How can we drive on this new floor?

[Dracco1993]

Some of my team members and I calculated that using 2 sim's and suction cup properly you caould add an extra 600 pounds to your robot with ever touching the ground... Any Ideas?

[Koko Ed]

Originally Posted by Dracco1993

Some of my team members and I calculated that using 2 sim's and suction cup properly you caould add an extra 600 pounds to your robot with ever touching the ground... Any Ideas?

Shade of 2003.
Teams used suction cups to plant themselves at the top of the ramp. That worked for the first few matches and then after getting ran over by robots for a while the field surface got worn down a bit and the suction cups stopped working.
I suspect the same would happen this year as well.

[Mike8519]

Originally Posted by Homsar66

Think. If this were true, then weight could be "a form of traction enhancement", similar to any traction control ect. Meaning anything on the robot is outlawed, as it adds weight to increase traction.

Yes, weight does help traction, but it is a legal addition to the robot to a limit. Increasing your traction beyond your idle state/curb weight I think would cause the issue.

Traction control is legal because it is increasing control electronically. Not changing the physical interaction between the playing surface and the rover wheels

[Dracco1993]

Originally Posted by Koko Ed

Shade of 2003.
Teams used suction cups to plant themselves at the top of the ramp. That worked for the first few matches and then after getting ran over by robots for a while the field surface got worn down a bit and the suction cups stopped working.
I suspect the same would happen this year as well.

I see your point, but that math was done assuming that the suction cups are about 1/2 to 1/4 of an inch off the ground. They would be more like a hover craft in reverse then suction cups.

[Bongle]

A hybrid of propulsion and wheels is almost useless even if it is deemed allowed (which by the "no other traction on the field allowed" part of the rules can't be done anyway).

I don't think it is useless. The maximum force that can be generated with the wheels for a max-weight robot is 26.7N. With some math, you can determine that 5N and 10N fans could be plausibly added to your robot, which would add 18% and 36% to the acceleration of a max-weight robot, respectively. Some of that would be eaten by the airstream hitting the trailer, but I think a fan approach could actually increase performance.

I think there is a reading of the rules where it would be allowed. Traction generally refers to the contact between a wheel and the ground. Fans aren't enhancing your traction with the field (and unless you have a quickly reversible fan, they actually hurt your braking performance), they are applying a force by pushing against the atmosphere. However, there are also readings of the rules where it wouldn't be allowed, and it'll have to wait until QA opens to see if they are allowable.

[Dracco1993]

Last year we were one of a few teams that used a vacume to pick up the ball so we have some experience with them. One of my friends on the team picked up the ball just using his mouth. He sucked on a vacume tube atached to a cake holder lid. With that much of a surface area he could pick up the ball for about 5 seconds.

[johnr]

Does this make any sense? Six wheeled bot. Four corner wheels driving forward and two side centered wheels driving backward as needed. Or, one wheel dead center of bot that would spin oppisite as needed. Then hand the whole thing over to programers. They can make it work.

[vivek16]

Look, all the ideas with fans:

Why not take your 200 pounds of force going downwards, point that to a side, and use it as a means of propulsion? It would certainly be a lot more efficient than using the force to increase the traction (it will still be low traction).

-Vivek

[spiffyspleen]

Would a holonomic drive system work well? I think it would make it easier to drive, but I don't know for sure. Here is a link to a picture of what I am talking about except that we would have to use the required wheels instead of the omnis. The required wheels should work as well though, because they barely have any traction.
http://wiki.chiefdelphi.com/media/0/..._holonomic.jpg

[smartkid]

You would have to use the wheels in the kit as the casters, the wheel would be huge and bulky but it could work. Now you have to know that an omni-drive works on the principle of wheel slippage. It is designed so that wheel casters slip.

[usbcd36]

While this might make sense initially, holonomic actually starts looking very bad after viewing the COFs for the wheels.

10.2.4.1 Wheels
The wheels supplied in the 2009 KOP are very different from previous years’ kit wheels. The
tread material is Celcon M90, and has the following coefficients of friction on white, rippled
fiberglass plastic sheet
Inline, static: 0.06
Inline, dynamic: 0.05
Transverse, static: 0.14
Transverse, dynamic: 0.10

Yes, the transverse COF is very low, but the inline COF is less than half of it! This means a holonomic drive robot (with the COG in the middle) theoretically wouldn't move at all! In practice, it might, but not much.

[Adam Y.]

Originally Posted by robodude03

You are absolutely right. Drivers will need to train themselves and adapt to the slick situation. Additionally, I believe that programming will also have a big part in this years game (i.e. Traction Control). Our team will be doing a lot of testing in terms of the best method of acceleration for our robot, inputting that into our system and applying that to our controls.

That could be a problem. In general PID controllers have always been a robust and great way to move your robot. The problem is that the ideal way to control the motors is with some type of ramp input meaning that the integrator may or may not work as exactly the same.

[cj.reeves]

is the coefficient of friction independent of surface area or not?

i think more wheels equals more friction

[Zyck_titan]

Originally Posted by gorrilla

the rules specify that the Rover Wheels are the only thing allowed to provide "traction"

But the Fan is not providing traction, it's providing a weight force, making up for the lost 5/6 of weight

[sbrumund]

In simple physics terms friction is independant of the surface area.

In reality because we are on a textured surface it may not be.

If the wheels are the same as last years kit wheels the surface is a soft compound. With sufficient weight on each wheel the soft compound will conform the the bumpy surface producing more friction than a wheel riding on the top of the bumps.

The question then is what is then optimal load on a wheel to obtain the most friction. A simple experiment can be designed to determine the optimal loading and therefor the optimal number of wheels.

If allowed the vacuume design is possible. Many schools physics departments have a 4' diameter hovercraft where the lift is achieved with a battery powered leaf blower. The leaf blowers run well for 10 minutes on a charge and can easily support a 250 lb load. I believe the battery supplied has sufficient energy to power the leaf blower and drive motors and increase the normal force and friction. You would need a fully charged battery for each match.

Since we are simulating 1/6 gravity on the moon and there is no atmosphere on the moon I suspect a vacuume design wil not be allowed.

It is possible to get used to driving on a low friction surface. Those who are used to driving on ice and snow understand the limitations. Keep in mind that when driving a car on ice you are in the car and have a, seat of your pants, feeing of what is going. You do not have this sensor input at a remote driving station.

It is possible and easy through programming to limit how fast you can accelerate and turn. It takes some time to get used to, like the first time you slam on the brakes of a car with anti lock brakes.