Traditionally, engineers have conducted vehicle tests using finished cars on test courses or public roads to check the vehicle’s performance and safety response.
However, NI explains that certain limitations, such as weather and fluctuating road surface conditions, can make it difficult to conduct reproducible tests on roads in a timely manner. EV are also extremely complex due to their many subsystems, which are all interdependent on each other, making the job challenging for automotive test engineers with short development cycles and pressure to limit costs.
To combat this, Subaru replaced the roads in the validation tests with an NI HIL simulation solution built on NI PXI products and LabVIEW software. This NI claims, enabled Subaru to eliminate environmental factors and ‘thoroughly and efficiently’ test a vehicle’s embedded controller in a virtual environment before running real-world diagnostics on the complete system.
Subaru explains that by using NI PXI products and LabVIEW, it was able to implement a customised HIL system in a matter of weeks and develop the software in-house. This apparently kept purchasing costs to around ‘one-third of the cost of adopting solutions from other companies’ and software development costs to approximately one-sixth of the cost of commissioning an outside developer’.
Subaru outfitted its vehicle test solution with a controller-driven dynamometer by HORIBA and CarSim vehicle dynamics simulation software deployed by Virtual Mechanics, to create load conditions equivalent to those on actual roads.
NI says that the driving system transmits the calculated values to the NI HIL system in real time to create closed-loop control between the models on the HIL system and the driving system. As a result, NI claims the HIL interaction system can apply the appropriate load to the vehicle throughout the tests.
Subaru plans to use this test system at the final stages of development for EV as a final quality check, and eventually expand its use for all car types. By adopting this system, Subaru anticipates reducing labor hours by half compared to conventional methods.