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Nichols Plot

Nichols plot of linear system approximated from nonlinear Simulink model

Library

Simulink® Control Design™

  • Nichols Plot block

Description

This block is the same as the Check Nichols Characteristics block except for different default parameter settings in the Bounds tab.

Compute a linear system from a nonlinear Simulink model and plot the linear system on a Nichols plot.

During simulation, the software linearizes the portion of the model between specified linearization inputs and outputs, and plots the open-loop gain and phase of the linear system.

The Simulink model can be continuous- or discrete-time or multirate and can have time delays. Because you can specify only one linearization input/output pair in this block, the linear system is Single-Input Single-Output (SISO).

You can specify multiple open- and closed-loop gain and phase bounds and view them on the Nichols plot. You can also check that the bounds are satisfied during simulation:

  • If all bounds are satisfied, the block does nothing.

  • If a bound is not satisfied, the block asserts and a warning message appears in the MATLAB® Command Window. You can also specify that the block:

    • Evaluate a MATLAB expression.

    • Stop the simulation and bring that block into focus.

During simulation, the block can also output a logical assertion signal.

  • If all bounds are satisfied, the signal is true (1).

  • If any bound is not satisfied, the signal is false (0).

You can add multiple Nichols Plot blocks to compute and plot the gains and phases of various portions of the model.

You can save the linear system as a variable in the MATLAB workspace.

The block does not support code generation and can be used only in Normal simulation mode.

Parameters

The following table summarizes the Nichols Plot block parameters, accessible via the block parameter dialog box.

TaskParameters
Configure linearization.Specify inputs and outputs (I/Os).

In Linearizations tab:

Specify settings.

In Linearizations tab:

Specify algorithm options.

In Algorithm Options of Linearizations tab:

Specify labels for linear system I/Os and state names.

In Labels of Linearizations tab:

Plot the linear system.Show Plot
Specify the feedback sign for closed-loop gain and phase margins.Feedback sign in Bounds tab.
(Optional) Specify bounds on gains and phases of the linear system for assertion.

In Bounds tab:

Specify assertion options (only when you specify bounds on the linear system).

In Assertion tab:

Save linear system to MATLAB workspace.Save data to workspace in Logging tab.
Display plot window instead of block parameters dialog box on double-clicking the block.Show plot on block open.

Linearization inputs/outputs

Linearization inputs and outputs that define the portion of a nonlinear Simulink model to linearize.

If you have defined the linearization input and output in the Simulink model, the block automatically detects these points and displays them in the Linearization inputs/outputs area. Click at any time to update the Linearization inputs/outputs table with I/Os from the model. To add other analysis points:

  1. Click .

    The dialog box expands to display a Click a signal in the model to select it area and a new button.

  2. Select one or more signals in the Simulink Editor.

    The selected signals appear under Model signal in the Click a signal in the model to select it area.

  3. (Optional) For buses, expand the bus signal to select individual elements.

    Tip

    For large buses or other large lists of signals, you can enter search text for filtering element names in the Filter by name edit box. The name match is case-sensitive. Additionally, you can enter a MATLAB regular expression.

    To modify the filtering options, click . To hide the filtering options, click .

     Filtering Options

  4. Click to add the selected signals to the Linearization inputs/outputs table.

    To remove a signal from the Linearization inputs/outputs table, select the signal and click .

    Tip

    To find the location in the Simulink model corresponding to a signal in the Linearization inputs/outputs table, select the signal in the table and click .

The table displays the following information about the selected signal:

Block : Port : Bus ElementName of the block associated with the input/output. The number adjacent to the block name is the port number where the selected bus signal is located. The last entry is the selected bus element name.
Configuration

Type of linearization point:

  • Open-loop Input — Specifies a linearization input point after a loop opening.

  • Open-loop Output — Specifies a linearization output point before a loop opening.

  • Loop Transfer — Specifies an output point before a loop opening followed by an input.

  • Input Perturbation — Specifies an additive input to a signal.

  • Output Measurement — Takes measurement at a signal.

  • Loop Break — Specifies a loop opening.

