How can we drive on this new floor?

[markulrich]

For tank drive systems, what do you guys think about 4 vs 6 coplanar, evenly spaced wheels? Would there really be any difference?

Has anyone felt the new playing surface? How much does it cost? Would plane old hallway concrete be a suitable substitute?

[Sam2197]

im not sure how many of you out there live in the lovely area that gets a lot of snow. but im in new carlisle indiana. and we just get dumped on constanlty. one thing i've notices is front wheel drive cars tend to do better. you can power out of the slide (if you are able to do a car-like steering). and i have noticed that rear wheel drive causes a lot of fishtailing.(maybe not with the trailer). but the best by far is four-wheel drive. it gives you power to all four wheels. team 2197 is without a doubt going with four wheel drive. good luck to everyone. i hope you all have fun with lunacy

[dtengineering]

One thing to watch for when designing the robot is turning ability when using skid steering (tank drive).

If you notice the coefficients of friction for the wheels, you will see that inline dynamic is .05 while transverse dynamic is .10. In a skidding situation the wheel will be twice as resistant to going sideways as it is to going forwards....

That means, as I read it, that your wheel is not going to want to slide sideways very easily if you use 4wd tank drive.

In fact anyone planning on going with skid steering will probably want to really look at using at least six wheels to minimize the amount of skidding required in a turn.

Jason

[writchie]

Originally Posted by dtengineering

One thing to watch for when designing the robot is turning ability when using skid steering (tank drive).

If you notice the coefficients of friction for the wheels, you will see that inline dynamic is .05 while transverse dynamic is .10. In a skidding situation the wheel will be twice as resistant to going sideways as it is to going forwards....

That means, as I read it, that your wheel is not going to want to slide sideways very easily if you use 4wd tank drive.

In fact anyone planning on going with skid steering will probably want to really look at using at least six wheels to minimize the amount of skidding required in a turn.

Jason

It may be even worse than it first appears. Unless you've already broken traction, skid steering has to overcome what could be as high as the static transverse friction (if you want to turn as you are starting out). At first glance it appears 6 wheel drive raised center is the way to go for skid steering (whether tank mode or joystick mode on the controls). Also the abnormally high differences between static and dynamic coefficients is probably worth a bit more analysis. In past years static vs. dynamic and inline versus transverse were relatively minor differences that could often be more or less ignored. Not so this year. Don't count on being able to control the bot until you do the math

[Raul]

Originally Posted by markulrich

...
Has anyone felt the new playing surface? How much does it cost? Would plane old hallway concrete be a suitable substitute?

We bought two 4' x 8' sheets of that "ice" material ($30 per sheet) for the floor and did some testing. We compared traction on the "ice" the carpet and plain old tiled floor. The ice was the slickest. The carpet was slick but not as bad. The tile was surprisingly almost the same as the ice. So, to answer your question, if you cannot afford to buy some of the ice material, use a tiled floor as your best simulation.

[gburlison]

Originally Posted by Raul

We bought two 4' x 8' sheets of that "ice" material ($30 per sheet) for the floor and did some testing. We compared traction on the "ice" the carpet and plain old tiled floor. The ice was the slickest. The carpet was slick but not as bad. The tile was surprisingly almost the same as the ice. So, to answer your question, if you cannot afford to buy some of the ice material, use a tiled floor as your best simulation.

Did you collect and numbers to help us compare?
I was thinking that we might stretch a large sheet of plastic over a tile floor and tape down the edges. If the plastic is thick enough, hopefully the robot will not wrinkle and tear it long enough to practice.

[sdcantrell56]

So does anyone want to chime in about using these wheels as omniwheels. Would it even be possible. I am feeling slightly lost since all of my preseason designs involved mega-traction and multi-speed high torque transmissions

[dtengineering]

Originally Posted by sdcantrell56

So does anyone want to chime in about using these wheels as omniwheels. Would it even be possible. I am feeling slightly lost since all of my preseason designs involved mega-traction and multi-speed high torque transmissions

Omniwheels are specifically designed to have a lower coefficient of friction in the transverse direction than in the inline direction.

These wheels, according to the manual, have a transverse coefficient of friction that is about twice that of the inline direction. They are, by my reading... anti-omni wheels.

Jason

[GaryVoshol]

Originally Posted by Raul

We bought two 4' x 8' sheets of that "ice" material ($30 per sheet) for the floor and did some testing. We compared traction on the "ice" the carpet and plain old tiled floor. The ice was the slickest. The carpet was slick but not as bad. The tile was surprisingly almost the same as the ice. So, to answer your question, if you cannot afford to buy some of the ice material, use a tiled floor as your best simulation.

Did you do any testing on terrazzo floors? (The stuff where a slurry is poured, and then polished after it hardens)