How to use a model generated from System Identification Toolbox in my work space?

Hello,

I generated transfer functions for 2 inputs and 1 output using System Identification Toolbox. Then I converted to my workspace: now I have 1x2 idtf file in my workspace. How can I use next this? Basically I want to handle to my model new inputs to generate outputs.

Answer 1

[Rajiv Singh]

The result of estimation is an object of IDTF class. It has properties containing numerical values of numerator and denominator. It has methods for performing simulation (sim, lsim) and analysis (step, bode, pzmap etc)

• Extract out numerical values of numerator and denominator polynomials using the "Numerator" and "Denominator" properties, as in B = obj.Numerator;
• Use LSIM method for time domain simulation as in

[y,t] =lsim(obj, input, time)

See idtf documentation reference page for information on supported properties and methods of idtf object.

[Shaoyang Qu]

Dear Rajiv,

I find the 'lsim' results can be very different from the model output in the system ID app. How can I set the focus to simulation? I'm using the 'transfer function model' method in the app.