  • Sensitivity — Specifies an additive input followed by an output measurement.

  • Complementary Sensitivity — Specifies an output followed by an additive input.

Note

If you simulate the model without specifying an input or output, the software does not compute a linear system. Instead, you see a warning message at the MATLAB prompt.

Settings

No default

Command-Line Information

Use getlinio and setlinio to specify linearization inputs and outputs.

Click a signal in the model to select it

Enables signal selection in the Simulink model. Appears only when you click .

When this option appears, you also see the following changes:

  • A new button.

    Use to add a selected signal as a linearization input or output in the Linearization inputs/outputs table. For more information, see Linearization inputs/outputs.

  • changes to .

    Use to collapse the Click a signal in the model to select it area.

Settings

No default

Command-Line Information

Use the getlinio and setlinio commands to select signals as linearization inputs and outputs.

Enable regular expression

Enable the use of MATLAB regular expressions for filtering signal names. For example, entering t$ in the Filter by name edit box displays all signals whose names end with a lowercase t (and their immediate parents). For details, see Regular Expressions.

Settings

Default: On

On

Allow use of MATLAB regular expressions for filtering signal names.

Off

Disable use of MATLAB regular expressions for filtering signal names. Filtering treats the text you enter in the Filter by name edit box as a literal character vector.

Dependencies

Selecting the Options button on the right-hand side of the Filter by name edit box () enables this parameter.

Show filtered results as a flat list

Uses a flat list format to display the list of filtered signals, based on the search text in the Filter by name edit box. The flat list format uses dot notation to reflect the hierarchy of bus signals. The following is an example of a flat list format for a filtered set of nested bus signals.

Settings

Default: Off

On

Display the filtered list of signals using a flat list format, indicating bus hierarchies with dot notation instead of using a tree format.

Off

Display filtered bus hierarchies using a tree format.

Dependencies

Selecting the Options button on the right-hand side of the Filter by name edit box () enables this parameter.

Linearize on

When to compute the linear system during simulation.

Settings

Default: Simulation snapshots

Simulation snapshots

Specific simulation time, specified in Snapshot times.

Use when you:

  • Know one or more times when the model is at a steady-state operating point

  • Want to compute the linear systems at specific times

External trigger

Trigger-based simulation event. Specify the trigger type in Trigger type.

Use when a signal generated during simulation indicates steady-state operating point.

Selecting this option adds a trigger port to the block. Use this port to connect the block to the trigger signal.

For example, for an aircraft model, you might want to compute the linear system whenever the fuel mass is a fraction of the maximum fuel mass. In this case, model this condition as an external trigger.

Dependencies

  • Setting this parameter to Simulation snapshots enables Snapshot times.

  • Setting this parameter to External trigger enables Trigger type.

Command-Line Information
Parameter: LinearizeAt
Type: character vector
Value: 'SnapshotTimes' | 'ExternalTrigger'
Default: 'SnapshotTimes'

Snapshot times

One or more simulation times. The linear system is computed at these times.

Settings

Default: 0

  • For a different simulation time, enter the time. Use when you:

    • Want to plot the linear system at a specific time

    • Know the approximate time when the model reaches steady-state operating point

  • For multiple simulation times, enter a vector. Use when you want to compute and plot linear systems at multiple times.

Snapshot times must be less than or equal to the simulation time specified in the Simulink model.

Dependencies

Selecting Simulation snapshots in Linearize on enables this parameter.

Command-Line Information
Parameter: SnapshotTimes
Type: character vector
Value: 0 | positive real number | vector of positive real numbers
Default: 0

Trigger type

Trigger type of an external trigger for computing linear system.

Settings

Default: Rising edge

Rising edge

Rising edge of the external trigger signal.

Falling edge

Falling edge of the external trigger signal.

Dependencies

Selecting External trigger in Linearize on enables this parameter.

Command-Line Information
Parameter: TriggerType
Type: character vector
Value: 'rising' | 'falling'
Default: 'rising'

Enable zero-crossing detection

Enable zero-crossing detection to ensure that the software computes the linear system characteristics at the following simulation times:

  • The exact snapshot times, specified in Snapshot times.

