Test-driving
To make sure that the Audi Q7’s features remain fully operational, even in extreme conditions, when the vehicle is in the hands of the customer, a test driving programme is carried out. Never before has a model been exposed to tests representing such an extensive range of potential tasks and applications as those to which the Audi Q7 was subjected. Before the first production vehicles are delivered to customers next spring, Audi Q7 prototypes and pre-production vehicles will have covered several million test kilometres.
Testing takes place at a variety of locations: on various test rigs, at the Volkswagen Group’s proving ground, on the Arctic Circle at minus 35 degrees Celsius, in the scorching heat of South African desert, sand and loose stones, on highways in Florida, on dusty tracks surfaced with gravel chippings in Europe, Asia, Brazil and Central America, and on the North Loop of the Nürburgring motor racing circuit. Every other kind of road is featured in the programme too: isolated, twisting country roads, German motorways and dense city-centre traffic.
Although still disguised, the Audi Q7 is on the road constantly, often in the farthest corners of the earth and in the most severe dynamic, climatic and topographical conditions (see MediaInfo “A tough test for cars – from South Africa to the North Loop”; 2 August, 2005).
Suspension and driving dynamics
The Audi Q7 is designed to master a variety of different driving tasks equally well: long-distance road travel, leisure activities and off-road driving. This calls for a combination of widely differing chassis and suspension characteristics. Audi’s development engineers have tuned the Audi Q7’s suspension systematically to achieve a standard of road dynamics previously considered impossible. Front-to-rear axle load distribution of 52:48 when unladen (V8 FSI) and quattro permanent four-wheel drive with dynamic load-dependent torque distribution are the keys to optimal road behaviour right up to the handling limits.
In the words of Thomas Kriegel, Head of Driving Characteristics Simulation at Audi: “We used DOE (Design of Experiments) methods to determine details of the suspension components at a very early stage in our development work. We chose the settings for the springs, shock absorbers, anti-roll bars and tyres to ensure harmonious, easily controlled handling in all operating situations.”
For example, to achieve the ideal combination of firmness values in various directions for the rubber-to-metal bushings, the Suspension Computing staff investigated several thousand versions in various load situations and for each axle. To make it easier to filter out the most suitable combinations of values, they established target ranges for all the main suspension performance areas. These were subsequently investigated in more detail. It was found for example that the firmness of the steering box mountings, together with the front wishbone pivot bushings, determines the lower levels of acceptable agility and dynamic stability.
By means of thorough road testing, the engineers arrived at a typical Audi combination of sportiness and ride comfort, whether the vehicle was fitted with steel springs and conventional shock absorbers or air suspension with controlled damping. Thomas Kriegel sums up: “Air suspension offered us additional scope for optimising high-speed dynamics. Firmer shock-absorber settings and step-by-step lowering of the body for aerodynamic reasons have the effect of stabilising the Audi Q7’s handling still further. Compared with competitors, it has the best dynamic driving characteristics.”
To achieve this, the development team had to take a number of different aspects into consideration: a premium-class SUV, for instance, is a popular choice for long journeys on account of its high seat position and its attractive interior trim. The occupants naturally expect ride comfort to reach an equally high standard.
Thomas Kriegel explains how this was achieved: “An initial aid to determining the ride-comfort settings was an operating-point analysis, using details of the forces measured in the rubber bushings.” For this purpose, the computing engineers simulated excitation from the road surface (for example rough asphalt, cobblestones and lateral joint lines) using a high-resolution multi-body model of the Audi Q7. In this way, the bushings could be ideally matched to the forces that occur when the vehicle performs movements relevant to occupant comfort.
Kriegel concludes: “Finally, these and other changes to suspension components were assessed repeatedly for acceleration values at the “comfort points” such as the steering wheel and seat, using a complete-vehicle model, so that we obtained an excellent starting situation for fine tuning on the road.”
