Precharging

We added some new components to our robot that are actuated with pneumatics. However, the only way we fit in the frame perimeter is with the pistons actuated, requiring air in the system. We’ve read up on precharging the system however we don’t have an extra compressor or relay (we have 2 control systems+pcm). Our current solution is to enable the robot in queue to charge the system and then hold charge until the match starts. Is there a way we can manually enable the compressor without connecting to and enabling the robot?

It is required that the compressor be under RoboRio control whether before or during the match. Bypassing that would be in violation of the rules. Charging while in queue (enabling robot with tether) is the commonly used method.

I don’t recall where I read it, but I do understand that at some venues, the robot may not be enabled in the queue. If you need air to stay within the frame perimeter, you may have to charge the tanks in the pits.

It is probably worthwhile to find a way to stay inside the frame perimeter that does not require the air. On one of our robots, we had a part that was held in by a light bit of yarn that the robot broke early in each match.

Enabling in queue varies from event to event. Some have tight queueing areas and the staff at those events don’t allow it just in case something goes wrong. But, regardless of the venue, you are allowed to pre-charge the pneumatic system. You might have to do it at your pit, but you can have the full 120 psi when you get to the field.

Painter’s tape or gaff tape works as well. I’ve seen a few of those robots. Just make sure to swap the tape between matches.

All of the above and surgical tubing, rubber bands or some other stretch (left over bumper cover elastic) material.

This past weekend at the West Palm Beach regional (Formerly South Florida Regional) Inspectors were instructed to have teams de-pressurize between the pit and the field. Apparently, according to the Lead Inspector, having pressurized air outside of the field sets up a dangerous condition. We (successfully) argued pressurizing on the field was not only against the rules (tether rule) but would cause huge delays as teams spend several minutes pressurizing on the field.

The danger of an out of control robot is a real one, as teams attempt to pressurize their robot in the queue. The depressurization rule, and initial compromise (you can pressurize in the final queue position) set up a condition where a robot was still in auto, and took off running into several people. Finally, after many matches, the head inspector saw the light on the potential issues with field delays and the real danger (run away robot) and allowed us to pre-charge before entering the field… This leads into a conversation about FIRST adding rules (even if in contrast to written rules) in the name of “Safety.” Further, FIRST likes to email inspectors hidden “rules of the event.” We only know about these rules since we have a volunteer inspector on our team, all other FIRST teams are not privy to these “rules of the event.”

At all of our events this year and previously we have always come back to the pit after a match, fixed anything that needed fixing, then changed bumpers if needed, then charge pneumatic system, then change battery. Never been an issue.
Semi strange how things can vary event to event, more symmetry is needed imo.

This does not happen! There is no general email that goes out to Inspectors that changes rules. There are no hidden rules, ever. We do, however, enforce Team Updates and Q&A up to the start of the event.
Safety is our first priority. If the venue requires really tight quarters in the queue, then they may ask (The LRI is the messenger) teams to remove any air in the expectation that injuries will be minimized. If your robot moves when pressurized, I would ask you to wait to pump up. If you consistently demonstrate an unsafe condition, the LRI, FTA and UL Safety people will visit you with suggestions up to and including disabling the offending parts until you can correct the condition. (See R9)
Lead Robot Inspectors do have a conference call each week. The past week’s events are reported and the upcoming week LRIs have a chance to ask questions about ruling on certain issues and what problems that have been seen. Further, all LRIs have my personal phone number as well as others at HQ. They can call me or HQ for rulings on things that are out of the ordinary any time.

I dunno Al. I think this is the exact thing James is concerned with. This is the first time I’ve ever read about teams being told to de-pressurize after leaving the pits and before entering the field. That specific scenario is definitely not in the rules and (IMO) is very subjective. (edit) - If this were about de-pressurizing after a match, then I see the point and understand the de-pressurization even though it’s not in the rules.

There are other instances of this happening with pneumatics as well. For example, some RI’s still do not believe plastic pneumatic tanks should be allowed and give them extra scrutiny in the name of ‘safety’.

Is the de-pressurization on a per-team basis, or does it impact everyone with pneumatics at the event when such a request is made? Who makes the call on what is ‘safe enough’?

