Propulsion that does not involve driving wheels

[Dominicano0519]

Originally Posted by GaryVoshol

You could take the robot outside and run it a few laps around the cement parking lot to scuff the wheels too. Just try to pass inspection after that.

man just pop those bad boys on after you pass inspection have some other tires on

[GaryVoshol]

Don't try that on my field - I'll have you reinspected.

[Dominicano0519]

Originally Posted by GaryVoshol

Don't try that on my field - I'll have you reinspected.

god you guys cant take a joke

my team is not competing this year so of course i won't try it, besides i was just kidding that would be against the spirit of the rule i mean its obvious that what im proposing is illegal

[Tottanka]

Originally Posted by Dominicano0519

god you guys cant take a joke

my team is not competing this year so of course i won't try it, besides i was just kidding that would be against the spirit of the rule i mean its obvious that what im proposing is illegal

A 'joke' stops being funny after 5 times.

[sdcantrell56]

Seriouslly... You have proposed numerable illegal and unethical measures to increase traction. It really isn't funny and appropriate after the 4th time. Although you might not be serious, what happens if a rookie sees this and thinks that this thinking is acceptable in FIRST?

[sxysweed]

Originally Posted by smurfgirl

I'd say the call is quite clear... this goes against the spirit of the rules, even if it is not explicitly forbidden in the letter of the rules.

But isn't the spirit of the compition innovation?

Originally Posted by chmp09

I don't think that you could use a fan as an effective defense. The shape of the game piece does not make it very resistant to air. Its also kinda heavy, not that heavy, but heavy enough to make it hard to stop.

Not necessarily a fan as everyone seems stuck on. But for those that have experience in RC Aircraft, the duct fans provide LOTS of pushing power. I'll have to try it out, but I think it could move the ball. Have them point at an angle upwards (posssibly 45*) and you should be able to blow the balls away if they are thrown. If they are otehrwise placed in, that's another story.

The 45* would also give some forward movement and traction, but how much and how useful it is, is uncertain. My question is (haven't read the rules yet), is it legal to deflect the balls like that?

[Ziaholic]

Originally Posted by EricH

For those of you saying that a downforce would be legal:

I'm 99% sure that it's not legal. The wording in the rule is clear: if it increases traction, it's not legal. The idea is to increase the normal force, which increases available frictional force (not friction), which increases traction. That's increasing traction, which is illegal.

The other 1% says to ask Q&A when it comes online and see what they say.

I've gotta' lean in this direction also. Very well put. Downward force does increase traction which would be illegal.

So while this vertical force is most likely not allowed, the arguement for horizontal forces is not as simple, unless you could argue that it's not perfectly horizontal ... a sneaky team might try to offset their swampboat's thruster to provide a small downforce.

I'm guessing that they'll refine the rules to include phrases that say that the wheels must be the locomotive force of the 'bot.

[hipsterjr]

This thread is way off topic. The main idea was to drive a robot with horizontal fans. Someone mentioned a vertical fan to increase traction and now everyone is arguing about that. IMHO a hybrid driven wheel and propulsion fan drive system is most defiantly legal and has some interesting advantages.

[martin417]

Originally Posted by EricH

For those of you saying that a downforce would be legal:

I'm 99% sure that it's not legal. The wording in the rule is clear: if it increases traction, it's not legal. The idea is to increase the normal force, which increases available frictional force (not friction), which increases traction. That's increasing traction, which is illegal.

The other 1% says to ask Q&A when it comes online and see what they say.

The way I read the rule:

<R06>"No other forms of traction devices (wheels, tracks, legs, or other devices intended to provide traction) are permitted

Increasing downforce does not provide traction. I know this is a semantics argument, but I think the rules are very carefully worded. Traction is provided by whatever contacts the ground. If it doesn't contact the ground, it cannot provide traction.

[Bongle]

I think the "fan as downforce" concept is fundamentally flawed, anyway.

So you take a fan producing x newtons.

-If pointed horizontally, it could accelerate or decelerate your robot to the tune of x newtons
-If pointed vertically, it generates x newtons of downforce, which increases the amount of friction you get by 0.05 * x (mu * normal force increase). This is far less useful than a horizontal fan.