A car for the senses
When a new Audi model is being developed, what are known as the “soft factors” are also becoming increasingly important. Apart from the visual satisfaction of a well-styled vehicle, the senses of hearing, smell and feel also played a signficant role in Audi Q7 development. Audi was one of the first car manufacturers to recognise the importance of these factors and set up special teams to work on them.
One of these teams deals with haptics. Gerhard Mauter, Head of the Control Haptics team, is an engineer “with feeling”, so to speak, though this scarcely hints at the full extent of his work. Haptics are the science of touch, but here again the task is not limited to making an Audi feel pleasant wherever the occupant comes into contact with one of its surfaces. Ergonomics, control logic, smooth movement and attractive appearance also play their part whenever controls and switches are pulled, pushed, pressed, slid, turned or simply touched inside the car.
How does one find oneself working in such an esoteric area? Gerhard Mauter explains: “It’s important for haptics to be taken seriously, and also for one to approach the subject with a certain degree of sensitivity. This of course starts quite literally at the fingertips, but it goes beyond such physical characteristics and largely takes place in the mind.” Mauter has been in charge of the haptics team for more than five years now; it was first formed back in 1995 – a sign that Audi has always taken this topic very seriously indeed.
There are good reasons for this: haptics are of considerable importance in the car. The impressions gained by touching and handling the controls and surfaces exert a strong influence on the potential customer’s purchase decision. Whoever sits in an Audi should feel good from the start. To make sure that this applies to all Audi models, the haptics team was set up.
Then there is the Audi “Nose Team”: its job is to “poke its nose” into every possible part of the car, to track down objectionable smells and to ensure that the inside of an Audi, is always consistently agreeable. Plasticisers exuded by synthetic materials, leather with an odour of fish oil, floor mats that smell as if they had been in contact with onions – none of these have a chance to spoil the quality of an Audi car. Nor, of course, have materials that could produce emissions that represent a health risk.
As many as 500 parts used inside each model are analysed by the “artificial nose”. Audi sets benchmark standards for the industry in odour avoidance. The aim is not so much the avoidance of all odours as the production of an “odour-neutral” car in which the customer always encounters a pleasant atmosphere. Heinz Stahl, who heads Audi’s team of odour detectives, says: “Eliminating all smells would be more or less impossible, and not particularly desirable either. It would be comparable to travelling in an acoustically dead vehicle.” Every car is now a sensory pleasure.
How should this be understood? Stahl explains: “We spend quite a lot of time in our cars, so that our sensory perceptions are becoming more and more important.” A new car should always have a typical odour, but of course not an objectionable one. This is the task tackled by the “olfactory experts” (olfactology is the scientific study of odours). What may seem only of secondary importance compared with other aspects of the car can subconsciously play a fundamental role for the customer.
The leader of the “Nose team” explains this by reference to the comfort hierarchy, which has been confirmed by scientific investigations: “Imagine this in the form of a pyramid. The customer’s well-being is right at the top, the car’s odour is down at the bottom. If an unpleasant smell comes to the customer’s attention, he or she no longer senses all the car’s other comfort and convenience aspects in a positive way, but is totally irritated by the objectionable smell.”
In the sound design area, the important thing is to strike the right note – something that Audi achieves with particular success in its cars. Acoustic development work has become an important element in car development at the Ingolstadt-based manufacturer, and one of the calling cards of the brand with the four-ring badge. How should an Audi sound? That depends on the type of vehicle, and also on what the customer expects. For the Audi Q7, the sonic image can be described as “powerful and sporty”.
Dr. Ralf Kunkel, Head of Audi Acoustics, is the conductor of the “Audi orchestra”. As an engineer, his choice of words is perhaps unusual: as well as using this term, he speaks of “composing” and “directing”, of “good musicians”, of “out-of-tune players” and of the “Symphony of the Four Rings”. His guiding principle: “The sound must be what the listener expects to hear. Sound stimulates emotion.” He has a very convincing example to illustrate this: a photo of a glass of lager appears on the screen, but the sound track is of tap water being poured into the glass. The listener automatically registers the fact the picture and the sound don’t fit together. In other words, “we expect something and are then disappointed.”
