[lbarger]

Four wheel drive, skid steer, robots take a lot of power to turn, especially if it uses high traction wheels. The advantage of 6 wheels is that the corner wheels bare less of the weight, making it easier to turn. Most 6 wheel configurations use either lower friction wheels on the corner or the center wheels are slightly lower than the corner wheels (1/16 - 1/8") to carry a larger portion of the weight. The 'wobble' from the lower wheel is almost unnoticed on carpet.

The disadvantage of 6 wheel robots this year is they must match the 45 degree incline of the bump to go over it (if you choose to do so). A long wheel base 4 wheel robot can cross the bump with less total tilt. You do have to watch you total ground clearance as you can high center if it the frame is too low.