4wd turning

[Woolly]

Originally Posted by Dylan Danzeiser

I've read a bunch about how the wheelbase has to be longer than the track width for a 4wd to effectively turn, assuming a relatively equal lateral and inline coefficient of friction. However, these talked about turning in place, not turning while moving forwards, so I was wondering if there would be much of a difference.

I think you've got the inverse relationship there regarding wheelbase vs. track width there. Otherwise, turning while moving forwards or backwards while be similarly more difficult than other drive trains, but not as difficult as turning with a 4WD at a stop. Usually, this means that a 4WD will need room to swing around to pull a 180, which is a pain for the driver to plan for out on the field, and makes defense against said 4WD much easier.
Also, this means that designs that force the driver to regularly re-orient the robot, like team 1986's 2013 and 2014 robots, absolutely requires a drive train that is easy to rotate. Preferably, it should be able to rotate without the turn profile being too much larger than the robot itself, as the center of rotation should be as close to the center of the robot as possible.