The new Mercedes-Benz GL-Class: Visibility and safety - Complete awareness
In conjunction with the assistance systems' "electronic crumple zones" and the intelligent bodywork design, the occupant protection systems provide the highest-possible degree of safety. An overview of the latest-generation restraint systems:
- Two-stage airbags for driver and front passenger
- Driver kneebag
- Sidebags for driver and front passenger (combined thorax airbag/pelvisbag)
- Sidebags available for the central row of seats upon request
- Windowbags across three rows of seats from A- through to D-pillar
- 3-point seat belts for all seven seats
- ISOFIX child seat anchorages on the left and right in the central and the rear row of seats
- Belt-height adjustment for driver and front passenger
- Belt-status indicator for rear-compartment passengers in instrument cluster
- ACSR automatic child seat recognition system (optional) with front-passenger airbag deactivation when using Mercedes-Benz child seats
Passenger compartment encloses occupants like a protective cocoon
In a frontal crash, the front-end assembly can absorb impact energy and thus attenuate the peak loads on the occupants. The front-end structure essentially comprises two straight front longitudinal members, a second upper longitudinal-member plane and a subframe that supports the drive unit, connects the structure's two halves and deforms when subjected to high frontal impact loads. The lateral connections in the front-end activate the side opposite of the impact point in offset frontal impacts. The long front-end, short V-engines and the articulated shaft with its deformation element also contribute to the front-end assembly's deformation potential. In the event of major deformations, the wheels are supported against the strong bulkhead. The bulkhead itself is reinforced by an exterior cross member resting against the A-pillars above the pedal floor.
The passenger compartment's strength is tailored to the deformation resistance of the front-end assembly and envelops the occupants on all seven seats like a protective cocoon. The outstanding rigidity and strength result in part from the floor system with its separate transmission tunnel and longitudinal members integrated into the sidewall that, together with cross members set onto the floor, forms a stable supporting structure. The high-strength sidewall assembly comprises the body pillars, the lateral roof frame and the lateral longitudinal members. The sidewall assembly's outer shell is formed by the outer panelling. The inner shells are partially made up of several components with large-surface nodes between the pillars, roof frame and lateral longitudinal members.
The dual-shell A-pillar with its maximum-strength interior reinforcement is stabilised along the transverse line by the front roof frame and various cross members. The latter are located in the area beneath the windscreen, above the pedal floor and below the dashboard. An effective protection concept has also been implemented to account for rear impacts. Long deformation paths thanks to box-shaped rear longitudinal members, the location of the fuel tank ahead of
the rear axle and of the filler neck above the rear axle provide a high energy absorption capacity in the event of rear-end collisions.
The GL-Class also provides the greatest possible protection for more vulnerable traffic participants such as pedestrians and cyclists. Besides the yielding areas of the front-end, the folding exterior mirrors and the smooth contours, the risk of suffering injury from impact with the vehicle has been reduced through modifying the bonnet and increasing the distance to the components in the engine compartment. In addition, the active bonnet is a standard feature. It has the potential to reduce the severity of any injuries suffered by an impacting pedestrian or cyclist and further increases the deformation space. To optimise trigger criteria detection, acceleration sensors have been additionally integrated into the front bumper.
The GL-Class easily meets new crash requirements
In developing the GL-Class, the test specifications and criteria for accident testing applied in-house went far beyond those required by law. The GL was therefore perfectly able to fulfil even the most stringent requirements of the most important international test institutions:
- Frontal collisions: New full-width front impact in accordance with US-NCAP (US New Car Assessment Program)
- Side impact: New mast impact in accordance with Euro-NCAP (European New Car Assessment Program)
- New side impact in accordance with US-NCAP
- Roof strength: New roof strength test in accordance with IIHS (Insurance Institute for Highway Safety)
- Pedestrian protection: Impact testing according to Euro-NCAP
Thanks to its comprehensive protection concept, the GL-Class has the potential to achieve excellent marks in all international crash ratings.
Assistance systems act as "electronic crumple zone"
Further optimisation of driving and condition safety in the new GL-Class is provided primarily by the numerous assistance systems' capacity to pre-empt accidents by acting as an "electronic crumple zone".
