pic: First Mecanum Drive

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[Chris is me]

I like the nice and simple design. If you do decide to pursue mecanum this should serve you well - a nice low CG, rigid frame for bumper mounting, and easy adjustability and mounting for other subsystems.

Have you looked into the Toughbox Nano Tube or similar designs? It might get you a more rigid solution.

[Andrew Schreiber]

6" or 8"? Either way, why is your frame so high, this year is on a flat surface (or near flat), drop that frame underneath it and give yourself a lower CG.

I assume those are TB Nanos, what are you looking at for gearing?

Have you read Ether's paper on controlling these suckers?

Field Centric or Robot Centric driving?

[liam.larkin]

Simple I always like simple. I must concur with my buddy Chris is Me. Look into the Andy Mark Nano Tubes just a suggestion but not necessary to build a very functioning mecanum drive system. My FIRST team (272) minus 2009 because they would have been illegal has used mecanum since 2007 and we are in love with them. Software and a Rigid Squared Structure are the keys to success here. If the wheels begin to candum your control, especially in a crab (side to side) motion becomes sluggish, innacurate or drifts in an undesired direction.

If you need help with the code please email me and I can show you what we have been using for years. We code in C++ by the way. irishpridel@hotmail.com

[jblay]

We are using 6" wheels with an 8.45:1 ratio.

The programmers are still deciding but it looks like we are going to go with robot oriented drive.

We are making it this high off the ground because we wanted to mount the nano right off of the chassis so that it could be as close to the wheel as possible and because it is a nice rigid place to mount it. I wanted to essentially flip the whole thing upside down but everyone thinks that the chassis being a 1/4'' off the ground is too little and it would cause the chassis to drag on the carpet and I might be forced to agree with that.

With regards to the nano tube we think ours will be rigid enough to be fine at competition if not more rigid than the tube because we will be able to support the shaft from the gear box on both sides of the wheel. Also our way gives us a really nice place for mounting bumpers and with west coast like drivetrains that is always an issue.

[Ether]

Originally Posted by jblay

The programmers are still deciding but it looks like we are going to go with robot oriented drive.

Why are the programmers making this decision? I would think the drivers would make that decision, with the advice and consent of the rest of the team.

[jblay]

Originally Posted by Ether

Why are the programmers making this decision? I would think the drivers would make that decision, with the advice and consent of the rest of the team.

Well I forgot to mention in combination with the driver.

[Colin P]

Make sure your frame is solid. I've heard from teams that have had problems with mecanums functioning properly with even the slightest wobble in the frame. If you use the kit metal, I'd recommend gussets and steel pop rivets instead of the hardware they offer.
Especially with the 6" wheels, the plates can dig into the carpet and prevent strafing and turning. Make sure there isn't any wobble in your wheels!

[Alan Anderson]

Originally Posted by Colin P

Make sure your frame is solid. I've heard from teams that have had problems with mecanums functioning properly with even the slightest wobble in the frame.

Actually, a flexible frame helps keep all the wheels on the floor. If it's too rigid, any deviation from a perfectly flat surface will let one wheel lose traction and control will suffer badly.

What you really want to do is control weight distribution. Try to make each wheel carry the same amount of weight. That will make it a lot easier to keep the wheels spinning the way you want them too.