Using Second battery to Charge Tanks

[wilsonmw04]

Originally Posted by Mark McLeod

I'm rooting for your students.

As am I. They are a great group of kids.

Dude, just saw you'll be at VCU in a week. I'll look you up. It will be nice to match a face to a CD tag.

[Mark McLeod]

Originally Posted by wilsonmw04

As am I. They are a great group of kids.

Dude, just saw you'll be at VCU in a week. I'll look you up. It will be nice to match a face to a CD tag.

Your honorable stance teaches them all they need to know to have a successful and fulfilling life.

I'm a mentor with team 2402 from Fredericksburg. I'm older than my photo appears (my hair is graying now) -that was taken more than 10 years ago.
I get around...

Go Rams!

[Mr. Van]

So... has anyone come to a conclusion on this issue?

It is very clear that the robot must be controlling the compressor when it is filling the tanks - on board or not.

There is a very interesting question regarding switching the battery after the compression is complete. For many robots this is not a real "game changer", but at least one example that's been mentioned on these forums is a robot that requires 7 minutes to compress its tanks!

This is roughly about 40% of the total energy output from the battery in the duration of a match.

Yes, it is legal to store this much energy in springs on the robot, but there is no rule saying that "springs must be stretched/compressed under the control of the ROBOT".

It seems to me that the answer to this question could indeed be a "game changer" in certain circumstances.

When does a robot become the ROBOT?

-Mr. Van
Coach, Robodox

[Mark McLeod]

To have the force of a rule there must be a clear interpretation from the GDC and uniform "enforcement" across all events. That's the rule "rule."

I don't mean "enforcement" in the sense that an authority such as the Lead Inspector must stand over us. It's on the honor system. We all want to do the right thing.
I just mean that the event authority (and in this case it would be the Lead Robot Inspector's responsibility) makes it clear that's how the rule will be read.

Since, teams have done this for year's under essentially the same rule set, I think it's a stretch to say this is a rule, much less a uniform interpretation.
From their Q&A response and actions, or lack thereof, I don't believe that the GDC agrees with this particular interpretation.
The Q&A response seemed to be that there was obviously no such rule limiting when the battery can be changed.

I think we are all leaving with the same interpretation that we came in with...
There is no way to prove an anti-rule.

[Joe Ross]

Do teams with onboard compressors vent their pneumatic system every time they change batteries?

[Racer26]

Originally Posted by scottydoh

You seem to be missing the point here.

Its makes the inspection process 10x easier. If every team has to provide spec sheets proving that their non KoP compressor meets the required specs, you can be certain that there will be many more problems/headaches for teams. FIRST says this is a rule, so just accept that fact. I had to help at least 2 teams reconfigure their pneumatic system simply because they didn't read the rules this past Thursday.

I'm not missing any point. FIRST has said right in the rule book this year, that any compressor meeting those requirements is legal. That means that any team using a non-KOP compressor has to prove this anyway.

Consider: Hypothetical robot RedABot has an offboard compressor, powered and controlled by the ROBOT battery per the current rules. RedABot has some onboard air tanks for storage. RedABot fills its tanks to ~120psi, the compressor shuts off via sensors and is disconnected, the battery is switched, and then RedABot is placed on the field.

Hypothetical robot BlueABot is identical to RedABot in every way. BlueABot also has an offboard compressor, non-KOP, much higher flow-rate, powered and controlled by some external system. BlueABot fills its tanks to ~120psi, the compressor shuts off via sensors and is disconnected, battery switched, and BlueABot is placed on the field.

At the start of the MATCH (after the MC counts down), how are RedABot and BlueABot different? Does BlueABot have a competitive advantage? Why? Was BlueABot any LESS safe in its method of reaching this point?

Telling teams that their off-board compressor must still be powered by the ROBOT battery and controlled by the ROBOT's CONTROL SYSTEM doesn't simplify inspections, it makes them more complex. The simplest inspection of the control of the compressor, is does it turn on, and pressurize the system to 120psi, then shut off. If yes, all is well. Also, it means that instead of a simple air hose connection on the end of the dump valve, teams need to also create some method of attaching power and signal wires to their off-board compressor from the PDB and sidecar. It makes the whole system needlessly complicated.

EDIT: Also, I STRONGLY disagree with your statement of "FIRST says its a rule, so just accept that fact." This program is all about nurturing young minds to solve problems, and become the best they can be. The program is FAR from perfect, and there are lots of ways for it to improve. Also, asking WHY is ALWAYS an EXCELLENT way to learn things. Asking WHY something is done a particular way always leads to learning. Often, there's something more than meets the eye. There could be consequences of not doing things a certain way that you don't think of. Alternatively, the people you're asking may not have thought of your solution, and they'll learn from you. I never accept "because I said so" as an answer. There is ALWAYS an underlying reason, even if its not immediately obvious.

[scottydoh]

I don't understand why we're still arguing this. If everyone really had this much of a problem with the rule, then someone should contact FIRST.

[wilsonmw04]

Originally Posted by scottydoh

I don't understand why we're still arguing this. If everyone really had this much of a problem with the rule, then someone should contact FIRST.

