View Full Version : Pneumatic Restrictions & Improvments
In 2014 we saw a large upswing of people using pneumatic for their launching mechanism. This created quite a discussion on rules and legal restrictions for pneumatics.
If you are the GDC , How would you improve the pneumatics rules next year ?
For example.
Why are we limiting CV , tubing and port size ? (CD thread (http://www.chiefdelphi.com/forums/showthread.php?t=125411) )
Why do we limit low-pressure to 60 psi compared to 70 or 80 psi ?
Are there any devices that could improve the pneumatic experience for most teams ?
In 2014 we saw a large upswing of people using pneumatic for their launching mechanism. This created quite a discussion on rules and legal restrictions for pneumatics.
If you are the GDC , How would you improve the pneumatics rules next year ?
For example.
Why are we limiting CV , tubing and port size ? (CD thread (http://www.chiefdelphi.com/forums/showthread.php?t=125411) )
Why do we limit low-pressure to 60 psi compared to 70 or 80 psi ?
Are there any devices that could improve the pneumatic experience for most teams ?
First of all, pneumatics restrictions were lessened by a lot this year. The CV of the valve restriction was removed.
The reason the GDC limits CV is for safety. If we had unlimited CV, and someone were to put their head against a medium to large size pneumatic cylinder, and it is accidentally actuated, the person would die.
sanddrag
24-07-2014, 19:26
Quick exhaust valves. PLEASE
First of all, pneumatics restrictions were lessened by a lot this year. The CV of the valve restriction was removed.
The reason the GDC limits CV is for safety. If we had unlimited CV, and someone were to put their head against a medium to large size pneumatic cylinder, and it is accidentally actuated, the person would die.
Even with our current systems that could happen, 2in bore cylinder with 60PSI behind it is a lot of force. Also some spring punchers were just insane in amount of stored energy.
Basically the hose (1/4) and the 1/8 NPT rule limits the "power available".
Personally I want to be able to use a 3000PSI CF paintball tank/regulator so I never have to charge air at a competition but I don't think that's happening anytime soon. :rolleyes:
apples000
24-07-2014, 19:54
First of all, pneumatics restrictions were lessened by a lot this year. The CV of the valve restriction was removed.
The reason the GDC limits CV is for safety. If we had unlimited CV, and someone were to put their head against a medium to large size pneumatic cylinder, and it is accidentally actuated, the person would die.
Very true.
This year, we were playing around with a pneumatic launcher, and we wanted to try it with shop air. Strangely, no air was coming from the valve, and after closing all the other valves in the room (it shuts off the compressor if it detects a leak) so I went to go to the maintenance room to check on the big compressor. It turns out the room's dump valve had a faulty contact, and when I opened up the electrical panel, the valve opened, pressurizing the cylinder very, very quickly. The cylinder and its bracket went flying across the table, both fittings were torn/snapped off. It left a sizeable dent in the sheet steel counter, and chipped off part of our CNC's safety shield!
DampRobot
24-07-2014, 20:05
Let us charge with offboard air compressors, even if we have one onboard.
If it's made legal for everyone, it's no longer a competitive advantage, and there are ways to let it happen safely. I'd argue it's much safer to go into the match with a cool compressor than a hot one which can melt tubing or drag on battery voltage.
Let us charge with offboard air compressors, even if we have one onboard.
If it's made legal for everyone, it's no longer a competitive advantage, and there are ways to let it happen safely. I'd argue it's much safer to go into the match with a cool compressor than a hot one which can melt tubing or drag on battery voltage.
As a robot 2014 inspector, this can be legal. You just have to power it from the robot. With either an 2nd spike or just unplugging the off board temporary. I know 987 actually had two off board compressors they switch between to make sure they never over heated.
Now I understand you probably mean just plugged in a off board into a battery, or using a shop air compressor. But safety concerns I would guess, have first to ban them and we have no power over that. Again rules many change in 2015, but doubt they would change this one.
As a robot 2014 inspector, this can be legal. You just have to power it from the robot. With either an 2nd spike or just unplugging the off board temporary. I know 987 actually had two off board compressors they switch between to make sure they never over heated.
R79 is pretty clear stating that you cannot. "One and only one compressor."
R79
Compressed air on the ROBOT must be provided by one and only one compressor. Compressor specifications may not exceed nominal 12VDC, 1.05 cfm flow rate.
R79 is pretty clear stating that you cannot. "One and only one compressor."
We had this debate .... and I think it was on QA too, one and one compressor = one running at a time. So you can have two in the pits/around, but you can't use them both at the same time (aka to charge air faster).
We had a pneumatic catapult. I found a way to actuate a 2in bore, 10in stroke at the speed of a 3/4 in bore, 4in stroke. So, staying within the regulations, we had the strength of a 2in bore with the speed of a small, 3/4in bore. :yikes:
Jon Stratis
24-07-2014, 22:02
We had this debate .... and I think it was on QA too, one and one compressor = one running at a time. So you can have two in the pits/around, but you can't use them both at the same time (aka to charge air faster).
I just checked, it wasn't specifically asked on the Q&A this past year. Regardless, R79 is very clear - your robot can only have one source of compressed air. Filling it with an off board compressor then using a different on board compressor during the match is two sources. If you dump pressure before the match, your fine... And as an LRI, that's what I'll do if I see a team charging with an off board compressor while having one on board.
We didn't have an on board compressor on our robot. As stated in previous post, we had two off board compressors and only used ONE at any given time.
DampRobot
25-07-2014, 01:44
As a robot 2014 inspector, this can be legal. You just have to power it from the robot. With either an 2nd spike or just unplugging the off board temporary. I know 987 actually had two off board compressors they switch between to make sure they never over heated.
Now I understand you probably mean just plugged in a off board into a battery, or using a shop air compressor. But safety concerns I would guess, have first to ban them and we have no power over that. Again rules many change in 2015, but doubt they would change this one.
I've seen people on these forums and elsewhere explicitly say that you can only have one compressor charging the robot's tanks, which means no off board compressors if you have an onboard one. Not that you're incorrect, but there's definitely a lot of misinformation out there about this.
Yes, that's what I mean. Having to enable your robot with the DS just to charge the tanks is a huge PITA. As long as you can demonstrate that your off board control system will shut off automatically at 120 PSI, and had an emergency pressure relief valve, I don't see how it's a safety concern. In any case, it's exactly how the inspectors determine that the regular onboard pneumatic compressor is safe.
headlight
25-07-2014, 09:45
Quick exhaust valves. PLEASE
Quick exhaust valves can be approximated by using a 2 port solenoid valve at the cylinder and controlling it through software to provide an additional dump path. It would be way easier if we could just use quick exhaust fittings.
I would like to be able to use mufflers. Please. It is a small purely aesthetic change but high flow vent caps on the solenoid manifolds ensure that nothing gets inside. And a high flow muffler on the manual pressure release vent plug just helps keep sound down and makes sure there isn't a blast of air blowing stuff around whenever you dump pressure.
If would be nice if the pneumatic rules were just slightly more clarified and consistent. Things like ball valves, can they be used or not? or can they only be used as the main pressure dump?
There is also an entire world of pneumatic logic that hasn't been particularly capitalized on.
I would eliminate plastic storage tanks completely. I would consider requiring that storage tanks be mounted to avoid damage by contact with the field or other robots, but that would be a hard rule to word.
One issue with shop compressors is that almost all the venues are power limited. You don't have enough power in the pits to run 30-60 compressors at the same time. A side effect of limited the compressor capacity is the it limits the practical amount of stored air on the robot. Maybe limit the stored air volume & open up off robot compressor sizes?
Jon Stratis
25-07-2014, 10:16
I've seen people on these forums and elsewhere explicitly say that you can only have one compressor charging the robot's tanks, which means no off board compressors if you have an onboard one. Not that you're incorrect, but there's definitely a lot of misinformation out there about this.
Yes, that's what I mean. Having to enable your robot with the DS just to charge the tanks is a huge PITA. As long as you can demonstrate that your off board control system will shut off automatically at 120 PSI, and had an emergency pressure relief valve, I don't see how it's a safety concern. In any case, it's exactly how the inspectors determine that the regular onboard pneumatic compressor is safe.
The issue with home-spun pneumatic systems like you describe is that they require a certain amount of knowledge and experience for someone to determine if they're safe... and unfortunately many of our inspectors don't have that knowledge or experience. By requiring specific parts, that it's hooked up in a specific way, that it runs from the robot control system, and specific observable operational behaviors, we can ensure a system is safe without requiring inspectors to be experts. It's the combination of known components with known behaviors and the observable behavior of the system that tells us it was hooked up correctly. With a home-spun system we don't have known components with known behaviors controlling it, so our observations from a single run don't tell us enough to ensure it's safe.
I know a number of years ago my team was working on an off-season project and a couple of the mechanical members decided to "safely" power the compressor by running one of the power leads through the pressure switch and plugging it into a battery. It worked a couple of times before the pressure switch stopped working, as the switch wasn't designed to handle that much current. Given a similar situation, a team could demonstrate proper behavior, only to have that behavior go out the window a few charges later!
JohnFogarty
25-07-2014, 10:54
Don't you just love the English language and how it can be vague and very specific at the same time?
I don't understand the whole issue of using an off-board compressor to store air into the robot's system if the off board compressor can easily be connected to the robot's control system (temporarily in place of the on-board compressor) so the the robot can control the air input for a pre-match charge. This way the on-board compressor won't heat up because it isn't being used pre-match.
What I'm seeing a lot of people say is that people used multiple compressors at one time to charge a system. I can see this being a bit of an isssue, but not the situation I mentioned above, because in the senario I provided there is only one compressor/air source connected to the robot's system at any given moment.
I just checked, it wasn't specifically asked on the Q&A this past year. Regardless, R79 is very clear - your robot can only have one source of compressed air. Filling it with an off board compressor then using a different on board compressor during the match is two sources. If you dump pressure before the match, your fine... And as an LRI, that's what I'll do if I see a team charging with an off board compressor while having one on board.
My apologies for mis-understanding and not being clear.
What I meant was was switching between two off board compressors, to make sure none of the over heated but only using one actively at a time. While having no on board. My team had to do this due to the enormous (5gal) tank we had and we had deliberate over the "one and only one" rule.
But if a team were to have a on board and then disconnect it, and use an off board properly wired into the robot to pre-fill before a match so the on board stays cool during the match; I would think this is legal? Since air is only being provided by one compressor at a time that is wired legally.
But if a team were to have a on board and then disconnect it, and use an off board properly wired into the robot to pre-fill before a match so the on board stays cool during the match; I would think this is legal? Since air is only being provided by one compressor at a time that is wired legally.
This is legal, there was a clarification early this season, if I remember it correctly the requirement is that the compressor must be operated using robot control system.
Couple of years back I have seen teams using a off-board compressor directly plugged into battery and charging.. this is illegal.
The key thing is there are only so many safety inspectors who can check all on-board and off-board pneumatic systems. It isn't easy for these inspectors to twist and bend in every direction to access the on-board system. If teams are allowed for off-board control system (or worse no control system) and off-board compressor, now the inspectors will have to inspect these systems that may be on the cart or somewhere else. God bless them, they do a good job to keep everyone safe.
Mark McLeod
25-07-2014, 11:35
But if a team were to have a on board and then disconnect it, and use an off board properly wired into the robot to pre-fill before a match so the on board stays cool during the match; I would think this is legal? Since air is only being provided by one compressor at a time that is wired legally.
That would still be an obvious violation of R79.
If the compressed air is generated and mixed from more than a single compressor, then rule R79 is violated.
Jon Stratis
25-07-2014, 11:37
My apologies for mis-understanding and not being clear.
What I meant was was switching between two off board compressors, to make sure none of the over heated but only using one actively at a time. While having no on board. My team had to do this due to the enormous (5gal) tank we had and we had deliberate over the "one and only one" rule.
But if a team were to have a on board and then disconnect it, and use an off board properly wired into the robot to pre-fill before a match so the on board stays cool during the match; I would think this is legal? Since air is only being provided by one compressor at a time that is wired legally.
R79 did not include any wording indicating "at a time".
R79
Compressed air on the ROBOT must be provided by one and only one compressor. Compressor specifications may not exceed nominal 12VDC, 1.05 cfm flow rate.
The wording of the rule is straight forward and strict - all of the compressed air in use on the robot during a match must come from one and only one compressor. You can't mix sources between on-board and off-board, or charge halfway with one compressor and finish it off with another.
Personally, I think this rule could stand to be expanded a little to allow more variation in how pneumatic systems are charged, but as it's written it's very strict. Thinking about the reasoning behind it, I can see safety being one reason, fair play being another (not every team can afford to buy 2+ compressors just to charge their system), and good design being a third (If you can't charge your system without overheating your compressor, then you may want to re-think the design of the system and the constraints you have to work within, rather than just "throw more compressors at it" - not intended to be directed at you in particular, alternating compressors from one match to the other so they have time to cool down is certainly a valid engineering solution).
notmattlythgoe
25-07-2014, 12:16
There are ways of keeping a compressor from over heating. We had some over heating problems on our practice bot prior to going to our first competition, mainly because we had a lot of pneumatic components on our robot this year. What we did was place a fan on the robot blowing across the heat sink and the compressor never got hot to the touch after that.
nuclearnerd
25-07-2014, 13:24
Quick exhaust valves. PLEASE
Seconded.
