Graphical Tuning Window Preferences Editor

Opening the Graphical Tuning Window Preferences Editor

To open the SISO Tool Preferences editor, select SISO Tool Preferences from the Edit menu of the Graphical Tuning window. This window opens.

Units Pane

The Units pane has settings for the following units:

  • Frequency

    The default units are rad/second.

     Other Frequency Units Options

  • Magnitude — Decibels (dB) or absolute value (abs)

  • Phase — Degrees or radians

For frequency and magnitude axes, you can select logarithmic or linear scales.

Time Delays Pane

In the Time Delays pane, specify the order for Padé approximations of delays in your system as either:

  • Actual Padé order

  • Bandwidth of accuracy (rad/s) — The highest frequency at which the approximated response matches the actual system. The software computes and displays the corresponding Padé order.

The following compensator design tools do not support systems with exact time delays. If your system has exact continuous-time delays, these tools automatically compute a Padé approximation of the delays. In this case, you receive a notification.

  • Root locus

  • Pole-zero

  • PID automated tuning

  • IMC automated tuning

  • LQG automated tuning

  • Loop shaping automated tuning

    Tip   To determine if a certain Padé order gives a good approximation of your system, use the pade command to approximate your system. Then, compare a plot of the two systems using the bode command.

Style Pane

Use the Style pane to toggle grid visibility and set font preferences and axes foreground colors for all plots in the Graphical Tuning Window. This figure shows the Style pane.

Grids Panel

Select the box to activate grids for all plots in the GRAPHICAL Tuning Window

Fonts Panel

Set the font size, weight (bold), and angle (italic) by using the menus and check boxes.

Colors Panel

Specify the color vector to use for the axes foreground, which includes the X-Y axes, grid lines, and tick labels. Use a three-element vector to represent red, green, and blue (RGB) values. Vector element values can range from 0 to 1.

Select colors.  Click the Select button to open the Select Color window for the axes foreground.

You can use this window to choose axes foreground colors without having to set RGB (red-green-blue) values numerically. To make your selections, click on the colored rectangles and press OK. If you want a broader range of colors, click the More Colors button. This opens the More Colors window, as shown in the following figure.

Click on the array of color swatches to select a color. Alternatively, click the HSB tab to use the Hue Saturation Brightness (HSB) color picker. Or, click the RGB tab to enter numeric RGB values.

When you select a color, the Preview section of the window changes to preview your selection. Click OK to accept the choice. Click Reset to reset the selection.

Options Pane

The Options pane, shown below, has selections for compensator format and Bode diagrams.

You can make the following selections:

  • Compensator Format — Select the time constant, natural frequency, or zero/pole/gain format. The time constant format is a factorization of the compensator transfer function of the form


    where DC is compensator DC gain, Tz1, Tz2, ..., are the zero time constants, and Tp1, Tp2, ..., are the pole time constants.

    The natural frequency format is


    where DC is compensator DC gain, ωz1, and ωz2, ... and ωp1, ωp2, ..., are the natural frequencies of the zeros and poles, respectively.

    The zero/pole/gain format is


    where K is the overall compensator gain, and z1, z2, ... and p1, p2, ..., are the zero and pole locations, respectively.

  • Bode Options — By default, the GRAPHICAL Tuning Window shows the plant and sensor poles and zeros as blue x's and o's, respectively. Clear this check box to eliminate the plant's poles and zeros from the Bode plot. Note that the compensator poles and zeros (in red) will still appear.

Line Colors Pane

The Line Colors pane, shown below, has selections for specify the colors of the lines in the response plots of the Graphical Tuning Window.

To change the colors of plot lines associated with parts of your model, specify a three-element vector to represent red, green, and blue (RGB) values. Vector element values can range from 0 to 1.

If you do not want to specify the RGB values numerically, click the Select button to open the Select Color window. See Select colors for more information.

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