Off robot air compressor

[RyanN]

This rule isn't very good for us. Our cart has a built in compressor (The one included with the kit of parts from last year) and it has the pressure switch connected to a relay, not a spike, that is switched on and off with a 30 AMP switch connected to the same type of breaker panel with a 20 AMP Auto-reset breaker that was also included in the kit last year. We basically got all the parts from last year's kit of parts except for the relay that we got at our local Radio Shack. Basically, this system is just as safe as the RC controlled setup, so why must FIRST make us hook up a controller just to control a compressor. If they make certain guidelines such as "If a compressor is used off the robot to charge the pneumatics, it must be controlled by the included pressure switch and must be fused using a 20 AMP fuse with the correct gauge wire."

EDIT: I guess one good thing about the off board compressor is that we can use the old batteries, unless they change that as well...

[Al Skierkiewicz]

This is one of the most heated items of the robot build over the last few years. Many people have brought up safety and related issues and a variety of other topics of what might be and what could be and what might fail. So, as an inspector and someone who has used both high and low pressure air supply for a variety of different tasks here are some things to consider...
I have seen injuries caused by failures of tubing due to over pressure, I have seen pressure regulators fail as open circuit, dumping high side pressure directly into the system. I have seen hoses flailing through the air under pressure, one actually knocking over a production line. I have found pressure relief valves that fail to open and pressure vessels that fail for any of a number of reasons. I have, as inspector, seen teams who thought it was OK to plug the compressor directly to a battery and watch the pressure guage and yank the power when they thought it was the right time. I have come across at least one team who had a car battery in their compressor rig with a switch and nothing else (breakers or fuses and certainly no pressure control). I have seen teams bring the 1/2 horsepower compressor out of their garage (capable of powering air tools) with a 2-1/2 gallon tank, to fill their robot and used the exhaust valve to regulate the pressure applied to the system. I have seen teams who didn't know how to plumb in the pressure guage and so left it off, same for the pressure exhaust valve. I have seen teams who did not know how to terminate tubing or to know that it was securely seated in the fittings. All of this and I am not even mentioning the use of pistons in dangerous ways. In fairness, I have seen equally destructive practices on mechanical systems and electrical systems. That is why we inspect.
Nasa is an organization that "backs up the back up" as so many others where safety is concerned. In this case, the pressure switch and RC/spike combination is backed up by the pressure relief valve on the compressor which in turn is backed up by the inspection team performing a check that all works as normal. So with these experiences in mind I do not see the rules for compressor use on or off the robot as excessive.

[Richard Wallace]

Al, that last post covers the topic very well.

I only want to add, for the benefit of those who may not have met Al at an FRC event yet, that he is one of the most experienced and graciously professional volunteers associated with FIRST. The view that he expresses above is directly in line with the stated intention of FIRST, reinforced by increased support in recent seasons, to make safety the top priority.

Because of this am confident that the off-robot compressor rules (conservative as they may be) will be applied as written at all 2007 FRC events. All teams should plan and design their robots accordingly.

[dlavery]

Originally Posted by sanddrag

On the topic of the pressure switch, as an inspector, I saw numerous teams without one at the regional. They didn't even know what it was or how to program it. No one had an extra. What were we supposed to do? Render their pneumatic system un-usable because it is missing the switch? Or (per the manual) not allow them to place their robot on the field because it was missing a (trivial) required part? They payed big bucks to field a robot (just like everyone else), so, that they did, and there were no problems.

"Render their pneumatic system un-usable because it is missing the switch?" "...not allow them to place their robot on the field...?" Yes, that is exactly what you should have done.** Why? Because that is what the rules demand. As an inspector, you have agreed to enforce the rules as written and not make up your own. You may or may not agree with the rules. But the simple fact is that you are there to enforce the rules that are in place, and that every team expects to be enforced. If you cannot or will not do that, then you should not be an inspector.

What about the team that fully complied with all the rules (as the vast majority of teams do), and went to considerable lengths to make sure that our robot was in full compliance, and had to compete against the team that you let slide through? They paid the same big bucks to put a legal robot on the field, and they expect every one of their competitors to do the same. If the rules-skirting team beat the rules-following team, did they really win? The rules-following team would have every right to be furious about the fact that you let a robot in violation of the rules out on the field to compete, and potentially knock them out of the competition.

Every year we get lots of folks whining and complaining about FIRST's "soft enforcement" of the rules on and off the field. Yet we only have to look to ourselves to see how it happens. In the great majority of cases, we - the members of the FIRST community - are the referees, inspectors, judges, and volunteers that are there to enforce the rules. But we keep coming up with endless reasons why this rule isn't fair or that rule isn't practical, and give permission to ourselves or others to violate them. And the end of that process is a rule book that is meaningless, professional behavior is thrown out the window, and a "win at all costs" mentality takes over everything. In other words, it becomes pro wrestling.

If we expect the rules to have any meaning, and if we expect the teams to pay attention to the rules so that we can have a fair and even competition, then we have to be the first ones to recognize and abide by them. That is true in every aspect of the competition - whether we are acting as mentors, competitors, judges, inspectors, referees, mechanics, or just members of the audience.

