How to estimate the transfer function of a plant from its input output characteristics in labview?

[rodgersimon]

How to estimate the transfer function of a plant from its input output characteristics in labview (i.e I have step response of plant and I want the transfer function)?

[Valentin.B]

Hi,

You should take a look at the following forum:

How to estimate transfer function from real measurements data

There is also documentation on such issue in LabVIEW:

Modeling a System

Finally, there are examples which show how to use this function in LabVIEW (Help>>Find Examples ..)

Reagrds,

[rodgersimon]

Sir,

What I have is 5 different outputs for 5 different step inputs. Now I want the transfer function. So how to get a transfer function (approximte will do)? I cannot find similar example so please help me.

[Henrik_Volkers]

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@rodgersimon wrote:

Sir,

What I have is 5 different outputs for 5 different step inputs. Now I want the transfer function. So how to get a transfer function (approximte will do)? I cannot find similar example so please help me.

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So you get 5 (more or less different) transfer functions..... where is the problem?

[rodgersimon]

I have done in Matlab using system identification tools. There is provision to get only one transfer functon based on the input output data. I want to do the same in Labview. I am new to labview. Can you specify the steps that I need to perform to get what I intend to get.

[Henrik_Volkers]

Frequency Response Function (Mag-Phase) VI

Owning Palette: Waveform Measurements VIs

Requires: Full Development System

Computes the frequency response and the coherence based on the input signals. Results are returned as magnitude, phase, and coherence.

or if you have the System Identification Toolkit

SI Estimate FRF VI

Owning Palette: Frequency-Domain Model Estimation VIs

Requires: System Identification Toolkit

Estimates the frequency response function (FRF) of an unknown system. Use the FRF to estimate a transfer function (TF) model or a state-space (SS) model of the system.

Wire data to the stimulus signal and response signal inputs to determine the polymorphic instance to use or manually select the instance.

[Henrik_Volkers]

Frequency Response Function (Mag-Phase) VI

Owning Palette: Waveform Measurements VIs

Requires: Full Development System

Computes the frequency response and the coherence based on the input signals. Results are returned as magnitude, phase, and coherence.

ANd much more if you have the System Identification Toolkit