Off robot air compressor

[Billfred]

Originally Posted by Kirk

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.

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.

[Al Skierkiewicz]

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).

[Kirk]

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?

[Alan Anderson]

Originally Posted by Billfred

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.

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.)

[Al Skierkiewicz]

Originally Posted by Kirk

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?

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.

[Dave Flowerday]

Originally Posted by Al Skierkiewicz

These rules are the same as previous years.

Not according to the "2006 FIRST Welcome to Robotics Inspection Rev D" document on FIRST's website. Under "What's New for 2006":

10) If the robot uses an off-robot compressor for pre-charging the pneumatic tanks the robot (either 1 or 2 Clippard Instrument tanks), the team must use the KOP Thomas air compressor through a 20A breaker and Spike Relay Module (with fuse replaced by 20A Snap Action breaker if desired). The team is required the Robot Controller and Nason Pressure Switch to control the process.

Earlier in the same document, there is this statement:

47) If the robot uses an off-robot compressor for pre-charging the pneumatic tanks on the robot (either 1 or 2 Clippard Instrument tanks), the team must use the KOP Thomas air compressor through a 20A breaker and Spike Relay Module (with fuse replaced by 20A Snap Action breaker if desired). The team is not required to use the Robot Controller and/or Nason Pressure Switch and/or circuit breaker panels to control the process.

(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...

[KenWittlief]

Originally Posted by Dave Flowerday

Not according to the "2006 FIRST Welcome to Robotics Inspection Rev D" document on FIRST's website. Under "What's New for 2006":
...

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.

[Dave Flowerday]

Originally Posted by KenWittlief

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.

Yes, I know, and that document is not a rules document anyway. At any rate, it has been clarified by FIRST:

Originally Posted by GDC Q&A

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>.

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.

[Richard Wallace]

Originally Posted by KenWittlief

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.

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

[Russ Beavis]

Originally Posted by Dave Flowerday

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...

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

[Richard Wallace]

Originally Posted by Dave Flowerday

... 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.

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.

[Dave Flowerday]

Originally Posted by Richard

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.

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}

[Richard Wallace]

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.

[Travis Covington]

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.

[Ed Sparks]

Originally Posted by Travis Covington

....... all of the requirements for the spike, RC, pressure switch, OI, etc seem redundant.

..... 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.....

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

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 .......