# robOptions

Option set for robustness analysis

## Description

## Examples

### Options for Robustness Margin Calculation

Create an options set for a `robstab`

, `robgain`

, or `musynperf`

calculation that displays the progress of the underlying `mussv`

calculation. Also, turn on the element-by-element sensitivity calculation.

opts = robOptions('Display','on','Sensitivity','on');

Alternatively, create a default option set, and use dot notation to set the values of particular options.

opts = robOptions; opts.Display = 'on'; opts.Sensitivity = 'on';

Use `opts`

as an input argument to `robstab`

, `robgain`

, or `musynperf`

.

## Input Arguments

### Name-Value Arguments

Specify optional pairs of arguments as
`Name1=Value1,...,NameN=ValueN`

, where `Name`

is
the argument name and `Value`

is the corresponding value.
Name-value arguments must appear after other arguments, but the order of the
pairs does not matter.

*
Before R2021a, use commas to separate each name and value, and enclose*
`Name`

*in quotes.*

**Example: **`'Display','on','Sensitivity','on'`

`Display`

— Display progress of computation and summary report

`'off'`

(default) | `'on'`

Display progress and summary of the robustness computation,
specified as the comma-separated pair consisting of `'Display'`

and
one of these values:

`'off'`

— Do not display progress and report.`'on'`

— Display progress and report. When you use this option, a progress indicator and summary of results is displayed in the command window, similar to the following.points completed (of 28) ... 28 System is robustly stable for the modeled uncertainty. -- It can tolerate up to 116% of the modeled uncertainty. -- There is a destabilizing perturbation amounting to 117% of the modeled uncertainty. -- This perturbation causes an instability at the frequency 5.9 rad/seconds.

This setting overrides the silent (`'s'`

)
option in the `MussvOptions`

option.

`VaryFrequency`

— Compute robustness margin as function of frequency

`'off'`

(default) | `'on'`

Return robustness margin as a function of frequency, specified
as the comma-separated pair consisting of `'VaryFrequency'`

and
one of these values:

`'off'`

— Only return margins at frequencies where robustness is weakest.`'on'`

— Compute robustness margins over a frequency grid suitable for plotting. The frequency grid is chosen automatically based on system dynamics. This calculation is done in addition to identifying the critical frequency where the margin is weakest. Access the frequency values and corresponding margins in the`info`

output of`robstab`

and`robgain`

.

This option is ignored for `ufrd`

and `genfrd`

models.

`Sensitivity`

— Calculate sensitivity of robustness margin

`'off'`

(default) | `'on'`

Calculate the sensitivity of the robustness margin to each uncertain
element in the model, specified as the comma-separated pair consisting
of `'Sensitivity'`

and either `'off'`

or `'on'`

.

Each uncertain element contributes to the overall stability
margin in a coupled manner. Set this option to `'on'`

to
estimate the sensitivity of the margin to each element. This element-by-element
sensitivity provides an indication of which elements are most problematic
for robustness. Access the sensitivity estimates in the `info`

output
of `robstab`

and `robgain`

.

`SensitivityPercent`

— Percentage variation of uncertainty for computing sensitivity

25 (default) | positive scalar value

Percentage variation of uncertainty level for computing sensitivity,
specified as the comma-separated pair consisting of `'SensitivityPercent'`

and
a positive scalar value. The sensitivity to a particular uncertain
element is estimated using a finite difference calculation. This calculation
increases the (normalized) amount of uncertainty on this element by
some percentage, computes the resulting robustness, and computes the
ratio of percent variations. This option specifies the percentage
increase in uncertainty level applied to each element. The default
value is 25%.

`MussvOptions`

— Options for `mussv`

calculation

`''`

(default) | character vector

Options for the underlying `mussv`

calculation
that `robstab`

and `robgain`

perform,
specified as the comma-separated pair consisting of `'MussvOptions'`

and
a character vector such as `'sm3'`

or `'ad'`

.

Some `MussvOptions`

values that are especially
useful for improving robustness-margin calculations include:

`'a'`

— Force the use of LMI optimization to compute the*μ*upper bound, which yields better results in general but can be expensive when some`ureal`

elements are repeated multiple times.`'mN'`

— Use multiple restarts when computing the*μ*lower bound, which corresponds to the upper bound for robustness margins. This option can reduce the gap between the lower bound and upper bound on the robustness margins.`N`

is the number of restarts. For example, setting`'MussvOptions'`

to`'m3'`

causes three restarts.

See `mussv`

for the remaining
available options and corresponding characters. The default, `''`

,
uses the default options for `mussv`

.

## Output Arguments

`opts`

— Options for robustness commands

`robOptions`

object

Options for robustness commands `robstab`

, `robgain`

,
and `musynperf`

, returned as a
`robOptions`

object. Use the options as
an input argument to `robstab`

,
`robgain`

, or
`musynperf`

. For example:

[stabmarg,wcu,info] = robstab(usys,opts)

## Version History

**Introduced in R2016b**

### R2016b: `robOptions`

replaces `robustperfOptions`

and
`robuststabOptions`

`robOptions`

replaces
`robustperfOptions`

and
`robuststabOptions`

, which are no longer
recommended.

## MATLAB 명령

다음 MATLAB 명령에 해당하는 링크를 클릭했습니다.

명령을 실행하려면 MATLAB 명령 창에 입력하십시오. 웹 브라우저는 MATLAB 명령을 지원하지 않습니다.

Select a Web Site

Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select: .

You can also select a web site from the following list:

## How to Get Best Site Performance

Select the China site (in Chinese or English) for best site performance. Other MathWorks country sites are not optimized for visits from your location.

### Americas

- América Latina (Español)
- Canada (English)
- United States (English)

### Europe

- Belgium (English)
- Denmark (English)
- Deutschland (Deutsch)
- España (Español)
- Finland (English)
- France (Français)
- Ireland (English)
- Italia (Italiano)
- Luxembourg (English)

- Netherlands (English)
- Norway (English)
- Österreich (Deutsch)
- Portugal (English)
- Sweden (English)
- Switzerland
- United Kingdom (English)