Those side slipping wheels are cool, but just wondering. Did you run into problems with being pushed form the side? or on a sideways incline (I know you shouldnt have been sidewats last year, but it wasnt unheard of)

Just seems that while nice they would allow you to be pushed around alot.

Team 95's six wheel drive
 

Your 6 wheel drive design with the center wheels a little lower than the front and rear wheels is a good way to make a machine that will turn easily while having good traction.

I suspect that you have learned enough from your machine that if you do another 6 wheel drive machine, the "chain popping" problem will be gone. While I saw your machine, I don't remember what chain you used, but if you use #35 chain, you should have no problems. It won't break and is a little tolerant of less than perfect alignment.

Good luck

We used the side slipping wheels on the front of our '98 and '00 machines, and the machines could be pushed sideways more easily than if the machines had wheel chair wheels at both ends. It turned out that not much pushing occurred in the '98 game and most of the pushing was fore and aft in the '00 game. Your point is a good one, though. In a game where robots could be pushed sideways to advantage, the side slip wheels would definitely be a compromise.

I know for the 2000 compeition on 308, we used plexiglass/aluminum sprockets. If you look on the link below, you can sortof see the wheels. (They look blue because it each wheel was 3 layers, 2 plexiglass layers with a aluminum layerin the middle) The reason we made those up was because we could get excellent traction going in forward and reverse, and provide enough side slip so we could turn. The problem we found using the wheel chair wheels in a 4 wheel drive system is they don't give much side slip, and make it very hard to turn. This puts alot of extra strain on the motors, and would cause them to overheat/burn out. This also put more of a drain on the battery due to the extra amount of work needed to turn the machine.

http://www-personal.engin.umich.edu/...irst/hang2.jpg

I know many, many people are going to disagree with me on this one, but I cannot stand wheel chair wheels. When used as drive wheels, they slip easily and more effective wheels can be quickly and cheaply made. When used as casters, they wobble and shake unless extremely well aligned. But, that's just my personal experience with them. Those of you who do like them, please say why. I'm sure there's some method to your madness. ;)

~Tom Fairchild~, who wished other wheels came with the materials kit so teams would not be so inclined to use bad traction wheels.

on 388 last year we used the neoprene rubber mat from small parts that had a diagonal pattern in it that was deeper than normal timeing belt wraped around 2 wheelchair wheels then sewn together with nylon thread as our traction... it looked like super wide mud tires and woked very well for a 2wd robot

Re: Team 95's six wheel drive
 

We used 6 wheel drive last year. It was very reliable, and we didn't have any problems with it. It also did a really cool spin move where the two goals would lift off the floor.

coefficient of friction
 

I was just wondering if anyone knew coefficient of friction of the standard 8�h skyway wheel company? I was also wondering how you test the coefficient of friction for a tire?

Thanks,
Kirk Oden

We built a test jig last year to compare the friction/traction of different wheels. We drove a wheel on a spring loaded moveable platform. We used the amount of the spring stretched to determine which wheel had the best traction. We found that our cleated wheel gave us the best traction.

Andres

Can use ANY wheels from Skyway this year...
 

If you haven't yet, take a look at the various wheels available from Skyway's web site(the URL is in the manual). There's just an unreal assortment of wheels available there, and the AHL this year says we can use anything that Skyway has to offer...

LoL, our rear wheels? Yeah, check out the attached picture. The story behind our rear wheels goes like this - we tried everything to get the most traction, and I mean everything. One person even took a 4 inch wide strip of lexan, cross cut it multiple times with around 1 cm between each cut, then did the same thing twice more on 30 degree angles. This worked great on carpet, but was horrible for making it over the small metal strip on the bridge. A mentor came across these little rubber stoppers and we tried them. Sure enough, they had the highest u value (coeficient of friction). At competition teams would ask us about them and by the end of Friday, there were many wheel chair wheels around with little black stoppers screwed into them. ;)

~Tom Fairchild~, who's looking through the catalogue of new wheels this year.

Last year we used the 8" wheelchair wheels. Each side had a common chain to drive the pair of wheels. The propulsion was provided by the drill motors. To get traction, we groved tread into them using a 'V' shaped tip on a soldering iron. They were awesome. We could tow the stretcher as easily as the goals. We could also turn on a dime.
My fondest memory of this system was when we were in a qualifying match at EPCOT. There was a disabled robot on a stretcher. We latched onto the stretcher, pulled it over the bridge (with no loss of traction), pulled up to a 10 point ball, picked up ball, pivoted 180 degrees, dropped off stretcher and than placed the ball on a goal. IMHO, it was poetry in motion.
So the wheelchair wheels are a viable option for drive wheels. I don't think they will work this year do to possible heavy side loadings. Wheels are made of plastic.

Tink, Tink...$.02 hitting computer screen :)

Wayne Doenges