Re: Propulsion that does not involve driving wheels
 

Using a vacuum to create downforce, as long as nothing other than rover wheels are touching the ground should not be illegal or against the spirit of the rules. This would be an innovative solution as you would not be adding anything extra between the physical interaction of the ground and the robot, and as such would not be adding traction. Also the Cof is remaining the same no matter how much downward force is applied, the only thing changing is the normal force which is not friction.

Re: Propulsion that does not involve driving wheels
 

The biggest problem that arises with a slippery floor is the difficulty in precision maneuvering. Large fans or leaf blowers will allow for even less precision than the wheels, so it doesn't really solve anything (it would look cool, though). The only way to increase your stopping distance, turning radius, etc. is to increase your normal force without increasing your mass, as the post above describes. Other than that, your pretty much stuck with the oil slick.

Re: Propulsion that does not involve driving wheels
 

Assuming traction and friction to be synonyms, then anything designed to increase normal force is illegal. Friction is the product of the coefficient of friction and the normal force, so increasing either coefficient of friction (explicitly prohibited by wheel requirements) or increasing normal force will increase traction, which is in violation of R06.

Re: Propulsion that does not involve driving wheels
 

The rule specifically describes ways to change the coefficient of friction like putting rubber on the tires, not changing the normal force. Coefficient of friction is different than friction.

Besides, the only way I can think to change normal force without changing mass is a large fan, which would be impractical and be more pain than its worth.

Re: Propulsion that does not involve driving wheels
 

hey you can always wear the wheels in such a pattern that it would be really rough and grippy or ad a chemical that would do that


and for propulsion

i have three words pneumatic rocket boosters

Re: Propulsion that does not involve driving wheels
 

Another way to increase the normal force: give yourself a nice hydraulic suspension and bounce your way along like an El Camino down the strip -- at the lowest part of the bounce you'll have increased the normal force and can apply more power to the wheels at that time (assuming you don't want your wheels to spin out). Of course, at the top-side of the bounce you've a smaller F_n and can apply less power.

If you don't like how that affects your shooting/tracking/&c., mount ballast (or your batteries, or your control system) on a piston inside your robot and wiggle that up and down to the same effect.

An idea that came over from another thread: an imbalanced two-wheel design. If CoG is forward of wheels so that the trailer (through the hitch) is effectively holding down the back of the robot, then you'll have a higher F_n than solely due to robot weight.

Re: Propulsion that does not involve driving wheels
 

You might want to go read <R06> more carefully.
Translation: Your proposed method for more traction is illegal.

Re: Propulsion that does not involve driving wheels
 

Have you considered the safety factor of having a fan powerful enough to propel a ~150 pound robot faster than the wheels can? That's going to be quite a lot of wind. Considering that people are usually standing pretty close to the arena, I could easily imagine someone who is already off balance being pushed over and getting hurt by that. Same with light, unsecured equipment, or maybe tablecloths, barriers, etc. that can easily be blown up or away. And that's ignoring the damage that smaller things kicked up by the fan, or even worse, accidentally fed into the fan could do. It's not something I'd want to risk betting on at this point, lest it violate <S01>. I would wait until the Q&A clears things up.

Not to mention, I doubt that the crowd will appreciate being blown upon. Just a thought.

Re: Propulsion that does not involve driving wheels
 

no im saying those wheels have a concave surface so you make you grind out as much of it as you can

Re: Propulsion that does not involve driving wheels
 

yeah with all that force newton says that the robot behind that wind is gonna be pushed around and if you get two or three in a match you wont be able to do anything

Re: Propulsion that does not involve driving wheels
 

Umm... Excuse me? Re-read the bold portion of the rule in my last post. There should be something about altering the surface profile. Grinding down the surface is doing just that.

Re: Propulsion that does not involve driving wheels
 

no grinding is one thing practicing all everyday with that set of wheels for three weeks is another thing im just saying use the most worn out set of wheels that you have it will give you an edge

Re: Propulsion that does not involve driving wheels
 

Our team did some tests to see if a leaf blower could deflect an incoming cell, but we had very little success even though the leafblower was significantly stronger than any fan that a 12V CIM could power. The design of the balls just doesn't have enough surface area for them to be affected by air movement.

Too bad.

Re: Propulsion that does not involve driving wheels
 

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.

Re: Propulsion that does not involve driving wheels
 

Using the said fan idea is nice, but you would need a skirt to keep an air pillow between the robot and the ground, and to contain the air. This is how current hovercrafts work, and it would provide you with good steering, and manuveurablity, but horrible friction one bump and you would go flying seeing as you have nearly no contact with the ground. Not to mention that you will have trouble picking up balls off the ground, and your skirt will need to be lower then the bumper zone so you can have regulation bumpers.