    As shown in the following figure, when zero-crossing detection is enabled, the variable-step Simulink solver simulates the model at the snapshot time Tsnap. Tsnap may lie between the simulation time steps Tn-1 and Tn which are automatically chosen by the solver.

  • The exact times when an external trigger is detected, specified in Trigger type.

    As shown in the following figure, when zero-crossing detection is enabled, the variable-step Simulink solver simulates the model at the time, Ttrig, when the trigger signal is detected. Ttrig may lie between the simulation time steps Tn-1 and Tn which are automatically chosen by the solver.

For more information on zero-crossing detection, see Zero-Crossing Detection in the Simulink User Guide.

Settings

Default: On

On

Compute linear system characteristics at the exact snapshot time or exact time when a trigger signal is detected.

This setting is ignored if the Simulink solver is fixed step.

Off

Compute linear system characteristics at the simulation time steps that the variable-step solver chooses. The software may not compute the linear system at the exact snapshot time or exact time when a trigger signal is detected.

Command-Line Information
Parameter: ZeroCross
Type: character vector
Value: 'on' | 'off'
Default: 'on'

Use exact delays

How to represent time delays in your linear model.

Use this option if you have blocks in your model that have time delays.

Settings

Default: Off

On

Return a linear model with exact delay representations.

Off

Return a linear model with Padé approximations of delays, as specified in your Transport Delay and Variable Transport Delay blocks.

Command-Line Information
Parameter: UseExactDelayModel
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Linear system sample time

Sample time of the linear system computed during simulation.

Use this parameter to:

  • Compute a discrete-time system with a specific sample time from a continuous-time system

  • Resample a discrete-time system with a different sample time

  • Compute a continuous-time system from a discrete-time system

When computing discrete-time systems from continuous-time systems and vice-versa, the software uses the conversion method specified in Sample time rate conversion method.

Settings

Default: auto

auto. Computes the sample time as:

  • 0, for continuous-time models.

  • For models that have blocks with different sample times (multirate models), least common multiple of the sample times. For example, if you have a mix of continuous-time and discrete-time blocks with sample times of 0, 0.2 and 0.3, the sample time of the linear model is 0.6.

Positive finite value. Use to compute:

  • A discrete-time linear system from a continuous-time system.

  • A discrete-time linear system from another discrete-time system with a different sample time

0

Use to compute a continuous-time linear system from a discrete-time model.

Command-Line Information
Parameter: SampleTime
Type: character vector
Value: 'auto' | Positive finite value | '0'
Default: 'auto'

Sample time rate conversion method

Method for converting the sample time of single-rate or multirate models.

This parameter is used only when the value of Linear system sample time is not auto.

Settings

Default: Zero-Order Hold

Zero-Order Hold

Zero-order hold, where the control inputs are assumed piecewise constant over the sampling time Ts. For more information, see Zero-Order Hold.

This method usually performs better in the time domain.

Tustin (bilinear)

Bilinear (Tustin) approximation without frequency prewarping. The software rounds off fractional time delays to the nearest multiple of the sampling time. For more information, see Tustin Approximation.

This method usually performs better in the frequency domain.

Tustin with Prewarping

Bilinear (Tustin) approximation with frequency prewarping. Also specify the prewarp frequency in Prewarp frequency (rad/s). For more information, see Tustin Approximation.

This method usually performs better in the frequency domain. Use this method to ensure matching at frequency region of interest.

Upsampling when possible, Zero-Order Hold otherwise

Upsample a discrete-time system when possible and use Zero-Order Hold otherwise.

You can upsample only when you convert a discrete-time system to a new faster sample time that is an integer multiple of the sample time of the original system.

Upsampling when possible, Tustin otherwise

Upsample a discrete-time system when possible and use Tustin (bilinear) otherwise.

You can upsample only when you convert a discrete-time system to a new faster sample time that is an integer multiple of the sample time of the original system.

