Simulink.op.ModelOperatingPoint
Complete information that represents model operating point in simulation
Description
A Simulink.op.ModelOperatingPoint object contains a complete
representation of a model operating point that you can use to specify the initial state for a
simulation. For example, when you run a set of simulations for a model of a system that has a
startup phase or initialization behavior, you can simulate the model through the end of the
startup or initialization phase once, save the model operating point, then run a set of
simulations that use the operating point as the initial state. If you do not modify the model,
simulating a model using a Simulink.op.ModelOperatingPoint object as the
initial state produces the same results as a simulation with no initial state
specified.
The operating point for a model represents the model state in simulation, including logged block states, hidden block states, the state of the solver and execution engine, and output values for some blocks. For more information, see Speed Up Simulation Workflows by Using Model Operating Points.
Creation
A model configured to save the final operating point creates a
Simulink.op.ModelOperatingPoint object when the simulation completes or
when you pause or stop the simulation. To configure a model to save the final operating point:
On the Modeling tab, click Model Settings.
In the Configuration Parameters dialog box, select Data Import/Export.
Select Final states and Save final operating point.
By default, the Simulink.op.ModelOperatingPoint object is saved using a
variable called xFinal. To save the operating point using a different
variable name, specify the variable name you want to use in the Final
states text box.
When you return simulation results using a single simulation output, the
Simulink.op.ModelOperatingPoint object is returned as part of the Simulink.SimulationOutput object that contains all the simulation data.
Properties
Object Functions
Examples
Open the model vdp.
mdl = "vdp";
open_system(mdl);Configure the model to save the final operating point at the end of simulation.
On the Modeling tab, under Setup, click Model Settings.
In the Configuration Parameters dialog box, select the Data Import/Export pane.
On the Data Import/Export tab, select Final states and Save final operating point.
Click OK.
Alternatively, create a Simulink.SimulationInput object to store the parameter values for the simulation. Then, use the setModelParameter function to specify the parameter values to use in the simulation.
simIn = Simulink.SimulationInput(mdl); simIn = setModelParameter(simIn,"SaveFinalState","on"); simIn = setModelParameter(simIn,"SaveOperatingPoint","on");
Set the stop time for the simulation to 10 seconds. On the Simulation tab, under Simulate, in the Stop Time box, enter 10, or use the setModelParameter function to specify the value of the StopTime parameter for the simulation.
simIn = setModelParameter(simIn,"StopTime","10");
Simulate the model.
out = sim(simIn);
To view the simulation results, double-click the Scope block in the model. The plot in the Scope displays the values of the signals x1 and x2 over the 10-second simulation.
Resume the simulation by using the operating point you saved at the end of the first simulation as the initial operating point for the second simulation.
Get the final operating point from the first simulation from the Simulink.SimulationOutput object out.
vdpOP = out.xFinal;
Specify the operating point as the initial state for the simulation.
On the Modeling tab, under Setup, click Model Settings.
In the Configuration Parameters dialog box, on the Data Import/Export pane, select Initial state.
In the text box, enter
vdpOP.Click OK.
Alternatively, create another Simulink.SimulationInput object to configure this simulation. Then, use the setInitialState function to specify the initial state.
simIn2 = Simulink.SimulationInput(mdl); simIn2 = setInitialState(simIn2,vdpOP);
Set the stop time for this simulation to 20. On the Simulation tab, under Simulate, in the Stop Time box, enter 20, or use the setModelParameter function to specify the value of the StopTime parameter for the simulation.
simIn2 = setModelParameter(simIn2,"StopTime","20");
Simulate the model again, resuming the prior simulation by starting this simulation from the final operating point saved in the first simulation.
out2 = sim(simIn2);
The plot in the Scope window updates to show the data from this simulation. The time axis starts at 0 and goes to the simulation stop time of 20. Because this simulation started from the initial operating point from the first simulation, which ended after 10 simulation seconds, the plot shows the values of the signals x1 and x2 only between simulation time 10 seconds and 20 seconds.
Tips
When you load an operating point as the initial state for a simulation, the software disables the Block reduction parameter for the model. For best results, clear the Block reduction parameter before running a simulation in which you save a model operating point. If the Block reduction parameter was enabled when the operating point object was saved, you might not be able to load the operating point.
When you use a model operating point as the initial state for a simulation that uses a fixed-step solver with the Fixed-step size (fundamental sample time) parameter set to
auto, the software uses the fixed step size saved in the model operating point object.When you use a model operating point as the initial state for a simulation that uses a variable-step solver with the Max step size parameter set to
auto, the software uses the maximum step size saved in the model operating point object.
