Traction
 

What is everyone planing on using for traction? We have an awsome two speed coustom built motorcycle style tranny for the Chippys but im worried that our two 6inch dia 3 inch wide wheels wont provide enough traction and start to slip:confused:
Things to keep in mind: F=uN (formula for force of friction) notice no variable for surface area!

Sounds odd but we are considering using the old classic wheel chair wheels that have been in the kit forever! Go figure our design?

F=uN is only an approximation...

More than that, carpet damage may be some team's limiting factor. In this case, surface area is huge.

Just food for thought.

Joe J.

Us? We're using a high surface area mechanism *it's a secret soon to be released* with a coating of Neopreme conveyor belt. Great stuff. We have about 16 sq. inches of surface area for each side of the secret mechanism. This thing is a beast. More to come...

Word
 

That Neoprene Belt you speak of... i think we are and have been using the same stuff on our wheels for years... its from mcmaster car correct?

Thumbs up to Neoprene Timing Belt!! We just ordered it and I can't wait for it to come in. We ordered 1" wide with a 3/8" pitch, throw in a few little nails....oh man...

Does anyone else have any suggestions for wheels with A LOT of traction?? Is anyone making their own wheels, and if so, would you mind telling me out of what? (we're trying to make 2-3 sets of different wheels, and everythings interchangable :) )

I'll Private Message you.....

Littledave....yup, the same. Great stuff. 122 I think uses that stuff almost every year. We just decided to order a material for traction instead of making it ourselves...

Better get spare motors ......
 

Too much traction can be a baaaaaddddd thing too depending on what drive system you've chosen.

Don't forget, stalled motors become high current toasters at full voltage.

-and-

Tank tread designs need some slip in order to turn.


I hate the smell of burning motors on competition morning .......


Better get a line on some spares!

:rolleyes:

I can attest to that!!! Last year we had really cool and hard to build treads. The only problem, is that we had no slippage. So, we'd try and make a hard turn and the fuse would break and it'd take a second to go again. We even just forgot about getting the goals, we couldn't turn with them. This year's is much better. You'll see....

Are you planning on shifting on-the-fly? Would anyone that's trying this be willing to post drawings or explain how you're doing it? I believe team 67 was showing off their pneumatic-powered transmission last year but I can't remember how it worked.

Thanks.

shift on the fly kinda
 

In our tranny we can shift while moving we just have to write into the program to stop the chippys while the valve fires. I dont have the drawings for the tranny, one of our mentors designed it from scratch and built it in 2 weeks, under 10 lbs a peice and 2 speeds aprox 3 and 12 fps. It is a continous mesh motorcycle syle transmission. Thats all i can say right now. And to connect to the atwoods a shaft was put over them with the exact cut out of the teeth in it.

We won't really shift "one the fly" because we're changing between going 9 fps to 1 fps. Big change....

Other usage for "Belt"
 

Question: If we use regular "belt" (not timing belt) that is cut apart and glued to a flat surfaces (i.e. a flat plate), is this now allowed in the rules?

There has been some considerable talk and rule changes.
I know the "timing belt" restrictions have been changed, but
I was wondering if the initial "belt" usage restrictions of "any length, any type" has been changed since the kickoff.


Neill Means
Team #933

Belt - Any type, any length

This is still in the Additional Hardware List. Timing belts are included.

traction
 

we are using the neoprene CUSHIONING that comes in the mats...we used it last year..stuff is unstoppable..wait u'll see

This is actually wrong because I asked FIRST and they said you could not use any type!!!

Right, they were talking about timing belt that you can't use any type...Anything else you can get anything any size as long as the product has "belt" in it. This happens to be, conveyor "belt."

Well, three years ago we used Mectrol timing belt with high friction material on them. That was overkill, we hopped (yes, jumped a little) when point turning and burned out the motors. Two years ago we used the wheels that come in the kit, with no modifications - not enough traction for this year, but not bad for that game. Last year we used Mectrol belts again, this time without the high friction stuff. They were too slick, so we melted a criss-cross pattern on them with a soldering iron and roughened them up with abrasives, but we still didn't get quite enough traction to pull two goals up the ramp very well. This year we're using Skyway wheel hubs with rubber knobs from SPI (don't know what they're called) placed all around them. We've seen teams use these in the past with success, so we'll just find out how they work for us.