Upsampling when possible, Tustin with Prewarping otherwise

Upsample a discrete-time system when possible and use Tustin with Prewarping otherwise. Also, specify the prewarp frequency in Prewarp frequency (rad/s).

You can upsample only when you convert a discrete-time system to a new faster sample time that is an integer multiple of the sample time of the original system.

Dependencies

Selecting either:

  • Tustin with Prewarping

  • Upsampling when possible, Tustin with Prewarping otherwise

enables Prewarp frequency (rad/s).

Command-Line Information
Parameter: RateConversionMethod
Type: character vector
Value: 'zoh' | 'tustin' | 'prewarp'| 'upsampling_zoh'| 'upsampling_tustin'| 'upsampling_prewarp'
Default: 'zoh'

Prewarp frequency (rad/s)

Prewarp frequency for Tustin method, specified in radians/second.

Settings

Default: 10

Positive scalar value, smaller than the Nyquist frequency before and after resampling. A value of 0 corresponds to the standard Tustin method without frequency prewarping.

Dependencies

Selecting either

  • Tustin with Prewarping

  • Upsampling when possible, Tustin with Prewarping otherwise

in Sample time rate conversion method enables this parameter.

Command-Line Information
Parameter: PreWarpFreq
Type: character vector
Value: 10 | positive scalar value
Default: 10

Use full block names

How the state, input and output names appear in the linear system computed during simulation.

The linear system is a state-space object, and system states and input/output names appear in following state-space object properties:

Input, Output or State NameAppears in Which State-Space Object Property
Linearization input nameInputName
Linearization output nameOutputName
State namesStateName
Settings

Default: Off

On

Show state and input/output names with their path through the model hierarchy. For example, in the scdcstr model used in the Plot Linear System Characteristics of a Chemical Reactor example, a state in the Integrator1 block of the CSTR subsystem appears with full path as scdcstr/CSTR/Integrator1.

Off

Show only state and input/output names. Use this option when the signal name is unique and you know where the signal is location in your Simulink model. For example, a state in the Integrator1 block of the CSTR subsystem appears as Integrator1.

Command-Line Information
Parameter: UseFullBlockNameLabels
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Use bus signal names

How to label signals associated with linearization inputs and outputs on buses, in the linear system computed during simulation (applies only when you select an entire bus as an I/O point).

Selecting an entire bus signal is not recommended. Instead, select individual bus elements.

You cannot use this parameter when your model has mux/bus mixtures.

Settings

Default: Off

On

Use the signal names of the individual bus elements.

Bus signal names appear when the input and output are at the output of the following blocks:

  • Root-level inport block containing a bus object

  • Bus creator block

  • Subsystem block whose source traces back to one of the following blocks:

    • Output of a bus creator block

    • Root-level inport block by passing through only virtual or nonvirtual subsystem boundaries

Off

Use the bus signal channel number.

Command-Line Information
Parameter: UseBusSignalLabels
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Include gain and phase margins in assertion

Check that the gain and phase margins are greater than the values specified in Gain margin (dB) > and Phase margin (deg) >, during simulation. The software displays a warning if the gain or phase margin is less than or equal to the specified value.

By default, negative feedback, specified in Feedback sign, is used to compute the margins.

This parameter is used for assertion only if Enable assertion in the Assertion tab is selected.

You can specify multiple gain and phase margin bounds on the linear system. The bounds also appear on the Nichols plot. If you clear Enable assertion, the bounds are not used for assertion but continue to appear on the plot.

Settings

Default:

  • Off for Nichols Plot block.

  • On for Check Nichols Characteristics block.

On

Check that the gain and phase margins satisfy the specified values, during simulation.

Off

Do not check that the gain and phase margins satisfy the specified values, during simulation.

Tips

  • Clearing this parameter disables the gain and phase margin bounds and the software stops checking that the gain and phase margins satisfy the bounds during simulation. The bounds are also greyed out on the plot.

  • To only view the gain and phase margin on the plot, clear Enable assertion.

Command-Line Information
Parameter: EnableMargins
Type: character vector
Value: 'on' | 'off'
Default: 'off' for Nichols Plot block, 'on' for Check Nichols Characteristics block

Gain margin (dB) >

Gain margin, in decibels.

