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Unread 09-01-2013, 14:13
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Re: Mecanum vs Treads

Quote:
Originally Posted by Kevin Sevcik View Post
See that drawing of that bump around the entire pyramid? That bump means mecanums are going to hate driving near the pyramids.
Kevin is wrong! The mechanums are innanimate objects so they are not capable of hating. It will be the pit crew who have to fix the mechanums after the drivers bump into the lip around the pyramids who will be doing the hating.

At Alamo last year, we learned that we had to check that all the rollers on all four mechanums were turning freely after each and every match. If a roller was binding, we removed it and bent the aluminum spider back out. Bumping into the edge of the bridge (lowered) was just one way to bend the aluminum spiders. Just a few (2-3) binding rollers caused the robot to deviate from the expected path in unpredictable ways. We could see the driving performance degrade throughout a match. I am sure this messes up your force vector diagrams.

We also found that the rollers on our mechanums would bind when new because the urethane had coated the inside of the brass bushings. It took a lot of work to disassemble them and clean them out so that they would spin freely.

www.youtube.com/watch?v=1mrNH0Czq0Il