Mercedes ESF S400 Hybrid Concept 2009 In Depth with 3 Videos

By Thami Masemola
June 11, 2009 7:26 PM
Filed Under: Concept Car, German, Mercedes-Benz, Technology

This year Mercedes-Benz celebrates a few anniversaries such as the principle of the crumple zone, invented in 1939 and the in-house accident research function in 1959. In 2009 the company is introducing its first Experimental Safety Vehicle in 35 years, the ESF 2009. The aim of the car is to illustrate innovative safety features that could make it into production.

The ESF is based on the S 400 Hybrid. One of the ideas installed in the car is something called a Braking Bag. It is an air bag that sits within the ESF's floor and deploys when the car "decides" that a crash is imminent. By increasing friction with the road surface it helps to slow the vehicle down and also stabilises it.

"Safety is a central element of the Mercedes-Benz brand," says Dr. Dieter Zetsche, Chairman of Daimler AG and CEO of Mercedes-Benz Cars. "In this respect we have been setting the pace in the market for almost 70 years. For the benefit of our customers and for road users in general. The ESF 2009 shows that we still have plenty of ideas and the absolute will, to lead the automobile industry in this field even in future."

Interactive Vehicle Communication is another innovation of the ESF 2009. The IVC system allows cars travelling in opposite directions to communicate with each other in order to warn of upcoming bad weather or road obstacles.

There's also PRE-SAFE Pulse which moves passengers towards the centre of the car by up to 50mm. It does this to reduce the forces acting on their torsos during a lateral collision. The other safety piece is the partial LED main beam which specifically illuminates potential hazards that are detected to be outside of the normal illuminated area.

The ESF 2009 will be presented on the 15th of June at the Enhanced Safety of Vehicles (ESV) Conference in Stuttgart.

Fully detailed press release on the following 15 pages.

Press Release

Perspectives: inflatable metal structures and braking airbags in the vehicle floor

2009 is a year in which Mercedes-Benz celebrates several anniversaries in the safety field: in August 1939 the safety pioneer Béla Barényi started his work in Sindelfingen. He invented for example the principle of the crumple zone, a trailblazing innovation which entered series production at Mercedes-Benz in 1959. With the help of its in-house accident research function, which was founded in 1969, Mercedes engineers in the following years have developed several groundbreaking innovations in passenger car safety. Now it is time for a look behind the scenes, and in this anniversary year, Mercedes-Benz is using the ESF 2009 research vehicle to reveal what its safety specialists are currently working on - with a time horizon that often extends well into the future.

The ESF 2009 is the first Experimental Safety Vehicle to be built by Mercedes-Benz since 1974. Like its historic predecessors, it illustrates trailblazing innovations in the field of safety and makes the progress achieved clearly visible. These amazing but by no means crazy ideas include inflatable metallic sections which give more stability to structural components within fractions of a second, as well as the so-called "Braking Bag". This airbag housed within the vehicle floor is deployed when a crash is deemed to be unavoidable, and uses a friction coating to support the vehicle against the road surface. The ESF 2009 will be premiered on 15 June 2009, at the Enhanced Safety of Vehicles (ESV) Conference in Stuttgart.

"Safety is a central element of the Mercedes-Benz brand. In this respect we have been setting the pace in the market for almost 70 years. For the benefit of our customers and for road users in general. The ESF 2009 shows that we still have plenty of ideas and the absolute will, to lead the automobile industry in this field even in future", says Dr. Dieter Zetsche, Chairman of Daimler AG and CEO of Mercedes-Benz Cars.

The ESF 2009 was developed and built completely in the test vehicle workshops in Sindelfingen. This safety research vehicle based on the Mercedes S 400 HYBRID features more than a dozen safety innovations, most of which are fully functioning in demonstration mode. "With the ESF 2009, we have chosen this particular time to clearly demonstrate the innovative strength of Daimler. Anybody examining the ESF 2009 in detail will recognise that more safety and improved energy efficiency are not necessarily a contradiction in terms. We want to make progress in both fields with new, trailblazing ideas ", says Dr. Thomas Weber, the member of the Daimler Executive Board responsible for corporate research and development at Mercedes-Benz Cars.

The following five innovations on the basis of the S 400 Hybrid are among the highlights of the ESF 2009:

* PRE-SAFE Structure:The inflatable metal structures save weight or increase the stability of structural components. When at rest, the metal section is in a folded state to save space. If its protective effect is required, a gas generator builds up an internal pressure of 10 to 20 bar within fractions of a second, causing the section to unfold for significantly more stability.

