|February 5, 2006
Developing the Audi Q7: Virtual Worlds and a Car for the Senses
In the words of Prof. Dr. Martin Winterkorn, Chairman of the AUDI AG Board of Management: “The Audi Q7 represented uncharted territory for Audi – both in its own product range and on the competitive scene. The market had no similarly sporty and dynamic, but also spacious, multifunctional vehicle with off-road capability to offer. To achieve this position was the special challenge our development teams had to face.”
Almost 5,000 people work in Technical Development at AUDI AG. Since 2002, many of them will have been engaged to a greater or lesser degree on the project bearing the internal Audi number AU 716: the development of the Audi Q7. But in addition to the many technical departments, experts from Production, Toolmaking, Quality Assurance and Marketing were brought in from the first concept and design sketches onwards. There can be no doubt that creating a vehicle such as the Audi Q7 is one of the most complex tasks encountered anywhere in industry. So many of the tasks it involves can only be hinted at or described in brief here.
At Audi, the engineers, designers, mathematicians, physicists, industrial chemists, mechanics, shop-floor personnel, electronics and IT experts work in virtual computer worlds, on crash circuits, test rigs and other test equipment, in wind tunnels – or in worlds of the senses. But they have all contributed to a fine result: a third-generation sports utility vehicle (SUV).
One of the most important reasons for buying a car has always been its appearance – in other words, its design. The designers are the first people to concern themselves with a new vehicle project: they give the idea its actual shape. Even for the Audi Q7, the process starts in a ‘classic’ way, with pencil and sketch pad. Audi Q7 design project manager is Canadian Dany Garand, who recalls: “The Audi Q7 design process was a special challenge for our team. We had to create a product that was totally new for Audi, and bring the normally rather crude design of an SUV into harmony with Audi’s formal idiom. The kind of SUV on the market today would not have suited us.”
The varied demands that this vehicle segment has to satisfy in the European, American and Asian markets also had to be taken into account. Garand comments: “Consumer profiles in Europe and overseas are distinctly different, and during the design process we had to bear these regional patterns of life in mind. This included the Audi Q7’s overall size, its maximum capacity of seven seats, specific storage facilities and even new colour concepts both inside and out.”
Audi’s large SUV project acquired concrete form midway through 2002. Garand explains: “After the concept had been largely finalised, we succeeded in developing and building the fully functional Audi Pikes Peak quattro show car in only six months, so that it could be shown to an international public at the Detroit Motor Show. We wanted to establish how the public would react to our vision for this vehicle segment.”
The response was overwhelmingly positive – an ideal brief for the designers, who were then able to base their styling work on the “Pikes Peak” rather than having to start again from scratch. Garand: “We saved a considerable amount of time when it became clear that many of the show car’s basic features could be adopted on the production model.”
Some 150 members of Audi Design at the Group’s head offices in Ingolstadt, led by Gerhard Pfefferle, then began intensive creative work on the Audi Q7’s interior, exterior, colour schemes, equipment and trim. The aim, in Garand’s words, was to “unite the best of four worlds” in the new SUV: the dynamic, sporty lines and road behaviour of a sports coupe, the comfort of a luxury saloon, the technology and strength of an off-roader and the space and versatility of a van. The designers produced three different concepts, one of which was chosen for further work.
Body designer Satoshi Wada explains the exterior features of the chosen concept in the following terms: “The Audi Q7 is homogeneous in the ratio of overall height, length and width, with a short front overhang and a rather longer one at the rear. Like the A6, the body tapers considerably in plan view, and divides visually into volumes above and below the dynamic boundary line. The Audi Q7 therefore looks sporty and elegant above this line, but sporty and robust below it.” For its Japanese designer, the Audi Q7’s outward values are emphasised by its coupe-style roof line, the close-to-vertical angle of the Audi single-frame grille, the innovative rear-end styling with single-unit rear lights and the boldly flared wheel arches and large wheels.
Inside this SUV, the creative minds have adopted an “island design” principle. Interior designer Uli Beierlein and his Dutch colleague Mattijs van Tuijl describe this as “closed, single-colour surfaces, entirely made from one material, interrupted by islands containing the functional units.”
Beierlein: “The three easily identifiable islands are the door island (the inside door trim), the seat island (the seat locations) and the driving-area island (the cockpit and centre console unit). These islands are distinguished by their functions and differ both visually and in terms of touch from all the other surfaces.”
Van Tuijl adds: “The interior makes a lasting impression because of its clear architecture, perfect ergonomics and top-quality materials and craftsmanship.”
