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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 |
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.
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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.
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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
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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.
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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?
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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. |
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.
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RTM ::rtm::
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:rolleyes: :rolleyes: :rolleyes: |
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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.
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I second this notion. Even though its not going to happen this year. *crosses fingers*
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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. |
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I'll +4 |
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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. |
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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. |
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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.
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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. |
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Re-posting the stored energy rule: Quote:
Comparing the language between the pertient rules makes the answer obvious in my opinion. Quote:
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I will bet $1 that this is how FIRST intends the rules to be interpreted. |
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Field air would be a dream come true for off board compressor teams. |
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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. |
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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. |
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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. |
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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. |
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