how does crab drive work?

[Soukup]

Hi,

Next year I will probably have the opportunity to move on to another team other then my own (I'm graduating). It is highly possible that I'll be starting a rookie team. Anyways, with my limited knowledge on robot drive systems, other then our own team (we had a 2-speed shift on the fly system), I would like to build a crab drive robot which would probably happen over the summer.

What I'd like to know, is from any teams, that have succesfully made a crab drive system, how does it work. If you use omni wheels, to get a strafing ability I'd also like to know how that works. I've been looking at Wildstang's site, and have gather basic blueprints of their system, but what would really like to know is:

what kind of motors are used on each wheel?
how are they geared?
how are they configured?
What motors are used to turn the wheels (either 1 motor for 2 wheels, or 1 motor for 1 wheel)?
If you gear the motors up or down, what size sprockets are used?
Anything special that we show know about your system (angled gears, strength of the chains, speed, power, weight, unique programming)?
and most importantly, what kind of control sytem is used (what does each joystick do)?
Basically any information you can provide about a crab drive system would be awesome.

If possible, it be awesome to have some pictures, but whatever you can come up with I'd really appreciate. Thank you very much.