Vacuum
 

I know its legal to charge the pneumatic system prior to the match, but is it legal to create a vacuum or suction and store it in a tank prior to a match?

(We would plan on using the venturi generator from last years KoP)

Re: Vacuum
 

I think it would be very hard to do that. Also, is the venturi even legal this year?

Re: Vacuum
 

Thats what I was wondering...

Re: Vacuum
 

Yes, the venturi generators from last year are legal as per Rule <R87>. However, they don't work in such a way that you could "pre-charge" a tank, when you open a solenoid valve letting air through them they create the vacuum, rather than having a "vacuum tank". In addition, those things are serious on the air usage, so if your going to use them for extended periods of time, you need the compressor on-board.

--NOTE-- We used them last year to pick up the tubes, worked pretty well, but the skin of that ball is going to be much harder to use vacuum cups on.

Re: Vacuum
 

Still allowed... <R87>

For the purposes of the FIRST competition, a device that creates a vacuum is not considered to be a pneumatic device and is allowed. This includes, but is not limited to, venturi-type vacuum generators and off-the-shelf vacuum devices (as long as they are powered by provided or permitted motors).

Re: Vacuum
 

I'd like to see one with only one point of contact on a Trackball that actually would work. I don't think it will.

The reason I say this, is because the fabric outer covering of the Trackballs will not result in a very good seal as the nice one layer vinyl tube would last year.

If you tried this, you would probably need 2 or more on quite opposite sides of a ball, and in that case, why even bother adding the venturi mechanism when you basically have a gripper with 2 points of contact anyways?

Re: Vacuum
 

Kind of what I was thinking...

Re: Vacuum
 

Vacuum can be used for many things besides picking things up.

If you can figure out a way to store vacuum in a sealed tank (think solenoid valves) and prevent the vacuum from 'leaking' out through the venturi (think timing of air supply), then yes, you should be able to store vacuum prior to a match, by "charging" the tank in the pits, sealing it up.

Of course, this is merely my opinion, I cant say if it is legal or not, but this has been done by teams last year.

Don

Re: Vacuum
 

thanks, thats what I thought, just trying to convince a mentor that it won't work...

Re: Vacuum
 

We did this in 2004 the only year it was technically legal. Note the solenoid use rule, R60, and the above quoted R87:
A vacuum is not a pnuematic system.
The solenoid rule clearly states that you can only use solenoid valves for pnuematics.
Vacuum is not equal to pnuematics therefore solenoid valves used to contain the vacuum are not allowed.

Re: Vacuum
 

Is a shop vac legal as a vacuum source?

Re: Vacuum
 

A Shop Vac contains a motor that is not FRC legal. If you can power it with an FRC legal motor the other parts of the Shop Vac are certainly allowed.

Re: Vacuum
 

One thing to keep in mind with vacuum is that the forces you can create are rather limited unless you have little leakage or very high vacuum generating capacity. Recall that a perfect vacuum is by definition -1 atm relative to ambient pressure, which is approximately 14.7 psi, so to exert a lot of force, you need a lot of area, which in the real world usually means you have a lot of leaks. Assuming your vacuum storage tank and evacuation system are legal (I haven't looked into that aspect), you would probably need a pretty large tank if you plan to grip a leak-prone surface like the Trackball.

Re: Vacuum
 

No comment on the legality of it ... but technically it'd be a challenge to convince me that it's worth the effort. We tossed that idea around for a little while during our brainstorming sessions, but it died off somewhat quickly.

For ball handling, with it's somewhat porous cover, the volume of air that you'd have to move would be huuuuge ... and the area of the suction cup would have to be pretty large. I don't think that a tank behind a solenoid would do the trick. I'd wager that you'd have to be constantly sucking large volumes of air to maintain a partial vacuum at the cup

If it's not for ball handling, then it's hard to comment on it's feasability. I suppose that there could be some use for a (partial) vacuum, but aside from ball handling, nothing comes to mind at the moment. ... other than an idea for next year's competition ... can anybody say Roomba-bots? Next year's trackballs could be dime-sized, and we'd have to gather as many as possible.
The regional winners get to travel to Mr. Kamen's house to help with his spring cleaning! :rolleyes:

Re: Vacuum
 

I'd venture that not only is that not clear, it's most likely wrong.
<R60> prohibits the use of electric solenoids, meaning electromagnetically controlled linear actuators. It notes that pneumatic solenoid valves, such as the ones found in the KoP, are legal. It makes no mention as to restrictions of their application... as such, you can use them in your pneumatics, you can use them as part of your end effector, you can use them as ballast, you can use them as non-functional decorations, and if you can make it work, you can most certainly use them to control a vacuum.

Re: Vacuum
 

I will again point out that the rule quite clearly states that vacuum is not considered pnuematics. Therefore you would be using the solenoid for a purpose other than pnuematic. I think this is quite clear.

Also you want to use vacuum solenoids not pnuematic.

Re: Vacuum
 

The next thing on the valves is the pilot control of a valve. valves require a air pressure to work. Just keep that in mind. Dont use a venturi! It is not enough use a bima cylinder on a fisher price motor. the rest you will have to figure out.

Has anyone tried to use a vacume on the nylon cover? Tell the success or failure, please. I am not sure how much leakage there must be to over come in volume.

Re: Vacuum
 

Peter, <R60> only talks about what parts are allowed to be on the robot. It says nothing about how they are allowed to be used. Whether the solenoids we are allowed to use will physically work for this application is up for debate, but please don't spread misinformation when the rules say something else.

Re: Vacuum
 

I am not spreading mis-information. We clearly disagree on the interpretation of the way this is written and both feel strongly that the way it is written agrees with our case. As such anyone who wants do this should directly ask about it through the FIRST Q&A system.

Re: Vacuum
 

As it turns out, you are.

The rule you are quoting, <R60>, is forbidding electric solenoid actuators. It's not saying anything about legal or illegal ways to use pneumatic solenoid valves. Ironically, the parenthetical comment that is intended to clarify the meaning is apparently what's leading you to misinterpret it.

Do you know what electric solenoid actuators are? They're the sort of thing that you find in chime doorbells, where an electric current causes a magnetic field to move a metal rod.

Re: Vacuum
 

Worth the effort? Challenge?

OK, some basic physics here. The ball is 40 inches in diameter. it is a sphere. So, you contact that sphere with a large circular hole (a box with a hole maybe?) behind which you have a vacuum source. Yes there will be leakage, so a centrifugal fan is in order (maybe a vacuum cleaner with the AC motor replaced with KOP motors?) If your circle is, say around 20" in diameter, that will give you an area of more than 300 square inches. With a delta P of 1 PSI, (Delta P is the difference in pressure, so 1 PSI of vacuum) that will give you 300 LB.s of holding force. Even a modest shop vac can create almost 2 PSI of vacuum, and a huge flow rate (relatively speaking) so any leakage around the rim is not even noticeable.

Not only is it doable, and worth the effort, look for it at a regional near you!!!:D

Re: Vacuum
 

While this is slightly different from storing a vaccuum in a tank before a match, it certainly ends any debate on whether a vacuum gripper will work.

http://www.chiefdelphi.com/forums/sh...ad.php?t=63732

Jason