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Switching from Constant value to PID controller

Asked by Giuseppe on 8 Feb 2015
Latest activity Answered by thamer aladnan on 10 May 2017
Hello!
thanks for your time! i need your help to solve this problem:
i have a system that works with a constant flow rate when the current is zero and, when current is higher than zero, the inlet flow rate must be controlled by a PID controller.
Now i tried to use a Switch block: - the first input is the pid controller; - the second one is linked to current (the control variable) - the last one is the constant block.
the problem encountered are: - i can't automatically tune the PID block ("Pid Tuner could not find an initial stabilizing controller using plant "Plant")
and so the program does not work..
any other solution/ Approach?
thanks to everyone!

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4 Answers

Answer by Giuseppe on 9 Feb 2015

Nobody can solve this problem? :(

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Answer by Arkadiy Turevskiy on 11 Feb 2015

Can you attach the model? Had to troubleshoot otherwise. One thing that could be happening is that PID Tuner works by linearizing a Simulink model "around" the PID Controller. If your switch is set to select not the PID output, but the other switch input, then the plant PID Tuner will see won't make any sense. So you can try to temporarily remove the switch, wire the PID Controller output to plant input directly and tune then.

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Answer by mkmat
on 19 Nov 2015

Did you manage to solve this issue?

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Answer by thamer aladnan on 10 May 2017

matlab is a fake software it never happens to be right with me ever!!

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