Glossary · Engineering, integration and validation
Hardware-in-the-loop (HIL)
Also known as: HIL testing, HIL simulation
German: Hardware-in-the-Loop (HIL)
In control engineering, hardware-in-the-loop (HIL) is a test method in which the real control hardware, running its real software, is connected to a real-time simulation of the machine or process. The simulation supplies sensor signals and reacts to the controller's outputs.
- Validation
In one sentence
Hardware-in-the-loop (HIL) tests real control hardware and software against a real-time simulation of the machine or process.
Example
The drive controller of a lift is tested in a HIL setup where a real-time model simulates the car, rope and counterweight, including fault cases.
How it applies
- Engineering: HIL allows controllers to be tested before the machine exists and to test situations that are dangerous or expensive to create on real equipment.
- Testing: Fault injection in the simulation, such as sensor failures or broken wires, checks the controller's reaction reproducibly. Tests can be automated and repeated after each software change.
- Commissioning: HIL tests reduce on-site commissioning time, especially when used as part of Virtual commissioning.
- Documentation: The documentation team records the simulation model, its version and its limits alongside test results, because the evidence only holds within the model's validity.
HIL vs. SIL
In Software-in-the-loop (SIL) testing, the control software runs on a PC or virtual controller; in HIL testing, it runs on the real target hardware, so timing and I/O behavior are closer to reality. Neither replaces tests on the real machine, particularly for safety functions.