Quote:
Originally Posted by JVN
If my robot starts to smoke, I don't want a head ref anywhere near it.
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How nice of John to look out for the health and safety of our volunteers.
(I think he's really afraid someone is going to whip out the fire extinguisher and make sure the entire robot—not just the self-extinguishing speed controller—is good and dead.)
Quote:
Originally Posted by Richard
Could we find a way to have robots run compressors while we wait for them to synch with the FMS?
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Quote:
Originally Posted by Al Skierkiewicz
Get onto the field, turn your robot on, charge the tanks with either on board or off board compressor and step away.
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At SVR, I had a conversation about better practices for the pneumatic system, and one very reasonable thing that came up was the idea that it's not really important from a safety perspective that the cRIO control the compressor (via robot code). Granted,
the rules are the rules, so we have no such option for this year—but it would seem quite feasible to find a pressure switch with the appropriate current rating and triggering characteristics (e.g. not prone to oscillating on the margin of the pressure limit), and wire it inline with the compressor and power distribution block. (This could also be accomplished with a big, dumb relay and the existing switch.) For those teams that simply want their compressor to pressurize the tanks whenever they're low, this solution is simple and robust.
In fact, it's safer than the current implementation: there's no possibility of bad code causing the robot to ignore the pressure switch. It also renders the overpressure valve redundant to an even greater extent. (Which is great, because the overpressure valves are a hassle to set up properly, and they're often provided in the wrong configuration. Not to mention that they're not really rated for numerous cycles.)
With a relieving regulator on the low pressure side, actuators cannot overpressurize the high side. So the only way to overpressurize is via the compressor, which would be hardwired into a simple device designed to prevent that, rather than a feedback system with numerous other dependencies. It's those dependencies that give us the requirement that the off-robot compressor be controlled by the robot. Eliminate this dependency chain, and you solve the most insane part of the off-robot compressor problem—which, by the way, is as ridiculous as controlling a battery charger with the robot: sure you could, but why?
To top it all off, make sure to give teams the option to install feedback control, if they desire, by installing a pressure transducer in addition to the built-in pressure switch.
This would allow the tanks to charge whenever the robot is on. In some configurations, this could result in robot parts moving as soon as the switch is flipped, but that's not really any different from robots that use electromagnets (custom circuits). In fact, robots that leak air have the exact same theoretical problem: the lack of pressure could cause robot parts to move uncommanded...and I don't see leaky robots being banned. (Though maybe they should be....)
Note that the above presupposes that the compressor, even if off-robot, is powered by the robot (and therefore benefits from the hardwired pressure switch). I'd even be willing to entertain non-robot-based sources of air, provided that that there was an appropriate overpressure valve installed on the robot, and that the delivery device contained a gauge (and a regulator or other relief valve, as necessary) demonstrating to any observer that it was delivering no more than the maximum allowed pressure to the robot. And of course, whatever this device was, it would need to satisfy venue rules—so don't bring in a floor-mounted shop compressor.
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Quote:
Originally Posted by wilsonmw04
the question really is: When does the robot become the ROBOT? Most teams that pre-charge their robot take the position the the ROBOT begins when the starting buzzer sounds. The GDC is rather quiet on this point.
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That's a longstanding annoyance of mine as well. Obviously you can't enforce the entire rulebook based on the state of a robot undergoing maintenance. As best I can reckon, the rules are unambiguously intended to apply during an inspection, and during gameplay. (If it's a full inspection, then all of the robot rules should apply; if a partial one, then only the relevant ones. If it's a game, everything applies.) This means, as a practical matter, that some rulings have to be made as the robot is placed into the starting configuration before a match: it's not illegal until you try to play with it. Until that time, teams have plausible deniability with regard to configuration issues.
Although I hesitate to frame it in these terms, getting "inspected" (i.e. a partial inspection regarding one violation in particular) right before a match is probably preferable to the inspector reporting the same violation to the referee during or following the match. If before, you've got a moment to fix the problem—in this case, simply dump the offending air. (In theory, there does exist the possibility that the team can't fix a problem, and therefore the robot could be prohibited from taking the field.
2) By contrast, if the issue is reported during or immediately after the match, the sanctions from the gameplay section could be imposed (starting with a <G30> penalty, and taking it from there).
I also note that as a practical matter, inspectors will exercise discretion as to what violations would merit either of the above responses, as opposed to those violations which are minor enough to address after the match.
Quote:
Originally Posted by EricH
Unfortunately, FRC does not have a rule like this gem from the SAE Aero Design rulebook: "The violations of the intent of a rule will be considered a violation of the rule itself."
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I don't like the sound of that. They might as well have phrased it, "read our minds, because we're too lazy to think about the consequences of what we've written"....
1 Speaking of venue rules, since compressed gas cylinders are prohibited (to teams), that neatly rules out scuba tanks and the hassles involved with evaluating 3 000 lb/in2 regulators. I sometimes wonder if that's the hazard that FIRST was trying to avoid, when it banned all non-compressor sources of air.
2 It's my considered opinion that the 3-way red card for showing up for a match having an uninspected robot (<T03>) should only apply to a robot that did not ever pass inspection at the current event. The rules aren't clear about it, but that's a fair reading that gives the benefit of the doubt to teams, while maintaining what I would guess to be the primary intention of the rule. So, in my unofficial opinion, if you ever did find yourself in a situation where an inspector deemed the robot illegal right before a match, at least you could participate without completely ruining things for your alliance. (Best to have a pre-match conversation with the head referee and that inspector, if this ever comes up.)