Off robot air compressor
 

at the phoenix regional here w have 1 tank and no compressor on our robot. The inspectors are saying we must fill it with the KOP compressor. They say we may not use our own compressor off the bot to fill the tanks. Ours is actually lower psi and much safer of a setup.

Was this in the rules? What difference does it make which compressor didbthe compressing. Isn't compressed air compressed air no matter what brand compressor it comes from?

Re: Off robot air compressor
 

yeah, its in the rules that you can only use the suppled KOP compressor for your robot.

part of it is a safety issue. Compressor tanks tend to get water in them, and after a few years they must be discarded even though they look like new on the outside.

I would not want to be in the pits next to a team that dragged in some 30 year old compressor they got at a garage sale. Im sure thats not what your team intends to do, but FIRST has to draw the line somewhere.

So thats where they drew it: KOP compressor only.

Re: Off robot air compressor
 

Yup.

R96 - Pneumatic Storage
Teams are not allowed to remove or adjust the 125-psi set relief valve attached to the compressor.
You may only use the Thomas Industries compressor and Clippard Instruments air storage tanks provided in
the Kit to compress and store air on the robot. You may not use extraneous lengths of pneumatic tubing to
increase the storage capacity of the air storage system.

Re: Off robot air compressor
 

That is one drawback of pneumatics as far as we are concerned.

To use pneumatics, you are required to have on your bot the cylinder, solenoid valve, compressor, tanks, gauge and anything else for your system.

The bad thing is that all that is added into your weight.

If you need one little cylinder on your bot, you are talking 10lbs just for the system to run it.

Sometimes it's not even worth it.

That's why we scrapped pneumatics this year in lieu of motors this year.
We actually saved weight.

Re: Off robot air compressor
 

Also of note, when using the off-robot compressor:
You MUST:
Put a 20A breaker right after the power source
Put a spike in between the compressor and the power source

We found the spike part to be quite a pain in the behind. We have it set up now so that we plug it into the last relay port on the robot and that trips the spike.

Otherwise, you are not legal.

Re: Off robot air compressor
 

You do not need the compressor on your robot. You just need to
use it to fill your tanks. We use a minimal amount of air on our
robot and we drag the KOP compressor along to fill the tanks
between matches.

Re: Off robot air compressor
 

what Eric said - you can make a very small / very light package for pneumatics if you only put one tank on your bot, with one small cylinder, the pressure gauge and one valve.

Re: Off robot air compressor
 

Hmm.. Can you quote where in the manual it says you do not need to have a compressor on your bot? I was under the assumption from what we have done in the past that it had to be on their.

Re: Off robot air compressor
 

Rule <R95> from The Robot
This seems to say you do not need the compressor, if your prefer, and can charge it prior to a match.

-Nate

Re: Off robot air compressor
 

To add to Nate's post...
<R97> The Nason pressure switch must be connected to the output end of one of the Clippard tanks to sense the tank’s pressure. The two wires from the pressure switch must be connected directly to a digital input and ground terminal on the Robot Controller, and the controller must be programmed to sense the state of the switch and operate the spike relay that powers the compressor. The Parker Pressure Vent valve must be connected to a Clippard tank such that, when manually operated, it will vent to the atmosphere to relieve any stored pressure. The valve must be placed on the robot so that it is visible and accessible.

Although First is trying to decide what to do in this case, thus far (as in the past) it will be necessary to connect the pump through a Spike relay as specified above. Most teams to use this method, connected the pump output to the Parker Valve, then close it when up to pressure. In the past, it was then possible to demonstrate that the pnuematic system was able to achieve no greater than 120 PSI at the high side (Clippard Tanks) and that there was some kind of automatic shutoff that could be demonstrated for the inspector or field personnel. At a minimum expect that field judges will check your pressure to be sure it is not higher than 120 PSI, the consequence could be to drain your pnuematics before competing or possible DQ.
As always, anything that looks unsafe in any way, will not be allowed.

Re: Off robot air compressor
 

As a note, the system they are making us use is very dangerous. Nobody has another relief valve we can use so we bleed off the line from compressor to robot. So when we are done filling, we are pulling off a pressurized 120psi line. Very bad. The system we had before was much more safe, with a quick release and everything. We were too safe for the rules. :confused:

At least they aren't making us use a Spike.

