Quote:
Originally Posted by AllenGregoryIV
This looks really great I have a couple questions
1. Why did you choose to pivot the traction wheels down instead of moving the mecanum wheels?
2. What are the final gear ratios to each set of wheels?
3. Why did you choose to build under the kit frame instead of on top of it?What's the sub-frame made out of?
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We pivot the traction wheels down for a few reasons. First, by putting them nearer to the center of the machine, it makes turning with four high-traction wheels a bit easier to accomplish. We also gear down further to that wheel set, so it makes sense for it to be at the end of the gear train.
The gear ratios are 8.45:1 at the mecanum wheels -- that's one of the options for the Toughbox Nano -- and about 25:1 at the traction wheels. The traction wheel ratio makes things pretty slow, but it's easy to swap in sprockets to speed things up as required.
The kit frame is 1.25" thick and the output of Toughbox is 1.5" from its edge, so when using a 6" mecanum wheel, we'd end up with just .25" of ground clearance if we built things the other way around.
The subframe, right now, is 1x1x.125" angle bolted to the perimeter of a .125" perforated PVC sheet and hung from the Toughbox Nano housings. It is intended to hold electronics and would need to be enhanced if it were going to see more substantial loading.
Quote:
Originally Posted by Ether
What mecanum wheels are you using, why did you select them, and what (if any) issues have you had with them?
What makes your mecanum implementation better?
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This is based on AndyMark 6" mecanum wheels --
http://www.andymark.com/product-p/am-0136.htm
We used this last season and I'm happy with the build quality and performance. They're heavy, but they're not as heavy as the 8" set we originally played with years ago and we're willing to deal with the weight and cost in place of building our own.
Our mecanum implementation worked. I didn't program it, so I can't speak too much to what made it work, but our programming team did a fantastic job there. We had accurate, fast, field-oriented drive that allowed us to fully use the movement capabilities of the mecanum wheel set. In my experience, most teams fail to achieve the level of control we managed.