2013 running 2 - VI air compressors legal?

Is it legal to run dual air compressors this year? Would there be any practical plumbing problems to architect around?
Would there be an issue with using the FRC Labview Vi’s which are typically design around the use of one compressor and Nason shut-off switch?

See R80.

While R80 does specify that you can only run one on board compressor, it would be legal to run multiple off board compressors, so long as you include the control and plumbing hardware on the robot. IE 2 spikes, 2 regulators, 2 valves, etc. etc. etc.

Why would you want to? Its not like off-board you gain anything by having two, since the time between matches is so large.

Saver wear on the on-board compressor. And faster recharging for those back-to-back elimination matches.

I have yet to see an FRC compressor dead from wear in 10 years of competition. Not saying it doesn’t happen, just seems infrequent enough that it shouldn’t be a concern sufficient to warrant such an overkill solution.

and unless you have an extraordinarily large quantity of storage tanks on board, I’ve never seen an FRC bot take more than about 45-60 seconds to fill itself.

You and I have clearly had different experiences in FRC :wink:

Not that I’ve seen a dead compressor, but I’ve definitely noticed compressors getting weaker after a competition.

R80 applies to the compressor on board or off board. So either way, you only get one. But only your inspector knows for sure.

Compressed air on the ROBOT must be provided by one and only one compressor.
This gets everyone every year. You may not, under any circumstances, fill the tanks on the robot with anything other than one and only one FRC legal compressor under cRio control.
The motor on the Thomas compressor is very close to the same internal construction as a CIM motor. We have lost several over the years due to worn bearings, damaged or worn brush assy. or external metallic debris. The surprising thing is we have not lost a piston assy although the seals do dry out with use.

For Logo Motion our robot had 5 Pneuaire storage tanks that took ~5 minutes to fill.

For the record, I’m still of the opinion this is a crappy rule with unclear intent.

1075 built our power wheelchair-gone-forklift cart to have an onboard compressor, which was powered by the 2004 IFI control system that it ran on, controlled by a pressure switch just like an FRC robot, running the older Thomas compressor, just like an FRC robot, but we were not allowed to charge the system at competition with it, because the robot itself wasn’t controlling it.

Its no more or less safe, and the argument of it uses battery power from another source is silly because I can change the battery in my robot after I’ve charged the air system with the dead one from last match.

You can have your opinion but the rule is the rule. The rule is not presented as a safety issue, it is just a rule. Pneumatics will be inspected according to the pneumatics section. To remind everyone, you need to pass inspection in order to gain points and avoid other penalties. For instance read G5.

Not sure why you think my name is Phil (it’s not).

I don’t challenge that it IS a rule, nor that inspectors shouldn’t enforce it. Of course you need to pass inspection (presumably by complying with the rules) in order to compete. I think you’re taking the argument a bit far.

I do think that inspectors could have a hard time enforcing it though. For example, some of the robots that we had on that cart HAD their own on-board compressors, it was simply convenient to use the cart-mounted one.

We’ve been told not to use it to pressurize the robot before and complied, and the volunteers at the event(s) it was mentioned at seemed to indicate that it was somehow a safety concern because the robot wasn’t controlling it, and that was the logic behind the rule.

I further believe though, that questioning the reasoning behind a rule is VALID, and IMPORTANT, because often, even though a rule may have made sense for one reason or another in the past, doesn’t mean it still makes sense now. Intent is important. This is a rule that has been around for years, for what appears to be no reason at all.

To be sure, this is the specific portion of the rule I don’t understand the reasoning behind.

The only reasoning I can come up with, is that they want you to be under software control so the pressure switch will shut things off appropriately. There are lots of ways to solve that without requiring the robot to be the one controlling it.

A better rule might read:

“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 still be controlled by a pressure switch to ensure a maximum pressure of 120psi.”

I apologize if my preference for a rulebook which promotes maximum freedom of configuration to the teams, while still achieving its goals doesn’t sit well with you. The way the bumper and other pneumatics rules keep getting simplified and loosened, and the way HQ has expressed a desire to simplify the rulebook seems to agree with me. “That’s the way we’ve always done it.” just isn’t a good reason to continue doing something a particular way.