This is the point at which colour and trim designer Ute Grönheim took over. Together with her colleagues, she selected suitable fabrics, materials and paint finishes for the Audi Q7. She comments: “Colour and the nature of the materials tell us a lot about a car and its owner. The colour of a car is the first thing you notice about it, and is therefore an excellent way of stimulating the emotions.”
To create this initial emotive response, eleven standard paint finishes are available, some in metallic and others in pearl effect, from Calla White to Garnet Red and from Condor Grey to Phantom Black. Customers can also have the sill areas of the Audi Q7 finished in Silver or Grey as a contrasting colour. New colours with a specific SUV affinity are Sycamore Green and Bahia Beige, metallic. Ute Grönheim explains that each colour is applied to an actual vehicle before being approved: “They simply can’t be shown realistically enough as a virtual display.”
The forceful but at the same time luxurious feeling that prevails inside the Audi SUV is emphasised by various high-grade materials and fabrics. The designers created fine (“Verano”) and coarser-grained (“Cricket”) leather upholstery and trim, and developed a new type of carpet known as “Fresco” and the “Cosmo” seat upholstery fabric. Three kinds of wood inlays from three different continents are available: American burr walnut, European burr olive ash and Tamo, from a tree that grows in Japan.
Ute Grönheim illustrates the difficult task that the designer has to perform when identifying trends: “Our own tastes have to take second place when choosing materials and colours. On the contrary, we have to work out what will appeal as strongly as possible to customers in various markets in a few years’ time.” A car is a long-lasting product, but can be confronted with fashionable preferences and trends in taste that prove to be relatively short-lived.”
Development of the concept
Not everything that seems ideal from a design standpoint can be implemented as a practical technical concept. When the designers start their work, therefore, their colleagues in Concept Development begin to realise the vehicle project at the same time. As Ralf-Gerhard Willner, Head of Vehicle Concepts at Audi, puts it: “We are to some extent the mediators between the various worlds.” He defines his task as tracking down the best possible compromise between emotive styling, customer-relevant and legally permissible demands and the concept’s technical feasibility.
One of the main tasks of Concept Development is to lay down the vehicle’s principal dimensions and its architecture. The engineer Felix Biffar undertook this work for the Audi Q7 project: “From the very outset, the emphasis when the package was drafted out for the Audi Q7 was on typical Audi qualities: design, driving dynamics, safety, the operating concept, comfort and convenience.” One of the first assumptions for the AU 716 project, he goes on to explain, was for a third row of seats to be an option. “Market surveys have confirmed that customers want this kind of flexible, purpose-orientated seat arrangement in a vehicle of this size,” explained Biffar.
A wheelbase of three metres was therefore chosen. The high seat position characteristic of an SUV was also included in the requirement specification from the very start, as were sporty handling, an above-average level of comfort on long journeys, off-road capability, ample room for the occupants and the largest load area in its class.
Another requirement was that despite its imposing dimensions, with an overall length of more than five metres and a width of almost two metres, the Audi Q7 should have a sporty visual character. Also finalised by Concept Development at a very early stage: the size of the wheels, the range of engines and transmissions to be offered, the use of air suspension, the MMI operating concept and the capacity of the fuel tank. Biffar comments: “We wanted to create a “performance SUV” from the outset, with a combination of emotive design, comfort, agile handling, luxury, flexibility and space – something that no model in the SUV segment had so far succeeded in achieving.”
By the end of 2003, the technical aspects of the Audi Q7’s specification had been largely finalised. As far as the main dimensions were concerned, the concept development team was able to make rapid progress by using the show car as a basis. Biffar and Willner describe the procedure as “lean”, and even as “relaxed” in comparison to other projects. Willner explains why: “Our advantage was that the Audi Q7 was an entirely new product for us. There were no preconceived opinions, and we didn’t have to base our work on a previous model.”
When development work began, the core team consisted of just 20 people, but the total number went up steadily as the project continued, until in the end about 500 men and women were working exclusively on Audi Q7 development.
Virtual worlds: simulation and computing
Among these employees were many who were closely involved in the car’s progress, its appearance and its design long before they were able to handle a single component “in the flesh”. Never before had such intensive use been made of computer-aided simulation tools from the virtual world. Never before had so many of the Audi Q7’s characteristics been portrayed with the aid of bits and bytes, and never before had so few actual prototypes been built and, at the same time, such a high level of production maturity attained.
