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#46
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Re: Mecanum wheels
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Put another way, if the ball is a mere 6" off target, you'd rather have the ball bounce off you (and then have to go chase it) than see a robot with the ability to take a half step to the right? ![]() |
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#47
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Re: Mecanum wheels
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My point is that the ball will never be anywhere close to 6" from being caught, it will be much farther away and completely un-catchable because a mecanum robot can not hold field position. If your catching robot uses mecanum wheels, pushing it out of the way will be a common and effective defensive strategy. In a game like this where field position is everything, a mecanum robot is at an extreme disadvantage. The only role I can see a mecanum robot playing effectively is a robot that cycles the ball by itself with no assists. As soon as it tries to play a role where it has to stop and wait for its alliance to do something it would lose its field position and ability to add assist points. |
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#48
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Re: Mecanum wheels
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#49
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Re: Mecanum wheels
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Having a robot that can be pushed in any way is disadvantageous to being a good target for catching, so I'd say the best pure catcher is a robot without wheels. However, making the trade-off of allowing some pushing in exchange for the ability to move and complete other tasks could be a successful strategy. Toggling between a drivetrain and a traction device would give the "best of both worlds" at the expense of complexity (independent swerve being another solution, albeit even more complex). |
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#50
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Re: Mecanum wheels
Designing to be defended against is a really good way to put a ton of work that may or may not see a benefit in competition.
Remember 2006, when 25 had a robot that was solely human fed, and basically shot from the floor? And went undefeated right up through division elimination rounds? Ultimately the benefit of mecanum ends up coming down to what your game strategy is. If it's to be a flexible assist bot, it may very well be worth it-- if it's being a thrower bot, it very well may not be. Ultimately it's all just speculation until we get to competition regardless. Just like any other year, there will be successful 6WD robots and successful mecanum robots. The team makes the tools it uses worthwhile, not the other way around. |
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#51
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Re: Mecanum wheels
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#52
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Re: Mecanum wheels
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We're very happy with how that design turned out, and are confident in the durability, especially in a game with a flat field like Aerial Assist. If you jump a robot off a loading dock, will the wheels crack? Yes: Based on our testing... not until the 3rd jump. ![]() If you slam the wheels into a wall with a rolling robot, will they crack? Not in our testing. I'm confident that VEXpro Mecanum Wheels will stand-up to normal wear and tear during an FRC season. If a wheel breaks, it is likely that the wheel wasn't damaged due to extended match play, but instead the robot was dropped when being loaded into a mini-van. Also, I hope it goes without saying for VEX products at this point: If you have a problem or break, please contact our tech support folks so they can help make it right. prosupport@vex.com I'm especially excited to see teams using our new 4" Mecanum Wheels. This game lends itself perfectly to small wheels, and I believe there are some strategies which would benefit from holonomic motion. -John |
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#53
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Re: Mecanum wheels
Is there any information on mecanums wheels and drivetrains? Live Axle vs Dead Axle?
I have never use them and am looking for information. Transmission? Does and one have some good information to share. Thanks |
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#54
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Re: Mecanum wheels
Where have you been looking?
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#55
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Re: Mecanum wheels
Sure, there's lots of info. See that search link at the top of this page? Click it, enter "mecanum", and you'll find lots.
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#56
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Re: Mecanum wheels
Apologies to JesseK and bEdhEd. I was not attempting to say either of you said there was power loss for mecanum moving forward/backward. I was not trying to counter what either of you said, but using your correct statements as an example of the types that are very commonly misinterpreted.
my post was attempting to be pro-active about a future reader's misinterpretation, and was instead itself misinterpreted. I think there is a word for that (other than failure). I guess we can agree that I clearly didn't say it very well. |
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#57
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Re: Mecanum wheels
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As for your apology, team bEdhEd graciously accepts! |
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#58
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Re: Mecanum wheels
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#59
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Re: Mecanum wheels
So Mecanum vs 6WD and all things being equal I understand most of the pros and cons.
But if you look at the Robot in 3 Days team Boom Done they have 8 motors on their drivetrain - 4 cim and 4 minicim. What if instead of having a straight gear reduction, a team were to use a direct drive shifting transmission such as the Vex Pro ball shifter on each Mecanum wheel with a Cim and Mini-Cim as the input to each wheel? And you took that against a 6WD drivetrain with the three CIM Vex Pro Shifting transmission per side? Does that muddy the water a bit? |
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#60
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Re: Mecanum wheels
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Do the math and you'll have your answer. This stuff is pretty cut and dry. |
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