Bode diagram at different amplitudes?

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Hello,
my system is non-linear (basically a 2nd order lag with a saturation, modeled in simulink). I need to generate bode plots while the system is excited by sine waves of different amplitudes (so amp1 -> bode1, amp2 -> bode2). I want to compare this plot with real life data.
What would be the best way to generate these plots in Matlab/simulink? I am aware of the bode-Block in simulink, but I can't figure out a way to introduce the amplitude parameter.
Regards, grub

Accepted Answer

Arkadiy Turevskiy
Arkadiy Turevskiy on 21 May 2014
The best option in this case is probably frequency response estimation .
Here is the relevant doc section .

More Answers (1)

Yao Li
Yao Li on 21 May 2014
Option 1: export the input and output data to workspace and plot the bode diagram Option 2: Set the input/output port in simulink. Open Tools->Control Design->Linear Analysis. There is an option for plotting bode diagram
I think even a non-linear system can be analyzed in this toolbox.
Anyway, there are many other options. i.e. system identification toolbox
  1 Comment
grub
grub on 21 May 2014
Option 1: export the input and output data to workspace and plot the bode diagram
How do you do this? I can export time-domain data. But the bode function from the control systems toolbox only accepts a model as an argument. I would have to calculate magnitude and phase for the plot myself?
In Option 2 I don't have the ability to control the input amplitude. My system behaves differently when you excite it with sin(wt) or 5*sin(wt).

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