* Braking Bag:This auxiliary brake accommodated in the vehicle floor is a new type of PRE-SAFE® component. If the sensor system concludes that an impact is unavoidable, the Braking Bag is deployed shortly before the crash and stabilises the car on the road surface by means of a friction coating. The vehicle's vertical acceleration increases the friction, and helps to decelerate the vehicle before the impact occurs.

* Interactive Vehicle Communication: The ESF 2009 is able to communicate directly with other vehicles, or via relay stations. Using "ad hoc" networks and WLAN radio technology, it is e.g. able to receive and transmit warnings of bad weather or obstacles in the road.

* PRE-SAFE Pulse: This further development of PRE-SAFE® is able to reduce the forces acting on the torsos of the occupants during a lateral collision by around one third. It does this by moving them towards the centre of the vehicle by up to 50 millimetres as a precautionary measure. As an active restraint system, it uses the air chambers in the side bolsters of the seat backrests.

* Spotlight lighting function: This partial LED main beam specifically illuminates potential hazards. If the infrared camera of Night View Assist PLUSe.g. detects deer at the roadside or pedestrians on the road, these can be briefly illuminated beyond the normal area covered by the main beams, as if by a spotlight.

Mercedes-Benz is also presenting an innovative PRE-SAFE Demonstrator at the 21st ESVConference. For the first time this simulator uses a linear motor for this purpose, in order to accelerate the vehicle cabin to up to 16 km/h within a distance of four metres before the impact occurs. The linear drive system, which is similar to that used by the Transrapid train, is freely programmable and also works in the opposite direction. This enables various acceleration profiles and also a rear-end collision to be demonstrated. The special feature of this system is that the 'vehicle occupants' experience the effect of the PRE-SAFE® functions live, e.g. belt pretensioning, NECK-PRO and the inflatable side bolsters of the seats.

Mercedes-Benz is continuing a longstanding tradition with the ESF 2009: for the ESV Safety Conferences held in 1971 to 1975, the safety experts in Stuttgartbuilt more than 30 experimental vehicles and subjected them to crash tests to satisfy the visionary safety requirements of that time. Four of these ESFs (Experimental Safety Vehicles) were presented to the public, and many of the revolutionary ideas such as ABS or the airbag first entered series production at Mercedes-Benz.

 

PRE-SAFE Structure: inflatable metal structures

It sounds like science-fiction: concealed metallic structures that wait patiently in a collapsed, space-saving state until they are required to go into action. Daimler researchers working together with the gas generator specialists at Autoliv spent two years actively researching such active metal support systems, and tested a variety of applications. For the very first time, inflatable metal side impact protection can be seen in the ESF 2009.

Imagine an inflatable mattress. When it is not needed, it is rolled up flat and e.g. consigned to a shelf in the attic. When inflated, however, it has a highly resistant structure that can easily carry a man weighing 100 kilograms. Inflatable metallic structures work in the same way: when not in use, the metal section is folded together to save space. Once its protective effect is needed, a gas generator just like those used to inflate airbags builds up an internal pressure of 10 to 20 bar within fractions of a second, the metal section is unfolded and the structure has significantly greater stability.

The advantages are obvious, and mainly involve packaging and weight: more stable structures can be accommodated within the increasingly tight installation spaces of an automobile, or weight can be greatly reduced while maintaining the same stability. Using the example of the side impact protection member in the doors of the S-Class, the researchers have calculated that around 500 grams less weight per door would be feasible.

Daimler safety researchers examined various applications for these innovative, crash-responsive metal structures, among them side impact protection, the side skirts and the seat cross-members. These have the advantage of being several centimetres away from the impact zone. The gas generator therefore only needs to be activated when a crash has definitely taken place.

One of the still unsolved problems of these protective members is that unlike the PRE-SAFE® measures already in series production, their active deformation is not reversible. Moreover, the activation of protective members installed well to the outside of the bodyshell that can be inflated by internal pressure requires their deployment before the crash. The pre-crash sensor system must therefore provide highly reliable signals.

Another hurdle is the currently still uncompetitive cost level of the required gas generators in relation to the cost requirements for weight-saving measures. These crash-responsive metal structures are therefore still a thing of the future - but the same was also once true of standard safety features like the airbag, ABS or ESP®.

PRE-SAFE Pulse: an automatic nudge in the ribs

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.

PRE-SAFE 360°: full emergency braking before an impact

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 360° monitors not only the areas to the side, but also to the rear of the vehicle.

