With the S500 INTELLIGENT DRIVE and the Future Truck 2025, Mercedes-Benz has already made the vision of autonomous driving become reality. The new research vehicle F015 Luxury in Motion has its world premiere at the Consumer Electronics Show, and provides a concrete example of the visionary ideas the company is developing with regard to autonomous driving of the future. With this self-driving luxury saloon Mercedes-Benz illustrates how the car is growing beyond its role as a mere means of transport and will ultimately become a private retreating space. This new way of travelling gives passengers the freedom to use their valuable time on the road in manifold ways.
Progressing from the self-propelled ("automotive") to the self-reliant ("autonomous") vehicle, Mercedes-Benz as a pioneer goes far beyond the purely technical realisation of automated driving. The company's experts also have to anticipate different outlooks and social trends. People are always at the centre of such considerations. Just as the 1886 Benz Patent Motor Car and its successors revolutionised personal mobility and, as a consequence, society as a whole, the first self-driving cars will also bring about major changes.
"Anyone who focuses solely on the technology has not yet grasped how autonomous driving will change our society. The car is growing beyond its role as a mere means of transport and will ultimately become a mobile living space," explains Dr Dieter Zetsche, Chairman of the Board of Management of Daimler AG and Head of Mercedes-Benz Cars.
Expressive forerunner of a mobility revolution
With the huge amount of space in its lounge-like interior, the Mercedes-Benz F015 Luxury in Motion takes the concepts of comfort and luxury to a new level. Every facet of the vehicle reflects perfectly the Mercedes way of interpreting the terms "modern luxury", emotion and intelligence. This innovative four-seater is a forerunner of a mobility revolution, and this is immediately apparent from its futuristic appearance.
It is obvious that the F015 represents the vision of a brand new vehicle concept just from its unusual proportions (length/width/height: 5220/2018/1524 millimetres), its seamless, monolithic exterior and its large LED light modules at the front and rear. A range of different lighting functions can be provided through these LED fields. At the same time, the vehicle communicates and interacts with the outside world by means of the LED fields. These LED fields show for example, if the F015 is driving autonomously (blue) or is controlled manually (white).
The low-slung front end, smooth and streamlined roof line, flat front windscreen and road-hugging rear end give the F015 Luxury in Motion an extended and decidedly dynamic silhouette. The F015 Luxury in Motion's unusually large wheelbase of 3610 millimetres in combination with its short overhangs clearly show that the design focus was on providing the maximum possible space for the passengers.
A lounge-like interior with an atmosphere of well-being
In the interior of the F015 Luxury in Motion the designers have created a lounge-like space with a feel-good ambience characterised by elegance, quality and lightness. Sensual, flowing transitions and warm, organic materials such as open-pore walnut wood shaped into a three-dimensional veneer, and extremely soft ice white nappa leather contrast with clearly-defined metal and glass surfaces with a cool and technical feel.
The pivotal feature of the innovative interior concept is the variable seating system, with four rotating lounge chairs that allow a face-to-face seat configuration. In order to make getting in and out of the car easier, the electrically powered seats also swing outwards by 30 degrees as soon as the doors are opened. If necessary, the driver and front-seat passenger can also turn their eyes and attention towards the front - a prerequisite for manual driving. To this end the steering wheel extends automatically from the dashboard.
The leather-covered cushions of the lounge chairs are set in curved mounts of highly-polished aluminium. Each seating mount has a contrasting light band of blue LED lights and can also be manually swivelled.
One key aspect of the research vehicle is the continuous exchange of information between vehicle, passengers and the outside world. This is facilitated by six display screens harmoniously integrated into the instrument panel and the rear and side panels, which turn the interior of the F015 Luxury in Motion into a digital arena. Passengers can interact intuitively with the connected vehicle through gestures, eye-tracking or by touching the high-resolution screens. Sensors recognise the passengers' hands and offer them user interfaces within convenient reach that present appropriate operating options for each particular situation. Particle streams on the displays visualise the vehicle's movement.
Revolutionary vehicle structure
The high-strength body of the F015 Luxury in Motion ensures optimum safety and supreme comfort for its passengers. At the same time, the bodyshell's structure provides the ideal basis for the door concept that makes getting in and out especially easy, and for the communication-oriented seating featuring four lounge chairs in a face-to-face arrangement.
