PID folks have their say

When I decided to run Greg Baker’s story on automated tuning capabilities (Is automated PID tuning dependable?) in our January issue, I figured there would be some controversy. Discussing tuning topics is like asking if Yoda is smarter than Mr. Spock. After the story was published and we began to receive comments, I was having an email discussion with Greg and he mentioned that it is tricky to compare tuning functions because you usually don’t know how the controller is applying the PID algorithm.

As an interesting coincidence, that specific topic came up in Vance VanDoren’s article in February (Sorting out PID controller differences), where he points out that there are several "standard" PID equations, and if you don’t know which of them your controller uses, your tuning efforts may not produce the results you expect.

If you can’t get enough of PID discussion, there’s another blog that may interest you. It’s written by one Finn Peacock and goes under the name PID Tuning Blueprint. I won’t personally guarantee what you see there, but it never hurts to have one more resource.

Personally, my vote goes to Mr. Spock. Comments welcome.