Look, I get that there need to be restrictions on the pneumatic power available, but think about it this way: When the game requires your robot to through 4lb balls 10 feet in the air, you're going to need a certain amount of power. That power can be either delivered through a sketchy assembly of springs and a latch mechanism that was likely never meant to work under load
*or*
it can be delivered with commercial-off-the-shelf tubes, valves and cylinders that are engineered for the application, can be reliably assembled without machining resources, and have published specifications to govern their use.
Honestly, pneumatics are the safest way to deploy a given amount of power IMHO.
Seconded.
Look, I get that there need to be restrictions on the pneumatic power available, but think about it this way: When the game requires your robot to through 4lb balls 10 feet in the air, you're going to need a certain amount of power. That power can be either delivered through a sketchy assembly of springs and a latch mechanism that was likely never meant to work under load
*or*
it can be delivered with commercial-off-the-shelf tubes, valves and cylinders that are engineered for the application, can be reliably assembled without machining resources, and have published specifications to govern their use.
Honestly, pneumatics are the safest way to deploy a given amount of power IMHO.
It's worth noting that allowing quick exhaust valves doesn't really increase the amount of available power, since it's legal to simply leave one of the orifices on a two-stroke cylinder open to the atmosphere. I imagine the motivation for not allowing them is something else (thought I have no idea what that may be).
AdamHeard
25-07-2014, 16:11
It's worth noting that allowing quick exhaust valves doesn't really increase the amount of available power, since it's legal to simply leave one of the orifices on a two-stroke cylinder open to the atmosphere. I imagine the motivation for not allowing them is something else (thought I have no idea what that may be).
Was this unique to this year?
A 2011 Einstein team ran quick exhaust valves (968).
sanddrag
25-07-2014, 16:14
It's worth noting that allowing quick exhaust valves doesn't really increase the amount of available power, since it's legal to simply leave one of the orifices on a two-stroke cylinder open to the atmosphere. And this is why they should be legal. The only conceivable safety concern I can come up with relating to their use is you can move fast in two directions instead of just one with an open port Anyhow, to the OP, great thread.
Was this unique to this year?
A 2011 Einstein team ran quick exhaust valves (968).
I believe it was a Q/A:
https://frc-qa.usfirst.org/Question/34/is-a-quick-release-valve-such-as-the-one-sold-by-bimba-part-number-1bqev-considered-a-flow-control-valve-and-thus-a-legal-pneumatic-component-per-rule-77-f
And the tread this year concerning it: http://www.chiefdelphi.com/forums/showthread.php?t=124806
R79 did not include any wording indicating "at a time".
The wording of the rule is straight forward and strict - all of the compressed air in use on the robot during a match must come from one and only one compressor. You can't mix sources between on-board and off-board, or charge halfway with one compressor and finish it off with another.
Personally, I think this rule could stand to be expanded a little to allow more variation in how pneumatic systems are charged, but as it's written it's very strict. Thinking about the reasoning behind it, I can see safety being one reason, fair play being another (not every team can afford to buy 2+ compressors just to charge their system), and good design being a third (If you can't charge your system without overheating your compressor, then you may want to re-think the design of the system and the constraints you have to work within, rather than just "throw more compressors at it" - not intended to be directed at you in particular, alternating compressors from one match to the other so they have time to cool down is certainly a valid engineering solution).
And this is exactly what we did. There was simply two independently controlled compressors mounted on a small platform off board and in case there was a rapid turn around issue in eliminations (or a broken compressor) we were prepared to use the second one as a backup should the primary one be overheated. Per the reasoning demonstrated in some of these posts, anyone who has a broken compressor and replaces it would be breaking the r79 rule if they used the replacement to add air to the system. Head inspectors at two regionals agreed we were compliant. By the way, as I recall we never had to use the second compressor...and we eventually substituted for a Firestone heavy duty cycle ( also legal) compressor that worked fantastic at Champs.:)
DampRobot
25-07-2014, 21:55
I would eliminate plastic storage tanks completely. I would consider requiring that storage tanks be mounted to avoid damage by contact with the field or other robots, but that would be a hard rule to word.
Please, no!
Plastic tanks are one of my favorite technical developments for FRC in recent years. They make large volume pneumatic systems much, much lighter, and have raised the overall level of competition. There prevalence in FRC speaks volumes to how useful the average team has found them.
The failures in the white plastic tanks that have occurred have all been the result of user error, not defects in the tanks. All the failures that I have seen reported on CD were the result of overtightening the fittings on the white plastic tanks (and there have been no reported catastrophic failures of the black tanks). This problem has already been solved in two ways. First, the black plastic tanks (with integrated NPT fittings, which cannot be overtightened) are being sold, and can be exchanged for the white tanks for free. Second, there's been a great deal of education in the FRC community about the dangers of overtightening these fittings, both through Bills Blog, and these forums. Another possible way to resolve the issue would be through more rigorous pneumatic inspection, or even possibly a FRC-wide phaseout of the white plastic tanks (but NOT a blanket ban on plastic tanks in general).
We deal with a lot of stuff in FRC that's potentially dangerous. Dropped robots could break toes, batteries can leak, drills and saws can seriously injure students if misused, and any number of high potential energy mechanisms could inflict great injury if they failed catastrophically. Thankfully, our response as a sport isn't just to ban anything that could potentially be a safety risk. Instead, we maintain a safety-orientated culture, educate students and mentors about potential safety issues, and deal with potentially unsafe robot mechanisms on a case by case basis at regionals.
The right way to deal with this safety issue is through updated pneumatic inspections and through education to the community. Blanket bans are unnecessarily blunt, and would deprive teams of a great resource.
Please, no!
Plastic tanks are one of my favorite technical developments for FRC in recent years. They make large volume pneumatic systems much, much lighter, and have raised the overall level of competition. There prevalence in FRC speaks volumes to how useful the average team has found them.
The failures in the white plastic tanks that have occurred have all been the result of user error, not defects in the tanks. All the failures that I have seen reported on CD were the result of overtightening the fittings on the white plastic tanks (and there have been no reported catastrophic failures of the black tanks). This problem has already been solved in two ways. First, the black plastic tanks (with integrated NPT fittings, which cannot be overtightened) are being sold, and can be exchanged for the white tanks for free. Second, there's been a great deal of education in the FRC community about the dangers of overtightening these fittings, both through Bills Blog, and these forums. Another possible way to resolve the issue would be through more rigorous pneumatic inspection, or even possibly a FRC-wide phaseout of the white plastic tanks (but NOT a blanket ban on plastic tanks in general).
We deal with a lot of stuff in FRC that's potentially dangerous. Dropped robots could break toes, batteries can leak, drills and saws can seriously injure students if misused, and any number of high potential energy mechanisms could inflict great injury if they failed catastrophically. Thankfully, our response as a sport isn't just to ban anything that could potentially be a safety risk. Instead, we maintain a safety-orientated culture, educate students and mentors about potential safety issues, and deal with potentially unsafe robot mechanisms on a case by case basis at regionals.
The right way to deal with this safety issue is through updated pneumatic inspections and through education to the community. Blanket bans are unnecessarily blunt, and would deprive teams of a great resource.
Well if you are going for the massive amounts of air might as well get one of these: http://www.ebay.com/itm/5-Gallon-4-1-2-Port-Chrome-Silver-Air-Tank-Bag-Suspension-/251285996672?pt=Motors_Car_Truck_Parts_Accessories&hash=item3a81d00480&vxp=mtr
They are thin sheet metal, and weigh only about 4-5lbs if i can remember correctly and pressure rated for 200psi. To till them we got the 100% duty cycle compressor from vlair and also later upgraded to the Firestone compressor which is much beefier then the KOP vlair.
Please, no!
Plastic tanks are one of my favorite technical developments for FRC in recent years. They make large volume pneumatic systems much, much lighter, and have raised the overall level of competition. There prevalence in FRC speaks volumes to how useful the average team has found them.
The failures in the white plastic tanks that have occurred have all been the result of user error, not defects in the tanks. All the failures that I have seen reported on CD were the result of overtightening the fittings on the white plastic tanks (and there have been no reported catastrophic failures of the black tanks). This problem has already been solved in two ways. First, the black plastic tanks (with integrated NPT fittings, which cannot be overtightened) are being sold, and can be exchanged for the white tanks for free. Second, there's been a great deal of education in the FRC community about the dangers of overtightening these fittings, both through Bills Blog, and these forums. Another possible way to resolve the issue would be through more rigorous pneumatic inspection, or even possibly a FRC-wide phaseout of the white plastic tanks (but NOT a blanket ban on plastic tanks in general).
We deal with a lot of stuff in FRC that's potentially dangerous. Dropped robots could break toes, batteries can leak, drills and saws can seriously injure students if misused, and any number of high potential energy mechanisms could inflict great injury if they failed catastrophically. Thankfully, our response as a sport isn't just to ban anything that could potentially be a safety risk. Instead, we maintain a safety-orientated culture, educate students and mentors about potential safety issues, and deal with potentially unsafe robot mechanisms on a case by case basis at regionals.
The right way to deal with this safety issue is through updated pneumatic inspections and through education to the community. Blanket bans are unnecessarily blunt, and would deprive teams of a great resource.
There have been other causes for tank failures than over tightened fittings. Improper mounting, abrasions, impacts have been documented causes of failures.
The white Clippard tanks have been banned, that is why FIRST sent black Clippard tanks to later events for the free exchange for the white tanks.
AdamHeard
26-07-2014, 00:06
There have been other causes for tank failures than over tightened fittings. Improper mounting, abrasions, impacts have been documented causes of failures.
The white Clippard tanks have been banned, that is why FIRST sent black Clippard tanks to later events for the free exchange for the white tanks.
It's a bummer that many inspectors confuse them for the pneuaire tanks.
sanddrag
26-07-2014, 12:42
It's a bummer that many inspectors confuse them for the pneuaire tanks.Which led to my students being improperly told our PneuAire tanks were illegal because they were "the white ones", and my students proceeding to disassemble our pneumatics system prior to inspection....
From this experience, I taught my students that they must be experts of everything (which they were not at the time), and always question the validity of an inspector's claims if they do not agree with our standard practices.
It was a good learning experience.
Al Skierkiewicz
27-07-2014, 11:05
Andrew,
The Cv, port size and tubing size are limits placed on design because this is an engineering challenge as much as a robot competition. These limits are in the same group as the limits on size, weight, electrical power source, quantity of motors, etc. They are also in place for those teams that lack a pneumatics mentor to show them proper procedures and safety methods. For teams that have sufficient resources to own more than one of something, you need to always keep in mind that there are a fair number of teams that can't afford even the simplest of parts and tools let alone a second compressor.
As such, I would like to suggest to others reading this thread that items claimed as having been ruled legal at an event or covered by a Q&A response may in fact be not correctly stated. The post may not give all of the available information surrounding that particular event. (see Mark McLeod and Jon Stratis' posts that relates the true info.)
mk.32, two compressors are not legal in 2014 and actually never have been even before we allowed off board compressors. The "one and only one compressor" language is very specific.
We will consider other suggestions i.e. high flow exhaust valves.
Al
cbale2000
27-07-2014, 12:18
There have been other causes for tank failures than over tightened fittings. Improper mounting, abrasions, impacts have been documented causes of failures.
The white Clippard tanks have been banned, that is why FIRST sent black Clippard tanks to later events for the free exchange for the white tanks.
I don't recall FIRST ever banning them, just strongly recommending they be changed and offering replacements. Our team was offered replacements for our white tanks on our robot at all 3 of our competitions this season, but we declined since the new tanks cannot be capped off at one end like the white tanks can be (and the layout of our pneumatic system required the tanks to be capped off on one end due to their positioning on the robot). The inspectors never had any problem with this.
Did we all miss a memo somewhere?
That would still be an obvious violation of R79.
If the compressed air is generated and mixed from more than a single compressor, then rule R79 is violated.
Maybe it's just me, but if this is the case, it's one of the most arbitrary and pointless rules FIRST has ever made. There is an obvious advantage (and maybe even a safety issue) with having two compressors running simultaneously, but I see no unfair advantage whatsoever in allowing a team to use a separate compressor to pre-charge a robot prior to a match assuming it is the only compressor running and all the other rules for off-board compressors are followed. It just allows a team to go into a match with a cooler compressor, the same effect which could easily be accomplished by having a fan blowing across the compressor or sealing the system from leaks and charging it a few minutes earlier to allow for cool-down time.
Honestly I think people are lawyer-ing over this too much, its obvious what the intent of the rule is, regardless of how you argue the wording.
