Audi is a driving force in the area of driver assistance systems. The next step will be systems that assume the task of driving in certain situations if the driver so desires. Audi refers to this as “piloted driving.”
Driver assistance systems of today
From adaptive cruise control with stop & go function to traffic sign recognition, Audi offers an extremely wide range of driver assistance systems across the entire model lineup. The systems are tightly networked, making them intelligent, powerful and versatile.
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, in many models over a speed range from 0 to 250 km/h (0 to 155.34 mph).
Depending on the configuration, ACC stop & go uses one or two radar sensors at the front of the vehicle. They detect the reflections of objects as far as 250 meters (820.21 ft) away from the car. The driver can adjust the distance to the car ahead and the control dynamics in multiple levels. In stop-and-go traffic, the system can brake the car to a complete 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 to resume driving.
Adaptive cruise control with stop & go function interacts closely with other driver assistance systems; it utilizes the data of numerous control units to continuously analyze all of the car’s surroundings. The system uses this broad knowledge base to recognize complex scenarios and offer anticipatory support to the driver. Because it also works together with the optional MMI navigation plus, it knows the course of the selected route and can use this information to regulate the car’s speed.
Audi offers a number of versions of adaptive cruise control for different model series – including without the stop & go function.
Audi active lane assist
Audi active lane assist is available for most models with electromechanical power steering. It uses a camera with an angle of aperture of roughly 40 degrees mounted in front of the rearview mirror to detect lane markings at a range of more than 50 meters (164.04 ft). The camera and software recognize the lane markings and the path of the car. If the car approaches a line without the turn signal being activated, the system helps the driver to steer back into the lane by intervening discretely in the steering.
The driver determines via the MMI system how soon the intervention occurs and whether it should be combined with steering wheel vibration. If the driver opts for early intervention, the system will keep the car in the center of the lane. The camera of the Audi active lane assist provides differentiated information. For example, it can differentiate between the yellow lines in construction zones and white lines.
Audi active lane assist becomes active at a speed of approximately 65 km/h (40.39 mph). It also intervenes if there is a risk of skidding. In this case, it supports correct countersteering by briefly increasing or reducing power steering boost.
Audi side assist
The lane change assistant Audi side assist is available for many Audi models. It monitors traffic behind the car 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 radar sensors in the rear monitor events behind the car at a distance of up to 70 meters (229.66 ft).
If there is a vehicle in the blind spot or rapidly approaching from the rear, a yellow LED indicator in the outside mirror’s housing lights up. The driver sees the LED when checking the mirror. If the driver nevertheless activates the turn signal to change lanes, the indicator become brighter and flashes multiple times. The optical signals are aimed at the driver. Their brightness varies according to the ambient light level and can be set individually using the MMI system.
Night vision assistant
The heart of the night vision assistant is a thermal imaging camera with a 24-degree angle of aperture at the front of the automobile. It works in the far infrared range (FIR) and reacts to the heat radiated by objects in the recorded scene. A computer converts the information from the camera into black and white images and shows them on the driver information system’s central display, if desired.
Far infrared technology can look up to 300 meters (984.25 ft) ahead, far beyond the range of the high beams. It is not affected by glare from headlights or similar light sources. Because of the heat they give off, people and larger wild animals generally appear strikingly bright against the cooler and thus darker background, making them easy to recognize. Within system limits, the image processing software can detect persons at distances up to 90 meters (295.28 ft) and larger wild animals at up to 130 meters (426.51 ft). It looks specifically for characteristics of pedestrians and larger wild animals, such as their contour. It highlights detected persons and animals in yellow on the display.
If the system predicts a hazard because a person is crossing the road in front of the car, for example, the person is marked in red and a warning tone sounds. The driver can also choose to have a warning displayed in the optional head-up display. The brake system is conditioned at the same time. In some models, the pedestrian will be illuminated with three brief flashes of light.
Park assist
The Audi parking systems work with ultrasound. One particularly convenient solution is park assist. It completely takes over the steering when backing into detected parking spaces either parallel or perpendicular to the road. The system finds parking spaces using ultrasound sensors that scan the side of the road in two dimensions while driving at moderate speed When they detect a space of sufficient size, a message appears in the instrument cluster.
