Re: Putting the 'I' in 'PID'
- From: Rick Armstrong <bogus@xxxxxxxxx>
- Date: Mon, 20 Apr 2009 02:31:25 -0700
Hi Ben,
You've already gotten some good advice. I will fill in some holes I
saw in the other replies:
1. Buy Tim's book.
Already have it and am studying it.
Sure, you can just keep asking questions here and
get the answers one reply at a time, but it's faster to read the book.
Ah, but no teacher can predict what knowledge gaps a student will
have! I get the feeling from reading Tim's book that it's aimed at
someone who has at least a minimal clue already. For example, the
answer to my original question was one that is _not_ in the book, and
the answer is probably pretty obvious to someone who's implemented a
PID controller _once_. My experience is that I can stare at the
equations ad infinitum, but until I bang my knuckles on something, I
just won't know what I'm looking at.
2. Beware any temptation to "help" your controller by directly clamping
things that aren't doing "what you want". Usually the misbehavior you
are trying to fix is due to a larger design issue (such as instability)
and your attempts to solve it by brute force will only make things worse.
I learned this the hard way before I learned #1 above.
Hmm. You're making me think that "add a little deadband to work around
tilt sensor noise" is a _bad_ thing :0
Think about what happens if you hang a small weight from one corner of
your vehicle.
That's actually one of the tests I had planned once I've successfully
implemented the 'I' part.
Thanks,
Rick
.
- References:
- Putting the 'I' in 'PID'
- From: Rick Armstrong
- Re: Putting the 'I' in 'PID'
- From: Ben Jackson
- Putting the 'I' in 'PID'
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