Now, granted, this entire issue would be a moot point if the stock compressor was rated for continuous duty like the older ones were, since they virtually never got hot and there would be no need to use a separate compressor to pre-charge the system. If anything it only hurts newer teams by giving them a less effective compressor then older teams can afford to buy.
RyanShoff
27-07-2014, 14:15
I wish we could find a way to safely use 3-position solenoids with a closed center. They allow a cylinder to be stopped in the middle of travel.
DampRobot
27-07-2014, 14:34
I don't recall FIRST ever banning them, just strongly recommending they be changed and offering replacements. Our team was offered replacements for our white tanks on our robot at all 3 of our competitions this season, but we declined since the new tanks cannot be capped off at one end like the white tanks can be (and the layout of our pneumatic system required the tanks to be capped off on one end due to their positioning on the robot). The inspectors never had any problem with this.
FYI, you can make and "end cap" on the black tanks by taking a short length of pneumatic tubing, folding it over on itself, ziptying it together, and sticking it in the NPT port of the tank. Worked well for us, and didn't leak in the slightest. Plus, it's super cheap.
AdamHeard
27-07-2014, 14:43
FYI, you can make and "end cap" on the black tanks by taking a short length of pneumatic tubing, folding it over on itself, ziptying it together, and sticking it in the NPT port of the tank. Worked well for us, and didn't leak in the slightest. Plus, it's super cheap.
They also sell plugs on mcmaster.
Andrew,
As such, I would like to suggest to others reading this thread that items claimed as having been ruled legal at an event or covered by a Q&A response may in fact be not correctly stated. The post may not give all of the available information surrounding that particular event. (see Mark McLeod and Jon Stratis' posts that relates the true info.)
mk.32, two compressors are not legal in 2014 and actually never have been even before we allowed off board compressors. The "one and only one compressor" language is very specific.
Al,
As you prepare for the 2015 season, I think you might want to revise the wording on this rule to make your intent clearer. Based on the comments in this thread alone, there seems to be significant confusion. Maybe it's because the ruling seems to be a bit counter-intuitive in comparison to what we're all used to.
The wording of the rule is straight forward and strict - all of the compressed air in use on the robot during a match must come from one and only one compressor. You can't mix sources between on-board and off-board, or charge halfway with one compressor and finish it off with another.
So a couple of questions for Al/Jon/Mark and any other LRI's on this rule based on what was written and enforced in 2014.
1. Is it legal for a team to alternate between multiple compressors during an event? i.e. Can a team charge with Compressor A after match 1, and then charge with Compressor B after match 7.
2. If #1 is legal, is it legal for a team to charge with Compressor A and then switch to Compressor B halfway during the charge.
Based on my reading of the rules and your posts in this thread, I'm thinking that both 1 & 2 are illegal. However, this runs contrary to how I've seen this rule enforced, and the interpretation of most people I've talked to.
3. If 1 & 2 are illegal, does this mean a team who blows their compressor during an event is now unable to use a compressor for the rest of the event?
This one seems a little silly, but based on "one and only one compressor" language, it makes me think that this team would now be out of luck.
If 1 & 2 are legal, I highly recommend that the wording be changed, so it's clear that teams are allowed to switch between compressors.
Anything we can do to make the pneumatics rules clearer for teams will go a long way in promoting their safe use throughout the competition.
Andrew,
The Cv, port size and tubing size are limits placed on design because this is an engineering challenge as much as a robot competition. These limits are in the same group as the limits on size, weight, electrical power source, quantity of motors, etc. They are also in place for those teams that lack a pneumatics mentor to show them proper procedures and safety methods. For teams that have sufficient resources to own more than one of something, you need to always keep in mind that there are a fair number of teams that can't afford even the simplest of parts and tools let alone a second compressor.
As such, I would like to suggest to others reading this thread that items claimed as having been ruled legal at an event or covered by a Q&A response may in fact be not correctly stated. The post may not give all of the available information surrounding that particular event. (see Mark McLeod and Jon Stratis' posts that relates the true info.)
mk.32, two compressors are not legal in 2014 and actually never have been even before we allowed off board compressors. The "one and only one compressor" language is very specific.
We will consider other suggestions i.e. high flow exhaust valves.
Al
"R79
Compressed air on the ROBOT must be provided by one and only one compressor"
So Al, are saying that no team can have a replacement/back up compressor (possession of 2)...that they must only have one in their pit? As I stated in my last post, we had no on board compressor, we used a legally configured off board set up. We did have a second compressor with same configuration of fittings and spike control available as back up. Air supplied to the robot system for a match was only provided by one compressor.
But out of curiosity, are you saying that anyone who replaced a faulty compressor (even in middle of filling up their system) would not have been in compliance with R79? I find it hard to believe the intent of R79 was to prohibit replacement of compressors and therefore needed filling of system air...of course, without addressing the issue in Q and A we are left guessing once again (which can still happen after an issue is addressed on Q and A anyways :))
First of all, pneumatics restrictions were lessened by a lot this year. The CV of the valve restriction was removed.
The reason the GDC limits CV is for safety. If we had unlimited CV, and someone were to put their head against a medium to large size pneumatic cylinder, and it is accidentally actuated, the person would die.
I don't think that's the only justification. Any linear puncher this year that accidentally actuated with a person's head near it would kill or maim them...with the failure mode being accidental release of a 1/2" or 3/4" bore piston.
There's any number of things that are legal and are just as dangerous...it has to be at least partially because of fairness or desire to limit pneumatics to a certain area.
A proposed tweak to the rule:
"All compressed air on the robot at any time must be provided by one and only one compressor [that meets the specs in the rules]."
What this tweak does is it allows the use of multiple compressors, but only one can be used to fill the robot and keep it filled. You can HAVE as many as you want on-hand, but if you fill the tanks with one, you have to drain the tanks before filling with another. And, they all have to meet the specs--no shop compressors can be used to fill the robot.
I wish we could find a way to safely use 3-position solenoids with a closed center. They allow a cylinder to be stopped in the middle of travel.
What's unsafe with how we would use them now? It shouldn't cause any sudden changes when you disable. You will likely need flow control valves to slow down the cylinder a bit so you can accurately stop it.
You can have a similar effect with two "FRC typical" latching double solenoid valves. On the first valve, you connect output A to the cylinder, and plug B's exhaust port. You do the same thing for the second valve.
When the first solenoid is at "A", and the second is at "B", the first solenoid pressurizes one side of the cylinder and the second vents.
When that arrangement is switched, (1st on B, 2nd on A), the cylinder goes the other way.
When both are at "A", you get the somewhere in the middle position.
When both are at "B", you get no pressure. Both of these states can be desirable.
The rule as it is now says "one and only one compressor". Karthik is right, "one and only one" means only one.(http://en.wikipedia.org/wiki/One_and_only_one). If you're not using the first compressor to ever put air in your robot, then you're in violation of the rule. There is a single unique compressor that is allowed to fill your robot.
There are a few things that I think are currently unsafe/have room for improvement with the pneumatics system.
1. Teams using valves that aren't double acting. When you go to emergency disable the robot, many things suddenly move. We had a few close calls with articulating wheels in 2012. You'd be walking around the robot when suddenly the laptop controlling it would go to sleep, and suddenly all the wheels would move up and the robot would fall to the ground.
Also, when a ref e-stops you, your single acting solenoids can change state, possibly launching a ball straight into a poor volunteer.
2. The pressure switch. We need a transducer that tells us the actual pressure and we need to be able to use that sensor to control the compressor. The large cycle range of the switch is not ideal for some teams. There are teams whose autonomous program just runs the compressor as soon as auto mode starts. Although the pressure never exceeds 120 psi, they can (and do) fail inspection.
There are teams out there who have their relief valve set below switch pressure. This way, the compressor is always running. A poor solution to a problem that doesn't need to exist.
Our auto mode left us with about 94 psi. It would be really nice to have the option to start the compressor to get us more pressure before our next shot.
This could also give us the ability to refill our tanks between matches without having to let out enough pressure to get the compressor to start.
3. Clarification on "reusing" air. Must we dump all air before we refill for our next match? We've been told yes and no. We've also had four back to back matches where there was not physically enough time to do a full refill.
4. Tiny stupid detail, but if R79 applies to ALL air, then you must use your robot's compressor to fill your pneumatic tires or balloons.
Jon Stratis
27-07-2014, 18:22
There was a relevant Q&A to the most recent rounds of questions...
Q209 Q. Rule R79: "compressed air on the ROBOT must be provided by one and only one compressor." 1) We can only use one compressor at a time, but can swap out compressors (e.g. if the one we are using starts to overheat). 2) We can only use one compressor for an entire event. Which reading is correct?
A. Situation 1, but also consider T8 and T10.
T8
At the time of Inspection, the ROBOT must be presented with all MECHANISMS (including all COMPONENTS of each MECHANISM), configurations, and decorations that will be used on the ROBOT during the entire competition event. It is acceptable, however, for a ROBOT to play MATCHES with a subset of the MECHANISMS that were present during Inspection. Only MECHANISMS that were present during the Inspection may be added, removed or reconfigured between MATCHES. If MECHANISMS are changed between MATCHES, the reconfigured ROBOT must still meet all Inspection criteria.
T10
If a ROBOT is modified after it has passed Inspection, other than modifications described in T8, that ROBOT must be re-Inspected.
My interpretation of this is that the GDC is saying that there is nothing inherently wrong with swapping out a compressor, but that doing so could be considered a modification and teams should check with an inspector when doing so. As Al can tell you, we've seen all sorts of things, and it's not uncommon for a team to leave a non-working part on the robot, even after the replacement is on (I've heard a story of a team having a half dozen burned out speed controllers on the robot... perfectly legal, but it's some awfully expensive ballast!). That's one reason why you should get reinspected... to make sure you didn't do anything accidentally that makes your robot illegal!
As Al indicated, there are numerous reasons we have these rules. R79 is really no different than R29 - one limits the number of compressors you can use with the robot, while R29 limits the number of motors. No one would argue that a team couldn't replace a burned out motor, and we shouldn't be trying to nit-pick R79 to death and say that we can't replace the compressor either.
The difference between the two is the way the items work - a motor creates mechanical energy from a supplied electrical source. Cut off the electricity, and the mechanical energy stops. A compressor, on the other hand, creates a reservoir of stored energy for later use - when you turn off a compressor, the energy is still stored for later use. The rules are simply controlling how energy flows within your machine - you can only use mechanical energy from a limited number of motors, and you can only use stored energy from a limited number of compressors (ie 1).
nuclearnerd
27-07-2014, 23:47
And this is why they should be legal. The only conceivable safety concern I can come up with relating to their use is you can move fast in two directions instead of just one with an open port Anyhow, to the OP, great thread.
Agreed. Without quick exhaust valves, you're forced to either halve the flowrate by running exhaust air back to the valve, or introduce some other mechanism to retract the cylinder - a complicated waste of weight.
I maintain that rules that discourage the use of pneumatics actually reduce safety. I would trust a factory-tested solenoid valve over a gerry-rigged latch holding back hundreds of pounds of spring force.
Thanks for finding relevant Q and A we used to guide our decision to have a back up system on hand Jon. Couldn't find it on Q and A forum... finally saw it on PDF :) And thanks for reminding others of the importance of flowing T8 and 10. Our back up system was mounted with primary compressor so both were inspected at same time. Still hate the vagaries of language when it comes to rules and interpretation and amazed at how many interpretations people can make from the same statement...
nicholsjj
28-07-2014, 03:45
I guess the only question I would have in regards to the on and off-board compressors is that is it really out of the realm of resources for most teams to accomplish in a safe manner that would give them any other advantage besides having a cooler on board compressor. Let's say that we could change the rules to teams using an on and off-board air compressor in their pneumatic system as long as both compressors are the exact same cost components and they follows all other pneumatic rules. All the teams would have to add to their system is andymark part am-2186 ($4) to where their current pressure switch is along with am-2257 ($3.50) in order to have a way of plumbing safely to their current system from an off-board compressor. The team could also have to wire their robot to have the ability to transfer their spike's power output from the on board compressor to the off board one as well. The last item a team would need would be the extra compressor, and let's assume that since the team doesn't have the extra resources to already go out and purchase something other than the now First Choice Viair then that will be the one they have to purchase at ($69). I will assume that the team will have extra pneumatic tubing available to plug into the close off valve. So to keep a system that doesn't burn a person's hand when they are transporting the robot on and off the field a team would need less money than what is needed for one double solenoid and the ability to mount a spike where it can power both compressors. Now is their anything I'm missing here that could become a more dangerous pneumatic that before or too much of a competitive advantage that a small team couldn't over come resource or knowledge wise. I just really don't like hot compressors and with short turn around times for teams I think allowing an extra off board compressor to help that situation would be beneficial in fixing that problem.
Note I really respect the decisions by very great people that go into making the rules and I just would like to see if this can get looked at a bit more.
Al Skierkiewicz
28-07-2014, 08:33
Karthik,
It is my understanding of the intent of this rule is that only one compressor be used for competition. If that fails, as in other components, it may be replaced. It is my understanding/opinion that rules are in place to avoid even the hint that one team can have even a small advantage over another.
