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Unread 25-07-2014, 10:16
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Re: Pneumatic Restrictions & Improvments

Quote:
Originally Posted by DampRobot View Post
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!
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