Concept Vehicles

The Mercedes-Benz ESF 2009 Experimental Safety Vehicle: PRE-SAFE Pulse and Air Bags

Words Chris Danielson | June 10, 2009
As a further development, PRE-SAFE Pulse is able to reduce the loads acting on the torsos of the occupants by around one third
Words Chris Danielson June 10, 2009

With the multiple award-winning PRE-SAFE® system, Mercedes-Benz has once again been underlining its role as a pioneer in the safety field since 2002: once the system recognises certain critical driving situations, PRE-SAFE® activates occupant protection measures as a precaution. As a further development, PRE-SAFE Pulse is able to reduce the loads acting on the torsos of the occupants by around one third during a side impact by preventively moving them towards the centre of the vehicle.

Out of harm’s way – every millimetre counts during an accident. When an impending lateral collision is recognised, PRE-SAFE Pulse as an active restraint system moves the driver and front passenger towards the centre of the vehicle, using air chambers in the side bolsters of the seat backrests. If the onboard sensors report that a side impact is inevitable, these are inflated within fractions of a second and give the seat occupants a slight nudge in the ribs. This impulse is enough to move them out of the danger zone by up to 50 millimetres. Even before the accident, it also accelerates the seat occupant in the direction he/she will later take during the accident. This reduces the loads acting on the occupant during the impact. The seat does not need to be replaced or repaired when this preventive safety system has been activated, as PRE-SAFE Pulse is reversible.

PRE-SAFE Pulse is being developed on the basis of the dynamic multicontour seat in the new Mercedes E-Class. Depending on the steering angle, lateral acceleration and speed, the inflation pressure and volume of the air chambers in the side bolsters of the seat backrests are already varied to give the driver and front passenger even better lateral support.

Partial main beam: full beam ahead at all times

Whether as brake lights and indicators in many Mercedes models, or as daytime driving lights in the new E and S-Class, LED lighting technology is seeing increasing use at Mercedes-Benz. And things will be brightening up at night as well in future: Mercedes lighting specialists are working on an adaptive LED main beam system that automatically excludes oncoming traffic from the cone of light. A special spotlight function also allows potential hazards to receive additional illumination.

Main beam, low beam, main beam… anybody travelling on country roads in western Europe at night is seldom able to drive with the main beams on for very long. The frequency of oncoming traffic dictates that the driver is soon obliged to switch to low beam, either manually or more conveniently using the Main Beam Assist in the new Mercedes E-Class. This is not enough to satisfy the researchers at Mercedes-Benz, however. Because during the phases when the driver switches to low beam – with its shorter range – to avoid dazzling others, it is possible to overlook other road users or potential hazards.

The lighting specialists at Mercedes-Benz are therefore working on an LED-based adaptive main beam system. This enables the driver to leave the main beams switched on constantly. As soon as the system detects oncoming traffic with the help of a camera, it automatically adjusts the light distribution accordingly. The Mercedes ESF 2009 experimental safety vehicle shows precisely how this works. A headlamp is made up of 100 LEDs. These semiconductor elements can be individually activated, so that when there is oncoming traffic, the precise beam area in which other road users are located can be darkened down. The system recognises these using an infrared camera. The purely electronic module is also able to respond much faster than present electro-mechanical shutter/roller assemblies.

The light distribution can also be refined in the opposite direction: a special spotlight function in the LED array of the research vehicle also enables potential hazards to be highlighted. If the infrared camera detects pedestrians in the road ahead, for example, they can be briefly lit up beyond the normal main beam illumination, as if by an aimed spotlight. The driver is thus alerted to the potential danger.

Side Reflect: not all Mercedes are grey at night

Reflective material on the body and tyres could further improve the lateral visibility of vehicles, and help to avoid accidents at road junctions.

Reflective materials have long been commonplace in children’s clothing, and in the case of bicycles it is even mandatory to have reflectors in the wheel spokes. So the engineers at Mercedes-Benz asked themselves why the perceptual safety of cars could not be improved in the same way. Accordingly the ESF 2009 research car features appropriate reflective elements when viewed from the side. These modifications are not visible during the daytime, but the additional benefit shows up when dusk and darkness fall.

Together with the manufacturer Continental, Mercedes specialists have developed a reflective strip on the tyres which visually enlarges the wheels in daylight and creates an easily visible band of light when illuminated at night. As a further safety feature there are reflective seals between the doors and the roof, a joint development with the adhesive foil specialist 3M. The aim is to make the vehicle’s silhouette more easily visible in the dark. This enables potential accident situations on junctions or in the form of unlit, parked vehicles to be defused.

Reflective foils consist if a reflective base layer with tiny balls of glass. When a ray of light hits the foil, it is refracted by the glass balls, reflected by the base layer and refracted again on exiting. As a result, most of the light is reflected back in its original direction.

Belt Bag: a clever combination of a seat belt and airbag

The seat belt is regarded as one of the most important inventions of the 20th Century, and has saved countless lives. It has been further improved with belt tensioners and belt force limiters, but that is not the end of its development: an innovative extension to the width of the belt, known as a Belt Bag, is able to reduce the risk of injury even further in an accident.

When a seat belt limits the movement of its wearer’s torso as intended during a collision, it subjects the body to considerable forces. The Belt Bag, on whose development Mercedes-Benz is working intensively with the seat belt specialist Autoliv, practically doubles its width within fractions of a second during an accident. This increase in the width of the belt spreads the pressure over a wider area, thereby reducing the risk of injury. This is particularly beneficial for older passengers, whose ribcage is no longer so flexible.

As the name suggests, the Belt Bag is a combination of a seat belt and airbag. When the crash sensors detect a serious impact, the airbag control unit activates the Belt Bag. A generator at the belt armature inflates the double-layered belt, which has Velcro seams. The volume of the Belt Bag is around four litres. The developers consider the Belt Bag to deliver the greatest benefits in the rear of the car, where conventional airbags cannot be installed. It is therefore conceivable that the Belt Bag could be used here by Mercedes-Benz in the foreseeable future.