[Kevin Sevcik]

I agree with Bongle that using a fans pushing down to increase downforce is a little silly. I don't think it's going to be illegal, however. The super strict readings of <R06> I'm seeing don't seem sensible to me. If you're saying the fan is illegal because it's increasing downforce and thus increasing traction.... Then wouldn't the entire robot be illegal because it's adding additional weight, increasing downforce, and adding traction? The rule specifically says that the intent is for there to be a "low-friction" dynamic. Not a "low-traction/pushing power" dynamic.

Anyways, back to the gyroscope, because I think it's brilliant, and I want someone to try it. I don't know that the appropriate way to use the gyro is as a stiff structure to turn against. It would certainly work, but the dynamics are going to be weird, and I don't know if it's the most efficient use of a gyroscope. Specifically about the dynamics, if you wind up the gyro to a good speed and then try to rotate against it, it's going to generate an overturning moment perpendicular to the axis of rotation of the gyro and the axis your robot is rotating about. Which is going to try to flip your robot front to back, side to side, or something, depending on the orientation of the gyro at any particular moment. (Cool, huh?)

I think the better, if more complicated, use would be as a control moment gyroscope. If you remember the old science trick with a spinny chair and a bicycle wheel, you've got the basic idea. Here's some videos to jog memories just in case:
Cornell Video
Honeywell Video

Using a control moment gyro is a little more complicated, as you'll need to keep track of the absolute angle of it, and try to keep it vertical, but the axis of rotation will always be the same relative to your robot's direction of travel, so the over-turning effects will be more predictable. It should really do a very good job of keeping you pointed in the proper direction. I'll have to do some math to work out just what sizes and speeds we'd be talking about to get a useful effect, but it's definitely something I'm seriously considering.

[feilmeier]

As I read through this post, I notice a number of discrepancies that alter some people's view points.

1) A rolling wheel has the same coefficient of friction as a static wheel, since as the wheel rolls, each part of the wheel stays in static alignment in respect to the piece of ground that it contacts. Therefore, the coefficient of friction provided by rolling, non-slipping wheels is .06.

2) By having a vertical fan pointing downwards, you simulate additional mass. This increases not traction, but weight. The mass of the robot stays the same, but the weight increases.

3) Unless your fans are a lot stronger than that I am imagining, the falloff for most air flow from the fans is quite sharp, reducing the potential for anyone being knocked over, or being hit by flying debris. Remember the inverse square law people.

Thanks for listening to me. As you can see, I just finished a section on friction in my physics class.

[EricH]

Originally Posted by feilmeier

2) By having a vertical fan pointing downwards, you simulate additional mass. This increases not traction, but weight. The mass of the robot stays the same, but the weight increases.


Thanks for listening to me. As you can see, I just finished a section on friction in my physics class.

Weight, when directed perpendicularly to a surface such as the ground, is also known as Normal Force for purposes of determining friction between an object and the surface. This increases the frictional force that is available, increasing the traction.

[professorX]

Originally Posted by dtengineering

Of course, once you've got the fans, you could also use them to suck air from underneath the robot to increase your traction.

Jason

I believe that you are not able to do this.

<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

[feilmeier]

Weight, when directed perpendicularly to a surface such as the ground, is also known as Normal Force for purposes of determining friction between an object and the surface. This increases the frictional force that is available, increasing the traction.

Indeed. I did not mention normal force, because of two reasons. By Newton's second law, F=MA. If you simulate an increase in mass without reducing the acceleration (ie. gravity), then of course you increase the normal force. The other reason is that weight is measured in Newtons, as is the normal force. The only difference between normal force and weight is if the object suppyling the normal force is incapable of holding the weight. If suddenly robots started falling through holes in the floor during the game, then we would have to revert back to using the term normal force. But for this case where we are certain that the floor will hold us up, the term weight is equally valid as the term normal force.

Since we also know that traction is commonly used to refer to static friction/adhesive friction as opposed to kinetic friction/sliding friction, by the very definition of Rule <R06>, to add any sort of metal to the wheels is to increase the traction of the device, and thereby banned. Come January 7th, let us ask the Q and A, and see if indeed this approach is acceptable.