It seems like a lot of people are going to be using treads?

I think we're using the wheel-chair wheels Kacz100 mentioned previously. Bad part is they have really, really bad traction.

Anybody got any ideas??:confused:

Wheels
 

Skyway 10"x3" wheels are great.
Just use a belt sander and take the curve out of tread.
The result is a soft flat rubber tire that reminds me of an Indy Racer. ~14:1 geared Chiaphua's can turn 360's but only twice before popping the 30Amp breakers. You can't push the robot sideways. Ground clearance is 1/2". Wheels are on 3/4" shafts with thrust bearings to handle side loads.

rubber bumper treads
 

We're a rookie team, #802 and have been experimenting with various wheel and tread materials. The best we've found so far are the Small Parts 1" rubber bumpers (with steel washer) attached to a plywood sandwich wheel. The only trouble is that they don't seem last too long under extreme pushing or pulling conditions (ie. as we're spinning our wheels against very large loads). The carpet stays intact but the bumpers slowly disintegrate into black powdery dust and eventually come off completely as they wear down.

Does anyone have any insight or solution to this specific issue?

Thanks in advance,
Jeff

Coordinator and chief engineer for "The Lost Bearings". Lincoln-Sudbury High School, Sudbury, Ma.

Use a different material.

Anyone using unmodified Skyway Wheelchair wheels and feel that they will have enough traction this way??

We have been debating whether or not to modify our wheels =\

We tried the skywheels without modification and they seemed very slippery on the carpet. Our drive train is geared prettty low so our speed is about 5 feet per second.

We then roughed them up with a rasp and essentially flattened them at the same time. This was much better but still not good enough for our goals. We are experimenting with various treads and wheels now. I'm still not sure where we will end up.

Jeff

I have seen 'many' teams take a soldering iron to the wheel chair wheels to actually burn in a tread pattern. If I was using them at the minimum I would make them flat then get a tread pattern on them. If you are using 4 wheel drive, greatly enhance the traction on only 2 otherwise your robot will 'hop' trying to scrub off the traction to turn. There are a few rubber mats from small parts that can be applied to the outside circumference of the wheelchair wheels (glue + screw) that worked great for us in 2000. Also if you are going to do that and you chassis allows consider putting 2 wheels side by side then traction mat across both to make a wider wheel. Just remember about putting high traction on all 4, you have to overcome that to turn

Good Luck

Woo Hoo
 

We drove around for the first time with our bigger 4" wide wheels today and i no longer have fellings of doubt about our 2 wheel drive not getting enough traction! And our goal grabing mechanism (The Sickle of Death) is working beautifly.

if you do not think tracks are a good way of going ask some of the teams that went to Quincy.


With four motors that drive the track. the traction we got with our belts were great.

we moved anyone at any time without blowing breaks and without getting our motors even hot. we went 4 rounds back to back and the motors stay just warm. never did we blow a breaker.


and never lost a match. 5-0

we have now retaught our plans of picking up balls.

We now look like we will put our eggs in the basket of power and grabbing.

Can't wait til KSC

Recommend you test your wheels thouroughly on a carpet surface if you are using a belt as traction. We used a timing belt and attached it using epoxy to some wheels we manufactured out of aluminum and our drive had so much torque the belt delaminated and came off. So now we have come up with a much more secure fastening to the wheels and switch belts

Bleh!
 

damm Marcos, dont give away all our secrets!

Hmm, i see all you guys saying "we have 16 sq in." or stuff like that. well, my team has something close to i believe 194 sq in. i won't tell how, why, or what, but i will tell you that we have insane traction. :D

Yes Ian, but can you turn?
We had four 5.75" cylinders covered in conveyor belt material and we COLUD NOT TURN (23 sq inches on the carpet) :( So we made two new cylinders without material and grooved them. We can hopefully turn now.