Eric, that wording was considered as rule verbage in the past. Simplicity was the deciding factor in that decision.
As to the other ideas about valves and holding air, the ultimate result must be to release all stored energy at the end of a match to force the robot into it's minimum energy state for transport. I most heartily agree with designing your system so that it does not move when enabled or disabled. My arm was crushed during an inspection when the arm fell during the power on tests when I asked for the robot to be disabled.
As to the pressure transducer operating the compressor, I came across more than one robot this year that used that method only to find out that the software was programmed to increase pressure above the specified 120 psi during certain conditions. In one case the max pressure was 145 psi. It was caught by an observant ref who doubles as an inspector for some events.
While some of these items may seem like nitpicking, please put yourself in the position of being a team who was beat in a critical match and then finds that the team that beat them had that second compressor filling their tanks or that system pressure was above 120 psi. Oh yes, I just remembered my wife looking at a team in the queue with a battery and some alligator clips asking me "what are they doing over there?" Only to find that there were running the compressor from a robot battery to run the pressure up to maximum before they took the field. When I checked, the pressure appeared to be close to 150 psi before the team opened their dump valve. Of course we reinspected and re-calibrated the pressure relief valve for 125 psi and gave the team a stern warning.
Michael Hill
28-07-2014, 20:26
Karthik,
It is my understanding of the intent of this rule is that only one compressor be used for competition. If that fails, as in other components, it may be replaced. It is my understanding/opinion that rules are in place to avoid even the hint that one team can have even a small advantage over another.
I'm not sure why FIRST would try to choose to take any advantage a team has away from compressors. It seems somewhat inconsistent with many other things. For example, the Thomas 215 compressor is also a legal compressor, but costs A LOT more, but is definitely more capable than the standard Viair 90C. There will always be an advantage for teams with more money unless the rules explicitly specify every part, which is unreasonable. We already have a rule in place to limit advantages from more wealthy teams, the BoM cost limit. We don't limit the number of batteries or chargers teams can bring to the competitions, so why limit compressors?
cbale2000
28-07-2014, 21:38
I'm not sure why FIRST would try to choose to take any advantage a team has away from compressors. It seems somewhat inconsistent with many other things. For example, the Thomas 215 compressor is also a legal compressor, but costs A LOT more, but is definitely more capable than the standard Viair 90C. There will always be an advantage for teams with more money unless the rules explicitly specify every part, which is unreasonable. We already have a rule in place to limit advantages from more wealthy teams, the BoM cost limit. We don't limit the number of batteries or chargers teams can bring to the competitions, so why limit compressors?
Exactly, if the intent of the rule is to prevent two compressors being on the robot at once, then enforce that, but I can't think of any rational reason to prevent a team from using an external compressor to pre-charge a system with another compressor on the robot prior to a match so long as all other rules are followed and only one of the compressors is running at any given time. You're not preventing anything that couldn't be accomplished with a more expensive compressor.
Richard Wallace
28-07-2014, 21:53
... why limit compressors?Motor racing would be a different competition if its rules allowed unlimited fuel. Soccer would be a different sport if its rules allowed unlimited substitutions. Launching a competitive new product would be much less challenging if not for (usually unavoidable) limits on budget, schedule, and engineering resources.
Limits are part of the challenge. Without them, life would be boring.
The "one and only one" compressor rule puts a limit, based on rates of air flow and temperature rise, on the energy that can be used during a match by an FRC robot's pneumatic system. Matches might be made more interesting (or even more challenging) if that limit were raised -- but they would surely become less interesting if the limit were completely removed.
Michael Hill
28-07-2014, 22:00
Motor racing would be a different competition if its rules allowed unlimited fuel. Soccer would be a different sport if its rules allowed unlimited substitutions. Launching a competitive new product would be much less challenging if not for (usually unavoidable) limits on budget, schedule, and engineering resources.
Limits are part of the challenge. Without them, life would be boring.
The "one and only one" compressor rule puts a limit, based on rates of air flow and temperature rise, on the energy that can be used during a match by an FRC robot's pneumatic system. Matches might be made more interesting (or even more challenging) if that limit were raised -- but they would surely become less interesting if the limit were completely removed.
I don't know...I refuse to believe that this falls under the catch-all "but it's part of the challenge". I'm going to guess 80-90% of the teams are using the same Viair 90C compressor because that's what makes economical sense to them. There are some teams who have the money and are willing to spend it on any advantage they can get, and do with the Thomas compressor. Most teams are not willing to spend that much on a compressor, so that right there is an advantage to teams with more to spend.
I don't know...I refuse to believe that this falls under the catch-all "but it's part of the challenge". I'm going to guess 80-90% of the teams are using the same Viair 90C compressor because that's what makes economical sense to them. There are some teams who have the money and are willing to spend it on any advantage they can get, and do with the Thomas compressor. Most teams are not willing to spend that much on a compressor, so that right there is an advantage to teams with more to spend.
But due to the system restrictions (Cv, tube size, pressure, and any other constraints that are or have been applied), that more expensive compressor provides minimal advantage at the point of use--that is, at the cylinders. Sure, it might generate the air faster, and keep the stored pressure up more, and stay cooler, but once the air hits the regulator from 120 PSI to 60 PSI, all that advantage goes away at the working end of the system. I think that's why the compressor restrictions eased, and the air storage restrictions eased: Because those don't affect what happens at the working end of the system nearly as much as the other restrictions inherent in the rules. Guess what? If a team isn't a heavy air user, the Viair does make a lot of sense, both financially and from an engineering standpoint, because it doesn't need to do as much work as if the team is a heavy air user, constantly draining their tanks.
Now imagine if FIRST allowed larger-diameter tubing. I think we'd see a sudden run on the Thomas compressors, and suddenly every team that could afford them would be running them. Why? Because now you need more air faster. Lots more air, lots faster, and if the Viair compressors can't keep up, then it makes sense to use better compressors.
Michael Hill
28-07-2014, 22:35
But due to the system restrictions (Cv, tube size, pressure, and any other constraints that are or have been applied), that more expensive compressor provides minimal advantage at the point of use--that is, at the cylinders. Sure, it might generate the air faster, and keep the stored pressure up more, and stay cooler, but once the air hits the regulator from 120 PSI to 60 PSI, all that advantage goes away at the working end of the system. I think that's why the compressor restrictions eased, and the air storage restrictions eased: Because those don't affect what happens at the working end of the system nearly as much as the other restrictions inherent in the rules. Guess what? If a team isn't a heavy air user, the Viair does make a lot of sense, both financially and from an engineering standpoint, because it doesn't need to do as much work as if the team is a heavy air user, constantly draining their tanks.
Now imagine if FIRST allowed larger-diameter tubing. I think we'd see a sudden run on the Thomas compressors, and suddenly every team that could afford them would be running them. Why? Because now you need more air faster. Lots more air, lots faster, and if the Viair compressors can't keep up, then it makes sense to use better compressors.
Depending on how much air you use, the Thomas can let you drop an air tank meaning weight and volume savings. If FIRST were interested in limiting the advantage in this manner, why not put a similar limit on batteries and their chargers?
Depending on how much air you use, the Thomas can let you drop an air tank meaning weight and volume savings. If FIRST were interested in limiting the advantage in this manner, why not put a similar limit on batteries and their chargers?
Because it doesn't matter how many you bring (other than in terms of having spares ready to go for any team that needs them, especially your own), you can still only use one. And, the chargers are somewhat limited in practice, though not in quantity.
Yes, there are limits that seem rather arbitrary, and thus rather frustrating. Yes, that is a real-world challenge. (Along the lines of: No, you can't fit that there in the schedule. No, we don't have that kind of money lying around. No, you can't have any brown M&M's in the candy bowl. Yes, you have to be in bed by this time.) And it may be because those limits seem arbitrary that they're likely to stick around. Eventually, I predict that they'll either loosen up even further, or tighten up again on a couple of models. But until then, all the air on the robot has to come from one and only one compressor that meets robot specs. (And yes, that does exclude shop compressors.)
Al Skierkiewicz
29-07-2014, 07:43
Depending on how much air you use, the Thomas can let you drop an air tank meaning weight and volume savings. If FIRST were interested in limiting the advantage in this manner, why not put a similar limit on batteries and their chargers?
How are you calculating that? The volume specs are not that different that it would allow you to drop a tank. Please remember it is easy to make decisions based on your regional expectations for availability but we do have an international competition here and all parties have to be considered. While many teams are going to the Viair compressors for weight savings, they know the downside of using this compressor is the heat generated and the lower efficiency as the system approaches 120 psi. This is likely a good place to remind teams that at one time, the robot took the field with no pressure on board and had to fill the tanks once the robot was connected to the field. Prior to that, pneumatics were not allowed on FRC robots. There is a limit on batteries if you think about it. (12 volt SLA/AGM, 18 AH to be charged at no greater than the manufacturer's recommendation, which is 6 amps or less depending on the manufacturer.)
Michael Hill
29-07-2014, 08:35
How are you calculating that? The volume specs are not that different that it would allow you to drop a tank. Please remember it is easy to make decisions based on your regional expectations for availability but we do have an international competition here and all parties have to be considered. While many teams are going to the Viair compressors for weight savings, they know the downside of using this compressor is the heat generated and the lower efficiency as the system approaches 120 psi. This is likely a good place to remind teams that at one time, the robot took the field with no pressure on board and had to fill the tanks once the robot was connected to the field. Prior to that, pneumatics were not allowed on FRC robots. There is a limit on batteries if you think about it. (12 volt SLA/AGM, 18 AH to be charged at no greater than the manufacturer's recommendation, which is 6 amps or less depending on the manufacturer.)
The Thomas fills 13.7% faster than the Viair (1 CFM vs 0.88 CFM), meaning if you would have 8 tanks with the Viair, you can get by with 7 with the Thomas (And I've definitely seen more than 8 tanks on a robot as I'm sure you have in the past couple years).
The limit on batteries you mention is analogous to the CFM and PSI restriction on compressors. We aren't restricted on how many batteries or chargers we bring, but we're allowed to charge more than 1 battery at a time.
As far as I can tell, there have always been 4 basic categories when it comes to robot rules.
Rules regarding safety and damage prevention (i.e., max PSI, wheel treads, bumpers, wire size, etc.)
Rules regarding to the game (max size, weight, motors, etc.)
Rules regarding to interoperability with the field (requiring D-Link, CRio, etc.)
Rules regarding to simplification of inspections (Requiring only certain components being used like PDB, Circuit Breakers, Motor Controllers, etc.)
Under none of these categories would the compressor rule fit.
Jon Stratis
29-07-2014, 10:04
Rules regarding to simplification of inspections (Requiring only certain components being used like PDB, Circuit Breakers, Motor Controllers, etc.)
Those you list here are also safety concerns... Circuit breakers are present to protect the wiring from burning up, approved motor controllers are required so we can know the operating conditions of those controllers in situations like signal lose, and the required PDB to ensure all electricity is routed through proper circuit breakers. I strongly doubt you would want to supply your own PDB, have an inspector say "I've never seen that one before, I need you to take it off the robot and open up the housing so I can inspect it and ensure it's safe".
Believe me, if we didn't have those items required and provided in the KoP, you would see a LOT more robots going up in smoke on the field!
The Thomas fills 13.7% faster than the Viair (1 CFM vs 0.88 CFM), meaning if you would have 8 tanks with the Viair, you can get by with 7 with the Thomas (And I've definitely seen more than 8 tanks on a robot as I'm sure you have in the past couple years).
This is not true for operating robots.
Your quoted CFM specs are at 0 psi. The Thomas is not even rated to go to over 100 psi. Reading the specs at 80 psi, the Thomas will fill at .33 CFM, and the Viair will fill at .45 CFM. Above around 50 psi, the viair is faster.
The Viair is more efficient at higher pressures than the Thomas, but the thomas is better at filling empty tanks. The Thomas was never designed to go over 100 psi, so the efficiency drops off really quickly.
Team 358's test show that in the last 31 seconds of run time to fill tanks, the ViAir added 18 psi, but the Thomas added only 8 psi.
If you do some testing with the ViAir, you'll discover it's actually a pretty good compressor if it is kept cool.
Al Skierkiewicz
29-07-2014, 10:33
Michael,
You forgot to include engineering challenge rules which the battery, compressor, weight, size, motors and other limits etc. fit into.
Andrew Schreiber
29-07-2014, 10:55
We had this debate .... and I think it was on QA too, one and one compressor = one running at a time. So you can have two in the pits/around, but you can't use them both at the same time (aka to charge air faster).
Then this needs to be communicated to ALL LRIs. That rule was cited (in an incredibly rude manner) by the LRI at one of our events as the reason to remove a secondary compressor we used to power tools. He ignored any proof that we couldn't even connect the compressor to the robot (didn't have proper fittings) and was utterly unable to provide any clarification on the rule when asked. He also seemed to think that any spares we had needed to be outside the venue.