One can apply the same logic to a car. Dr. Kunkel explains that the sound it makes must tie up with the expectations that the model positioning arouses in the customer. To put this another way: anyone who buys a Audi Q7, sits behind the wheel and presses the accelerator expects to hear a strong, sporty sound. Too much acoustic restraint would disappoint the customer in this case.
Yet at the same time, the sound must not be too obtrusive or begin to cause irritation as the journey continues. The Audi Q7’s acoustic image has therefore been slanted towards comfort in a way that also emphasises the vehicle’s supreme character in a fairly restrained manner. Dr. Kunkel: “For a model like the Audi Q7, everything has to blend together perfectly: design, performance, objective size – and sound!”
The “Squeak and Rattle” team is on the track of quite different sounds. Eckhard Peithmann, the leader of this group of “good listeners”, and his colleagues have located and suppressed just about every form of minor noise – from rattling to far more subtle sources of aural irritation – in the latest model families. During Audi Q7 development too, they conducted innumerable tests both on the road and on the company’s test rigs with the aim of driving any squeaks and rattles out into the open and eliminating the causes.
Some people at Audi call him simply “The Ear”. Peithmann himself smiles when he hears this nickname: “This is certainly a job that calls for good hearing – but also for plenty of patience! There are some sounds you simply can’t hear until you’ve run the test over and over again.” Those who not only hear them but somehow sense them too – these are Eckhard Peithmann’s most sought-after colleagues.
The listening team is made up of development engineers, and staff from Quality Assurance, Production and Customer Care. Peithmann’s verdict: “You don’t learn our job at school or in training sessions. And not everyone has the patience it needs.” Peithmann, a blues fan, has a strong dislike of rattling, unmusical glove box lids, squeaking seat frames or creaking plastic trim. But as he readily admits, suppressing obvious noise is not the real problem: his remedies have to work on a variety of road surfaces, at specific temperatures, speeds or after the car has covered a certain distance. Otherwise they may reappear to plague an otherwise contented customer.
Locating the origins of all these noise sources is an extremely complex, time-consuming task. Audi Q7 noise analysis took at least a year to complete. Every four to six weeks, the noise detectives take a test run, sometimes in icy-cold Scandinavia, sometimes on desert trails in North Africa.
Between these excursions, noise elimination continues intensively on the roller and vibration test rigs, climatic chambers, dummy-head microphones and hydropulsers in the Ingolstadt plant’s Technical Development and Quality Assurance departments. Peithmann: “Over the years, the number of trial runs and noise analyses has steadily increased, the reason being that the Audi model range has grown all the time and so new product launches naturally occur at more frequent intervals.”
But why do Audi’s acoustics experts have to go as far as the Arctic Circle in their hunt for noise sources? This is explained by Franz Lang from the Design Check and Test Run department, who is also a member of the “Squeak and Rattle Management Circle”: “We can find winter temperatures there down to minus 40 degrees Celsius. In a climate such as that, plastics lose their flexibility, their friction coefficients change and they are more likely to generate noise.” Exposure to extreme heat can have different but equally serious consequences, so that here too certain types of plastics in the car begin to creak or chatter.
At first glance, there’s something exotic about the way the noise eliminating team goes about its work. An acoustics engineer is quite likely to be found huddled up in the boot of the car during the test run, “just to hear what’s going on” – no manner how bumpy the road or how low the outside temperature.
The tester occupying the passenger seat may have his head down in the footwell and his feet on the head restraint during the test run, and be listening hard for a noise that’s difficult to locate.
Eckhard Peithmann sums up: “It’s true, we crawl into every nook and cranny on the car!” But since road safety risks have to be allowed for, these test runs take place on cordoned-off test tracks rather than on the public highway.
