Documentation Center

  • Trial Software
  • Product Updates

Check Custom Bounds

Check that signal satisfies upper and lower bounds during simulation

Library

Simulink Design Optimization

Description

Check that a signal satisfies upper and lower bounds 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 at the MATLAB® prompt. 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 a bound is not satisfied, the signal is false (0).

You can add Check Custom Bounds blocks on multiple signals to check that they satisfy the bounds.

You can also plot the bounds on a time plot to graphically verify that the signal satisfies the bounds.

This block and the other blocks in the Model Verification library test that a signal remains within specified time-domain characteristic bounds. When a model does not violate any bound, you can disable the block by clearing the assertion option. If you modify the model, you can re-enable assertion to ensure that your changes do not cause the model to violate a bound.

If the signal does not satisfy the bounds, you can optimize the model parameters to satisfy the bounds. If you have Simulink® Control Design™ software, you can add frequency-domain bounds such as Bode magnitude and optimize the model response to satisfy both time- and frequency-domain requirements.

The block can be used in all simulation modes for signal monitoring but only in Normal or Accelerator simulation mode for response optimization.

Parameters

TaskParameters
Specify upper and lower bounds to:
  • Assert that a signal satisfies the bounds

  • Optimize model response so that a signal satisfies the bounds

In the Bounds tab:
Specify assertion options (only when you specify upper and lower bounds).In the Assertion tab:
Open Design Optimization tool to optimize model responseClick Response Optimization
Plot upper and lower boundsClick Show Plot.
Display plot window instead of Block Parameters dialog box on double-clicking the block.Show plot on block open

Include upper bound in assertion

Check that a signal is less than or equal to upper bounds, specified in Times (seconds) and Amplitudes, during simulation. The software displays a warning if the signal violates the upper bounds.

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

You can specify multiple upper bounds on various model signals. The bounds also appear on the time plot. If you clear Enable assertion, the bounds are not used for assertion but continue to appear on the plot.

Settings

Default: On

On

Check that the signal satisfies the specified upper bounds during simulation.

Off

Do not check that the signal satisfies the specified upper bounds during simulation.

Tips

  • Clearing this parameter disables the upper bounds and the software stops checking that the bounds are satisfied during simulation. The bound segments are also greyed out on the plot.

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

Command-Line Information

Parameter: EnableUpperBound
Type: string
Value: 'on' | 'off'
Default: 'on'

Times (seconds)

Time vector for one or more upper bound segments, specified in seconds.

Specify the corresponding amplitude values in Amplitudes.

Settings

Default: [0 5; 5 10]

Must be specified as start and end times:

  • Positive finite numbers for a single bound with one edge.

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

    For example, type [0.1 1;1 10] for two edges at times [0.1 1] and [1 10].

  • Cell array of matrices with positive finite numbers for multiple bounds.

Tips

  • To assert that amplitudes that correspond to the time vectors are satisfied, select both Include upper bound in assertion and Enable assertion.

  • You can add or modify start and end times from the plot window:

    • To add new time vectors, right-click the yellow area on the plot, and select Edit. Click Insert to add a new row to the Edit Bound dialog box. Specify the start and end times of the new bound segment in the Time column. Specify the corresponding amplitudes in the Amplitude column.

    • To modify the start and end times, drag the bound segment. Alternatively, right-click the segment, and select Edit. Specify the new times in the Time column.

    You must click Update Block before simulating the model.

Command-Line Information

Parameter: UpperBoundTimes
Type: string
Value: [0 5; 5 10] | positive finite numbers | matrix of positive finite numbers | matrix of positive finite numbers cell array of matrices with positive finite numbers. Must be specified inside single quotes ('').
Default: [0 5; 5 10]

Amplitudes

Amplitude values for one or more upper bound segments.

Specify the corresponding start and end times in Times (seconds).

Settings

Default: [1.1 1.1; 1.01 1.01]

Must be specified as start and end amplitudes:

  • Finite numbers for a single bound with one edge

  • Matrix of finite numbers for a single bound with multiple edges.

    For example, type [0 1; 2 3] for two edges at amplitudes [0 1] and [2 3].

  • Cell array of matrices with finite numbers for multiple bounds

Tips

  • To assert that amplitude bounds are satisfied, select both Include upper bound in assertion and Enable assertion.

  • You can add or modify amplitudes from the plot window:

    • To add new amplitudes, right-click the plot, and select Edit. Click Insert to add a new row to the Edit Bound dialog box. Specify the start and end amplitudes of the new bound segment in the Amplitude column. Specify the corresponding start and end times in the Time column.

    • To modify the start and end amplitudes, drag the bound segment. Alternatively, right-click the segment, and select Edit. Specify the new amplitudes in the Amplitude column.

    You must click Update Block before simulating the model.