By default, negative feedback, specified in Feedback sign, is used to compute the gain margin.

Settings

Default:

[] for Nichols Plot block.
20 for Check Nichols Characteristics block.

  • Positive finite number for one bound.

  • Cell array of positive finite numbers for multiple bounds.

Tips

  • To assert that the gain margin is satisfied, select both Include gain and phase margins in assertion and Enable assertion.

  • You can add or modify gain margins from the plot window:

    • To add new gain margin, right-click the plot, and select Bounds > New Bound. Select Gain margin in Design requirement type, and specify the margin in Gain margin.

    • To modify the gain margin, drag the segment. Alternatively, right-click the plot, and select Bounds > Edit Bound. Specify the new gain margin in Gain margin >.

    You must click Update Block before simulating the model.

Command-Line Information
Parameter: GainMargin
Type: character vector
Value: [] | 20 | positive finite value. Must be specified inside single quotes ('').
Default: '[]' for Nichols Plot block, '20' for Check Nichols Characteristics block.

Phase margin (deg) >

Phase margin, in degrees.

By default, negative feedback, specified in Feedback sign, is used to compute the phase margin.

Settings
[] for Nichols Plot block.
30 for Check Nichols Characteristics block.

  • Positive finite number for one bound.

  • Cell array of positive finite numbers for multiple bounds.

Tips

  • To assert that the phase margin is satisfied, select both Include gain and phase margins in assertion and Enable assertion.

  • You can add or modify phase margins from the plot window:

    • To add new phase margin, right-click the plot, and select Bounds > New Bound. Select Phase margin in Design requirement type, and specify the margin in Phase margin.

    • To modify the phase margin, drag the segment. Alternatively, right-click the bound, and select Bounds > Edit Bound. Specify the new phase margin in Phase margin >.

    You must click Update Block before simulating the model.

Command-Line Information
Parameter: PhaseMargin
Type: character vector
Value: [] | 30 | positive finite value. Must be specified inside single quotes ('').
Default: '[]' for Nichols Plot block, '30' for Check Nichols Characteristics block.

Include closed-loop peak gain in assertion

Check that the closed-loop peak gain is less than the value specified in Closed-loop peak gain (dB) <, during simulation. The software displays a warning if the closed-loop peak gain is greater than or equal to the specified value.

By default, negative feedback, specified in Feedback sign, is used to compute the closed-loop peak gain.

This parameter is used for assertion only if Enable assertion in the Assertion tab is selected.

You can specify multiple closed-loop peak gain bounds on the linear system. The bound also appear on the Nichols plot as an m-circle. If you clear Enable assertion, the bounds are not used for assertion but continue to appear on the plot.

Settings

Default: Off

On

Check that the closed-loop peak gain satisfies the specified value, during simulation.

Off

Do not check that the closed-loop peak gain satisfies the specified value, during simulation.

Tips

  • Clearing this parameter disables the closed-loop peak gain bound and the software stops checking that the peak gain satisfies the bounds during simulation. The bounds are greyed out on the plot.

  • To only view the closed-loop peak gain on the plot, clear Enable assertion.

Command-Line Information
Parameter: EnableCLPeakGain
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Closed-loop peak gain (dB) <

Closed-loop peak gain, in decibels.

By default, negative feedback, specified in Feedback sign, is used to compute the margins.

Settings

Default []

  • Positive or negative finite number for one bound.

  • Cell array of positive or negative finite numbers for multiple bounds.

Tips

  • To assert that the gain margin is satisfied, select both Include closed-loop peak gain in assertion and Enable assertion.

  • You can add or modify closed-loop peak gains from the plot window:

    • To add the closed-loop peak gain, right-click the plot, and select Bounds > New Bound. Select Closed-Loop peak gain in Design requirement type, and specify the gain in Closed-Loop peak gain <.

    • To modify the closed-loop peak gain, drag the segment. Alternatively, right-click the bound, and select Bounds > Edit Bound. Specify the new closed-loop peak gain in Closed-Loop peak gain <.

