6WD Pros and Cons

[Kevin Sevcik]

Originally Posted by Daniel_LaFleur

To me, this sounded like if he just added 2 more powered wheels would it be better. The answer to this is just adding 2 more of the same type of wheels, at the same level, without changing wheelbase will not assist in turning nor will it (in and of itself) give you more traction.

Daniel,

You're correct that adding 2 more wheels at the same level won't help traction, but it will help with turning. It won't help as much as a pair of lowered wheels to shorten the wheelbase, but assuming equal weight distribution on all six wheels, then each wheel has 33% less weight on it than a 4wd configuration and will be 33% easier to scrub sideways. Assuming the robot turns about the midpoint of your two center wheels, you still have only 4 wheels scrubbing but now with 33% less weight. So the robot is theoretically at least 33% easier to turn. That's not counting gains in the torque the middle wheels put out since they're operating under static friction instead of dynamic friction. So adding 2 more wheels certainly does help turning a little.

I'll admit the above all happens in the land of point masses and spherical chickens, but I don't think reality is THAT far off in this case.