Al Skierkiewicz
29-07-2014, 11:21
Andrew,
Sorry for the demeanor of the LRI at your event. We often ask teams to remove shop compressors for several reasons. One being the possibility of filling robot tanks, one being the extreme current drawn during startup. At some events this enough to take four pits or more off line.
Andrew Schreiber
29-07-2014, 11:30
Andrew,
Sorry for the demeanor of the LRI at your event. We often ask teams to remove shop compressors for several reasons. One being the possibility of filling robot tanks, one being the extreme current drawn during startup. At some events this enough to take four pits or more off line.
Yes, another RI was kind enough to clarify that at the event.
For my own knowledge, in case this happens again, is there any recourse should a team feel that the LRI is being unreasonable? It was STRONGLY hinted by him that any further questions to him would be met with negative repercussions.
Tristan Lall
29-07-2014, 11:49
Although I acknowledge that FIRST can and probably should define constraints to level the playing field, it would be preferable that those constraints be defined in ways that make that intent obvious, while simultaneously being easy to understand and enforce.
That usually implies employing a straightforward restriction in place of a convoluted one. If FIRST really intends that the choice of compressor be used as a proxy for a limit on pneumatic performance (because the set of known legal compressors has a certain range of airflow, electrical and thermal characteristics), they should say so via an official channel. They should also endeavour to show that the restriction produces parity—with all the uncertainty in application of the rule, particularly off the field, this is hardly the case right know.
Or even better, if their objective is only to limit the on-field performance of the robot, rather than curtail off-field maintainability, they should write a specification that is permissive off the field, and restrictive on the field—like orifice size and pressure limits within the robot,1 rather than worrying where the air comes from.
Incidentally, apart from (arguably) being an arbitrary part of the challenge, is there a legitimate reason to limit the ability of a team to recharge from any safe air source (provided sufficient controls on pressure and flow are present on the robot)? FIRST should permit teams to recharge their pneumatic reservoirs from any regulated (e.g. to 120 lb/in2), gauged, room-temperature air or inert gas sources that are safe and legal to carry into and operate within the venue.
1 Cv is not an adequate way to specify this.
Al Skierkiewicz
29-07-2014, 11:54
Andrew,
The LRI should be reasonable and non-threatening. You can ask him/her to check with the FTA and Head Ref at your event for a clarification/consult. While I have asked teams to remove compressors at most events I attend, on occasion the team displays a distinct need for a particular tool that requires the air. Following a discussion with the team to refrain from using the compressor except when absolutely necessary, the event staff and LRI were able to come to an understanding. If the use tripped a breaker, of course all bets are off. There are always extenuating circumstances to any decision and that may have been the case at your event. An offender may have forced the issue and required all compressors to be removed before they would remove theirs. Yes, it happens. There are (rarely) mentors who are not willing to act with decorum or GP that make things unpleasant for all.
Al Skierkiewicz
29-07-2014, 11:58
Tristan,
While discussed, ad nauseum, in other fori let me copy it again here from paragraph 2 & 3 of Section 4, Robot Rules...
The rules listed below explicitly address what and how parts and materials may be used on a 2014 FRC
ROBOT. There are many reasons for the structure of the rules, including safety, reliability, parity, creation of
a reasonable design challenge, adherence to professional standards, impact on the competition, compatibility
with the Kit of Parts (the collection of items listed on any Kit of Parts Checklist, has been distributed via FIRST®
Choice, or obtained via a Product Donation Voucher (PDV), KOP), etc. When reading these rules, please use
technical common sense (engineering thinking) rather than “lawyering” the interpretation and splitting hairs
over the precise wording in an attempt to find loopholes. Try to understand the reasoning behind a rule.
In addition, another intent of these rules is to have all energy sources and active actuation systems on the
ROBOT (e.g. batteries, compressors, motors, servos, cylinders, and their controllers) drawn from a
well-defined set of options. This is to ensure that all Teams have access to the same actuation resources,
and to ensure that the Inspectors are able to accurately assess the legality of a given part.
Tristan Lall
29-07-2014, 17:48
Tristan,
While discussed, ad nauseum, in other fori let me copy it again here from paragraph 2 & 3 of Section 4, Robot Rules...
The rules listed below explicitly address what and how parts and materials may be used on a 2014 FRC
ROBOT. There are many reasons for the structure of the rules, including safety, reliability, parity, creation of
a reasonable design challenge, adherence to professional standards, impact on the competition, compatibility
with the Kit of Parts (the collection of items listed on any Kit of Parts Checklist, has been distributed via FIRST®
Choice, or obtained via a Product Donation Voucher (PDV), KOP), etc. When reading these rules, please use
technical common sense (engineering thinking) rather than “lawyering” the interpretation and splitting hairs
over the precise wording in an attempt to find loopholes. Try to understand the reasoning behind a rule.
In addition, another intent of these rules is to have all energy sources and active actuation systems on the
ROBOT (e.g. batteries, compressors, motors, servos, cylinders, and their controllers) drawn from a
well-defined set of options. This is to ensure that all Teams have access to the same actuation resources,
and to ensure that the Inspectors are able to accurately assess the legality of a given part.
That statement concerns the rules collectively, and I am of course aware of it. But absent clear evidence, it is illogical to believe that just because some rules are specifically intended to limit the energy sources and actuation options, that all rules are intended to limit those things, or that such intent is the primary motivation behind a particular rule.
To the greatest extent practicable, teams and officials should not be forced to speculate about the reasons for a particular constraint, as is clearly being done in this discussion. FIRST can easily make use of the blue boxes, or communicate through other channels, to alleviate that uncertainty.
Al Skierkiewicz
29-07-2014, 19:14
Tristan,
You posted...
... it would be preferable that those constraints be defined in ways that make that intent obvious, while simultaneously being easy to understand and enforce.
...If FIRST really intends that the choice of compressor be used as a proxy for a limit on pneumatic performance (because the set of known legal compressors has a certain range of airflow, electrical and thermal characteristics), they should say so via an official channel.
I merely showed you where First has done just that.
One....is the loneliest number that you'll ever do...Two....., can be as bad as one, it's the loneliest number since the number one...Aaaaaaa.
____________________
I cannot for the life of me understand how anyone can possibly misconstrue that particular rule as stated ".....One and ONLY ONE, Compressor may be used..." without some real out of bounds lawyering of the rule.
Of course spares (uninstalled of course), are allowed as "replacements" only....Not pre-installed in an onboard or off board compressor situation.
2 installed in an off board charging setup (pre-inspected or not), would be the exact same result, as 1 installed on board and 1 off board the robot would it not? As both still use 2 in the setup, whether actually plugged in or not at any time. (We have plenty of the older larger/heavier compressors sitting around....We cannot use them as belly pan mounted ballast though right...even if not plugged in and not plumbed, but properly and securely mounted? OF COURSE NOT, is the proper answer!)
And IMHO, both situations would violate the basic rule of only 1 compressor installed. (And the entire setup needs to be weighed as an integral part of the robot, and be completely powered by the robot and it's 1 also allowed battery, correct?)
If more than 1 installed and (possibly), working compressor (on board or off board is allowed), then 2 batteries installed on the robot would be OK also as long "as only 1 is plugged in or connected at a time." Do you see where this is leading?
Intentional "lawyerly" or not, violation of rules is usually referred to as "cheating" in most books, as it gives an unfair advantage to those that are following the rules.
_____________________
The above was directed at anyone arguing the easy as pie ONLY 1 Compressor Rule....Not any one party in particular. I am attempting to understand the argument as well as the next guy. Maybe I just misconstrued the meaning of "USING ONLY ONE COMPRESSOR." Or others have.
BTW, one of those big 12 Volt Muffin fans cool that compressor very well.
I cannot for the life of me understand how anyone can possibly misconstrue that particular rule as stated ".....One and ONLY ONE, Compressor may be used..." without some real out of bounds lawyering of the rule.
It is written in a way that means you must always use the same compressor to fill your robot. This is not practical, nor is it the intended meaning, as teams may need a spare.
Before you start attacking and calling people cheaters, I'd like you to show me a post where somebody argues that they can legally use two compressors at the same time.
Of course spares (uninstalled of course), are allowed as "replacements" only....Not pre-installed in an onboard or off board compressor situation.
Wrong. You'd better read up on what "one and only one" means. It means the same compressor must always be used. If that compressor breaks, you cannot fill your robot anymore. Obviously this makes no sense, so this is why we're having this discussion.
.We cannot use them as belly pan mounted ballast though right...even if not plugged in and not plumbed, but properly and securely mounted? OF COURSE NOT, is the proper answer!
Wrong again! The one and only one compressor refers to compressors providing compressed air.
Please read the manual.
orangemoore
12-08-2014, 17:36
It is written in a way that means you must always use the same compressor to fill your robot. This is not practical, nor is it the intended meaning, as teams may need a spare.
Before you start attacking and calling people cheaters, I'd like you to show me a post where somebody argues that they can legally use two compressors at the same time.
Wrong. You'd better read up on what "one and only one" means. It means the same compressor must always be used. If that compressor breaks, you cannot fill your robot anymore. Obviously this makes no sense, so this is why we're having this discussion.
Wrong again! The one and only one compressor refers to compressors providing compressed air.
Please read the manual.
You should reread rule 79
Compressed air on the ROBOT must be provided by one and only one compressor. Compressor specifications may not exceed nominal 12VDC, 1.05 cfm flow rate.
It doesn't restrict anyone from having more than one compressor just only one that compresses air for the robot.
And this was also clarified this year through the Q/A question #209
Q. Rule R79: "compressed air on the ROBOT must be provided by one and only one compressor." 1) We can only use one compressor at a time, but can swap out compressors (e.g. if the one we are using starts to overheat). 2) We can only use one compressor for an entire event. Which reading is correct?
2014-01-22 by FRC2485
A. Situation 1, but also consider T8 and T10.
Good job pointing out the importance of using/reading the Q and A each season, Roger! We always have one kid and one adult check almost daily/submit to Q and A as needed to ensure we are compliant throughout the build and competitions. Too painful to rebuild or change things at critical times as a result of not knowing what is or isn't legal...
Al Skierkiewicz
13-08-2014, 10:00
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.
evanperryg
13-08-2014, 11:02
Even with our current systems that could happen, 2in bore cylinder with 60PSI behind it is a lot of force. Also some spring punchers were just insane in amount of stored energy.
Basically the hose (1/4) and the 1/8 NPT rule limits the "power available".
Many mechanisms we've seen over the years could have been dangerous, but if a team is smart enough to design that mechanism, they're probably smart enough to handle it safely. I think that the pneumatics are so limited both out of safety, and so that their power doesn't far exceed the power of other FIRST components.
Let us charge with offboard air compressors, even if we have one onboard.
Why not just enable your robot for a little while in the pits and let the compressor run?
Why not just enable your robot for a little while in the pits and let the compressor run?
One main reason is the ability to get the accumulator tanks all the way up to the max allowable storage pressure. This will never be achieved using the control system as intended because the pressure sensor turns the compressor off at a lower then max pressure.
In all honest I see no reason why a team should not be allowed to pre-charge with a separate compressor as long as that separate compressor is within the limits of the rules.
I would think the original intent of the rule was so that teams would not use multiple compressors while on the field.
Everything is a trade off, and as huge fan of pneumatic use in FRC I have enjoyed the recent changes and look forward to more relaxed rules that still allow us to operate in a safe and creative manner.
notmattlythgoe
13-08-2014, 11:17
One main reason is the ability to get the accumulator tanks all the way up to the max allowable storage pressure. This will never be achieved using the control system as intended because the pressure sensor turns the compressor off at a lower then max pressure.
In all honest I see no reason why a team should not be allowed to pre-charge with a separate compressor as long as that separate compressor is within the limits of the rules.
I would think the original intent of the rule was so that teams would not use multiple compressors while on the field.
Everything is a trade off, and as huge fan of pneumatic use in FRC I have enjoyed the recent changes and look forward to more relaxed rules that still allow us to operate in a safe and creative manner.
The off board compressor must use the same system as an onboard compressor. So you'll never fill past the shutoff limit anyway.
Brandon Holley
13-08-2014, 11:20
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.
Hey Al-
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
Jon Stratis
13-08-2014, 11:24
One main reason is the ability to get the accumulator tanks all the way up to the max allowable storage pressure. This will never be achieved using the control system as intended because the pressure sensor turns the compressor off at a lower then max pressure.
This won't change through allowing the use of an off-board compressor to pre-charge the tanks while still having an on-board one. You would still need to use a pressure switch and have it controlled through the control system...
Jon Stratis
13-08-2014, 11:32
Hey Al-
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
Brandon - In general we don't like shop compressors in the pits at all, for a couple of reasons. First, the high-current they require at start up can often overwhelm the pit power supply. Doing so can trip breakers and shut down power to a group of pits, not just your own, in many venues (especially when running in high schools for district events). Second, when you have a shop compressor in a pit, there's no way for us, as inspectors, to know 100% that you aren't using it to charge your robot.
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.