PRE-SAFE 360° uses short-range or multi-mode sensors to monitor the area behind the vehicle to a range of up to 60 metres. If the accident early-warning system registers that a collision is unavoidable, the brakes are applied around 600 milliseconds before the impact. If the already stationary car is braked during a rear-end collision, this not only prevents secondary accidents where the car is e.g. uncontrollably shunted into a road junction or onto a pedestrian crossing. The severity of possible whiplash injuries to the occupants can also be reduced by application of the brakes, as the vehicle and therefore its occupants have less forward acceleration. The driver always has the final decision with PRE-SAFE 360°, however: if he accelerates because he is able to prevent the rear-end collision by moving forward, for example, the brakes are instantly released.

Contrary to the widely held opinion among drivers, it does not make sense to take one's foot off the brake pedal before an impending rear-end collision. The correct action would be to apply the brakes as hard as possible, however accident research findings show that the driver of a stationary vehicle impacted from the rear is moved backwards by up to 20 centimetres. This inevitably causes his feet to slip from the pedals.

The protective effect of PRE-SAFE 360° supports that of the NECK-PRO crash-responsive head restraints, which are already standard equipment in many Mercedes model series. If the sensor system detects a rear-end collision with a
defined impact severity, it releases pre-tensioned springs inside the head restraints, causing the head restraints to move forward by about 40 millimetres and upwards by 30 millimetres within a matter of milliseconds. This means that the heads of the driver and front passenger are supported at an early stage than with conventional head restraints.

PRE-SAFE Demonstrator: a realistic PRE-SAFE® experience

The preventive occupant protection system PRE-SAFE® activates a number of safety systems if an accident appears to be unavoidable. Fortunately, many drivers never find themselves in a situation where they can experience PRE-SAFE® for themselves. A realistic impression of these safety systems is provided by an innovative PRE-SAFE Demonstrator, which will have its world premiere at the 21st ESV Conference in Stuttgart on 15 June.

For the first time for this purpose, the simulator uses a linear motor to accelerate the vehicle cabin to up to 16 km/h within a distance of four metres. This corresponds to an acceleration of two g, i.e. twice freefall speed. After around 1.2 seconds the cabin impacts the specially designed hydraulic shock absorbers. In the interim the occupants not only experience the effects of the PRE-SAFE® functions at first hand, e.g. belt pretensioning, NECK-PRO and the inflatable side bolsters on the seats, but also the restraining effect of the seat belts during the impact.

The linear drive of the PRE-SAFE Demonstrator, which is similar to that of the Transrapid train system, has a power consumption of 10 kW, is freely programmable and also works in the opposite direction. This enables various acceleration profiles, and also a rear-end collision, to be demonstrated. The cabin can also be rotated by 30 degrees on its sledge to simulate an oblique impact. If the cabin is rotated by 90 degrees, the drive system can be programmed a produce to-and-fro motion that gives the impression of taking corners at high speed.

The moving mass of the Demonstrator is 500 kg. This includes the cabin, which was created from a real S-Class saloon whose front passenger seat, dashboard and door were adopted. To keep the Demonstrator compact in size, the driver's side, engine compartment and the body section to the rear of the B-pillar were removed. Specially designed plastic components close off the cabin at these points. The Demonstrator weighs a total of around 2.5 tonnes, and is designed to be easily loaded onto a vehicle by fork-lift truck. Easy transport is also facilitated by the double electrical interfaces directly on the Demonstrator and at the control console. The unit has hydraulically extendable rollers to allow precise placement at the destination.

The PRE-SAFEDemonstrator was developed and designed on behalf of the Mercedes accident research department by the prototype production function of MB-technology GmbH. The MBtech Group is a globally operating automotive engineering and consulting business within the Daimler group. Project manager Markus Pscheidt recalls: "This commission was a very special challenge, for as far as we were aware, a linear drive system had never been used for automotive purposes. To ensure the safety of the cabin's occupants under all circumstances, we had to design many of the features ourselves in close consultation with the TÜV safety inspectorate."

 

Braking Bag: a braking parachute for the car

Airbags in cars have previously only been used as a restraint system for the occupants. In the future they might also be a PRE-CRASH- component, activating an auxiliary brake in the vehicle floor and improving both deceleration and compatibility with the other vehicle involved in the accident.

Energy is not only reducible by braking the road wheels: jet fighters and dragsters use braking parachutes, for example. And as early as 1952, Mercedes-Benz was already experimenting with an air-brake at the Le Mans race: when decelerating, the driver was able to move a metal panel on the roof of his racing SL to a vertical position. Even earlier, coachmen used special wheel chocks. These were placed in front of one of both rear wheels on long downhill gradients, and their iron-clad base helped to brake the vehicle during the descent.