One odd thing though is that they said we may use whatever tank we want off the robot.

Nothing against inspectors, they are just enforcing the rule. But the rule is putting us in danger, and is highly illogical. My 120psi air is just as good as your 120psi air, is it not?. Air is air. The only difference is in safety while filling, and our old system was superior. Regulated and quick released, and impossible to be over 100 psi.

PS. does anyone have the exact corresponding rule from last year?

Re: Off robot air compressor
 

Sandrag,
The rules are nearly identical to last year as quoted above, only the numbers have been changed to protect the innocent. The inspectors have been told that the kit compressor must be used and if off the robot, must use a spike to control it. I agree that unsafe practices must be avoided, no exceptions. What does the safety officer have to say on this one?

Re: Off robot air compressor
 

who said you could use a tank off the robot?

why would you want an external tank to charge your robot?

Re: Off robot air compressor
 

I have read update 18 and understand that FIRST wants us to hook up our off-board compressor to a robot controller and use a spike, pressure switch and all that. Is this really going to be enforced? In L.A. we were told that we had to wire an in-line 20 amp breaker in case of short and prove that we had the proper regulators and that we could not pressurize the robot to over 120 psi. We did all that and had no further issues. Do we really have to shell out $600+ dollars for another controller and go through all the hassle of programming and wiring it up or will our in-line breaker be sufficient? I am mainly looking for input from lead inspector or other official personnel at nationals.

Re: Off robot air compressor
 

a spike can be controlled w/out the whole robot controller. i would have to look up the exact pinouts but we put our compressor on the cart and used the presure switch and a spike to control it. pm me if you realy need the diagram cause ill dig one up.

Re: Off robot air compressor
 

I am not Dave Lavery, but the inspector in me says the compressor has to be wired like it is on the robot. If you keep the required Spike and compressor off the robot, you'd make three connections to the robot in order to have a legal setup:

1) To the 20A breaker on the panel, for power
2) To a relay output on the RC, for control of the Spike
3) To the pneumatics system, for obvious reasons.

I'd like to hear what the other inspectors have to say about this idea, as I'm not a pneumatics whiz.

Re: Off robot air compressor
 

The expectation is that you use the robot controller on the robot to run the compressor using the default code. You may mount the spike and compressor together off the robot. You may even charge the system through the relief valve. As Team Update 18 outlines...
"Off-board compressors – We would like to remind teams that Rule <R95>
allows a team to leave the Kit-Of-Parts compressor off the robot but still use it
to charge their pneumatics system with pressurized air, thereby saving
weight and volume on the robot. However, Rule <R95> does NOT allow a
team to bypass any of the other pneumatic or electrical system rules. In
particular, even if the compressor is located off-board of the robot, the robot
and compressor must still be in compliance with Rule <R90>, Rule <R96>,
and Rule <R97>.
We recognize that inspectors were given more lenient guidelines, but want to
make sure that all teams are aware of the expectations and will be held
accountable for this pneumatics configuration going forward."
The compressor must be powered by the main battery via a 20 amp circuit breaker and a spike which may also have a 20 amp circuit breaker instead of the fuse. This would allow teams to remove the weight of the compressor and spike and some wiring from the robot overall weight without violating any of the other robot rules concerning electrical wiring protection or maximum pressure (limited by the RC and pressure switch).

Re: Off robot air compressor
 

Does this mean that you will be looking for a only a spike and breaker? So we don't have to have an robot controller or pressure switch?

Re: Off robot air compressor
 

We have the Spike on the robot, so our power is already controlled. But in order to make the Spike work, we also have to tether the robot to an OI.

(We use a spare OI from last year, with no switches or joysticks connected to it, but it works to let the RC run and control the compressor.)

Re: Off robot air compressor
 

Kirk,
All robot rules apply. You must have the minimum requirements for a pneumatic system. Gages, pressure switch, tank(s), regulator, relief valve, spike, breaker, compressor, etc. You will be asked to demonstrate that the compressor is under the control of the RC and automatically shuts off at 120 PSI under software control during the inspection process, just as if the compressor was on the robot. These rules are the same as previous years.

