From adaptive cruise control with stop & go function to speed limit display – Audi offers a broad assortment of assistance systems that make driving even more relaxed and under control. In some of the large model series these systems are networked closely together, which gives them a high level of intelligence, versatility and capability.
Audi adaptive cruise control with stop & go function
The core component of the Audi driver assistance systems is adaptive cruise control (ACC) with stop & go function. The system regulates the vehicle’s speed and distance to the vehicle ahead by autonomously accelerating and braking over a speed range from 0 to 250 km/h (0 to 155.34 mph).
ACC stop & go utilizes two radar sensors mounted at the front of the vehicle, which are automatically heated in cold weather. They emit radar waves at a frequency of 76.5 Gigahertz over a fan-shaped field with an scanning angle of about 40 degrees and range of about 250 meters (820.21 feet). Sensor control units process the signals to detect vehicles ahead in traffic within the system limits.
The driver can influence ACC stop & go functionality by setting the time interval to the vehicle ahead and the type of control system dynamics over several adjustment levels, from sporty to comfortable. The maximum rate of deceleration produced by the system is limited to about 4 m/s² (13.12 ft/s²), which is a good one-third of what is possible.
In stop-and-go traffic, ACC stop & go autonomously slows the car to a stop. After a brief stop, such as at a traffic light, it automatically drives off and follows the vehicle ahead; after a longer stop, the driver must tap the accelerator pedal or briefly activate the control stalk.
Before driving off, the system checks the image data supplied by the video camera mounted near the rearview mirror. It is used to detect potential hazards, such as pedestrians who cross the street at the last second. This is supplemented by detailed information from the parking assistant’s ultrasonic sensors.
Adaptive cruise control with stop & go function interacts closely with other driver assistance systems; it utilizes the data of 27 control units to continuously analyze all of the vehicle’s surroundings. The system uses this broad knowledge base to recognize complex scenarios and offer anticipatory support to the driver. Because it also cooperates with the navigation system, it knows the course of the selected driving route in advance, so it can also compute the driving lanes in curves, for example.
ACC stop & go applies its knowledge in many different situations. Whether it is a matter of quickly passing a car that is making a right turn onto a highway, or whether another vehicle is merging into the vehicle’s lane on the freeway, the system handles the many diverse situations like a skilled driver – with reflection and composure – and this makes driving more fluid and harmonious.
Audi offers a number of versions of adaptive cruise control for different model series – including without the stop & go function. The individual versions differ slightly in their mode of operation due to the different degrees of networking and expansion levels.
Audi active lane assist
One of Audi’s current assistance systems is Audi active lane assist; it is available for most model series that have electromechanical power steering. At speeds above approx. 60 km/h (37.28 mph), it uses a camera mounted in front of the rearview mirror to detect lane markings. The camera observes the road to a distance of over 50 meters (164.04 ft) and a scanning angle of about 40 degrees.
Software detects lane markings and the car’s actual course between them. If the vehicle approaches a line without the turn signal being activated, the system assists the driver in steering back into the lane by a gentle yet perceptible steering intervention in the electromechanical steering system.
The driver uses the MMI to set how soon the intervention should occur and whether it should be combined with vibration feedback in the steering wheel. If the driver opts for early intervention, the system keeps the car more precisely centered in the lane – a function that clearly sets Audi apart from the competition.
The color camera of Audi active lane assist in the A6 and A7 provides highly differentiated information. For example, it can distinguish the yellow lines in construction zones from white lines. Its image data is also used by other assistance systems, including ACC stop & go, speed limit display, the Audi pre sense front safety system and variable headlight range control.
Audi side assist
The Audi side assist lane-change assistant is available for a whole host of Audi models. It monitors traffic behind the vehicle and warns the driver of critical lane changes as necessary.
The system begins to operate at a speed of about 30 km/h (18.64 mph). Two 24 Gigahertz radar sensors at the rear of the vehicle monitor what is happening behind it with a range of up to 70 meters (229.67 feet). A computer evaluates their data.
If they detect another vehicle that is in the critical zone – that is, traveling in the blind spot or quickly approaching from behind – the information stage is activated. A yellow LED indicator lights up in the side mirror housing without disturbing the driver, since the driver only sees it when looking directly at the mirror.
However, if the driver activates the turn signal to change lanes, the indicator becomes brighter and flashes multiple times. This pulsed signal – the warning stage – is very noticeable. In this case, the indicator optics are directed towards the driver. The indicator brightness automatically adjusts for the ambient light conditions, or the driver can individually set its brightness via the MMI operating terminal.
Night vision assistant
The core component of the night vision assistant is a thermal imaging camera located at the front of the vehicle. It has an scanning angle of 24 degrees, its protective window is cleaned by its own washer nozzle, and it is heated in cold weather. As a far infrared system (FIR), the camera reacts to the heat radiated by objects in the recorded scene. A computer converts information from the camera to black-and-white images and displays them on the central display between the instruments.