Someone has (please see OP). GDC is still ambiguous since R69 does not specify or pertain to robot battery changes.

Q & A will be asked again soon, but i'm not sure that the answer will be any different than was already stated.

[Alan Anderson]

Originally Posted by 1075guy

Telling teams that their off-board compressor must still be powered by the ROBOT battery and controlled by the ROBOT's CONTROL SYSTEM doesn't simplify inspections, it makes them more complex.

Under the existing rules, every robot's pneumatic system works the same. The robot powers and controls the compressor. That's a specific level of complexity that the inspectors must deal with. The only difference with an off-board compressor is simply that the compressor itself is not mounted on the robot.

Under your preferred relaxation of the rules, teams could have different methods for pressurizing their system. That would make inspections more complex. I won't detail all the things I can think of, but there would have to be some major changes to the pneumatic system rules in order to accommodate less restricted off-board sources of compressed air without adding significant burden to the inspection process.

[Matt Krass]

Originally Posted by Mark McLeod

Your honorable stance teaches them all they need to know to have a successful and fulfilling life.

I'm a mentor with team 2402 from Fredericksburg. I'm older than my photo appears (my hair is graying now) -that was taken more than 10 years ago.
I get around...

Go Rams!

He's lying, his hair isn't graying, its gray

I believe the intention of the ruling is to make sure the pneumatics are charged and controlled under the same rules and conditions (and safety systems) any other robot with the compressor on-board would have. This makes sense, and while cumbersome, I can understand it.

However I fail to see any way in which using a separate 'practice' robot battery bypasses any of those particular intended restrictions, or otherwise gives you an advantage or presents a danger, and thus I would have interpreted the ruling to allow you to swap your battery between charging the pneumatics and competing on the field.

That said, I'm only me, and my name isn't nearly popular enough to sway inspectors or refs ask the GDC for this exact situation. I believe they will rule in your favor, but having it confirmed can help everyone rest easier.

Matt

[Travis Hoffman]

Originally Posted by Matt Krass

I believe they will rule in your favor...

Famous last words?

[1708xMr.Roboto]

Team 1708 did this in Washington DC this year,

after our First regional we ended up dumping the compressor and the Clippard tanks, for some of the lighter PVC tanks so we could include a mini bot launcher on our robot. The way our system worked was like this, we had a onboard Spike and when the tanks needed charged (Between Matches) we plugged in the compressor to the spike, and ran the compressor off the robot's battery. You are allowed to do so, as long as you can prove that your compressor and code shut off at 120psi. after that was all said and done, we switched the robot's battery and were ready to rock and roll. This made being in the Finals interesting considering it took about 4 and a half minutes to fill the tanks; and we only had 6 minutes between matches

-1708

[MikeE]

Let's try a different tack.

Here is the FRC prime directive:

<R01> Energy used by FRC ROBOTS, (i.e., stored at the start of a MATCH), shall come only from the following sources:
A. Electrical energy derived from the onboard 12V battery (see Rule <R34> for specifications and further details).
B. Compressed air stored in the pneumatic system, stored at a maximum pressure of 120 PSI.
C. A change in the altitude of the ROBOT center of gravity.
D. Storage achieved by deformation of ROBOT parts.

Note that <R01> doesn't say energy can only come from one of these sources, but "from the following sources", so it's clear that they can be used in combination.
Some energy for running the cRIO, motors, etc during the match comes from the onboard 12V battery per <R01>.A
Other energy may come from stored compressed air per <R01>.B
Rule <R69> further restricts the earlier source of this energy to a 12V battery, but doesn't expressly state that it must be the same as that of <R01>.A

[Al Skierkiewicz]

MikeE,
Your response is the defining start of the compressor rules. Those rules that pertain to off board compressors are not meant to give you an advantage over other teams on the field that do not have an off board compressor. To meet R01 while allowing off board compressors, there needed to be some massaging of the rules. The give and take for off board is reduction in robot weight for a limited air capacity. That is all. Those teams with the compressor on the robot must control it from the Crio and so too should off board compressors. On board uses the robot battery and so should off board. There can be no advantage given in either case. While the current rules do not bring robot battery into the equation, teams with on board compressors can pre-charge their pneumatics and then change batteries prior to taking the field. That being said, the same can hold true for off board. Personally, I would like to see a rule allowing only one battery per match. There are many teams that are on the edge of efficient design that are depleting a battery in a single match. If we are trying to inspire, this is one area we have fallen down on the job.
However, with the variety of pneumatic designs we see, I am always fearful of teams in the queue with pre-charged pneumatics.

Mark,
It's time for a new picture.

[wilsonmw04]

Originally Posted by Al Skierkiewicz

MikeE,

However, with the variety of pneumatic designs we see, I am always fearful of teams in the queue with pre-charged pneumatics.

Mark,
It's time for a new picture.

I completely agree with this statement. When you consider the unlimited air supply one can have this year, re-charging is even more advantageous. Maybe we could have a staging area before the match where teams can prep/charge or whatever they need to do to be ready to play. It could be the queuing boxes that you stand in while waiting for the match in front of you to play out. 5 minutes should be more than enough time to prep a robot for play. Could you imagine a kicker from last year extending in the tightly packed group that is a queuing line?