Mercedes-Benz to Unveil Extraordinary Safety Concept At International Auto Show in Frankfurt

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News of August 15, 2001

Mercedes-Benz to Unveil Extraordinary Safety Concept At International Auto Show in Frankfurt

MONTVALE, N.J. - Mercedes-Benz will next month unveil at the 59th International Automobile Fair in Frankfurt Germany (September 13-23) the concept for a vehicle that can detect an imminent collision and engage occupant protection systems before it occurs.

Known as PRE-SAFE(R) (for "Preventive Occupant Safety"), the experimental Mercedes-Benz safety concept combines hazard-detection technology currently in use in Mercedes-Benz passenger vehicles with new types of seatbelt tensioners and automatically adjusting seats. Future versions of the concept would include active body structure and interior components, as well. Mercedes-Benz has already developed the sensor systems and actual protective components of the PRE-SAFE concept to the point that they can be evaluated in test vehicles.

Mercedes-Benz pioneered many of the safety features used in today's vehicles, including high-performance adaptive airbags, door-mounted side airbags and side curtain airbags, seatbelt pretensioners and belt force limiters and crash-optimized body structures. Company safety experts believe that most of the potential in passive safety technology has now been exploited and that further advances will require new concepts.

"Interval of Safety"

The PRE-SAFE concept is based on the findings of Mercedes-Benz accident researchers, which show that in approximately two thirds of all traffic accidents (as studied in Germany) there is a relatively long time interval between the driver's recognition of an impending accident and the impact itself. The researchers believe new technology can activate the vehicle's protection systems during this interval.

"Our present protection systems such as airbags, side curtain airbags or belt tensioners must ensure safety in a matter of milliseconds, even though accident recognition can be measured in seconds," explains Dr. Rodolf Schoneburg, the head of safety development. "Making use of this interval opens up new dimensions in occupant protection."

Mercedes-Benz researchers have already been 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, thereby avoiding expensive repairs.

PRE-SAFE Foundation Already In Place Today

Mercedes-Benz researchers believe that the early recognition of an impending accident and the development of suitable, situation-related occupant protection technology represent the greatest safety engineering challenge of the next few years. This innovative technology is based on systems that use specialized sensors to continuously monitor the driver, vehicle and road surface and are automatically activated when danger is detected.

Several such systems are already installed as standard in current Mercedes-Benz models and recognize critical situations at an early stage to help prevent accidents. The anti-lock braking system (ABS), Brake Assist (BAS) and the Electronic Stability Program (ESP(R)) driving safety systems form the basis for the innovative PRE-SAFE concept.

In the field of occupant protection, Mercedes-Benz introduced the concept of preventive measures more than a decade ago. The outgoing-generation Mercedes-Benz SL coupe/roadster models, introduced in 1989 (1990 in the US), came equipped with the world's first automatic-deploying rollover bar, which deploys in just three-tenths of a second if onboard inclinometer sensors detect a potential rollover. The current CLK-Class Cabriolet is likewise equipped with such an anticipatory rollover protection system.

Protection Can Begin Before an Accident Occurs

In a future PRE-SAFE equipped Mercedes vehicle, the new occupant protection systems would go into action when sensors in the car 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 seatbelts will tension and restrain the driver's and passengers' torsos, preventing their 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 to the rear, while the door panels will move into the car's interior and mold themselves around the occupants' hips like protective shields.

Accident analyses by Mercedes-Benz researchers show 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.

"For Mercedes, PRE-SAFE means the logical continuation of our long-held safety philosophy," says 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 impending crash and therefore give the occupants the best possible protection. Our previous protection concept will therefore be supplemented with an additional PRE-SAFE phase."

