Friday, November 16, 2001

Imagine your car is about to become involved in an accident but that a new system, currently being developed, can detect the crash and engage occupant protection before it occurs.
Known as Pre-Safe (for Preventive Occupant Safety), the experimental Mercedes-Benz safety concept was unveiled last month recently at the 59th International Automobile Fair in Frankfurt, Germany.
The system combines hazard-detection technology now in use in Mercedes-Benz passenger vehicles with new types of seat-belt tensioners and automatically adjusting seats. The automaker says future versions of the concept will include active body structure and actual protective components.
The system has been developed to the point that it can be evaluated in test vehicles.
Many of the safety features used in today’s vehicles, including performance adaptive air bags, door-mounted side air bags and side-curtain air bags, seat-belt pretensioners and belt-force limiters and crash-optimized body structures were pioneered by Mercedes-Benz.
The automaker’s safety experts believe that most of the potential in passive safety technology has been exploited and that further advances require new concepts.
The Pre-Safe concept is based on findings of the company’s accident researchers. Studies conducted in Germany show that in about two-thirds of all traffic accidents there is a relatively long time interval between the driver’s recognition of an impending accident and the impact itself. Researchers believe that new technology can activate the vehicle’s protection system during this interval.
“Our present protection systems, such as air bags, side curtain air bags or belt tensioners must ensure safety in a matter of milliseconds, even though accident recognition can be measured in seconds,” says Dr. Rodolf Schoneburg, head of the company’s safety development. “Making use of this interval opens up new dimensions in occupant protection.”
Researchers have begun testing a number of conceivable Pre-Safe systems, including automatically extending bumpers, “smart” crash boxes in the front-end structure and even active interior components such as movable interior door panels, sensor-controlled seats and other ideas for preventive occupant protection. If the collision is avoided at the last moment, the Pre-Safe systems would reset themselves to their original status, avoiding expensive repairs.
The technology is based systems that use specialized sensors to continuously monitor the driver, vehicle and road surface and are automatically activated when danger is detected.
Anti-lock braking systems Brake Assist and the Electronic Stability Program driving safety systems form the basis for the Pre-Safe concept.
Mercedes claims that in a future Pre-Safe equipped vehicle, the occupant protection systems would go into action when sensors detect that the vehicle is on a collision course with another vehicle. Even before the driver has time to react and apply the brakes, the seat belts would tension and restrain the driver’s passengers’ torsos, preventing bodies from moving forward during the braking maneuver and ensuring a safe seating position. At the same time, the seat cushions of the front passenger and rear seats will automatically tilt in the rear, while the door panels will move into the car’s interior and mold themselves around the occupants’ hips like protective shields.
Research shows that in two-thirds of all collisions, enough time elapses before the impact to activate such protective systems. In roughly 60 percent of the more than 1,000 reconstructed accidents, the vehicles involved were in a dynamic state that indicated an impending impact.
“Pre-Safe means the logical continuation of our long-held safety philosophy,” according to Dr. Schoneburg. “In the future we will also be able to use the time interval between recognizing a dangerous situation and the point at which the actual impact occurs to prepare the car for the crash and therefore give occupants the best possible protection.”

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