Can someone verify that I am correct that I am not reading any pneumatic rules that prohibit the number of storage tanks or the number of cylinders and stroke length et cetera other than limits based upon BOM and COTS price limits?
Having been at this since 2001, I recall strict limits in the distant past of max four storage tanks and four or five cylinders with stroke length limits of 24 inches.
I’ve read the pneumatic rules section of the robot rules as well as the 2013 FRC pneumatic handbook. I’m just not seeing restrictions/limits so please point them out to me with a reference page or the like if you see them.
As far as I remember, that is basically how it was last year, whatever tanks you want as long as you are under weight. Haven’t actually read that section of the rules too closely yet, but it sounds like it hasn’t changed.
There have been no limits since 2011, before then we were limited to 2" bore and 24" stroke for cylinders and could only use a limited number of tanks identical to those supplied in the KOP
Consider that the tanks were supposed to be filled by the competition battery each match, and that tanks do not fill instantaneously (some teams took 7+ minutes to fill). This may not seem like a big deal, but it’s definitely something to panic about when you’ve just let the air out and you have 5 minutes to be on the field.
How many uses can you get out of a piston? Is there a calculation one can use to figure out how much air pressure/ volume the robot would need to actuate the piston X number of times?
I’m not sure that there is a rule about this. Last year we would fill ours in the the pit pre-match to ensure we had enough to deploy our appendage (see http://youtu.be/g_7ljqbIdi8 if you don’t know what I’m talking about) at the beginning of the match
Compressed air on the ROBOT must be provided by one and only one compressor. Compressor specifications may not exceed nominal 12VDC, 1.05 cfm flow rate. Off-board compressors must be controlled and powered by the ROBOT.
The intent of this rule is to permit teams to take advantage of the weight savings associated with keeping the compressor off-board. However, using the compressor off-board of the ROBOT does NOT permit non-compliance with any other applicable rules.
The compressor may be mounted on the ROBOT, or it may be left off the ROBOT and used to pre-charge compressed air in storage tanks on the ROBOT prior to bringing the ROBOT onto the FIELD.
They obviously wouldn’t notice if you charged your tanks with a big compressor in your pit prior to leaving to the field, and I’m sure some teams probably do it that way anyway, but there’s the rule regardless. I’m actually glad this was brought up, I wasn’t aware of this rule either.
There was a big issue last year at one of the regionals where a team was using a shop compressor in the pits to recharge their tanks in between elimination rounds. This potentially allowed them to recharge their tanks faster than otherwise would have been possible for teams following rule R80.
This caused a bit of an uproar here on CD, which makes me believe regionals will be looking more closely at teams with such compressors in their pits this year to make sure they are following the rules.
In the even-more-distant-past, the 2000 KOP contained a 1.5 gal[sub]U.S.[/sub] air tank, and the 1999 KOP had some sort of long, thin air reservoir. But you’re right: for several years, only 4 or fewer Clippard AVT-32-16s were allowed.
This year, there are no air volume limits (other than presumably the robot volume limits…).
I still hate this rule. It’s trivial to exploit (legally, via spare1 batteries, compressors, tanks and fittings), and adds negative value to the system (same inherent safety hazards, but with more points of failure exposed by repeated connections and disconnections).
FIRST should allow teams to draw pre-charge air from any appropriately regulated device connected to the robot’s on-board high-pressure pneumatic circuit (mandated to contain an overpressure relief valve and be constructed of appropriately rated components). But they don’t.
1 Spares aren’t defined this year. But presumably they’re allowed, and not subject to the module rule. Because if not, all hell breaks loose.
To clarify,
The restrictions were removed by the GDC in 2012 to allow teams more leeway in their pneumatic designs. The restricting factor is the 1/8" fittings and 0.32cV rules. Inspected for these devices, there should be no serious issues. Large cylinders cannot be moved with any sufficient speed due to the restrictions in volume/air flow.
The pneumatic rules are written such that a single KOP (or equivalent) **1.05 CFM **compressor can be used either on board or off board the robot to pressurize storage on the robot. This compressor (either on board or off board) can only be powered by the robot battery under control of the robot Crio and under software control to automatically shut off when the pressure switch is satisfied.
**If officials suspect that a robot has been pre-charged **with the use of a compressor other than as described above, they can release it’s pressure. There are several other remedies in place up to and including disabling, yellow card and red card. Think that a team that uses a method other than that described above is actually taking the field with a robot that has not passed inspection. Check the rules regarding fielding a non-inspected robot for further details.
The rules require the compressor be powered & controlled by the robot. Rule very clear & specific. Nothing in the rules require the air storage tank to be discharged between matches or the battery used to recharge the tank be the same that is used in the match.
“Last year, we were charging our robot’s air tanks, then swapping the battery before we went out on the field. It never occurred to me that this might not be entirely within the intent of the rules, and I guess I just assumed that all other teams were doing this as well.”
I believe at this time that we interpreted the rule correctly and are in compliance with common and game-legal practice.
There was a time (when pneumatics were first allowed) that teams could only charge the tanks when the robot was on the field and enabled.
Personally, I find it a little unsafe to charge pneumatics in the queue and would prefer that teams wait until the last minute to pre-charge. However, I understand the need to keep field reset times to a minimum.
There was something about a Q&A post in 2011 that implied a “competition-only” battery, and I wasn’t the only one who got that impression. Hence the ‘were’ in my statement. I didn’t pay attention to 2012 pneumatic Q&A since we didn’t use pneumatics last year.
My point is that planning and depending upon a large quantity of air is just as bad planning and depending solely upon a constantly-stressed battery. There’s no free lunch here. All it takes is for a question similar to the one from 2011 to be asked, and receive a similar response, for the whole design to go up in magic smoke.