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FRCTeam2906 02-02-2017 12:53

Pre-filling stored air
 
We are looking at having alot of tanks on our bot this year. Can we fill our tanks before tbe match? We are hoping to complete this by using an external battery to power our on board compresser, then plug it back into the pcm (we are connecting it with anderson connectors). Is this legal or should we ask the q&a?

Let us know,
FRC Team 2906

Sparky3D 02-02-2017 13:03

Re: Pre-filling stored air
 
You can pre-fill your tanks, but not by bypassing the control system like you proposed. Just connect your robot to your driver station via ethernet cable in your pit, enable the robot until the compressor shuts off, then put in a fresh battery. Just make sure you aren't set to run autonomous when you enable.

jSchnitz 02-02-2017 13:03

Re: Pre-filling stored air
 
That definitely isn't legal by R85. You can only power the compressor through the robot control system. If you have an onboard compressor you can just enable your bot in queue, though.

Nessie 02-02-2017 13:04

Re: Pre-filling stored air
 
Quote:

Originally Posted by FRCTeam2906 (Post 1639484)
We are looking at having alot of tanks on our bot this year. Can we fill our tanks before tbe match? We are hoping to complete this by using an external battery to power our on board compresser, then plug it back into the pcm (we are connecting it with anderson connectors). Is this legal or should we ask the q&a?

Let us know,
FRC Team 2906

I don't see the need for the off-board complications. Fill your air system normally then swap in a fresh battery.

orangemoore 02-02-2017 13:06

Re: Pre-filling stored air
 
You cannot bypass the control system to use the compressor like others have stated but is legal to use a different battery and pre-charge your air tanks

rich2202 02-02-2017 13:09

Re: Pre-filling stored air
 
Also R84 "one and only one compressor". If you have a compressor on the robot, then that is the only compressor you can use, including pre-fill.

flemdogmillion 02-02-2017 14:40

Re: Pre-filling stored air
 
What about a bike pump / foot pump and a schrader fitting? can that be used to fill the tank in queue rather than enabling the robot?

cgmv123 02-02-2017 14:44

Re: Pre-filling stored air
 
Quote:

Originally Posted by flemdogmillion (Post 1639550)
What about a bike pump / foot pump and a schrader fitting? can that be used to fill the tank in queue rather than enabling the robot?

That would mean the ROBOT would get compressed air from a source other than the one compressor, which violates R84.

Kevin Sevcik 02-02-2017 14:59

Re: Pre-filling stored air
 
I'd also note that by "another battery" that should be another legal FRC battery, through a standard battery connector, etc.

The whole point of this portion of the pneumatics rules is to mostly limit the stored power on the robot to what's supplied by the ONE legal battery powering the ONE legal compressor. Onboard or offboard compressor, airing up your robot should be exactly like it was running an onboard compressor on the field during a match. Ask yourself if what you're doing is something that'd be legal during a match, minus size/weight constraints for an off-board compressor. If it's not legal during a match, it's not legal in your pit in prep for a match.

This means you should think about your air consumption and how well your system would work with a 6 minute field timeout between Finals matches. If you can't fill your tanks from empty or end of match level to full enough in 5 minutes, you're using too much air.

Al Skierkiewicz 02-02-2017 15:12

Re: Pre-filling stored air
 
As others have stated, charging your pneumatic system with anything other than that provided by the rules could result in any decision by event Chief volunteers. If stored air is important to your strategy then do not risk it by charging your system by any method other than that provided in the robot rules.