In addition to the driving dynamics control systems ESP® and 4ETS, the GL-Class comes as standard with the electronic brake control system ADAPTIVE BRAKE that improves traction, driving safety and operating comfort. The ADAPTIVE BRAKE electronic brake control system comprises the basic anti-lock braking (ABS) function and anti-slip regulation (ASR) as well as GMR active yaw control. ABS and ASR primarily monitor and affect longitudinal dynamics while GMR controls lateral driving dynamics. Where critical driving conditions are detected, and where physics will allow, selective wheel braking and engine torque adjustments are applied in order to maintain or recover traction and driving stability. In addition, ADAPTIVE BRAKE communicates with all other assistance systems and further comprises the following functions as standard:
- BAS Brake Assist
- Trailer stabilisation
- DSR Downhill Speed Regulation
- Cruise control
- Tyre pressure loss warning
- HOLD, hill start assist, brake priming and brake drying
With the GL-Class, COLLISION PREVENTION ASSIST premieres in the SUV segment. Also featured at no extra charge are the fatigue detection system ATTENTION ASSIST and a steering assistant. Optional systems such as the distance and cruise control system DISTRONIC PLUS, BAS PLUS Brake Assist or PRE-SAFE® BRAKE featuring autonomous braking are also available to increase safety in the event of hazards not recognised by the driver. The available options also include Active Lane Keeping Assist, Active Blind Spot Assist and Speed Limit Assist.
Radar-assisted COLLISION PREVENTION ASSIST
Almost fifty percent of all rear-end collisions can be prevented, or their severity reduced, with the aid of radar-based safety systems such as collision warnings and adaptive brake assistants. This has been shown by the detailed analyses performed by Mercedes-Benz accident research. It is here that experience with the Mercedes-Benz innovations DISTRONIC PLUS and BAS PLUS pay off. With the GL-Class, an SUV will now feature such a system for the first time: COLLISION PREVENTION ASSIST*. Unlike conventional systems, this new brake assistant is not merely a purely urban-driving system designed to minimise trifling damage. The innovative solution aims instead to provide protection against typical rear-end collisions in all traffic situations. The company expects the collision warning system to have a significant and positive effect on accident occurrence statistics. Test results underscore this assessment: in simulator tests with drivers, COLLISION PREVENTION ASSIST was shown to reduce the accident rate in three typical accident scenarios from forty-four to eleven percent.
* Country-specific standard equipment
COLLISION PREVENTION ASSIST issues visual and audible warnings when detecting obstacles to drivers who may be distracted and prepares the brake assistant to apply the brakes as precisely as possible. This brake application is then triggered as soon as the driver exerts pressure on the brake pedal. The system also meets the fundamental "Forward Collision Warning" requirements of the US National Highway Traffic Safety Administration (NHTSA) and is capable of:
- Identifying the distance to the vehicle in front as too low in a speed range from 30 to 250 km/h.
- Detecting a reduction in distance. Where there is a risk of collision, the driver receives a visual and audible warning.
- Detecting stationary obstacles along the path of motion and issuing corresponding warnings.
- Identifying specific driving situations, such as driving in queued traffic, and adapting the trigger threshold for warnings and the adaptive brake assistant accordingly.
- In the event of a collision risk, calculating the precise brake force ideally required to avoid impact and make the best-possible use of the remaining distance. This inherently increases a following driver's chances of himself avoiding a rear-end impact.
- Readjusting the brake pressure when the situation changes – if the vehicle in front accelerates, brake pressure is returned to the degree requested by the driver; if the distance to vehicles driving or stopping ahead drops, brake pressure is increased even further.
- Activating, where necessary, preventive safety systems such as PRE-SAFE® or belt tensioners.
In the extreme range of driving physics, drivers are also aided substantially by a number of systems, including the steering assistant which, for instance, helps the driver by applying steering torque to the steering wheel when the vehicle oversteers. An innovation and a highlight in the new GL is the standard Crosswind Assist, which uses targeted brake application to aid the driver when driving in high transverse wind force conditions, thus increasing the perception of safety and comfort.
Stability even in sudden crosswind gusts
The driving situation is well-known: when driving on high-quality country roads or dead straight stretches of motorway, the occupants suddenly perceive a forceful blow from the side, for instance when overtaking a truck, driving onto a bridge or at the end of lateral constructions such as noise abatement walls. The vehicle has been hit by a crosswind gust. Drivers of the new GL need not fear such gusts of crosswind as the driving dynamics control systems reliably compensate for these meteorological assaults and keep the vehicle firmly on course. Depending on the direction and intensity of the crosswind, the control systems apply corresponding brake pressure to the wheels and compensate, or at least substantially mitigate, the wind's effects on the vehicle. The intervention manoeuvre is handled by ADAPTIVE BRAKE. The required information is supplied by the sensors of the Electronic Stability Program ESP®, the AIRMATIC ADS air suspension and the electromechanical steering.
