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-   -   Pre-filling stored air (http://www.chiefdelphi.com/forums/showthread.php?t=154618)

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.


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