Using Second battery to Charge Tanks

[Racer26]

This is one of those rules I've always thought was silly. As long as teams are using the proper safety mechanisms, why does the ROBOT battery have to power the off-board compressor.

I've always seen nearly every team with an off-board compressor charge their system, THEN change the battery immediately before the MATCH.

1075 built a robotic cart years ago (it hasn't been used this year, due to malfunctions we haven't had time to fix). It runs an IFI control system, just like our 2000-2008 robots did, (its actually running the system from our 2004 or 2006 robot), uses Black Jaguars to control its drive motors (they're 24VDC motors), and has a separate 12V system to power the control system, and various 12V components, including lights, music, horns, etc (yes, we know musical carts in pits is a no-no, so we generally don't use it at official competitions). We also built a compressor onto the cart, with all the proper interlocks (pressure switch shutoff, etc) but in recent years have not been allowed to use it to pressurize the robot. (We've still used it for blowing metal filings away, and blowing up trackballs)

It gives absolutely zero competitive advantage, and I don't understand why we're not allowed to use it, since its equally safe.

[scottydoh]

Originally Posted by 1075guy

It gives absolutely zero competitive advantage, and I don't understand why we're not allowed to use it, since its equally safe.

<R69> Compressed air for the pneumatic system on the ROBOT must be provided by one and only one compressor. This compressor may be either the compressor from the KOP, or an equivalent compressor that does not exceed any of the KOP compressor performance specifications (specifically: nominal 12v, 1.03 cfm flow rate, 120psi maximum working pressure). Compressed air shall not come from any other source. Off-board compressors must be controlled and powered by the ROBOT.

This is why. The inspection checklist also specifically says the off board compressor MUST be powered by the ROBOT control system.

Are there other safe way to pressurize the system? Yes. But having everything controlled by the robot control system makes things go much smoother for both team and inspectors.

[Alan Anderson]

Originally Posted by 1075guy

This is one of those rules I've always thought was silly. As long as teams are using the proper safety mechanisms, why does the ROBOT battery have to power the off-board compressor.

It's sort of a second-level requirement. The system providing the pneumatic pressure must be inspected to verify that the pneumatic system of the robot complies with the rules. To make that inspection practical, the compressor must be controlled and powered by the robot. It would not be reasonable to ask inspectors to vet any random pressurization system that a team might choose to use.

[Racer26]

...The ROBOTs are required to have the regulators, and the relief valve regardless of whether the compressor is on or off-board. They're also required to have a High-side gauge. I'm failing to see how the method of getting the pressure there matters. Have the team pressurize the system during inspection using their method of choice, see that the system they're using shuts off when the robot reaches ~120psi (as they already do now) and voila.

Realistically, theres only 3 compressors on the market (at least, widely known to the FRC community), that are legal anyway. Its easy enough to check if the compressor being used is one of those 3 (The old Thomas KOP unit, The Viair 92C (new KOP) and Viair 90C.

Frankly, if the compressor is not physically on the robot, I don't see why it matters what compressor you use. A higher flow rate compressor means it fills faster, but if you're not generating the compressed air during the MATCH, who cares, its not giving you any advantage because you have a finite amount of air storage on the ROBOT.

[scottydoh]

Originally Posted by 1075guy

...The ROBOTs are required to have the regulators, and the relief valve regardless of whether the compressor is on or off-board. They're also required to have a High-side gauge. I'm failing to see how the method of getting the pressure there matters. Have the team pressurize the system during inspection using their method of choice, see that the system they're using shuts off when the robot reaches ~120psi (as they already do now) and voila.

Realistically, theres only 3 compressors on the market (at least, widely known to the FRC community), that are legal anyway. Its easy enough to check if the compressor being used is one of those 3 (The old Thomas KOP unit, The Viair 92C (new KOP) and Viair 90C.

Frankly, if the compressor is not physically on the robot, I don't see why it matters what compressor you use. A higher flow rate compressor means it fills faster, but if you're not generating the compressed air during the MATCH, who cares, its not giving you any advantage because you have a finite amount of air storage on the ROBOT.

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.

[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.