responsive steering without the side friction problems.
This robot was for the ramp competition and the drive was strong enough that we were able to drive around with another robot on our back and drive across the ramp.
We have discussed various designs to replace the roller/o-ring arrangement but have not used this design again. A roller made from aluminum with some kind of tooth cut in the surface would be ideal though.
I should mention that our mechanical engineer, Raul, is the one who is responsible for this design. It was in direct response to the electrical team's research on high current demands in tank drive systems.
Just a few more hours...