Let's do an introduction to Hardware in the loop testing
or HIL testing in short.
I will cover both, the set up of HIL systems
as well as best practices for controller HIL testing.
Let's look at a HIL test setup.
There are typically two main components.
First, your controller and the test.
This includes both, the production hardware
and the embedded software that requires thorough testing.
And second, the HIL test system.
The HIL system is composed of a real-time simulator, that
runs a digital twin deterministically, together
with I/O modules, that ensure low latency data
acquisition, signal conditioning and communication
with the controller under test.
The host computer runs a dedicated application software,
that supports you on the setup and operation
of the real-time simulator.
Depending on the size of your group
and how you organize development of embedded software,
the hill system set up and controller HIL testing,
can be done by the same or different teams.
Let's assume our embedded system group is segmented into three.
Simon's team, focusing on assembling and setting up
new HIL test systems.
Sophie's team, in charge of running embedded software
test campaigns and Corine's team,
who is tasked to develop and revise the embedded software.
So, the question is, how are we enabling these teams to succeed
in their specific task.
Simon, has previously built a HIL test system,
based on the speed goat performance machine.
Simon's team, is now challenged to specify
a new, much more complex field test
system, which is required to integrate high power actuators
and electronic loads and sources.
Implementing such a HIL system is time-consuming and requires
specific expertise.
With that in mind, Simon has decided to rely on speed
goat's know how, to provide him with a modular wreck
mounted HIL solution, customized to his needs.
The final solution looked as follows.
Two wreck mounted performance real time machines,
enabling distributed and synchronized simulation across
multiple schatz's.
This setup fully integrates all power electronics components,
the required signal routing and conditioning modules,
as well as breaker panels in the cabling harness.
For Simon's team, this is a true plug and play solution.
With hardware hurdles off the table,
the team was able to focus on the design of the digital twin
and even introduce some innovations.
For instance, model parameters are now automatically
fine-tuned to fit measured data.
Connectivity with the controller was also done very quickly
with a simple drag and drop of speed goat driver blocks.
Using Simulink real time, the model
ran on the speedgoat machine with a simple click
and the team could verify correctness
of all interfaces right from Simulink.
The HIL system was instrumented with Matlab built in Designer.
User interface controls, directly
connect with real time application,
allowing the HIL system to be operated independent
from Simulink.
In parallel, Sophie's team has been creating scripts
to bench and optimize test workflows.
Part of the team has been using Simulink test,
which is shown to be a great asset worth of its investment.
For instance, most of the desktop simulation tests,
were reused in the real time runs.
Real time test campaigns were triggered
with just a few clicks and the assertion of results
was fast and easy, using inbuilt visualization tools.
Besides, detailed test reports could
be generated automatically.
This greatly simplified communication
with Corine's team and helped further
expediting software revision work.
All in all, the group was able to quickly resolve
several critical errors and run all test campaigns
without damaging any hardware.
By using the right tools, the team
could shield itself from many test trivialities
and focus on what was truly their mission, which is develop
outstanding controls.