    You must click Update Block before simulating the model.

Command-Line Information
Parameter: CLPeakGain
Type: character vector
Value: [] | positive or negative number | cell array of positive or negative numbers. Must be specified inside single quotes ('').
Default: '[]'

Include open-loop gain-phase bound in assertion

Check that the Nichols response satisfies open-loop gain and phase bounds, specified in Open-loop phases (deg) and Open-loop gains (dB), during simulation. The software displays a warning if the Nichols response violates the bounds.

This parameter is used for assertion only if Enable assertion in the Assertion tab is selected.

You can specify multiple gain and phase bounds on the linear systems computed during simulation. The bounds also appear on the Nichols plot. If you clear Enable assertion, the bounds are not used for assertion but continue to appear on the plot.

Settings

Default: Off

On

Check if the Nichols response satisfies the specified open-loop gain and phase bounds, during simulation.

Off

Do not check if the Nichols response satisfies the specified open-loop gain and phase bounds, during simulation.

Tips

  • Clearing this parameter disables the gain-phase bound and the software stops checking that the gain and phase satisfy the bound during simulation. The bound segments are also greyed out on the plot.

  • To only view the bound on the plot, clear Enable assertion.

Command-Line Information
Parameter: EnableGainPhaseBound
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Open-loop phases (deg)

Open-loop phases, in degrees.

Specify the corresponding open-loop gains in Open-loop gains (dB).

Settings

Default: []

Must be specified as start and end phases:

  • Positive or negative finite numbers for a single bound with one edge

  • Matrix of positive or negative finite numbers , for a single bound with multiple edges

  • Cell array of matrices with finite numbers for multiple bounds

Tips

  • To assert that the open-loop gains and phases are satisfied, select both Include open-loop gain-phase bound in assertion and Enable assertion.

  • You can add or modify open-loop phases from the plot window:

    • To add a new phases, right-click the plot, and select Bounds > New Bound. Select Gain-Phase requirement in Design requirement type, and specify the phases in the Open-Loop phase column. Specify the corresponding gains in the Open-Loop gain column.

    • To modify the phases, drag the bound segment. Alternatively, right-click the segment, and select Bounds > Edit Bounds. Specify the new phases in the Open-Loop phase column.

    You must click Update Block before simulating the model.

Command-Line Information
Parameter: OLPhases
Type: character vector
Value: [] | positive or negative finite numbers | matrix of positive or negative finite numbers | cell array of matrices with finite numbers. Must be specified inside single quotes ('').
Default: '[]'

Open-loop gains (dB)

Open-loop gains, in decibels.

Specify the corresponding open-loop phases in Open-loop phases (deg).

Settings

Default: []

Must be specified as start and end gains:

  • Positive or negative number for a single bound with one edge

  • Matrix of positive or negative finite numbers for a single bound with multiple edges

  • Cell array of matrices with finite numbers for multiple bounds

Tips

  • To assert that the open-loop gains are satisfied, select both Include open-loop gain-phase bound in assertion and Enable assertion.

  • You can add or modify open-loop gains from the plot window:

    • To add a new gains, right-click the plot, and select Bounds > New Bound. Select Gain-Phase requirement in Design requirement type, and specify the gains in the Open-Loop phase column. Specify the phases in the Open-Loop phase column.

    • To modify the gains, drag the bound segment. Alternatively, right-click the segment, and select Bounds > Edit Bounds. Specify the new gains in the Open-Loop gain column.

    You must click Update Block before simulating the model.

Command-Line Information
Parameter: OLGains
Type: character vector
Value: [] | positive or negative number | matrix of positive or negative finite numbers | cell array of matrices with finite numbers. Must be specified inside single quotes ('').
Default: '[]'

Feedback sign

Feedback sign to determine the closed-loop gain and phase characteristics of the linear system, computed during simulation.

To determine the feedback sign, check if the path defined by the linearization inputs and outputs include the feedback Sum block:

  • If the path includes the Sum block, specify positive feedback.

  • If the path does not include the Sum block, specify the same feedback sign as the Sum block.

