There are two near-range radar sensors in the S-Class's front bumper trim and a long-range radar system in the radiator grille.(Photos: Mercedes-Benz)TECHNOLOGY FOCUSMercedes Autonomous Braking Can Reduce Crash Severity STUTTGART GERMANY - Mercedes Benz is introducing a new autonomous braking feature that it says has the potential to reduce the severity of accidents by up to 40 percent.
The new PRE-SAFE brake system is a self-braking feature that helps drivers avoid collisions by partially engaging the brakes when the vehicle is approaching another car. The new feature will be available as an option on the Mercedes S-Class and CL-Class Coupe this fall.
PRE-SAFE brake works in conjunction with the Mercedes Brake Assist PLUS (BAS PLUS) system, which was introduced last year. BAS provides visual and audible warnings if the car is about to run into another vehicle and automatically calculates the brake force required in order to prevent a crash.
(Graphic: Mercedes-Benz)
With PRE-SAFE braking, if the driver does not react to the BAS warnings and a crash is imminent, the system triggers automatic partial braking approximately 1.6 seconds before the calculated impact and decelerates the car up to 0.4 g (or around 40 percent of the maximum braking performance).
If the driver responds in time and applies the brakes, the severity of the accident can be reduced because the car is already decelerating. In some instances, the accident could be avoided altogether.
"A lot of drivers don't take action as early as they could in an accident situation," says Mercedes spokesperson Michelle Murad. "This gives you precious extra time to respond, which is significant in a crash situation. In tests, we were able to reduce the crash energy by 40 percent."
The 2007 Mercedes-Benz S-Class will include cutting lines embedded in the black shading at the edge of the windshield and the rear window to show rescue workers where to cut the reinforced roof and "A" and "C" pillars. The lines are placed at the thinnest points on the pillars, and help rescue workers avoid cutting into the air bag components.
"The window air bag is close to a pillar, and the pillar itself in most areas is made of high-tensile strength steel. It's difficult to cut through," says Mercedes spokesperson Michelle Murad. "These cut lines are in an area where you're not going to damage the air bag and risk inadvertent deployment, but also in an area where the tubing is not as thick as in the rest of the pillar. It helps the rescue worker cut the pillar with the least amount of danger and minimal amount of delay."
Both BAS and PRE-SAFE use radar technology to determine vehicle proximity. There are two near-range radar sensors in the S-Class's front bumper trim, with a range of 30 meters, as well as long-range radar in the radiator grille with a range of 150 meters. Using the controls on the steering wheel,
the driver activates the system.
Mercedes-Benz tested PRE-SAFE with 500 drivers in field trials in the United States and Germany. Mercedes engineers also tested the system with 70 drivers using DaimlerChrysler Research's simulator in Berlin.
The majority of the 70 simulator participants reacted spontaneously to the warning prompts and were able to avert the accident with support from Brake Assist PLUS; 53 percent of the test drives remained accident-free. Another 17 percent of participants only reacted when autonomous braking occurred, and then manually braked quickly enough to avoid the accident.
In one-third of the simulator tests, drivers were unable to prevent a collision; however, the automatic braking reduced the severity of the accidents by approximately 40 percent. Partial braking reduced the speed of the car from an average of 45 to 35 km/h.
(Source: Mercedes-Benz)
