4 wheel drive vs. 2 wheel drive

[eNyoron]

Between rear and front wheel drive, it's really not viable to use a rear wheel drive unless you don't plan on ever exchanging an empty cell... or being pushed into a corner. That portion is carpeted and if you use rear wheel drive to get there, you're going to end up with the front wheels on the carpet with high traction and the powered wheels on the regalith with low traction, making it incredibly difficult to move. And backing into the corner wouldn't work either, there's a trailer in the way.

[smartkid]

Where your weight goes is up to you but please know that any and every wheel touching the ground needs to be powered! Also know that your bot should weigh 119.99999 lbs (without battery and bumpers).

[IKE]

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.

[camper365]

8-wheel drive
Use pairs of wheels

[AdamHeard]

Kind of late, but thought it was worth posting.

Our final configuration uses 48 wheels.

[Molten]

Originally Posted by AdamHeard

Kind of late, but thought it was worth posting.

Our final configuration uses 48 wheels.

I want to see that. Got a picture?

[AdamHeard]

Originally Posted by Molten

I want to see that. Got a picture?

... Three days until LA.

[Molten]

Originally Posted by AdamHeard

... Three days until LA.

I won't be able to watch. Please post a pic or a vid after the fact. Ok?