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#1
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Re: Legality of Jaguar closed-loop control modes
The way I see it, the intent of these rules is to keep robots safe. Based on the technology, the cRIO needs to control the Jags so that the Field Management System can stop the robots. That is the point of the FIRST specific Jaguar firmware. All modes are safe and controlled by the FMS.
I expect the GDC will state that all modes are legal. -Joe |
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#2
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Re: Legality of Jaguar closed-loop control modes
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#3
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Re: Legality of Jaguar closed-loop control modes
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The key word is command, not data. |
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#4
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Re: Legality of Jaguar closed-loop control modes
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#5
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Re: Legality of Jaguar closed-loop control modes
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A "bad" student could reprogram the Jaguars with entirely new firmware, but this would break several other rules. There would be no doubt that they were doing something illegal though, so I don't know why they bothered to mention it here. |
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#6
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Re: Legality of Jaguar closed-loop control modes
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Since this "trusted heartbeat" is completely protected from interference - intentional or unintentional - from team software, it's this handshake between the protected FRC software on the cRIO and the FRC-specific firmware on the Jags that provides the required safety, allowing the driver station (or FMS when connected) to disable the Jag motor output, effectively negating any motor output "commands" that come from the team software on the cRIO or the internal control loops on the Jag. That's why the Jags require the special firmware when using CAN in order to be competition-legal. Quote:
To quote, adding my own emphasis: "There is no rule that prohibits the Jaguars from reading the values from the encoders, however note that Rule R49 requires that the ROBOT must be controlled by the cRIO." Here's a very plausible paraphrase (which is hopefully NOT what the GDC intends): "There is no rule that prohibits the Jaguars from reading the values from the encoders, however the Jaguars are only permitted to provide the values to the cRIO and all control calculations must be performed on the cRIO." Seems like we all agree it'd be non-sensical for the GDC to intend this - but it's unclear enough that we had visions of robots being wrongly declared illegal based on different inspectors' opinions. ![]() |
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#7
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Re: Legality of Jaguar closed-loop control modes
ok so if we interpret this the strictest way possible ( where the jag cant independently make a decision about its output ) wouldn't the current/voltage protection( a jag will shut itself off if it over amps or the voltage gets under 6v) built in to the Jags break this rule?
I dont think that this interpretation is correct ( or will remain correct ). |
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#8
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Re: Legality of Jaguar closed-loop control modes
The GDC has spoken, no closed loop control from the jaguar.
http://forums.usfirst.org/showthread.php?t=16326 Quote:
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#9
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Re: Legality of Jaguar closed-loop control modes
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It greatly complicates the cabling and increases the complexity of closed-loop control.Can someone ask on the First forum (it won't let me post) if this means that speed, current and position modes of the Jaguar are prohibited? If so, then there's no reason to use CAN bus. We might as well stay with PWM and the Victors. Heavy sigh... Last edited by taichichuan : 20-01-2011 at 23:56. |
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#10
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Re: Legality of Jaguar closed-loop control modes
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The only rule restriction is that commands must come from the cRio. The cRio can read the position (or speed) from the jaguar. PID (or other closed loop control) can be calculated on the cRio. Then the calculated voltage can be sent to the jaguar. Quote:
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#11
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Re: Legality of Jaguar closed-loop control modes
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#12
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Re: Legality of Jaguar closed-loop control modes
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The position (or speed) values can be read through the CAN bus (after the correct settings are loaded into the jaguar, SpeedReference for example). The voltage to send to the jaguar can then be calculated on the cRio. This does not use any of the Jaguar closed-loop modes, and so it seems legal. |
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#13
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Re: Legality of Jaguar closed-loop control modes
ok so what about the attached limit switches on the JAGS. by default ( and I don't think there is a way of turning this off) in both the PWM and CAN mode you can attach 2 limit switched to the Jag to stop the motor at both its low and high points . . am I to understand that these ports are off limits as well?
I get the desire to minimize “unanticipated surprises”, but we have had these devices for 3 seasons, CAN for 2 ( I would like to know if any one used the closed loop modes last year),and a whole range of beta tests ( not to mention the inclusion of the closed loop modes in the custom FRC Labview and Jag firmware builds). it just seams a little weird |
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#14
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Re: Legality of Jaguar closed-loop control modes
I see no justification for this ruling within rule <R62>.
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<R58> may provide some justification for such a ruling Quote:
I'd have to imagine that the people that put all the time and effort in to support the closed loop modes in the three different languages have to be a bit frustrated right now. I see the blue box under <R62> as a giant vote of "no confidence" in the Jaguar firmware. If the GDC believed that the Jaguar firmware would shut off the Jaguar outputs when the robot was disabled, what harm is there in allowing teams to use the closed loop modes with a "use at your own risk" disclaimer? Teams that spent offseason time working with the CAN bus and closed loop modes are also likely to be a bit aggravated. This type of thing is exactly the kind of transparency that people are asking for from FIRST. I don't think you would have seen any uproar about this if FIRST had issued a technology roadmap detailing what they were planning on opening when at the time they changed control systems. Then teams could have allocated their offseason time in a more applicable manner, perhaps practicing custom dashboards knowing that a laptop with a larger screen could be used, or offboard camera processing, knowing that COTS computing devices were going to be legal. |
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#15
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Re: Legality of Jaguar closed-loop control modes
...
Last edited by EricVanWyk : 21-01-2011 at 16:18. |
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