If the driver wishes to park in the space, they put the car in reverse with the system active and the park assist system takes over the steering. The driver only has to accelerate, shift gears and brake. The park assist will maneuver forward and back multiple times and also helps when leaving parallel parking spots.
Another technology from Audi is the parking system plus with surround view cameras. Four small cameras – in the Singleframe grille, in the rear and in the housings of the side mirrors – record the car’s immediate surroundings. The driver can call up a variety of perspectives on the large onboard monitor, including a virtual top-down view. At corners or junctions with limited visibility, the system can show cross-traffic in front of or behind the vehicle that the driver cannot see directly.
Camera-based traffic sign recognition
The camera-based traffic sign recognition system shows the driver the detected speed limit in the instrument cluster or the optional head-up display. A camera behind the rearview mirror detects both speed limit signs on the side of the road and digital speed limit indicators. The control unit compares them 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
Audi pre sense is a safety package available in a variety of configurations in numerous model series in addition to the A3 family. Audi pre sense basic analyzes the information provided by the sensors of the electronic stability control (ESC) system. Depending on the situation, the system activates the hazard warning lights and begins to close the windows and the optional sunroof if the sensors report maximum braking or skidding. It also tensions the front seat belts. Small electric motors trigger this tensioning, which is reversible.
The extended versions of this 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 stages of driver support. The first comprises an optical and acoustic warning signal; the second a warning jolt – a brief application of the brakes. If the driver then brakes, the system helps by adjusting the amount of brake pressure required. If the driver does not react, the system initiates partial braking as the third stage. This slows the vehicle with about one-third of the possible braking power. The windows and optional sunroof begin to close, the hazard warning lights are activated and the seat belts are tensioned.
If the car is equipped with the full version of Audi pre sense plus, a fourth stage comes into play: first another round of partial braking at a moderate level, followed by maximum braking, during which the seat belts are fully pretensioned. This occurs shortly before impact, when a collision can no longer be avoided. Audi pre sense plus reduces the vehicle’s speed by up to 40 km/h (24.85 mph) before impact, which mitigates the consequences of the accident.
In some models, Audi pre sense front offers an additional protective function to mitigate or prevent collisions with the car ahead at low speeds. Below 30 km/h (18.64 mph), the car brakes autonomously in a critical situation, regardless of whether the vehicle ahead is moving or stopped. Below 20 km/h (12.43 mph) the new function can generally prevent the accident entirely. In other cases it significantly reduces collision speed and thus the severity of the accident.
Audi pre sense rear uses the Audi side assist sensors and mitigates the consequences of a rear-end collision. Here, too, the system closes the windows and sunroof and tensions the seat belts. If the car has optional front memory seats, they adjust to a position more favorable to passenger safety.
Piloted driving: taking the fun of driving to a whole new dimension
In the near future the driver assistance systems from Audi will be even smarter and more powerful, and many assistive functions will find their way into cars. Audi calls these functions “piloted driving.” The new systems will take over the driving in certain situations, making it more comfortable and safer. Nevertheless, it always remains the driver’s choice to turn over the wheel.
Piloted driving in traffic jams
Piloted driving in traffic jams will take the stress out of driving in slow-moving traffic in the future. At speeds between zero and 60 km/h (37.28 mph), the system takes over the steering. It also accelerates and brakes autonomously. The Audi system for piloted driving in traffic jams continuously assesses the status of the car and its entire surroundings. If the system detects a traffic jam situation (with physical separation of the opposing lane or lanes) at speeds below 60 km/h (37.28 mph), the driver can activate the function. The car then assumes full control. It behaves exactly like Audi ACC stop & go in accelerating and braking; it also reacts cooperatively to cars moving into or out of the lane.
When piloted driving reaches its system limits are reached, such as when the traffic jam dissolves or the end of a divided road is reached, it prompts the driver to take back control.
