- DISTRONIC ushers in a new era of safety technology
- PRE-SAFE® prepares the car for an imminent crash
- Pedestrian protection writ large
In 1999, Mercedes-Benz introduced DISTRONIC proximity control, the innovative autonomous intelligent cruise control system. This advanced cruise control system automatically maintains a set distance to other road users. DISTRONIC serves to support the driver’s own alertness. The system uses on-board radar to monitor the distance to the vehicles in front. This value is then compared with parameters such as the speed of the driver’s own vehicle, and DISTRONIC uses this information to compute its reaction, either maintaining or reducing the speed.
With developments such as DISTRONIC, Mercedes-Benz initiated a new era of safety technology in the 1990s, characterized by the linking of passive and active elements. DISTRONIC represented an important step towards improving vehicle safety by means of communication between vehicles. Such assistance systems became increasingly widespread in the years ahead, and these included also systems to monitor the traffic situation behind and to the sides of the automobile.
PRE-SAFE® – not just a seat belt tensioner
The next step in the development of integrated safety was the anticipatory occupant protection system PRE-SAFE® which Mercedes-Benz introduced in 2002. This active passenger protection system operates on the logical assumption that accidents often follow emergency braking. If PRE-SAFE® detects the signs of a pending accident, the mechanical belt tensioners are pre-tensioned with the help of electric motors before the potential accident occurs.
PRE-SAFE® also moves seats and backrests into a particularly safe position and, in addition, closes the sunroof (provided one is fitted and open). PRE-SAFE® does not just sense emergency brake applications, but also unstable driving situations reported by the ESP® and BAS functions, such as skidding and heavy oversteer or understeer which could cause a rollover. Since its debut in 2002 in the S-Class (W 220 series), PRE-SAFE® has been adopted in other Mercedes-Benz models.
The Mercedes-Benz Accident Research department has found that in two thirds of all accidents, there is enough time before the actual collision to initiate preventive safety measures. Vehicle and occupants are then better prepared if a crash occurs. In the event of an accident, the Mercedes-Benz safety system additionally triggers the airbags and belt tensioners to provide the occupants with maximum protection. If the potential accident does not occur, the activated systems can be reset to their original state i.e. they are fully reversible.
The integrated safety concept from Mercedes-Benz
The integrated safety concept from Mercedes-Benz, presented in 2005 in the S-Class from the W 221 series and originally named PRO-SAFE™, combines all elements of active and passive safety in a well-thought-out system – providing protection to the vehicle occupants and other road users. The integrated safety concept brought the design engineers another step closer to realizing the vision of accident-free driving, since it meets to an unprecedented extent requirements for a high degree of vehicle and road safety, as well as being oriented towards real-world accidents.
Among the innovations that made their debut in the S-Class (W 221 series) in 2005 as elements of integrated safety include systems such as DISTRONIC PLUS and Night View Assist. DISTRONIC PLUS is available in combination with Brake Assist PLUS. In the S-Class, the autonomous intelligent cruise control system now operates in a speed range of 0 to 200 km/h (124 mph). DISTRONIC PLUS even continuously maintains the distance to the vehicle in front in stop-and-go traffic, braking the vehicle all the way to a standstill if required.
Brake Assist boosts brake pressure
Brake Assist is not just valuable for preventing rear-end collisions, it also makes an effective contribution to pedestrian protection. This was proven by tests in the Mercedes-Benz driving simulator. The tests involved 55 drivers driving through a town at 50 km/h (34 mph), when a child suddenly runs out onto the road. Only an emergency stop could prevent an accident. The test results showed that drivers supported by Brake Assist had significantly fewer accidents than those whose vehicles were not equipped with the system. Brake Assist reduced the accident rate by 26 percent.
The improved version of this system, Brake Assist PLUS, operates as an anticipatory system to support the driver more effectively in critical situations. This is made possible by radar technology. The system monitors the area in front of the vehicle and computes the required brake servo assistance when an accident is about to occur. When the driver steps on the brake pedal, the new Brake Assist PLUS system instantaneously builds up the brake pressure computed for the respective situation. Whereas ordinary brake assistance systems require a “knee-jerk” response from the driver to operate (i.e. an unusually rapid depression of the brake pedal), the new system detects that the driver wishes to brake as soon as the pedal is touched and automatically boosts the brake pressure depending on the situation. The system therefore ensures that one of the most important requirements for accident avoidance is fulfilled, namely the best possible deceleration for the respective situation.
Comprehensive pedestrian protection
Many of the activities and safety measures introduced to protect pedestrians and cyclists in past decades are results of Mercedes-Benz initiatives. Smooth-surfaced bodies, energy-absorbing bumpers, laminated-glass windshields, folding exterior mirrors, rounded door handles and recessed windshield wipers are just some of the features of Mercedes-Benz passenger cars that serve to protect pedestrians.
