From adaptive cruise control with stop & go function to the speed limit display, Audi has a broad range of assistance systems in its portfolio that make driving more convenient and controlled. In some of the large model series, they are tightly networked, which imbues them with a high degree of intelligence, versatility and capability.
adaptive cruise control with stop & go function
The central element of the Audi driver assistance systems is the adaptive cruise control with stop & go function, an automatic interval-maintenance system. The system regulates the speed and the interval to the vehicle ahead by automatically accelerating and braking in a speed range of 0 to 250 km/h (0 – 155.34 mph).
The ACC stop & go uses two radar sensors installed at the front of the vehicle which are automatically heated when it is cold. They transmit radar waves at a frequency of 76.5 gigahertz covering a roughly 40 degree wedge-shaped field measuring approx. 250 meters (820 ft) in length. Sensor control units process the signals and thus detect vehicles ahead.
The driver can influence the function of the ACC stop & go; the interval to the vehicle ahead and the control system dynamics are adjustable in several steps, from sporty to comfortable. The maximum rate of deceleration which the system allows is limited to roughly 4 m/s² (13.12 ft/s2), which is a good third of what is possible.
In stop-and-go traffic, the ACC stop & go automatically slows the car to a stop. After a brief stop, at traffic lights for example, the vehicle moves off again automatically and follows the vehicle ahead. After a longer stop, the driver must tap the accelerator or the control lever. Before setting off, the system checks the image data supplied by the video camera in the region of the interior rearview mirror. In this way it can detect possible dangers, such as pedestrians wanting to cross the road at the last minute. The parking system’s ultrasonic sensors provide additional detailed information to monitor pulling away.
The adaptive cruise control with stop & go function interacts closely with other driver assistance systems; it uses the data from 27 control units to continuously analyze the vehicle’s surroundings. This expanse of knowledge enables the system to recognize complex scenarios and predictively support the driver. Because it also cooperates with the navigation system, it knows the course of the selected route in advance and can also compute the lane in curves, for example.
The ACC stop & go uses its 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 vehicle on the highway, the system handles many situations with the reflection and composure of a skilled driver, making driving even more fluid and harmonious.
Audi offers the adaptive cruise control in a number of different versions, including without stop & go function, depending on the model series. The function of the individual versions varies slightly due to the different degrees of networking and the expansion levels.
Audi active lane assist
One of the current Audi assistance systems is Audi active lane assist which is available for most model series with electromechanical power steering. At speeds above around 60 km/h (37.28 mph), it uses a camera mounted in front of the rearview mirror to detect the lane markings. It observes the road to a distance of more than 50 meters (164.04 ft) and a coverage angle of roughly 40 degrees. It delivers 25 high-definition images per second.
Software detects the lane markings and the course the car is following between them. If the vehicle approaches a line without the turn signal being activated, the system helps the driver to steer back into the lane by intervening gently, but perceptibly, in the electromechanical steering. The driver uses the MMI to determine how soon the intervention occurs and whether it should be combined with steering wheel vibration. If the driver opts for early intervention, the system keeps the car in the center of the lane – a function that sets Audi clearly apart from the competition.
The color camera of the Audi active lane assist in the A6 and A7 provides highly differentiated information. For example, it can differentiate between the yellow lines in construction zones and white lines. Its image data are also used by additional assistance systems, including the ACC stop & go, the speed limit display, the safety system Audi pre sense front and the variable headlight range control.
Audi side assist
The lane change assistant Audi side assist is available for a whole host of Audi models. It monitors the traffic behind the vehicle and warns the driver as necessary prior to critical lane changes.
The system becomes active when a defined speed is reached. Two 24 gigahertz radar sensors in the rear monitor what is happening behind the vehicle to a distance of 70 meters (229.66 ft). Their data are analyzed by a computer.
When they detect another vehicle in the critical zone – riding in the blind spot or approaching rapidly from the rear – the so-called information stage is activated. A yellow LED indicator lights up dimly in the housing of the driver’s exterior mirror, without disturbing the driver. The driver sees it only when looking directly into the mirror.
If the driver nevertheless activates the turn signal to change lanes, the indicator becomes brighter and flashes multiple times. This signal – the warning stage – is clearly perceptible. The optical signal is directed at the driver. The signal’s brightness varies with the ambient light and can also be customized via the MMI operating terminal.
The night vision assistant
The heart of the night vision assistant is a thermal imagin camera located at the front of the vehicle. It has an angle of view of 24 degrees, and its protective window is cleaned by a separate nozzle and heated when cold. As a far infrared system (FIR), the camera reacts to the heat radiated by objects in the recorded scene. 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 far infrared technology can look up to 300 meters (984.25 ft) ahead, far beyond the range of the high beams, and is not blinded by headlights and similar light sources. Most importantly, it concentrates on that which is most important: 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 surroundings appear dark.
The image processing software can detect persons at a range of approximately 100 meters (328.08 ft). When analyzing the data, it specifically seeks out human contours and objects that are bright and round – their heads, in other words. Detected persons are highlighted with a yellow marking on the display. If the control unit predicts 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. A warning also appears in the optional head-up display.
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 system limitations. Highlighting of detected pedestrians is switched off at air temperatures above 28 degrees Celsius (82 degrees Fahrenheit), for example.
Audi offers a variety of different parking systems for its complete model line-up. They use ultrasound, acoustic and optical signals, or a rearview camera whose images are displayed on the on-board monitor. One particularly convenient solution is park assist. When reversing into a parking space, park assist performs all the necessary steering movements – this applies equally to both parallel and end-on parking spaces. The system locates parking spaces using side-mounted ultrasound sensors that scan the parking spaces on the side of the road in two dimensions while driving at moderate speed. A notification appears in the display when the system finds a suitable spot.