This is an old idea that Mercedes safety researchers have revitalised on a similar principle with the Braking Bag, an airbag installed between the front axle carrier and the underbody panelling. If the sensor system concludes that an impact is inevitable, the PRE-SAFE® system not only initiates automatic emergency braking. At the same time the Braking Bag is deployed just before the crash, supporting the car against the road surface by means of a friction coating. The vehicle's vertical acceleration increases the friction and has an additional braking effect before the impact. The Braking Bag uses the PRE-CRASH sensors in Mercedes-Benz cars, which are already able to initiate preventive occupant protection measures in critical driving situations.

There are several advantages to this unusual auxiliary brake:

* The rate of deceleration is briefly increased to over 20 m/sec/sec. This scrubs additional energy beyond the potentials of a wheel brake, thereby reducing accident severity.

* Because the car is raised upwards by up to eight centimetres within a short time, the dive effect that occurs with conventional brakes is substantially compensated. This improves geometrical compatibility with the other party in an accident.

* This vertical movement also improves the effects of the restraint systems: the seats move towards the occupants by around three centimetres, which enables the belt tensioners to take up more slack. The high deceleration rate before the impact has a "pretensioning" effect on the occupants, so to speak.

* Downward support for the vehicle during the crash reduces the typical diving motion during a collision.

All in all, the braking airbag has the effect of an additional crumple zone. Mercedes engineers have calculated that even at a low 50 km/h, the additional deceleration has the same effect as lengthening the front end by 180 mm. Initial driving tests in a C-Class have already shown the effectiveness of this new auxiliary brake - though it will still be some time before the Braking Bag becomes another component of the PRE-SAFE® system.

 

Interactive Vehicle Communication: cars report what their sensors have detected

Cars sometimes know more about their surroundings than their drivers. With the help of intelligent communication systems, vehicles themselves are able to contribute to improved road safety and mobility.

A patch of black ice on the next bend? A bank of fog three kilometres down the road? A new traffic tailback where roadworks are being carried out? What used to come as an unpleasant surprise is far less frightening if the approaching driver receives an up-to-date is warning beforehand. This is a task that will in future be carried out by the other vehicles on the roads at the time - automatically, by radio. This is the basic idea behind Interactive Vehicle Communication.

Cars are nowadays able to collect a great deal of information about the current driving situation, as the numerous sensors, cameras and control units for the dynamic and assistance systems can register e.g. poor weather conditions just as well as sudden braking and avoiding manoeuvres, or broken-down vehicles on the road. There are also other sources of information, for example local police reports. This information can be passed on via additional relay stations ("car-to-x") such as radio masts at the roadside, stationary nodal points (e.g. traffic centres and overhead gantries) or via the internet. The onboard computer classifies all the reports according to plausibility and relevance. Tailback reports on the radio which are out-of-date or irrelevant to the individual driver will then be a thing of the past.

Mercedes engineers have been working on "Interactive Vehicle Communication" as a technology of the future for more than seven years. The ESF 2009 safety concept vehicle demonstrates the current status of this research: this Mercedes can automatically recognise an approaching police car, for example, and warn its driver by showing a symbol in the display. It is also possible to send and receive warnings of bad weather or obstacles in the road.

The exchange of data between vehicles is via so-called "ad hoc" networks, connections that are spontaneously formed between the vehicles over short distances. These wireless local area networks (WLANs) are self-organising, and require no external infrastructure. Transmission and reception is at a frequency of 5.9 gigahertz, over a distance of up to 500 metres. In fact the achievable communication range is much greater, as oncoming vehicles pass the messages on.

Cars that communicate with each other can do more than just pass on information: linked to modern proximity control systems such as DISTRONIC Plus from Mercedes-Benz, they can help to harmonise the traffic flow and avoid tailbacks by automatically selecting the most suitable vehicle speed when joining a motorway. And collisions can be avoided if onboard sensors recognise an impending accident and automatically regulate the distance.

This technology is currently demonstrating its practicality in the "Safe Intelligent Mobility - Test area Germany" project (simTD), in which Mercedes-Benz and other German manufacturers and suppliers are taking part. Up to 400 vehicles communicate with each other in these, the world's largest field trials for Interactive Vehicle Communication. simTD is being conducted in the densely populated Frankfurt/Rhine-Main area from autumn 2008 to 2012. Experts expect usable mobile information networks with full coverage to become a possibility when around ten percent of all vehicles have this communications capability.

 

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.

 

Child Protect: safety and comfort for very small passengers

Mercedes engineers have thought about how children might travel even more safely in a car.