New materials and structures were used to develop the highly efficient "Smart Body Structure (SBS)" of the F015. By cleverly combining carbon-fiber-reinforced plastic (CFRP), aluminium and high-strength steels in a way that matches the varying requirements exactly, the lightweight engineering experts were able to make the bodyshell 40 percent lighter compared with today's production vehicles.
Another key element of the body design concept is the innovative saloon-door-style door system featuring rear-hinged rear doors. The front and rear doors can be opened and closed independently of one another. With an opening angle of 90 degrees for all doors, the spacious interior can be easily and comfortably accessed on both sides. B-pillars were not needed. A very sturdy interconnected system with mechanical locking elements ensures exemplary safety standards. These elements securely interlock the front and rear doors when they are closed at the same time as fixing them firmly to the roof frame and side skirts. The resulting composite load path allows an extremely high amount of energy to be absorbed in the event of frontal or side impact, with minimal intrusion into the passenger compartment.
The doors themselves have a crucial role to play in the vehicle's passive safety concept. The crash-responsive beltlines underneath the side windows are vital here. The PRE-SAFE Structure, previously unveiled on the ESF 2009 Experimental Safety Vehicle and now further enhanced, offers maximum safety while taking up minimum space: in a side-on collision, these bodywork elements "inflate" in an instant, just like an airbag, allowing them to absorb as much impact energy as possible.
In addition, the bodyshell of the F015 Luxury in Motion was designed to allow the impact-protected integration of an electric drive system with fuel cell. This is based on the pioneering F-CELL PLUG-IN HYBRID system seen in the F 125! research vehicle from 2011, and combines on-board generation of electricity with an exceptionally powerful and compact high-voltage battery. The pressure tank made from CFRP is designed to store the hydrogen.
The vision: greater quality of life for all city dwellers
As a foundation for creating the F015 Luxury in Motion, experts from all areas of Mercedes-Benz developed a future scenario entitled "City of the Future 2030+", which considered many aspects of mobile living.
The greater the advance of urbanisation, the greater is the desire of the individual to be able to retreat to a private sphere. Autonomous driving will become a given. As drivers are relieved of work and stress in situations in which driving is not enjoyable, the time gained while in their car takes on a whole new quality. Time and space will become the luxury of the future.
New technologies and forms of communication open up numerous new possibilities for interaction, both between the vehicle and its passengers and between the vehicle and other road users.
Autonomous cars also open up new possibilities for urban infrastructure design. Following the example of today's low-emission zones in city centres, special "safety zones" that are only accessible to autonomous vehicles could be created. Urban space would be regained by autonomous vehicles parking themselves on the periphery.
In the shared space of the future, humans and machines share the roads. The "car-friendly city" is transformed increasingly into the "people-friendly city" without any loss of individual freedom. The divide between residential, recreational and traffic areas therefore melts away. The result is superior quality of life for all urban dwellers.
The road to autonomous driving
Even now, vehicles from Mercedes-Benz are capable of detecting many different hazardous situations out on the road and reacting as the situation demands - by means of autonomous braking, for instance. And from the C-Class through to the S-Class, there are already Mercedes-Benz models driving semi-autonomously on public roads today, equipped with features such as DISTRONIC PLUS with Steering Assist and the Stop&Go Pilot semi-autonomous traffic jam vehicle following function. Active Parking Assist with PARKTRONIC allows automated parking with active steering and brake control in both parallel and end-on spaces.
In August 2013, Mercedes-Benz demonstrated to great effect that autonomous driving is possible now. The close-to-production Mercedes-Benz S500 INTELLIGENT DRIVE completed the approximately 100-kilometre journey from Mannheim to Pforzheim fully autonomously, following the route Bertha Benz took in 1888 on the first ever long-distance drive by car.
Mercedes-Benz is setting the pace of development in the area of trucks, too - as the innovator and launcher of intelligent assistance systems. With its Future Truck 2025, the brand presented the world's first truck to feature autonomous driving at the IAA Commercial Vehicles in September 2014. In July 2014, this one-off vehicle, based on the Mercedes-Benz Actros 1845, drove at speeds of up to 80 km/h in realistic traffic situations on a section of the A14 autobahn near Magdeburg.
