- The Washington Times - Wednesday, February 18, 2004

After decades of developing air bags and seat belts and other devices to protect motorists during a crash, some automakers are now offering systems that try to protect consumers by getting them ready for the crash.

These new safety devices are generally referred to as precollision systems, although some automakers, such as Mercedes-Benz, have given them brand names, such as “Pre-Safe.”

Precollision systems are just that. They aim to prepare a car and its occupants for a crash before the crash happens. They have several goals.

One is to make sure the occupants are in the best position to benefit from, not be hurt by, the air bags because injuries can occur if the person is too close to the air bag when it deploys. Another is to keep the occupants from being thrown around in the vehicle because of slack in the seat belt.

Safety researchers have also found that one problem in a crash is that people are sometimes not sitting upright and in the proper position. They may have reclined the seat farther back than ideal, trying to catch a little nap — the passenger, that is, hopefully not the driver. Or they may be leaning against the door. If they are doing either, they may be more likely to be hurt in a crash.

In short, precollision systems try to correct such positional problems and make sure motorists get the most out of safety systems such as seat belts and air bags.

Mercedes-Benz, generally acknowledged as a leader in safety technology, was the first automaker to bring the system to consumers in its 2003 Mercedes-Benz S-Class.

Nissan has introduced a system in Japan on the luxury car that is known as the Infiniti Q45 in the United States. That means it is likely to eventually appear on U.S. models. Lexus offers it on its 2004 LS 430 and, when the new Lexus 2006 GS luxury sport sedan debuts in 2005, it will be the second Lexus model to have a precollision system.

While such systems are currently protecting well-to-do motorists, traditionally high-tech safety equipment eventually works its way into less-expensive vehicles. A good example is anti-lock brakes, once a gee-whiz item found only on the most expensive Mercedes-Benz. Now, it is standard equipment on many of the world’s most modestly priced vehicles.

While all precollision systems have the same general goal, they operate in slightly different ways. The Mercedes-Benz Pre-Safe system is triggered by emergency braking, or when the vehicle goes into a major skid that the computer figures cannot be controlled.

It first uses motors to pull in the front seat belts to make sure the occupants are tight against the seat. One of the ways this differs from pretensioners already in some seat belts is that those pretensioners are triggered by an impact and can only be used once without being repaired. With Pre-Safe the pretensioners can be used again and again if somehow a crash is avoided.

Next, if the front passenger’s seat has been reclined too far back, or is moved too far forward, Pre-Safe automatically moves it into a more secure position. Pre-Safe can also tilt the seat cushions up a bit to help prevent the occupant from sliding down or submarining beneath the belts.

Finally, if the system senses the car is going to roll over, Pre-Safe closes the sunroof to keep anything from entering the vehicle — or to keep the occupants from being thrown from the vehicle.

The system on the Lexus models uses a radar sensor to detect obstacles in front of the vehicle and determine whether a crash is inevitable by taking into account factors including the vehicle’s speed and closing rate.

If the computer decides there is no way to stop in time, the system then pre-emptively tightens the front seat belts. It also increases the pressure in the braking system so the brakes will react more quickly as the driver hits the pedal. The idea is to try and lose as much speed as possible before the impact.

It’s too soon for safety researchers to have figured out whether precollision systems can make a significant difference in real-world crashes. There simply are not enough of the systems in use for such an analysis.

However, some safety researchers are enthusiastic about the concept and its potential so that, in 10 years, we all might be benefiting from them.

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