I thought Phil was your name. Sorry. There is no mystery to the reason behind this rule. It is in the first paragraph of Section 4…

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.

Emphasis mine. Think about this rule as being as hard and fast as the robot battery, the PD, the legal motor list and cRio. The penalties show how serious the GDC is about enforcement. For instance…

When placed on the FIELD, each ROBOT must be:
A. in compliance with all ROBOT rules (i.e. have passed Inspection),
If it is not a quick remedy: the ROBOT will be DISABLED and must be re-Inspected.

ROBOTS whose operation or design is unsafe are not permitted.
Violation: FOUL & DISABLED. If the issue is due to design: Re-Inspection.

A TEAM is only allowed to participate in a MATCH and receive Qualification Points if their ROBOT has passed
Inspection. If it is discovered after the start of the MATCH that a ROBOT did not pass Inspection, the entire ALLIANCE will receive a RED CARD for that MATCH.

At the time of Inspection, the ROBOT must be presented with all MECHANISMS (including all COMPONENTS of each MECHANISM), configurations…

To use a second compressor of any type means that the robot has not passed inspection. I think that covers it…

We clearly don’t see this as an issue of the same, or even similar magnitude. You continue to argue about how it constitutes a violation worthy of claiming a ROBOT wasn’t inspected simply because its air system was pressurized by some other source, regardless of whether that source is substantially the same as the presently prescribed system or not.

You just made the argument I’ve heard so many times, that it needs to be supplied by the ROBOT’s battery, because everyone has those, and they have a limited supply of power, so that makes it the same for everyone.

The source of the 12VDC power that powers the compressor is irrelevant in any substantial way, since I can change my battery AFTER I’ve pressurized the system and before the MATCH. Whether I use a robot battery, a deep cycle marine battery, or a solar fusion reactor to power it changes nothing about the ROBOT as it sits in the ARENA at the start of a MATCH, with a fresh battery and a pressurized air system.

As for the rules you cited:

G03 doesn’t apply, its not an unsafe design or operation.

G05 may apply, but it IS a quick remedy, opening the air valve remedies any perceived problem that charging from an external source created, so no DISABLED ROBOT or Re-inspection necessary.

And I suggest that T06 or T08 aren’t even relevant to the discussion, as I never suggested more than one compressor.

For sake of argument, though, I don’t believe that the intent of the “one and only one compressor” rule is to prevent me from having equally functional, and equally legal on their own off-board compressor panels (controlled and powered by the ROBOT, in accordance with R80), but rather, its intent is to say that you are only to have one compressor provide the air at any one time. Whether this time I use compressor A and next time I use compressor B doesn’t particularly matter, otherwise, what happens when one breaks during a competition?

A proper Q/A is probably in order, but let me test the waters here first:

The offboard compressor must be controlled by the robot as if it is on the robot. The benefit of it being offboard is that its weight is not part of the robot. I.E. it is NOT part of the robot.

Here is my question: Can you have the newer, smaller compressor, on your robot (used during matches to keep your air supply topped off) but use the older, larger compressor offboard to fill your tanks between matches? This would be accomplished by disconnecting the leads from the onboard compressor and connecting them to the offboard compressor and using the existing sensors and power supply. The robot is always receiving air from one and only one compressor.

There are three reasons for this:

  1. As Jimmy already pointed out, a robot with a substantial amount of stored air can take a long time to refill. While this shouldn’t be an issue in qualifying, as you go deeper into elims, time is less between matches. There is a significant difference between the time it takes the two types of compressors to fill large quantities of storage tanks.
  2. The smaller compressors get REALLY HOT quite quickly. Even the larger ones get pretty darn hot after a few minutes of continuous run time. The ability to use two compressors saves wear and tear on both.
  3. I’ve been near a robot that had a brass fitting burst because it was connected to the compressor which got so hot the brass softened and couldn’t handle the pressure. Not a catastrophic failure like the plastic tanks, but still quite dangerous.


The issue of spares is what really drives my disdain for this rule.

