Types of HIL

Within HIL simulation and testing there is a vast range of applications and test requirements that can be covered. The design process of a HIL solution involves careful analysis of both applications and requirements to guarantee the needed test coverage.

The level of HIL reconfigurability can also have a significant impact on the design of the system. If repurposing of system I/Os capabilities is available by software, the total number of pins can be largely reduced with an immediate effect on the cost of the system. See “Why NI for HIL?” section to learn more about most efficient ways of translating test case requirements into I/O needs.

A first possible approach to classification of HIL systems in the automotive space is represented by the testing focus: hardware validation or software validation.

In hardware validation, typical tests include electrical connectivity, performance/characterization tests, or smoke tests.

In software validation, typical tests include functional validation. The advent of SDV is dramatically increasing the demand and scale for software testing. SDV software typically sits on larger ECUs (HCP/Zonal) hosting a variety of software applications. Each software application could interact with several domains of the vehicle and the external environment to execute on the assigned control tasks; as an example, active safety algorithms could be leveraging the combined actuation of chassis and powertrain vehicle capabilities based on environmental conditions. The needs of the ECU under test for interaction with several domains is fulfilled by scaling accordingly the extent of the vehicle simulation provided by the HIL system.

Therefore, depending on the testing needs of the ECU under test HIL test systems can range from desktop HIL applications employed to test individual components such as lighting modules or body control systems to large system integration HILs, which include real/virtual multi-ecu systems to complete vehicle architectures used for integration testing.