Re: Pneumatic Restrictions & Improvments
 

Then this needs to be communicated to ALL LRIs. That rule was cited (in an incredibly rude manner) by the LRI at one of our events as the reason to remove a secondary compressor we used to power tools. He ignored any proof that we couldn't even connect the compressor to the robot (didn't have proper fittings) and was utterly unable to provide any clarification on the rule when asked. He also seemed to think that any spares we had needed to be outside the venue.

Re: Pneumatic Restrictions & Improvments
 

Andrew,
Sorry for the demeanor of the LRI at your event. We often ask teams to remove shop compressors for several reasons. One being the possibility of filling robot tanks, one being the extreme current drawn during startup. At some events this enough to take four pits or more off line.

Re: Pneumatic Restrictions & Improvments
 

Yes, another RI was kind enough to clarify that at the event.

For my own knowledge, in case this happens again, is there any recourse should a team feel that the LRI is being unreasonable? It was STRONGLY hinted by him that any further questions to him would be met with negative repercussions.

Re: Pneumatic Restrictions & Improvments
 

Although I acknowledge that FIRST can and probably should define constraints to level the playing field, it would be preferable that those constraints be defined in ways that make that intent obvious, while simultaneously being easy to understand and enforce.

That usually implies employing a straightforward restriction in place of a convoluted one. If FIRST really intends that the choice of compressor be used as a proxy for a limit on pneumatic performance (because the set of known legal compressors has a certain range of airflow, electrical and thermal characteristics), they should say so via an official channel. They should also endeavour to show that the restriction produces parity—with all the uncertainty in application of the rule, particularly off the field, this is hardly the case right know.

Or even better, if their objective is only to limit the on-field performance of the robot, rather than curtail off-field maintainability, they should write a specification that is permissive off the field, and restrictive on the field—like orifice size and pressure limits within the robot,¹ rather than worrying where the air comes from.

Incidentally, apart from (arguably) being an arbitrary part of the challenge, is there a legitimate reason to limit the ability of a team to recharge from any safe air source (provided sufficient controls on pressure and flow are present on the robot)? FIRST should permit teams to recharge their pneumatic reservoirs from any regulated (e.g. to 120 lb/in²), gauged, room-temperature air or inert gas sources that are safe and legal to carry into and operate within the venue.

¹ C_v is not an adequate way to specify this.

Re: Pneumatic Restrictions & Improvments
 

Andrew,
The LRI should be reasonable and non-threatening. You can ask him/her to check with the FTA and Head Ref at your event for a clarification/consult. While I have asked teams to remove compressors at most events I attend, on occasion the team displays a distinct need for a particular tool that requires the air. Following a discussion with the team to refrain from using the compressor except when absolutely necessary, the event staff and LRI were able to come to an understanding. If the use tripped a breaker, of course all bets are off. There are always extenuating circumstances to any decision and that may have been the case at your event. An offender may have forced the issue and required all compressors to be removed before they would remove theirs. Yes, it happens. There are (rarely) mentors who are not willing to act with decorum or GP that make things unpleasant for all.

Re: Pneumatic Restrictions & Improvments
 

Tristan,
While discussed, ad nauseum, in other fori let me copy it again here from paragraph 2 & 3 of Section 4, Robot Rules...
The rules listed below explicitly address what and how parts and materials may be used on a 2014 FRC
ROBOT. There are many reasons for the structure of the rules, including safety, reliability, parity, creation of
a reasonable design challenge, adherence to professional standards, impact on the competition, compatibility
with the Kit of Parts (the collection of items listed on any Kit of Parts Checklist, has been distributed via FIRST®
Choice, or obtained via a Product Donation Voucher (PDV), KOP), etc. When reading these rules, please use
technical common sense (engineering thinking) rather than “lawyering” the interpretation and splitting hairs
over the precise wording in an attempt to find loopholes. Try to understand the reasoning behind a rule.
In addition, another intent of these rules is to have all energy sources and active actuation systems on the
ROBOT (e.g. batteries, compressors, motors, servos, cylinders, and their controllers) drawn from a
well-defined set of options. This is to ensure that all Teams have access to the same actuation resources,
and to ensure that the Inspectors are able to accurately assess the legality of a given part.

Re: Pneumatic Restrictions & Improvments
 

That statement concerns the rules collectively, and I am of course aware of it. But absent clear evidence, it is illogical to believe that just because some rules are specifically intended to limit the energy sources and actuation options, that all rules are intended to limit those things, or that such intent is the primary motivation behind a particular rule.

To the greatest extent practicable, teams and officials should not be forced to speculate about the reasons for a particular constraint, as is clearly being done in this discussion. FIRST can easily make use of the blue boxes, or communicate through other channels, to alleviate that uncertainty.

