Customizing Plots Inside the SISO Design Tool

Overview of Customizing SISO Design Tool Plots

Customizing plots inside the SISO Design Tool is similar to how you customize any response plot. The following property editors are specific to the SISO Design Tool:

  • Root Locus Property Editor

  • Open-Loop Bode Property Editor

  • Open-Loop Nichols Property Editor

  • Prefilter Bode Property Editor

You can use each of these property editors to create the customized plots within the SISO Design tool.

Root Locus Property Editor

There are three ways to open the Property Editor for root locus plots:

  • Double-click in the root locus away from the curve

  • Select Properties from the right-click menu

  • Select Root Locus and then Properties from Edit in the menu bar

This figure shows the Property Editor: Root Locus window.

Labels Pane

You can use the Label pane to specify plot titles and axis labels. To specify a new label, type the string in the appropriate field. The root locus plot automatically updates.

Limits Pane

The SISO Design Tool specifies default values for the real and imaginary axes ranges to make sure that all the poles and zeros in your model appear in the root locus plot. Use the Limits pane, shown below, to override the default settings.

To change the limits, specify the new limits in the real and imaginary axes Limits fields. The Auto-Scale check box automatically clears once you click in a different field. Your root locus diagram updates immediately. If you want to reapply the default limits, select the Auto-Scale check boxes again.

The Limit Stack pane provides support for storing and retrieving custom limit specifications. There are four buttons available:

— Add the current limits to the stack

— Retrieve the previous stack entry

— Retrieve the next stack entry

— Remove the current limits from the stack

Using these buttons, you can store and retrieve any number of saved custom axes limits.

Options Pane

The Options pane contains settings for adding a grid and changing the plot's aspect ratio.

Select Show grid to display a grid on the root locus. If you have damping ratio constraints on your root locus, selecting Display damping ratios as % peak overshoot displays the damping ratio values along the grid lines. This figure shows both options activated for an imported model, Gservo. If you want to verify these settings, type

load ltiexamples 

at the MATLAB® prompt and import Gservo from the workspace into your SISO Design Tool.

The numbers displayed on the root locus gridlines are the damping ratios as a percentage of the overshoot values.

If you select the Equal check box in the Aspect Ratio pane, the x and y-axes are set to equal limit values.

Open-Loop Bode Property Editor

As is the case with the root locus Property Editor, there are three ways to open the Bode diagram property editor:

  • Double-click in the Bode magnitude or phase plot away from the curve.

  • Select Properties from the right-click menu.

  • Select Open-Loop Bode and then Properties from Edit in the menu bar.

This figure shows the Property Editor: Open-Loop Bode editor.

Labels Pane

You can use the Label pane to specify plot titles and axis labels. To specify a new label, type the string in the appropriate field. The Bode diagram automatically updates.

Limits Pane

You can use the Limits pane to override the default limits for the frequency, magnitude, and phase scales for your plots.

To change the limits, specify the new values in the Limits fields for frequency, magnitude, and phase. The Auto-Scale check box automatically deactivates once you click in a different field. The Bode diagram updates immediately.

To restore the default settings, select the Auto-Scale boxes again.

Open-Loop Nichols Property Editor

As is the case with the root locus Property Editor, there are three ways to open the Nichols plot property editor:

  • Double-click in the Nichols plot away from the curve.

  • Select Properties from the right-click menu.

  • Select Open-Loop Nichols and then Properties from Edit in the menu bar.

This figure shows the Property Editor: Open-Loop Nichols editor.

Labels Pane

You can use the Label pane to specify plot titles and axis labels. To specify a new label, type the string in the appropriate field. The Nichols plot automatically updates.

Limits Pane

You can use the Limits pane to override the default limits for the frequency, magnitude, and phase scales for your plots.

To change the limits, specify the new values in the Limits fields for open-loop phase and/or gain. The Auto-Scale check box automatically deactivates once you click in a different field. The Nichols plot updates immediately.

To restore the default settings, select the Auto-Scale boxes again.

Prefilter Bode Property Editor

The Prefilter Bode Property editor is identical to the Open-Loop Bode diagram property editor. There are three ways to open the prefilter editor:

  • Double-click in the prefilter Bode magnitude or phase plot away from the curve.

  • Select Properties from the right-click menu.

  • Select Prefilter Bode and then Properties from Edit in the menu bar.

See Open-Loop Bode Property Editor for a description of the features of this editor.

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