Quote:
Originally Posted by Shane 2429
the 6 wheel drop drive is also commonly refereed to as west coast drive or wcd
|
6 wheel drive dropped center is exactly what it says, 6 wheels, drop the middle on each side.
A 6 wheel drive can be a West Coast Drive, but WCD is more specific; it is typically classified by live axles, cantilevered wheels, dropped center on a 6 wheel (or 2 center wheels dropped on an 8). Of course there is no strict definition, but if you look at a 254 bot, you'll be able to see a little more clearly.
Here's pic, it's 968's practice chassis from what feels like eons ago
http://www.chiefdelphi.com/media/photos/31597
Now to the topic of the thread. The theory of a dropped center 6 wheel drive is that only 4 wheels touch the ground at a time. That should decrease the frictional drag, since you're effectively cutting the wheel base in half on a given turn. Shorter wheel base means shorter lever arm for the frictional force opposing your slip turn, and thus an easier turn. The problem with an omni wheel in the middle is that you're omni wheels are linearly aligned with your axis of rotation, so a push to the middle could cause you're robot to lose control. Omni wheel are made to decrease/(ideally all but eliminate) kinetic friction of the sliding wheel. If in fact your center of rotation is about your two center wheel, there shouldn't (ideally) be any kinetic friction in the sideways direction, so your ability to turn will be the same omni wheel or with a traction wheel. The problem is, now with omni wheel, when you're being pushed, you want that friction for stability, but you no longer have it. I endorse switching the omni wheel out for a traction wheel.