JamesCH95 02-02-2017 16:02

Re: Pre-filling stored air
 
RTM ::rtm::

Quote:

R43. Non-electrical sources of energy used by the ROBOT, (i.e., stored at the start of a MATCH), shall
come only from the following sources:
A. compressed air stored in the pneumatic system that has been charged in compliance
with R84 and R85,

B. a change in the altitude of the ROBOT center of gravity,
C. storage achieved by deformation of ROBOT parts,
D. closed-loop COTS pneumatic (gas) shocks, and
E. air-filled (pneumatic) wheels.
Quote:

R84. Compressed air on the ROBOT must be provided by one and only one compressor. Compressor
specifications must not exceed nominal 1.10 cfm (~519 cm3/s) flow rate @ 12VDC.
R85. The compressor (permitted per R84) may be located off-board the ROBOT, however the
compressor must still be controlled and powered by the ROBOT when used.
Code:

The compressor may be mounted on the ROBOT, or it may be left off the
ROBOT and used to pre-charge compressed air in storage tanks on the
ROBOT provided the additional restrictions of R90 are met.
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 noncompliance
with any other applicable rules.


Rules are unambiguous on this topic.

DonRotolo 02-02-2017 20:00

Re: Pre-filling stored air
 
Quote:

Originally Posted by JamesCH95 (Post 1639596)
Rules are unambiguous on this topic.

I think "one and only one compressor" is ambiguous and so we're going to use 3 or 4 of them. And a foot pump.

:rolleyes: :rolleyes: :rolleyes:

ctt956 02-02-2017 20:09

Re: Pre-filling stored air
 
Quote:

Originally Posted by orangemoore (Post 1639500)
You cannot bypass the control system to use the compressor like others have stated but is legal to use a different battery and pre-charge your air tanks

You can only use a different legal battery if it is the only battery in the robot, powering it as it would be during a match. As others have said, this should be done before you swap batteries.

Cory 02-02-2017 21:52

Re: Pre-filling stored air
 
FIRST ought to just supply an air compressor field side at the queue which each team can use to fill their tanks. This would solve what is always a problem every year with teams misunderstanding the rules. Would cost $300 per field.

D_Price 02-02-2017 22:29

Re: Pre-filling stored air
 
I second this notion. Even though its not going to happen this year. *crosses fingers*


Quote:

Originally Posted by Cory (Post 1639721)
FIRST ought to just supply an air compressor field side at the queue which each team can use to fill their tanks. This would solve what is always a problem every year with teams misunderstanding the rules. Would cost $300 per field.


Kevin Sevcik 03-02-2017 00:14

Re: Pre-filling stored air
 
Quote:

Originally Posted by Cory (Post 1639721)
FIRST ought to just supply an air compressor field side at the queue which each team can use to fill their tanks. This would solve what is always a problem every year with teams misunderstanding the rules. Would cost $300 per field.

There's little reason for the 1.1CFM limit on the compressor aside from a conscious choice by the GDC to limit how quickly you can store energy in the form of compressed air. That being the case, you'll see free stored energy available field side about the time the GDC removes the flow limits on robot compressors. I'm not holding my breath for that.

Also, teams misunderstand the bumper rules every year too. It's still unlikely the GDC is going to back off on them because looser bumper rules mean both flimsier bumpers and more teams engineering bumpers for a competitive advantage like wedging.

Mark Sheridan 03-02-2017 00:37

Re: Pre-filling stored air
 
Quote:

Originally Posted by Cory (Post 1639721)
FIRST ought to just supply an air compressor field side at the queue which each team can use to fill their tanks. This would solve what is always a problem every year with teams misunderstanding the rules. Would cost $300 per field.

third

frcguy 03-02-2017 01:27

Quote:

Originally Posted by Cory (Post 1639721)
FIRST ought to just supply an air compressor field side at the queue which each team can use to fill their tanks. This would solve what is always a problem every year with teams misunderstanding the rules. Would cost $300 per field.



I'll +4

Cory 03-02-2017 02:05

Re: Pre-filling stored air
 
Quote:

Originally Posted by Kevin Sevcik (Post 1639754)
There's little reason for the 1.1CFM limit on the compressor aside from a conscious choice by the GDC to limit how quickly you can store energy in the form of compressed air. That being the case, you'll see free stored energy available field side about the time the GDC removes the flow limits on robot compressors. I'm not holding my breath for that.

