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diskmarginoptions

Customize disk-based stability-margin plots

Description

example

opts = diskmarginoptions returns the default option set for plots you generate with diskmarginplot and wcdiskmarginplot. You can then use dot notation to change option values. Use opts to customize the plot appearance.

example

opts = diskmarginoptions('cstprefs') initializes the plot options with the options you have specified in the Control System Toolbox™ Preferences Editor. For more information about the editor, see Toolbox Preferences Editor.

Examples

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Plot the disk margins as a function of frequency of a system with the following open-loop response.

L = tf(25,[1 10 10 10]);

For the plot, specify the following attributes:

  • Frequency units: Hz

  • Gain margins on a log scale, in absolute units

  • Grid on

opts = diskmarginoptions;
opts.FreqUnits = 'Hz';
opts.MagScale = 'log';
opts.MagUnits = 'abs';
opts.grid = 'on';

diskmarginplot(L,opts)

Figure contains 2 axes. Axes 1 contains an object of type line. This object represents L. Axes 2 contains an object of type line. This object represents L.

Plot the worst-case disk margins as a function of frequency of a system with the following open-loop response.

a  = ureal('a',10,'PlusMinus',[-4,4]);
L = tf(25,[1 a a a]);

For the plot, use the default preferences specified in your Control System Toolbox preference, except specify the following attributes:

  • Frequency units: Hz

  • Gain margins on a log scale, in absolute units

  • Grid on

opts = diskmarginoptions('cstprefs');
opts.FreqUnits = 'Hz';
opts.MagScale = 'log';
opts.MagUnits = 'abs';
opts.grid = 'on';

w = {2*pi*1e-3,2*pi*10};   % rad/s
wcdiskmarginplot(L,w,opts)

Figure contains 2 axes. Axes 1 contains 25 objects of type line. These objects represent Sampled uncertainty, Nominal, Worst perturbation, Worst-case margin (lower bound), Worst-case margin (upper bound). Axes 2 contains 25 objects of type line. These objects represent Sampled uncertainty, Nominal, Worst perturbation, Worst-case margin (lower bound), Worst-case margin (upper bound).

The plot you obtain might differ in appearance, depending on your current Control System Toolbox preference settings. (See Toolbox Preferences Editor.)

Output Arguments

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Options for disk-margin plots of dynamic systems, returned as a diskmarginplot options set. Initialize the value of opts with either default options or the values specified in the Control System Toolbox preferences editor. Customize the option values using dot notation. Then, use opts with diskmarginplot or wcdiskmarginplot to customize plots of the disk-based stability margins of dynamic systems. The following table lists the available options.

Option Description
FreqUnits

Frequency units, specified as one of the following:

  • 'rad/second' (default)

  • 'auto' — Use frequency units rad/TimeUnit relative to system time units specified in the TimeUnit property of the dynamic system.

  • 'Hz'

  • 'rpm'

  • 'kHz'

  • 'MHz'

  • 'GHz'

  • 'rad/nanosecond'

  • 'rad/microsecond'

  • 'rad/millisecond'

  • 'rad/minute'

  • 'rad/hour'

  • 'rad/day'

  • 'rad/week'

  • 'rad/month'

  • 'rad/year'

  • 'cycles/nanosecond'

  • 'cycles/microsecond'

  • 'cycles/millisecond'

  • 'cycles/hour'

  • 'cycles/day'

  • 'cycles/week'

  • 'cycles/month'

  • 'cycles/year'

FreqScale

Frequency scale, specified as:

  • 'log' (default)

  • 'linear'

MagUnits

Units of gain margin, specified as:

  • 'dB' (default)

  • 'abs' — Absolute units

MagScale

Scale of gain-margin plot, specified as:

  • 'linear' (default)

  • 'log'

PhaseUnits

Units of phase margin, specified as:

  • 'deg' (default)

  • 'rad'

Title, XLabel, YLabel

Title and axis label text and style, specified as a structure with the following fields:

  • String — Label of the title, x-axis, or y-axis

  • FontSize

  • FontWeight'Normal' (default) or 'Bold'

  • FontAngle'Normal' (default) or 'Italic'

  • 'Color'[0 0 0] (default)

  • Interpreter'tex' (default)

TickLabel

Tick label style, specified as a structure with the following fields:

  • FontSize

  • FontWeight'Normal' (default) or 'Bold'

  • FontAngle'Normal' (default) or 'Italic'

  • 'Color'[0 0 0] (default)

Grid

Show or hide the grid, specified as:

  • 'off' (default)

  • 'on'

GridColor

Color of grid lines, specified as a vector of RGB values in the range [0,1]. The default value is [0.15,0.15,0.15].

XlimMode, YlimMode

Selection mode for axis limits, specified as:

  • 'auto' (default) — Set axis limits automatically based on plotted data.

  • 'manual' — Specify axis limits using XLim and YLim options.

Xlim, Ylim

Axis limits, specified as a two-element vector of the form [min,max].

Introduced in R2020a