If I can switch compressors and batteries because spare parts are allowed, then apart from annoying everyone unnecessarily, all this rule accomplishes is to mandate that the cRIO controls and robot’s power distribution system be used. That is unnecessary from a practical point of view, because there are plenty of simple mechanical devices (fuses, pressure switches, regulators, etc.) that can control the system without human or computer intervention—and the pneumatic ones are required anyway! Mandate a proper fuse/breaker on the compressor, and that failure mode is mitigated, without resorting to full robot control.

This rule should not exist in its current form, but it does—and with great regret, will be enforced vigourously.

Are you sure that was the failure mode?

For every design decision we make, we have to weigh the trade-offs. Why is “our tanks have so much capacity that we may not be able to fill them between elimination matches; is that worth the risk?” any different than “we can’t figure out how to make room for both floor pickup & climbing on the bot; which is more important?” Whether we like any particular rule or not, some (most? all?) of them are there (at least in part) to help level the playing field.

Of course we don’t agree, but every other team at your event expects, no demands, that every robot be inspected to the same standard so that they can be sure they are not competing against a team that has an advantage, of any kind.

I did not make that argument. The rules state the compressor must be controlled by the cRio and robot battery.

While the choice of power source is debatable, the cRio still needs to be powered by the robot battery and so does the control for the compressor.

Your telling me it is safe does not make it safe. I can assure you that inspectors find unsafe conditions on robots regularly at every event. While opening the relief valve can be a quick fix, why should the event staff, the refs or other teams be forced to endure this match after match.
T06 & T08 are extremely relevant and provide the basis for inspection and the remedy. If you use something on your robot during the competition, it must be inspected. If you use it without it being inspected, you are in fact, not inspected. The remedy is no points for each match you are scheduled for and a Red Card for the entire alliance if you enter the field and the match starts.

The intent of “one and only one” in no way can be interpreted to mean more than one. If your one compressor should fail, a spare may be installed and that also should be inspected. It is the reason the inspection staff is on duty all weekend.

To reiterate the procedures for everyone to understand, the LRI, Head Ref and FTA act as a group when something that will affect a team occurs. If the LRI finds that a team has an issue, he brings it to the Head Ref and FTA for discussion. If the Head Ref sees an unsafe or questionable part on a robot, he calls in the LRI and FTA if needed, for discussion. If the three key volunteers still cannot reach consensus, each of us has the phone contact info for higher authority. Each one of the key volunteers is tasked with keeping the event safe, operating within the rules of the tournament, for the enjoyment of all. We take that task very seriously.

The incident that Kevin related above occurred at the Midwest Regional in 2011. A team trying to find an air leak had bypassed the compressor control to keep the compressor running. The heat buildup caused a failure of the tubing and fitting at a brass junction. The failure sounded like a gunshot and any pieces were contained within the robot.

Precisely what my point has been all along. At least some LRIs are capable of understanding reasonable thought. I have never argued that the rule somehow isn’t the rule and that I don’t need to follow it. I’m arguing that the rule is baseless and silly, and achieves nothing in terms of increasing safety or levelling the playing field.

Again, show me how this provides me a tangible advantage of any kind, and I will concede this point. Of course we should all be inspected to the same standard.

So, you’re using the rule to justify its own existence? My argument is that there is no need to require the cRIO to be the one controlling or powering the compressor.

What have I said that suggests I don’t want my compressor setup inspected? It SHOULD be inspected, the rules are currently needlessly restrictive is all. IIRC the inspection checklist has an item for inspectors to check which reads something to the effect of “turn on compressor; does it shut off automatically at 120psi?”. I’m certainly NOT championing for the removal of such an IMPORTANT safety check.

If “one and only one” can in no way be interpreted to mean more than one, then spares are not allowed. I think we can agree that since that is clearly not the intent of the rule, it must mean that we are not to be using two or more compressors in parallel to speed up the process. This serves the goal of leveling the playing field and I agree that this rule should be continued but have its wording clarified such that its intent is clear.

So a team testing their robot in a manner that involved purposefully bypassing at least two safety interlocks caused a catastrophic failure of a robot part by overstressing it. THAT seems like a legitimate safety issue, which I’m sure the Safety advisors at Midwest 2011 spoke to the team in question about.