Re: Off robot air compressor
 

Not according to the "2006 FIRST Welcome to Robotics Inspection Rev D" document on FIRST's website. Under "What's New for 2006":
Earlier in the same document, there is this statement:
(emphasis mine)
Notice the difference between "is required" and "is not required" - I guess it's not surprising that there's so much confusion over this rule...

Re: Off robot air compressor
 

the document you referenced has two conflicting rules. We cannot assume one of them is correct and the other is wrong. Clarification (correction) is required from FIRST.

Re: Off robot air compressor
 

Yes, I know, and that document is not a rules document anyway. At any rate, it has been clarified by FIRST:
I was just pointing out that this issue has not been "cut-and-dry" and thus I'm not surprised that teams are confused. What really bugs me is that I can't find anything in the "Robot Rules" document that says that the spike, and pressure sensor, and other rules apply to a compressor off the robot, and no one yet has been able to give me an explanation as to why I should have assumed that they do. There's plenty of other devices that are used "off-robot" that don't seem to fall under the jurisdiction of the robot rules and I don't see why this is any different (I don't have a problem with this being a rule, I simply have a problem with it not being stated that way). Obviously based on Q&A answers it does, but prior to the Q&A it was not explicit.

Re: Off robot air compressor
 

FIRST provided clarification in the form of Team Update #18.

Re: Off robot air compressor
 

Whoops! I'll take full responsibility for that one. An inspector pointed out that discrepancy to me last week. The "welcome doc" was not properly updated when it went to Rev D. Item #47 on page 12 should read "The team is required...".

Sorry about the confusion. FIRST is expecting that off-robot compressors will be wired and controlled exactly as if they were located on the robot (ie 20A breaker + Spike + on-robot battery + Nason pressure switch + RC to sense switch and enable the Spike).

Russ

Re: Off robot air compressor
 

It seems clear to me that the robot rules apply to all of the pneumatic system components used on a robot. Using pneumatics with an off-board compressor as permitted by <R95> does not change the rules that apply to other pneumatics components and to the pneumatics system as a whole.

Another example of robot rules applying to interaction between a component used on the robot and an off-board component is the 6A rating for battery chargers, <R52>. The two rules (<R52> and <R97>) have the same purpose; i.e., automatic regulation of energy storage in robot components.

Re: Off robot air compressor
 

The difference here though is that with the charger, there is a specific rule stating the requirements even though it's off the robot. With the compressor, the only rule in the rulebook is that the pneumatic system must only be charged with the KOP compressor - the rest of the rules apply to the electrical system on the robot. When I use my laptop to program the robot, I don't power it with a Spike from the robot battery, so why would I assume that any other tool I use on my robot in the pits would be under such a requirement? Before all this discussion took place I would not have hesitated to connect the compressor to a battery with an in-line 20A breaker (and in fact many teams have done this in the past, and I would consider it safe that way). What other rules in the "Robot Rules" section now apply to things not on the robot? I've seen teams use a DeWalt drill to wind up systems using latex for stored energy - these are not legal kit motors and are not wired correctly, and use an illegal energy source - is this no longer acceptable either? Why would I assume a "Robot Rule" applies to something not on the robot if it's not stated explicitly (as is the case with the charger)?

Anyway, my concern is that if this was the intention all along, why not just state it in the rules? Perhaps it was just an oversight and I understand that happens, but once this was realized (i.e. when it was added to the inspection checklist and other inspection documents) I think the rules should have been updated as well. Perhaps the people writing the rules thought it was clear (and I can understand that too) but obviously many people didn't understand it - I think this is good feedback for next year that if rules are expected to apply to something even when it's not used on the robot then it should be stated that way.

{edit} I should add that my team doesn't even use an off-board compressor. The reason I am talking about this is because as an inspector, I really hate having to tell teams that they have to completely re-do some part of their robot. I especially hate doing it when they look at me and say "where does it say that in the rules" and I can't really point them to anything other than some vague rules which they can easily argue about. When something like this isn't clear these teams often feel that they've been slighted or singled out or hassled unnecessarily by an overbearing inspector, and that takes something away from the competition. {/edit}

Re: Off robot air compressor
 

Dave, I agree completely with your point of view.

My team has not used an off-board compressor (yet); in fact we've avoided pneumatics altogether for the last two seasons. My concern with this rule is the same as yours. I don't like to pick on teams needlessly during inspection.