Far infrared technology can look forward up to 300 meters (984.25 ft) ahead, far beyond the range of the high beams, and it is not affected by glare from headlights or similar light sources. Primarily, it focuses on what 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). In analyzing the data, it specifically seeks out human characteristics, e.g. their contours. Detected persons are highlighted with a yellow marking in the display. If the control unit predicts a hazard, for example because a person is crossing the road in front of the car, the person is marked in red and a warning tone sounds. A warning also appears in the optional head-up display.
The image contrast can be configured individually via the MMI. Like every assistance system, the night vision assistant is also subject to certain system constraints. Highlighting of detected pedestrians is deactivated when the air temperature exceeds 28 degrees Celsius (82 degrees Fahrenheit), for example.
Audi offers a variety of automatic parking systems for its entire model line-up. They either operate with ultrasound or with cameras whose images are displayed on the on-board monitor.
One particularly convenient solution is park assist. When backing into a parking space, it performs all the necessary steering movements – it can handle both parallel parking and parking perpendicular to the street. The system finds a parking space with side-mounted ultrasound sensors that scan the parking spaces at the side of the road in two dimensions while driving at moderate speed. If a space of sufficient size is found, a message appears in the display.
If the driver wishes to park in the space offered, he or she engages reverse gear and the park assist system takes over the steering. The driver now only needs to accelerate, shift gears and brake; visual and acoustic use guidance supports the driver here. When parallel parking, the detected space is large enough if it is about 0.8 meters (2.62 ft) longer than the vehicle. Park assist can perform multi-point parking maneuvers and also offers support in leaving parking spaces.
The latest technology from Audi is the parking system plus with surround view cameras. Four small cameras – in the single-frame grille, at the rear and in both side mirror housings – record images of the vehicle’s immediate surroundings. The driver can easily call up different camera perspectives on the large on-board monitor, including not just front and rear camera views but also a bird’s eye view of the vehicle’s immediate surroundings.
The parking system plus with surround view camera not only helps when maneuvering, but also when exiting driveways with poor visibility. Its special views can show both the zone in front of the vehicle and the zone behind it which the driver can not yet see himself or herself.
Speed limit display
Like all assistance systems from Audi, the speed limit display helps to make the driver’s tasks easier. It shows the driver the detected maximum allowable speed in the instrument cluster or head-up display.
A camera mounted on the windshield behind the rearview mirror serves as the primary sensor. Within system constraints, it detects speed limit signs posted on the side of the road, as well as digital speed signs.
The detected traffic signs are compared with data stored in the navigation system, maximum allowable speeds for the particular country and vehicle information, e.g. whether the wipers are on, and the current clock time.
Audi pre sense safety system
Audi pre sense is a technology package for anticipatory safety. It is available in a number of different expansion levels in the larger Audi model series.
In the standard version – Audi pre sense basic – the system evaluates information from the ESP sensors. If they signal that full braking or skidding is occurring, the control unit intervenes. Depending on the situation, it might activate the hazard warning lights and begin to close the side windows and sunroof; it also pretensions the front seat belts. This pretensioning process, which is initiated by small electric motors, is reversible. If an accident does not occur, the seat belts are untensioned again.
The expansion levels of the new safety system are: Audi pre sense front, Audi pre sense rear and Audi pre sense plus. They work closely together with the Audi adaptive cruise control with stop & go function and Audi side assist driver assistance systems.
Audi pre sense front monitors traffic in front of the car for potential collision hazards. The system provides multiple levels of driver support. The first is a warning signal, and the second is a warning jolt caused by a brief braking pulse. Now, all the driver needs to do is press the brake pedal, and brake assist initiates braking. An avoidance maneuver – often the better solution – would also still be possible at this time.
Should the driver remain passive, the third stage follows – partial braking. This decelerates the vehicle with about 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 pretensioned in this case.
If the car has the full version of Audi pre sense plus, a fourth stage comes into play: first another round of partial braking, but this time at a moderate level, followed by maximum braking, during which the seat belts are fully pretensioned.
This occurs about half a second before impact, when a collision cannot be avoided any longer. Audi pre sense plus helps to reduce the vehicle’s speed by up to 40 km/h (24.85 mph) before impact, which reduces accident severity.
On some Audi models, Audi pre sense front integrates an additional function to protect against imminent rear-end collisions in the lower speed range. At speeds under 30 km/h (18.64 mph) the function automatically brakes the car – with full braking force, if necessary – regardless of whether the vehicle in front is moving or stationary. At speeds under 20 km/h (12.43 mph) the new function can often prevent an accident entirely. In other cases, it significantly reduces the vehicle’s speed at impact.