Quality assurance
All these efforts culminate in the high quality that has been achieved on the Audi Q7. Quality assurance personnel take part in development meetings from a very early stage. Marcus Hoffmann, who is responsible for Audi Q7 Quality Planning and Steering, says: “At the start, we were less concerned with detailed quality matters than with the task of determining what demands the customer makes of a vehicle such as the Audi Q7.”
In the next phase, the experts monitor the quality by means of design and data control models or prototypes. Hoffmann: “Quality has to be part of development work from the very start. It can’t be applied to the vehicle at a later stage.”
The quality assurance teams have borne the needs of American customers in mind throughout their work. As a model in the SUV segment, the Audi Q7 is closely geared to North American market requirements.
During development, the new model was therefore driven regularly from an early stage by staff from Audi of America and assessed in accordance with US customers’ preferences. Hoffmann: “In most cases, those who drove the car have day-to-day contact with customers and are extremely familiar with their wishes.”
In addition, experts from the American market research company J.D. Power and Associates were invited to Ingolstadt and their suggestions incorporated into the Audi Q7 development process. In the USA, J.D. Power is one of the most respected arbiters of consumer satisfaction: it issues a regular bulletin on this topic and assesses the quality of cars from the customers’ standpoint.
Hoffmann: “In this way we able to gain a picture at an early stage of how the US customer would react to the Audi Q7 and what he would expect of it.” Some of the results of this exchange of views are the large cup holders in the centre console, the bottle holders in all four doors, the way the air conditioning operates, which is somewhat different from European practice, and the folding mechanism for the third row of seats, which is child’s play to operate. But Hoffmann is nonetheless confident: “We have by no means neglected the wishes of other customers from around the world. We have simply combined these often very different requirements in the most effective possible way.”
Fine-tuning of technical, visible and haptic quality takes place at the pre-production stage. At Audi, one of the measuring instruments used for this is referred to as the “master gauge”. Versions for both inside and outside the car are used.
Even for Josef Junker, the Measuring Technology and Master Gauge Manager in the Quality Assurance department, the name is something of a mystery. But as he explains, “The master gauge is far more than just a measuring instrument; at Audi it’s an integral element in quality assurance policy.”
The master gauge is a ladder-type frame made of aluminium, on which the vehicle, including all the currently available parts, is built up, measured and assessed. These assessments take place once a week. A large group including suppliers’ representatives gathers round the master gauge and presents its components in the latest optimised versions to members of the Quality Assurance, Development and Production departments. Are the joint gaps ok? Is the “feel” of the surface acceptable? What impression does the part make when seen in or on the complete vehicle? Can the pushbuttons and switches be easily reached and operated without difficulty? Will it be possible to install the part later without problems arising on the assembly line? Many questions of this kind are discussed and the solutions arrived at during the master gauge meetings.
In this way, some three hundred parts relevant to the Audi Q7 are subjected to close examination. At two- to four-week intervals, the Board of Management visits the master gauge department to obtain a picture of the quality level that has so far been achieved. Junker: “The procedure is repeated until we know that we can maintain the high build quality that Audi is famous for.”
Coordination by model line management
But who controls the entire process? Audi has organised it according to model lines. Gerhard Hametner, the Audi Q7 and A8 Model Line Manager, explains: “The demand for an ever-greater variety of models increases pressure on the production process. This is a situation that applies to all car manufacturers. One of the most crucial challenges for AUDI AG is to keep control of this constantly expanding multi-project scene. Despite increasing complexity, new models such as the Audi Q7 must be developed successfully, launched punctually and be in accordance with customers’ wishes.”
Model line management is responsible for every aspect of the vehicle project: it controls project-related activities, monitors progress and, if there are signs of significant deviations from the targets, steps in and takes remedial action. Hametner sums up: “Model line management controls the Audi Q7 product process at cross-department level, almost as if it were a business within a business, from the decision to go ahead with the project to the market launch of the vehicle and its entire subsequent life-cycle.”
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