At Waterloo this year, Tristan and I saw two teams with off-board compressors. One complied the the earlier inspection "welcome doc" guidance requiring a Spike but no pressure switch; the other had no Spike. In each case the team was pressurizing manually; i.e., by reading the storage pressure and manually switching the compressor off when it reached 120 psi.

We asked the team without a Spike feeding their off-board compressor to go look at how the other team had complied with the inspection checklist guidance: basically they had a mechanical switch enabling the Spike. We passed both teams after each had demonstrated apparently 'safe' pneumatic charging procedures.

During the next lead inspectors teleconference, several questions on the pneumatics requirements were raised. One of the most experienced lead inspectors pointed out that the inspection checklist guidance we had all been working from up to then was inconsistent with <R97>. Like you and probably many others, I had missed that. So had FIRST headquarters.

FIRST issued Team Update #18 to address this inconsistency. As I said earlier, it is now clear to me that the same pneumatics rules apply whether the compressor is on-board or off-board. But that was not clear to me when I was inspecting at STL and Waterloo.

Re: Off robot air compressor
 

Doesn't the relief valve vent pressure past +-125psi? If that is the case, all of the requirements for the spike, RC, pressure switch, OI, etc seem redundant.

We'd be better off bringing last years robot to charge this years pneumatics... it all just seems a little overkill to me. The spirit of the rule is to maintain safety. I don't see how all of the other systems really help that much. If the pressure switch fails, isn't the backup the relief valve anyhow?

This all is very reminiscent of the battery terminals that were being enforced last year... we're becoming lawyers again.

Re: Off robot air compressor
 

I want to be as diplomatic as I can when I say this ........

I sincerely hope that no one expects an inspector to allow a team to break a rule because they, in their humble opinion, think the rule is "overkill" or "redundent". It is our job as inspectors to apply all rules to each robot to the best of our ability. We don't make the rules, we just expect you follow them. Let me go on the record as one of the 4 lead inspectors: If you break a rule, you must fix the violation or you will not pass inspection.

Something I hear all of the time is 'but our robot passed inspection at <insert regional name here>". Please keep in mind that we (the inspectors) have no idea what you have done to your machines after inspections at the regionals nor are we inclined to believe that no one made inspection mistakes. You should expect that inspections at the championship will be tougher. The folks that volunteer for inspecting at the championship are generally more experienced.

Please follow ALL RULES . If your not sure about something, ask the lead inspector for your division early Thursday. This way, if there is a problem, you'll have time to correct it.

Stay cool ...... Have fun ....... :cool:

Re: Off robot air compressor
 

Not beat a dead horse but I want to see if others agree with me.

Wouldn't it be simpler to require the pressure relief valve (PSV) be mounted to the accumulator (ACC) or the vent valve (HV). This would make it very clear that the system was at a safe pressure and would eliminate the need to have many of these systems on the robot.

I have been a proponent of this for several safety reasons but it should also simplify inspection and allow for any charging source. If you over charge the ACC you will actually be at the lower reseating value of the PSV. Also having only the HV to vent does not adequetly prevent several potential over pressure issues particularly when a robot is shipped pressurized and exposed to extreme temperatures (in excess of 150F).

I have all season since reading the pnuematic rules related to an off board compressor been extremely disappointed with the wording. I would like to see FIRST take some of these items into account when writing next years rules.

Re: Off robot air compressor
 

Further to Ed's comments, I'd like to point out to anyone who's interested that the inspectors do discuss controversial topics like the necessity of the off-robot pneumatic requirements. And sometimes, we, like many of you, feel that certain rules (and their interpretations) don't always stand up to close scrutiny. If that's the case, the concerns are relayed to FIRST itself, to be considered for inclusion in a team update.

The trouble is, we've got the added burden of maintaining consistency and legitimacy throughout all of the events; this means that we deliberately restrict our flexibility in making rulings, because we wish to avoid situations where rules are applied unevenly, especially when we know that the issue is unresolved.

But, as Richard stated, even if the rules themselves are constant, the interpretations can change over the course of a season. When dealing with some contentious issues, what was properly ruled legal at a Regional will not necessarily be again ruled legal at the Championship, primarily because the inspectors at the Championship will settle upon standards that reflect the most up-to-date experiences of the entire FIRST community, while still adhering to the letter of the rules.