Re: Pneumatic Restrictions & Improvments
 

Tristan,
You posted...
I merely showed you where First has done just that.

Re: Pneumatic Restrictions & Improvments
 

One....is the loneliest number that you'll ever do...Two....., can be as bad as one, it's the loneliest number since the number one...Aaaaaaa.
____________________
I cannot for the life of me understand how anyone can possibly misconstrue that particular rule as stated ".....One and ONLY ONE, Compressor may be used..." without some real out of bounds lawyering of the rule.

Of course spares (uninstalled of course), are allowed as "replacements" only....Not pre-installed in an onboard or off board compressor situation.

2 installed in an off board charging setup (pre-inspected or not), would be the exact same result, as 1 installed on board and 1 off board the robot would it not? As both still use 2 in the setup, whether actually plugged in or not at any time. (We have plenty of the older larger/heavier compressors sitting around....We cannot use them as belly pan mounted ballast though right...even if not plugged in and not plumbed, but properly and securely mounted? OF COURSE NOT, is the proper answer!)

And IMHO, both situations would violate the basic rule of only 1 compressor installed. (And the entire setup needs to be weighed as an integral part of the robot, and be completely powered by the robot and it's 1 also allowed battery, correct?)

If more than 1 installed and (possibly), working compressor (on board or off board is allowed), then 2 batteries installed on the robot would be OK also as long "as only 1 is plugged in or connected at a time." Do you see where this is leading?

Intentional "lawyerly" or not, violation of rules is usually referred to as "cheating" in most books, as it gives an unfair advantage to those that are following the rules.
_____________________
The above was directed at anyone arguing the easy as pie ONLY 1 Compressor Rule....Not any one party in particular. I am attempting to understand the argument as well as the next guy. Maybe I just misconstrued the meaning of "USING ONLY ONE COMPRESSOR." Or others have.

BTW, one of those big 12 Volt Muffin fans cool that compressor very well.

Re: Pneumatic Restrictions & Improvments
 

It is written in a way that means you must always use the same compressor to fill your robot. This is not practical, nor is it the intended meaning, as teams may need a spare.

Before you start attacking and calling people cheaters, I'd like you to show me a post where somebody argues that they can legally use two compressors at the same time.

Wrong. You'd better read up on what "one and only one" means. It means the same compressor must always be used. If that compressor breaks, you cannot fill your robot anymore. Obviously this makes no sense, so this is why we're having this discussion.

Wrong again! The one and only one compressor refers to compressors providing compressed air.
Please read the manual.

Re: Pneumatic Restrictions & Improvments
 

You should reread rule 79
It doesn't restrict anyone from having more than one compressor just only one that compresses air for the robot.

And this was also clarified this year through the Q/A question #209

Re: Pneumatic Restrictions & Improvments
 

Good job pointing out the importance of using/reading the Q and A each season, Roger! We always have one kid and one adult check almost daily/submit to Q and A as needed to ensure we are compliant throughout the build and competitions. Too painful to rebuild or change things at critical times as a result of not knowing what is or isn't legal...

Re: Pneumatic Restrictions & Improvments
 

Magnets,
CGL has stated what the correct interpretation of the rules as written. One compressor is practical as demonstrated by the over whelming number of teams that follow the rule of "one and only one". Spares are allowed as are spare motors of the same type and any item listed on the BOM. If this was not the case then many teams would be exceeding the BOM limit for spending on the robot. Your interpretation of additional compressors being used as ballast appears to be correct though provided the GDC/Q&A agree with you. I suspect their decision may be influenced by the same reasoning that additional CIM motors cannot be used as ballast if they exceed the max number allowed.

Re: Pneumatic Restrictions & Improvments
 

Many mechanisms we've seen over the years could have been dangerous, but if a team is smart enough to design that mechanism, they're probably smart enough to handle it safely. I think that the pneumatics are so limited both out of safety, and so that their power doesn't far exceed the power of other FIRST components.

Why not just enable your robot for a little while in the pits and let the compressor run?

Re: Pneumatic Restrictions & Improvments
 

One main reason is the ability to get the accumulator tanks all the way up to the max allowable storage pressure. This will never be achieved using the control system as intended because the pressure sensor turns the compressor off at a lower then max pressure.

In all honest I see no reason why a team should not be allowed to pre-charge with a separate compressor as long as that separate compressor is within the limits of the rules.

I would think the original intent of the rule was so that teams would not use multiple compressors while on the field.

Everything is a trade off, and as huge fan of pneumatic use in FRC I have enjoyed the recent changes and look forward to more relaxed rules that still allow us to operate in a safe and creative manner.