Finding Mecanum Wheels

[JesseK]

Originally Posted by mathman05

I don't see why you would be worried about getting your mecanums stuck on the ramp. I understand the metal of the wheels would be touching the ramp, but you shouldn't be going up the ramp sideways in the first place.

I believe he means strafing while on the ramp, not strafing in order to climb up the ramp. In any case, any sort of drive train will have issues climbing the bump at an off angle unless there's a suspension system. At an off angle it's guaranteed that at least 1 wheel will come off of the ground. If you want to go mecanum and climb the ramp, you will have tradeoffs to consider regardless of how you design it.

Those mecanums are pretty cool; actually in hindsight 4 sets of those little mecanums would have been perfect for our drive train since I'm sure they can handle 20lbs per wheel (for $85, they better!). Hmm, actually at 50A durometer the rollers might rip themselves apart... though it may be worth some offseason testing nonetheless.

[mathman05]

Originally Posted by JesseK

I believe he means strafing while on the ramp, not strafing in order to climb up the ramp. In any case, any sort of drive train will have issues climbing the bump at an off angle unless there's a suspension system. At an off angle it's guaranteed that at least 1 wheel will come off of the ground. If you want to go mecanum and climb the ramp, you will have tradeoffs to consider regardless of how you design it.

Right, sorry. You are correct.

There was a team, though, that posted a video of strafing while on the bump. I forget who posted it at the moment. And I don't see how the metal sides of the mecanums would get in the way of strafing like that.

However, if any robot is caught sideways (meaning your drive wheels are parallel with the bump) (it's probably bottomed-out, firstly) on the bump, it's pretty much immobile until someone hits it off the top of the bump. Even then, you will likely roll over when you get pushed off (unless you have omni's (with large rollers?)? and if you have mecanums, it will be less likely, but still likely) At least, that's what I think.

In other words, if you're going to go up the bump, don't try to go over diagonally; things may not work out the way you want them to.

[efoote868]

Team 868 fabricated wheels like that for the 2006 game, Aim High. We were not able to go up the ramp at any angle other than head on, and once on the ramp we were not able to strafe from side to side, there was too much slippage.

Here's a picture of one of the wheels:
http://i111.photobucket.com/albums/n...te/5wheels.jpg

To be fair, I believe the ramp surface that year was diamond plate, so with a different surface you may have different results.

Best of luck.

[smistthegreat]

Does anyone know where i might be able to purchase some small (<4" Diameter) mecanum wheels. They dont have to bear any weight or do anything cool, just be small mecanum wheels. The cheaper the better

[joek]

i don't think anyone make small mechanum wheels, except for FTC, you'd have to make your own to get small mechanum

[Jon Stratis]

I think your best bet is going to be making your own, if you have the capability.