2015 FRC Inspection Checklist

[Tristan Lall]

Originally Posted by Jon Stratis

For this one, please ask the Q&A. Something like "Can we have an operator-controlled stop for the compressor, so long as the compressor will only turn on in accordance with the normal operation of the pressure switch?"

This is something that is NOT at all clear in the rules. A few years ago, I came across a similar situation with a team at champs, and pulled one of the division LRI's over (I can't remember if it was Jeff or Al...). At that time, it was ruled legal as the pressure switch did still control the compressor from a safety perspective. You may not get this same ruling from every inspector or even LRI, though, as it's a very uncommon situation.

I will say, however, that I think the rules, as they are currently written, are probably leaning in your favor. R77-D states "If connected to the roboRIO, the roboRIO must be programmed to sense the state of the switch and operate the relay module that powers the compressor to prevent over-pressuring the system." It says nothing about turning the compressor on at any point, just about turning it off to prevent over pressuring the system. However, as I am not the LRI at your event, my opinion won't mean anything without an answer from the GDC on the Q&A!

Originally Posted by EricH

That's a good one for Q&A. However, further reading of the checklist indicates that this is with no pressure in the system (AKA, empty pneumatics, which is a really really bad way to start the match in most cases). Starting with full tanks will keep the compressor from running. (There is also no rule stating that the compressor must be running when the robot is enabled--and for good reason, considering offboard compressors.)

I don't think that's a question that requires the Q&A—though if you think it would elicit more widespread understanding, go ahead. The past and present rules say nothing specific about when the compressor may or must start, only when it must not start (when at risk of "over-pressuring the system" or language to that effect).

The robot code libraries even provide a standard method for doing this that gives you the option to either run it under pressure switch control, or not run it.

[Jon Stratis]

Originally Posted by Tristan Lall

I don't think that's a question that requires the Q&A—though if you think it would elicit more widespread understanding, go ahead. The past and present rules say nothing specific about when the compressor may or must start, only when it must not start (when at risk of "over-pressuring the system" or language to that effect).

The robot code libraries even provide a standard method for doing this that gives you the option to either run it under pressure switch control, or not run it.

While I agree with that interpretation (which I think is clear in my post), that sort of behavior is not common. A majority of inspectors out there will see an unusual control scheme of the compressor and ask for the LRI, and most LRI's who haven't seen it before will sit there and scratch their heads... Their final ruling may or may not be correct in that situation as a result. The best way to ensure 0 problems at the event is to ask the question and make it absolutely clear for everyone that it's legal. With Q&A in hand, the team can help to educate their local inspection crew about a situation that, I think, we might see more and more of in future years (due to the "drive train arms race" and a desire to get as much pushing power as possible).