Jesse,
Inspectors are trained to inspect all plastic tanks to insure that a team hasn’t used one of the tanks that disintegrates. We are still finding them on robots.
R77
K. Pneumatic storage tanks (with the exception of White Clippard tanks P/N: AVT-PP-41)

Most teams haven’t heard of this practice because only a few venues require it. This is similar to the power restrictions at some venues.
Some teams who have never used pneumatics before have issues where major parts of their robot move during pressurization. I don’t think anyone here would want to be standing in the queue when a robot next to them bangs a student in the back or head.

I’ve found two of the AVT-PP-41 tanks this year and had them removed from robots.

1)This is a situation that would be a good place for a request (Gracious & tactfully made) that the LRI consult an higher authority such as Al. T18-A clearly shows that teams can use precharged springs & pneumatics to maintain legal staring configuration. This is so universally done, I am a little surprised it took so long for the feedback to take hold, but not being their I can’t be too judgemental.

This is also a good example of safety being a lot more than simple rules. Safe to say that for most robots, having charged pneumatics is safer than enabling robots in queue. Our robot is actually marginally safer with the pneumatic pressurized.

i think I get it a bit better now.

It’s still concerning though - it effectively forces a few extra restrictions on teams which use pneumatics. If the team doesn’t remember to start charging immediately when allowed, there’s a very good chance the system will not fully pressurize and there may be air problems for the team during the match. In addition, if a system takes longer than ~5 minutes to charge, then the students won’t have enough time to fully charge during any given year’s match cycle time. This puts an effective cap on the amount of air a team can expect to use.

Will we know in advance whether a venue will have this restriction?

I agree that I would not appreciate getting hit in the head, but I still agree with Jesse. Is is very possible to charge a pneumatic system with little to no danger. There are much more dangerous things that are allowed in queue (I’ve seen teams run flywheels, test their drivetrains, etc). Of course if an inspector observes an unsafe charging pneumatic system, they should instruct a team to make it safe or not allow it, but that should stand for any system that isn’t safe. I don’t see the need for special rules at some events outlawing all pre-charging pneumatic systems. I appreciate FIRST’s desire for my safety, but sometimes they do more than they need to.

The bigger problem I have is the secrecy around this rule. If this is going to be a rule at some events, it should say in the Game Manual which events will be following this rule. I know last year it took my team almost 5 minutes to fully charge our pneumatic system. This was fine because we knew (or at least thought we knew) that we would be allowed to pre-charge in the pits and in queue. If we got to our event and we found out that we weren’t allowed to pre-charge, we would not have had a fieldable robot. It’s one thing if the teams know about this in advance and can design with this in mind (like we do with all of the other rules), but its completely different when this rule is sprung on us when we get to competition.

This confuses me. So teams with offboard compressors can’t use pneumatics at some venues? If there is a rule at these venues to dump all air in queueing, there is no opportunity to fill the tanks and change the battery between queueing and being on the field for the match. Not to mention how this hurts teams that take more than 2 minutes to fill their air tanks. If this is a constraint teams should expect to ever have to deal with, it should be in the rules so that teams don’t design robots that are disadvantaged in these scenarios.

I know you’re just the messenger, talking about rules at specific events, but this just seems like a really big deal at first glance. I think I’m misunderstanding the situation here.

You would have to bring the off board compressor with you to que. not a huge deal seeing as it must be powered by the robot per rules anyway.

Depends on the cart, TBH.

When charging your pneumatic system, expect things to move. especially when using air pressure to hold starting configuration. Most solenoid valves used in FRC will pressurize one side of the cylinder when disabled. The only way to charge the pneumatics is to enable the robot. Depending on the robot not to move when enalbed is an unsafe mindset.

Yeah, no, it’s a huge deal.

You can’t tether to the robot on the field, so you would have to precharge while queueing - but if you’re not allowed to charge while queueing either, and you’re required to dump air in the queue line, it’s impossible to start the match with air.

It is legal and sometimes a very good idea to build a robot with no on-board compressor, but with many air tanks. These tanks can take upwards of 2 minutes to fill. These robots basically need to be filled in the pit or partially in queueing in order to be able to compete. If these designs are feasible at some competitions but not at others, that really isn’t fair.