Mercedes-Benz Protection Concept With PRE-SAFE

Warning phase: Sensors on the axles and bodywork monitor the vehicle's behavior. When the vehicle's dynamic limits are reached, a yellow warning symbol lights up in the cockpit.
Assistance Phase: Standard dynamic systems such as ABS, Brake Assist and ESP(R) automatically intervene in critical situations and help to make these controllable for the driver.
PRE-SAFE phase: The sensors detect the enhanced probability of an accident. Various safety systems are activated as a precaution to prepare for the possible accident and prepare both the vehicle and its occupants. If the accident is avoided, the PRE-SAFE systems are automatically reset to their original status.
Light impact: In the case of impacts up to about 9 mph, the bumpers and crash boxes in the front-end module absorb the impact energy. Sensors monitor the impact severity and prevent activation of the airbags if their additional protection is not required.
Minor accident: During a more serious impact, robust structural members in the front end, sides and rear end absorb energy and distribute the forces over a wide area. The belt tensioners go into action. Depending on impact severity, the front airbags inflate less than fully to ensure optimal occupant protection. Door-mounted airbags and side curtain airbags provide protection during a side impact. The automatic front passenger and BabySmart(R) child safety seat recognition system prevents activation of the front passenger airbag and belt tensioner if they are not required. The fuel supply to the engine is cut off.
Serious accident: In the event of even greater risk to the occupants a second, additional stage is activated in the front airbags. At the same time, the belt force limiters are activated.
Recovery phase: The doors are automatically unlocked after the accident. The Tele Aid emergency call system (available on all Mercedes-Benz models) alerts emergency services and guides them to the scene of the accident. The hazard warning flasher system is switched on.

Calculating Accident Severity Before The Collision

The Mercedes-Benz PRE-SAFE system relies on sensors that not only recognize a critical dynamic situation, but also provide data from which the computer can predict an accident with a high degree of probability. This enables the electronics to initiate suitable protective measures even before the crash. Mercedes-Benz takes a multi-stage approach with this sophisticated sensor system, which is divided into four sub-systems:

Dynamic sensor system: Evaluates the actual vehicle dynamics and detects critical deviations from the nominal dynamic values. For this purpose it measures, for example, vehicle speed, braking torque, brake pedal speed, wheel slip, acceleration around the vertical axis (yaw), suspension travel, steering speed and tire pressure.
Pre-crash sensor system: Monitors the surroundings using, for example, ultrasonic, infrared or radar technology and image processing to register the distance from a possible obstacle, its relative speed and the possible angle of impact. This system provides information concerning the nature and severity of a possible accident.
Crash sensor system: Recognizes an actual impact within a few milliseconds with the help of acceleration, pressure, intrusion and contact sensors that can even provide information about the ultimate severity of the accident.
Interior sensor system: Establishes which seats in the vehicle are occupied, measures the weights of the passengers, monitors the seatbelt buckles and could in the future also register the exact positions of the occupants using infra-red signals or image processing.

Matching Crash Compatibility With Larger Vehicles

On the basis of these sensor data, a powerful onboard computer prepares the vehicle components and vehicle structure for an impending accident. This involves, for example, extending the bumpers and activating the crash boxes in the front-end structure. Depending on accident severity, these systems would generate forces suitable to absorb a large proportion of the impact energy before it can act on the vehicle occupants.

In the event of an impending side impact with a higher vehicle, such as a large SUV, van or truck, the computer would engage the Active Body Control system (currently used on the Mercedes-Benz CL-Class coupes and certain S-Class sedans) to raise the vehicle body and enhance its crash compatibility with the colliding vehicle. At the same time, the sunroof is automatically closed to prevent the occupants from being ejected in the event of a rollover.

Interior: Seats, Steering Wheel and Door Panels Automatically In Protection Position

In the PRE-SAFE concept, new safety systems in the interior deploy if the electronics have calculated the high probability of an accident. These measures ensure that the occupants are placed in the most protected position possible even before the impact:

n Automatic seat adjustment lowers the seat cushion to the rear if required and adjusts the backrest to the best possible position so that the airbag and seatbelt can function with optimum effect.

n The belt tensioners are already activated before the impact, preventing the occupants from moving too far forward during emergency braking or preventing excessive lateral movements of the torso if the car begins to skid. Tests carried out by Mercedes engineers show that the PRE-SAFE belt tensioner is able to reduce forward body movement by up to 150 millimetres and lateral movement by up to 300 millimetres. This means that the occupants are in the best possible seating position when the impact occurs, enabling the airbags to carry out their protective function to the fullest.

n A knee protector automatically extends from the instrument panel to reduce the forces acting on the legs during a frontal impact. It would also be conceivable to install interior door panels that move towards the occupants before the crash and keep them away from any body components that might penetrate into the interior during the accident. Extending panels on the insides of the B-pillars could provide the same protective function.

Long-Term Objective: Accident-Free Driving With “Thinking" Systems” Mercedes-Benz has set its safety objectives even higher for the long-term future. Company engineers are planning a "thinking" car that is able to recognize its surroundings. This means not only recognizing the road ahead or other vehicles, but also traffic lights, road signs and pedestrians. In addition, Mercedes cars of the future will be able to interpret traffic scenarios and, if necessary, initiate accident prevention measures by themselves.

(Aug. 14, 2001)

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