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#1
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Re: Pneumatic Restrictions & Improvments
Magnets,
CGL has stated what the correct interpretation of the rules as written. One compressor is practical as demonstrated by the over whelming number of teams that follow the rule of "one and only one". Spares are allowed as are spare motors of the same type and any item listed on the BOM. If this was not the case then many teams would be exceeding the BOM limit for spending on the robot. Your interpretation of additional compressors being used as ballast appears to be correct though provided the GDC/Q&A agree with you. I suspect their decision may be influenced by the same reasoning that additional CIM motors cannot be used as ballast if they exceed the max number allowed. |
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#2
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Re: Pneumatic Restrictions & Improvments
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I don't have an issue with the rule, and the intent of the rule- as has been outlined by yourself/Q&A. However, the phrasing of this rule was taken to extreme limits at the Groton District Event this year. We were forced to remove our 1 gallon air compressor used for our pneumatic tools from the pit citing this exact rule. I took this ruling to mean we were basically not to be trusted for even having a shop compressor in our pit. The rule does not say you can't have spares, it doesn't say you can't have a shop compressor in your pit- it says you can only fill your robot with one compressor. Just wanted to provide that feedback, as this particular interpretation of the rules is not only completely wrong, it is insulting to a team as you are essentially calling them untrustworthy. -Brando |
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#3
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Re: Pneumatic Restrictions & Improvments
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What pneumatic tools do you use that can't easily be swapped out for a motor-driven equivalent? In my experience working on these robots, there's nothing we can do with a pneumatic tool that we can't do with a motor-based tool. |
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#4
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Re: Pneumatic Restrictions & Improvments
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The biggest reason we bring it is for our pneumatic rivet guns. Many of our modular sub assemblies are mounted purely with rivets, and popping 100+ steel 3/16" rivets with a pneumatic rivet gun is MUCH faster than doing it by hand (and comes out higher quality). We obviously make do with the manual tools, as we've been forced to remove this compressor in the past. However the preference will always be to have it IF we are allowed to. Just to add perspective, this is not a large shop compressor. Its a 1 gallon harbor freight job that would be something akin to what's in the trunk of your car to fix a flat. Regarding not knowing if a team is using to fill their robot- you're 100% right. However, how do you know a team isn't using a spare legal robot compressor to fill their robot? Or breaking one of many other rules? We trust teams and give them the benefit of the doubt on so many levels, it just seems odd that this is the item that pushes us over the edge to where we say a team cannot be trusted. And just to bring this full circle, if a team does need to remove a compressor for one of the reasons you outlined- we shouldn't quote the rule being discussed in this thread- its simply not right. -Brando Last edited by Brandon Holley : 13-08-2014 at 11:49. |
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#5
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Re: Pneumatic Restrictions & Improvments
It seems strange to mince words. Air is air. It makes sense to limit what compressors are available in the onboard system, since this governs availability of air during a match. But if we are allowed to start with our tanks charged, what difference does it make where this air comes from, or how quickly we are able to charge before the match? As long as the compressor/system being used is safe and doesn't knock out venue utilities.
It is legal to charge up other stored energy systems however we like (R34 from 2014 - of course, presuming it's safe), for example winding up a spring mechanism with a motor powered by any battery, or even with work directly from a person. So why limit how we charge up the pneumatic stored energy system before a match? What difference does it make if Team A filled up in 2 minutes and Team B filled up in 1 if they are otherwise identical at the start of the match? Last edited by Aren Siekmeier : 13-08-2014 at 11:55. |
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#6
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Re: Pneumatic Restrictions & Improvments
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However, I agree with the sentiment that offboard compressors should not be limited in the rate they can fill. If it can be powered and controlled by the robot it should be legal off board. Why? Because filling in 2 minutes and filling in 1 minute are identical from the perspective of on field performance. |
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#7
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Re: Pneumatic Restrictions & Improvments
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Since you are not limited (2014 at least) in storage volume, the difference between an unregulated air source & legal source could be 15 -20 minutes in extreme cases. Personally I would prefer they limit on board storage volume, but that would be harder to inspect for. Last edited by FrankJ : 13-08-2014 at 13:20. Reason: fixed date |
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#8
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Re: Pneumatic Restrictions & Improvments
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a 44 cubic inch tank at 120 psi stores .7 KJ of energy if released adiabaticly, teams won't effectively ustilize all .7 kJ of this for various reasons (losses in the system before it even gets to cylinders, as well as not operating down to 0 psi). So let's call this .35 Kj. I'm going to be lazy and approximate the FRC battery in the average bot as supplying 100 Amps at 10 V for 2 minutes, this is 60KJ/min for 120 KJ total. If a team precharges 20 44 in^3 tanks... you'd have ~ 7 kJ of usable energy versus ~120 KJ. Numbers are admittedly fudged here for quick calculation, but the trend is valid. The amount of air you can store in terms of energy is not much compared to the battery, so in the name of an even playing field in terms of energy use across teams, it really isn't a big deal. Now, limiting storage for safety reasons is another argument.... |
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#9
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Re: Pneumatic Restrictions & Improvments
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#10
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Re: Pneumatic Restrictions & Improvments
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As for general limits on the volume of storage, I would hope we wouldn't see those return. Prior to 2011, those volume limitations made it very difficult to use pneumatics without having an on-board compressor. With the weight and battery issues caused by a compressor, teams often skipped pneumatics entirely, with the exception of their shifters. Once the limits were removed we saw a huge increase in the usage of pneumatics, coupled with many unique designs which were previous infeasible or very difficult (254's jaw in 2011, 2056's shooter in 2013). There's been a definite evolution in design as a result of these more relaxed rules, and I'd hate to see us take a step backwards in terms of the functionality of robots. |
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#11
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Re: Pneumatic Restrictions & Improvments
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When it comes to limiting the allowable tanks, I see this as limiting a teams ability to research alternative storage tanks. There are a number of suppliers out there as well as custom options that would be more then acceptable under the current rules. As always, size and weight are a trade off in design. FRC558 has been looking into alternative tanks in the offseason, one potential source is the automotive aftermarket, since air suspension is a popular modification in the car world. I wish that there was a direct supply for an old KOP air tank, I believe we only received them in 2011 (Shown on pg. 11). There is always the old KOP tanks from Clippard. |
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#12
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Re: Pneumatic Restrictions & Improvments
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#13
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Re: Pneumatic Restrictions & Improvments
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However, I don't want to see plastic tanks go away and I don't want to see anyone wounded by shrapnel. I guess we just need some clear guidance on safe mounting practices. |
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#14
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Re: Pneumatic Restrictions & Improvments
Hopefully, if there is a future rule listing specific tanks that can be used, there will be a listed path towards getting additional tanks approved, similar to the pre-3/18 version of R31 in 2014, which had the blue box:
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#15
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Re: Pneumatic Restrictions & Improvments
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At the events I've been to, it doesn't seem like a lack of trust, but inspectors are strict. This hold teams to a high standard, and inspectors are generally very consistent. Also, on the topic of shop compressors, my team has never encountered trouble with having a compressor in our pit. We use it almost exclusively for our rivet gun, and it stays hidden away inside of a cabinet when not in use. |
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