pic: A mechanum wheel that shouldn't bump around at all.

[Brandon Holley]

Originally Posted by JesseK

Combining the two dominant Mecanum designs into a hybrid design may be a better solution. A hybrid design has 3 rollers with 2 thin mount plates; the two rollers on the outside look like rounded cones and are cantilevered whereas the roller in the middle looks more like a bulging omni wheel roller (or a squished donut).

Like the segway mecanum wheel??



-Brando

[,4lex S.]

I have been thinking about how you did this, and I have to say, you have me stumped. How did you design the 3D wheel with that perfectly circular side profile?

[Hawiian Cadder]

in actuality the arm will go all the way out, and match the profile of the roller and be coated in delrin, that will slide and will make it perfect, the way i did it was to assume that each roller had to have an arc that would look exactly like a circle when viewed from 45 degrees, thus the line that defines the outer edge of that roller is an elipse with one dimension being 8, the diameter of the wheel, and the other dimension being 8/sin(45) or about 11.3, this makes the profile of the roller a perfect circle from a 45 degree angle. the rollers are just revolves with that line as the edge. the arms are .375 inch thick 7075 aluminum alloy, and according to solid works, this wheel should hold at least 200 LBS safely. the total weight of the wheel is 1.8 LBS, it is 2.6 inches wide from roller tip to roller tip, and is 8 in diameter, the axle hole will have have a hub or something to attach it to the motor. the method for manufacturing the rollers is to print off a mold on our 3d printer, then use urethane, coated in rubber. overall it should be pretty sweet.

[KRUNCH DUDE]

These wheels remind me of Airtrax wheels, did you get the idea from them? I would like to see a nice set of mechanum wheels for FIRST.

[Rion Atkinson]

Originally Posted by KRUNCH DUDE

These wheels remind me of Airtrax wheels, did you get the idea from them? I would like to see a nice set of mechanum wheels for FIRST.

You can buy some from AndyMark.

[Hawiian Cadder]

true, the method that i used to make these could be aplied to any angle of mechanum wheel. when we build them we may use closer to a 35 degree angle,when strafing speed is nessisary, and they will climb better.

[Ryan Dognaux]

Originally Posted by KRUNCH DUDE

These wheels remind me of Airtrax wheels, did you get the idea from them? I would like to see a nice set of mechanum wheels for FIRST.

Do a search for Jester Drive. 357 has been creating mecanum wheels since 2005 (actually this thread right here has some good discussion in it - http://www.chiefdelphi.com/media/photos/20664). Gives some information on the development of our wheels and our relation to Airtrax.

I've attached a few images from this year's CAD renders, feel free to check them out.

[Rion Atkinson]

Originally Posted by Ryan Dognaux

Do a search for Jester Drive. 357 has been creating mecanum wheels since 2005 (actually this thread right here has some good discussion in it - http://www.chiefdelphi.com/media/photos/20664). Gives some information on the development of our wheels and our relation to Airtrax.

I've attached a few images from this year's CAD renders, feel free to check them out.

...

What program do you use to render those?

[Ryan Dognaux]

Originally Posted by Formerly Famous

What program do you use to render those?

That was done in Inventor 2010 by one of our students, Kyle Tress.

[Andrew Schreiber]

Originally Posted by Ryan Dognaux

That was done in Inventor 2010 by one of our students, Kyle Tress.

Ryan, do you machine your hubs from solid? I assume you cast your rollers?

[Joe Ross]

Originally Posted by Andrew Schreiber

Ryan, do you machine your hubs from solid? I assume you cast your rollers?

There's a nice description (with lots of pictures) of their 2006 process in FIRST Robots: Aim High: Behind the Design

[Ryan Dognaux]

Originally Posted by Andrew Schreiber

Ryan, do you machine your hubs from solid? I assume you cast your rollers?

The hex hubs are machined from hex stock and the outside fins that hold each roller are bolted onto the outside of the hub. This way, if we somehow bend a fin during a match (the bumps liked to do that this year), we can swap them out between matches with spares and you don't lose an entire wheel.

The rollers were cast with certain materials this year from silicone molds. The rollers themselves have two layers, a hard inner core and a softer outer traction layer. I'll see if I can get some of the students who made the rollers this year to post more details.

[Rion Atkinson]

Originally Posted by Ryan Dognaux

That was done in Inventor 2010 by one of our students, Kyle Tress.

Interesting... I've never seen Inventor render anything that pretty... Looks like I'll have to play with 2011 some more.

[Ether]

Originally Posted by Brandon Holley

Like the segway mecanum wheel??

Hi Brandon,

Could you provide a link that shows the rest of this picture? I am curious to see the rest of the platform.


~

[Alan Anderson]

Originally Posted by Ether

Could you provide a link that shows the rest of this picture? I am curious to see the rest of the platform.

That's the Segway RMP 400 Omni.