Traction

[Stephen Kowski]

If I were a team going into one of the next regionals I would bring something to increase traction because we had problems with traction until we put on our treads and were reweighed.

what did you have before you put treads on

[Ricky Q.]

We won't have that problem Treads and wheels are the way to go for us

[Stephen Kowski]

just the bare wheelchair wheels, and we tested taking out sections in the wheel like other teams did with success, but no luck. So we put on the treads and were able to handle the goals better than we ever had before.

[Ken Leung]

I would recommend to teams that they re-think if they use plain skyway wheels or those giant black rubber wheels skyway sell.

Those wheels do not have enough traction compare to other material. You wheels will be slipping before you can push your opponents any harder, so you won't be able to take advantage of whatever gearing you have on the drive motors.

Go ahead and take teams' advices. Buy some belt material and put them around your skyway wheels. If you are worry about putting flat belts on the curved surface of the wheel, get a belt sander, hold the wheel on a hand drill, and sand it flat. Glue the belts on the wheel, and screw them it.

You can try out your drive train at the first practice round, put on better wheels, and try that out in the second round. See how much stronger you can push.

As most of you have seen, pushing is an important factor in this year's competition. There will be some matches where you can only win by pushing the other robot away, and that you will need traction. (Well, you will need a good amount of torque and momentum, but the plain skyway wheels are probably the ones to fail first, before stalling motors or whatever...)

Mean while, I am curious. How many teams lift up goals to gain more traction? Did they ended up having more pushing force because of that? Were teams not lifting up goals able to push away teams who did?

[George1902]

I only remember 3 teams that lifted on the goals to gain traction: 343, 179, and us

Anyone remember others?

George
S.P.A.M.
Team 180

[Perseus]

we push up on the goals but that is so its harder to move us when we plant.

[Stephen Kowski]

Originally posted by George180
I only remember 3 teams that lifted on the goals to gain traction: 343, 179, and us

Anyone remember others?

George
S.P.A.M.
Team 180

Oh I remember that Demolition Squad had a little bit of traction...

[GregT]

Originally posted by George180
I only remember 3 teams that lifted on the goals to gain traction: 343, 179, and us

Anyone remember others?

George
S.P.A.M.
Team 180

My team can lift the goals, how much dose it help? We have skyway wheels with notches milled in them, the goal's weight (most of it) will be on the 2 wheels touching the ground... i hope its enough traction to make a differance

Greg

[Ken Leung]

How much friction force you can get out of the wheels is pretty much determined by the weight and coefficient of friction. The friction force pretty much comes from static friction between the wheel and the carpet. Fs =< uN

This means you can exert a force of uN (or less) from the wheel onto the ground without slipping. u is coefficient of friction, which is a constant for whatever wheel you are using. That's why teams add other material around wheels to have a bigger coefficient of friction.

N is just the normal force from your robot. The heavier your robot is, the bigger the normal force the wheel and carpet will feel. That is why teams concentrate their weights on the powered wheels, and try to get to robot as heavy as possible.

With bigger u and N, your robot can push harder without the wheels slipping as easily. So, say, you are not lifting up goals. Fs is about 130u at most. If you lift one side of one goal, and put the weights on powered wheels, then Fs become about (130+90)u (lifting goals on one side is about supporting half the goal's weight). This add about 69% more possible friction force you can take advantage of from the wheels.

If you were pushing, say, 100 lbs before your wheels slip, now, you can push 169 before they slip.

Lifting two goal would mean adding 180 lbs on your robot, making Fs (130+180)u. 138% more possible friction force you can take advantage of. Now you can push 238 lbs before your wheels slip.


Traction isn't the only factor in your drive train, there are also motor power and current limit... With tons of traction, your robot will probably stall before your drive train slips on the carpet...

But, having more traction will still help out a lot if you are going to gear your drive train really strong, or add more motors.


I am curious, were the carpet damaged a lot at this last two regionals? Was there any Disqualification due to damaging of the carpets from wheels?

[Mike Norton]

I only remember 3 teams that lifted on the goals to gain traction: 343, 179, and us

We did not lift up on the goals and we pulled everybody even team 180.

Tracks are the way to go. We flip over heat wave and we flip team 59.

team 59 had big rubber wheels. and heat wave lift them self off the floor to get more traction.

if you pull from the bottom of your robot you will have enough traction to pull anything.


Why they flip over is because they had good traction so someting had to go and most of the time it was there robot.

Our strongest match was pulling heat wave two goals and there partner into our zone.

Power will win

I was happy to see team 180 win. I could not believe it took til the second round for them to get picked.

Power is what is going to win.

[Ian W.]

actually, we're using 4 beadlok wheels, and i believe we have too much traction. so, we had to spend all day today "detractionizing" our robot. not sure how it ended up, as i left a bit early, but i'm hoping we made it work.

[Perseus]

We are useing Holonomic wheels in the front. It is a regular wheel but it has washers attatched to it, perpendicularly(if thats a word). This allows you to be able to move side to side(on the washers) but, driven by th eChiaphus, we get lots of traction because flat end of the washers dig into the playing field when driven forward. I believe there is a picture of themon our website at www.moerobotics.org if this definition is too confusing .