A good view of other road users is crucial for safe driving. A-pillars or B-pillars that are too thick can restrict a driver’s field of vision and quickly lead to danger.
Now, virtual reality specialists at DaimlerChrysler Research have developed a visualization process that enables developers to realistically assess how vehicle design affects a driver’s field of vision - before a new model even exists.
Maybe it’s a good thing that Bettina Westerburg and Ralf Specht didn’t opt for careers in an automobile showroom. When asked about the availability of one vehicle, the DaimlerChrysler researchers reply that there are no plans to build it in its present design.
As for the other model - a strikingly beautiful roadster that the visitor can hardly wait to put through its paces - they can only shrug apologetically and explain that the car won’t be hitting the market for another three years.
In fact, the two specialists in virtual and mixed reality readily admit that a drivable prototype hasn’t even been built yet. At this point there are only design models. And a sidelong glance is enough to reveal the mockup nature of the test drive. The elegant roadster’s smooth curves - and the cockpit - come to an abrupt end right behind the wing mirror.
In reality, the visitor has arrived in the CAVE, a high-tech video cube-like structure that offers visitors a unique “driving” experience. There’s only one rule here: Don’t believe your own eyes. That’s because the five surfaces of the CAVE are projection screens that display 3D images of an extensive array of virtual road scenes.
For example, you might feel as if you are actually steering a flawless arc through a left-hand bend on a serpentine road. And were it not for the autumn leaves on the shoulder of the road - and the fact that a tiny part of your brain still remembers it’s springtime outdoors - it would be impossible to tell that the scene is only a simulation. And that’s exactly the point: Everything seems so real. The instrument panel with its cluster of dials, the sun visors, the A-pillar separating the windshield from the side window - they’re all there. What’s more, there’s even the familiar film of dirt on the part of the windshield where the wipers don’t reach - and which somewhat clouds the view of the road beyond.
And that’s really the essence of this project in “video-based ergonomics.” The two engineers’ objective is to be able to investigate - under “real” conditions, and as early as possible in the development process - how vehicle design affects a driver’s field of vision. Such tests are designed to answer questions like: Is the A-pillar sufficiently slender to ensure that an important part of the road will not be hidden from view when turning left? Does one design variant restrict driver visibility more than another? And if so, in what road situations does this apply?
> Ergonomics from the start
It wouldn’t be fair to suggest that vehicle developers have only just begun to pose such questions. Ergonomics has long been playing a very important role in vehicle development, with voluntary test persons asked to assess factors like the operability of switches and controls, the feeling of space within a car - and also driver visibility ahead, sideways and to the rear. Yet there is one major shortcoming with such an approach. “You’ve got to have real prototypes,” explains Bettina Westerburg. “But the prototypes aren’t even built until a relatively late stage in the development process. If it turns out that there are in fact problems with driver visibility, it’s usually too late to change the design. And if such changes are unavoidable, the needed modifications are very costly.”
In an effort to resolve this dilemma, the virtual reality (VR) specialist and her colleague Ralf Specht were commissioned by the Development department at the Vans business unit to develop a method for evaluating driver visibility at an earlier stage in the development process.
Their solution? Given that the position, width, shape, slope and height of the A-pillar are all determined long before the first prototype is built, it’s possible to use VR technology in a CAVE to recreate these aspects of vehicle geometry in a highly realistic simulation. The only other ingredient that’s needed is the outside world - in other words, the type of real driving situations in which it is crucial for drivers to have excellent visibility ahead and to the sides.
The road scenes for this simulation were filmed with a camera that would make even Hollywood specialists green with envy: a videocam with six lenses to provide an all-round, 360-degree view.
The camera was mounted on the roof of a Mercedes-Benz CLK coupe, directly above the driver’s seat. This position, as the Ulm-based researchers discovered, is identical to the line of sight of a driver behind the wheel of a Mercedes-Benz Vito van — the study vehicle used for the pilot project. The CLK also had another essential characteristic: Its wheelbase is almost exactly the same length as that of the Vito. The filmed sequences thus show the vehicle surroundings precisely as they would appear to the driver of a real Vito.
> Squaring the circle
Yet before the film could have its “premiere” in the CAVE at the Sindelfingen VR Center, the research team had one more very tricky task to solve. It was, in fact, the equivalent of squaring the circle - or, to be more precise, converting a sphere into a cube. This is because the CAVE is equipped with up to five flat, separately controllable projection surfaces. The 360-degree camera, on the other hand, produces a panoramic “curved” image.
“Projecting the images onto planar surfaces was a very complex task,” explains Specht. This is because objects that extend over two or even three of the cube’s different projection surfaces - for example large houses at the side of the road - have to be shown in exactly the right perspective. In the meantime, however, developers at the Vans business unit have access to a video library featuring about ten highly realistic 3D film sequences lasting up to several minutes in length.
> “Casting” for the roadster
Just like in Hollywood, achieving success with one project - Specht and Westerburg have won kudos including an innovation award from the Vans business unit - is the best means of securing funding for a follow-up. At present, the two researchers are producing video sequences for the Mercedes Car Group, which developers will be using to study driver visibility in two future roadsters.
In this case, the “casting” process for the role of a suitable camera dolly was not quite as simple. Neither a sedan nor a coupe are low enough to recreate the line of sight from a roadster, and a go-kart is not an option due to its short wheelbase.
With a big grin, Ralf Specht gestures to the room next door, where a low-slung sports car hugs the floor: A Lotus Super Seven will have the honor of providing the optimal line of sight for the future Mercedes-Benz roadsters.
> The struggle to design the best A-pillar
The design of an element such as the A-pillar offers a perfect illustration of how important it is in vehicle development to reconcile different and often competing requirements. Of all the many individuals involved in the development of a new model, each has his or her own “agendas” when it comes to this seemingly simple component.
Design and safety
For reasons of styling, a designer will often favor a gently sloping A-pillar that is as slender as possible. The engineer, by contrast, who needs to run increasing amounts of wiring through the vehicle interior, will prefer a much thicker design — as will the specialist in passive safety, who perhaps wants to conceal an airbag within the steel element.
Lightweight engineering and production technology
Researchers charged with exploiting the principles of lightweight engineering in order to reduce the amount of material used, and therefore vehicle weight, are also likely to opt for a less bulky design. But this can give rise to opposition on the part of production engineers, who are responsible for controlling the costs of making the tools and manufacturing the workpiece. By the same token, production planners need to verify that the welding robot will be able to reach all the welding sites, while the service specialist has to ensure that the windshield can be easily replaced if necessary.
Good visibility for large and small
The ergonomists are chiefly concerned with ensuring that this element of vehicle architecture doesn’t hinder a driver’s visibility. With the help of standardized video technology, visibility can now be studied in identical driving situations. What’s more, using still frames, for example, researchers can directly compare how different design variants will affect visibility.
This method also dramatically emphasizes how a person’s height affects his or her field of vision from within a vehicle. By means of a computer-generated change in perspective, it is possible to show an average-sized person the view that people with particularly large or small builds would have through the windshield and side window.
Visibility as a Euro NCAP standard
In the future, such studies of drivers’ fields of vision will become increasingly important. For example, plans exist to include field of vision as one of the criteria for assessing the safety of new vehicle models on the basis of the Euro NCAP standard.