Is it still legal to have a pneumatics system with no compressor, just air tanks mounted on the robot?


#41

That only works if you’re powering your compressor via a relay. If you’re like most teams, who power their compressor via the same PCM as their solenoids, pulling the PCM breaker will also disable the solenoids. If that PCM is plugged into the PCM port on the PDP, pulling the special non-resetting breaker will also disable the VRM plugged in next to it.


#42

And that’s one major benefit to wiring the compressor individually. You’d also be able to still use your pneumatics if you didn’t pull the breaker for the compressor, and the compressor caused the breaker to trip, if the PCM and solenoids were wired separately from the compressor.


#43

100%

After Team Update 1, the intent of this rule was made abundantly clear. I hope teams stop trying to overthink it and twist the wording.


#44

Also an alternative: disconnect the compressor before you go into a match. This still abides by “addition, relocation, or removal of fasteners (e.g. cable ties, tape, and rivets)” stipulation under I4.


#45

I can imagine there was some sort of scene that occurred where a team that should have known better was found using an off-board compressor that wasn’t controlled by the robot.


#46

Holy smokes didn’t mean to start a flame war. I just seemed to remember a rule stating something to the effect FrankJ stated above.

From 2011 (and onwards), the rule that I seem to remember. I thought part B specified only one battery through a daisy-chain of a few rules.

R01: Energy used by FRC ROBOTS, (i.e., stored at the start of a MATCH), shall come only from the following sources:
A. Electrical energy derived from the onboard 12V battery (see Rule R34 for specifications and further details).
B. Compressed air stored in the pneumatic system, stored at a maximum pressure of 120 PSI.
C. A change in the altitude of the ROBOT center of gravity.
D. Storage achieved by deformation of ROBOT parts.

2012: Minor changes to 2011 wording, under R36
2013: Minor changes to 2011 wording, under R37
2014: Minor changes to 2011 wording, under R34
2015: Minor changes to 2011 wording, under R24
2016: Minor changes to 2011 wording, under R35
2017: Minor changes to 2011 wording, under R43
2018: Minor changes to 2011 wording, under R45

This in conjunction with the (2011) rule that has gone minor iterations (until this year):

R69: Compressed air for the pneumatic system on the ROBOT must be provided by one and only one compressor. This compressor may be either the compressor from the KOP, or an equivalent compressor that does not exceed any of the KOP compressor performance specifications (specifically: nominal 12v, 1.03 cfm flow rate, 120psi maximum working pressure). Compressed air shall not come from any other source. Off-board compressors must be controlled and powered by the ROBOT.

I also remember (apparently in err) that the power for a match had to come from a single battery. Not sure where I got this from, as I can’t find that rule in 2011 & onward. I suspect I mistakenly thought R34 (2011, minor iterations over the years) stated per match, but instead it states per competition:

R34: The only legal source of electrical energy for the ROBOT/HOSTBOT during the competition is one MK ES17-12 12VDC non-spillable lead acid battery…

Not that this all matters too much in the first place, a single match on a full battery will not normally drop it below ~11v, a single charge of a pneumatic system would not be enough to make a big difference.

I am still going to stand by my guns in saying a large precharge-tank, no compressor, & a battery voltage of 13.5v at the start of a match is still an advantage over a small pre-charge-tank, onboard compressor, and a battery voltage of 14v in pure terms of potential watts available to do work at match start*.

*I will admit I have not done the math on this however, if someone shows me the math otherwise I will freely change my mind.


#47

It was probably getting complicated to keep track of and verify that teams were doing it right. I recall things being kind of confusing on what exactly went on the robot and what went on the compressor when you compared it to a onboard system.


#48

I think :thinking: FIRST is trying to keep the pneumatics rules simple in the interest of safety :goggles:, or possibly President Trump’s Executive order of 30 Jan 2017. This year, they added the water filter (R84l), and something else had to go. :roll_eyes:

More seriously, but purely speculation: There are a few changes involving weight this year. There is no reason for a set of bumpers to weigh more than 15# to serve as bumpers (vs robot structure), so R30 freed up 5# from the amount FIRST accepted as safe for a two-person lift, thus an increase in R5. The weight of a decent compressor has come way down in recent years. These, combined with what I’m guessing were a number of shop compressors used to provide robot air over the years, made 2019 the perfect time to simplify.


#49

If you have a large enough tank you can pre-charge in the pit or in que with the required on-board compressor and avoid running the compressor during the match, right? Use the battery from the previous match of course. Yes, there is still a weight issue to deal with and space management issues but the draw on your match competition battery is avoided.


#50

We replace our battery but we run things at full speed so we suck batteries in one match. down to 9v. The rule says compressed air or battery, not that compressed air comes from on board battery.


#51

I never thought the rules were all that confusing, but a lot of teams had a really hard time understanding them and came up with some really goofy ways to run the compressor off the robot.

The idea that the off board compressor option allowed you to remove the compressor, and only the compressor, never really got through to all teams. It seemed like every event I’ve ever inspected for had at least one team with an illegal off board compressor setup, and it’s always a pain to sort it all out.