As a global company, Mercedes-Benz has its sights set on autonomous driving worldwide. In order to factor in the differences in traffic and infrastructure in other markets, the experts also carry out testing in the USA, for example. In mid-September 2014, Mercedes-Benz became one of the first automotive manufacturers to be issued with an official licence by the US state of California for testing self-driving vehicles on public roads there. In addition the company makes use of the USA's largest test facility, the Concord Naval Weapons Station (CNWS).
The design: Expressive forerunner of a mobility revolution
The task of the designers of the Mercedes-Benz F015 Luxury in Motion was to come up with a completely new concept and design for a luxury saloon: Because autonomous driving will create a lot of freedoms of design that can be utilised systematically. The car becomes a precious, private retreat, particularly in urban traffic.
Thus the visionary research vehicle Mercedes-Benz F015 Luxury in Motion was born, a vehicle which raises comfort and luxury to a new level by offering a maximum of space and a lounge character on the inside. Every facet of the F015 Luxury in Motion is the utmost reflection of the Mercedes way of interpreting the terms "modern luxury", emotion and intelligence. This innovative four-seater is a forerunner of a mobility revolution, and this is immediately apparent from its futuristic appearance. Sensuousness and clarity, the core elements of the Mercedes-Benz design philosophy, combine to create a unique, progressive aesthetic appeal.
It is immediately apparent that the F015 represents the vision of a brand new vehicle concept just from its unusual proportions, with a length of 5220 millimetres, width of 2018 millimetres and height of 1524 millimetres, from its seamless, monolithic exterior and from its large LED light modules at the front and rear. A range of different lighting functions can be provided through these extensive LED fields. At the same time, the vehicle communicates and interacts with the outside world by means of these LED fields. The display signals to pedestrians that the F015 has "seen" them. The number plate is replaced by a QR code, making information on the vehicle available to the outside world. This, along with the striking narrow luminescent band on the rear end, makes the vehicle into a "communications centre" on wheels. The monolithic impression is emphasised by the absence of exterior mirrors and the flush-fitting side windows, which have an almost mirror-like appearance thanks to their finely-patterned surface and which blend almost imperceptibly into the flanks of the vehicle body, finished in alubeam.
Dynamic: an extended, flowing silhouette and pronounced body shape
The low-slung front end, smooth and streamlined roof line, flat front windscreen and road-hugging rear end give the F015 Luxury in Motion an extended and decidedly dynamic silhouette. The vehicle body has a pronounced, attractive shape. The generously-sized areas of outer skin fit snugly to the body. The greenhouse is tapered sharply towards the rear, resulting in muscular shoulders which lend an eye-catching contour to the flanks. Together with the powerful-looking side skirt, this gives the sides of the vehicle additional visual structure.
The extremely large 26-inch wheels appear to push down the side skirts, which in turn emphasises the unusually long wheelbase. The alloy wheels are split into five equally-sized, cross-drilled areas of gleaming aluminium.
Expansive: long wheelbase and "saloon doors" that open wide
The unusually long wheelbase of the F015 Luxury in Motion, at 3610 millimetres, is longer by some 245 millimetres than the Mercedes-Maybach S-Class (3365 millimetres). Combined with the short overhangs, it is immediately apparent that the design focus was on providing the maximum possible space for the passengers.
The F015 Luxury in Motion does not have any B-pillars. This fact, together with the wide-opening "saloon doors" that open out the other way to conventional doors, makes getting into and out of the vehicle interior particularly convenient and comfortable. The doors open to a full 90 degrees. This allows a clear view of the generously dimensioned and intelligently laid out interior and ensures problem-free entry. The side impact protection features have been cleverly integrated into the door system.
Open space: a luxury lounge providing the highest levels of comfort
In the interior of the F015 Luxury in Motion the designers have created a lounge-like space with a feel-good ambience characterised by elegance, quality and lightness.
Sensual, flowing transitions and warm, organic materials such as open-pore walnut wood, which has been shaped to a three-dimensional veneer, and extremely soft ice-white nappa leather contrast with clearly-defined metal and glass surfaces with a cool and technical feel. The transitions between organic, metal and synthetic materials have been designed using matrix graphics; and the flowing transitions deliver a new, unparalleled feeling of bounteous space. The light-coloured fine wood used for the floor, for example, flows almost imperceptibly into the cool Plexiglass of the side panels thanks to their unusual surface matrix. The transition between the vehicle floor and the door panels also echoes the outer body shape in a characterful way.
