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-   -   How can we drive on this new floor? (http://www.chiefdelphi.com/forums/showthread.php?t=71037)

kgzak 03-01-2009 18:46
Re: How can we drive on this new floor?
 
The fewer wheels you have will actually increase you traction because you will have more weight on the drive wheels we are thinking about having a front wheel drive with one more wheel in the back. We would use a tank drive to be able to turn with the trailer.

Racer26 03-01-2009 18:48
Re: How can we drive on this new floor?
 
Quote:
Originally Posted by gorrilla (Post 789942)
could you find this and link to it?
Quote:
Originally Posted by FRC 2009 Game Manual
<R06>
ROBOTs must use ROVER WHEELS (as supplied in the 2009 Kit Of Parts and/or their equivalent as provided by the supplying vendor) to provide traction between the ROBOT and the ARENA. Any number of ROVER WHEELS may be used. The ROVER WHEELS must be used in a “normal” orientation (i.e. with the tread of the wheel in contact with the ground, with the axis of rotation parallel to the ground and penetrating the wheel hub). No other forms of traction devices (wheels, tracks, legs, or other devices intended to provide traction) are permitted. The surface tread of the ROVER WHEELS may not be modified except through normal wear-and-tear. Specifically, the addition of cleats, studs, carved treads, alterations to the wheel profile, high-traction surface treatments, adhesive coatings, abrasive materials, and/or other attachments are prohibited. The intent of this rule is that the ROVER WHEELS be used in as close to their “out of the box” condition as possible, to provide the intended low-friction dynamic performance during the game
Seems to me it says nothing about requiring the wheels be oriented so MOTION is in the direction of the tread, only that they be mounted with tread touching the floor (i imagine to foil us lateral thinkers that might try to cantilever the wheels and use the flat face of them to try to move forward)

Sam2197 03-01-2009 18:49
Re: How can we drive on this new floor?
 
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

writchie 03-01-2009 18:54
Re: How can we drive on this new floor?
 
Quote:
Originally Posted by Thermal (Post 789927)
There is another rule stating that the wheel's rotation MUST BE inline with movement of the bot, so that the axle the wheel is on is perpendicular to the bot and wheels movement
If you are talking about R06 I don't read it that way. The tread must be in contact with the ground and the wheel axis must be parallel to the ground and through the wheel hub. However, this does not imply "inline. At first read, I do not see what rule would prohibit a crab steering configuration unless I missed something.

dtengineering 03-01-2009 19:00
Re: How can we drive on this new floor?
 
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

thefro526 03-01-2009 19:02
Re: How can we drive on this new floor?
 
I think the intention of R06 is to prevent teams from using the non-treaded portion of the wheel as a traction surface, not rule out Holonomic or Kiwi type drive systems.

cdfps 03-01-2009 19:05
Re: How can we drive on this new floor?
 
2j

thefro526 03-01-2009 19:12
Re: How can we drive on this new floor?
 
As I think more and more about this game I've come to a conclusion.

No matter what you do, you'll still be working with limited traction. Instead of worry about getting more traction, why not just embrace the lose of traction?

I think the question of "how can we drive on this new floor?" should be posed to the drivers. It'll require quite a bit of finesse and skill to master the lack of traction but those who do will be at a huge advantage.

Perhaps you should have your drivers research things like Drifting, ice driving, and driving in the rain to get some ideas. I personally, dabble in a bit of drifting myself so I'd like to see if I can apply that experience to driving a robot on this surface.

xitaqua 03-01-2009 19:13
Re: How can we drive on this new floor?
 
I think the solution for driving on this new floor will be more likely on Software : http://en.wikipedia.org/wiki/Traction_control_system.

Gotta think how does the algorithm work on a 4W drive vehicle works......

Cheers,
Marcos.

Sam2197 03-01-2009 19:18
Re: How can we drive on this new floor?
 
Quote:
Originally Posted by thefro526 (Post 790005)
As I think more and more about this game I've come to a conclusion.

No matter what you do, you'll still be working with limited traction. Instead of worry about getting more traction, why not just embrace the lose of traction?

I think the question of "how can we drive on this new floor?" should be posed to the drivers. It'll require quite a bit of finesse and skill to master the lack of traction but those who do will be at a huge advantage.

Perhaps you should have your drivers research things like Drifting, ice driving, and driving in the rain to get some ideas. I personally, dabble in a bit of drifting myself so I'd like to see if I can apply that experience to driving a robot on this surface.


i totally agree with that. theres no way to increase traction. and i also do some drifting myself. main thing is you cant give a lot of power right away. otherwise you will just spin your tires(wheels). it will require some skills by the drivers

writchie 03-01-2009 19:21
Re: How can we drive on this new floor?
 
Quote:
Originally Posted by dtengineering (Post 789982)
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 ;)

Branden Ghena 03-01-2009 19:23
Re: How can we drive on this new floor?
 
Quote:
Originally Posted by 1075guy (Post 789955)
Seems to me it says nothing about requiring the wheels be oriented so MOTION is in the direction of the tread, only that they be mounted with tread touching the floor (i imagine to foil us lateral thinkers that might try to cantilever the wheels and use the flat face of them to try to move forward)
Darn, the first thing I thought was that we should make a walker bot using the wheels sideways. :D

eNyoron 03-01-2009 19:43
Re: How can we drive on this new floor?
 
You can add more traction to the wheels by adding downward force onto the wheels. Any additional weight would be dispersed by the wheels regardless of where it's centered unless the robot has another point of contact with the ground (or if it goes all the way through the trailer). So you could add force with springs or with pneumatics, thereby adding traction.

But I'm wondering, could you propel yourself by say, pushing off of walls? There have got to be some ways to move outside of the traditional wheels on the ground that are still legal within the competition constraints.

robodude03 03-01-2009 19:44
Re: How can we drive on this new floor?
 
Quote:
Originally Posted by thefro526 (Post 790005)
As I think more and more about this game I've come to a conclusion.

No matter what you do, you'll still be working with limited traction. Instead of worry about getting more traction, why not just embrace the lose of traction?

I think the question of "how can we drive on this new floor?" should be posed to the drivers. It'll require quite a bit of finesse and skill to master the lack of traction but those who do will be at a huge advantage.

Perhaps you should have your drivers research things like Drifting, ice driving, and driving in the rain to get some ideas. I personally, dabble in a bit of drifting myself so I'd like to see if I can apply that experience to driving a robot on this surface.
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.

Zyck_titan 03-01-2009 19:47
Re: How can we drive on this new floor?
 
It seems to me that heavier Bots will do a lot better, and I'm sure everyone will be maxed out on weight, so the question is how do you add weight....without adding weight....;) *Hint hint Nudge nudge*


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