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Check that model signal satisfies step response bounds during simulation

Simulink Design Optimization

Check that a signal satisfies step response 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 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 return 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 Step Response Characteristics 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 the Bode magnitude, and
optimize the model response to satisfy both time-domain 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.

Task | Parameters |
---|---|

Specify step response bounds to: Assert that a signal satisfies the bounds Optimize model response so that a signal satisfies the bounds
| Include
step response bound in assertion in Bounds tab. |

Specify assertion options (only when you specify step response bounds). |
In the |

Open Response Optimizer to optimize model response | Click Response
Optimization |

Plot step response | Click Show
Plot. |

Display plot window instead of Block Parameters dialog box on double-clicking the block. | Show
plot on block open |

Check that the step response satisfies *all* the
characteristics specified in:

The software displays a warning if the signal violates the specified step response characteristics.

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

The bounds also appear on the step response plot if you click **Show Plot**,
as shown in the next figure.

By default, the line segments represent the following step response requirements:

Amplitude less than or equal to –0.01 up to the rise time of 5 seconds for 1% undershoot

Amplitude between 0.9 and 1.2 up to the settling time of 15 seconds

Amplitude equal to 1.2 for 20% overshoot up to the settling time of 15 seconds

Amplitude between 0.99 and 1.01 beyond the settling time for 2% settling

If you clear **Enable assertion**, the bounds
are not used for assertion but continue to appear on the plot.

**Default:** On

- On
Check that the step response satisfies the specified bounds during simulation.

- Off
Do not check that the step response satisfies the specified bounds during simulation.

Clearing this parameter disables the step response 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**.

Parameter: `EnableStepResponseBound` |

Type: character vector |

Value: `'on'` | `'off'` |

Default: `'on'` |

Time, in seconds, when the step response starts.

**Default:** 0

**Minimum:** 0

Finite real nonnegative scalar.

To assert that step time value is satisfied, select both

**Include step response bound in assertion**and**Enable assertion**.To modify the step time value from the plot window, drag the corresponding bound segment. Alternatively, right-click the segment, and select

**Edit**. Specify the new value in**Step time**. You must click**Update Block**before simulating the model.

Parameter: `StepTime` |

Type: character vector |

Value: `0` | ```
finite
real nonnegative scalar
``` . Must be specified inside single
quotes (`''` ). |

Default: `0` |

Value of the signal level before the step response starts.

**Default:** 0

Finite real scalar not equal to the final value.

To assert that initial value is satisfied, select both

**Include step response bound in assertion**and**Enable assertion**.To modify the initial value from the plot window, drag the corresponding bound segment. Alternatively, right-click the segment, and select

**Edit**. Specify the new value in**Initial value**. You must click**Update Block**before simulating the model.

Parameter: `InitialValue` |

Type: character vector |

Value: `0` | ```
finite
real scalar not equal to final value
``` . Must be specified
inside single quotes (`''` ). |

Default: `0` |

Final value of the step response.

**Default:** 1

Finite real scalar not equal to the initial value.

To assert that final value is satisfied, select both

**Include step response bound in assertion**and**Enable assertion**.To modify the final value from the plot window, drag the corresponding bound segment. Alternatively, right-click the segment, and select

**Edit**. Specify the new value in**Final value**. You must click**Update Block**before simulating the model.

Parameter: `FinalValue` |

Type: character vector |

Value: `1` | ```
finite
real scalar not equal to the initial value
``` . Must be specified
inside single quotes (`''` ). |

Default: `1` |

Time taken, in seconds, for the signal to reach a percentage
of the final value specified in **%
Rise**.

To assert that rise time value is satisfied, select both

**Include step response bound in assertion**and**Enable assertion**.To modify the rise time from the plot window, drag the corresponding bound segment. Alternatively, right-click the segment, and select

**Edit**. Specify the new value in**Rise time**. You must click**Update Block**before simulating the model.

Parameter: `RiseTime` |

Type: character vector |

Value: `5` | ```
finite
positive real scalar
``` . Must be specified inside single quotes
(`''` ). |

Default: `5` |

The percentage of final value used with the **Rise time** to
define the overall rise time characteristics.