Basically, though my initial study of the off-board compressor rules lead me to agree with Dave's interpretation, in the later weeks of the season, FIRST has repeatedly clarified, both in the unofficial Q&A, and in an official update, that the rules should be interpreted differently. The Championship inspectors have agreed to interpret the robot rules as being applicable to off-robot compressors, and teams will therefore be expected to make the necessary modifications, even if their robot passed inspection elsewhere.

Like many people, I feel that the pneumatics rules could use a thorough re-write, but FIRST couldn't reasonably make that sort of change during the season, even if it wanted to. At the moment, the best solution is to express your views at the team forums, and to the appropriate FIRST personnel, all the while bearing in mind that those views won't necessarily sway an inspector into ruling in your favour at this event.

Re: Off robot air compressor
 

Correct me if I am wrong, but not once did I mention that we weren't going to follow the rules. I agree that all teams should follow all of the rules. We have every intention of making our off board compressor legal. I was simply pointing out how frustrating these things can be. It is evident that the rule was a little unclear to almost everyone. As an inspector at SVR, I know of more than a few teams who had no idea of the complexity of the 'FIRST approved' off board compressor setup. Venting frustration is alot different than expecting to pass with an illegal setup.

Re: Off robot air compressor
 

Travis, I'm sure I could have worded my response better and I understand the frustration with this particular issue. Unfortunately when I read your last post, it reminded me of the dozen or so mentors that have stood toe to toe with me in the past quoting comments very simular to yours about rules they did not agree with. Believe me, inspectors can get a little frustrated too. I was trying to make a point but it looked like a personal attack and for that I appologize.

Re: Off robot air compressor
 

Hi. Looking at pneumatics for the first time. It seems that rule <R103> (2007 manual) is silly. It requires that the robot controller monitor the pressure switch and turn off the compressor when the limit is reached. Wouldn't it be much safer to put the pressure switch in series with the input signal to a spike and have the compressor safetly turn off when the pressure is reached without worring about the controller and software having to monitor it?According to <R103>, what the previous posted said would not be legal.

Brian

Re: Off robot air compressor
 

Brian,
In order to keep in line with other parts of the manual (electrical) and in keeping with good electrical practice, the best solution is for the limit switch to be monitored by the RC and controlled through a spike. This switch does not handle the current reguired for compressor start and there can't be anything that controls a spike except the RC.

In addition, for all teams using the compressor for the first time, it is acceptable to replace the 20 amp fuse with a 20 amp circuit breaker on the spike that is used for the compressor. The start current for the compressor can exceed 20 amps for a very short time and the fuse will fail after a few starts.

<R65> ...
The fuse on the Spike relay for the air compressor may be replaced with a 20 Amp Snap-Action circuit breaker.

Re: Off robot air compressor
 

...of course, that post was from a year ago, with different rules.

Don

Re: Off robot air compressor
 

But unfortunately not substantially changed. The rules about off-board compressors are among the silliest in FIRST. From an engineering point of view I don't see any difference between air supplied by one compressor or another as long as they are at the same pressure. If there is a difference I wish somebody would provide us with a clear explanation as to what it is.

At the same time the rule is not that hard to comply with so as an Inspector I have to enforce it. I just don't have to like it.

Re: Off robot air compressor
 

Chris,
A team with the compressor on the robot must show that the compressor shuts off under RC control. By placing the compressor out of the robot, that rule must still be satisfied. Inspectors, as you know, have a hard enough time inspecting normal conditions, this rule should not cause a non-experienced inspector any trouble if there is a pressure check on the inspection list. Letting teams charge up the tanks with other compressor combinations may or may not give them added advantage but from a safety standpoint, I want to know that robot standing next to young field setup volunteer doesn't have more than 125 PSI onboard. If a team uses the pressure switch/RC/Spike combination then there are no worries.
As I interpret the rules, the compressor, pressure switch and spike may be mounted off the robot for weight savings. A four pole Anderson Power Pole connector and a hose will make this a very simple connection using the robot battery and satisfying the rules.

