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View Poll Results: Rear wheel drive vs. Front wheel drive vs. All wheel drive
All wheel drive 110 88.71%
Rear wheel drive 7 5.65%
Front wheel drive 7 5.65%
Voters: 124. You may not vote on this poll

 
 
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Unread 06-01-2009, 07:49
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Re: 4 wheel drive vs. 2 wheel drive

My recommendation would be to run some tests with the kit chassis. We subbed some wheels out on a 4x4 chassis last night and ran it on the FRP and carpet. We did a long wheel-base and a short wheel base. We also shifted the CG from 50/50 to almost all on the rear or the nose. All of these are without the trailer so far, so we will try those tonight.

All I can say is I would recommend doing a few tests for yourselves. The dynamics are very different on the carpet vs. on the FRP. Set-ups that were nice and controllable on the FRP wouldn't turn if two side wheels got on the carpet, and set-ups that were easy to turn off the carpet were very squirelly on the FRP. Also, the bot lateral grip seemed a lot lower than the inline grip.

That brings up a very important point, there is a hierarchy when you design:

Ideas are great, but can often be flawed.
Fully thought out theories are better, but often involve a lot of assumptions.
Models (calculations and 3D models) are often made of some tests and measurements and some assuptions.
Test based data is even better yet especially if it validates your model assumptions.
Prototypes can be even more accurate.

My point on this is I have read through a lot of threads on how these bots should be built and how they will behave. I have a lot of vehicle dynamics experience, and I was still surprised by a couple of our tests last night.
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