Also, teams misunderstand the bumper rules every year too. It's still unlikely the GDC is going to back off on them because looser bumper rules mean both flimsier bumpers and more teams engineering bumpers for a competitive advantage like wedging.

I don't see how flow limits are at all relevant to FIRST providing an air charging station. You still have the same flow limits once the match has started. The analogy about bumpers doesn't make any sense. It's nowhere near a comparable situation.

It's currently free energy. You just have to swap batteries to do it. It makes far more sense to just quit all the worrying about shop compressors in the pits and whether teams are using offboard compressors correctly and provide a compressor that every team uses to fill up before the match. Every robot is functionally identical when it is set on the field as it would be currently.

bEdhEd 03-02-2017 02:15

Re: Pre-filling stored air
 
We did this in 2012, and my advice is to make sure that your pneumatic system is as leak free as possible. It is likely that you will run into the situation of a delayed match start or a timeout, and when that happened to us, we made sure to recompress after each delay.

We saw this as an inconvenience and have not opted for an offboard compressor since. This was only done because our 2012 robot was designed to be short enough to hold another robot on top of it, so there was literally no space to place an onboard compressor. Those compressors were bigger than the ones used now if I recall right.

I would only advise doing this if there is absolutely no solution to the issue of space for an onboard compressor.

scaryone 03-02-2017 06:25

Re: Pre-filling stored air
 
Interesting. In '12, our team interpreted that the Robot must be precharged with the battery that the team used for that match. In other words, we couldn't pre-charge, then change the battery because that would, technically, be using two batteries. Seems the language is still the same.

JamesCH95 03-02-2017 06:26

Re: Pre-filling stored air
 
Quote:

Originally Posted by FRCTeam2906 (Post 1639484)
We are looking at having alot of tanks on our bot this year. Can we fill our tanks before tbe match? We are hoping to complete this by using an external battery to power our on board compresser, then plug it back into the pcm (we are connecting it with anderson connectors). Is this legal or should we ask the q&a?

Let us know,
FRC Team 2906

Quote:

Originally Posted by bEdhEd (Post 1639763)
We did this in 2012, and my advice is to make sure that your pneumatic system is as leak free as possible. It is likely that you will run into the situation of a delayed match start or a timeout, and when that happened to us, we made sure to recompress after each delay.

We saw this as an inconvenience and have not opted for an offboard compressor since. This was only done because our 2012 robot was designed to be short enough to hold another robot on top of it, so there was literally no space to place an onboard compressor. Those compressors were bigger than the ones used now if I recall right.

I would only advise doing this if there is absolutely no solution to the issue of space for an onboard compressor.

Generally I agree, but did you miss OP's question?

rich2202 03-02-2017 06:58

Re: Pre-filling stored air
 
Quote:

Originally Posted by scaryone (Post 1639768)
Interesting. In '12, our team interpreted that the Robot must be precharged with the battery that the team used for that match. In other words, we couldn't pre-charge, then change the battery because that would, technically, be using two batteries. Seems the language is still the same.

What rule(s) require pre-charging with the SAME battery?

scaryone 03-02-2017 07:11

Re: Pre-filling stored air
 
R44
The one (1) ROBOT battery, a single pair of Anderson Power Products (or APP) 2-pole SB type.....

If you precharge your air system with a battery, then change out said battery for a fresh one, you are using two batteries (starting the match with more energy than one battery normally holds). This seems like a good Q & A.

JamesCH95 03-02-2017 08:23

Re: Pre-filling stored air
 
Quote:

R44 The one (1) ROBOT battery, a single pair of Anderson Power Products (or APP) 2-pole SB type connectors, the one (1) main 120-amp (120A) circuit breaker (Cooper Bussman P/N: CB185-120), and the one (1) CTR Electronics Power Distribution Panel (PDP, P/N: am-2856, 217-4244, 14-806880) shall be connected with 6 AWG (7 SWG or 16 mm2) wire or larger, with no additional devices or modifications, as shown in Figure 8-8.
R44 specifies (among other things) that only one battery should be connected to the robot at any time. There is no rule that prohibits changing a battery after charging storage tanks.