Brandon Holley
13-08-2014, 11:42
Brandon - In general we don't like shop compressors in the pits at all, for a couple of reasons. First, the high-current they require at start up can often overwhelm the pit power supply. Doing so can trip breakers and shut down power to a group of pits, not just your own, in many venues (especially when running in high schools for district events). Second, when you have a shop compressor in a pit, there's no way for us, as inspectors, to know 100% that you aren't using it to charge your robot.
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.
Jon-
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
Aren Siekmeier
13-08-2014, 11:52
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?
Andrew Schreiber
13-08-2014, 12:03
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?
Presumably the reason to require the offboard compressors be controlled by the robot is to ensure that all safety systems are functioning anytime air is being loaded into the system. Otherwise I could over pressure my pneumatic system to 150psi and nothing would stop me. This is a dangerous situation.
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.
....Otherwise I could over pressure my pneumatic system to 150psi and nothing would stop me. This is a dangerous situation. ...
The on board relief valve will limit you to 125 psi or so. If the team is going to readjust that after inspection then they are willing to cheat in other ways as well? Typically one of the things the robot inspectors are looking at in queue is the storage & working pressures.
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.
What pneumatic tools do you use that can't easily be swapped out for a motor-driven equivalent?
Stuff we have already. We have pneumatic shears that are really awesome when cutting lots of lexan, but we don't want to spend $300 on new electric ones.
The main reason we bring a compressor is to use a nozzle and clear off chips and stuff like that.
Also, we use a pneumatic ratchet to allow us to get loosen/tighten bolts that are in tight spots. We've had some that we couldn't get with any other tool.
A few more-
pneumatic riveter, nail gun (wooden robots!), pneumatic cut-off tools (only $8 at harbor freight!). We use pneumatic drills sometimes to test mechanisms instead of a normal drill because they spin much quicker.
AdamHeard
13-08-2014, 12:44
The on board relief valve will limit you to 125 psi or so. If the team is going to readjust that after inspection then they are willing to cheat in other ways as well? Typically one of the things the robot inspectors are looking at in queue is the storage & working pressures.
Since you are not limited (204 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.
I was for limiting on board storage in the past, but when you compare the energy density of the tanks to the batteries, it's just not a big deal in my mind.
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....
Jon Stratis
13-08-2014, 12:45
Personally I would prefer they limit on board storage volume, but that would be harder to inspect for.
They did it in the past... For example, 2010 R72A:
One or two additional Clippard air storage tanks (Clippard Part Number AVT-32-16),equivalent to those provided in the kit. This means that up to four, and no more, Clippard air storage tanks can be used on the ROBOT.
I remember people rejoicing when this rule disappeared a few years back. To ensure safety from exploding tanks, though, it wouldn't surprise me if we saw something similar to this appear in the future... although it would probably just list legal storage tanks and not put a limit on them. Kind of like we have a list of legal batteries.
Jon Stratis
13-08-2014, 12:48
The main reason we bring a compressor is to use a nozzle and clear off chips and stuff like that.
Using compressed air to blow out metal chips and shavings is fairly dangerous, and if I saw it occurring I would personally get the lead safety adviser over there to talk with the team. When you blow those chips, they go everywhere, which could very easily include into the face and behind the safety glasses of someone on the other side of the robot or in the next pit over.
Edit: Check OSHA 29 CFR 1910.242(b). It requires that compressed air used for cleaning purposes must be reduced to less than 30 psig (pounds per square inch gauge, 204 kPa). Compressed air used for cleaning must only be permitted with effective chip guarding and personal protective equipment to protect the operator and other employees from the hazards of the release of compressed air and flying debris.
Using compressed air to blow out metal chips and shavings is fairly dangerous, and if I saw it occurring I would personally get the lead safety adviser over there to talk with the team. When you blow those chips, they go everywhere, which could very easily include into the face and behind the safety glasses of someone on the other side of the robot or in the next pit over.
We use a "safety" nozzle limited to 30 psi and we've always done it in some type of enclosure, like our pit's side area, which has walls over a trash can. If you end up doing serious machining at the event, it's really nice to have. We actually checked with pit safety people at the beginning of the event (as we often offer our pit resources to other teams), and they said they would be okay with it. Next competition, we'll be sure to check again, just to be safe.
I don't like limiting the storage volume. It doesn't make too much sense to me, as I don't think quantity of air is the big danger factor of FRC pneumatics.
I do agree that we should have a list of legal tanks, and I wouldn't be too upset if plastic tanks were banned.
Tom Bottiglieri
13-08-2014, 13:11
In general we don't like shop compressors ...
Who is we? Are you speaking for your regional? Are you being the voice of all inspectors? Is this just you?
Who is we? Are you speaking for your regional? Are you being the voice of all inspectors? Is this just you?
Not speaking for John... At Peachtree (Atlanta) the use of shop compressors where discouraged. I got the impression from the LRI that that was a source higher than him. As stated earlier power required for a shop compressors can be an issue.
We use a small shop vacuum for cleaning. You can also use it for blowing if the situation calls for it.
Jon Stratis
13-08-2014, 13:47
Who is we? Are you speaking for your regional? Are you being the voice of all inspectors? Is this just you?
This is something that has been discussed at every LRI training I've been to in NH.
AdamHeard
13-08-2014, 13:50
This is something that has been discussed at every LRI training I've been to in NH.
Second, when you have a shop compressor in a pit, there's no way for us, as inspectors, to know 100% that you aren't using it to charge your robot.
So you're saying it's official policy to not trust teams?
So you're saying it's official policy to not trust teams?
It is more of a guideline. :yikes: :)
Jon Stratis
13-08-2014, 14:00
So you're saying it's official policy to not trust teams?
Trust has to have limits at some point... otherwise why have inspections at all? For the most part, I trust that all teams do what they think is proper, appropriate, and legal. However, I also know that many teams don't read/understand the rules fully, and as a consequence they make mistakes and need someone to help them increase their understanding so they can compete on the same level as everyone else.
AdamHeard
13-08-2014, 14:07
Trust has to have limits at some point... otherwise why have inspections at all? For the most part, I trust that all teams do what they think is proper, appropriate, and legal. However, I also know that many teams don't read/understand the rules fully, and as a consequence they make mistakes and need someone to help them increase their understanding so they can compete on the same level as everyone else.
So presumably you'd talk to a team reminding them they can't go to a match with air from that compressor and call it good, or would you still ask they remove the compressor because you don't trust them to follow the rules?
Jon Stratis
13-08-2014, 14:18
For me personally, that's a non-issue... all the events in Minnesota do not meet the power requirements for a shop compressor in the pits, and we ask teams to remove it based on that alone.
Aren Siekmeier
13-08-2014, 14:26
For me personally, that's a non-issue... all the events in Minnesota do not meet the power requirements for a shop compressor in the pits, and we ask teams to remove it based on that alone.
Brandon - In general we don't like shop compressors in the pits at all, for a couple of reasons. First, the high-current they require at start up can often overwhelm the pit power supply. Doing so can trip breakers and shut down power to a group of pits, not just your own, in many venues (especially when running in high schools for district events). Second, when you have a shop compressor in a pit, there's no way for us, as inspectors, to know 100% that you aren't using it to charge your robot.
So can we agree that #2 is not a good reason?
Al Skierkiewicz
13-08-2014, 14:58
Many mechanisms we've seen over the years could have been dangerous, but if a team is smart enough to design that mechanism, they're probably smart enough to handle it safely.
If only that were true, ask any LRI.
Sorry to comment so late at the party, but there are few things that I would love to see change.
1.) Require soft start valves for pneumatics on a robot. This prevents rapid influx of air when connected to high pressure source. First can get them preset to a curtain fill rate and this only applies until the system reaches pressure. I personally can think of ten ways this would make events/robots safer but it is the one that I can't that are the most important.
2.)require Silencers/mufflers - for the love of robots please!
3.) relax the tubing size rules to allow for running larger manifolds. Feeding a 8 position manifold with the same size tubing as the outputs really limits the effectiveness of a lot of systems. A few times, we have used multiple regulators and smaller manifolds to skirt this rule. Plus with the way the current KOP is structured a team would have to have a reason to move off the more or less standard parts. This could easily be done by an ID area rule (for example if running 8 position manifold with 8 valves the max ID = sqrt(.161^2*number of valves).
4.) allow for different pressure sensors - please let me use a sunx :-)
5.) In the future, I would love to see the pneumatics module have a pressure transducer were you would plug an air line into; just to simplify things and provide a estimated pressure. That would just be nice.
Just an idea or two
FIRST trusts teams on many levels. Why should we have issues trusting teams to not use a shop air compressor to fill their robot? Compared to things like bag and tag, filling your robot with an air compressor is a pretty unimportant (and relatively safe, compared to other stupid things teams have done) thing to worry about. If you're going to disallow shop air compressors, you should only allow each team to bring one battery, as they could sneak in a second battery on their robot after inspection.
FIRST only works because we trust teams not to cheat in a high school engineering competition.
Shop air compressors should never be disallowed. There are very low power versions (less than 5 amps) that should meet power limits for most competitions.
There is one other potential reason for teams to want to use "shop air".
If you've got a properly sized compressor, you've got a very reliable and steady source of power for your tools, and possibly smaller tools to transport. If you use a cordless tool, you'll probably run out of charged batteries at some point, particularly if you've only got one or two batteries to start with. And if you've used corded tools, they're only good for as long as their cord, or you're using an extension cord, while an air line coils neatly but extends as long as you'd need it.
1.) Require soft start valves for pneumatics on a robot. This prevents rapid influx of air when connected to high pressure source. First can get them preset to a curtain fill rate and this only applies until the system reaches pressure. I personally can think of ten ways this would make events/robots safer but it is the one that I can't that are the most important.
One of the reasons many teams love pneumatics is the speed at which they actuate, I seriously hope this does not become a rule. We loved having the ability to use a valve with a higher Cv value this year specifically.
For pressure sensor, check out this one from ebay (http://www.ebay.com/itm/251362960044?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT), we used them on the robot this year to monitor both high and low pressure sides of the system.
snip
For pressure sensor, check out this one from ebay (http://www.ebay.com/itm/251362960044?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT), we used them on the robot this year to monitor both high and low pressure sides of the system.
+1 One the pressure sensor, We used it last year (Thanks CD for a previous post recommending it). It a was key factor in a QF buzzer shot for a win.
evanperryg
14-08-2014, 12:02
Personally I would prefer they limit on board storage volume, but that would be harder to inspect for.
It would be difficult to manage this rule, yes, but I think this would encourage better quality in pneumatic work. I won't name any specific teams/years, but I have seen a number of robots with a ridiculous number of tanks, that still struggle with having enough air in match.
In all honest I see no reason why a team should not be allowed to pre-charge with a separate compressor as long as that separate compressor is within the limits of the rules. I would think the original intent of the rule was so that teams would not use multiple compressors while on the field.
That makes sense. Perhaps rules could be changed to allow any teams to use external compressors, but specifically state that two compressors can't be used at the same time? My team always uses on-board compressors and we've never had any serious problems with having enough air in-match, but with some of the crazy things we saw teams doing with pneumatics this year, it would be cool to see more relaxed rules in the future.
So you're saying it's official policy to not trust teams?
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.
Andrew Schreiber
14-08-2014, 12:04
It would be difficult to manage this rule, yes, but I think this would encourage better quality in pneumatic work. I won't name any specific teams/years, but I have seen a number of robots with a ridiculous number of tanks, that still struggle with having enough air in match.
We were allowed one type of tank and up to 4 of them. It was really simple to check.
AdamHeard
14-08-2014, 12:17
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.
I've inspected since 2009 at many events. Never have I had a LRI even hint at distrusting teams in the above (or similar) situations. That's why I was concerned when a LRI literally stated (although it was slightly unclear) that at LRI training they were told to not trust teams to use shop compressors to not fill robots. Although now it seems like that's his personal view, and not what was conveyed at LRI training?
Either way, I've found more than half of my time inspecting is actually protecting teams from other inspectors with flawed interpretations of the rules. Too many inspectors (rarely LRIs luckily) have a seeming "Us versus them" mentality, rather than focusing on how to work with teams to get them the best experience they can.
Jon Stratis
14-08-2014, 12:31
Don't you just love when people on a forum take something you say, twist it around, and start beating you with it every chance they get? No where in anything I said did I say I didn't trust teams to do what they thought was best and legal. No where did I even imply that anything we look for at events is because we suspect teams of cheating, as opposed to acting out of ignorance (which is probably 99.9% of what we see as inspectors).
You'll note that I never said anything about not trusting teams - the word trust wasn't brought up by me. I simply pointed out that we don't know if teams are using a shop compressor to charge their robot, and that's one reason we don't like having them present in the venue. It's not a question of trust any more than any of the other rules we enforce at an event - it's a question of "what is that freshman who doesn't know the rules going to do when the pressure is on and he's sent to get the robot ready for the match?" Many, many teams use a shop compressor during the build season to power pneumatics for testing - I know my team does, and everyone on my team knows how to do so safely... and it's quite possible that one of my students, out of ignorance, would use a shop compressor to charge up the robot when in a time crunch/pressure situation.
