Mechanum Wheel Sizes

[Steven Donow]

Originally Posted by nxtsoccer

Allright, from what I read (assuming we chose mecanum), we should plan on using a semi-flexible frame that allows for the wheels to raise/lower a little based on terrain, should do most of our prototyping work during the off-season, and use 6" mecanum wheels (AM 6" HD?). Any other suggestions or things I forgot?

So, I suppose all that remains is to figure out how to turn these wheels. Any suggestions for the drive train? We currently only have the frame kit included with the 2012 Rookie KOP, which means 2 CIMs, chain, 4 sprockets, and two CIMple boxes. Would purchasing two more CIMple boxes with accompanying CIMs to use with the existing lengths of chain and sprockets work, or will we need to purchase entirely new drive train parts to make the robot move? (The rookie kit came with four jaguars, so we do have enough motor controllers for the four necessary motors.)

And thanks to everyone for all of these awesome suggestions!

EDIT: And plenty of practice to go with the new axis of travel!

One thing you're missing is that for mecanum, you need to power each motor seperately, so 2 CIMple boxes won't work. I've seen teams use both these:
http://www.andymark.com/product-p/am-0688.htm
http://www.andymark.com/product-p/am-0482.htm

The 2nd one probably fits your idea of having a flexible frame for going over terrain.

[nxtsoccer]

Originally Posted by stevend1994

One thing you're missing is that for mecanum, you need to power each motor seperately, so 2 CIMple boxes won't work.

I know , that's why I was wondering in the next sentence if we should go with two more CIMple boxes, or scrap the two we have for entirely new drive train parts (hopefully keeping the CIMs).

[Nemo]

Originally Posted by nxtsoccer

I know , that's why I was wondering in the next sentence if we should go with two more CIMple boxes, or scrap the two we have for entirely new drive train parts (hopefully keeping the CIMs).

There is nothing wrong with using the CIMple boxes to save a few bucks. The kit sprocket reduction (26:12) plus the CIMple box gives about a 10:1 gear ratio, which is a nice ratio for 6" mecanum wheels. If we're starting from a 2012 kit of parts, that move saves about $180 as compared to using Toughbox Nano and AndyMark hubs to direct drive. If you want to use the same equipment on a competition robot next year, though, I think the extra $180 is a good move. The Nano boxes have the following advantages over CIMple boxes: takes up less space, no chains to mess with (easier to build + more reliable), Nano is a nice box that runs really smoothly and is probably more efficient than CIMple + chain.

Having said all of this, and everything in my previous post... honestly, I agree with the people who suggest doing a kitbot on steroids (a nice 6WD robot) instead. It sucks when you can't climb an incline very well and other robots can shove you around at will.