Floor wearing away
 

I was doing some traction tests with a stationary robot (measuring the pull of the robot at different drive speeds). I noticed about halfway through that there was a smell of urine with a hint of burning plastic. Upon closer inspection, I found the regalith to be wearing away, leaving small piles of dust. It had by no means worn flat, but the fact that the floor wears away before the wheels worries me for two reasons:
1. Regalith is a fiberglass composite. That effectively means it leaves fiberglass dust when it wears away. I handle fiberglass almost as carefully as I handle asbestos (that is, not at all, whenever possible).
2. At the arena, the robots all start in approximately the same position. If a majority of the robots start by spinning out as fast as possible to gain the most traction, these starting positions will soon have small piles of dust there, affecting both the air quality and the traction (or lack thereof).


I was finding that, as I sped up the drivetrain, the traction oscillated between 10lbs and an increasingly higher pull (20lbs when I stopped). I hypothesize that if the floor did not wear, then the traction would have remained at a little less than 10lbs, however, I have neither the funds nor approval for continued destructive testing.

Re: Floor wearing away
 

That's interesting. I'm sure FIRST must have tested this before. Maybe they add something that doesn't affect the coefficient of friction but reserves the playing field's condition

Re: Floor wearing away
 

:) Greatest traction is achieved when starting out by applying torque to the point just before wheel slip (Dynamic vs. Static Friction). If you are burning out at start, you are not going anywhere if the surface is intact. I suspect your traction increase may be due to the material the rogolith is adhered to is being worn through. It may have a higher CoF than the surface film. FIRST may have to clean these areas between matches, and may even have to replace sheets in these areas if it truly is a problem. It will be something to watch for while we are testing, and report to FIRST as a potential problem. Everyone should take note, and Thanks or the observation. :ahh:

Re: Floor wearing away
 

These spots will be very hard to replace individually because the official playing fields are made of three 8 X 50 foot rolls of this material and not individual sheets that we are using.

this could be a problem... I am not as worried about the damage to the field as much as I am worried about the potential of fiberglass dust to be in the air around the fields...

I would not think it would be very much...but it does not take much.

Re: Floor wearing away
 

Hey, we just did our first test woth the robot today, we put some weight on to make about 120 lbs, and we found dust on the wheels. I think the wheels were picking up the dust created by the floor. And we also found that the dust that stuck to the wheels, and greatly decreased the traction.

Re: Floor wearing away
 

No one's worried about the urine smell he described?... I can take dust, i can take a worn out launch area....I'm sick of urine...... don't ask

Re: Floor wearing away
 

Some links for FIRST Safety to peruse from the CDC:

http://www.cdc.gov/elcosh/docs/d0200...7/d000257.html

Does anyone have an MSDS for the regolith?

Re: Floor wearing away
 

Dust from wear is probably the biggest reason to not allow
vacuum effect robots, as these would suck the dust from the
floor and pump it into the air. It may be a good idea for the
field to be equipped with a HEPA vacuum, or some other dust
collector, to clean the plastic surface when needed.

Eugene

Re: Floor wearing away
 

Wasn't regolith a gel coated frp? Maybe the gel is to stop that?

Re: Floor wearing away
 

Totally agree...I'm kind of surprised that they wouldn't mention their special "mixture" (giving them the benefit of the doubt)

Re: Floor wearing away
 

Marshal:

You are not alone with your concerns and results. We experienced that same thing the first time we tested the robot. We immediately stopped when we started to smell the burning plastic.

Houston we have a problem.

To make matters worst, I'm fearful of using our hallways or gym. Any sharp turning or spinning and the robot leaves marks in the wax finish. I can not afford to make enemies with the custodial staff. :ahh:

We went out and sacrificed another $150 in FRP in an attempt spread out the damage and safety risk :mad:

Anyone have any idea what to do with this material after the season?

Re: Floor wearing away
 

This is why you keep some extra snacks and soda around to give to the janitors. Bribing them can't hurt ;)

Re: Floor wearing away
 

Are you sure the powder isn't coming off the wheels? We did a weighted test this weekend in our gym and noticed that for the one drive we did with weight on the bot, it left big white streaks across the tan/brown gym floor. When we wiped the streak, we were left with very fine white powder, leaving us to conclude it was the wheels, and not the gym floor, that was the source.

Re: Floor wearing away
 

Attached is the only one I had found, from a supplier's website.

http://www.sbs-frp.com/products.htm

Re: Floor wearing away
 

The only markings left on our Regolith after testing (particularly the sideways push) were black marks. The black marks won't come off and I believe are the wear of the field. I noticed the wheels themselves had some scratches them, and had a fine powder of something on them. I cleaned them before I investigated it.