The advantages are obvious: everything than can be designed, destroyed, tested, modified and displayed on a screen in the virtual world of the computer only needs to be confirmed when actual hardware – culminating in the “real car” – becomes available. This not only cuts development time and cost but also boosts quality, since any conflicts of objective affecting the car can be eliminated even more accurately and efficiently.
This is the world in which terms such as Computer Aided Design (CAD), Computer Aided Engineering (CAE), Digital Mock-Up (DMU), Finite Element Method (FEM) or Virtual Reality (VR) are bandied about all the time in conversation among the technical specialists. They work with super-computers, microprocessors, power walls, gigantic volumes of data and the very latest software technologies. This is where the classic skills of mechanical engineering and vehicle design come together with advanced mathematics, lattice structures suitable for input to the computer and complex differential equations. There is very little that the computer cannot calculate and simulate.
The list of areas in which simulation technology is used in motor-vehicle manufacturing is a long one: body rigidity, strength and operating life, avoidance of unpleasant vibration, doors, lids, occupant protection, interior components, joining techniques and crash performance can all be displayed by these methods, as can driving dynamics, ride comfort, fuel consumption, sensor operation, aerodynamics and aero-acoustics, heating, ventilation and air conditioning, headlights, suspension characteristics or the actual combustion process in the engine. Many others could be mentioned too: Audi Technical Development currently uses some 250 simulation methods in production areas.
Even in the early vehicle development phase, colleagues from the Toolmaking, Production or Test Construction departments participate actively: as elements in the “digital factory”, they can simulate how certain sheet-metal parts can best be made (or if they are suitable for production in their initial form). In an imaginary production shop, the spot welds to be produced by the robots are decided upon, and the robots’ own positions determined so that they keep clear of each other while performing the necessary movements.
In the “Cave”, as it is called, an engineer from Test Construction wearing 3D goggles extends a fully movable “virtual hand” into the Audi Q7’s body. He is using this authentic three-dimensional environment to check whether an employee on the assembly line will later be able to install, for example, a seat designed on the computer or the vehicle’s roof lining easily without any collisions with other components occurring. Nor should we forget that all this happens at a time when neither the car itself nor any of its components have been built.
At the power wall, a back-projection screen about 6 metres wide and 2.5 metres high, everyone involved in the development process, from technicians to members of the Board of Management, can view a virtual picture of the Audi Q7. Almost every detail can be displayed, even the surface texture of materials used inside the car.
With a single mouse-click, the car can be turned for viewing from every possible perspective, or the observer can make a circular flight all around it or through the interior. Various paint finishes and equipment specifications, as well as left- or right-hand-drive versions, can all be conjured up within a matter of seconds. The development engineers can even blend the real and virtual worlds together on the power wall, for example by displaying the virtual Audi Q7 in a real setting to see what effect is created when it is seen on the road.
Dr. Ulrich Widmann is Head of Functional Design at Audi. He knows the reasons why simulation technologies have now become indispensable: “A model such as the Audi Q7 is a highly complex combination of many different components and assemblies, with any number of different characteristics. To develop it and determine its performance by means of genuine tests would be totally impracticable. Such a mammoth task can only be tackled successfully by means of a vast number of virtual-world simulations.”
Even in the Audi Q7 concept phase, computing and optimising the design ratings of the vehicle package is a particularly important task. There are tools that permit the modular vehicle concept to be described by just a few different parameters – about 1,000 in all, each of which can be changed interactively. Adjacent design areas that are influenced by these changes are then modified automatically. For example, the complete B-post can be moved rearwards by five centimetres within a matter of minutes.
The volume of data necessitated by such a change is immense: for a crash analysis on a modern car, up to a million elements are now involved when calculating the results within a period of 150 milliseconds. To calculate the effects of a frontal collision, the super-computer with its eight processors needs about 22 hours.
When Audi Q7 development is complete, some 2,000 virtual frontal crash tests will have been carried out, compared with just over 40 on actual vehicles. Dr. Widmann: “Our forecast accuracy from these simulations is already 90 % or higher!” An important aspect of such processes is for all the departments taking part to be networked together at an early stage, so that all of them have access to the latest design data.
Widmann: “For the Audi Q7, we used an “Engineering Portal” for the first time that our suppliers were able to access directly as well.”
The experts’ term for this kind of closely interlocked development work that takes place in parallel is “Simultaneous Engineering” (SE).
“We never worked as intensively as this before in the virtual world. Together with an actual concept car to act as a basis for package decisions and convey a sense of space, we were able to reach the series-production development phase more rapidly”, says Dr. Widmann.
