Finding a transfer function from time series data in simulink

How do you write a code to obtain a transfer function from a graph of time series data that is produced through a simulink model.

[Mathieu NOE]

hello

from time data you can obtain a FRF with matlab function tfestimate

[Mathieu NOE]

problem solved ?

Answer 1

[nick]

Hi Zara,

As Mathieu mentioned you can obtain a frequency response function with the "tfestimate" function, which assumes the noise is not correlated with either the system input or with the system output.

Furthermore, you can also use the "tfest" function that estimates a continuous-time transfer function system with np poles, using all the input and output signals. The estimation algorithm initializes the estimable parameters using the method specified by the "Initialize Method" estimation option. The initialized parameters are updated using a nonlinear least-squares search method, specified by the "SearchMethod" estimation option. The objective of the search method is to minimize the weighted prediction error norm.

You can also use System Identification app to estimate the transfer function using input and response of the system. You may refer to the following guide for a step-by-step approach to estimate transfer function using the app :

https://www.mathworks.com/help/ident/ug/how-to-estimate-transfer-function-models-in-the-system-identification-app.html

You may refer to the following documentation to learn more about "tfest" function :

https://www.mathworks.com/help/ident/ref/tfest.html

Hope this helps.