The two major advantages of the Mercedes concept study "Child Protect" over conventional child safety seats are an improved protective effect and greater comfort for the child. This is accompanied by a high level of quality and attractive visual integration of the seat into the interior of Mercedes models. This system jointly designed with the restraint system specialist Takata is suitable for children aged between three and 12 years (weight categories II and III). One special feature is its modular construction, as the height and width can be individually adapted to the child's physical proportions.

"Child Protect" has a tubular frame construction. This design offers better support and greater rigidity than versions of moulded plastic during a side impact. The prominent side bolsters in the shoulder and head area keep the child in place and minimise body movement during an accident. At the same time they prevent the child from coming into contact with vehicle components penetrating into the interior, or with the passenger in the adjacent seat. This seat study, which is approved according to the ECE R44.04 standard, is also equipped with automatic, sensor-controlled airbag deactivation on the front passenger seat.

As an additional benefit, Mercedes engineers are considering the addition of a buggy subframe to the child seat. This would also ensure that children travel in comfort, style and safety outside the car.

 

Size Adaptive Airbags: tailor-made airbags

The 1980 Mercedes S-Class (W 126) was the first series production car equipped with an airbag. In the meantime airbags have firmly established themselves across all vehicle segments. Airbags have saved many human
lives and reduced the severity of injuries. Mercedes safety specialists are now working on a further improvement to their protective effect by developing airbags with a variable volume.

There are already adaptive airbags at Mercedes-Benz today, for in many model series the airbags are activated in two stages depending on the assessed severity of the impact. Future generations of this restraint system will not only take accident severity into account, but adapt themselves to the individual vehicle occupants: "Size Adaptive Airbags" automatically adjust their volume to the seating position and stature of the front passenger as recognised by the sensors. For whether a small front passenger is hunched up close to the dashboard or a tall front passenger has his seat moved well back is certainly a factor in the protective effect of the airbag. The weight of the front passenger, and therefore the forces acting on the airbag during an accident, are also important.

"Size Adaptive Airbags" enable occupant contact with the airbag to be optimally timed, whatever his weight and seating position. The restraint system can therefore dampen the impact to optimum effect. This Mercedes development varies the volume on the front passenger side between 90 and 150 litres. For purposes of comparison, conventional front passenger airbags have a volume of around 120 litres.

The system uses three retaining bands with which the airbag contours are adjusted to limit the volume. The retaining bands are fitted on electrically driven spools. When the airbag is activated, only as much band length is released as the control unit has calculated on the basis of sensor data for the seating position and weight of the occupant.

 

Child Cam: keeping an eye on the kids

With the help of a small camera, drivers will in future be able to keep children travelling in the rear under control without taking their eyes off the road.

"Mum, Vanessa keeps pulling my hair!" "John's seat belt isn't properly fastened." - Parents know that when the kids are on board, there is usually no shortage of action on the rear seats. But if the driver looks back to see what is going on, there is a risk of an accident. Accordingly Mercedes safety experts have developed "Child Cam", a simple camera system that enables the kids to be observed without taking one's eyes off the road.

A small camera is mounted on the roof lining behind the front seats. If required its images can be transferred to the dashboard display - not in video form, but as sequences of stills to avoid distraction. The camera position provides a slight bird's-eye view, which allows children in rear-facing child seats to be
observed more easily.

"Child Cam" also shows rear areas that are not easy for the driver to observe, e.g. the seat directly behind. And in the case of an estate car, SUV or van, it is also possible to monitor the luggage compartment. This is very useful if domestic pets are on board, for example.

 

Interseat Protection: don't get too close to me

Danger not only comes from outside during an accident. In unfortunate cases even passengers wearing their seat belts can come into contact and injure each other. Interseat Protection in both seat rows helps to prevent this.

Mercedes safety specialists are presenting two proposed solutions in one with Interseat Protection: a protective system for the driver/front passenger and one for the rear-seat passengers. As a common feature of both, the occupants are physically separated from each other if the PRE-SAFE® system registers an accident. Within fractions of a second, a lattice-like airbag support structure extends from between the front seats to keep the driver and front passenger apart. A seat-mounted solution like this has the advantage that the protective barrier adapts itself to the position of the front seats.

The seat position does not need to be taken into account in the rear, therefore a protective pad located above the centre armrest is used when an accident is detected. This pad helps to prevent the two passengers in the rear from impacting each other. When the pad is at rest it can be activated as part of PRE-SAFE®. Within fractions of a second, the seat divider emerges and the two head supports are deployed.

