Quote:
Originally Posted by Squeakypig
I love the drive train you guys came up with. I have never been a fan of mechanum drives but the fact that you paired it up with some tread wheels should make it pretty effective.
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The traction wheels are geared very low as well. (I'll be cagey about just how low, but lets just say we want to be able to power through any defense that gets thrown at us!)
However, please don't give us credit for the octocanum drive idea -- we stole it quite shamelessly from 488. Mind you, there are some important differences (gear ratio, wheel placement, pod shape), so we made it our own, but the credit for the original idea goes to them.
Also -- as for not loving mecanum wheels: they're expensive, quirky, and require tight control of your robot's CG. They also allow your robot to be controlled exactly like a first person shooter with almost no modification to the programming. Their primary flaw -- the lack of pushing power -- is truly a significant and non-trivial drawback, and anyone who says otherwise certainly hasn't had our experience with them (and this will be our fourth year using them). In many game applications I would not recommend them, but in some I would. Octocanum removes this drawback but adds in weight management and battery management issues, as well as sheer expense -- we would not have been able to afford it this year without the very generous donation from Gates.
Quote:
Originally Posted by Squeakypig
I know team 217 and 148 had Nanodrive back in 2010 which is essentially the same concept, just be careful on your weight. I know those teams had to remove their hanging arm because their drivetrain was too heavy.
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That's a great heads-up for anyone looking to implement an octocanum drive. The drive train system (including pneumatics, compressor, electronics, frame, etc.) is just under 80 lbs -- the heaviest we've ever had by a great deal! Our projected robot weight without protective coating stuff (lexan, etc) is 108 lbs with all systems (bridge manipulator, ball intake, conveyor, and shooter) -- this gives us a little wiggle room for a few more sensors or brackets or whatnot, and will allow us to add weight (steel blocks) to get to 120 lbs in a strategic manner to ensure that our CG is dead-center and below the frame.
If you have any other questions, I'd be happy to answer them!