Re-posting the stored energy rule:

Quote:

R43. Non-electrical sources of energy used by the ROBOT, (i.e., stored at the start of a MATCH), shall
come only from the following sources:
A. compressed air stored in the pneumatic system that has been charged in compliance
with R84 and R85,
B. a change in the altitude of the ROBOT center of gravity,
C. storage achieved by deformation of ROBOT parts,
D. closed-loop COTS pneumatic (gas) shocks, and
E. air-filled (pneumatic) wheels.
There is nothing that says all energy at the start of a match must come from one battery charge. The one battery rule is there so that teams don't try to connect two batteries to the same robot, which is fraught with potential disaster.

Comparing the language between the pertient rules makes the answer obvious in my opinion.

Quote:

R37. The only legal source of electrical energy for the ROBOT during the competition, the ROBOTbattery, must be a non-spillable sealed lead acid (SLA) battery with the following specifications:
If all electrical energy used by the robot comes from a legal battery (of which only one may be connected at a time per R44) you'll be fine. No reference to 'only one battery per match' or 'one and only one battery' or anything along those lines.

As compared to the compressor rules:

Quote:

R84. Compressed air on the ROBOT must be provided by one and only one compressor. Compressor specifications must not exceed nominal 1.10 cfm (~519 cm3/s) flow rate @ 12VDC.

R85. The compressor (permitted per R84) may be located off-board the ROBOT, however the compressor must still be controlled and powered by the ROBOT when used.
...one and only one compressor... powered by the robot. Use only one compressor, powered by the one battery that you're allowed to have on your robot at a time, and you're good. Change the battery after charging if you like, there is no rule against that. (If the compressor is mounted on-board it still must be powered and controlled by the robot.)

I will bet $1 that this is how FIRST intends the rules to be interpreted.

cbale2000 03-02-2017 08:33

Re: Pre-filling stored air
 
Quote:

Originally Posted by JamesCH95 (Post 1639786)
R44 specifies (among other things) that only one battery should be connected to the robot at any time. There is no rule that prohibits changing a battery after charging storage tanks.

Re-posting the stored energy rule:



There is nothing that says all energy at the start of a match must come from one battery charge. The one battery rule is there so that teams don't try to connect two batteries to the same robot, which is fraught with potential disaster.

Comparing the language between the pertient rules makes the answer obvious in my opinion.



If all electrical energy used by the robot comes from a legal battery (of which only one may be connected at a time per R44) you'll be fine. No reference to 'only one battery per match' or 'one and only one battery' or anything along those lines.

As compared to the compressor rules:



...one and only one compressor... powered by the robot. Use only one compressor, powered by the one battery that you're allowed to have on your robot at a time, and you're good. Change the battery after charging if you like, there is no rule against that. (If the compressor is mounted on-board it still must be powered and controlled by the robot.)

I will bet $1 that this is how FIRST intends the rules to be interpreted.

Better hope you never have to replace a compressor with that kind of interpretation. :rolleyes:

Kevin Sevcik 03-02-2017 08:40

Re: Pre-filling stored air
 
Quote:

Originally Posted by Cory (Post 1639762)
I don't see how flow limits are at all relevant to FIRST providing an air charging station. You still have the same flow limits once the match has started. The analogy about bumpers doesn't make any sense. It's nowhere near a comparable situation.

It's currently free energy. You just have to swap batteries to do it. It makes far more sense to just quit all the worrying about shop compressors in the pits and whether teams are using offboard compressors correctly and provide a compressor that every team uses to fill up before the match. Every robot is functionally identical when it is set on the field as it would be currently.