If the driver does not take back control within five seconds of being prompted, light braking and a more intensive warning are triggered. If the driver fails to react within an additional five seconds, the system establishes a minimal-risk state. The car is braked to a stop and the hazard warning lights are activated. This minimal-risk state is also assumed in the likely event of a technical malfunction. It is important here that there be no possibility of a collision with opposing traffic and that it is possible to a safely come to a complete stop due to the traffic jam situation.
As with Audi adaptive cruise control with stop & go function, a radar system monitors the area in front of the car in a 35-degree field of view and at a distance of up to 250 meters (820.21 ft). A video camera with a wide angle of aperture detects the lane markings as well as pedestrians and objects, such as other vehicles and guard rails. Up to twelve ultrasonic sensors are used to monitor the space near the car.
And now a laser scanner is being used for the first time. It provides highly precise data at a range of up to 80 meters (262.47 ft) Its laser diode emits nearly 100,000 infrared light pulses per second that are invisible to the human eye. The sensor scans a field of view of 140 degrees with a resolution of 0.25 degrees over four different levels. The control unit computes a highly detailed surroundings profile from the light reflections. This profile represents other vehicles as well as guard rails. The key advantages of the laser scanner are:
a) Because of the large angle of aperture, cars entering the lane are detected very early.
b) The laser diode means that it is fully functional in the dark.
c) Its measurement method enables it to detect any objects, even those with a solid pattern or with no visible structure.
Piloted driving for parking at curbside and in garages
Parking in tight quarters is uncomfortable. Narrow parking spaces or garages make it difficult for the driver to get in and out of the car. Thanks to piloted driving from Audi, drivers will be able to operate the car comfortably via the remote key fob or smartphone while standing outside it in front of the garage or a narrow parking space.
The piloted parking function is offered to the driver when the environmental sensors detect a suitable parking space or garage. The driver can now get out and initiate the parking sequence. Upon reaching its parked position, the car shuts off the engine and locks the doors. The driver receives a confirmation message at the end of the process. The push of a button is likewise all that is required to retrieve the car from the garage or parking space.
The so-called “drive switch” (remote key fob or button on the smartphone) plays a key role. The customer must press and hold it continuously for piloted parking to begin. The system also verifies that the remote key fob is in the vicinity of the car (approx. 5 meters [16.40 ft], because the driver would otherwise not be able to monitor the parking process. The car of course stops if the sensors detect an obstacle in the driving corridor. In the event of a system fault, the car immediately brakes to a complete stop
Piloted parking utilizes the same system of sensors as the traffic jam system. Information is also obtained by processing images from the four 360-degree cameras that monitor the surroundings. This additional physical measurement method complements the ultrasonic sensor system.
Driver assistance systems with maximum integration: the central driver assistance control unit (zFAS).
Today’s driver assistance systems are mostly implemented in spatially separate control units. Audi will pursue the revolutionary approach of a central driver assistance domain architecture in the future. All available sensor information will then be compiled in a central control unit (zFAS), enabling the creation of a complete environmental model for the first time ever. This model is used by the classic driver assistance systems. Audi’s piloted driving system, in particular, draws on this redundantly computed environmental information.
The zFAS board exhibits certain design parallels with the latest generation modular infotainment platform. Audi’s strategic development partners also deliver advanced multi-core processors for the zFAS. All together, the processors on the zFAS board have the computing power of the entire electronics architecture of today’s Audi A4. The new board currently has about the same area as a compact laptop computer, and its space requirements will continue to shrink rapidly. The modular concept ensures high scalability and future viability.
Audi has now implemented the research and predevelopment projects in a production-ready architecture, and will introduce it in production models in conjunction with piloted driving before the end of the decade. Audi has once again assumed the leading role. Specific properties of the Audi solution are:
a) Unlike the usual predevelopment projects, this is not a PC implementation, but rather implementation in a production-ready zFAS control unit.
b) The piloted parking and driving functions are combined in one control unit. Because these two customer functions will be merged in the medium term, separation in two control units is undesirable.
c) The central fusion uses all available environmental sensors and thus satisfies the redundancy requirements for automated driving.
d) Specific measures in the architecture and in individual components consider the requirements of functional safety and the relevant standards (ISO 26262).
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.
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