Basic information

Ingolstadt, 2012-03-08

Driver assistance systems of today

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 lines, 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 (155.34 mph).

ACC stop & go employs two rear-mounted radar sensors, which are heated automatically in cold weather. The sensors transmit radar waves at a frequency of 76.5 gigahertz in order to detect objects up to 250 meters (820 feet) ahead of the vehicle. This sensor-based system evaluates the signals and, within system constraints, detects 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, which is a good third of what is possible.

In stop-and-go traffic, ACC stop & go automatically 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. But first the system employs the video camera and radar sensors to check in front of the vehicle. 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. This wealth of information allows the system to recognize complex scenarios and proactively aid the driver. Because it works in conjunction with the navigation system, it knows which route lies ahead and can use this information to control the vehicle’s speed.

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 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 lines – without the stop & go function, too. The individual versions differ slightly in their mode of operation due to the different degrees of networking and configurations.

Audi active lane assist
A very recent addition to Audi’s line-up of assistance systems is Audi active lane assist – available for most model lines which feature electromechanical power steering. At speeds above approx. 60 km/h (37 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 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 camera of Audi active lane assist in the A6 and A7 provides 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 lane change assistant Audi side assist 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 in the rear observe what is happening behind the vehicle to a distance of 70 meters (229.66 ft). Their data are analyzed by a computer.

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 distracting 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. The optical signals are aimed at the driver. Their brightness varies according to the ambient light level and can be set individually via the MMI user terminal.

The 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 registers heat radiated by objects in the field of view. 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 up to 300 meters (984 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. Any person detected is highlighted in yellow on the screen. 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.

Park assist
Audi offers a variety of automatic parking systems for its entire model line-up. They operate by means of either ultrasound or cameras, which display images via 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. The system notifies the driver via a message in the display once the sensors have found a space which is large enough.

If the driver wishes to park in the space offered, he or she shifts into reverse 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 – capture images of the vehicle’s immediate surroundings. The driver can call up a variety of views on the large onboard monitor, including front-camera and rear-camera perspectives as well as a virtual top-down view. The parking system plus with surround view camera also comes in handy when lines of sight are obstructed. Special viewpoints allow it to analyze cross-traffic otherwise invisible to the driver in front of or behind the vehicle.

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 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.

Audi pre sense safety system
Audi pre sense is a technology package for anticipatory safety. It is available in a number of different configurations for larger Audi model models. 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.

This safety system’s configurations 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 warning consists of a visual and audible signal. If the driver does not react, then the system briefly brakes the vehicle – a jolt which serves as the second warning. If the driver begins braking, then the system helps by adjusting the brake pressure so a collision can be avoided.

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: a second 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 shortly 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 models, Audi pre sense front integrates an additional function to protect against imminent rear-end collisions at low speeds. At speeds under 30 km/h (18.64 mph) the function automatically brakes the car in critical situations – with almost 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 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.

The adaptive restraint system
In many models, passengers are protected by the Audi adaptive restraint system, which in some model lines 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 seatbelt force limiters is managed intelligently.

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 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 the 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 remain 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 occur time and again at intersections, with impact speeds typically ranging from 15 to 50 km/h (9.32 to 31.07 mph). Within a mere tenth of a second, seat backs are suddenly moving at 7 to 25 km/h (4.35 to 15.53 mph). 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 as well as the R8 and TT; in all other models, this task is handled by the head airbag system. Covering an area which extends from the A-pillar to the C-pillar, it unfolds like a curtain from the roof frame to the door window sill. Three-point automatic belts with belt tensioners and ISOFIX mountings for child seats round out the safety package.

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.

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