Assistance systems

The new A8 L comes with a wide and newly configured range of high-tech assistance systems that make driving even easier, more relaxing and more composed. These systems 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. The groundbreaking networking of these systems makes them unusually intelligent and capable.

Highly complex: adaptive cruise control with stop & go function
Probably the most complex assistance system in the A8 L is the Audi adaptive cruise control with stop & go function, a radar-assisted interval-maintenance system. It has been significantly upgraded versus the previous model. It regulates the speed and the distance to the vehicle ahead by accelerating and braking in a range from 0 to 250 km/h (155.34 mph), and brakes automatically within certain limits.

The system is particularly convenient in stop and go traffic, where it brings the large sedan to a stop with no intervention on the part of 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 do this while the A8 is still stopped. For the next 15 seconds, the car is then ready to pull and follows the vehicle ahead as soon as it begins rolling.

The ACC stop & go uses two radar sensors installed in the air inlets at the front of the car and which 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 meters (820.21 ft) in length. A computer uses these waves to detect the leading vehicles. The driver can set the time interval to the vehicle ahead in four steps and also specify one of three levels for the control dynamics. Deceleration is limited to four m/s².

The adaptive cruise control with stop & go function uses the predictive route data from the MMI navigation plus system, and works closely with the other assistance systems on board the A8 L. Receiving data from 27 control units, it continuously analyzes the complete area around the vehicle and compares the results extremely quickly. This high level of information enables the system to recognize complex scenarios and predictively support the driver.

The ACC stop & go uses its networked knowledge in numerous situations. Whether quickly passing a car turning right from an interurban road or if another vehicle pulls into the lane occupied by the A8 L on the highway, the system handles the situation with reflection and composure, making driving more fluid and harmonious.

Rearward looking radar: Audi side assist
Audi side assist activates at a speed of 30 km/h (18.64 mph). Two 24 gigahertz radar sensors in the rear monitor what is happening behind the and beside the sedan to a distance of 70 meters. Their data are analyzed by a computer. If another vehicle moves into the critical zone – if it is riding in the blind spot or approaching rapidly from the rear – the so-called information stage is activated. 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 the driver activates the turn signal to change lanes in spite of the warning, the indicator become brighter and flashes at a high frequency. This signal – the warning stage – can hardly be overlooked. The visual signal is designed so that in practice it is only visible to the driver. Its brightness adapts to ambient light conditions and can also be controlled via the MMI control terminal.

Keeping on course: Audi lane assist
At speeds above roughly 65 km/h (40.39 mph), Audi lane assist issues a warning if the driver 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 meters (197 ft) and a coverage angle of 40 degrees. It delivers 25 high-definition images per second. Software processes the images and identifies the lane markings and the course the A8 L is following between them.

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. Vibration intensity and the point at which the warning starts can be selected in three stages. Audi lane assist has become much more powerful compared to the earlier version. For instance, the color camera can differentiate between the yellow line in construction zones and the white ones.

The camera of Audi lane assist also serves a number of functions in addition to these tasks. It provides imagery for the ACC stop & go, and its data also go into the startup function in slow-moving traffic. The camera also plays an important role in emergency braking initiated by Audi pre sense front and for the continuous headlight range control.

Always informed: the speed limit display
The camera-based system in the Audi A8 not only detects speed-limit signs on the side of the road and their supplemental panel, it also detects temporary speed limits posted on digital displays. It also performs situational analysis if the roads are wet or if speed limits apply only during certain times. It can even consider whether the driver is towing something. Country-specific regulations are incorporated by synchronizing data with the navigation system. The driver can choose between a variety of display options in the instrument cluster and is kept constantly informed of the applicable speed limit.

Long-range vision in the dark: the night vision assistant
Another high-end system in the Audi A8 L is the night vision assistant, which marks the persons detected. The heart of this system is a thermal imaging camera in the single-frame grille. It has a wide, 24-degree angle of view, and its protective window is cleaned when dirty and heated when cold. As a far infrared system (FIR), the camera reacts to the heat radiated by objects. A computer converts the information from the camera into black-and-white images and displays them on the driver information system display.

Far infrared technology has significant strengths compared to competing systems. Independent of driving speed, it can look as far as 300 meters (984.25 ft) ahead, far beyond the range of the high beams, and therefore is not blinded by headlights and similar light sources. Most importantly, it concentrates on that which is most important: animals and people. They are conspicuously bright in the image due to the heat they radiate, whereas the cooler road appears dark.

The image processing software can detect persons at a range of up to 100 meters (328.08 ft). They 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 marked in red and a warning gong sounds. Like every assistance system, the night vision assistant also works within certain, liberal system limitations.

Informative: the parking assist systems
Audi offers a choice of two parking assist systems in the A8 L. The parking system plus (standard in the W12) uses eight ultrasonic sensors to indicate the distance acoustically and graphically on the large onboard display. The front sensors also monitor the starting zone immediately in front of the car for the ACC stop & go when the sedan is creeping along in traffic.

The parking system plus with reversing camera also uses an extremely 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 input and displayed on the MMI operating system monitor. Guidelines and fields show the driver the projected path of the car.

100 control units: the network
The onboard network of the new Audi A8 L is shaped like an H, with the horizontal member located in the vicinity of the rear seat. The seatback forms a protected space into which as many as 15 control units are integrated. A conventional onboard network in a large sedan comprises up to 1,500 individual wires and weighs roughly 50 kilograms (110.23 lb). In the new A8 L, Audi reduced its weight by 8 kilograms (17.64 lb) despite the many new functions. The network comprises a total of seven bus systems and roughly 100 control units.

The electronic nervous system in the new Audi flagship is so complex that it required a new architecture. The A8 L uses the FlexRay bus system, which makes the transmission of data between the individual control units significantly faster and more reliable.

The equipment and data specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.