Re: pic: Another concept study
 

Yeah, but you forget to mention only 3 of your wheels were on the ground at once. Aaron =/= trusted source on mecanums.

Re: pic: Another concept study
 

My software-addled brain is having trouble visualizing how face-mounted cylinders can follow the arc the traction wheels make when extended downward.

Re: pic: Another concept study
 

It looks like they aren't facemounted, but rather front pivoting cylinders. The crossholes in what appear to be the mounts must be what they rotate on.

Re: pic: Another concept study
 

What ratio were you using? As Andrew suggested, That sounds more like a problem with the implementation than with the gearing. Our 2011 mecanum drive was around 8:1 and we had plenty of torque and speed to strafe. And besides gearing for torque on mecanum is like gearing for torque in Lunacy, you have just above no pushing power (in most cases) so gearing for high torque doesn't really do anything except slow you down and make you easy to defend against.

Re: pic: Another concept study
 

You are correct - the cylinders pivot.

Last year we did use fixed cylinders with the traction wheels. The arc error was only about 0.010" so we made the holes oversized to accommodate it. With this concept the tractor wheel rotates too much for a fixed cylinder.

Re: pic: Another concept study
 

When we run a simple Mecanum drivetrain we run at around 9 fps. This seems to be about as fast as you can go and still get maximum pushing force from the Mecanums.

Last year we ran at about 10.7 fps and had no trouble. With the traction wheels we don't need to worry about the Mecanum's lower pushing force so we can run faster.

This concept is at 13 fps but that doesn't mean we would ever build it that way. Our driver said he didn't go to full speed at 10.7 fps very often so faster than that would have be a need driven by the game.

Re: pic: Another concept study
 

I love this design (and the detail in the model), but I cannot see how are you going to make the hollow round housing like that for the traction wheels? I am sure I am missing something but it looks like it is just machined from one solid block of aluminum.

Re: pic: Another concept study
 

Yeah - that one is a bit messy. I have it designed as a tube with end plates welded on and then machined.

Re: pic: Another concept study
 

I would recommend changing the setup so that the pivot is on the traction wheel and not the mechanum. The reason is that you will see a large bending force on your pivot if you are in traction mode and you get pushed from the side. The distance from your traction wheel to the pivot will act as a moment arm and can reek havoc. Now you are using box tubing which has a great bending strength, but you are also using that same box tubing to house a gearbox, so even a slight bend can really foul up the works.

This is a lesson learned from experience on 148. Take a look at the differences in the drive train between 2010 and 2011.

Re: pic: Another concept study
 

With what program did you make this with? About how much money is it to have the program and how much skill is needed to create this?

Our team is looking into this kind of designing.

Re: pic: Another concept study
 

I used Creo Parametric 2.0. It's free to First teams. It does take skill but no time like the present to start learning.

Re: pic: Another concept study
 

Does this program come included in the Kit Of Parts? Or must we request it separately? Also, how do you get FIRST pieces into the program (ex: the CIM motors, omni wheel)?

Re: pic: Another concept study
 

Start here:

http://www.ptc.com/company/community/first/

Re: pic: Another concept study
 

I don't see the FIRST KoP on there (Tom's PTC link), so I'll just mention that you can get the files from Autodesk FIRSTbase (you want the STEP format if you run Creo). AndyMark and McMaster-Carr also have a lot of CAD files available for their products.

FIRST teams have access to a lot of free CAD software: Autodesk Inventor, Creo, and SolidWorks, at least. You can do things like this in any of them, if you practice! People here would be happy to help you (but you'll want to find/make the relevant threads).

...

And now back to our regularly scheduled ogle-at-octocanum thread. This is gorgeous! I never even thought about doing a concept study like this; brilliant insight. What's your cylinder bore?

Re: pic: Another concept study
 

I've been studying the details of this render in several sittings, and I'm still in the process of absorbing some of them. This is really neat stuff. Thanks for posting!

It looks to me like the speed on the traction wheels would be something like 3.5 times slower than the mecanums, based on wheel size difference and a guess that the traction wheel's gearing is about 2:1.