Settings

Default: negative feedback

negative feedback

Use when the path defined by the linearization inputs/outputs does not include the Sum block and the Sum block feedback sign is -.

positive feedback

Use when:

  • The path defined by the linearization inputs/outputs includes the Sum block.

  • The path defined by the linearization inputs/outputs does not include the Sum block and the Sum block feedback sign is +.

Command-Line Information
Parameter: FeedbackSign
Type: character vector
Value: '-1' | '+1'
Default: '-1'

Save data to workspace

Save one or more linear systems to perform further linear analysis or control design.

The saved data is in a structure whose fields include:

  • time — Simulation times at which the linear systems are computed.

  • values — State-space model representing the linear system. If the linear system is computed at multiple simulation times, values is an array of state-space models.

  • operatingPoints — Operating points corresponding to each linear system in values. This field exists only if Save operating points for each linearization is checked.

The location of the saved data structure depends upon the configuration of the Simulink model:

  • If the Simulink model is not configured to save simulation output as a single object, the data structure is a variable in the MATLAB workspace.

  • If the Simulink model is configured to save simulation output as a single object, the data structure is a field in the Simulink.SimulationOutput object that contains the logged simulation data.

    To configure your model to save simulation output in a single object, in the Simulink editor, on the Modeling tab, click Model Settings. Then, in the Configuration Parameters dialog box, select the Single simulation output parameter.

For more information about data logging in Simulink, see Save Simulation Data and the Simulink.SimulationOutput reference page.

Settings

Default: Off

On

Save the computed linear system.

Off

Do not save the computed linear system.

Dependencies

This parameter enables Variable name.

Command-Line Information
Parameter: SaveToWorkspace
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Variable name

Name of the data structure that stores one or more linear systems computed during simulation.

The location of the saved data structure depends upon the configuration of the Simulink model:

  • If the Simulink model is not configured to save simulation output as a single object, the data structure is a variable in the MATLAB workspace.

  • If the Simulink model is configured to save simulation output as a single object, the data structure is a field in the Simulink.SimulationOutput object that contains the logged simulation data.

The name must be unique among the variable names used in all data logging model blocks, such as Linear Analysis Plot blocks, Model Verification blocks, Scope blocks, To Workspace blocks, and simulation return variables such as time, states, and outputs.

For more information about data logging in Simulink, see Save Simulation Data and the Simulink.SimulationOutput reference page.

Settings

Default: sys

Character vector.

Dependencies

Save data to workspace enables this parameter.

Command-Line Information
Parameter: SaveName
Type: character vector
Value: sys | any character vector. Must be specified inside single quotes ('').
Default: 'sys'

Save operating points for each linearization

When saving linear systems to the workspace for further analysis or control design, also save the operating point corresponding to each linearization. Using this option adds a field named operatingPoints to the data structure that stores the saved linear systems.

Settings

Default: Off

On

Save the operating points.

Off

Do not save the operating points.

Dependencies

Save data to workspace enables this parameter.

Command-Line Information
Parameter: SaveOperatingPoint
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Enable assertion

Enable the block to check that bounds specified and included for assertion in the Bounds tab are satisfied during simulation. Assertion fails if a bound is not satisfied. A warning, reporting the assertion failure, appears at the MATLAB prompt.

If assertion fails, you can optionally specify that the block:

For the Linear Analysis Plots blocks, this parameter has no effect because no bounds are included by default. If you want to use the Linear Analysis Plots blocks for assertion, specify and include bounds in the Bounds tab.

Clearing this parameter disables assertion; that is, the block no longer checks that specified bounds are satisfied. The block icon also updates to indicate that assertion is disabled.

In the Simulink model, in the Configuration Parameters dialog box, the Model Verification block enabling parameter lets you enable or disable all model verification blocks in a model, regardless of the setting of this option in the block.

Settings

Default: On

On

Check that bounds included for assertion in the Bounds tab are satisfied during simulation. A warning, reporting assertion failure, is displayed at the MATLAB prompt if bounds are violated.

Off

Do not check that bounds included for assertion are satisfied during simulation.

