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®.
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.
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.
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.
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 System: 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 System" 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 System" 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.
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.
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.
Rear seat camera: 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 "Rear
seat camera", 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.
"Rear seat camera" 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.