Re: Off robot air compressor
 

Al, I agree with your reasoning and believe that your interpretation (above) is consistent with the spirit and goals of the rules. However, the letter of the rules may be a different matter. <R101> is pretty explicit: Taken literally I think this says that everything except the compressor must be on the robot and configured to comply with all the rules, just as it would have been in the case of an on-board compressor. That would include the pressure switch and the Spike relay.

EDIT: It is worth posting a question on FIRST Q&A to get this clarified. To repeat: I think Al's interpretation makes sense.

Re: Off robot air compressor
 

If we were dealing with a particularly volatile system, operating near its failure point, that would be an entirely reasonable precaution. However, the AVT-32-16 tanks, as supplied, have a rated pressure of 250 psi, and certainly a safety factor on top of that. The kit compressor can't physically sustain much more than 130 psi at 12 V without risking overheating (it may even have a thermal cutoff), and has an integral relief valve that restricts its upper limit anyway. There are pressure gauges to indicate the pressure in the system to anyone interested. Why must all of these safety features be additionally backed up by programmatic control which can be easily defeated in non-obvious ways—if anything, shouldn't the pressure switch be used to directly override the Spike's input signal from the RC*, rather than relying upon lines of code which can be removed by accident?

Basically, it seems like overkill, and it feels like wasted effort to protect a system which is already far more fail-safe than most of the robot.

*Don't do this. It's a violation of the rules. You must program the RC to accept a signal from the pressure switch over one of the digital inputs. Worse still, don't even think about wiring the pressure switch on the compressor's power lines.

Re: Off robot air compressor
 

I say this every year but I'll say it again. Put a pressure relief valve on the robot and I know that the team hasn't overpressureized with an on board compresser. You have one on the compressor and one on the accumulator to prevent someone from trying to charge into a closed valve and you're done. Do this and it becomes impossible to overpressurize any leg of the system. The additional parts of the pressure switch etc. could be on or off board and wired the same, but if teams actually had to have a pressure relief valve on board I would actually believe none of them tried to overpressurize.

Also most Thomas of this size have a thermal overload, so I would expect the kit one to as well.

Re: Off robot air compressor
 

At the Thomas site (with some digging) you can find a .pdf datasheet for the 405ADC38/12 compressor. Its motor is rated for 12V, 10.5A continuous duty. It is thermally protected, which means that it will turn itself off before overheating. Rated current draw at stall is 25A, so presumably it will self-protect when stalled long enough to get hot. Rated pressure is 100 PSI continuously, and rated ambient temperature range is 50 deg F minimum to 104 deg F maximum.

All this supports what Tristan is arguing above -- the FRC rules for pneumatics provide multiple levels of safety. Possibly more levels than are really needed, but I'm comfortable leaving that to the GDC. The pneumatics rules as written are not hard to understand or police, except that I still think Al's suggestion above regarding configuration of components for use with an off-board compressor is very sensible. I would like to get a Q&A response on that.

Re: Off robot air compressor
 

The same result may be achieved with a properly installed popoff valve which is already required, whether the compressor is mounted or not. I still don't see a valid engineering reason for requiring compressed air from one source over another.

I also do not see how it is enforcable as when the robot lines up in the que I have no idea just where the air on board came from. Yes, they had the required compressor set-up in the pit, but did they actually use it? or did they use something else? How would I tell the difference?

In the past this has been a minor issue. Only a couple of teams at an event would use an off-board compressor. But this year there are more applications where pnuematics are a good fit to the task AND we have twice the storage capacity. So teams like mine that in previous years figured that there wasn't enough storage capacity to ensure the shifters kept working the entire match will be taking another look at doing this.

If it was shown that the onboard system in the authorized configuration could not generate enough pressure to actually blow the popoff, that the popoff was actually there to protect against over pressures caused by mechanical action like forcing a cylinder in a direction it didn't want to go, then I would feel much more comfortable with this rule. Or FIRST could enact a rule prohibiting non-FIRST compressors or air storage devices in the competition area. Until then I will continue to dislike this particular rule, which is not to say I won't enforce it.

Re: Off robot air compressor
 

I still stand firm on my belief that compressed air is compressed air no matter how it is compressed, and that should the rules allow it, any team putting compressed air into their tanks would do so with a compressor that is manufactured by a professional company that does not put out more than 125 psi. I don't think anyone is going to bring their rusted out compressor, or engine driven compressor, or 5 HP compressor.

