Schedule Execution of Multiple Controllers
A Simulink® function is a graphical object that you fill with Simulink blocks and call in the actions of states and transitions. Simulink functions are not supported in standalone Stateflow® charts in MATLAB®. For more information, see Reuse Simulink Functions in Stateflow Charts.
Goal of the Tutorial
The goal of this tutorial is to use
Simulink functions in a Stateflow chart to improve the design of a model named
sf_temporal_logic_scheduler. This model contains a Stateflow chart and three function-call subsystems. These blocks interact as
The chart broadcasts the output events
A3to trigger the function-call subsystems.
The subsystems A1, A2, and A3 execute at different rates defined by the chart.
The subsystem outputs feed directly into the chart.
No other blocks in the model access the subsystem outputs.
You can replace function-call subsystems with Simulink functions inside a chart when:
The subsystems perform calculations required by the chart.
Other blocks in the model do not need access to the subsystem outputs.
Edit a Model to Use Simulink Functions
The sections that follow describe how to replace function-call subsystem blocks in a Simulink model with Simulink functions in a Stateflow chart. This procedure reduces the number of objects in the model while retaining the same simulation results.
|1||Open the model.||Open the Model|
|2||Move the contents of the function-call subsystems into Simulink functions in the chart.||Add Simulink Functions to the Chart|
|3||Change the scope of specific chart-level
data to ||Change the Scope of Chart Data|
|4||Replace event broadcasts with function calls.||Update State Actions in the Chart|
|5||Verify that function inputs and outputs are defined.||Add Data to the Chart|
|6||Remove unused items in the model.||Remove Unused Items in the Model|
To skip the conversion steps, you can access the new model by entering:
openExample("stateflow/TemporalLogicSchedulerExample", ... supportingFile="sf_temporal_logic_scheduler_with_sl_fcns")
Open the Model
If you simulate the model, you see this result in the scope.
For more information, see Schedule Subsystems to Execute at Specific Times.
Add Simulink Functions to the Chart
Follow these steps to add Simulink functions to the Temporal Logic Scheduler chart.
In the Simulink model, right-click the A1 block in the lower right corner and select Cut from the context menu.
Open the Temporal Logic Scheduler chart.
In the chart, right-click outside any states and select Paste from the context menu.
Expand the new Simulink function so that the signature fits inside the function box.
To change the font size of a function, right-click the function box and select a new size from the Font Size menu.
Rename the Simulink function from
y = f1(u)in the function box.
Repeat steps 1 through 5 for these cases:
Copying the contents of A2 into a Simulink function named
Copying the contents of A3 into a Simulink function named
The new functions reside at the chart level because both states
SlowSchedulerrequire access to the function outputs.
Change the Scope of Chart Data
In the Model Explorer, change the scope of
Local because the
calculation for that data now occurs inside the
Update State Actions in the Chart
In the Stateflow Editor, you can replace event broadcasts in state actions with function calls.
Edit the state actions in
SlowSchedulerto call the Simulink functions
In both states, update each
duringaction as follows.
du: y = u1-y2;
Add Data to the Chart
on every state
SlowScheduler, define three
data. (For details, see Add Stateflow Data.)
Add local data
y2to the chart.
Add output data
y3to the chart.
In the model, connect the output for
y3to the scope.
To flip the Scope block, select the block. Then, in the toolstrip, on the Format tab, click Flip left-right .
Remove Unused Items in the Model
In the Model Explorer, delete output events
A3and input data
u2because the function-call subsystems no longer exist.
Delete any dashed signal lines from your model.
Run the New Model
Your new model looks something like this:
If you simulate the new model, the results match those of the original design.