On the Audi Q7, virtual reality also played a decisive part in an area that can be regarded as a link between the design and construction departments: the “Strake”. This term, which came originally from shipbuilding, now refers to the geometrical representation of all the vehicle’s interior and exterior surfaces that are visible to the customer – taking all technical and formal aesthetic requirements into account. The “Strake” therefore embodies the core competence for the finest surface finishes and the associated quality.
“We act as a bridge between design, that is to say the aesthetic statement made by the design model, and construction, representing the technical activities of the Vehicle Development departments”, says Horst Schneider, who is in charge of “Strake” visualisation. According to his records, between 600 and 800 components with relevant surfaces are “straked” for every project.
As the product range continues to grow and become more varied, but the time available for development work becomes shorter, systematic use of virtual techniques is essential as an error filter and an aid to decision-making in the process. Horst Schneider explains: “If we wish to make decisions possible at early stages in the development process, we shall have to integrate virtual reality even more strongly into our day-to-day “straking” activity in the future.”
Whereas previously only one digital data control model was processed in virtual form, today construction and visualisation data are networked during the very first discussions (design, “straking”, project, simultaneous engineering, technical team) and can thus be prepared photo-realistically and used for decision-making.
Schneider: “There are various degrees of preparation for visualising the “straking” process. For a discussion on the overall impression made by the vehicle’s interior or the body, the quality is naturally many times higher that during a normal working meeting where a rapid general view of an individual part is all that’s needed.”
The general impression, lighting simulation, surface diagnosis, colour variants, view through to the rear or the production of pictorial material for Marketing colleagues are just some of the activities undertaken with VR in the straking process.
The Design Check is a kind of “barometer of maturity” during Audi Q7 development as a whole. It is a visualisation and decision-making process aimed at avoiding incorrect development steps and enabling clearly defined work instructions to be issued. The Design Check begins in the concept phase and continues until production starts. During this lengthy process, concepts and the current development-work position are visualised and verified at an early stage. The engineers operate both in visual worlds and with models, but also with “genuine” fully-functional vehicles.
The purpose of the Design Check is to render the complete Audi Q7 project transparent for everyone who is concerned with the vehicle’s development. Ergonomics and package dimensions, for example the door sills, legroom and headroom, loading through the tailgate, the view to the rear, the driving position and even the practicability of the cup holders can all be examined at an early stage during the Design Check. This is also where all the necessary product optimisation measures are agreed with the specialist departments, with the aim of enhancing series-production development quality and, as a result, the quality of the finished product.
A great many specialist areas were – and are – directly involved in development of the Audi Q7 to series production readiness. The project acquired much of its dynamic character from the engineers concerned with aerodynamics and aero-acoustics. Audi Q7 prototypes and pre-production vehicles spent more than a thousand hours in the Audi wind tunnel centre in Ingolstadt, which is one of the most modern anywhere in the world. The results are a drag coefficient of 0.34, the best value in the large SUV segment, and extremely low wind noise levels.
For Dr. Michael Jaroch, who with his team was responsible for Audi Q7 aerodynamic, aero-acoustic and water management development work, achieving such good results was far from easy. As he says: “Optimum design of a vehicle of this size, without any adverse effects on its styling, is a difficult balancing act for us.”
The Audi development engineers studied the airflow acting on the Audi Q7 in a vehicle wind tunnel that is both quieter and faster than those currently in use anywhere in the world. A turbine approximately four metres in diameter, with a drive rating of 2.6 Megawatts, delivers air to the wind tunnel at up to 300 kph.
The thermal wind tunnel is used to optimise the flow of air to the Audi Q7’s cooling systems. On this hi-tech test rig, the temperature can be varied anywhere between 20 and 50 degrees Celsius, and the airflow accelerated up to 275 kph. Even the floor of the measurement zone can be heated, to simulate hot road surfaces. Set into the floor is an additional roller for Audi models with quattro four-wheel drive.
A further development priority is water management. The aim here is to minimise interference with the driver’s view of the road as a result of dirt and water on the windows.
Dr. Jaroch illustrates this as follows: “Critical situations can for example arise if the car is following a truck along a wet road, and water spray from its wheels obscures the driver’s view. This can typically occur at speeds of between 70 and 90 kilometres per hour. Our aim in the case of the Audi Q7 was to optimise the airflow round the A-posts and exterior mirrors so that the side windows and mirror glass remain clean.”
How is this achieved? The vehicle is sprayed with a fluorescent liquid in a special wind tunnel devoted to surface contamination. Under black light, the paths taken by rain and spray and the areas where the water collects can be clearly seen.
