Audi Q5: The Assistance Systems
Intelligent assistance systems are the latest trend in active safety and the brand with the four rings is leading this development from the front. Analyses by the AARU (Audi Accident Research Unit) have shown that distractions, fatigue and poor concentration are responsible for 70 percent of all collisions. This is the starting point for Audi’s assistance systems, which seek to defuse such situations by making driving safer and more relaxed. They are capable of scanning part of the area around the vehicle, then deciding and acting accordingly in the same way as the driver does, only with much greater reliability.
One of these hi-tech systems adopted from the luxury class is ACC, a radar-based adaptive cruise control system. It regulates the speed and the distance from the vehicle in front over a range of 30 to 200 km/h (18.64 to 124.27 mph) and also applies the brakes automatically within certain limits.
The radar sensor, located at the front end of the Audi Q5, contains four transmitters and receivers in its housing. These send out signals with a wavelength of 76.5 Gigahertz at intervals of 100 milliseconds. The signals scan an area 180 meters (590.55 ft) long over an angle of eight degrees. The signals are fed into a computer that is integrated into the Audi Q5’s data bus network and can establish contact with the control units for the engine, the S tronic and the ESP stabilization system within a matter of milliseconds.
The computer constantly analyzes the differences between the successive measurements. Using the Doppler effect and the signal propagation time, it identifies how far away the vehicle in front is, and whether and how that distance is changing. By comparing the signals in the four individual antennas, it also calculates the angle of the vehicle in front in relation to the car’s own direction of travel. It works out the latter from information about road boundaries such as crash barriers, and from various signals supplied by the ESP.
ACC allows the driver to choose between various modes. The time interval from the vehicle in front can be adjusted over four stages and the control response in three stages ranging from comfortable to sporty. ACC speeds up the engine or applies the brakes as necessary in order to maintain the correct speed and distance, with priority given to ride comfort. Deceleration is limited to no more than 3 m/s2 at speeds above 50 km/h (31.07 mph), i.e., one-third of the maximum possible deceleration. To the driver this merely feels like moderate braking.
Warning system: Audi braking guard
In certain situations this automatic braking may nevertheless not be sufficient, for example if the vehicle in front brakes suddenly or the driver is unable to identify the new situation with sufficient speed. In such instances an integral subsidiary function of ACC takes over: Audi braking guard warns the driver in two stages.
The first stage involves acoustic and visual signals. A gong sounds and a red signal lights up in the instrument cluster. Meanwhile the ESP ensures that the brake system is prefilled with hydraulic fluid. If the driver remains passive, the next stage is activated: the acute warning.
This unmistakable jolt is triggered off if the computer establishes that only an immediate response by the driver usually meaning applying the brakes hard will ease the situation.
The form of the acute warning was one of the top priorities in the development of Audi braking guard. The engineers worked through various options in extensive simulations involving test candidates. The warning jolt was the clear winner; it is produced by a rapid buildup of pressure in the brake system and lasts just half a second. It slows the Audi Q5 down by no more than 5 km/h (3.11 mph) to avoid the vehicle behind causing a nose-to-tail collision.
In most of the cases observed during testing, the warning jolt caused drivers who were distracted to look at the road ahead again and step on the brakes. The hydraulic brake assist system converts that pedal action into delay-free hard braking. By prompting the brake system to fill with hydraulic fluid ahead of time, ESP saves 100 to 200 milliseconds an interval that translates into more than seven meters (22.97 ft) of stopping distance at 130 km/h (80.78 mph).
Audi braking guard remains on the lookout even if the driver has deactivated ACC. The early warning, or alternatively the complete function, can however be switched off separately, in accordance with the Audi policy of leaving the driver as much control over the car as they may wish to exercise. For Audi, technology is never just an end in itself, but always at the service of the road user. The aim must always be to reduce the driver’s workload, without absolving them from ultimate responsibility, and certainly without insisting on a certain course of action.
A sidelong glance to the rear: Audi side assist
Rather like ACC, Audi side assist too uses intelligent radar technology. The system warns of hazardous situations when changing lane. Two radar sensors in the rear bumper, operating at a frequency of 24 Gigahertz, scan the area next to and behind the Audi Q5, up to a distance of 50 meters (164.04 ft) from the car.
A high-speed control unit analyzes the raw data. Thanks to its further improved sensors, Audi side assist is already active from a speed as low as 60 km/h (37.28 mph) in other words, at normal speeds for urban expressways; this progress will also become available in other Audi car lines that use the system.
If another vehicle is traveling at a similar speed within the critical range, or is approaching rapidly from behind, a yellow LED display comes on in the left or right exterior mirror housing. Its configuration is deliberately “subliminal”, in other words it is only visible when the driver looks directly at the mirror; it is imperceptible while the driver is looking straight ahead.
The LEDs brighten and begin flashing rapidly for roughly one second if, despite the warning display, the Audi Q5 driver signals a lane change. The flash is practically impossible to overlook because the human eye is extremely sensitive to changes in contrast in the peripheral field of vision. Audi analyzed the display’s effect in detail in exhaustive test series involving drivers of a variety of builds and ages.
The display’s appearance is such that in practice it is only visible to the driver. It must not be visible to vehicles following on behind, to comply with type approval requirements, and should not be visible to the front passenger for psychological reasons. The brightness of the display adapts to the ambient light conditions and can be adjusted from the MMI operating terminal. The Audi side assist system can be deactivated at a switch located near the exterior mirror.
Staying in lane: Audi lane assist
A third technology completes the portfolio of assistance systems in the Audi Q5 Audi lane assist. From a speed of about 65 km/h (40.39 mph), it alerts the driver if they are about to drift out of lane. A small camera above the interior mirror monitors the road ahead of the car, over a field of view 60 meters (195.85 ft) long and about 40 degrees wide. A high-speed computer sharing the same housing detects the road markings.
If the driver approaches one of these lines without indicating, Audi lane assist warns them by causing the steering wheel to vibrate via a motor in one of its spokes; the intensity of this vibration can be set at three different stages via the MMI. The timing of the warning can also be set at three different levels before the wheels have even reached the lines, as soon as they cross them, or based on the system’s adaptive interpretation. Audi lane assist can also be deactivated. A display indicates if it is activated but unable to provide warnings, for instance if the lines are too difficult to discern.
Audi offers three parking assistance systems in the equipment range for the Audi Q5. The classic one is the Audi parking system APS, which emits acoustic signals to indicate how much space there is remaining behind the car. Audi parking system plus comes with front and rear visual displays, as well as a total of eight ultrasonic sensors in the bumpers.
The Audi parking system advanced, which has an integral rearview camera, is the choice for maximum convenience and safety. Incorporated into the tailgate, this extremely light-sensitive camera contains a fish-eye lens providing a generous 130-degree view of the area behind the car. Its rectified images are displayed on the large on-board monitor.
The display includes various guide lines and zones to help the driver position the car correctly when reversing. When reversing into a parking bay at a right angle to the direction of travel the standard mode there are orange lines to indicate the path that the car should follow. For parallel parking, areas shaded blue indicate the space needed for the Q5. They show whether the gap is large enough; red and blue lines assist with the steering and countersteering process.
The camera image also shows the optional trailer tow hitch, so that the Audi Q5 can be reversed up with the hitch exactly beneath the trailer drawbar. Thanks to its ultrasound sensors, the Audi parking system advanced also offers the traditional functions of visual and acoustic parking assistance. The driver can use the MMI controls to switch between the video-camera image, a graphic display and automatic changeover between the two.
The equipment, data and prices stated here refer to the model range offered for sale in Germany. Subject to amendment; errors and omissions excepted.