Frequency-Domain Validation of Linearization

Validate Linearization in Frequency Domain using Linear Analysis Tool


In this example, you linearize a Simulink® model using the I/Os specified in the model. You then estimate the frequency response of the model using the same operating point (model initial condition). Finally, you compare the estimated response to the exact linearization result.

Linearize Simulink Model

  1. Open the model.

    sys = 'scdDCMotor';
  2. Open the Linear Analysis Tool for the model.


  3. Linearize the model at the default operating point and analysis I/Os, and generate a bode plot of the result.


Estimate Frequency Response of Model

  1. Create a sinestream input signal for computing an approximation of the model by frequency response estimation. In the Estimation tab, in the Input Signal drop-down list, select Sinestream.

  2. Initialize the input signal frequencies and parameters based on the linearized model.

    Click Initialize frequencies and parameters.

    The frequency display in the dialog box is populated with frequency points. The software chooses the frequencies and input signal parameters automatically based on the dynamics of linsys1.

  3. Set the amplitude of the input signal at all frequency points to 1. In the frequency display, select all the frequency points.

    Enter 1 in the Amplitude field, and click OK. The new input signal in_sine1 appears in the Linear Analysis Workspace.

  4. Estimate the frequency response and plot its frequency response on the existing Bode plot of the linearized system response. Click Bode Plot 1.

Examine estimation results.



For more information about frequency response estimation, see What Is a Frequency Response Model?.

Choosing Frequency-Domain Validation Input Signal


Input SignalUse WhenSee Also
SinestreamAll linearization inputs and outputs are on continuous signals.frest.Sinestream



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