Variable and comfortable: Lounge-like seating system with a vis-Ã -vis configuration
The pivotal feature of the innovative interior concept is the variable seating system, with four rotating lounge chairs that allow a face-to-face seat configuration. This enables the front passengers to turn around and talk directly to the other passengers while on the move - or to focus their attention towards the front as necessary for manual driving. For this, the white leather steering wheel automatically slides out of the instrument panel - also clad in white leather - and offers the driver a choice of driving options. To make getting in and out of the vehicle really comfortable, the electrically-powered seats swivel 30 degrees towards the doors as these are opened.
The cushions of the lounge chairs are upholstered in extremely soft ice-white nappa leather and set in curved mounts of highly-polished aluminium. Each seating mount has a contrasting light band of blue LED lights and can also be manually swivelled. Harmonious touches are provided by the leather head restraints with the Mercedes star strikingly embossed in them, as well as by the seat belts, which are in the same colour as the seat cushions.
Communicative and interactive: the interior as a digital living space
One core theme of the innovative interior concept is a continuous exchange of information between vehicle, passengers and the outside world. Six displays are installed to this end all around, tastefully mounted in the instrument panel and the rear and side walls, making the interior of the F015 Luxury in Motion a digital living space - a perfect symbiosis of the virtual and the real world. Passengers are able to interact intuitively with the connected vehicle by means of gestures or by touching the high-resolution screens. Sensors recognize the passengers' hands and offer them user interfaces within convenient reach that present the suitable operating options for the particular situation. Particle streams on the displays - with brilliant white background graphics - visualise the vehicle's movement and symbolise its intelligence. In addition, individual displays for each seat provide an innovative way for passengers to take in information.
Interaction between passengers and vehicle: Natural and enjoyable operating experience
Communication and interaction between the vehicle, the passengers and the outside world is one of the key ideas behind the Mercedes-Benz F015 Luxury in Motion. The developers have therefore equipped the new research vehicle with an "Extended Sense" system to give it the requisite enhanced perceptual capabilities. Thanks to this high-resolution sensor system, the vehicle keeps a constant eye on its surroundings, is capable of interpreting what it sees and taking action at any time, and relays relevant information to its passengers, depending on the specific driving situation. This converts the F015 into a perfectly dependable partner, while always letting the occupants make the final decision and retain overall control, if they so wish.
The interior of the F015 Luxury in Motion is designed as a "digital activity space" that is fully connected with the outside world thanks to "Extended Sense". Route planning, music selection, images, contacts and many other functions can be displayed on the screens at the sides and in the rear and selected by means of proximity gestures or touch control. A simplified reproduction of the vehicle's surroundings can also be visualised in the displays, with the vehicle's motion depicted in the form of streams of particles. The functions in the front display can be operated by a novel new eye tracking function and by gestures for great ergonomic comfort. The Mercedes-Benz F015 Luxury in Motion thereby gives a preview of how the self-driving car of the future could become a platform for communication and interaction.
User Experience: natural and enjoyable operating experience
The Mercedes-Benz User Experience strategy seeks to wed appealing design with intuitive use. Development of the F015 Luxury in Motion therefore focused on the following fundamental features:
The front display is largely operated by a combination of eye tracking and gesture control. To initiate a control function, the user first looks at the desired element in the main display. As soon as the system has detected the user's intention by means of eye tracking, hand movements are interpreted as control inputs and it becomes possible to interact using gestures. The side displays are operated by means of proximity gestures and touch.
With "Extended Sense", the F015 monitors its surroundings in every direction. Stereo cameras, as well as radar and ultrasonic sensors relay extensive data. High-precision GPS data together with the extremely accurate 3D navigation maps make sure the position can be pinpointed to the exact centimetre. This means the vehicle knows its precise location at all times. Critical traffic situations, such as a potential collision, are detected at an early stage by "Extended Sense", correctly interpreted and averted by taking appropriate action.
