HIL testing grows as its nature changes

Model-based design and hardware-in-the-loop testing have long been dominant in the automotive and aerospace industries, as I noted last December in “Model-based design and early verification aid designers” and last July in “High-level software for embedded-system design: doing your job?” As I noted in those articles, the techniques are expanding to other applications areas as well. I highlight one such application in “Model-based design aids medical device test” from the latest issue of Test & Measurement World. That article recounts the Cleveland FES Center’s use of MathWorks model-based design tools to reduce the development time of functional electrical stimulation, which can restore movement to individuals with neuromuscular disabilities.

But as the use of model-based design and HIL testing grow, the very nature of the techniques may be changing, reports Chris Washington, senior product manager at National Instruments. As an example, he cites an engine-control unit undergoing HIL testing. Normally, a software model would represent the rest of the vehicle and environmental variables. But if the ECU integrates sensors, then the software model cannot supply representations of the environmental variables that the ECU itself must acquire. Consequently, an effective test system must include, for example, acceleration capabilities that put the ECU through its expected ranges of roll, pitch, and yaw. Washington calls the type of testing that can provide such excitation “real-time testing.”