Real or rendered? Honda conducts virtual crash tests

SAN JOSE -- Crash-testing cars is an incredibly important part of vehicle development, but also very costly. Eric DeHoff, technical leader for Honda's crash safety program in the US, showed how the company is using computer simulation to conduct extensive crash testing during a seminar at Nvidia's GTC developer conference.

In truth, most automakers rely on virtual crash testing, running computer-constructed models of cars through scenarios that replicate real-world physics. This testing shows engineers areas of a car's safety cage that may need to be bolstered, or other components that might intrude into the cabin and injure passengers.

DeHoff's twist on virtual crash testing involved giving the vehicle models a photorealistic rendering. The CAD models commonly used in crash testing, and that Honda has used previously, show an approximation of the car, a slightly crude graphical rendering. The rendering accurately reflects the safety cage engineering, but will make sense only to a trained safety engineer.

Using a photorealistic model, DeHoff showed how a virtual crash test can look exactly like a real crash test. Even more useful, at any point in the simulation, he can strip away elements of the model, such as removing the sheet metal skin to see what is going on with the sub-frame.

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In his presentation, DeHoff admitted that one of the big advantages of using photorealistic modeling was to convince non-expert executives within the company in how well virtual crash testing works.

Referring to standard NHTSA crash tests, DeHoff said that Honda's virtual roof crash tests are extremely accurate when compared to real-world tests. For the more recent small overlap test, DeHoff said the virtual testing was the least accurate due to only a year's worth of historical data. However, in his world "least accurate" means that the difference in metal deformation between virtual and real varied up to 15 mm.

Virtual crash testing improves safety because automakers can run many more tests than they can with actual models. Where Honda's computers can render and run a virtual test in 12 hours, according to DeHoff, real-world model testing requires days to build each model. These real models are also very expensive, ranging from $200,000 to $1 million each.

Along with the tests required by NHTSA, DeHoff said that Honda's own requirements go 20 to 25 percent above the government's. He also pointed out that the virtual tests let him vary the tests, moving the position or angle of an obstacle to gather safety data that would not be revealed by the standard tests.

Real models aren't out of the picture entirely. DeHoff said that Honda builds them and crashes them, verifying what he sees in his virtual tests.