AdamHeard
14-08-2014, 12:35
Don't you just love when people on a forum take something you say, twist it around, and start beating you with it every chance they get? No where in anything I said did I say I didn't trust teams to do what they thought was best and legal. No where did I even imply that anything we look for at events is because we suspect teams of cheating, as opposed to acting out of ignorance (which is probably 99.9% of what we see as inspectors).
You'll note that I never said anything about not trusting teams - the word trust wasn't brought up by me. I simply pointed out that we don't know if teams are using a shop compressor to charge their robot, and that's one reason we don't like having them present in the venue. It's not a question of trust any more than any of the other rules we enforce at an event - it's a question of "what is that freshman who doesn't know the rules going to do when the pressure is on and he's sent to get the robot ready for the match?" Many, many teams use a shop compressor during the build season to power pneumatics for testing - I know my team does, and everyone on my team knows how to do so safely... and it's quite possible that one of my students, out of ignorance, would use a shop compressor to charge up the robot when in a time crunch/pressure situation.
My apologies then, it really seemed like you were implying you didn't trust teams to do the right thing.
One of the reasons many teams love pneumatics is the speed at which they actuate, I seriously hope this does not become a rule. We loved having the ability to use a valve with a higher Cv value this year specifically.
Agree completely
For pressure sensor, check out this one from ebay (http://www.ebay.com/itm/251362960044?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT), we used them on the robot this year to monitor both high and low pressure sides of the system.
We used the same sensor as well with great success.
Maybe AndyMark or IFI can start stocking a pneumatic pressure transducer?
VEX robots also could use a pressure transducer !
Mark Sheridan
14-08-2014, 12:37
We were allowed one type of tank and up to 4 of them. It was really simple to check.
+1
The older rules were pretty good at keeping the playing field standardized.
I really like the increased volumes of air storage with the new rules but we could write the rules like the motor restrictions of the banebot motors or the bag/mincim. "Your allowed X amount of the following approved tanks"
So teams could max out volume with the larger ones, use smaller ones for better packaging or mix and match how they see fit.
Just a suggestion for a possible number for amount of tanks, i am thinking of 8. I think that might represent the upper limit for teams but for 987 that might be more like the median of their usual quantities.
I remember people rejoicing when this rule disappeared a few years back. To ensure safety from exploding tanks, though, it wouldn't surprise me if we saw something similar to this appear in the future... although it would probably just list legal storage tanks and not put a limit on them. Kind of like we have a list of legal batteries.
This seems like a good compromise. If FRC could do some testing and give us a list of certified safe air tanks, teams would have plenty of notice and an unambiguous set of guidelines to work with.
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 (http://www.team254.com/first/2011frc/), 2056's shooter in 2013 (http://www.2056.ca/year/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.
This seems like a good compromise. If FRC could do some testing and give us a list of certified safe air tanks, teams would have plenty of notice and an unambiguous set of guidelines to work with.
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 (http://www.team254.com/first/2011frc/), 2056's shooter in 2013 (http://www.2056.ca/year/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.
I couldn't agree more about with respect to the evolution of design that the current state of the rules has allowed.
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 (http://www.avsontheweb.com/product.php?productid=1406&cat=326&page=1), 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 (http://www.usfirst.org/uploadedFiles/Robotics_Programs/FRC/Game_and_Season__Info/2011_Assets/Kit_of_Parts/2011%20Kit%20of%20Parts%20Checklist%20Rev%20E.pdf) (Shown on pg. 11). There is always the old KOP tanks from Clippard (http://www.clippard.com/downloads/PDF_Documents/Clippard%20Full%20Line%20Catalog/Clippard%20Catalog%20by%20Page%20Number/001-095%20Air%20Cylinders/Page%20063.pdf).
AdamHeard
14-08-2014, 13:58
I couldn't agree more about with respect to the evolution of design that the current state of the rules has allowed.
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 (http://www.avsontheweb.com/product.php?productid=1406&cat=326&page=1), 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 (http://www.usfirst.org/uploadedFiles/Robotics_Programs/FRC/Game_and_Season__Info/2011_Assets/Kit_of_Parts/2011%20Kit%20of%20Parts%20Checklist%20Rev%20E.pdf) (Shown on pg. 11). There is always the old KOP tanks from Clippard (http://www.clippard.com/downloads/PDF_Documents/Clippard%20Full%20Line%20Catalog/Clippard%20Catalog%20by%20Page%20Number/001-095%20Air%20Cylinders/Page%20063.pdf).
A reasonable compromise might be something along the lines of plastic (or all tanks) shouldn't be capable of receiving direct impact from another robot. This is kind of a judgement call from the inspector, but it's really something teams should be doing anyway.
Andrew Schreiber
14-08-2014, 14:04
A reasonable compromise might be something along the lines of plastic (or all tanks) shouldn't be capable of receiving direct impact from another robot. This is kind of a judgement call from the inspector, but it's really something teams should be doing anyway.
I'm really hesitant to agree to anything that makes more judgement calls for anyone in FRC.
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.
Jon Stratis
14-08-2014, 14:39
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:
To seek approval for an equivalent battery, please contact frcparts@usfirst.org with the battery supplier and part number. Approved batteries will be added to the list above.
As for impact/mounting rules... While the GDC certainly could add them, IMO it's already covered under the safety rules - if a direct impact on something could result in shrapnel flying into the stands, then I would cite the safety rule in requiring a team to move it or shield it in some way. It's the same way inspectors reserved the right to ask teams to dry-fire a mechanism this year to ensure it was safe from spontaneous disassembly on the field, and how we've asked for various guards/protections on robots in past years.
I saw a large number robotics with plastic tanks mounted on the frame perimeter. Completely unguarded. We have dents in Al plate in similar places on our robot. The trouble with using the general safety rules is what is legal at one regional is not legal at another. It also requires the LRIs to use judgement with something they may not have much experience with. Much like shooter wheel guarding in 2013.
One of the reasons many teams love pneumatics is the speed at which they actuate, I seriously hope this does not become a rule. We loved having the ability to use a valve with a higher Cv value this year specifically.
I think you are confused what a soft start valve does, it only works only when the system is being initially charged. Once it reaches the open transition pressure the main valve opens that value does not close until the system reaches close transition pressure. I have an smc on my desk that has an open/close transition pressures of 3/.5 bar and is rated 10m^3/h; much higher than a FRC team would need/use. Plus it is only about 1.5x1.5x2.5" in size and weights a few ounces.
The sole job of the valve is to pressurize the system slowly to prevent the large initial pressure surge that can cause a cylinder rapid to the end of its travel.
On the field when teams uses external compressors that have a a few tanks attached, they turn the ball valve and you can see this jump clear as day. This usually happens during the down between a match and its replay. I personally saw this two or three times this year alone.
On the the pressure transducer the sunx is nice because you can configure the limits of the dio which makes it a programmable pressure switch combined with a digital gauge and a 0-10V analog for pressure feedback. All this can be done in the same package instead of three. This was really more about convinence than anything else.
Michael Hill
14-08-2014, 18:46
I've inspected since 2009 at many events. Never have I had a LRI even hint at distrusting teams in the above (or similar) situations. That's why I was concerned when a LRI literally stated (although it was slightly unclear) that at LRI training they were told to not trust teams to use shop compressors to not fill robots. Although now it seems like that's his personal view, and not what was conveyed at LRI training?
Either way, I've found more than half of my time inspecting is actually protecting teams from other inspectors with flawed interpretations of the rules. Too many inspectors (rarely LRIs luckily) have a seeming "Us versus them" mentality, rather than focusing on how to work with teams to get them the best experience they can.
When I've inspected at QCR, the LRIs basically said to not trust shop compressors. In 2013, we did in fact catch a team hiding a compressor to fill their (12?) tanks. At one point, our LRI told us inspectors to go around the pits looking for shop compressors and have the teams remove them.
...
On the field when teams uses external compressors that have a a few tanks attached, they turn the ball valve and you can see this jump clear as day. This usually happens during the down between a match and its replay. I personally saw this two or three times this year alone.
....
In 2014 at least, teams where not allowed off board storage tanks. Just the compressor. :]
Sorry to comment so late at the party, but there are few things that I would love to see change.
1.) Require soft start valves for pneumatics on a robot. This prevents rapid influx of air when connected to high pressure source. First can get them preset to a curtain fill rate and this only applies until the system reaches pressure. I personally can think of ten ways this would make events/robots safer but it is the one that I can't that are the most important.
I'm confused. Aren't you allowed to use a soft start valve already, since it's just another solenoid-operated valve?
Edit: Then again, since this should only apply to the case of an external compressor with external tanks, even a mechanical flow control would suffice.
-Karlis
Al Skierkiewicz
19-08-2014, 08:39
Everyone,
So you all understand the process here, LRIs are not distrustful. We do answer to the teams who ask, "why is that team filling their robot with a shop compressor?" If you have a shop compressor in the pit and are using it often and quite noticeably just prior to your match, it gets noticed by those around you, those passing your pit and especially by those competing against you or with you in the next match. Why? Because teams have used shop compressors to fill their robot in the past, have bypassed the pressure relief valve and ignored safety rules and design criteria. There is no official rule against compressors from FIRST but there are event rules that prevent such items particularly for their current draw and acoustic output. As we move to district events, power will become a specific issue. Larger regional events pay dearly for power distribution to be installed and to be maintained. I believe events like Boilermaker still bring in generators to supply power to the pits and field. When you use high current (that is start currents) devices, you risk taking the pits around you, the entire pit or the entire event down. I have volunteered at events that suffered from power outages for this exact reason. It may be easier to ask you to remove the compressor than to continue to field questions and complaints throughout the weekend.
As to current ratings on compressor, do not confuse "full load amps" with start current. Such a compressor rating at 10 amps will often have start currents in excess of 25 amps. If you are at the end of a power feeder, every drop upstream of your pit will experience significant brownout or breaker trips. If you read your instruction manual closely, you will see a caveat that you should have a delay trip breaker installed on the line you use for the compressor to prevent tripping a standard breaker or to use on a high current output if possible.
AdamHeard
19-08-2014, 12:56
Everyone,
So you all understand the process here, LRIs are not distrustful. We do answer to the teams who ask, "why is that team filling their robot with a shop compressor?" If you have a shop compressor in the pit and are using it often and quite noticeably just prior to your match, it gets noticed by those around you, those passing your pit and especially by those competing against you or with you in the next match. Why? Because teams have used shop compressors to fill their robot in the past, have bypassed the pressure relief valve and ignored safety rules and design criteria. There is no official rule against compressors from FIRST but there are event rules that prevent such items particularly for their current draw and acoustic output. As we move to district events, power will become a specific issue. Larger regional events pay dearly for power distribution to be installed and to be maintained. I believe events like Boilermaker still bring in generators to supply power to the pits and field. When you use high current (that is start currents) devices, you risk taking the pits around you, the entire pit or the entire event down. I have volunteered at events that suffered from power outages for this exact reason. It may be easier to ask you to remove the compressor than to continue to field questions and complaints throughout the weekend.
As to current ratings on compressor, do not confuse "full load amps" with start current. Such a compressor rating at 10 amps will often have start currents in excess of 25 amps. If you are at the end of a power feeder, every drop upstream of your pit will experience significant brownout or breaker trips. If you read your instruction manual closely, you will see a caveat that you should have a delay trip breaker installed on the line you use for the compressor to prevent tripping a standard breaker or to use on a high current output if possible.
What if that team is just filling because they are going to be testing in pit, or going to the practice field? The new Vair compressors are not robust, and limiting runtime on them is important to not enter a match preheated.
Jon Stratis
19-08-2014, 13:15
What if that team is just filling because they are going to be testing in pit, or going to the practice field? The new Vair compressors are not robust, and limiting runtime on them is important to not enter a match preheated.
It doesn't matter when it's done... using a shop compressor to fill the robot bypasses safety mechanisms. It would be very easy to over pressurize the system when using a shop compressor (an no, the blow off valve isn't a guarantee for this... I've seen teams that went through 2 regionals, Champs, States, and then show up at an off-season in the fall who swear they never changed it, yet have their valve set at 150+PSI. Unfortunately, not everything is caught by inspectors), and in fact we've seen teams do just that, intentionally. When in the privacy of your own shop, teams can set their own safety rules... when at an event, I personally would ask you to be respectful of the safety of everyone around you and only operate your robot as listed by FIRST, which means using a legal compressor set up to charge your pneumatics every time, even when not going to the field. I would also probably ask the Lead Safety Adviser to chime in on the issue as well - It would probably fall under their purview more than the LRI's, unless the compressor is used before sending the robot to the field.