Mercedes accident research has shown that during a side impact, and also during a rollover, the heads of the passengers move along different paths: around 50 milliseconds after the accident, the head of the person facing the impact changes the direction of its evasive movement towards the centre of the vehicle - impelled by the sidebag and head airbag. A second important finding from these analyses is that a collision between the passengers can only be avoided if the torso is supported. The protective pad of the Interseat Protection system is dimensioned accordingly.

In normal cases the protective pad in the rear is more of an innovative comfort feature: the pad is designed to be extended by the passengers at the touch of a button, when it can be used as a head and shoulder support for a comfortable sleeping position. It would also be conceivable to use the space for stowage or a cooler box, or an entertainment console.

 

Hybrid Battery Shield: seven-stage safety system

A drive train with hybrid technology lowers fuel consumption and CO2 emissions. At the same time this introduces high-voltage electricity and sophisticated battery systems into passenger car engineering, however. Thanks to their long experience with fuel cell technology, Mercedes development engineers are extremely well prepared for the new challenges this presents. A comprehensive, seven-stage safety concept is the result.

The challenge lay in not only complying with all the worldwide and in-house crash test requirements, but also in ensuring the greatest possible safety for the electrical components. This safety system already applies in production, includes workshop personnel during servicing and maintenance, and also takes the emergency services into account when passengers need to be recovered following an accident. The seven-stage concept in detail:

  1. In the first stage all the wiring is colour-coded to eliminate confusion, and all components are marked with safety instructions. This makes the regular technical inspections easier to carry out.
  2. The second stage comprises comprehensive contact protection for the entire system by means of generous insulation and newly developed, dedicated connectors.
  3. As part of the third stage, the lithium-ion battery has been given a whole package of carefully coordinated safety measures. This innovative battery is accommodated in a high-strength steel housing, and also secured in place. Bedding the battery cells in a special gel effectively dampens any jolts and knocks. There is also a blow-off vent with a rupture disc and a separate cooling circuit. An internal electronic controller continuously monitors the safety requirements and immediately signals any malfunctions.
  4. The fourth stage of the safety concept includes separation of the battery terminals, individual safety-wiring for all high-voltage components and continuous monitoring by multiple interlock switches. This means that all high-voltage components are connected by an electric loop. In the event of a malfunction the high-voltage system is automatically switched off.
  5. Active discharging of the high-voltage system as soon as the ignition is switched to "Off", or in the event of a malfunction, is part of the fifth stage.
  6. During an accident, the high-voltage system is completely switched off within fractions of a second.
  7. As the seventh and last stage, the system is continuously monitored for short circuits.

 

"Still many more ideas for more safety"

Interview with Prof. Dr. Ing. Rodolfo Schöneburg, Head of Safety Development, Mercedes-Benz Cars.

Prof. Dr. Ing. Rodolfo Schöneburg was born on 30 October 1959, studied aerospace engineering and obtained his doctorate at the Technical University of Berlin. He holds an honorary professorship at the College of Technologyand Business Economics (HTW) in Dresden. He has been active as the head of the centre for safety/vehicle functions at Mercedes-Benz since April 1999. It was under his aegis that the preventive occupant protection system PRE-SAFE®entered series production in 2002, with which Mercedes-Benz started a new era in vehicle safety. Here are some of Prof. Schöneburg's comments on the ESF 2009 experimental safety vehicle.

Question: Prof. Schöneburg, during the period from 1971 to 1974 Mercedes-Benz presented four Experimental Safety Vehicles (ESFs) to the public. Then there was silence. Why?

Prof. Schöneburg: At the end of the 60s, vehicle safety suddenly became a focus of public attention. In 1969 the Mercedes-Benz Safety Centerwas founded in Sindelfingen. Numerous developments were initiated, ranging from active safety with ABS and ESP® to fundamental improvements in vehicle structures and innovative restraint systems such as the airbag. All of these were tested and presented in our ESFs, and from the mid-70s more and more of these innovations reached series production maturity. Accordingly they were subsequently presented with the launch of new series production models.

Question: So why are you presenting another research vehicle now, the ESF 2009?

Prof. Schöneburg: Both in-house and externally, the large number of safety features that we already have in our series production cars has created the impression that we do not have much more to offer in this respect. This impression is quite wrong - we have a wealth of ideas on how safety might be improved still further. Some of these can be realised within a relatively short time, for example PRE-SAFE® for rear-end collisions. Other concepts like the inflatable metal sections in PRE-SAFE Structure lie well in the future. And with Interactive Vehicle Communication we are only just starting to develop a completely new field. The ESF 2009 comprehensively offers up all these perspectives. Moreover, our intention was to send out certain signals for the ESV Conference, which is being held in Stuttgart for the first time since 1971.

Question: What is particularly special about the ESF 2009?