Re: Floor wearing away
 

$15 at Home Depot:



Really, just get a "team-owned" mop. If practice sessions leave any marks on the floor, clean them up yourselves and don't leave them behind for the janitorial staff. You will make friends with them, they will appreciate it, and everything should be cool. The staff at our school have been wonderful. We got them involved many years ago with what we were doing. We let them drive the robot around and promised to always clean up our messes before they would ever have to. Ever since then, they have been very accommodating of us.

-dave



.

Re: Floor wearing away
 

...and it helps to feed them anytime your team hosts a pasta dinner for a fund raiser like we do. Or leave them the left over donuts......like THAT is ever gonna happen!!

Re: Floor wearing away
 

where did you get this information? On the field at the kickoff these sheets were exactly the same 4X8 sheets we can buy.....they were held together with what looked like a white masking tape.

Re: Floor wearing away
 

Re: Floor wearing away
 

The gel would wear for a while before you get down to the fiberglass. Probably the texture is mostly or all gel, and the backing is fiberglass. You could carefully sand a corner of the sheet and find out quickly. It can't be any worse than working on a Corvette! (ugh)

Re: Floor wearing away
 

Oh, c'mon now Dave, we can get a little more high-tech than that.
I won't mention the Scooba since that is the obvious choice, so instead I'll default to mentioning this little 'bot!
http://www.engadget.com/2005/12/01/t...7-swiffer-bot/


Or you can always buy a Swiffer, & hear the song "baby come back" playing in the background while your old mop looks on. :p

Re: Floor wearing away
 

That sounds an awful lot like appreciating them.

Janitors are among those important behind-the-scenes people who help keep things running smoothly. It never hurts to say thank you, that's for sure.

edit: ah, after reading the rest of the thread, I see I'm in excellent company in praise of the janitors. :)
Rock on.

Re: Floor wearing away
 

gel coats are only about 25 mils thick... it wont take long to wear through that in the same spots over and over again.

I worked on gel coats for a year. We used the same polyester resin as the composite material for both the fiber glass substrate and the gel coat. The only difference is that gel coats usually have an additive to increase resistance to UV or water, and they usually have a nice color pigment added, in this case a snow white. Otherwise, polyester resin is a yellowish translucent material.

Polyester is cross-linked with styrene molecules, which are benzene rings. When the polyester burns or is ground in to fine particulate, the aromatic groups go airborne, giving off a pungent 'urine' smell as described. The MSDS for the Glasliner FRP leaves the field "carcinogenic" blank. Frankly they don't know if it is dangerous in such small quantities of dust. Likely not, but the MSDS is not complete yet.

There's your daily dose of materials science.

Re: Floor wearing away
 

Sorry I misread the MSDS, the toxicology report was negative, but it still recommends wearing a mask when there is particulate present.

Styrene is noticeable in ppm quantities, so while the smell is not a good sign, it won't harm anyone in limited exposure. If you find yourself in contact with a lot of dust, it might be a good idea to wear a mask:)

I also forgot to mention that I spoke with a polymers expert yesterday, he said pretty much the same thing, small quantities aren't too much of a problem, wear a mask if it bothers.

Re: Floor wearing away
 

Did you work with textured materials, or smooth?

Re: Floor wearing away
 

Actually I doubt it... they will probably repair it like they repaired damaged holes in the carpet... with tape! They mentioned a fiberglass tape that they would secure the sheets together with, my guess is since they feel it is good enough for that, they can use it to patch any damage to the regolith and not have to roll out new sheets. Depending on the wear, they might have to replace the sheets daily, but I doubt they would ever stop a competition for it, just throw some fiberglass tape on there.

Re: Floor wearing away
 

Yupp I noticed this problem as soon as we started driving on the stuff. I've gotten figerglass in my hands multiple times already. It hurts pretty bad :ahh: , not to mention the smell...and breathing it in. The main concern of FIRST will probably be the large amounts of people breathing in fiberglass dust. That CAN NOT be good.

Re: Floor wearing away
 

Smooth coatings, not sure how they made the texture. From my experience, the gel coats I made were spray on coatings, meaning the texture wouldn't cause too much variation on the thickness of the coating, but who knows... maybe they were blade cast and then a texture was applied. Though I think that is unlikely since that layer would have to be several mm thick.

I don't know if you were just curious or if you were trying to make a point of it, but good point anyway, heh. There is no information on the gel coat they use unfortunately =(

Re: Floor wearing away
 

I was just curious, because it's possible that there is quite a difference if they make the panels with a different process than you are familiar with. I suggested sanding the texture off a corner of a sheet of FRP as a way to see how thick the gel coat is....I"m trying to be helpful!

We need to buy some soon, maybe we can figure it out. We also have experience with fiberglass on our robots, the chassis the past 3 years were made of pultruded structural fiberlass.