I think after the completion of a season, there should be a "petition for change of rules" forum/form submission/etc for the next year, done in a very formal and controlled manner by the mentor of each team who wishes to participate.

Anyhow, moving on.

On the topic of the pressure switch, as an inspector, I saw numerous teams without one at the regional. They didn't even know what it was or how to program it. No one had an extra. What were we supposed to do? Render their pneumatic system un-usable because it is missing the switch? Or (per the manual) not allow them to place their robot on the field because it was missing a (trivial) required part? They payed big bucks to field a robot (just like everyone else), so, that they did, and there were no problems. I guess what I'm saying is, we don't like the some of the rules, but lets get the word out anyhow so we can deal with them sooner rather than later.

Teams. Please install and program the pressure switch and wire and control the compressor by the rules regardless of whether it is on your robot or not.

And on my above note, I suppose we are expected to have a Spike relay on the robot, to control a compressor off the robot? I'd rather run out there with a pre-charged two gallon tank and go "pssh, pop" (about a 1.5 second process) than sit there and fiddle around with wires and whatnot waiting for it to finish going "brrmmmmmmmmmm" for a half mintue or so. Pneumatic systems leak. This is FRC, nothing is perfect. We'd like to be able to fill our tanks right on the field. But we don't want to hold up the event by waiting for the incredibly low CFM compressor to do it, especially now that we have 4 tanks.

Re: Off robot air compressor
 

This rule isn't very good for us. Our cart has a built in compressor (The one included with the kit of parts from last year) and it has the pressure switch connected to a relay, not a spike, that is switched on and off with a 30 AMP switch connected to the same type of breaker panel with a 20 AMP Auto-reset breaker that was also included in the kit last year. We basically got all the parts from last year's kit of parts except for the relay that we got at our local Radio Shack. Basically, this system is just as safe as the RC controlled setup, so why must FIRST make us hook up a controller just to control a compressor. If they make certain guidelines such as "If a compressor is used off the robot to charge the pneumatics, it must be controlled by the included pressure switch and must be fused using a 20 AMP fuse with the correct gauge wire."

EDIT: I guess one good thing about the off board compressor is that we can use the old batteries, unless they change that as well...

Re: Off robot air compressor
 

This is one of the most heated items of the robot build over the last few years. Many people have brought up safety and related issues and a variety of other topics of what might be and what could be and what might fail. So, as an inspector and someone who has used both high and low pressure air supply for a variety of different tasks here are some things to consider...
I have seen injuries caused by failures of tubing due to over pressure, I have seen pressure regulators fail as open circuit, dumping high side pressure directly into the system. I have seen hoses flailing through the air under pressure, one actually knocking over a production line. I have found pressure relief valves that fail to open and pressure vessels that fail for any of a number of reasons. I have, as inspector, seen teams who thought it was OK to plug the compressor directly to a battery and watch the pressure guage and yank the power when they thought it was the right time. I have come across at least one team who had a car battery in their compressor rig with a switch and nothing else (breakers or fuses and certainly no pressure control). I have seen teams bring the 1/2 horsepower compressor out of their garage (capable of powering air tools) with a 2-1/2 gallon tank, to fill their robot and used the exhaust valve to regulate the pressure applied to the system. I have seen teams who didn't know how to plumb in the pressure guage and so left it off, same for the pressure exhaust valve. I have seen teams who did not know how to terminate tubing or to know that it was securely seated in the fittings. All of this and I am not even mentioning the use of pistons in dangerous ways. In fairness, I have seen equally destructive practices on mechanical systems and electrical systems. That is why we inspect.
Nasa is an organization that "backs up the back up" as so many others where safety is concerned. In this case, the pressure switch and RC/spike combination is backed up by the pressure relief valve on the compressor which in turn is backed up by the inspection team performing a check that all works as normal. So with these experiences in mind I do not see the rules for compressor use on or off the robot as excessive.

Re: Off robot air compressor
 

Al, that last post covers the topic very well.