AdamHeard
19-08-2014, 13:16
It doesn't matter when it's done... using a shop compressor to fill the robot bypasses safety mechanisms. It would be very easy to over pressurize the system when using a shop compressor (an no, the blow off valve isn't a guarantee for this... I've seen teams that went through 2 regionals, Champs, States, and then show up at an off-season in the fall who swear they never changed it, yet have their valve set at 150+PSI. Unfortunately, not everything is caught by inspectors), and in fact we've seen teams do just that, intentionally. When in the privacy of your own shop, teams can set their own safety rules... when at an event, I personally would ask you to be respectful of the safety of everyone around you and only operate your robot as listed by FIRST, which means using a legal compressor set up to charge your pneumatics every time, even when not going to the field. I would also probably ask the Lead Safety Adviser to chime in on the issue as well - It would probably fall under their purview more than the LRI's, unless the compressor is used before sending the robot to the field.
Then this brings up a whole can of worms that Tristan always likes to bring up. When and where do these rules apply? it currently isn't defined.
Also, what if the shop compressor isn't capable of reaching higher pressure than the robot? We have one that only hits 100 psi.
Al Skierkiewicz
19-08-2014, 13:50
Adam,
It doesn't really matter to the observer, all that is seen is a team connecting a robot to a shop compressor or the illusion that a shop compressor is being used with the robot.
Think about this...
A team sees a compressor in use in a team's pit, they inform the head ref when they take the field. The head ref assumes that the team used a compressor to fill the robot in spite of having been inspected. That team may get lucky and the ref calls the LRI for assistance (if they can be found before the start of the match), or the ref may simply release (recommended first response) all stored air, or the head ref can disable your robot for a perceived violation or in worse case, red flag or worse is issued. I don't want that, you don't want that and the team doesn't want that. Remember that the ref doesn't know that you only intended to use the compressor to operate a stapler or that you fill your tanks with it. They do not know if your relief valve is correctly calibrated and operating or that you legally filled your tanks. They simply see a robot with air and a complaint from another team. It would seem to me that removing the compressor so it is no longer an issue prevents all of these real or perceived issues from occurring.
AdamHeard
19-08-2014, 14:30
Adam,
It doesn't really matter to the observer, all that is seen is a team connecting a robot to a shop compressor or the illusion that a shop compressor is being used with the robot.
Think about this...
A team sees a compressor in use in a team's pit, they inform the head ref when they take the field. The head ref assumes that the team used a compressor to fill the robot in spite of having been inspected. That team may get lucky and the ref calls the LRI for assistance (if they can be found before the start of the match), or the ref may simply release (recommended first response) all stored air, or the head ref can disable your robot for a perceived violation or in worse case, red flag or worse is issued. I don't want that, you don't want that and the team doesn't want that. Remember that the ref doesn't know that you only intended to use the compressor to operate a stapler or that you fill your tanks with it. They do not know if your relief valve is correctly calibrated and operating or that you legally filled your tanks. They simply see a robot with air and a complaint from another team. It would seem to me that removing the compressor so it is no longer an issue prevents all of these real or perceived issues from occurring.
Wow. Another item on the list we have to be proactive about with people at events.
We currently have inspectors sign the form and note changes of our robot, and alliance partners robot's, ever since an unwarranted red card in 2013 cost us a regional. It's a bummer there is barely any space on the form for this.
The use of the air compressor is very nice, so we'll inform the LRI and Head Ref ahead of time that we understand the rules, and how we use the compressor.
It's crazy the burden is on teams to prevent unwarranted red cards... Guilty until proven innocent huh...?
Jon Stratis
19-08-2014, 14:50
It's crazy the burden is on teams to prevent unwarranted red cards... Guilty until proven innocent huh...?
What if you were on the other side of this? What if you saw a team filling their air tanks with a shop compressor, then watched them wheel it out to the field... when you complained to the head ref, you'd want him taking action, right?
It's not a question of assuming teams are intentionally trying to cheat or not... it's about trying to run an event that is both safe and fair to every team involved. It's not fair to team A to allow an illegal robot to compete against them, but it's also not fair to team B to red card them if they didn't really do anything... there's no way to ensure you're always making the right decision in every situation, as the information at hand may be the same. So you have to set up the rules and guidelines so you're consistent in the rulings, warn the teams ahead of time, and ask them to help you make the event a success for everyone.
AdamHeard
19-08-2014, 14:54
What if you were on the other side of this? What if you saw a team filling their air tanks with a shop compressor, then watched them wheel it out to the field... when you complained to the head ref, you'd want him taking action, right?
It's not a question of assuming teams are intentionally trying to cheat or not... it's about trying to run an event that is both safe and fair to every team involved. It's not fair to team A to allow an illegal robot to compete against them, but it's also not fair to team B to red card them if they didn't really do anything... there's no way to ensure you're always making the right decision in every situation, as the information at hand may be the same. So you have to set up the rules and guidelines so you're consistent in the rulings, warn the teams ahead of time, and ask them to help you make the event a success for everyone.
In complete honesty, speaking as a coach and inspector for many years, I'd be fine losing to a team that didn't get a redcard for illegaly precharging IF that meant the # of teams getting unwarranted redcards was reduced. I'd also always discuss with the team directly before going to a head ref.
"Let the kids play" is my philosophy. Rules like this aren't nearly as damaging to opponents if they are broken than someone running with illegal motors, or illegal batteries (which are far easier to catch).
Before someone takes my words the wrong way, we ALWAYS charge w/ the onboard, legal compressor for match play.
What I'm against is the culture of teams being expected to avoid certain things because people think it might be illegal and the head ref red cards w/o discussing with all parties involved.
The retroactive red card rules is one of the most terrifying in the book, and really doesn't give students a better experience at all.
Al Skierkiewicz
19-08-2014, 15:52
"Let the kids play" is my philosophy.
Agreed. The students want to win on a level field. If they lose they want to lose because a good team beat them, not a team that has an advantage, no matter how small or inconsequential. Inspections occur exclusively for this reason. Our (inspectors) responsibility is to level the field as much as is possible.
Travis Covington
19-08-2014, 17:58
Agreed. The students want to win on a level field. If they lose they want to lose because a good team beat them, not a team that has an advantage, no matter how small or inconsequential. Inspections occur exclusively for this reason. Our (inspectors) responsibility is to level the field as much as is possible.
This sounds wrong. I imagine if there was an exclusive reason to inspect robots it would be for safety.
This sounds wrong. I imagine if there was an exclusive reason to inspect robots it would be for safety.
I've got to agree. If a team wants to cheat in a competition for high school students and beat me, they could spend extra time working on their robot with almost no chance at getting caught. I'm not saying we should do everything based on the honor system (teams make honest mistakes sometimes), but having lots of these overkill rules leads to people making bad decisions, and lots of teams getting red cards.
I hate the atmosphere that we've had this year, where students and mentors honestly believe that inspectors and head refs are trying their hardest to give penalties and call teams out on subjective judgement calls, nonexistent rules, and where they "just can't remember what rule it is, but you broke it" as often as possible. This year, I've seen it all, from inspectors telling rookie teams (at the championship) misinformation, even after I walked up to the inspector, showed him the rule, and he agreed I was right.
With my experiences this year, it seems like inspectors/refs would much rather give out a bunch of red cards and prohibit things rather than to allow one or two robots on the field that may have charged their air tanks by shorting out the pressure switch for a few seconds or from a shop compressor.
I'll always do my best to make sure my team follows all the rules, but I wouldn't be too upset if my opponent fills his air tanks with a shop compressor. I'd be a lot less upset than if anybody got an incorrect red card/DQ.
Al Skierkiewicz
20-08-2014, 07:51
magnets you couldn't be more wrong. We do not want to prevent teams from competing and we certainly do not want to issue red cards. (The LRI in the past was the messenger on delivering red cards that were not related to game play. I hated that task.) We, as inspectors and refs, want to see everyone play as much as they want. My direction to inspectors is to try every trick to get a team on the field. That might mean disabling an illegal mechanism or not using pneumatics for a match. If the inspector is working with the team we will work out an agreement with the head ref and FTA to allow the team to participate while they are working. The head ref, FTA and LRI act as a group to insure that the competition is both fair and a good experience for all. The LRI oversees everything in the pit and on the robot, the ref everything on the field and with the game and the FTA is the FIRST rep at the event and is tasked with making everything (especially the field) run smooth.
One of the biggest issues we face as volunteers is the fact that it is hard to get experienced volunteers in key positions. As I look at the inspector list, for instance, there are only a handful of people that have been LRIs for more than a few years. I am a rare exception with more than 10 years of regional and Championship LRI experience. With the lack of experience comes some times when mistakes are made or rules are incorrectly interpreted. It is for this reason that all key volunteers have a series of other people to turn to. All LRIs have my cell phone number and refs can get to the Aidan. The FTA has all of those numbers and has people that can answer calls at HQ every weekend, up to and including Frank. In addition to that, we follow the Q&A and most LRIs will keep an up to date listing of the Q&A and team updates at each event they work. Finally teams question me here on CD or privately throughout the season. I respond to all of those inquiries or point the team to the Q&A. It is still surprising that more teams do not come to CD for answers or don't even know about the wealth of information that is here.
Travis, safety is a subset of this as part of the inspection process. We would never ignore a safety issue to get a team on the field.
magnets you couldn't be more wrong. We do not want to prevent teams from competing and we certainly do not want to issue red cards. (The LRI in the past was the messenger on delivering red cards that were not related to game play. I hated that task.) We, as inspectors and refs, want to see everyone play as much as they want. My direction to inspectors is to try every trick to get a team on the field. That might mean disabling an illegal mechanism or not using pneumatics for a match. If the inspector is working with the team we will work out an agreement with the head ref and FTA to allow the team to participate while they are working. The head ref, FTA and LRI act as a group to insure that the competition is both fair and a good experience for all. The LRI oversees everything in the pit and on the robot, the ref everything on the field and with the game and the FTA is the FIRST rep at the event and is tasked with making everything (especially the field) run smooth.
One of the biggest issues we face as volunteers is the fact that it is hard to get experienced volunteers in key positions. As I look at the inspector list, for instance, there are only a handful of people that have been LRIs for more than a few years. I am a rare exception with more than 10 years of regional and Championship LRI experience. With the lack of experience comes some times when mistakes are made or rules are incorrectly interpreted. It is for this reason that all key volunteers have a series of other people to turn to. All LRIs have my cell phone number and refs can get to the Aidan. The FTA has all of those numbers and has people that can answer calls at HQ every weekend, up to and including Frank. In addition to that, we follow the Q&A and most LRIs will keep an up to date listing of the Q&A and team updates at each event they work. Finally teams question me here on CD or privately throughout the season. I respond to all of those inquiries or point the team to the Q&A. It is still surprising that more teams do not come to CD for answers or don't even know about the wealth of information that is here.
Travis, safety is a subset of this as part of the inspection process. We would never ignore a safety issue to get a team on the field.
With all due respect Al, you are one LRI/Inspector out of many. I will say that I have encountered a number of inspectors this year going out of there way to fail robots during inspection (in one specific case, pressing down so hard on our bumpers that the noodles deformed well off the wood and failed inspection, our bumpers were properly constructed, fabric tight, and mounted at the correct height per the rules), as well as unjustifiable penalties at competition. While overall the general experience is good, a few bad eggs do leave a sour taste in my mouth, this year was less balanced then normal.
I truly feel that there are absolutely cases where there seems to personal "bad blood" between teams and volunteers.
In other news, this thread has gotten completely off topic. Pneumatics are one of my favorite things teach students about within robotics, and its a shame that the rules are not more well written and open. Perhaps its time to review this entire section of the manual as there are many artifacts from years past?
Al Skierkiewicz
20-08-2014, 08:06
jw,
I am the Chief Robot Inspector so the LRI should give me a call if there is a concern over a special rule or unusual robot design. As to the penalties this year, refs still have to follow the game manual just like I/we must follow the robot rules. Personally, I do not like games that include a lot of penalties. I also like games that allow good human players to affect the outcome of a match. This past game was one of the better games for that interaction.
I will back up Al with the statement that he is available during the season. As an LRI I have called him more than once during the season. I have been involved with FIRST since 2002 and have been on a team since then. Every year I find challenging questions by the different things that teams come up with. Many teams push the rules to the limit which is good as long as they don't go past.
If you ever volunteer at an event as an inspector that I am LRI you will get the same speech I use at every event that I do. " If you have any doubt about something, come and ask me. If something looks out of place or strange, ask me. ". I want all decisions to be by the rules. If I am not sure I will comb the rules, go to the FTA or contact Al. I will also send inspectors to help teams that seem to be in trouble. Al has beaten into me that our goal as inspectors and LRI's is to get every team into every match if at all possible. I spend a lot of time helping fix problems that are found during inspection. I don't want my inspectors to point to something and say "Fix!" then walk away.
Remember folks that we as volunteers give of our time because we believe in FIRST, and the students. Seeing teams succeed is the only reward that we need. Some of us have left our team to do what we do because we feel that our teams are in good hands and that we can contribute some of our experience to other teams.
Do I agree with all of the rules? Nope but they are still the rules. Do I agree with the set speed limits, nope but they are the law. We must learn to compete within whatever constraints (rules) that are put on us and rise to the challenge.
vBulletin® v3.6.4, Copyright ©2000-2017, Jelsoft Enterprises Ltd.