The Audi pre sense rear system utilizes the Audi side assist sensors and reduces the severity of a rear-end collision. Here, too, it closes the windows and sunroof and pretensions the seat belts. If the car has optional front memory seats, they adjust to a more favorable position for passenger safety.
Adaptive restraint system
In many models, passengers are protected by the Audi adaptive restraint system, which in some model series is networked with the anticipatory safety system Audi pre sense. It provides better protection for passengers of different heights than conventional systems, because the interplay of airbags and seat belt force limiters is managed intelligently.
Sensors on the front seat rails detect how far forward or back a seat is positioned. Because the control unit then knows the approximate position of the passenger relative to the seat, it can optimize use of the distance over which the upper body is decelerated by the seat belt and the airbag. Together with Audi pre sense, it reduces this distance by several centimeters because the belts are pretensioned before a crash occurs.
If a passenger is sitting close to an airbag, after the airbag inflates a portion of the air is quickly expelled via valves so that the airbag restrains the head and chest more gently. In other cases, the valves stay closed longer. The variable belt force limiters are also designed to be adaptive.
They control belt tension to keep chest loads as low as possible. Loads on the feet and legs are reduced by bracing structures, energy-absorbing pads and crash-optimized pedals.
The structural design of the seats and head restraints is an important safety feature, especially in the case of a rear-end collision. Such accidents often happen at traffic lights, usually at impact speeds between 15 and 50 km/h (9.32 and 31.07 mph). When this occurs, the seatback is accelerated to between 7 and 25 km/h (4.35 and 15.53 mph) within just a tenth of a second. The integral head restraint system, which is standard in every Audi model, counteracts the risk of whiplash injuries here.
All Audi models are equipped with either two or four side airbags to support the pelvis and chest of occupants in the event of a side impact. The side airbags also protect the head in convertibles and in the R8 and TT. In all other models, this task is handled by the head airbag system. It covers an area extending from the A- to the C-pillars, and it unfolds like a curtain from the roof frame to the door window sill. Three-point automatic seat belts with belt tensioners and Isofix mountings for child seats round out the safety package.
Driver assistance systems of tomorrow
Driver assistance systems that Audi is developing for the near future will be smarter, more versatile and more capable than today’s solutions. Although they do not detract from the responsibility of the person at the wheel, they will make driving even easier and more enjoyable.
Traffic jam assistant
The traffic jam assistant, a visionary technology from Audi, can relieve the driver at times when driving is not much fun, such as in congested traffic. At speeds between zero and 60 km/h (37.28 mph), the system helps to steer the car within certain constraints. It also accelerates and brakes autonomously. The traffic jam assistant can be used on expressways or in cities, provided that the course of the road is not too complex.
The traffic jam assistant is based on the functionality of adaptive cruise control with stop & go, extended by adding the new component of lateral guidance. Two radar sensors monitor fan-shaped fields, each with a 21 degree scanning angle and up to 250 meters (820.21 ft) long.
A wide-angle video camera monitors the lane markings, and it can also detect objects such as other vehicles, pedestrians and guardrails. Eight ultrasonic sensors monitor zones directly in front of the car and at its corners.
When ACC stop & go is turned on, the traffic jam assistant continuously analyzes the speed of the car and that of surrounding vehicles. If it detects a traffic jam from the data at speeds below 60 km/h, the driver can activate its functionality by pressing a button.
The corridor within which the traffic jam assistant drives the car is significantly wider than the lane between the lines; this allows for a certain offset relative to the car ahead. If it is necessary to make room for emergency vehicles or maneuver around an obstacle, the system follows the car ahead. The radar sensors not only detect the vehicle ahead, but also other vehicles in front of it. This lets the system compute a caravan lane. The traffic jam assistant behaves exactly like Audi ACC stop & go in accelerating and braking; it also reacts to cars moving into or out of the lane.
Audi pre sense city
Today, many cars from Audi can already slow themselves down over the last few meters before impact in case of an imminent collision, when the driver is no longer able to intervene. Audi brand engineers are further developing these functions.
Automatic maximum braking initiated by the vehicle in urban traffic, also known as Audi pre sense city, is based on a new type of sensor technology, and Audi played a major role in its fundamental development. The PMD sensor (PMD: photo mix detector) is a small chip that can measure distances in three dimensions, and it can do so more precisely than conventional sensors. It can detect both moving and stationary targets, and it can actively operate under conditions of darkness, rain or bright sunshine.
If there is an imminent collision within a speed range up to 65 km/h (40.39 mph), Audi pre sense city warns the driver by briefly pulsing the brakes. If the driver does not react, the system applies full braking force about one second before impact. This can reduce the speed at impact by up to 30 km/h (18.64 mph).