-dave

** and when you are finished, you should go to every effort that you can to help them locate the missing part, and get it plumbed into their pneumatic system so they can pass a real inspection and legally get out on the field and compete in full compliance with the rules.

[Travis Hoffman]

Originally Posted by Al Skierkiewicz

This is one of the most heated items of the robot build over the last few years. Many people have brought up safety and related issues and a variety of other topics of what might be and what could be and what might fail. So, as an inspector and someone who has used both high and low pressure air supply for a variety of different tasks here are some things to consider...
I have seen injuries caused by failures of tubing due to over pressure, I have seen pressure regulators fail as open circuit, dumping high side pressure directly into the system. I have seen hoses flailing through the air under pressure, one actually knocking over a production line. I have found pressure relief valves that fail to open and pressure vessels that fail for any of a number of reasons. I have, as inspector, seen teams who thought it was OK to plug the compressor directly to a battery and watch the pressure guage and yank the power when they thought it was the right time. I have come across at least one team who had a car battery in their compressor rig with a switch and nothing else (breakers or fuses and certainly no pressure control). I have seen teams bring the 1/2 horsepower compressor out of their garage (capable of powering air tools) with a 2-1/2 gallon tank, to fill their robot and used the exhaust valve to regulate the pressure applied to the system. I have seen teams who didn't know how to plumb in the pressure guage and so left it off, same for the pressure exhaust valve. I have seen teams who did not know how to terminate tubing or to know that it was securely seated in the fittings. All of this and I am not even mentioning the use of pistons in dangerous ways. In fairness, I have seen equally destructive practices on mechanical systems and electrical systems. That is why we inspect.
Nasa is an organization that "backs up the back up" as so many others where safety is concerned. In this case, the pressure switch and RC/spike combination is backed up by the pressure relief valve on the compressor which in turn is backed up by the inspection team performing a check that all works as normal. So with these experiences in mind I do not see the rules for compressor use on or off the robot as excessive.

So, Al, I imagine it would be a bit awkward to connect and disconnect the compressor lead wires to and from the Spike Relay on the robot every time a team wants to charge up their system. If a team mounted a suitable 2-way quick disconnect connector (like the red Anderson connectors only not nearly as beefy) somewhere convenient near the periphery of the robot and ran red and black pigtail leads back from the connector to the Spike, would that be a legal setup? Just curious. 48 hasn't used pneumatics since 2003, and I haven't had the opportunity to observe how teams with offboard pumps legally charge up their systems.

If the quick connector were legal, along with the air line from the pump, which would plug into the manual dump valve mounted to the accumulator, you'd have one power and one air connection. Plug in, open the valve, turn the robot on, charge up to full pressure, close the valve, power down the robot, remove the pump, and you're done. Correct?

[dlavery]

Originally Posted by T. Hoffman

If the quick connector were legal, along with the air line from the pump, which would plug into the manual dump valve mounted to the accumulator, you'd have one power and one air connection. Plug in, open the valve, turn the robot on, charge up to full pressure, close the valve, power down the robot, remove the pump, and you're done. Correct?

Exactly. It is that easy to use, and it is that easy to implement and be completely within the rules.

-dave

[Al Skierkiewicz]

Originally Posted by T. Hoffman

So, Al, I imagine it would be a bit awkward to connect and disconnect the compressor lead wires to and from the Spike Relay on the robot every time a team wants to charge up their system. If a team mounted a suitable 2-way quick disconnect connector (like the red Anderson connectors only not nearly as beefy) somewhere convenient near the periphery of the robot and ran red and black pigtail leads back from the connector to the Spike, would that be a legal setup? Just curious. 48 hasn't used pneumatics since 2003, and I haven't had the opportunity to observe how teams with offboard pumps legally charge up their systems.

If the quick connector were legal, along with the air line from the pump, which would plug into the manual dump valve mounted to the accumulator, you'd have one power and one air connection. Plug in, open the valve, turn the robot on, charge up to full pressure, close the valve, power down the robot, remove the pump, and you're done. Correct?

T,
The Anderson people make connectors for #10 wire that are small and the shells snap together to form as many contacts as you want and come in a vareity of colors. They are also available through the usual sources, Terminal Supply and Powerex. We have used them for years to make our robot modular. As to the rest of your post, YES. Tether, connect pump electrical and hose, open the exhaust valve, power the robot, wait until the pump is shut off under RC control, close the exhaust valve, shut down the robot and disconnect the electrical and hose from the outboard compressor. Check the pressure guage to make sure you are at no more than 125 PSI and go win a match.

[Alan Anderson]

Originally Posted by T. Hoffman

If a team mounted a suitable 2-way quick disconnect connector (like the red Anderson connectors only not nearly as beefy) somewhere convenient near the periphery of the robot and ran red and black pigtail leads back from the connector to the Spike, would that be a legal setup?

That's exactly what the TechnoKats did for the 2006 'bot, right down to the color of wires and brand of connector.

We also had a 2005 OI with a spare tether cable mounted to the frame holding the off-board compressor, so we didn't need to connect the "real" OI in order to get the robot to power up and run the compressor. The compressor frame had a spot to carry a battery as well; the drive team would charge up the pneumatics using the "pit" battery and quickly swap in a fully-charged "competition" battery.