14-03-2012, 23:32
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systems engineer (retired)
no team
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Join Date: Nov 2009
Rookie Year: 1969
Location: US
Posts: 8,105
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Re: Flywheels and Shooter Wheels
Quote:
Originally Posted by pfreivald
Quote:
Originally Posted by Cal578 View Post
Several people have mentioned PID control. Are you using the Jaguar built-in PID feature, or are you implementing it yourself in the cRIO? Either way, what's your tuning method, and how long did it take? We only have the Thursday at regional competition to get it done.
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Our shooter was working rather well on practice day, before very weird electrical problems knocked it out for the rest of FLR. Our tuning method took about an hour, and was as follows (using encoders for feedback):
Start with all values at zero. Increase P until further increases result in a similar stall below the threshold value. (Too low will result in stall, FYI, so start with a value above that). Decrease P to the minimum value in that diminishing-returns range.
Start with a large I. You'll notice that it takes a long time to get up to speed, but it does get up to the target value and holds steady without overshooting. Decrease I until you get a ramp-up that satisfies your needs.
Spin it up, then feed in a ball and make sure that it ramps back up to speed without oscillating. (Ours didn't oscillate using this method).
Leave D at zero.
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You didn't mention if you were using cRIO or Jag PID. I suspect cRIO since you said to start with large I ?
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