How to add measured frequency response function to Simulink as a transfer function block?

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DFfd 2022-2-8

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回答： Benjamin Thompson 2022-2-10

I have a set of frequency response data gathered by modal analysis, which are stored in format (frequency, Re, Im) like the following. The frequency resolution is 0.5 Hz and measured field is up to 200 Hz. Can I put this measured Gxx list as a transfer function block in a simulink model?

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Answer 1

Benjamin Thompson 2022-2-8

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Yes, Simulink has transfer function blocks. You will need to select transfer function coefficients that match your response curves well enough. There are a few apps in the Control System Toolbox that may help with that process.

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DFfd 2022-2-9

I was looking for transfer function fitting functionalities in like Estimating Models Using Frequency-Domain Data and tfest. However, they all require iddata which contains input and output signals in time or frequency domain. I already have the response function processed by modal analysis measuring software and don't want to use raw I/O signals as input.

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Answer 2

Benjamin Thompson 2022-2-10

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See the System Identification Toolbox documentation article "Frequency-Response Models", maybe the spa function.

Also if you Google the topic "transfer function estimation from bode plot" you will find many resources including YouTube videos, as this is usualy a first year controls class topic. Transitions in the slope and level of the plots correpond to roots in the transfer function equation.