Sometimes when you are trying to solve a problem the model is just too big to figure out where the problem lies. You may know the subsystem where it occurs, but the problem is, how do you test that subsystem apart from the whole?
Test harnesses!
Starting around 2015, Simulink provided a methodology for doing this (e.g., creating test harnesses from an atomic unit within the full model).
- Set up the inputs and outputs to the subsystem under “test” for logging.
- Simulate the full model through one of the scenarios that causes the issue.
- Use the logged data as inputs to the test harness.
Dig deeper!
The logged data provides the baseline for your exploration; e.g., it provides a basic valid set of inputs. The objective now is to vary those inputs to determine the root cause of your error, and once that is accomplished to validate your solution. (Note: This image shows that getting to the root is to keep the “tree” alive)
Save the test
A pass/fail criteria should be defined for the test harness. While the test harness may have been created as part of a debugging exercise, it should be saved as part of the regression testing suite.