Re: Omni Mania
 

www.kornylak.com


Good omniwheels. bearings in the rollers, polyurethane rollers, aluminum construction, the works. Expensive, though.

Hey Bill, how 'bout the real thing ;)

After shaking off some of the dust, here's a link to our 2002 Inventor submission (thanks Kristin).

http://www.wildstang.org/ws/Inventor/2002/

hey thanks aflak

thats the site i found i preffer the cheaper transwheels alot better on the site

anyone have any where else to buy them?

Erm, careful with those cheaper wheels . .
One type (50 dollers) is all aluminum and has built in bearings, both illegal for FIRST use and not easily driveable. The others are all plastic. Be careful that whatever you buy will meet your weight/stress requirements. A 2 inch plastic omniwheel will not support a 130 lbs robot.

Moneys Worth
 

but 12 four inch 4000 series wheels just might hold :: plans & schemes :::

Omni wheels
 

We started the 2002 season with 4WD and skid steering, but not enough power. Immediately following a regional, we manufactured two omni-wheels for the front of our machine and added a swiveling tow-bar. With this progression I can offer a before and after viewpoint.

Pros:
Manueverability: Our 2002 machine went from an unturnable beast to a spinning, driving wonder (comparatively, at least).

Cons:
Traction loss. Our design had to replace existing wheels, resulting in 20 nylon rollers arrranged on the perimeter of an 8.5" aluminum disk. At any time there were perhaps 3-4 rollers 'biting' into the carpet (we left sharp edges on the rollers for just this purpose), but there was some traction loss compared to the original, rubber wheel.

Rough ride. As a new roller came into 'bite' there was a bit of a bounce and a lot of clacking noise. On carpet it was sufficient.

Maneuverability: Double edged sword. Another robot could ram us on either front side and redirect our efforts.

All in all, those omni wheels made for a MUCH better machine. Consider carefully what you give up for what you lose.

Good Luck

Out of curiousity, does anyone know of any team that ran 4WD skid steering with all omniwheels?


I can't recall ever seeing that done before, and while I understand the problems associated with that strategy, I'm interested in learning how it might handle.

Omni History
 

Do you mean a robot that was entirely composed of omni wheels... cuz as far as i know it hasnt been done ,of course i wont mind being the first:D

but if there has been id like to know from who and when and how it went

I believe that in 2002 MiM (343) had a mode that did this.

MiM had 6WD Omni.
They had 2 wheels, 2 wheels, 1 wheel, and 1 wheel on the sides of the bot.

So this bot wouldn't perform like the one Maddie is asking about.

Maddie - I've never heard of anyone making a bot like this. I can't imagine why anyone ever would... it would be too easy for someone to man-handle you all match simply by pushing you sideways.

John

You should know me better than that by now ;)

We started the first regional with that setup in 2002, it let the robot fly around the field but as stated above, it also let the robot get pushed laterally easily. We ended up putting two traction wheels on the front and left the omni's on the back and that worked well

Pushing too hard
 

this being pushed around, is it as bad as they say for teams using omni wheels or even crab drives?

i saw alot of footage involving 111 in alot of the regional matches and they zoomed across the field tho i did see some bots give them a few pushes in the wrong directions 111(wildstang) did lil work of them and zoomed thru the field evading and getting out of tight places and rough bots? so i mean is it that easy to take out such fast and maneuverable bot? video says contrary but i suppose it also depends on how good the bot ends up being

Re: Pushing too hard
 

We are talking about omni-wheels.
Wheels that allow for lateral motion.

Basically, if you use 4 omni wheels there is NO friction in the lateral direction. This means someone can push you sideways across the field with little or no effort.

As far as Wildstang's drive...
They had a decent amount of traction, they just weren't geared low enough to win a "straight pushing match" they relied on maneuverability and their cool wedges. They could have pushed, if they were geared lower. (Shifting swerve drive anyone?)

Hope this helps.

John

Since we're on the subject of Omni-wheels, I should mention that there is a new white paper on this subject. It's called TechnoKat Trick Wheel.

This paper includes a detailed mechanical print package for an "omni-wheel" (we call them Trick Wheels). The one in the print package was used in 2003. The designer & developer of this module is Mark Koors, TechnoKat & Delphi engineer.

Andy B.