It's not unlimited free energy. There's a definite difference between the amount of air you can compress between finals matches with a 1.1 cfm 12v pump and the amount of air a $300 120v compressor can generate. I'll grant you that's something like 10 standard tanks, but still. Wishing for free compressed air is about like wishing for a bigger battery. It could happen some day, but only when the GDC wants to increase our power budget.

JamesCH95 03-02-2017 08:41

Re: Pre-filling stored air
 
Quote:

Originally Posted by cbale2000 (Post 1639787)
Better hope you never have to replace a compressor with that kind of interpretation. :rolleyes:

If a compressor is replaced, vent all air from the robot at that time, then recharge with the new compressor. All of the stored compressed air will have been supplied by one and only one legal compressor, powered and controlled by the robot. All rules are met, both in spirit and in letter.

martin417 03-02-2017 09:51

Re: Pre-filling stored air
 
Quote:

Originally Posted by Cory (Post 1639721)
FIRST ought to just supply an air compressor field side at the queue which each team can use to fill their tanks. This would solve what is always a problem every year with teams misunderstanding the rules. Would cost $300 per field.

+1

SM987 03-02-2017 11:20

Re: Pre-filling stored air
 
Quote:

Originally Posted by bEdhEd (Post 1639763)
I would only advise doing this if there is absolutely no solution to the issue of space for an onboard compressor.

We're usually more concerned about the performance hit everything else on the robot takes when the compressor kicks on. I can't remember the last year we had an on board compressor.

Field air would be a dream come true for off board compressor teams.

mwmac 03-02-2017 11:28

Re: Pre-filling stored air
 
Quote:

Originally Posted by SM987 (Post 1639860)
We're usually more concerned about the performance hit everything else on the robot takes when the compressor kicks on. I can't remember the last year we had an on board compressor.

Agreed. Would rather trade the weight and volume associated with an onboard compressor toward mechanisms.

Chris is me 03-02-2017 11:30

Re: Pre-filling stored air
 
It has always been legal to charge your air tanks with one battery, switch to a fresh battery, and then go out for a match. I don't see any ambiguity in that rule this year. Pro tip: just use the battery you used in your previous match to charge up your air.

There are numerous reasons to go off-board if you can create the air capacity needed to pull this off. The biggest one is current draw - with all these high power motors, adding another 20A load to your system is that much more current to deal with and that much more voltage to drop. There's also the secondary concerns of weight and space.

Ultimately the only reason to use an onboard compressor is if you don't have space, budget, or weight to use sufficient air tanks for an entire match of air - or if you don't have time to charge your air tank within 5 minutes after a match ends (back to back finals matches).

I'm also in support of field-side air. I am aware it relieves one design constraint to do this and thus isn't zero change to the rules, but that's not a good enough reason to not at least consider it for 2018. That restriction isn't the end of the world to see gone.

AdamHeard 03-02-2017 11:37

Re: Pre-filling stored air
 
Quote:

Originally Posted by Kevin Sevcik (Post 1639789)
It's not unlimited free energy. There's a definite difference between the amount of air you can compress between finals matches with a 1.1 cfm 12v pump and the amount of air a $300 120v compressor can generate. I'll grant you that's something like 10 standard tanks, but still. Wishing for free compressed air is about like wishing for a bigger battery. It could happen some day, but only when the GDC wants to increase our power budget.

The amount of energy in just 5 AH of the Battery is far greater than what can plausibly be stored with air on the robot.

FrankJ 03-02-2017 12:30

Re: Pre-filling stored air
 
Quote:

Originally Posted by AdamHeard (Post 1639865)
The amount of energy in just 5 AH of the Battery is far greater than what can plausibly be stored with air on the robot.

But the explosive decompression of a large air tanks (or a chain of small air tanks.) risks are a lot bigger than a crowbar short of a 5 AH battery. I don't want to be alarmist or go down the rabbit hole of risk analysis, but that is a consideration. Granted you could go back to limiting the volume air air stored.