The additional safety precautions that Mercedes-Benz has implemented in the S-Class (W 221 series) as well as in the E-Class sedan (W 212) and the coupé (C 207) complement this already high level of protection. The lower part of the engine hood is designed in such a way that it easily deforms during a collision with a pedestrian and absorbs impact energy. A new type of hinge which yields to allow the engine hood to deform also makes a contribution to minimizing pedestrian and cyclist injuries. The front fenders of the new Mercedes-Benz sedan are connected to the upper longitudinal members by means of special fasteners. The rigidity of the structure is precisely calculated allowing it to give way during a collision. The deformation space between the engine hood and the major assemblies beneath has also been increased.
Turning night into day
The Night View Assist system introduced to the S-Class operates using infrared headlamps that illuminate a much greater area of the road surface in darkness than the standard low-beam headlamps. The image captured by the infrared rays, which are invisible to the human eye, is displayed in the instrument cluster.
In darkness, Night View Assist provides the driver with a much greater range of vision than that provided by ordinary headlamps operating in low-beam mode. This means that the driver can see more of the course of the road and detect pedestrians, cyclists or obstacles on the road at an earlier stage. Even when the headlamps of oncoming vehicles dazzle the driver, seriously impairing his or her vision, this assistance system allows the driver to see much more clearly regardless. In tests, the Night View Assist system allowed drivers to detect a dummy wearing bright clothing that was standing at the side of the road 50 meters (164 ft) behind an oncoming vehicle at an average distance of 140 meters (459 ft.) – approximately 53 meters (174 ft.) sooner than with bi-xenon low-beam headlamps.
Intelligent illumination technology ensures good vision
The Intelligent Light System also serves to improve safety during night-time driving; this made its debut in 2006 in the E-Class. It incorporates variably controllable headlamps with five different illumination functions. Mercedes-Benz upgraded the bi-xenon low beams with their tried and tested asymmetric light distribution by adding a new country-road light mode that increases illumination of the left-hand edge of the road and illuminates a broader range than before. This function enlarges the driver’s range of vision by approximately 10 meters (33 ft.), improving ease of orientation in darkness and making it possible to react more quickly when other road users cross the road.
At speeds above 90 km/h (56 mph), the new motorway light function automatically switches on in two stages. Firstly, the output of the xenon bulbs is increased from 35 to 38 Watts, and secondly, the range of the headlamp positioned on the inside of the lane is extended at speeds above 110 km/h (68 mph). This produces a uniform light cone that reaches up to 120 meters (394 ft.) in length and illuminates the road over its entire width. At the centre of this light cone, the driver can see approximately 50 meters (164 ft.) further than with the previous low-beam versions, allowing him/her to detect vehicles at great distances and adapt his/her driving style accordingly.
With the extended fog light function, which belongs to the new Intelligent Light System, Mercedes-Benz also improved the ease of orientation in fog. As soon as the rear fog lamp is switched on when visibility is less than 50 meters (164 ft.) and vehicle speed is below 70 km/h (43 mph), the left bi-xenon headlamp of the E-Class swivels 8 degrees to the outside and lowers its light cone at the same time. This improves the illumination of the inner half of the road. Wider light distribution also prevents the driver from being dazzled by the light reflected by the fog. The extended fog light remains switched on up to a speed of 100 km/h (62 mph).
The active light function, which Mercedes-Benz first offered in the E-Class in the spring of 2003, is now part of the Intelligent Light System. The swivel range of the headlamps has been increased from 12 to 15 degrees, allowing tight corners to be illuminated more effectively. With the active light function, which operates with both high and low beams, the bi-xenon headlamps automatically follow the steering angle. It thus improves road illumination in curves by up to 90 percent.
The Intelligent Light System also incorporates the cornering light function, whereby one of the two front fog lamps automatically switches on when the driver activates a direction indicator or turns the steering wheel. This illuminates the side area in front of the vehicle to a range of approximately 30 meters (98 ft.). The cornering light switches on at speeds of up to 40 km/h (25 mph).
Head restraints to prevent whiplash injury
Another special safety feature that is gradually being adopted in all Mercedes-Benz passenger cars goes by the name of NECK-PRO. This is the Mercedes-Benz designation for a new type of head restraint, which, like PRE- SAFE®and other Mercedes-Benz innovations, is based on the analysis of real-world accidents. NECK-PRO is an effective feature that reduces the risk of injury to the cervical vertebrae during a rear-end collision. Whiplash injury, which is caused by the rapid whip-like forward and backward movement of the head and overextension of the cervical vertebrae in an accident, is one of the most frequent types of accident injury in Europe with an annual cost to the economy of around eight billion euros, according to estimates of the EU Commission.
NECK-PRO is a sensor-controlled, active head restraint which is activated in the event of a rear-end collision. If the measuring sensors detect a collision of this type and above a pre-defined minimum level of severity, they release pre-compressed springs inside the head restraints. Within milliseconds, these adjust the padded areas of the head restraint some 40 millimetres (1.57 in) forward and 30 millimetres (1.18 in) upward. This provides the heads of the front seat passengers with support at an early stage of the accident in order to prevent overextension of the cervical vertebrae due to the collision.
