Wheel Positioning

Technical Technical Discussion
1

We had a slight surprise when we got our chassis put together. We have 2 high traction 8" wheels, 2 (relatively) low traction 8" wheels, and 2 8" omni-wheels. Our original plan was to put the high-traction wheels in the rear, with the low-traction wheels in the middles and the omni wheels at the front; however the high traction wheels are a slightly taller 8" than the low traction, thanks to the thicker treads on them.

So, we’ve got a bit of a split on one to do with the wheels, the prevailing opinion on the team is to put the high traction wheels in the middle and the low traction wheels in the middle, but we’re not all convinced, so we decided to ask CD for opinions on the optimal wheel config.

Our front end consists of a ball collector, and we will be shooting from the back (catapult like design), and the argument for the high traction wheels in the middle is to allow the robot to tip in either direction (one with good turning capabilities, and one with higher traction), however some team members are concerned about not having all 4 of the traction wheels on the ground at all times (and being easily spun out).

Thoughts?

2

I’d put the high traction wheels in the center and use the same wheels for both sets of outer wheels.

Your robot will pivot on whichever wheels have the most traction.

3

High traction in the center. If you’re not using all traction wheels, then you’ll ALWAYS* want your traction wheels in the center.

*Not always always, but most of the time always

4

normally i would say center $@#$@#$@# well. but not so sure this year.

friction wheels might be very neccisary for going onto the ramp. and if they are in center they may lose contact with the ground when mounting the ramp; omnis might not giving you enough traction to get on the ramp (well).

5

I see two things that should work well for you:

  1. High traction wheels in the center. Other wheels on the outside. Using the “medium” traction wheels on the outsides will give you more traction.
  2. Use high traction wheels for the center, and either the front or the back. Then, use the omni’s or these “medium” traction wheels for the other set. This should make you a “rocker” drive train, but with one balanced, level potion instead of two “rocked” or “tipped” positions like a normal rocker drive train.

Best of luck
-Jeff

6

Thanks for the feedback everyone. We ended up adding a second set of high-traction wheels in place of the medium traction wheels, and leaving the omnis in place (which don’t have any drive power). I was a bit suprised to see us turning so nicely with all that traction, but it seems like we’re going to stick with this setup (plus it took more than 2 hours two change out the wheels, so nobody really wants to experiment anymore :smiley: )