If the driver wants to park in the space and puts the vehicle into reverse, the park assist system is activated and performs all necessary steering movements with the aid of the electromechanical steering. The driver must continue to accelerate, shift gears and brake. Visual and acoustic signals provide support. When parallel parking, it suffices when the space is roughly 0.8 meters (2.62 ft) longer than the vehicle. If necessary, the park assist will make multiple maneuvers, forwards and backwards. The system provides similar assistance when leaving parking spaces.
The latest Audi technology is the parking system plus with surround view camera. Four small cameras – in the single-frame grille, in the rear and in the housings of the side mirrors – record images of the vehicle’s immediate surroundings.
The driver can call up a variety of views on the large onboard monitor, including a top-down view of the vehicle’s direct surroundings. The parking system plus with surround view camera increases safety not only when maneuvering, but also in narrow exits. Its special views can show the area both in front of and behind the car and allow the driver to see cross-traffic in front of or behind the vehicle.
The speed limit display
Like all assistance systems from Audi, the purpose of the speed limit display is to reduce the burden on the driver. It shows the driver the current maximum permissible speed in the instrument cluster or on the optional head-up display.
A camera mounted on the windshield behind the rearview mirror serves as the central sensor. Within the limits of the system, it detects speed limit signs erected on the side of the road, as well as digital speed limit indicators and pictogram-based supplemental signs. The detected traffic signs are analyzed and compared against the data from the navigation systems, the maximum permissible speeds in the respective country and information from the vehicle, such as whether the wipers are on and the current time.
The Audi pre sense safety system
Audi pre sense is a technology package for predictive safety. It is available in a number of different expanded levels in the larger Audi model series.
In the standard variant – Audi pre sense basic – the system analyzes the information from the ESP sensors. When they signal maximum brake application or skidding, the control unit intervenes. Depending on the situation, it activates the hazard warning lights and begins to close the side windows and the sunroof; and it tensions the belts at the front seats. This tensioning process, which is reversible, is triggered by small electric motors. If an accident does not occur, the belts are released again.
The expanded levels of the new safety system are called Audi pre sense front, Audi pre sense rear, and Audi pre sense plus. They work closely together with the driver assistance systems adaptive cruise control with stop & go function and Audi side assist.
Audi pre sense front monitors the traffic in front of the automobile for potential collision hazards. The system provides multiple levels of driver support.
The first is a warning signal, and the second a warning jerk caused by brief braking. If the driver now simply places his or her foot on the brake, the brake assist initiates deceleration. Even an avoidance maneuver – often the better solution – would still be possible at this time.
Should the driver remain passive, the third stage follows – partial braking. The vehicle is slowed with roughly one-third of the possible pedal force. The windows and sunroof begin to close, and the hazard warning lights are activated. The seat belt is also tensioned in this case.
If the full version of the Audi pre sense plus is on board, a fourth stage comes into play: first another round of partial braking, but now at a moderate level, followed by maximum braking, during which the belts are pulled fully taut. This occurs about half a second before impact, at which point a collision can no longer be avoided. Audi pre sense plus helps to reduce the vehicle’s speed by up to 40 km/h (24.85 mph) before the crash and thus to mitigate the consequences of the accident.
On some Audi models, pre sense front incorporates an additional function to protect against impending rear-end collisions in the lower speed range. At speeds under 30 km/h (18.64 mph) the function automatically decelerates the car if necessary with full force – regardless of whether the vehicle in front is moving or stationary. Under 20 km/h (12.43 mph) the new function can often prevent the accident entirely. In other cases it significantly reduces collision speed.
The Audi pre sense rear system uses the Audi side assist sensors and mitigates the consequences of a rear-end collision. Here, too, it closes the windows and sunroof and tensions the seat belts. If the optional front memory seats are on board, they move into a better position for the passengers.
The adaptive restraint system
Passengers in many models are protected by the Audi adaptive restraint system, which in some model series is networked with the predictive safety system Audi pre sense.
The adaptive restraint system intelligently manages the interplay between the airbags and the belt force limiters to protect passengers of different heights more effectively than conventional systems. Sensors on the front seat rails detect how far forward or back the seat is positioned. Because the control unit then knows the approximate position of the passenger, it can ensure that better use is made of the distance over which the upper body is slowed by the belt and the airbag. Together with Audi pre sense, it reduces this distance by several centimeters because the belts are tensioned before the crash occurs.
If a passenger is sitting close to an airbag, a portion of the air is quickly expelled via valves after the airbag inflates so that the head and chest are gathered in more gently by the airbag. In other cases the valves remain closed longer. The variable belt force limiters are also designed to be adaptive. They control belt tension so that the load on the chest remains as low as possible. Bracing structures, energy-absorbing pads and crash-optimized pedals reduces loads on the feet and legs.
The structural design of the seats and headrests is an important element of safety design, especially in the case of a rear-end collision. These types of accidents frequently occur at traffic lights, usually with impact speeds between 15 and 50 km/h (9.32 and 31.07 mph). In these collisions, the seat back is accelerated to between 7 and 25 km/h (4.35 and 15.53 mph) within a tenth of a second. The integral head restraint system, which is standard in every Audi model, acts here to counter the risk of whiplash injuries.
All Audi models are equipped with either two or four side airbags to support the hips and chest of the occupants in the event of a side-impact collision. In open-topped vehicles, in the R8 and in the TT, the side airbags also protect the head. In all other models, this function is provided by the head airbag system.
It spans the area from the A- to the C-pillars and opens like a curtain from the roof frame to the door sill. Three-point automatic belts with belt tensioners and Isofix mountings for child seats round out the safety package.
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.