Pneumatic Restrictions & Improvments

[AdamHeard]

Originally Posted by evanperryg

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]

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]

Originally Posted by Jon Stratis

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.

[lynca]

Originally Posted by jwfoss

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

Originally Posted by jwfoss

For pressure sensor, check out this one from ebay, 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]

Originally Posted by Andrew Schreiber

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.

[Karthik]

Originally Posted by Jon Stratis

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, 2056's shooter in 2013). There's been a definite evolution in design as a result of these more relaxed rules, and I'd hate to see us take a step backwards in terms of the functionality of robots.

[jwfoss]

Originally Posted by Karthik

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, 2056's shooter in 2013). There's been a definite evolution in design as a result of these more relaxed rules, and I'd hate to see us take a step backwards in terms of the functionality of robots.

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, since air suspension is a popular modification in the car world. I wish that there was a direct supply for an old KOP air tank, I believe we only received them in 2011 (Shown on pg. 11). There is always the old KOP tanks from Clippard.

[AdamHeard]

Originally Posted by jwfoss

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, since air suspension is a popular modification in the car world. I wish that there was a direct supply for an old KOP air tank, I believe we only received them in 2011 (Shown on pg. 11). There is always the old KOP tanks from Clippard.

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]

Originally Posted by AdamHeard

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]

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.

[FrankJ]

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.

[qnetjoe]

Originally Posted by jwfoss

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]

Originally Posted by AdamHeard

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.

[FrankJ]

Originally Posted by qnetjoe

...

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.

[kmusa]

Originally Posted by qnetjoe

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