MATLAB: How to estimate a continuous time transfer function for a specific structure using the System Identification Toolbox

Question

I am attempting to use System Identification to calculate the coefficients of a transfer function. However, I am trying to find the coefficients of a model whose structure that I specify, and that does not seem possible. What I would like to do is specify the structure:

 H(s)=(K*(s+z1))/((s+p1)*(s+p2))

and have System ID calculate the values of K, z1, p1, p2.

Answer 1

A specified structure of a transfer function can be estimated using PEM on IDGREY models. You can download the following example and place these files on the MATLAB Search path:

mymfile.m

est_demo.m

If you have System Identification Toolbox 6.0 (R13SP1+), you can download the following example which uses IDGREY and IDPROC models:

mymfile.m

est_demo_ident6.m

If you have System Identification Toolbox 4.0.5 (R11), you can download the following example, which indirectly creates an IDGREY model:

mymfiler11.m

est_demo_identr11.m