Test harnesses provide a development and testing environment that leaves the main model design intact. You can test a functional unit of your model in isolation without altering the main model. This example demonstrates refining and testing a controller subsystem using a test harness. The main model is a controller-plant model of an air conditioning/heat pump unit. The controller must operate according to several simple requirements.
Access the model. Enter
Copy this model file and supporting files to a writable location on the MATLAB® path:
sltestHeatpumpExample.slx sltestHeatpumpBusPostLoadFcn.mat PumpDirection.m
Open the model.
In the example model:
The controller accepts the room temperature and the set temperature inputs.
The controller output is a bus with signals controlling the fan, heat pump, and the direction of the heat pump (heat or cool).
The plant accepts the control bus. The heat pump and
the fan signals are Boolean, and the heat pump direction is specified
+1 for cooling and
The test covers four temperature conditions. Each condition corresponds to one operating state with fan, pump, and pump direction signal outputs.
|Temperature condition||System state||Fan command||Pump command||Pump direction|
and select Test Harness > Create for ‘Controller’.
Set the harness properties:
In the Basic Properties tab:
Clear Save test harness externally
Sources and Sinks: None and Scope
Clear Add separate assessment block
Select Open harness after creation
Click OK to create the test harness.
In the test harness, double-click
open the subsystem.
Connect the chart to the Inport blocks.
In the test harness, click the Save button to save the test harness and model.
Navigate to the top level of
Create a test input for the harness with a constant
Troom. Connect a Constant block
Tset input and set the value to
Add a Sine Wave block to the harness
model to simulate a temperature signal. Connect the Sine Wave block
to the conversion subsystem input
Double-click the Sine Wave block and set the parameters:
Phase (rad): 0
Select Interpret vector parameters as 1–D.
Connect Inport blocks to the Data Store Write inputs.
In the Configuration Parameters dialog box, in the Data
Import/Export pane, select Input and
u is an existing structure
in the MATLAB base workspace.
In the Solver pane, set Stop
Open the scope in the test harness and change the layout to show three plots.
Click Run to simulate.
Observe the controller output.
the IDLE condition where
|Troom - Tset| < DeltaT_fan.
This is a bug.
fan_cmd should equal
fan_cmd control output must be changed for
In the harness model, open the
set to return
IDLE is now:
IDLE entry: fan_cmd = 0; pump_cmd = 0; pump_dir = 0;
Simulate the harness model again and observe the outputs.
fan_cmd now meets the requirement