All-new 3rd generation Audi A8 luxury sedan

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New 3rd generation Audi A8 deploys it technologies
From its own onboard network to received satellite data

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Continued... In the new A8, the ESP system offers the choice of a sport mode in which, engine intervention is largely deactivated and brake intervention somewhat reduced for a more dynamic driving. It also offers other functions.

Two radar sensors are installed in the air inlets at the front.

For instance, the ESP system stabilizes a trailer that is threatening to fishtail by braking the wheels of the A8 in a rhythm opposed to the oscillations. This intervention takes place in three stages depending on how critical the situation is.

The stabilization system works very closely together with the dynamic steering, the damper control system and the sport differential. Audi has networked the chassis control systems of the new A8 in a manner so that they work faster and more closely together than before, with the ESP controller serving as the central integration platform.

The standard tire pressure indicator is also integrated into the ESP. This system measures indirectly, has no sensors of its own and thus adds no weight and requires no maintenance. It compares the speeds of the four wheels as measured by the ABS sensors, and also monitors changes in tire vibration caused by stimuli from the road. In the event of a loss of pressure, the amplitude and characteristics of the frequency of the tire change significantly, from which a change in pressure can be deduced.

Driver assistance systems

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The new high-tech assistance systems offered by the new A8 regulate the distance to the car ahead, help the driver to change lanes and stay in the lane, and assist with parking. They recognize speed limit signs and see far ahead into the night. Here is how each of them works.

Adaptive cruise
control + stop & go

The radar-aided automatic proximity control system, adaptive cruise control with stop & go, brings a major advancement over its predecessor. It regulates the speed and the distance to the vehicle ahead by accelerating and braking in a speed range from 0 to 250 km/h (155.34 mph), and brakes automatically within certain limits. Because the ACC stop & go function works together with the navigation system, it knows the course of the route in advance.

In stop & go traffic, the system brings the new A8 to a stop roughly four metres behind the vehicle ahead with no intervention from the driver. If the stop is brief, the sedan automatically resumes moving again; after a longer stop the driver must tap the accelerator or the cruise control lever. The driver can also anticipate and do this while the A8 is still stopped. The car is then ready to depart for the next 15 seconds and follows the vehicle ahead as soon as it begins rolling.

The two radar sensors of the system are installed in the air inlets at the front of the car (see photo below) and are automatically heated when it is cold. They transmit radar waves at a frequency of 76.5 gigahertz covering a 40 degree wedge-shaped field measuring 250 metres (820 ft) in length. A computer uses this to analyze the traffic situation in front of the vehicle and detect the preceding vehicles.

Sensors (pink) of the various driver assistance systems.

The interval to the vehicle ahead is adjustable in four steps. Deceleration is limited to 4 m/s² – a third of the maximum and subjectively equivalent to stepping on the brake pedal with medium force. The six-piston pump at the heart of the brake system generates the necessary pressure.

ACC + navigation data + video

Thanks to its broad networking, the adaptive cruise control with stop & go function works closely together with other driver information systems. Basically, it takes data from 27 control units, with which it works to continuously analyze the complete area around the vehicle and compares the results quickly, enabling the system to recognize complex scenarios and predictively support the driver.

For instance, if the vehicle driving ahead on a country road signals right and brakes because it wants to turn off, a conventional system only knows one way to react: it brakes like the vehicle ahead and will even come to a stop in certain circumstances. In the A8 with adaptive cruise control and stop & go, the system is aware of the intersection from the navigation system’s route data and uses the video images and the long-range radar to analyze the situation as it arises and normally behaves like the driver would: it brakes gently and lets the A8 approach closer to the turning vehicle. Once the driver decides to pass and signals to the left or turns the wheel, the ACC stop & go shifts its measuring area to the left and reapplies the gas – and the A8 quickly passes the other car.

The ACC stop & go also uses its network capabilities in many situations on the highway. Whether another vehicle pulls into the A8’s lane or the A8 is closing on a slow-moving vehicle in front of it, the system should handle the situation calmly, making driving more fluid and harmonious. If the driver wants to pass, a second optional assistance system comes into play: Audi side assist.

Audi side assist

Audi side assist activates at speeds above 30 km/h (18.64 mph).

Audi side assist activates at speeds above 30 km/h (18.64 mph). Two 24-gigahertz radar systems in the rear cover what is happening behind the A8 to a distance of 70 metres.

If another vehicle moves into the critical zone – if it is riding in the blind spot or approaching rapidly from the rear – a yellow LED indicator illuminates in the casing of the driver’s side mirror; the driver sees it only when looking directly into the mirror.