Dependencies

This parameter enables:

  • Simulation callback when assertion fails (optional)

  • Stop simulation when assertion fails

Command-Line Information
Parameter: enabled
Type: character vector
Value: 'on' | 'off'
Default: 'on'

Simulation callback when assertion fails (optional)

MATLAB expression to execute when assertion fails.

Because the expression is evaluated in the MATLAB workspace, define all variables used in the expression in that workspace.

Settings

No Default

A MATLAB expression.

Dependencies

Enable assertion enables this parameter.

Command-Line Information
Parameter: callback
Type: character vector
Value: '' | MATLAB expression
Default: ''

Stop simulation when assertion fails

Stop the simulation when a bound specified in the Bounds tab is violated during simulation, i.e., assertion fails.

If you run the simulation from the Simulink Editor, the Simulation Diagnostics window opens to display an error message. Also, the block where the bound violation occurs is highlighted in the model.

Settings

Default: Off

On

Stop simulation if a bound specified in the Bounds tab is violated.

Off

Continue simulation if a bound is violated with a warning message at the MATLAB prompt.

Tips

  • Because selecting this option stops the simulation as soon as the assertion fails, assertion failures that might occur later during the simulation are not reported. If you want all assertion failures to be reported, do not select this option.

Dependencies

Enable assertion enables this parameter.

Command-Line Information
Parameter: stopWhenAssertionFail
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Output assertion signal

Output a Boolean signal that, at each time step, is:

  • True (1) if assertion succeeds; that is, all bounds are satisfied

  • False (1) if assertion fails; that is, a bound is violated.

The output signal data type is Boolean only if, in the Simulink model, in the Configuration Parameters dialog box, the Implement logic signals as Boolean data parameter is selected. Otherwise, the data type of the output signal is double.

Selecting this parameter adds an output port to the block that you can connect to any block in the model.

Settings

Default:Off

On

Output a Boolean signal to indicate assertion status. Adds a port to the block.

Off

Do not output a Boolean signal to indicate assertion status.

Tips
Command-Line Information
Parameter: export
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Show plot on block open

Open the plot window instead of the Block Parameters dialog box when you double-click the block in the Simulink model.

Use this parameter if you prefer to open and perform tasks, such as adding or modifying bounds, in the plot window instead of the Block Parameters dialog box. If you want to access the block parameters from the plot window, select Edit or click .

For more information on the plot, see Show Plot.

Settings

Default: Off

On

Open the plot window when you double-click the block.

Off

Open the Block Parameters dialog box when you double-click the block.

Command-Line Information
Parameter: LaunchViewOnOpen
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Show Plot

Open the plot window.

Use the plot to view:

  • System characteristics and signals computed during simulation

    You must click this button before you simulate the model to view the system characteristics or signal.

    You can display additional characteristics, such as the peak response time, by right-clicking the plot and selecting Characteristics.

  • Bounds

    You can specify bounds in the Bounds tab of the Block Parameters dialog box or right-click the plot and select Bounds > New Bound. For more information on the types of bounds you can specify, see the individual reference pages.

    You can modify bounds by dragging the bound segment or by right-clicking the plot and selecting Bounds > Edit Bound. Before you simulate the model, click Update Block to update the bound value in the block parameters.

Typical tasks that you perform in the plot window include:

  • Opening the Block Parameters dialog box by clicking or selecting Edit.

  • Finding the block that the plot window corresponds to by clicking or selecting View > Highlight Simulink Block. This action makes the model window active and highlights the block.

  • Simulating the model by clicking . This action also linearizes the portion of the model between the specified linearization input and output.

  • Adding a legend on the linear system characteristic plot by clicking .

Note

To optimize the model response to meet design requirements specified in the Bounds tab, open the Response Optimizer by selecting Tools > Response Optimization in the plot window. This option is only available if you have Simulink Design Optimization™ software installed.

Response Optimization

Open the Response Optimizer to optimize the model response to meet design requirements specified in the Bounds tab.

This button is available only if you have Simulink Design Optimization software installed.

Version History

Introduced in R2010b