Originally Posted by Kevin Ray (Post 1161091)

You are right. They are not Omni's. We've used both. Though they don't roll easily, they do roll. Try pushing a macanum bot sideways when it is not powered. What I was trying to explain to SuperNerd256 is that a macanum bot in most orientations would roll off the tilted bridge with no power applied to prevent it. And, while we are at it, given identical gearboxes and friction coefficients of wheels, macanums would lose in a head to head with conventional wheels. This is possibly what SuperNerd256 was referencing.

Originally Posted by Kevin Ray (Post 1161091)

You are right. They are not Omni's. We've used both. Though they don't roll easily, they do roll. Try pushing a macanum bot sideways when it is not powered. What I was trying to explain to SuperNerd256 is that a macanum bot in most orientations would roll off the tilted bridge with no power applied to prevent it. And, while we are at it, given identical gearboxes and friction coefficients of wheels, macanums would lose in a head to head with conventional wheels. This is possibly what SuperNerd256 was referencing.

Originally Posted by Grim Tuesday (Post 1161069)

Get in contact with team 357, Royal Assault. They debuted Mecanums for FIRST usage, and if there will be a Mecanum robot on Einstein, it will be them.

Originally Posted by jblay (Post 1161050)

Make a swerve drive setup.

In all seriousness though the real issues with the mecanum wheels in terms of pushing are this:
-They aren't 100% effective at transferring power, a lot of it is lost. This forces you to have to gear higher to be able to go at a reasonable speed which makes you less capable of pushing. It is difficult to do a shifting gearbox with mecanum wheels because each wheel has it's own gearbox and shifting gearboxes are quite heavy.

Hope this helps. As a team that used mecanum wheels last year I would advise against them because when the eliminations roll around and you are facing defense, being able to be pushed sideways easily really hurts your chances and it makes winning very difficult.

Originally Posted by SuperNerd256 (Post 1161102)

Kevin's right; That's what I'm referring to.

Originally Posted by Andrew Schreiber (Post 1161273)

Except Kevin is wrong. I've tried pushing unpowered mecanums sideways (software testing for 2337 in 2010). I was physically unable to push the robot sideways. Along the diagonals was a different story though. Still not easy but most definitely easier. None of this involved any sort of fancy software which would enable the wheels to hold position.

As for grippy mecanums, if you ever get a chance talk to 357 about their process. Their wheels have quite a bit of grip and they are one of the few teams I've seen use mecanums well.

However, I am a firm believer in the theory that if you are pushing with a mecanum wheeled robot you are doing it wrong.

Originally Posted by SuperNerd256 (Post 1161275)

I know Kevin posted twice, so maybe we're reading separate posts. I'm agreeing to http://www.chiefdelphi.com/forums/sh...1&postcount=14

Mainly the part about the mecanums rolling off a tilted bridge if the power was disabled, and how they aren't as good in pushing matches.

Originally Posted by Andrew Schreiber (Post 1161273)

Except Kevin is wrong. I've tried pushing unpowered mecanums sideways (software testing for 2337 in 2010). I was physically unable to push the robot sideways. Along the diagonals was a different story though. Still not easy but most definitely easier. None of this involved any sort of fancy software which would enable the wheels to hold position.

As for grippy mecanums, if you ever get a chance talk to 357 about their process. Their wheels have quite a bit of grip and they are one of the few teams I've seen use mecanums well.

However, I am a firm believer in the theory that if you are pushing with a mecanum wheeled robot you are doing it wrong.

Originally Posted by Hawiian Cadder (Post 1161300)

If the mechanum robot in question was running direct drive off bane bots P-80's then it is more than likely caused by binding in the gearboxes due to side loading. We had this problem in 2010, P-80's don't appreciate side loads at all, and without proper collars or flanges on the axle to load the frame instead of the gearbox this can cause inefficiencies for mechanums going sideways. I still wouldn't consider anything short of rough-top/wedgtop or pneumatic wheels to be really "high grip" in FRC.