I would like to share with you the success story (see below) from a BESTune user. I was also surprised by this success story because I thought BESTune could only tune PID controllers with fixed sample time.
When the user told me that his process (I guess it is a rotating wheel with lots holes and the problem is to control the time that elapsed from one hole to another, this way the speed of the wheel is under control), I started to think about how to solve the problem and finally I developed a scheme which I believe can solve the PID control problem with varying sample time. But the user said BESTune could solve the problem before I wanted to ask him to try my new scheme for varying sample time control problem.
Still I believe the new scheme should be used to deal with varying sample time control problem.
Dan
----------------------
Dan,
This has been very interesting.
The varying sample time was not accounted for in my integrator. Your program indicated I needed no Kd. Your program came up with completely different Kp and Ki terms that settled 20 % faster and with no oscillations.
Would you consider offering a stripped down version that I could incorporate into our Visual Basic Controls. I would supply the sample data set, the
sampling rate, dead time, and tightness could be passed constants. Your program would calculate Kp and Ki and pass them back to me. I think the graph of the raw data then tuned results would be good. I would not want manual tune or testing. We would support our customers.
We only make 3-5 machines a year. Initially there would be more as existing users update, probably 10 to start with. These would need to be versions
that do not expire.
You can leave your name on the program with all copyright info. I would recommend an About box for those who have other uses for this type of program. The users of these machines are Automotive Manufactures and Paint manufactures in quality control labs.