I only want to add, for the benefit of those who may not have met Al at an FRC event yet, that he is one of the most experienced and graciously professional volunteers associated with FIRST. The view that he expresses above is directly in line with the stated intention of FIRST, reinforced by increased support in recent seasons, to make safety the top priority.

Because of this am confident that the off-robot compressor rules (conservative as they may be) will be applied as written at all 2007 FRC events. All teams should plan and design their robots accordingly.

Re: Off robot air compressor
 

"Render their pneumatic system un-usable because it is missing the switch?" "...not allow them to place their robot on the field...?" Yes, that is exactly what you should have done.** Why? Because that is what the rules demand. As an inspector, you have agreed to enforce the rules as written and not make up your own. You may or may not agree with the rules. But the simple fact is that you are there to enforce the rules that are in place, and that every team expects to be enforced. If you cannot or will not do that, then you should not be an inspector.

What about the team that fully complied with all the rules (as the vast majority of teams do), and went to considerable lengths to make sure that our robot was in full compliance, and had to compete against the team that you let slide through? They paid the same big bucks to put a legal robot on the field, and they expect every one of their competitors to do the same. If the rules-skirting team beat the rules-following team, did they really win? The rules-following team would have every right to be furious about the fact that you let a robot in violation of the rules out on the field to compete, and potentially knock them out of the competition.

Every year we get lots of folks whining and complaining about FIRST's "soft enforcement" of the rules on and off the field. Yet we only have to look to ourselves to see how it happens. In the great majority of cases, we - the members of the FIRST community - are the referees, inspectors, judges, and volunteers that are there to enforce the rules. But we keep coming up with endless reasons why this rule isn't fair or that rule isn't practical, and give permission to ourselves or others to violate them. And the end of that process is a rule book that is meaningless, professional behavior is thrown out the window, and a "win at all costs" mentality takes over everything. In other words, it becomes pro wrestling.

If we expect the rules to have any meaning, and if we expect the teams to pay attention to the rules so that we can have a fair and even competition, then we have to be the first ones to recognize and abide by them. That is true in every aspect of the competition - whether we are acting as mentors, competitors, judges, inspectors, referees, mechanics, or just members of the audience.

-dave

** and when you are finished, you should go to every effort that you can to help them locate the missing part, and get it plumbed into their pneumatic system so they can pass a real inspection and legally get out on the field and compete in full compliance with the rules.

Re: Off robot air compressor
 

So, Al, I imagine it would be a bit awkward to connect and disconnect the compressor lead wires to and from the Spike Relay on the robot every time a team wants to charge up their system. If a team mounted a suitable 2-way quick disconnect connector (like the red Anderson connectors only not nearly as beefy) somewhere convenient near the periphery of the robot and ran red and black pigtail leads back from the connector to the Spike, would that be a legal setup? Just curious. 48 hasn't used pneumatics since 2003, and I haven't had the opportunity to observe how teams with offboard pumps legally charge up their systems.

If the quick connector were legal, along with the air line from the pump, which would plug into the manual dump valve mounted to the accumulator, you'd have one power and one air connection. Plug in, open the valve, turn the robot on, charge up to full pressure, close the valve, power down the robot, remove the pump, and you're done. Correct?

Re: Off robot air compressor
 

Exactly. It is that easy to use, and it is that easy to implement and be completely within the rules.

-dave

Re: Off robot air compressor
 

T,
The Anderson people make connectors for #10 wire that are small and the shells snap together to form as many contacts as you want and come in a vareity of colors. They are also available through the usual sources, Terminal Supply and Powerex. We have used them for years to make our robot modular. As to the rest of your post, YES. Tether, connect pump electrical and hose, open the exhaust valve, power the robot, wait until the pump is shut off under RC control, close the exhaust valve, shut down the robot and disconnect the electrical and hose from the outboard compressor. Check the pressure guage to make sure you are at no more than 125 PSI and go win a match.

Re: Off robot air compressor
 

That's exactly what the TechnoKats did for the 2006 'bot, right down to the color of wires and brand of connector.

We also had a 2005 OI with a spare tether cable mounted to the frame holding the off-board compressor, so we didn't need to connect the "real" OI in order to get the robot to power up and run the compressor. The compressor frame had a spot to carry a battery as well; the drive team would charge up the pneumatics using the "pit" battery and quickly swap in a fully-charged "competition" battery.