2015: Year of the Mecanum

[Ben Wolsieffer]

Our team has had a good amount of experience with mecanums, and we haven't any big problems with bumps. We used them in 2010 (w/o suspension) and were able to climb over the bump, and also in 2012, where we were able to easily climb the bridge.

Based on that experience I think driving over the scoring area won't be a problem at all.

[Mecanum Wheel]

Originally Posted by chrisfl

It was the same for us. We used mechanum in 2012 and our only problem was staying in one place on the bridge. We had no problem going up and down it while at an angle.

Originally Posted by lark95

My team is also thinking of using mecnum drive. we even have an old robot from logamotion that used mecnum we are able to drive

Originally Posted by theCADguy

Also, quick question:
Can a mechanum drive be set up where the length of the drive train is greater than the width, or does it require a square wheel configuration?

Originally Posted by JosephC

If you have not prototyped mechanum or done it before, I would not recommend bringing it out this season. It doesn't seem difficult at first, but you will end up spending far too much time on your drive train instead of allocating proper time to your mechanisms.

*mecanum

[ratdude747]

Originally Posted by Kevin Sevcik

For the record, we tried mecanums in 2008 and 2009, and just the plywood under the carpet would make things go wonky if you were trying to do a precise alignment.

I'm not saying they'll be undriveable, I'm just saying they're going to make auto and certain precision tasks a wee bit more challenging and error prone than they need to be.

Unless you're talking offseason prototypes, I highly doubt that *cough *

[Kevin Sevcik]

Originally Posted by ratdude747

Unless you're talking offseason prototypes, I highly doubt that *cough *

I've been doing this too long and I'm starting to get confused. 2010 and 2011 is what I meant to say there.

[lark95]

My team is also thinking of using mecnum drive. we even have an old robot from logamotion that used mecnum we are able to drive

[AutodeskGeek]

Originally Posted by Ether

My guess is this won't be a major issue with a properly built and driven mecanum.

Amen to this. The only trouble we had with mecanum was the bridges in 2012. It wasn't impossible, we still balanced. Since it's only a 16 degree angle, it shouldn't be impossible to get over it.
Breakaway year, they had larger bumps. We went up them fine with mecanum also. Given, they were carpeted.

Some teams will struggle with the mecanum, some won't.

[Jalerre]

For those talking about driving over the bumps, I do believe that is prohibited. Don't quote me on this but I think it says so somewhere in the manual. Their primary only purpose is as a scoring platform so you don't need to worry about how mecanums are going to get over the bumps.

In regards to programming mecanums, I can say from experience that it is really easy. Our team has used them for the past 3 years. Both Java and C++ (I can't speak for Labview) have methods for programming a mecanum drive (2 methods in fact, at least in the 2014 library). Just plug in your parameters and that's all there is to it.

Finally, though I didn't agree with my team in the past about a mecanum drive train, this year I can really see the advantages. Because there won't be too much robot-to-robot interaction you won't have to worry about pushing power or traction. Also strafing will be really useful when you need to line up to stack the totes and recycling bins.

[nicholsjj]

The code in labview is a canned VI. The only problem that I have had to help teams with is many younger teams make the rotation the throttle axis. Most of the time I have them switch to a button switch statement for turning and it works out fine, some still like other axis turning methods and it can be worked through with the Get axis. Our team has decided to use Mecanum since the no defense is in play and we might try to go for the stack in auto. Mecanum will work out nicely for strafing left or right and picking up as long as you use a gyro for drift. The only initial issues we are concerned with is the frame spacing for the totes and going over the scoring platforms. We think 8" HD's will be fine enough to prototype though.

[Ether]

Originally Posted by Jalerre

For those talking about driving over the bumps, I do believe that is prohibited.

The game reveal video at 1:13 shows a bot driving over the platform.

[jtrv]

Originally Posted by Ether

The game reveal video at 1:13 shows a bot driving over the platform.

He might have been talking about the middle platform, but yes, the scoring platforms can be crossed.

[Ether]

Originally Posted by jtrv

He might have been talking about the middle platform

In the given context, that wouldn't make sense.

Also note that the middle is called a step, not a platform.

[Jalerre]

Originally Posted by Ether

The game reveal video at 1:13 shows a bot driving over the platform.

I didn't see it in the manual anywhere that's just the conclusion that our team had come to. (I didn't try to confirm it I just trusted them)

[craigboez]

If you have 3 rollers on the carpet and one on the hdpe, does the coefficient of friction come into play? I assume as long as you don't break traction on any of the wheels you can effectively transmit force vectors to the ground?

[theCADguy]

Originally Posted by Jalerre

For those talking about driving over the bumps, I do believe that is prohibited.

I believe that you are thinking of the step in the middle. You can traverse the scoring zones, however.

Also, quick question:
Can a mechanum drive be set up where the length of the drive train is greater than the width, or does it require a square wheel configuration?

[StephenNutt]

Originally Posted by theCADguy

Also, quick question:
Can a mechanum drive be set up where the length of the drive train is greater than the width, or does it require a square configuration?

You can set it up with any aspect ratio, square, long or short (within reason)