The F015 Luxury in Motion identifies its owner or authorised user by means of their smartphone or wearable device. Once the user has been authenticated, the saloon-type doors open automatically and the seats swivel into a position for getting in with the greatest of ease. The opening procedure can also be initiated from outside the vehicle using the mobile device or by touch control. The vehicle only grants access to the interior with the correct digital "key".
Once they have gained entry, the authorised person is also cleared to operate and control the vehicle. Driving-specific functions, such as the desired speed or turning, overtaking and braking, can be governed using a virtual control module if required.
Digital activity space for information and interaction
Displays are installed all around the interior for visualising information and interacting with the vehicle. The neatly integrated screens with crystal clear ultra-HD resolution turn the interior into a digital activity space on wheels. All-round visual information is provided by the wide main screen in the digital dashboard, a Head-up Display in the windscreen area, touch-sensitive screens running the entire width of the door trim panels, as well as a screen positioned between the rear seats at head height and a table with an extending display.
The display units inside the F015 in detail:
The main display in the dashboard shows the driving-related information and operating menus. Functions such as vehicle speed, navigation, climate control, ventilation and the infotainment system volume can be controlled by gestures here. The captured image of the surroundings along the route, including other vehicles, other road users and stationary objects, also appears here, starting off as abstract moving data points that look like particles, in the vehicle's immediate vicinity, then taking the concrete form of a car or pedestrian, for instance.
The side displays in the F015 Luxury in Motion offer its passengers a wealth of options for transporting the outside world into the car and interacting with it. Besides accessing personal address books or playlists of favourite music, the vehicle's route can be displayed as a timeline including points of interest. The lighting and colour mood can also be individually adjusted. The occupants of the F015 furthermore have the option of superimposing various digital natural landscapes on the side displays, including forests, mountains, lakes and coastlines. Other virtual worlds can likewise be projected. The display of the virtual surroundings is always synchronised with the actual vehicle movement, meaning that uphill climbs or downhill descents, for example, are simulated based on the current route profile, thereby allowing the passengers to sense the vehicle's changing motion visually too.
Focus on passenger well-being
Depicting the surroundings in the side displays in the form of flowing particles is also designed to boost passengers' sense of well-being by increasing sensory comfort. To avoid creating a hectic, turbulent impression when visualising the outside world especially, the graphics in the side displays are deliberately simplified. A "manoeuvre flashing" function also forms part of the concept. Front passengers in the rearward-facing lounge position in particular are notified of an upcoming bend or lane change by means of ambient colour signals.
"Pick me Up" app-based service
Thanks to full connectivity at all times, the F015 becomes an integral part of the cloud. This means that authorised users are able to access various vehicle information and functions at any time. For instance, the navigation, entertainment or climate control systems can be conveniently programmed from the home PC or, of course, by using a mobile device.
In addition to this, a specially developed app offers further control options even when away from the vehicle using a mobile device. The F015 can therefore be sent off to search for its own parking space, or perhaps to a specific location to collect the user or other occupants. The seating arrangement or desired number of passengers can also be selected in this way.
With the F015 Luxury in Motion, Mercedes-Benz is once again proving itself to be a pioneer in the field of groundbreaking operating experiences that go far beyond the application of familiar consumer electronics or vehicle control concepts. The F015 thereby gives a preview of just how the (self-driving) car of the future could become an emotionally appealing platform for communication and interaction with its own system intelligence.
Interaction between vehicle and environment: Intelligent partner in urban traffic
In the Mercedes-Benz scenario for urban traffic in tomorrow's world, the roads are a shared space for people and vehicles. When designing the F015 Luxury in Motion, therefore, the focus was placed not just on providing optimum support for the passengers in its interior, but also creating added value for the people in its immediate vicinity.
Using the "Extended Sense" sensor system, the F015 permanently monitors its surroundings in a 360-degree radius. Stereo cameras as well as radar and ultrasonic sensors relay extensive data, which is then interpreted with the help of specially developed algorithms. This perceptual and interpretive capability converts the F015 into an intelligent partner for people in urban traffic.
Visual and acoustic signals for greater safety
The F015 Luxury in Motion communicates with its surroundings both visually and acoustically. Large LED displays at the front and rear as well as a laser projection system directed toward the front are responsible for the visual part, while the acoustic communication repertoire includes both sounds and specific spoken instructions.
