[Pat Roche]

One solution that hasn't been mentioned yet is using six wheel drive without the drop wheel and a reduced friction wheel on the outsides. We used this setup this past year and it worked out quite well (that combined with inset corner wheels) after some practice. For the "scrub wheels" we used IFI's with worn out rough top flipped over so the backing was contacting the floor. I found this to be ultimately superior to omni wheels for two reasons. The first is that if you are tipped forward or back they offer more traction that an omni wheel does. The second is while turning it adds just enough scrub to slow the turning down to a reasonable speed (reducing the "squirrellyness"). It does however reduce your overall pushing force per wheel due to your weight force being divided over 6 wheels vs. 4 and also due to the lower friction on the corner wheels. That said, we deemed that trade-off acceptable for the maneuverability and over power loss of the system.