pid autotuner
Dear all,
I am doing project "temperature control using PID controller" .when we go for relay auto tuning of PID controller,we have to Substitute a relay with amplitude d and from the desribing function we get the eqn Ku =4d/pa .
my doubt here how will i obtain d (ie.,relay amplitude)?
In order to analyse this , I first implented simple ON OFF(relay) temperature controller .From that I observed the oscillations getting are asymmetric around the setpoint .In order to get symmetric oscillations, i know that we have to select a suitable value for d ? Is there any theoretical method to find d? I really got stuck in this part . Considering the fact that i want to design completely automatic system , i want my miccrocontroller to find d rather than manually . So it would be very helpful if anybody give me a solution for this .
hopefully,
--varun