What is Hardware in the Loop (HIL) and Software in the Loop (SIL) Testing?

By Gabriel Staples
Written: 6 June 2018
Last Updated: 7 June 2018

Quadcopter navigation algorithm SIL test (live video).

In mechatronics and control theory, testing is an important part of controller validation. You need to run experiments to prove that your software/analog/digital controller, actuator, algorithm, etc, does what it’s supposed to do. Experiments, however, can be expensive, time-consuming, difficult,
dangerous, or even impossible to test under all conditions. Therefore, you can do Hardware in the Loop (HIL) testing and Software in the Loop (SIL) testing/simulation to aid the testing, verification and validation of your controller without having to resort to pure, fully-physical testing with actual products under actual conditions.