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Originally Posted by Oblarg
And yeah, the rollers turn while rotating, but it's not as if someone hitting you from the side will cause you to start spinning.
I've had to push against 4wd and 6wd drive robots with mecanum before, and not once have I seen the rollers spin - try it yourself, you'll notice that the difference is not nearly as big as most people make it out to be. Yes, there's a lower cap before mecanum wheels start skidding, but how often have you seen wheels skid in a FIRST pushing match? It's not exactly a common occurrence - in my time in FIRST I really can't recall ever seeing our mecanum wheels skidding on the carpet. In my experience, the idea that "mecanum drive gets pushed around a lot" is almost entirely a myth.
People put way too much store in "If we end up exactly head to head and are pushing each other, my robot will win out." That's not a realistic situation. In the context of an actual competition, in which your goal is not to push head to head with other robots, mecanum is not at a significant disadvantage in terms of being pushed. Take into account the fact that defense isn't allowed to push you while you're scoring, and the best way to get into the scoring zone will probably be dodging the defensive robot rather than pushing it (in fact, are you even allowed to push another alliance's robot into your scoring zone?), .
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2006 Boston Regional Finals Matches 1 and 2 come immediatly to mind for me. Every thing you say you have never seen occur happens in those matches and the drive train on the defensive bot was not that good, it was a poorly executed 4wd design.
I have seen Mecanum drives pushed directly backwards by a 4 or 6 wheel drive despite trying to push forwards. There is definitely a disadvantage to mecanums whenever there is pushing.
Quote:
Originally Posted by Oblarg
and I really don't see what the benefit of a 6wd is.
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I think the advantage to 6wd is pretty obvious and pretty much common knowledge, it is simple, reliable and easy to manuever. There is a reason that the majority of teams on Einstein every year seem to be 6 or 8wd