Quote:
Originally Posted by wildaburk3160
Alright, after another talk with a mentor, it's been clarified that we don't need such exact precision. Our problem was that the motor was overshooting by over 20 pulses at some points, then taking 5-10 seconds to readjust to a reasonable position. So, I will take some previous suggestions about tuning the PID so that we can get the motor returning to a more reasonable pulse count, perhaps +/- 5 pulses, without wildly missing the mark beforehand.
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This sounds like your system is under-damped. Either add a mechanical dampening as suggested above, or (better) tweak your "D" (derivative) value to digitally dampen the system.
Using the analogy of an automobile suspension
- P tells how strong your spring is. That is, how fast does the pushback grow as you get farther from the set point?
- D tells how dampening your shock absorbers are. A large magnitude for D will help the values settle quickly.
- I doesn't have a good auto analogy unless you're a low rider with adjustable lift built into the suspension. I helps correct systems that settle out somewhere other than the set point. I usually think of it as the "Kentucky Windage" term.