The displays at the front and rear feature a communication matrix comprising three-dimensional, bar-shaped LED modules, together with two outer blocks made up of large LED bars. Information on the vehicle can be retrieved using the rear display's integral QR code. A slim LED light strip above the rear display is used for visualising driving-specific functions such as braking, indicating and the current driving mode of the F015. When the vehicle is started, the LED blocks in the two communication displays light up in sequence. A special start-up sound signals that it is ready for operation. The F015 then uses the colour of its lights to indicate what driving mode it is currently in - blue stands for autonomous and white for manual. This particular information is communicated at the front by the large outer LED blocks in the grille and at the rear by the slim LED light strip.
The various LED elements that form the communication displays are individually controlled by the system. At the front, both the light distribution and colour are varied to suit the respective situation. Meanwhile, the rear LED display is also capable of displaying short messages for traffic behind, such as "STOP" or "SLOW".
What's more, the high-precision laser projection system allows the F015 Luxury in Motion to project a broad cone of light onto the road in front showing important information. This includes, for example, a virtual zebra crossing indicating to pedestrians on the side of the road that it is safe to cross. And if the F015 brakes with the intention of stopping, a suitable projected display marks the position where it will come to a stop. Other road users can then prepare themselves accordingly.
Communication with pedestrians
Should the F015 detect a pedestrian at the roadside who wishes to cross the road in its immediate vicinity at the front, the vehicle shows an undulating light sequence on the LED communication display indicating that it will wait. If the road is clear, the F015 additionally emits the audible prompt "Please go ahead" to let the pedestrian know that it is safe to cross the road in front of the vehicle.
If there is a pedestrian directly in front of or behind the F015, the car signals this with an undulating tracking light that moves across the display in synchronised fashion in the same direction the pedestrian is walking in. This visual feedback has a similar effect to the eye contact between driver and pedestrian by allowing the F015 to gain the trust of its human fellow road user.
Communication with traffic behind
The F015 communicates actively with the traffic following behind using its LED rear display. If a pedestrian is crossing the road in front of the F015 and therefore out of sight of any vehicles that are following, the F015 displays a sequence of red flashing lights on the rear communication display to warn the road users behind. The additional tracking light indicates the pedestrian's exact position on the LED display. A flashing sequence of lights on the rear display likewise notifies traffic behind when one of the F015 doors is about to be opened.
And when the traffic ahead of the F015 Luxury in Motion starts to slow down, the vehicles behind likewise receive notification. In this case, a lighting sequence runs down the rear LED element from top to bottom. The message "SLOW" then appears for several seconds. If, on the other hand, the traffic in front of the research vehicle should unexpectedly come to a complete stop, the word "STOP" flashes repeatedly.
Human and machine: universal, unequivocal communication needed
The experts at Mercedes-Benz are continuing to work intensively on the devel-opment of a universal and unequivocal means of communication for interaction between human and machine. At the "Robotics" Future Talk in 2014, numerous approaches to this issue were discussed with specialists from a variety of disciplines. A cooperative system needs to be developed to enable social interaction between humans and machine intelligence, especially in dense urban areas.
With the new F015 Luxury in Motion research vehicle, Mercedes-Benz is offering an outlook of how the company could envisage this communication and interaction taking place within the scope of autonomous mobility.
The body concept: Revolutionary vehicle structure
The high-strength body of the F015 Luxury in Motion ensures optimum safety and supreme comfort for its passengers. At the same time, the bodyshell's structure provides the ideal basis for impact-protected installation of an F-CELL PLUG-IN HYBRID drive system, for the door concept that makes getting in and out especially easy, and for the communication-oriented seating featuring four lounge chairs in a face-to-face arrangement.
Mercedes-Benz currently designs standard production bodies based on the principles of "3D Body Engineering": comprising "aero engineering", "hybrid body engineering" and "safety engineering", it covers the three key dimensions of body manufacture. By employing new materials and structures, it was possible to build on this design principle and turn it into the highly efficient "Smart Body Structure (SBS)" for the F015. This intelligent hybrid lightweight construction, which uses the right material in the right place, combines innovative materials in a way that suits requirements, thereby maximising strength and crash safety while also optimising weight.
