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Unread 10-12-2003, 01:35
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@JohnVNeun
AKA: John Vielkind-Neun
FRC #0148 (Robowranglers)
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Re: Coaxial crab stalling

Quote:
Originally Posted by Tytus Gerrish
coaxial crab...
Im woried about backdriving the globes and throwing my stteing out because my Drive motors wont be transmiting torque thru the wheels when theyre jammed, it will be into the module witch is rotated by the Globe
Tytus,
You should always design your "low gear" so it has enough torque to slip your wheels (no stall!) This means, you don't have to worry about stalling motors/modules when you're "fighting".

In high gear... don't get into pushing matches. Especially not for extended periods of time. Experiment with your wheel traction, see what you can get away with. This will greatly depend on how many motors each of your coax gearboxes use, and what ratio they are running at.

Make sure the coax-swerve steering/programming are such that you don't end up having wheels out of allignment. (there is nothing worse than watching a swerve with 3 wheels going 1 direction, and the 4th going somewhere else.)

Also... try to protect your gearboxes/wheels from objects getting inserted and jamming them up. (add shields, etc).

Another way to deal with this would be to just gear your swerving motors (globes) down enough so they can easily handle a little extra "bleed off" torque from the semi-stalled, slipping wheels.


John

PS - Finding good ratios for your drive is the most important thing. You want to find a good balance for high, and low. (or are you trying for a CVT?) There are piles of threads discussing this design process. For the application you're talking about (with 2 motors per side: drill & chip or similar power outputs) I'd recommend probably ~2-3 fps low gear, and ~11-12 fps high gear (max).

Remember, it is always better to err on the "slow" side. Especially with a swerve drive. (for reference, Wildstang was ~6-7fps and even that seemed fast!)
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