Prof. Schöneburg: As with the ESFs of the 1970s, this is a comprehensive embodiment of our safety philosophy. The primary aim is to prevent accidents in the first place. Where this is not possible, the aim is to mitigate their effects. Moreover, we want to approach both of these goals without increasing the vehicle's weight, restricting its practicality or compromising the autonomy of the driver. He or she bears the final responsibility - and the car should provide support in the process.

Question: What new ideas have been incorporated into the ESF 2009 to prevent accidents where possible?

Prof. Schöneburg: These start with the concept of "seeing and being seen". The LED headlamps of the ESF2009 not only illuminate the road further and more efficiently, but also ensure that other detected road users are not dazzled in the process. The Spotlight function is something quite new: it precisely pinpoints obstacles or objects that have been recognised by the infrared Nightvision camera. Thanks to new reflective strips on the sides, which leave the body design unaffected during daytime, the ESF 2009 is also much more easily visible to other road users in the dark. One technology which we think has tremendous potential for the next few years and decades is car-to-car communication. This makes it possible to warn drivers of hazards on their route as the situation requires.

Question: In addition to highly developed restraint systems, Mercedes cars with PRE-SAFE ® have a preventive safety system that can recognise an impending accident and mitigate its effects with numerous actions right up to automatic emergency braking. Is it still possible to make significant improvements to this already high standard?

Prof. Schöneburg: Yes indeed. The basis for PRE-SAFE®is a network of onboard sensors and systems, and this is where we still have plenty of ideas for further developments. Take side impacts as an example: with the help of air chambers in the seats, it would be possible to move the passengers away from the danger zone to some extent. We have already spoken about improvements where rear-end collisions are concerned. And the Braking Bag is a completely new approach to scrubbing off energy before an impact occurs.

Question: At first glance this is a crazy idea - using an airbag under the car to force a high-friction coating against the road surface as an auxiliary brake...

Prof. Schöneburg: ...certainly unusual, but by no means crazy. Initial trials of the principle have shown this idea to have considerable potential. In the next few years we intend to research and develop this potential further.

We look forward to the results, and thank you for this interview.

 

The history of Mercedes-Benz Experimental Safety Vehicles (ESFs): milestones in safety development

In the early 1970s, alone on the occasion of the ESV programme Mercedes-Benz built over 30 experimental vehicles for research on future automotive safety systems. These prepared the ground for numerous innovations, some of which only reached series production maturity years later. They include ABS, belt tensioners and belt force limiters, airbag and side impact protection.

In the 1960s it became impossible to ignore a negative aspect of mass motorisation: more and more people were being killed on the roads. In 1968 the US Department of Transport therefore started a programme for the development of Experimental Safety Vehicles (ESVs), and initiated the international "Technical Conference on the Enhanced Safety of Vehicles". In 1970 the first requirements to be met by ESVs were defined. These included an extremely demanding frontal and rear-end impact against a rigid barrier at 80 km/h, and a side impact against a mast at 20 km/h. The test vehicles also had to withstand minor accidents at 16 km/h without lasting deformations at the front and rear. It was also believed that American consumers would not accept having to actively put on and fasten a seat belt, therefore automatic belt systems were envisaged which would envelop the front occupants when the doors were closed.

The American government also issued an invitation to foreign countries to take part in this safety research. In 1970 this gave rise to the still active European Enhanced Vehicle Safety Commitee (EEVC).

At Mercedes-Benz the challenge of designing vehicles with even more safety was taken up with great enthusiasm. After all, the company was already able to look back on more than 20 years of continual safety research at the time. And about ten years previously, in 1959, the fundamental basis for all future safety developments had already entered series production at Daimler-Benz: the safety bodyshell with impact energy absorbing crumple zones at the front and rear, and a rigid passenger compartment between them.

From spring 1971 the ESV project went full-steam ahead in the separate safety research department founded at Mercedes-Benz in Sindelfingen in 1969. All in all, 35 vehicles were built and tested over the four following years. The first test took place on 12 March 1971 with a W 114 from series production, i.e. the medium-class series at the time. The car was subjected to a frontal impact on a rigid wall at 80 km/h. The tests also included frontal and rear-end collisions, lateral collisions with masts and other vehicles, and also drop tests from a height of 0.5 metres.

The development focus was not only on occupant protection during an accident by means of correspondingly improved vehicle structures and innovative restraint systems, however. Even almost forty years ago, the still valid, comprehensive approach to safety always taken by Mercedes-Benz applied, as an extract from the description of the ESF 13 first presented in May 1972 shows.

