6WD vs 8WD

[IKE]

Originally Posted by Triple B

From my experience, the 8 gives you more stability at higher speeds and better predictability of how the robot will handle. We also decreased the diameter of the outside wheels instead of offseting the axle height.
mike d

Did you change the ratios to match teh diameter changes, or just allow for the inherent scrub to occur?

[Triple B]

no change of ratio, just let it ride.

[Alan Anderson]

Originally Posted by IKE

Did you change the ratios to match teh diameter changes, or just allow for the inherent scrub to occur?

Our 2007 "Rack 'n' Roll" robot was a six-wheel drive with no center drop. It had extra-thick tread on the center wheels and it drove like a dream. We never figured out whether the very slight discrepancy in wheel circumference made any difference one way or the other. There was some conjecture that a teeny bit of scrub on the corner wheels might actually result in better turning.

[Blake L]

Personally, I like 8WD, although my opinion might be a bit biased because I haven't driven a 6WD robot anywhere near as much as I've driven an 8 wheeled one.

This year my team used eight 4" diameter wheels geared 7:1 and I loved it.
Here is a video of us playing with the chassis a week into build season:
http://www.youtube.com/watch?v=inI40uMKuEE

If I remember correctly, the center two wheels are dropped 1/16". We later added another two motors to the drive train which gave us a nice balance of speed and power.