If the system identifies a necessity to intervene, the driver is assisted through brake application on the front and rear wheel on the upwind side. This intervention results in a steering effect that reduces the impact of the crosswind. Crosswind Assist is active when driving straight ahead or through light bends at a speed of 80 km/h or more. The driver always remains in control: in the case of substantial and/or rapid steering corrections, Crosswind Assist is automatically suspended. The system filters minor crosswinds and only becomes active at a certain threshold. Continuous, constant crosswinds are also ignored. Research has shown that the latter driving situation affects comfort and perceived safety far less and is intuitively compensated for by drivers.
Back on track with the steering assistant
The standard steering assistant becomes active whenever the assistance systems identify unstable driving conditions that can be eliminated through simple steering actions. The system determines a steering torque corresponding to the driving condition and applies this torque through the electric power steering. When oversteering – the vehicle's rear creeping toward the outer edge of the corner – the steering assistant requests the driver to countersteer via the steering wheel until the vehicle has once again stabilised. The second primary feature is assistance when braking on a surface that displays different friction coefficients on the right and left of the vehicle, as is the case for example on partially iced-up carriageways in winter. The steering assistant notifies the driver of the direction in which the steering wheel should be turned in order to neutralise the yawing impulse. Even if the driver ignores the steering assistant's recommendations, ample reserves remain to stabilise the vehicle in the form of the driving dynamics systems such as ADAPTIVE BRAKE, ESP® or 4ETS. The steering assistant is always available to provide the driver with recommendations, but never takes over.
Even after a crash: occupant protection
After a more substantial crash, the hazard warning lights are switched on automatically in order to warn the surrounding traffic. At the same time, the door locks are automatically disengaged in order to facilitate the best-possible access to the vehicle occupants for emergency services. Thanks to the partial opening of the side windows, the interior is more efficiently ventilated after restraint systems have triggered.
Where a collision is detected, the central control unit shuts off the fuel system. After determining the cylinders' positions, the engine management opens the injectors on cylinders not in compression stroke and relieves the fuel high-pressure area by releasing the remaining fuel directly into the combustion chambers. This reduces the risk of fuel escaping. As a further measure to prevent fuel from escaping, the relevant points feature cut-proof fuel lines and this also increases safety in the event of a collision.
If COMAND Online is chosen for the new GL-Class, the automatic Mercedes-Benz emergency call is included as standard. In the event of a serious accident, emergency services are notified automatically and within minutes are furnished with extensive information on the precise accident location or the respective vehicle model. The operating principle: if airbags or belt tensioners are triggered in a crash and COMAND Online is connected to a mobile phone, the system transmits the vehicle's precise GPS location and its chassis number (VIN) to both the emergency services and the Bosch Communication Center's service control room by text message. The location data is also transmitted by DTMF (dual-tone multi-frequency). Even if the occupants are unconscious or do not know their precise location, for example when on holiday, the emergency services called by the Communication Center can be informed precisely and rapidly.
The vehicle also quickly establishes a voice connection to the Bosch Communication Center. The language used does not correspond to the respective country's language but to the language set in COMAND Online by the driver. Emergency calls can also be placed manually as the "Mercedes-Benz emergency call" entry is always located at the very top of the phone book list. With the launch of the GL-Class, the emergency call will be able to access the phone network in nine European countries: Germany, France, Italy, Spain, the United Kingdom, Austria, Belgium, the Netherlands and Switzerland. By late 2012, nineteen further countries will be added. Apart from any possibly applicable mobile phone rates, a Mercedes-Benz customer will incur no costs for using the Mercedes-Benz emergency call service.
The GL sees all: 360° camera, NightView Assist PLUS and off-road lights
Together with the compact character GLK, the GL-Class will be available for the first time with the 360° camera. The 360° camera is always combined with PARKTRONIC and is supplied with imaging information by a total of four cameras located respectively in the radiator frame, in the tailgate above the number plate and in the two exterior mirrors. The system uses the imaging information to compile various views, among them a depiction of the vehicle and its surroundings from a bird's-eye perspective. Occupants view the picture in real time in the central COMAND display. This allows the areas behind, in front and to the side of the vehicle to be observed and can thus prevent collisions in a multitude of different manoeuvres both on- and off-road. Supplemented dynamic guiding lines assist orientation. For example, the 360° camera indicates the vehicle's turning area in accordance with the steering-wheel angle.