To dissipate impact energy, for example, conventional steels have been replaced by fibre-reinforced plastics (FRP), particularly those composed of carbon fibres (carbon-fibre-reinforced plastic, CFRP). The developers were able to harness the company's many years of experience in the world of Formula 1 here: the specific energy absorption rate of this motorsport material in an impact is four to five times higher than steel or aluminium, resulting in a far lower weight too. This takes occupant protection into a new dimension. By cleverly combining CFRP, aluminium and high-strength steels in a way that matches the varying requirements exactly, the lightweight engineering experts were able to make the bodyshell 40 percent lighter compared to today's production vehicles.
The Mercedes-Benz development team replaced the steel side members that have previously been the norm with plate-shaped multi-chamber sections made from an extremely light CFRP composite. Together with additional cross-bracing above and below the firewall, this produces a highly efficient and very rigid front box unit that both carries and encloses the fuel cell, preventing components from being damaged in the event of a collision. The impact energy is absorbed within a very short distance by the highly effective energy absorption structure before reaching the drive unit. A similar construction can be found at the rear of the vehicle housing the two electric motors, important control units as well as high-voltage components.
As a consequence, the F015 Luxury in Motion affords the best possible protection not just to its passengers, but to the high-tech drive components on board too. This is particularly true in the case of a side impact, thanks to the highly rigid occupant cell's energy storage concept featuring a mixed CFRP/aluminium construction. Within this ENERGY SPACE structure, the pressurised hydrogen tank system's slim cylinders can fulfil an important role. They are made entirely of high-strength CFRP and are positioned crosswise to the direction of travel. The cavities between the hydrogen cylinders are filled with special extremely robust structural components, thereby increasing the inherent stability of the ENERGY SPACE substantially. The storage tanks are furthermore secured by means of special CFRP mounts with a customised cross-section, that extend for 250 millimetres beyond the left and right of each pressure cylinder. This supplementary load path structure lets the ENERGY SPACE absorb even more impact energy without collapsing. Together with the crash-optimised sidewalls and the aluminium/FRP construction of the side sills, this produces a high-strength vehicle assembly overall. This sophisticated design has the two-fold benefit of bracing the body's structure in a side impact and effectively protecting both occupants and technology alike.
Meanwhile, there is room for the pressurised hydrogen tanks, the wiring and the inductive charging unit for the high-voltage battery in the extended floor assembly. This is also where the innovative new seating is secured that allows the passenger a vis-Ã -vis configuration.
Innovative opposing door system with no B-pillar
Another key element of the body design concept is the innovative saloon-door-style system featuring rear-hinged rear doors. The front and rear doors can be opened and closed independently of one another. All the doors open 90 degrees, allowing for very easy access to the spacious interior. Thanks to the specially structured body, it has been possible to dispense with a B-pillar. A very sturdy interconnected system with mechanical locking elements ensures exemplary safety standards. These elements securely interlock the front and rear doors when they are closed at the same time fixing them firmly to the roof frame and side skirts. The resulting composite load path allows an extremely high amount of energy to be absorbed in a frontal or side impact with minimal intrusion into the passenger compartment.
To make it possible to open the front and rear doors independently, the body design experts at Mercedes-Benz developed a special double hinge for the rear doors that is attached to the C-pillar. This allows the rear door to be released from the interconnected system separately with a fluid sliding movement backwards before pivoting out to open fully. To ensure supreme comfort, all door operating mechanisms are powered electrically and fitted with obstruction sensors. The sealing concept for the door system is the same as that used on the current Mercedes-Benz S-Class, an automatic power closing feature offers added ease of operation, plus there is that solid closing sound so typical of Mercedes.
The doors themselves have a crucial role to play in the vehicle's passive safety concept. This is not just down to their pioneering design, featuring a bionically enhanced aluminium inner structure and an outer skin made from carbon fibre. The crash-responsive beltlines in the doors underneath the side windows also have a vital effect. Already unveiled on the ESF 2009 Experimental Safety Vehicle and now fitted in a more advanced version, PRE-SAFE Structure is an innovation that offers maximum safety while taking up minimum space: in a collision from the side, these bodywork elements "inflate" in an instant, just like an airbag, allowing them to absorb as much impact energy as possible.