Another important function is anticipatory protection of pedestrians, which the PMD sensor can detect at distances of up to 20 meters (65.62 ft). If it signals a potentially hazardous situation, the system decides whether emergency braking is necessary. If so, full braking would ideally begin about one second before impact in this case too. The maximum possible speed reduction of 30 km/h (18.64 mph) is sometimes able to bring the car to a full stop in time to prevent a collision. The anticipatory pre sense technology offers very good protection for bicyclists as well.
Active emergency braking
Audi is developing another expansion stage of the pre sense system that can perform automatic full braking at speeds over 65 km/h (40.39 mph). Its core component is a laser scanner – a technology whose strengths lie in long-distance scanning, a high level of precision and a large scanning angle. The laser also scans zones to the sides in front of the car, which lets it detect construction activities on the edge of the road. If there is an obstacle in front of the vehicle, such as the end of a traffic jam, the system evaluates whether the driver can still take evasive action.
If evasive action is no longer possible, a timely warning is provided, and automatic full braking is initiated as necessary. This strategy achieves deceleration from relatively high vehicle speeds, which in turn can significantly reduce accident severity. It can also help in situations where the driver cannot react due to a medical emergency. In some scenarios, it is conceivable that the system’s braking interventions could prevent accidents, even from high initial speeds.
Active seatbelt buckle
Audi is continually working to enhance its restraint systems. Another potential future innovation: active seatbelt buckles for rear passengers that are moved by small electric motors. When a rear door is opened, the active seatbelt buckle would move upward several centimeters to make it easier for passengers to buckle up. Then it would return to its rest position. In case of an imminent collision, the buckle would be moved downward somewhat to pretension the seat belt; this process would be reversible.
As a general practice, Audi will be networking the adaptive restraint system more intensively with new assistance technologies. Forward-looking sensors such as PMD diodes can usually identify an imminent collision a few seconds before it occurs while also estimating the speed and size of the other vehicle. The adaptive belt force limiters and adaptive front airbags are triggered based on this information.
The intersection assistant aims to help to avoid collisions, or reduce their severity, where lanes merge and at intersections. Two radar sensors and a wide-angle video camera scan zones to the front and sides of the vehicle. The radar-based data takes the lead here, while the camera data is used for adjustments. If the sensors detect a vehicle approaching from the side and view the situation as critical, the system warns and informs the driver over a number of stages.
Audi is exploring a second variant, which is an extension of the sensor-supported intersection assistant. It is based on car-to-X communication and utilizes the radio contact between the two vehicles that could potentially become involved in an accident. At intersections identified as accident hot spots, it is conceivable that a modem could be used to incorporate the state of the traffic light in accident avoidance. Car-to-X technology exhibits a number of strengths. For one, it can operate at intersections where the line of sight of sensors fitted on the vehicle may be blocked. It is also effective over long distances and transmits vehicle-specific information. This information could be used to adapt airbag deployment to the mass of the other accident vehicle, for example.
When parking in narrow spaces that are perpendicular to the driving lane, or in garages in which there are not just cars but also bicycles and other items – parking is often so tight that the driver must struggle to get out of the car afterwards. The park pilot , a further technological vision from Audi, could solve these problems.
Utilizing technology that is installed in an Audi prototype, the driver can exit the vehicle in front of the garage and instruct it to autonomously park itself via the remote key fob or by smartphone. With the help of its ultrasonic sensors, the car drives into the parking space or garage, stopping immediately if it detects an obstacle.
Upon reaching its final parked position, it shuts off the engine, deactivates the ignition and locks the doors. Finally, it sends a confirmation to the driver.
Warning system for backing out of parking spaces
Driving in reverse out of a parking space at right angles to the road can often be a tricky maneuver. When the delivery van parked next to him is blocking the driver’s view of the traffic passing at right angles behind his own car, he or she must cautiously edge the car out into the street. A warning system for backing out of parking spaces – another future solution from Audi – makes this process easier.
The system utilizes the two Audi side assist radar sensors at the rear of the vehicle. They measure and interpret the distance, speed and anticipated driving paths of detected vehicles in cross traffic. Predicted collision risks are displayed.
Warning when opening the door
The exit warning system also utilizes the radar sensors of Audi side assist. This system offers excellent assistance when exiting the vehicle on busy roads. When the driver or a passenger starts to open the door, the sensors check whether another vehicle or bicyclist is approaching from the rear at a hazardous distance and a critical speed. If it is not advisable to open the door at that moment, the driver or passenger is provided with a warning.
Future car-to-X communication also harbors great potential in the area of lighting. One of many conceivable scenarios is when the car is halted at a red traffic light or in a traffic jam. During this period the headlights are dimmed to a large extent or switched off completely, to save energy and avoid imposing a possible burden on other road users.
When cars are able to exchange data directly, they can coordinate the brightness of their headlights, for instance in dense stop-and-go traffic or at intersections. The road can always be effectively illuminated without dazzling the drivers.
The equipment, data and prices specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.