The 360° camera is automatically activated when reverse gear is engaged or when selected directly in COMAND. The camera images in the display switch depending on the transmission position selected: when reverse is engaged, the display automatically shows the image relayed by the rear camera. Bird's-eye view or the individual images can be selected by the driver by means of the COMAND controller at any time. Specifically, the 360° camera can provide assistance to the driver through the following functions:
- Virtual bird's-eye view shows the GL from above and the three metres ahead and behind as well as 2.5 metres of the area next to the vehicle.
- Depiction of perspectives not actually physically attainable. Example: when manoeuvring inside a multi-story car park with low ceilings, the GL and its surroundings are depicted from a bird's-eye view more than three metres above the vehicle, even if the ceiling is only a few centimetres above the vehicle.
- Visualisation of vehicle sides and their surroundings to prevent contact damage, e.g. of the exterior mirrors or rims.
- Visualisation of obstacles outside of the field of vision below the vehicle's beltline.
- Visualisation of crossing traffic when manoeuvring out of tight parking spaces or departing from driveways.
- Visualisation of pedestrians on the pavement when manoeuvring out of tight parking spaces or departing from driveways.
- Assistance when driving off-road in difficult and confusing terrain.
- The GL-Class is always depicted in the COMAND display in the vehicle's actual colour.
For the first time, the cameras in the GL now feature high-performance digital CMOS image sensors (Complementary Metal Oxide Semiconductor). Each camera processes images at a resolution of one megapixel and covers a 180-degree field of vision. The views compiled from the four individual images by the system and shown in the COMAND display are of impressively high quality. The virtual bird's-eye view is almost entirely distortion-free. Unlike the familiar systems, which utilise black bars to separate the individual images, the 360° camera displays the total image homogeneously without transitory elements. In addition, the 360° camera adapts to the various vehicle heights, for example if the maximum-possible ground clearance of 600 millimetres that comes with the ON&OFFROAD package has been chosen. The driver is also kept aware of the surroundings when manoeuvring at night. At speeds of up to 10 km/h with the headlamps switched on, activating the 360° camera also activates the surround lighting. The 360° camera also offers another special feature that prevents occlusion of the rear camera through soiling, for example during long journeys through muddy terrain or when driving on wet, salt-strewn motorways in winter. A flap covers the camera and provides reliable protection from soiling. The flap opens automatically when the 360° camera is activated.
NightView Assist PLUS turns night into day. The optionally available assistance system utilises two infrared headlamps. The emitted long-wave light is invisible to the human eye and covers the carriageway ahead of the GL-Class at a range corresponding to main beam. The camera located in the windscreen in the area of the rear-view mirror records the infrared image and, after processing by the control unit, relays it to the COMAND display. Here, the scene is depicted in high-definition grey-scales. Detected pedestrians are additionally highlighted by "photo corners" to make them even more easily visible. The system is available at full performance as of a speed of 10 km/h.
When driving in difficult terrain at low speeds, it is useful to illuminate the area ahead of the vehicle as brightly and as widely as possible. The new GL, if equipped with the ON&OFFROAD package in conjunction with the Intelligent Light System, will feature special off-road lights that provide precisely such illumination. If the driver activates either the OFFROAD 1 or the OFFROAD 2 driving program while the headlamps are switched on, the off-road lights are automatically activated as well. The bi-xenon headlamp modules are swivelled outward through six degrees, the xenon burners output is increased by 3 watts and the light cone is set to symmetrical. In addition, the LED cornering lights on both sides are switched on permanently, while both the dynamic cornering light function and the headlamp beam adjustment are deactivated. These settings combine to give a wider and brighter illumination of the area ahead of the vehicle than is provided by the Intelligent Light System, configured for optimal illumination when driving on roads. Orientation during off-road driving is substantially improved and any obstacles can be seen earlier. The off-road lights are active at speeds up to 50 km/h. When the driver exceeds this threshold, the Intelligent Light System automatically resets the lighting functions to optimum road operation.
As 40% of all serious accidents occur at night, the temperature of the xenon burners used by the Intelligent Light System has been raised to 5,000 Kelvin to further increase safety. This results in an illumination very similar to daylight, which improves comfort and relieves the strain on the driver.