Audi naturally keeps pace with the rapidly increasing importance of automotive electronics – in the Audi Q7 as in all other Audi models. For this purpose, an ultra-modern Electronics Centre has been specially built on the Technical Development site in Ingolstadt.
All Audi’s competence in electronics is concentrated in this seven-storey building, which includes space for future extensions. Some 750 employees from the Development, Purchasing, Quality Assurance, Production Planning, After Sales and Controlling departments work there.
Peter Dlab, in charge of Electrics/Electronics Project Steering for the Audi Q7, sees the significance of electronics in this way:
“Automotive electronics are a key technology, and have therefore been made into a core competence area at Audi.” In the cars of tomorrow, up to 90 % of all innovations will be based on electronics.
The volume of electronics is increasing all the time: navigation systems, on-board computers, infotainment, electronic engine and transmission management, airbags, ABS, ESP, electric windows and central locking – without electronics, none of these would function as they do in the modern car. A large number of electronic control units in the vehicle communicate with each other; Audi models have long since taken to the “data highway”.
An example will serve to show the unstoppable progress of in-car software integration: an Audi Q7 with top-level specification contains as many as 50 electronic control units and has a memory capacity of up to 90 Megabytes. Peter Dlab: “That’s precisely where the major challenge lies. We have to make these increasingly complex in-car electronic networks easy for the customer to operate, and also ensure that they process data reliably.” Another important aspect involves bringing the remarkable development progress that is being made in electronics into harmony with the comparatively lengthy life-cycle of the average car.
The Electronics Centre plays a decisive part in this strategy, by grouping all Audi’s competence in the electronics area under one roof. The terraced building complex provides workplaces for 400 electronics development experts, 80 employees from a variety of Purchasing departments and 50 specialists from Quality Assurance and Production Preparation.
Each of the project teams includes members from various company work areas, with efficient “cross-desk” communication between them.
Innovative electronics development naturally includes organisational changes, a minimum number of hierarchy levels, efficient processes and a young, highly motivated team. Project teams can be brought together at one point for various activities in a number of different areas, without major modifications to the room layout.
This is particularly important in the electronics field, since experts in widely varying disciplines often have to work together for limited periods on specific projects.
The Electronics Centre is not only impressive in its architecture: it is also equipped with the very latest measuring and testing apparatus, for instance a climatic roller test rig that is used to test operation and reliability of electronic components for the Audi Q7 at the most extreme temperatures and over a variety of road surfaces. This combined test rig can simulate arctic temperatures just as effectively as humid, tropical weather or the extreme heat of the desert.
The complete electronics for the Audi Q7 are tested on a board assembly, and the reliability and fault-free interaction of the components – up to 4,000 in all – checked in detail.
The MMI laboratory is entirely devoted to checking and developing all the functions to be performed by Audi’s innovative Multi Media Interface (MMI) concept in authentic operating conditions. MMI is standard equipment in the Audi Q7. There is also an ultra-modern acoustic laboratory in which the engineers perfect the sound system for the new SUV. Yet another impressive facility is the lighting test area, 50 metres long and 10 metres wide, which is used to develop new vehicle lighting systems.
Audi is already one of the leading car manufacturers in the electronics area, in which it has achieved a high standard of reliability.
The Audi Q7 also sets new standards in “chips, bits and bytes”. Not one but several innovative driver assistance systems have reached series production for the first time on this model. For example the “Audi side assist” radar-supported lane-change assistant and “parking system advanced” with its visual and audible signals and rear-view camera.
The ESP includes several new functions, such as the hill descent assistant. A special off-road mode optimises brake-system performance and traction on loose surfaces. A trailer stabilisation system uses controlled brake applications to reduce the risk of snaking when a trailer is being towed. None of these features would be practicable without electronics. The Electronics Centre will enable Audi to consolidate and extend the leading position it already occupies in this area.
As electronics are used to an ever-greater extent in modern cars, electromagnetic compatibility (EMC) is becoming an increasingly important topic. This term refers to a vehicle’s ability to operate correctly in an environment in which electromagnetic interference signals may occur, and also to avoid transmitting such signals if they could prevent other equipment from operating safely. Audi operates an extremely modern EMC centre in which the Audi Q7 too was exposed to a torrent of external radio signals.
The central element in this EMC testing centre is the big absorber room. It has metal screening and is lined with pyramid-shaped absorbers to reduce reflection of radio waves. In this futuristic setting, large aerials bombard the Audi Q7 with electromagnetic fields in the frequency range from one Megahertz to three Gigahertz.