Hello,
I would like to control a cart driven by a hydraulic cylinder using PID control.
In oder to do so, I needed to first model my system by measuring stimulus & response signals by a DAQ then take the measured data and use Matlab system identification tool to simulate a model then use Matlab PID tool to figure out the PID pramaeters , I have given the valve of the hydraulic system a sinus wave which is the stimulus and recorded the position of the cart as the response signal, i have repeated the process several times with different frequenices & ampltiudes for the sinus input wave, the problem is when I run the data throught Matlab system identication tool I get different systems with different eigenvalues.
My questions are:
1- Why does Matlab system identification tool give completely different systems although the measured data are from one and the same system ?
2- What is the best technique for system idenfication of my system ?
3- Is my general approach correct; to measure the stimulus & response signals via DAQ & LabVIEW then take the data to Matlab and use system identication tool to model the sytem then finaly tune the PID controller by Matlab PID tool ?
4- If you have any recommendation regarding my approach please let me know
Thank you