Braving the gap: Active Parking Assist
The new-generation Active Parking Assist utilises ultrasonic sensors at a speed of up to 35 km/h to identify potential parking spaces along the road on the side the vehicle is travelling on, or on both sides in one-way streets. Suitable parking spaces are indicated in the central display. The driver can then start Active Parking Assist by pressing a button on the multifunction steering wheel. The system calculates a suitable trajectory from the vehicle's current position. The driver then only needs to accelerate or brake – the required steering motions are completed fully automatically by the system. Departing from parking spaces works the same way.
Active Parking Assist comprises six ultrasonic sensors in the front bumper and four in the rear bumper. The ultrasonic sensors on the corners of the front bumper have a greater range than the other sensors in order to facilitate reliable detection of parking spaces when driving past them.
Get your bearings: parking and manoeuvring aids through the years
In the early days of the automobile at the beginning of the last century, car manufacturers were already thinking about ways to aid drivers in keeping an overview when manoeuvring their vehicles. First efforts using a variety of marker rods on the outer ends of the bumpers only caught on with commercial vehicles. In 1959, with the Mercedes-Benz passenger car models referred to as "tailfins", the first real attempt was made to integrate orientation aids into the general design concept of a car. The tailfins on Mercedes-Benz medium-sized and premium-class saloons, officially termed marker bars, facilitated excellent estimation of the body's position, in particular when glancing obliquely over one's shoulder such as one might do when parking. For a long time, the more or less substantial bulges on the rear wings remained the tool of choice.
This did not change until the early 1990s and the new model series 140 S-Class. At up to 5.20 metres in length, the premium-class car offered its occupants superior space in the interior but also required aids to make the rear end of the body visible when manoeuvring. The solution: extendable, chrome-plated marker bars on the rear wings that were pneumatically lifted when reverse gear was engaged, thus providing a visualisation of the S-Class's rear end. Though effective, the mini-aerial solution did not correspond to the technology levels associated with Mercedes-Benz's top-range model over the long term.
Consequently, the developers went to work and, in 1995, presented the revolutionary PARKTRONIC system. The new system adopted a natural model by adapting the ultrasound orientation system familiar from bats and combining it with highly sophisticated electronics. The distance to obstacles was indicated by coloured LCD displays in the dashboard. If the driver ignored the displays, closer approaches were accompanied first by a clearly audible intermittent tone and then by a continuous tone warning of imminent collision.
Parking Assist, available for the S-Class as of 2005, provided even greater precision by relying not on ultrasound like PARKTRONIC but on the radar sensors of the DISTRONIC and Brake Assist PLUS systems. The advantage compared to the bat principle: the territory monitored around the vehicle was significantly larger. Here too, the driver was notified of his territorial behaviour by way of the typical beeping. Visually, however, a colour display in the instrument cluster now provided substantially greater details on the manoeuvring course. In addition, engaging reverse gear also automatically activated an additional display in the rear roof lining.
In the same year, the first reversing camera premiered in the S-Class, available then in conjunction with PARKTRONIC which was still on offer. The camera eyed the surroundings from the boot lid above the number plate, relaying its image to the COMAND display once reverse gear was engaged. The system's electronic director also calculated the optimum path into the targeted parking space and supplemented the camera's image with corresponding guiding lines.
In 2008, searching for a parking space and parking "manually" became a thing of the past. The then latest generation of the A- and the B-Class were offered to Mercedes-Benz customers for the first time with the option of Active Parking Assist. The electronic passenger kept an eye open for parking spaces on both sides of the vehicle up to a speed of 35 kilometres an hour. Once it found a parking space, the driver was not only happy but also relieved that the following manoeuvring was taken off his hands. An arrow in the instrument cluster indicated the side on which the parking space was located. The driver then needed to engage reverse gear and give the go-ahead by pressing a button on the multifunction steering wheel. The assistant then took over steering while the driver needed only accelerate and brake.
A further step followed only a year later. Parallel to Active Parking Assist, the E-Class was offered with the classic PARKTRONIC including the new parking guidance. This version also looked for parking spaces as described above. However, the driver here needed to handle the steering himself, albeit with the aid of indicators in the instrument cluster display describing the necessary steering manoeuvres. The climax in development of parking and manoeuvring assistants, at least for the present, are the GL-Class's Active Parking Assist with automatic parking and departing function as well as the 360° camera that displays the surroundings to the driver from a variety of perspectives: from the complete panorama of bird's-eye view to the various detailed views that facilitate down-to-the-centimetre precision manoeuvring even in difficult terrain.
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