After the NECK-PRO head restraints have been triggered, they can be manually reset to their starting position and are ready for re-use immediately.
E-Class from the 212 series: Setting standards in vehicle safety
Presented in 2009, the E-Class from the 212 series features over a dozen assistance systems which enable it to set new standards in active safety. These safety systems include tried-and-trusted technologies such as ABS, ESP®and Brake Assist, as well as new solutions. Among these is the standard-fit ATTENTION ASSIST, which uses over 70 parameters to monitor driver behaviour and identify the onset of drowsiness. Drowsiness is responsible for one quarter of all motorway accidents and therefore one of the commonest causes of accidents. Studies have shown that tired drivers make minor steering errors, so ATTENTION ASSIST uses a highly sensitive steering angle sensor to identify signs of driver drowsiness. When this is the case, the system gives the driver an acoustic and visual warning that it is time to a take break.
The E-Cass portfolio of active safety measures also includes Adaptive Highbeam Assist, which ensures optimum headlamp range in different driving situations at night. The Lane Tracking package is an optional system that offers various assistance systems to help keep the driver stay in lane and change lane safely when overtaking. If Lane Keeping Assist detects that the car is leaving the marked lane unintentionally, it warns the driver by means of vibrations in the steering wheel.
Whereas Lane Keeping Assist uses data from a camera mounted on the inside of the front windscreen and processes information concerning vehicle dynamics, Blind Spot Assist evaluates signals from short-range radar sensors housed on both sides of the rear bumper. This enables the E-Class to warn its driver of lane changes made by other vehicles which may be concealed in the driver’s “blind spot”.
Another innovative contribution to accident avoidance from Mercedes-Benz available in the 212 series is the new Speed Limit Assist, which monitors road signs and digital road maps to determine the speed limit currently in force and displays this in the cockpit. This assistance system also receives its signals from the camera mounted on the inside of the front windscreen.
Rounding off the safety equipment of the E-Class is the PRE-SAFE® Brake and DISTRONIC PLUS, incorporating a radar-based proximity control and Brake Assist. In critical situations involving a direct threat of impact, these assistance systems are capable of bringing the vehicle to a standstill under emergency braking if necessary.
In terms of passive safety, too, the E-Class has shown itself to be a worthy heir to vehicles from the upper mid-range of Mercedes-Benz, throughout whose history the brand repeatedly introduced milestones in vehicle safety. Passive safety features include Active Bonnet for improved pedestrian protection, larger crumple zones at front and rear and up to seven airbags and four standard-fit belt tensioners.
In addition, the engineers have also introduced key improvements to the efficiency of the PRE-SAFE® system for preventive occupant protection. This multi award-winning technology is standard equipment in the E-Class and offers a greater range of functions than previously. Early accident recognition is possible because PRE-SAFE® creates an intelligent synergy of active and passive safety features. It is networked to Brake Assist and the Electronic Stability Program ESP®, whose sensors recognise potentially critical dynamic handling situations and then transmit this information within milliseconds to the electronic control units. Where PRE-SAFE® previously responded to emergency or panic braking – in other words when the driver hit the brake pedal reflexively – the new system in the E-Class can also be activated if the optionally available DISTRONIC PLUS system’s short- and long-range radars have detected an impending head-to-tail collision and a certain level of deceleration is exceeded when braking. The occupants are prepared for the collision by tensioning the seat belts and repositioning the optionally available, fully electrically adjustable front-passenger seat (if Memory function is available), enabling the seat belts and airbags to be activated and deployed with maximum effect.
The car as intelligent partner
The integrated safety concept from Mercedes-Benz is a comprehensive package that turns the vehicles into the driver’s intelligent partner. For with state-of-the-art sensor systems and corresponding data processing, cars are now playing a bigger part in active safety than ever before. Radar, cameras and sensors now provide the basis for vehicles to respond to situations as if by reflex and act independently.
The facelifted S-Class of 2009 also offers a combination of state-of-the-art assistance and protection systems that is unique worldwide, including technologies introduced in the E-Class from the 212 series that same year. In addition, the Mercedes-Benz developers modified Active Body Control (ABC) to include the additional function of crosswind stabilization. This comes as standard in the S 600. For this purpose ABC uses the yaw rates and lateral acceleration sensors of the Electronic Stability Program ESP®to vary the wheel load distribution via the ABC spring struts within milliseconds, depending on the direction and intensity of the crosswind. This enables the effects of a crosswind to be largely compensated – or at least minimized in the event of strong gusts.
Extra safety at the physical limits, as well as more agility, is provided by the Torque Vectoring Brake in the 2009 S-Class – targeted, one-sided braking intervention at the inside rear wheel when cornering so that the saloon turns into the bend precisely and without any loss of handling dynamics.
When added together, these measures make Mercedes-Benz automobiles real partners for their drivers, without compromising their independence at the wheel. This has been the goal throughout the brand’s long history. And it remains the goal for the future.