Here's a bit more information about the ADR system. The source of the text and photos is a press release from VW (posted at German Car Fans .com), dated November of 2002. I believe that ADR will be available quite soon (perhaps in the next 90 days) as an option for North American cars. I'm not sure if it can be retrofitted to an existing car by an enthusiast or not, but eventually I will try to find out.
The innovative Automatic Distance Regulation (ADR) system uses radar to detect vehicles ahead
Speed and distance controlled with the left thumb
Optional ADR adds an automatic braking and accelerating function to the standard cruise control
ADR makes the journey far more relaxed: the driver senses directly that the car is performing various dynamic driving processes itself
Wolfsburg. The Volkswagen Phaeton is one of the most innovative luxury saloon cars available anywhere in the world. Technical highlights such as its 4-zone Climatronic air conditioning, air suspension with controlled damping and the progressive Automatic Distance Regulation (ADR) system, an optional extra, set the standards in this automobile-market segment. This applies to ADR in particular: it transforms the previous style of travel into a new dimension of relaxed convenience. More than was ever possible until now, the driver can sense how the car is performing various dynamic processes on its own initiative.
The automatic distance regulating system uses radar, and takes over precisely where the conventional cruise control (GRA, standard on the Phaeton) calls for the driver to take action: when the car has to be braked or accelerated. If a Phaeton equipped with ADR approaches the vehicle ahead too closely because this is being braked or simply driven more slowly, Volkswagen’s new luxury saloon model reduces its own speed automatically by the necessary amount. The driver sees a signal on the central information display between the speedometer and the revolution counter as an indication that this regulating process is in progress. If the preceding vehicle then speeds up again or the Phaeton’s driver changes to an empty traffic lane, the system accelerates the car automatically back up to the previously selected cruising speed.
Self-explanatory controls on the multifunctional steering wheel
The ADR controls have been designed for exceptional ease of operation and reliability, and are self-explanatory. All the main controls are on the multifunctional steering wheel, which is a standard equipment item. An ‘ON/OFF’ switch activates the ADR and a ‘SET’ button accepts the speed at which the car is travelling as the desired cruising speed. The central information display in front of the driver then shows a stylised section of road with a virtual preceding vehicle and an icon to indicate the system’s functional status. The speed can be varied by the cruise control buttons on the steering wheel.
An innovation has been introduced here too: on conventional systems the car first has to be accelerated with the pedal or by holding the ‘SET’ lever until the desired cruising speed is reached. This method can be adopted by the Phaeton’s driver, but it can also select the desired road speed in 10-km/h steps, up to a limit of 180 km/h. The speed selected but not yet reached is marked on the speedometer dial by a red light-emitting diode above the numerals on the scale and shown on the information display.
The ADR’s distance margin and response dynamic can be varied individually
Within predetermined ranges the driver can also vary the minimum distance from the vehicle ahead and the dynamic response of the ADR system. A drum-type switch on the multifunctional steering wheel selects one of a maximum of seven positions, which are shown graphically on the information display. The settings 1 to 7 represent the elapsed time before the Phaeton reacts to the presence of a preceding vehicle. In position 1 the Phaeton is braked later and, when the road is clear, accelerates more rapidly. In position 7 it brakes very early and accelerates less rapidly.
Settings 1 to 5 are intended for normal driving on dedicated highways; the Phaeton then responds in accordance with the traffic flow and accelerates briskly at the rate the driver prefers when it is steered into a free lane. For long journeys on motorways or similar main roads, settings 3 and 4 are ideal. The last two settings (6 and 7) are intended primarily for ordinary main roads. In setting 7, the distance to the vehicle in front in metres corresponds to the Phaeton’s speed in kilometres an hour: 100 km/h are equivalent to a gap of 100 metres. This setting makes overland journeys very relaxed. If urgent action on the driver’s part nevertheless becomes necessary (for instance if a panic brake application is made), the system provides an audible and visual warning.
The radar system scans the road continuously for 180 metres ahead of the car
Within an angle of 11.5 degrees and for a distance of approximately 180 metres, the ADR detects all vehicles moving in the same direction. The system can be activated at any road speed between 30 and 180 km/h. Above and below this speed range the ADR is de-activated as a safety precaution. The driver can also switch the ADR off by pressing the brake pedal or using the ‘CANCEL’ switch on the steering wheel. If the ‘RES’ (‘RESUME’) button is pressed later during the same journey, the automatic mode and the previously memorised settings are restored.
The complete Automatic Distance Regulation system consists of the ADR control unit in the radar sensor housing, an active brake booster servo (BKV) and the servo control unit. The radar sensor at the front of the car transmits signals in the 76 to 77 GHz range. Since the system is networked with the ESP, it is supplied with information on the Phaeton’s road speed and yaw rate and uses these parameters as well when determining the desired speed change.
The system is networked by means of the driveline CAN bus, so that the ideal engine torque can be sensed. The CAN bus line is also used to link it to the control units for the active brake booster servo and the automatic transmission, and to the central instrument cluster in front of the driver. The ‘Comfort’ CAN, the CAN gateway in the instrument cluster and the driveline CAN are used to connect the controls on the multifunctional steering wheel to the ADR control unit.
ADR optimises journey refinement
Naturally the ADR does not absolve the driver from the responsibility of concentrating on the traffic flow and reacting defensively. What it does is to support the driver in responding particularly effectively to changes in the traffic pattern. Automatic distance regulation helps to avoid driving too close to the vehicle in front in all normal traffic situations and warns the driver whenever action has to be taken. These features of the system can only be regarded as a fundamental step forward in personal driving safety, comparable to the ESP which also helps to prevent accidents from occurring in extreme situations. ADR automatically promotes a defensive style of driving and prompt responses when called for.