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Unread 24-11-2011, 16:41
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AKA: Samuel Lijin
FRC #0694 (StuyPulse)
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Re: [DFTF] Jags v. Vics...

Quote:
Originally Posted by AdamHeard View Post
That is an inadequate solution. I don't really understand the point of this feature, one would assume the designers of the Jaguar are aware of what motors we use?
To be fair, bringing the Jaguars to voltage fault, from personal experience, is very difficult. Last season, we did mecanum for the first time; believing that the potential for better control Jaguars offered was worth the departure from Victors, we set up a test drive base with Jaguars on a serial-to-CAN interface.

We ran into a number of issues with Jaguars; one in particular led us to do a number of stress tests to see how easily voltage faults were induced. Although the testing was relatively casual and we recorded no quantitative data, the only way we could ever induce voltage faults was by rapidly shifting from full forwards to full backwards multiple times within a few seconds.

To elaborate on other problems we had, I have to say that the issues began the moment we took them out of the box; I believe 3 out of an initial order of 9 were defects (configuration could not be accessed, did not respond to signal control, etc). More died after we put them onto an actual drive base; the most notable example was one that released magical blue flame in the middle of a driving tryout.

Other issues we ran into include CAN issues that could not be properly debugged because of issues possibly related to the proprietary code (as we could not effectively isolate said issues).

One point that I'd like to raise, non-performance related, is the encoder I/O interface on the Jaguars. One of their selling points is that they can be configured to run their own individual PID loops with encoder input, but that feature is somewhat tedious to utililze. The encoder input is a 5-pin PWM setup, whereas the USDigital optical encoders have a 4-pin output (Jaguars can take an index signal that these encoders don't). Most teams would have to cut up the KoP 3-pin and 2-pin PWMs and solder them to the encoder wires, which I personally find to be a tedious implementation. The alternative, however, requires teams to own the tools and materials necessary to produce their own 5-pin PWMs.
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