The passengers are also given optimum protection if the vehicle should roll over: a high-strength roof frame structure in a hybrid FRP/steel construction extends from the front right through to the C-pillar at the rear. The rear section of the roof is made from an aluminium mesh structure offering high structural rigidity and energy absorption on the one hand and low weight on the other.
A team of experts from a whole variety of technical disciplines together developed the groundbreaking bodyshell and ENERGY SPACE concept using state-of-the-art development and evaluation tools.
The powertrain engineering: 1100 kilometres of zero-emission driving
The F015 Luxury in Motion was designed to allow integration of an electric drive system with fuel cell. This is based on the pioneering F-CELL PLUG-IN HYBRID system seen in the F 125! research vehicle from 2011, and combines on-board generation of electricity with an exceptionally powerful and compact high-voltage battery. In order to store the hydrogen the concept offers pressurised tanks made from carbon-fibre-reinforced plastic (CFRP).
Whenever the driver wishes to summon maximum power or extend the overall range, the battery is used as an additional energy source. The battery can be recharged by using non-contact induction technology. This convenient, non-contact charging method can be monitored and controlled using a smartphone. The electric hybrid system has a total range of 1100 kilometres, including around 200 kilometres of battery-powered driving and around 900 kilometres on the electricity from the fuel cell. This enables the F015 Luxury in Motion to cover distances similar to those of a comparable diesel-engined car, but purely on electric power with zero local emissions.
Enhanced fuel cell system
The fuel cell stack on the F015 has been further optimised in terms of performance, efficiency and durability, and delivers the traction current for two electric motors, each with an output of 100 kW (136 hp). These are installed in a compact arrangement in the rear end of the vehicle and transmit their drive power to the rear wheels. The electrical drive system generates a total peak power output of 200 kW (272 hp). The maximum torque of 200 Nm per motor is available the instant the vehicle starts off, which results in impressive acceleration: the F015 completes the sprint from 0 to 100 km/h in 6.7 seconds and goes on to reach a governed top speed of 200 km/h. Its consumption equates to just 0.60 kilograms of hydrogen per 100 kilometers, the equivalent of 2.0 liters of diesel. (All consumption figures are combined figures measured in accordance with the NEDC New European Driving Cycle).
Fuel cells generate electricity from the reaction between hydrogen and oxygen. While working to further improve the fuel cell system, the overriding objective of the Mercedes-Benz engineers was to double the power output without changing the compact overall size. Their efforts focused on the possibility of increasing the speed of the chemical reaction within the system. This was achieved thanks to an array of individual measures, such as the innovative platinum catalytic converter coating using homogeneous nanoparticles of optimum size, and reduction of the electrical resistance in the stack's layers of cells. An improved electric turbocharger increases the airflow rate and thereby speeds up the chemical reaction.
More volume: structurally integrated pressurised hydrogen tanks
The F015 Luxury in Motion stores the hydrogen for generating electricity in 700 bar tanks that can be integrated into the floor of the car to keep them protected from impacts. The extremely slim pressure cylinders hold 5.4 kilograms of hydrogen in total and are made from carbon-fibre-reinforced plastic (CFRP). Thanks to their small diameter, the pressure cylinders can be fitted horizontally into the F015 floor without encroaching on the space for the passengers in the vehicle interior. Besides taking up very little space, the pressurised hydrogen tank system in the F015 Luxury in Motion offers other benefits too. It allows fast hydrogen refuelling in just a few minutes and is compatible with the H2 filling station standard used today.
Compact high-voltage battery with high energy and power density
The ultra-compact high-voltage battery can be installed in the front end of the vehicle together with the fuel cell system and has a capacity of 29 kWh. This amount of energy content gives the vehicle an electric range of approx. 200 kilometres when travelling purely on the battery's power, and can also briefly boost the drive system's power output when accelerating, for example. With 450 Wh and 1.2 kW per litre, it would make it equally suitable for use in series production in both PLUG-IN HYBRID and all-electric vehicles. By recuperating energy when coasting and braking, the high-voltage battery can be recharged during the journey, further improving the excellent energy efficiency of the system as a whole.
Technical data for F-CELL PLUG-IN HYBRID drive system F015 Luxury in Motion
Peak output of rear motors: each approx. 136 hp (100kW)