If drivers activate their turn signal to change lanes in spite of the warning, the indicator becomes brighter and flashes at a high frequency. The display is such that in practice it is only visible to the driver. Its brightness adapts to ambient light conditions and can also be adjusted via the MMI control terminal.

Audi lane assist

Lane assist and variable headlight range control: field of vision.

At speeds above 65 km/h (40.39 mph), Audi lane assist warns the driver when he or she is about to leave the lane inadvertently.

A camera mounted in front of the rear-view mirror observes the road to a distance of 60 metres (197 ft) and a coverage angle of 40 degrees. It delivers 25 high-definition images per second. Sophisticated software processes the images, identifies the lane markings and the course the A8 is following between them.

Audi lane assist with variable headlight range control.

If the driver allows the car to wander in the direction of a lane marking but has not indicated that he or she intends to make a turn, Audi lane assist warns the driver by vibrating the steering wheel. The vibration is generated by a vibration motor in one of the spokes; its intensity can be adjusted in three stages using the MMI. The timing of the warning is also selectable – before the wheel touches the line, when crossing the line or at the discretion of the system.

Compared to the previous version, Audi lane assist has become more powerful.

Audi lane assist vibration element in the steering wheel.

For instance, the colour camera can differentiate between the yellow line in construction zones and the white ones. It meets its limits under particularly unfavourable conditions, such as in the snow or if the road surface is very dirty. It informs the driver when this is the case.

The camera of Audi lane assist also serves a number of other functions. It provides important imagery for the ACC stop & go – it can detect vehicles on the road ahead and recognize when they signal. Its data also go into the startup function in stop & go traffic. The camera’s images also play an important role in emergency braking initiated by Audi pre sense front and for the continuous headlight range control.

Speed limit assistant

The camera in the base of the mirror is also used by the speed limit display that will be available from mid-2010. It detects the signs on the side of the road and their supplemental panels referring to wet conditions or times of day, for example. It shows the signs with the supplemental panels as graphics on the instrument cluster display, so that the driver can see the current speed limit at a glance.

Night vision assistant

Also debuting in the new Audi A8 is the night vision assistant. It uses a thermal imaging camera mounted behind the outer left of the four rings at the front of the car and has a wide, 24-degree angle of view. Its protective window is cleaned when dirty and heated when cold.

The thermal imaging camera of the night vision assistant.

As a far infrared system (FIR), the camera reacts to the heat radiated by objects. A computer transforms the information from the camera into black-and-white images and displays them on the central display located between the instruments. The view continuously tracks the road and the course of the A8.

Audi says that its choice of the far infrared technology is based on significant strengths, particularly when compared to other near infrared systems. Independent of driving speed, it can look as far as 300 metres (984 ft) ahead, far beyond the range of the high beams, and therefore is not blinded by headlights and similar light sources. It concentrates on the essentials: animals and people. Regardless of whether they appear bright or dark to the human eye, they are conspicuously bright in the image due the heat they give off, whereas the cooler road appears dark.

Persons are detected at a range of 100 metres.

The image processing software can detect persons at a range of 100 metres (328 ft). When analyzing the data, it specifically seeks out human contours and objects that are bright and round. Traffic lights, tail lights, and similar light sources are subtracted out. Detected persons are highlighted with yellow markings on the display. If the control unit assumes a hazard because a person is walking on the road close to the car, for example, the person is highlighted in red and a warning gong sounds.

Audi adds that it made a conscious decision to not use the first-generation night vision devices, which did not have this highlighting function. Studies have shown that they tend to increase the burden on the driver in critical situations. The system in the new A8 adjusts its range and warning thresholds to the speed driven.

The marking, the gong, and image contrast can be configured via the MMI. Like every assistance system, the night vision assistant also works within certain limitations. Pedestrian highlighting is switched off at temperatures above 28 degrees Celsius, for example.

Parking assist systems

The new A8 is available with two optional parking assist systems. The parking system plus uses four ultrasonic sensors up front and in the rear to indicate the distance acoustically and graphically on the MMI display. The front sensors also monitor the starting zone immediately in front of the car for the ACC stop & go when the A8 is creeping along in traffic.

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The parking system plus with reversing camera also uses a light-sensitive external camera. Mounted in the trunk lid, its fish-eye lens covers a broad 130 degree field of view. The images generated by this camera are processed to remove distortion and displayed on the MMI operating system monitor. Guidelines and fields show the car’s projected path.

3rd Gen. Audi A8	Body and exterior	Interior, network	Engines	Transmission
Steering, suspension...	Active safety	Passive safety	MMI & media	Dimensions

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