Using Operating Point Data for Model Initialization
Using Operating Points to Initialize Model Variables
Block-level variable initialization lets you specify the priority and target for individual block variables. You can also initialize variables for a whole model from the saved operating point data.
You can use
OperatingPoint objects to save sets of data necessary to
initialize a model, manipulate this data, and then use it to initialize another model, or the
same model before another simulation run. These sets of data contain a hierarchy of variable
initialization targets. Each target consists of a variable value, unit, and initialization
priority, as described in Variable Initialization Priority.
OperatingPoint data hierarchy is a tree, with nodes corresponding to
subsystems and blocks in a model. At the lowest level of the data tree, inside the block nodes,
are the variable initialization targets for that block.
When you use an
OperatingPoint to initialize a model, the solver matches
OperatingPoint data hierarchy to the model hierarchy and applies the
initialization targets from the operating point to the respective model variables. If there is
no variable matching an operating point target, this target is ignored. After applying all the
data from the operating point, the solver performs model initialization as described in Initial Conditions Computation.
After you initialize the variables and prior to simulating the model, you can open the Variable Viewer to see which of the variable targets have been satisfied. For details, see Variable Viewer.
OperatingPointobject by extracting data from the model or from the simulation log. For more information, see Extracting Variable Initialization Data into an Operating Point.
Modify the operating point data, if needed, by changing, adding, or removing targets and nodes. For more information, see Manipulating Operating Point Data.
When satisfied with the operating point data, apply it to initialize another model, or the same model for another simulation run. For more information, see Applying Operating Point Data to Initialize Model.
Extracting Variable Initialization Data into an Operating Point
You can create an
OperatingPoint object by extracting data from an
existing model or from logged simulation data. For more information, see
You can extract variable initialization targets from a model in these ways:
Start values — Initialize the model and use the variable targets corresponding to the
Startvalues in the Variable Viewer.
Prestart values — Update the model and use the variable targets corresponding to the
Prestartvalues in the Variable Viewer.
Cached data — Extract cached values of variable targets from a model that has been previously initialized or simulated. You can specify
Prestartvalues. This method lets you save time by avoiding repeated initialization of the model if the data that you want to extract has not changed.
Alternatively, you can simulate the model while logging simulation data, and then extract
variable targets from the simulation log at a specified time,
If the set of times recorded in the simulation data log contains an exact match for time
t, then the
simscape.op.createfunction extracts these variable target values into the operating point data.
If there is no exact match, but
tis between the minimum and maximum times in the simulation data log, then the function uses linear interpolation to determine the target values.
tis less than the minimum time, then the function extracts the first value for each variable in the simulation data log.
tis greater than the maximum time, then the function extracts the last value for each variable in the simulation data log.
When you extract data from a model into an operating point, the elements in the data
hierarchy of the
OperatingPoint object match the structure of the model. The
operating point data tree has nodes corresponding to subsystems and blocks in the model, with
variable initialization targets for each block at the lowest level of the data tree hierarchy.
Similarly, when you extract an operating point from logged simulation data, the operating point
data tree matches the data tree of the simulation log. For an example, see Find Relative Path to Block Node in Operating Point Data Tree.
Manipulating Operating Point Data
You can create an empty
OperatingPoint object, or populate it with the
data extracted from an existing model or from logged simulation data.
Once you create an
OperatingPoint object, you can modify it in these
Add targets one-by-one. For an example, see Add Element to an Operating Point.
Copy and insert elements. For an example, see Copy Element from an Operating Point. You can then insert the copied element into another operating point using the
Remove elements. For an example, see Remove an Element from Operating Point Data.
Rename or move elements. For an example, see Rename Element to Match New Block Name.
Merge operating points. For an example, see Merge Two Operating Points.
Applying Operating Point Data to Initialize Model
To initialize a model from an operating point:
Open the Configuration Parameters dialog box.
On the Simscape pane, select the Enable operating point initialization check box.
In the Model operating point textbox, enter the name of the workspace variable associated with an
You can also use the equivalent command-line interface to set the model configuration parameters:
model_name is the name of the model and
op_name is the name of the