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Simulink® Model Discretizer

This interactive demonstration discretizes the Actuator Model in an aircraft Simulink® model.

If you haven't already, open the Simulink aircraft model, slexAircraftExample.slx.open the Simulink aircraft model, slexAircraftExample.slx.

Open the Model DiscretizerModel Discretizer by selecting the Analysis -> Control Design -> Model Discretizer... menu from the aircraft model. This brings up the Model Discretizer GUI.

The Simulink model window and the Model Discretizer GUI are laid out in the screen for easy navigation.

  • The model tree is shown in the left panel of the Model Discretizer GUI.

  • Discretization parameters are set through % the right panel of the Model Discretizer GUI.

  • Discretization status is shown in the lower part of the right panel.

  • By default, only continuous blocks are shown in the Model Discretizer GUI.

  • In the Simulink model window, blocks in red color are continuous blocks.

You can browse through the continuous blocks one by one using the model tree view. Select the View->Next continuous blockView->Next continuous block menu in the Model Discretizer GUI. This causes the Actuator Model to be highlighted.

Before discretizing the Actuator Model block, set the discretization parameters: transform method, sample time, critical frequency. Critical frequency has to be specified if the transform method 'tustin with prewarping' is selected.

After setting the discretization parameters, select the Discretize->Discretize current blockDiscretize->Discretize current block menu in the Model Discretizer GUI. Or you can just click the s->z button icon in the tool bar. The discretized Actuator Model is highlighted in blue color in the model.

By default, the Actuator Model was replaced by a discrete block beneath a continuous block dialog, allowing you to continue entering the Actuator Model parameters in the s-domain. Double click the Actuator ModelDouble click the Actuator Model in the model window. Two new fields 'Sample time' and 'Method' were added to the block dialog window . These parameters are used to automatically convert the continuous parameters to equivalent discrete parameters.

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