Kevin Sevcik 03-02-2017 13:50

Re: Pre-filling stored air
 
Quote:

Originally Posted by AdamHeard (Post 1639865)
The amount of energy in just 5 AH of the Battery is far greater than what can plausibly be stored with air on the robot.

The Andymark 1.1 Pump pulls 12A on average from 0-120 psi. So running it for 5 minutes between finals gets you an extra 1 AH stored on your robot that doesn't cost you any current draw during a match. Right now to get that you have to jump through all the compressor hoops and leave your robot running on its old battery for the whole timeout, instead of whatever else you'd do with it. I'm assuming the GDC is aware of all the costs associated with that, and figures that's what you have to pay to get that advantage, because it is an advantage. If you want that for free, someone's going to have to convince the GDC to ease up on that constraint.

As a separate matter, allowing 120V compressors for airing up the robot is just going to add another inspection item, because we'll need to make sure the 120V compressor is regulated down to 120psi so teams don't dump high pressure air into their tanks fast enough to exceed 120psi.

FrankJ 03-02-2017 14:02

Re: Pre-filling stored air
 
Quote:

Originally Posted by Kevin Sevcik (Post 1639939)
As a separate matter, allowing 120V compressors for airing up the robot is just going to add another inspection item, because we'll need to make sure the 120V compressor is regulated down to 120psi so teams don't dump high pressure air into their tanks fast enough to exceed 120psi.

The advantage of a field provided compressor is the max PSI can be controlled. and the electrical load required to run the compressor can be planned for. (One issue with team compressors is that most pits are extremely power limited.)

AdamHeard 03-02-2017 14:09

Re: Pre-filling stored air
 
Quote:

Originally Posted by Kevin Sevcik (Post 1639939)
The Andymark 1.1 Pump pulls 12A on average from 0-120 psi. So running it for 5 minutes between finals gets you an extra 1 AH stored on your robot that doesn't cost you any current draw during a match. Right now to get that you have to jump through all the compressor hoops and leave your robot running on its old battery for the whole timeout, instead of whatever else you'd do with it. I'm assuming the GDC is aware of all the costs associated with that, and figures that's what you have to pay to get that advantage, because it is an advantage. If you want that for free, someone's going to have to convince the GDC to ease up on that constraint.

As a separate matter, allowing 120V compressors for airing up the robot is just going to add another inspection item, because we'll need to make sure the 120V compressor is regulated down to 120psi so teams don't dump high pressure air into their tanks fast enough to exceed 120psi.

Since you do that on a separate battery, it's really no different.

Also the 1Ah works out to be far less than 1 AH (converted to J) of energy to be used for motion since the conversion is so inefficient.

Skyehawk 03-02-2017 19:31

Re: Pre-filling stored air
 
Quote:

Originally Posted by scaryone (Post 1639773)
R44
The one (1) ROBOT battery, a single pair of Anderson Power Products (or APP) 2-pole SB type.....

If you precharge your air system with a battery, then change out said battery for a fresh one, you are using two batteries (starting the match with more energy than one battery normally holds). This seems like a good Q & A.

I also recall this being a rule at some point in time. However if this thread has proven anything (other than a general consensus for field-side air) is rules are always open to interpretation. Part of my recolection may be due to how things were run at the Lake Superior regional for the first two years of its existence, or my being a new team member at the time, or how we as a team operate.

If you are smart about how much air you use, having fully charged batteries, and having a design that doesnt run 6 Cims, a minicim and a compressor at the same time you will be just fine. Simplicity trumps complexity when they are performing the exact same task.

Kevin Sevcik 03-02-2017 19:50

Re: Pre-filling stored air
 
Quote:

Originally Posted by AdamHeard (Post 1639952)
Also the 1Ah works out to be far less than 1 AH (converted to J) of energy to be used for motion since the conversion is so inefficient.

On this I totally agree and I try to explain this to everyone that asks me about using pneumatics. But if you're powering it with a robot battery, it's effectively 1Ah of battery life, so that's the appropriate comparison.


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