How do I estimate a transfer function and a bode response from sample data ?

Hi everyone. I'm working with a DC motor where I apply a voltage (input) and get a current (output). Both vectors with a sampling time of 0.00001s.

I gave the imput with the blocked rotor so I can get only the electrical dinamic 1/ Ls + R

1) How can I get a transfer function from my input/output, but NOT USYING IDENT ? (cause I'm not having very good results with ident)

2) How can I get a bode diagram from my input/output?

Thanks!

[Arkadiy Turevskiy]

When you say you are "not having very good results with IDENT", what do you mean? Can you be more specific, i.e., describe what you have tried, what results you got, and why you are not satisfied with them.

Arkadiy

Answer 1

[Pedro Villena]

Use an Nonparametric System Identification Theory, like Ziegler-Nichols Method.

Ziegler-Nichols Method is a graphical technnic that is not included in Identification Toolbox. If you search about this technich, you'll find the step to identify a 2nd order system, then you could validate it in Matlab.

[Piero]

How do I do that in matlab ?