Wayne Doenges

I suppose it may not be popular to point out the fact that traction really doesn't have anything to do with contact surface area. The only ways surface area will help is that the weight of the robot will be better distributed over the area in contact with the ground. Also, if the treads dig into the carpet, then an additional surface area will help. I'd be much more concerned with getting more weight over my drive wheels than maximizing surface area.

Matt

Speaking somewhat for Ian . . .

Yes, we can turn :) It may, however, be that turning and the 1 sq. ft.+ of area are mutually exclusive. A minor setback, perhaps, but nothing terribly, I think.

We'll get some pictures up in the gallery soon.

Matt: It's a beautiful thing. Friction is our friend.

traction paradyme
 

The more surface you have the less traction you have!!!!!\

Counter intuitive????

If you stand on one foot and weight 200 pounds you have all your force on one foot and your greatest possible traction. If you stand on two feet now you divide your weight to 100 and 100 and have less traction on either foot. The more surface you apply the less traction you have in any one place!!!!!

turning
 

We have 8" wide drums covered with industrial conveyor belt material. Not only do we NOT have problems turning, but we can push over 600 lbs worth of goals and people in them as well.

We did a lot of testing of surface area to traction. We spent a long time on this and discovered that with some materials, grip to the ground can increase with surface area.

The best way to think about it is like this. It took a lot of convincing to get the team to get it. But some materials act like velcro on carpet. Now which would you say is harder to pull apart, a one inch section of velcro or a 8 inch section? The 8 inch section can really be hard to pull apart if it's deeply imbedded in the mating strip of velcro. We shall see how it does in competition.

Jeremy

JUST LOOK AT MY TITLE!!!!
 

YES, true the paradyme is true but one also has to tak e into the counter force pushing back as the weight moves foreward. In turn, appliing a whole lot of dependence on friction instead of downward force on your drive train in a small area.

being the bruteforce specialist, and having my docterate on the subject i know that having downward force is not the equivelant to have traction (friction is).....in otherwards we used friction to achive the same outcome.





"MY NAME IS MATT FOLEY AND I AM A MOTIVATIONAL SPEAKER!" Cris Farley (matt foley SNL)

AND JUST TO TELL EVERYBODY THE
ROBOT'S NAME FOR TEAM 810
(though unnaficially)
HAS BEEN CHANGED TO....

THE MOTIVATIONAL SPEAKER !!!!!!!!!!!

Hmm, steve looks like he's going either through robot withdrawel or going hyper on his new found web site. well, i won't complain. :D

Oh dear.
 

Oh no! Steve found Chief Delphi!!

Run for your lives, and pray this site isn't held together by wire ties!

OH NO!!! KEEP STEVE AWAY FROM ANY SHARP, POINTY OBJECTS!!! HE'LL CUT ALL THE WIRE TIES!!!!

lol, that was funny... steve, and the compressor, and the wire ties...lol. :D

eliminate the choice
 

i know there is a fine line between awesome tracktion w/ torque and little traction with good speed. we beg to differ!
how we do this i cannot tell but i can give a few monster specs!

196 square inches of traction at 4fps
16 square inches of traction at 9fps

________________________

JUST FOOD FOR THOUGHT!

WAIT A SECOND WAS THAT LAST POST TRUE?





I DON'T KNOW!! DO YOU?


WHAT ABOUT THE FORMALITY OF SPEECH?

AM I MAKING SENSE?
IS THIS THING ON?
IS 810 REALLY JUST A LIEING ROOKIE TEAM?
YOU'LL JUST HAVE TO FIND OUT IN THE RING!!

U KNOW Y?
BECAUSE...................
WOOOOOOPS GOT TO GO!
I JUST FOUND A WIRE TIE THAT NEEDS CUTTING!!!!! SUPER STEVE TO THE RESCUE!!!!!!

our traction
 

our team is making our own wheels from 6" round stock aluminum. we customized them with meat tenderizer treads we specially sut into them, and spokes that are pretty cool. I am gonna get a photo of them soon and i will post it.:)


Greg
(badjokeguy)

Re: traction
 

wow....i remember when marcos said that, hehe, we were wrong