This already refers to still current concepts such as driver-fitness safety through seating comfort, climate control and non-intrusive vibration/noise characteristics. Where perceptual safety is concerned, the ESF 13 featured pneumatic beam range control, a headlamp wash/wipe system, a tail light monitoring system in the cockpit, a rear wiper and a safety paint finish with a light colour and contrasting strips. External safety features for the protection of pedestrians and two-wheeled road users included foam-covered front and rear bumpers, rubber drainage channels and rounded door handles. Fire safety was also taken into account: the fuel tank was above the rear axle, well away from the exhaust system. The fuel pump was if necessary deactivated by a mechanism that depended on the engine oil pressure, a valve system prevented any spillage of fuel if the car stood at an unusual angle, the materials used in the interior were fire-retardant and a fire extinguisher was conveniently mounted on the lower front of the driver's seat.

Mercedes-Benz presented the following four ESFs to the public:

ESF 5: developed on the basis of the W 114 ("Strich Acht") series and presented at the 2nd International ESV Conference from 26 to 29 October 1971 in Sindelfingen

ESF 13: Stylistically revised variant of the ESF 5, presented at the 3rd International ESV Conference from 30 May to 2 June1972 in Washington (USA)

ESF 22: Based on the W 116 series (1971 S-Class) and presented at the 4th International ESV Conference from 13 to 16 March 1973 in Kyoto (Japan)

ESF 24: Modified S-Class (W 116) presented at the 5th International ESV Conference from 4 to 7 June 1974 in London (Great Britain)

The foundations for the current safety level of cars bearing the Mercedes star had therefore been laid. Extract from the summary test report (1975): "The ESF 24 can be regarded as the completion of the project, as this vehicle represents the best possible compromise between the original ESV requirements and our current series production cars."

At Mercedes-Benz safety was included in the development specifications for new cars as a matter of course decades before the ESVprogramme, and in rapid succession the ideas first realised as part of the ESFproject entered series production as well.

The milestones included:

1978: premiere of the ABS as an option for the S-Class
1981: driver airbag and belt tensioneravailable in the S-Class
1995: belt force limiters and sidebags enter series productionof the E-Class

 

This is how the ESF 2009 was created: 13 innovations, 1 team

The ESF 2009 is the first Experimental Safety Vehicle Mercedes-Benz has built since 1974. Like its historic predecessors, it attractively combines trailblazing innovations in the field of safety and makes the progress achieved visible. Integrating all the ideas and implementing them for a clear appreciation was an extraordinary challenge for the team in the test vehicle workshops.

The go-ahead for the ESF was given in October 2008, and the decision was received with great enthusiasm in the test workshop: "Making safety visible - I was quickly able to assemble a highly qualified team for this interesting project", says Axel Wittig, the team leader for the entire workshop facility. "The complexity of this assignment was a welcome challenge, as we not only had to integrate the numerous innovations into an S 400 HYBRID, but also make them fully functioning in demonstration mode and provide a look behind the technical scenes by incorporating eight inspection windows in the bonnet, bumpers and doors."

The core workshop team for the ESF 2009, headed by coordinator and facilitator Hans Peter Hiller, consisted of three model-builders and two electricians. The team was supported by Jürgen Arnold, who took care of the electrical engineering, and designer Matthias Rissmann, who e.g. prepared the body apertures for the inspection windows. It was only possible to keep to the ambitious time-plan because countless internal (from the upholstery specialists in Design to production engineering) and external suppliers gave rapid and unbureaucratic assistance. "The great enthusiasm for the core Mercedes expertise of safety could be felt at all times", project manager Michael Fehring remembers: "The 'Daimler spirit' ensured rapid decisions without time-consuming consultation processes." Sheer fascination for technology also played an important part. The chance to take a look into a radar sensor, which is normally only supplied as a 'black box' but was in this case integrated into the front bumper in a cutaway state, attracted many an engineer who was not involved in the project into the workshop bay for the ESF 2009.

The complexity of this project, which involved the integration of 13 safety innovations into the hybrid version of the S-Class that only existed as a prototype when the work started, is already shown by the fact that a completely new wiring harness had to be designed and produced. At the heart of the demonstration technology is a divided compressed air tank in the boot, with a compressor and external power supply, which provides the airbags and the air chambers for PRE-SAFE Pulse and Interseat Protection with air. The finishing touch for the ESF 2009 is a central remote control system for all the functioning demonstrations.

The result of all this work was two experimental vehicles in the special ESF paint finish, which includes black-painted chrome trim and reflective strips on the door seals and tyres: the actual ESF 2009 and its externally identical brother, which can be used for driving and photographic purposes.