To assert that percent rise value is satisfied, select both

**Include step response bound in assertion**and**Enable assertion**.To modify the percent rise from the plot window, drag the corresponding bound segment. Alternatively, right-click the segment, and select

**Edit**. Specify the new value in**% Rise**. You must click**Update Block**before simulating the model.

Parameter: `PercentRise` |

Type: character vector |

Value: `80` | ```
positive
scalar less than (100 – % settling)
``` . Must be specified
inside single quotes (`''` ). |

Default: `80` |

The time, in seconds, taken for the signal to settle within
a specified range around the final value. This settling range is defined
as the final value plus or minus the percentage of the final value,
specified in **%
Settling**.

To assert that final value is satisfied, select both

**Include step response bound in assertion**and**Enable assertion**.To modify the settling time from the plot window, drag the corresponding bound segment. Alternatively, right-click the segment, and select

**Edit**. Specify the new value in**Settling time**. You must click**Update Block**before simulating the model.

Parameter: `SettlingTime` |

Type: character vector |

Value: `7` | ```
positive
finite real scalar greater than rise time
``` . Must be specified
inside single quotes (`''` ). |

Default: `7` |

The percentage of the final value that defines the settling
range of the **Settling
time** characteristic.

**Default:** 1

**Minimum:** 0

**Maximum:** 100

Real positive finite scalar, less than (100 – % rise) and less than % overshoot.

To assert that percent settling value is satisfied, select both

**Include step response bound in assertion**and**Enable assertion**.To modify the percent settling from the plot window, drag the corresponding bound segment. Alternatively, right-click the segment, and select

**Edit**. Specify the new value in**% Settling**. You must click**Update Block**before simulating the model.

Parameter: `PercentSettling` |

Type: character vector |

Value: `1` | ```
Real
positive finite scalar less than (100 – % rise) and less than
% overshoot
``` . Must be specified inside single quotes (`''` ). |

Default: `1` |

The amount by which the signal can exceed the final value before settling, specified as a percentage.

To assert that percent overshoot value is satisfied, select both

**Include step response bound in assertion**and**Enable assertion**.To modify the percent overshoot from the plot window, drag the corresponding bound segment. Alternatively, right-click the segment, and select

**Edit**. Specify the new value in**% Overshoot**. You must click**Update Block**before simulating the model.

Parameter: `PercentOvershoot` |

Type: character vector |

Value: `10` | ```
Positive
real scalar greater than % settling
``` . Must be specified inside
single quotes (`''` ). |

Default: `10` |

The amount by which the signal can undershoot the initial value, specified as a percentage.

**Default:** 1

**Minimum:** 0

**Maximum:** 100

Positive finite real scalar.

To assert that percent undershoot value is satisfied, select both

**Include step response bound in assertion**and**Enable assertion**.To modify the percent undershoot from the plot window, drag the corresponding bound segment. Alternatively, right-click the segment, and select

**Edit**. Specify the new value in**% Undershoot**. You must click**Update Block**before simulating the model.

Parameter: `PercentUndershoot` |

Type: character vector |

Value: `1` | ```
positive
finite real scalar between 0 and 100
``` . Must be specified
inside single quotes (`''` ). |

Default: `1` |

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*.

**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.

Parameter: `ZeroCross` |

Type: character vector |

Value: `'on'` | `'off'` |

Default: `'on'` |

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:

Execute a MATLAB expression, specified in

**Simulation callback when assertion fails (optional)**.Stop the simulation and bring that block into focus, by selecting

**Stop simulation when assertion fails**.

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

**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.

This parameter enables:

**Simulation callback when assertion fails (optional)****Stop simulation when assertion fails**

Parameter: `enabled` |

Type: character vector |

Value: `'on'` | `'off'` |

Default: `'on'` |

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.

**Default:** `[]`

A MATLAB expression.

**Enable
assertion** enables this parameter.

Parameter: `callback` |

Type: character vector |

Value: `''` | ```
MATLAB
expression
``` |

Default: `''` |

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.

**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.

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.

**Enable
assertion** enables this parameter.

Parameter: `stopWhenAssertionFail` |

Type: character vector |

Value: `'on'` | `'off'` |

Default: `'off'` |

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

True (

`1`

) if assertion succeeds, i.e., all bounds are satisfiedFalse (

`0`

) if assertion fails, i.e., 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.

**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.

Use this parameter to design complex assertion logic. For an example, see Verify Model Using Simulink Control Design and Simulink Verification Blocks (Simulink Control Design).

Parameter: `export` |

Type: character vector |

Value: `'on'` | `'off'` |

Default: `'off'` |

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**.

**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.

Parameter: `LaunchViewOnOpen` |

Type: character vector |

Value: `'on'` | `'off'` |

Default: `'off'` |

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 .

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