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Pre-Safe: Benz Preps For Crashes


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2003 Mercedes-Benz S-Class (9/15/2002)

forumBlink and you’re likely not even to notice. The big Mercedes-Benz S-Class charges into the corner far too fast. In desperation, the driver yanks the steering wheel, but all that does is send the sedan skidding out of control.

Luckily, it has all taken place on a test track. If it had happened on the highway, odds are that the car would now be little more than a badly damaged heap. But a recent demonstration showed TheCarConnection.com that the German automaker’s new Pre-Safe system is an entirely new approach to the concept of automotive safety.

As the driver regains control, the whir of electric motors fills the passenger compartment. That’s when you realize what has happened. The noise is the sound of electric seatbelt pretensioners loosening up. When the Pre-Safe computer determined an accident was imminent, it quickly tightened up all the seatbelts. It also moved the front passenger seat into the safest, upright position. And it closed the sunroof and any open windows to reduce the odds of a passenger ejection, one of the most deadly things that can happen in a crash.

“In 60 percent of real-world accidents,” notes Roland Bachmann, Mercedes’ senior manager of safety, “you have a very long time, anywhere from 250 milliseconds to five seconds” between the point when a vehicle loses control and the collision actually occurs.

For a motorist spinning out of control, it might seem like an instance, but when it comes to the world of microprocessors, that’s more than enough time for Pre-Safe to take a series of steps to prepare the vehicle and its occupants for the likelihood of a crash.

Intelligent response

In current form, Pre-Safe draws its cues from the vehicle’s Brake Assist system and Electronically Stability Program. Both of these are actually designed to prevent accidents; Brake Assist actually increases brake pressure if it senses a panic stop where the driver isn’t pressing the brake pedal hard enough, while ESP uses various methods to try to prevent a skid.

But “whenever the car goes beyond the point where it is stable,” says Bachmann, “we want to have the Pre-Safe system activate.”

Stability is a relative term, of course, and the system has to be carefully programmed so it does not activate too early—or too frequently. Indeed, if a performance-minded driver turns off ESP—which would then allow the car to slip a bit when cornering aggressively—the Pre-Safe activation point is set to a higher threshold. In other words, says Bachmann, “If you want to push the limits of the vehicle’s handling, we’ll give you more leeway.”

The Pre-Safe system makes its debut on the 2003 update of Mercedes’ top-line S-Class, but according to spokesman Fred Heiler, “every year we’ll expand its availability to more and more models and add more and more features.”

What’s in the works? One of the most immediate goals is to develop technology that can sense what’s going on outside the vehicle, notes Bachmann. In current form, Pre-Safe cannot detect a wide variety of common accidents — another car running a red light, for example, and slamming into the side of your vehicle.

“For this,” Bachmann adds, “we need radar sensors to see what is going on around you.”

Some Mercedes products already come with onboard radar as part of a system Mercedes calls Distronic. Generically known as active cruise control, it lets the driver set a preferred speed, but then adjusts the vehicle’s actual speed automatically depending on the traffic flow. Distronic, Bachmann says, “is not precise enough,” so an even more sophisticated radar system is under development.

Ultimately, Pre-Safe could detect and respond to virtually all types of accidents ahead of time and interact with all current and future safety systems. It might be used to trigger earlier inflation of a vehicle’s airbags, for one thing. Some all-new approaches might also be possible, Bachmann suggests, such as bumpers that could be extended several inches to better absorb the forces of an impact.

Mercedes is by no means the only automaker looking at ways to predict and respond to an accident ahead of time. Ford is equipping many of its SUVs with headliner-mounted airbags designed to deploy if a rollover appears likely.

And computer-aided technology is offering a wide range of ways to help prevent accidents in the first place. Volvo recently demonstrated a safety concept vehicle that can warn drivers when they accidentally drift out of their lane, and the car keeps an electronic eye focused on the blind spots not covered by its sideview mirrors.

The first step is to prevent as many accidents as possible, but when a crash is unavoidable, the goal is to reduce the likelihood of death and injuries.

 
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