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wrong frequency response of systems with delay #824

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fedeinthemix opened this issue Mar 29, 2023 · 2 comments
Closed

wrong frequency response of systems with delay #824

fedeinthemix opened this issue Mar 29, 2023 · 2 comments

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@fedeinthemix
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The frequency response produced by bodeplot and freqresp for systems with delay is wrong. Here an example for a ZOH:

using ControlSystemsBase
using Plots
s = tf("s")
Ts = 0.1
bodeplot((1 - exp(-s*Ts))/s, hz=true)

The gain as s -> 0 should be 1.0, but it differs substantially. This happens for any value of Ts different from 1.0. Here the magnitude (blue) compared with the correct one red
image

@baggepinnen
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You have forgotten to divide by Ts
image

@fedeinthemix
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Me stupid! Thanks for the answer and sorry for the noise.

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