Using Second battery to Charge Tanks

[wilsonmw04]

Greetings,

After reading a "what do you do in between matches" tread, it seems like it is common practice for some teams to charge their air tanks with one battery, then swap out a fresh battery before heading to the field.


I have seen one post on the Q&A on this topic:

Question: Can the air tanks on the robot be pre-charged with air before entering the arena? If so can they be charged with a seperate power source than the battery used in the match?

Reply: Review R69 and Blue Box in the manual.

Here is R69 and the Blue Box:

<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.

If an alternative compressor is used, the team may be required to provide documentation to show compliance with the performance specifications.
The only difference between an on- and off-board compressor is that the off-board compressor is physically removed from the ROBOT. The intent of this rule is to permit teams to take advantage of the weight savings associated with keeping the compressor off-board. However, using the compressor off-board of the ROBOT does NOT permit non-compliance with any other applicable rules.
The compressor may be mounted on the ROBOT, or it may be left off the ROBOT and used to pre-charge compressed air in the storage tanks prior to bringing the ROBOT onto the FIELD.

So, is it legal?
I read this as one compressor and one battery mounted on your robot. Therefore, it would be illegal to change the battery after the tanks have been charged.

Am I reading the rule correctly?

[jwfoss]

Use battery one to charge the robot up, making sure that it is the robot controlling the compressor, not just hard wired or an external switch.

Turn robot off.

Remove battery and replace with a fresh battery two.

Go to field and compete.

[wilsonmw04]

Originally Posted by jwfoss

Use battery one to charge the robot up, making sure that it is the robot controlling the compressor, not just hard wired or an external switch.

Turn robot off.

Remove battery and replace with a fresh battery two.

Go to field and compete.

I understand that's how it's done, but is it legal?

A robot is one compressor and 1 battery. By using two batteries you are effectively using more "electrical energy" than is available in one battery. This is what I am questioning.
When I was asking about off board compression, I was told we had to use the same battery as we would use in the match. Why is keeping the compressor on the robot given an exemption to that rule?

[Mark McLeod]

Originally Posted by wilsonmw04

When I was asking about off board compression, I was told we had to use the same battery as we would use in the match. Why is keeping the compressor on the robot given an exemption to that rule?

I assume you asked the GDC in a Q&A not some random volunteer.
Remember, even answers from the Lead Robot Inspector may change as the season progresses and they all come to a common rules interpretation.
I don't recall any such Q&A though.

I think your issue here is how the question is framed and (presumably answered by the GDC).

The answer you received appears to simply be addressing the issue that the compressor must be powered through the robot by the robot battery whenever it is operated, not that batteries cannot be changed.

The robot can only be powered by a single battery while in a match.
A match doesn't begin in the pit or on the queue or in a previous on-field appearance where pressure wasn't releaved afterwards.
A match begins when the field sounds.

[wilsonmw04]

Originally Posted by Mark McLeod

I assume you asked the GDC in a Q&A not some random volunteer.
I don't recall any such Q&A though.

I think your issue here is how the question is framed and (presumably answered by the GDC).

The answer you received appears to simply be addressing the issue that the compressor must be powered through the robot by the robot battery whenever it is operated.

And that is the question I think is core to my problem. When does the robot become the robot?
From my POV once you use the battery to compress air in your tanks, that battery becomes part of the robot for that match. If you removed the battery after the compression, you are using two batteries for a match.

Mark,
The question regarding swapping batteries was asked in the Q & A and they directed the petitioner to R69. I'm just not sure how that answers the question.

[Mark McLeod]

Originally Posted by wilsonmw04

From my POV once you use the battery to compress air in your tanks, that battery becomes part of the robot for that match. If you removed the battery after the compression, you are using two batteries for a match.

Then I posit that you cannot change your battery after you have used the energy to download any code that will be used in said match.

[wilsonmw04]

Originally Posted by Mark McLeod

Then I posit that you cannot change your battery after you have used the energy to download any code that will be used in said match.

I would disagree because changing code does not store anything that could do work for the robot.
Thanks for being lighthearted about this. This is not a hypothetical for my team. With such a large set of tanks this year, it take over one minute to charge our system. If we could do that with another battery it could be a substantial advantage for the team. I just don't see how it jives with the rules. I know others do it; the GDC is rather vague on the issue. I just don't like gray areas. It get's folk in trouble and feelings hurt.

[BigJ]

Originally Posted by Mark McLeod

Then I posit that you cannot change your battery after you have used the energy to download any code that will be used in said match.

Probably should just use the same battery you used to image the cRIO last.

[Mark McLeod]

I don't believe any rule supports your self-imposed position.
I don't beleve the GDC supports your position, otherwise, they would say so.

I believe only one battery can be used during a match.
A match begins with the field sound and ends with the refs all clear flag.
(it doesn't end with a field sound this season).

I don't accept the stored energy argument (even without the evidence of a rule), otherwise, springs, elastic tubing and other potential energy storage is also suspect. Thereby excluding human muscle power from the robot, as well, if the battery is the sole source of energy.

My beliefs don't constrain the GDC, but are what I will advise any team that asks.

I'm rooting for your students.

[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

[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]

As long as the "practice" battery is connected to the robot's electrical system via the red Anderson connector, and the compressor is connected to a Spike relay on the robot, then yes, you can use the practice battery to charge the air tanks and then swap in a fresh "match" battery before heading to the field.

If you powered the compressor DIRECTLY from the practice battery, bypassing the robot's control system entirely, that would not be permitted.

Originally Posted by wilsonmw04

Greetings,

After reading a "what do you do in between matches" tread, it seems like it is common practice for some teams to charge their air tanks with one battery, then swap out a fresh battery before heading to the field.


I have seen one post on the Q&A on this topic:



Here is R69 and the Blue Box:




So, is it legal?
I read this as one compressor and one battery mounted on your robot. Therefore, it would be illegal to change the battery after the tanks have been charged.

Am I reading the rule correctly?

[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.