system identification procedure

Hello, anyone knows? How to make implementation or realization system identification procedure in matlab .Using simulink model(electric device model such as transfer function and integrator).From this model I can get experimental data(input and output).

[K E]

In case it is helpful, there is a System Identification Toolbox for Matlab/Simulink that can be purchased.

Answer 1

[Rajiv Singh]

Have Simulink data available in MATLAB workspace as double vectors. In the GUI (ident) import time signals to load the data. Then you work from there. If you are estimating models in the command line, package the data into an iddata object:

 data = iddata(y,u,Ts); % y = output; u = input; Ts = sample time

Then try various estimation commands, e.g:

 model = tfest(data, 2); % second order transfer function

The logged data (y,u) must be equi-sampled. If not, interpolate them to a uniform time grid.

[Amir Hejazi]

what should we do if sample time was not constant?

[Rajiv Singh]

interpolate or log data from the Simulink model at constant time intervals. Most identification routines do not handle irregularly sampled data.