Command-Line Information

Parameter: UpperBoundAmplitudes
Type: string
Value: [1.1 1.1; 1.01 1.01] | finite numbers | matrix of finite numbers | cell array of matrices with finite numbers. Must be specified inside single quotes ('').
Default: [1.1 1.1; 1.01 1.01]

Include lower bound in assertion

Check that a signal is greater than or equal to lower bounds, specified in Times (seconds) and Amplitudes, during simulation.

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

You can specify multiple lower bounds on various model signals. The bounds also appear on the time 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 that the signal satisfies the specified lower bounds during simulation.

Off

Do not check that the signal satisfies the specified lower bounds during simulation.

Tips

  • Clearing this parameter disables the lower bounds and the software stops checking that the bounds are satisfied during simulation. The bound segments are also greyed out on the plot.

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

Command-Line Information

Parameter: EnableLowerBound
Type: string
Value: 'on' | 'off'
Default: 'off'

Times (seconds)

Time vector for one or more lower bound segments, specified in seconds.

Specify the corresponding amplitude values in Amplitudes

Settings

Default: []

Must be specified as start and end times:

  • Positive finite numbers for a single bound with one edge.

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

    For example, type [0.1 1;1 10] for two edges at times [0.1 1] and [1 10].

  • Cell array of matrices with positive finite numbers for multiple bounds.

Tips

  • To assert that amplitudes that correspond to the time vectors are satisfied, select both Include lower bound in assertion and Enable assertion.

  • You can add or modify start and end times from the plot window:

    • To add new time vectors, right-click the yellow area on the plot, and select Edit. Click Insert to add a new row to the Edit Bound dialog box. Specify the start and end times of the new bound segment in the Time column. Specify the corresponding amplitudes in the Amplitude column.

    • To modify the start and end times, drag the bound segment. Alternatively, right-click the segment, and select Edit. Specify the new times in the Time column.

    You must click Update Block before simulating the model.

Command-Line Information

Parameter: LowerBoundTimes
Type: string
Value: [] | positive finite numbers | matrix of positive finite numbers | cell array of matrices with positive finite numbers. Must be specified inside single quotes ('').
Default: []

Amplitudes

Amplitude values for one or more lower bound segments.

Specify the corresponding start and end times in Times (seconds).

Settings

Default: []

Must be specified as start and end amplitudes:

  • Finite numbers for a single bound with one edge

  • Matrix of finite numbers for a single bound with multiple edges.

    For example, type [0 1; 2 3] for two edges at amplitudes [0 1] and [2 3].

  • Cell array of matrices with finite numbers for multiple bounds

Tips

  • To assert that amplitude bounds are satisfied, select both Include lower bound in assertion and Enable assertion.

  • You can add or modify amplitudes from the plot window:

    • To add new amplitudes, right-click the plot, and select Edit. Click Insert to add a new row to the Edit Bound dialog box. Specify the start and end amplitudes of the new bound segment in the Amplitude column. Specify the corresponding start and end times in the Time column.

    • To modify the start and end amplitudes, drag the bound segment. Alternatively, right-click the segment, and select Edit. Specify the new amplitudes in the Amplitude column.

    You must click Update Block before simulating the model.

Command-Line Information

Parameter: LowerBoundAmplitudes
Type: string
Value: [] | finite numbers | matrix of finite numbers | cell array of matrices with finite numbers. Must be specified inside single quotes ('').
Default: []

Enable zero-crossing detection

Ensure that the software simulates the model to produce output at the bound edges. Simulating the model at the bound edges prevents the simulation solver from missing a bound edge without asserting that the signal satisfies that bound.

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

Settings

Default: On

On

Simulate model at the bound edges

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

Off

Do not simulate model at the bound edges. The software may not compute the output at the bound edges.

Command-Line Information

Parameter: ZeroCross
Type: string
Value: 'on' | 'off'
Default: 'on'

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

This parameter has no effect if you do not specify any bounds.

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

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

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: string
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

Default: []

A MATLAB expression.

Dependencies

Enable assertion enables this parameter.

Command-Line Information

Parameter: callback
Type: string
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 a Simulink model window, the Simulation Diagnostics window opens to display an error message. 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 and produce 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: string
Value: 'on' | 'off'
Default: 'off'

Output assertion signal

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

  • True (1) if assertion succeeds, i.e., all bounds are satisfied

  • False (0) if assertion fails, i.e., a bound is violated.

The output signal data type is Boolean only if the Implement logic signals as Boolean data option in the Optimization pane of the Configuration Parameters dialog box of the Simulink model 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: string
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 double-clicking the block.

Command-Line Information

Parameter: LaunchViewOnOpen
Type: string
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, 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 or selecting Simulation > Start. This action also linearizes the portion of the model between the specified linearization input and output.

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

A new option Response Optimization appears under Tools of Simulink Control Design Model Verification blocks if Simulink Design Optimization™ is installed.

Response Optimization

Open the Design Optimization tool to optimize the model response to meet design requirements specified in the Bounds tab.

This button appears in Simulink Control Design Model Verification Block Parameters dialog box only if you have Simulink Design Optimization software.

See Also

Was this topic helpful?