Autonomous cruise control system

An Active Cruise Control is a speed control system in motor vehicles, the distance to a preceding vehicle includes an additional feedback and manipulated variables in the scheme.

In the international automotive industry, the English term Adaptive Cruise Control has been established ( in German: Adaptive Cruise Control ), abbreviated ACC.

The system is also called an automatic distance control (ADC ), which still can spread other names, as automotive manufacturers have their systems are always available individually name, to distinguish themselves better.


In an adaptive cruise control, the position and the speed of the preceding vehicle is determined with a sensor and adjusting the speed and the distance of the following vehicle equipped with this system in accordance with an adaptive braking and engine operation ( the longitudinal control). For measuring the distance in the today's vehicles, primarily radar sensors are used. There are also lidar systems, but currently have too high disorders in restrictive view weather conditions. However advantage of the lidar systems is the significantly lower price.

The radar systems operate with an output of about 10 mW. This power is so low that no health effects are expected. The lidar systems operate with no visible light and a comparatively low power, eye safe (laser class 1M).

The approved for this application radar frequency is in the range 76-77 GHz, corresponding to a wavelength of approximately 4 mm (see a millimeter wave). New developments also access the frequency range from 24 GHz since these systems can be produced cheaper and thus also allow the introduction of these systems in the compact class. The laser systems operating in the infrared range.

Are used Abstandsregeltempomaten majority in vehicles with automatic transmissions, since the gear change is performed here independently from the transmission. In hand controls the driver is prompted by a flashing display to switch.

Primary goal is to increase comfort and relief of the concentration for the driver on long highway trips, but also in the little liquid city traffic. Secondary, the security gain is pursued:

  • Simple systems allow a visual and acoustic warning function for the driver and a max. Delay in the braking action up to 25 % of max. possible delay. The value is limited in order to minimize the effect of false detections (in accordance with ISO 15622 - but no legal requirement ).
  • Advanced systems also cause the brake system from a possibly following emergency braking with the aim to shorten the stopping distance.
  • Future systems perform autonomous emergency braking to a stop. They are based on radar and camera technology coupled with high-performance computers danger. A further step will be the automatic dodging and avoiding obstacles.

Some manufacturers now offer in addition a "follow -to -stop " function of following a preceding vehicle to a standstill. In contrast to the stop-and -go system the vehicle at follow -to -stop does not move back automatically. In the stop-and- go function independent start after a brief halt, or fahrergetriggertes restart is possible (after confirmation by the driver pressing the accelerator or the operation of the operating lever ) can accelerate up to the speed set by the driver again. For this purpose, sometimes additional sensors are used for close range. This function is the comfort of the driver gain in cities and in the traffic jam on the highway.

Driving safety

Impairment of driving ability and attention of the driver has not been established, however, a risk compensation is concern over again. By relieving in routine tasks ( Continuous checking of the speedometer, acceleration and braking ), the driver may be less fatigued and can then better concentrate on the traffic.

Adaptive cruise control with different manufacturers

Audi, Bentley and VW

Since 2002, Audi and VW offer initially in their upper class models A8 and Phaeton adaptive cruise control on. Since then, several revised versions were launched:

  • ACC of the first generation (active from 30 to 180 km / h): 2002 onwards in the A8 and Phaeton
  • Second generation (active from 30 to 200 km / h): from 2004 Audi A6 C6
  • Third generation (active 30-210 km / h and if necessary a preparation of brake system for emergency braking ): since 2005 the VW Passat B6
  • Fourth generation (active from 0 to 200 km / h): Warning by " environment observation " of a hazardous condition by several short, autonomous braking jerks: from 2006 in the Audi Q7 and VW Touareg and since 2007 also in the VW Phaeton, the new Audi A4 B8 ( control range in A4 B8 and A5 only from 30 to 200 km / h) as well as in the new VW Passat CC.
  • An ACC was also announced for the Golf VI. For unknown reasons, the project was discontinued.
  • The fourth-generation system was taken from the VW Phaeton and is offered as an option in the Bentley Continental GT models, Flying Spur and soon also in the GTC since 2007.
  • Fifth and sixth generation (active from 0 to 250 km / h): from 2010 in the A8. ACC with Stop & Go function including Audi pre sense. Uses more radar sensors, a video camera and the parking sensors. In slow-moving traffic or in traffic it regulates braking and start-up. The system extends the warning function of the fourth generation. In conjunction with the radar sensors of the lane change assistant is introduced an autonomous full braking, to reduce the severity of the impact as much as possible in situations where a collision is unavoidable.
  • For the Golf VII ACC is optionally available with stop & go function and a built- City Emergency Braking Assist and front.

Audi and Volkswagen called the ACC system with adaptive cruise control. In the house Volkswagen this system was offered earlier by the term automatic distance control.


BMW refers to the ACC system as Active Cruise Control. Not to be confused with the hotel's Adaptive Drive, an active anti-roll system.

The first generation was introduced in April 2000 in the 7-series ( E38 ). Three radar beams to measure a moving angle of 8 ° to a distance of max. 150 m from. Radar beams and evaluation including longitudinal control are integrated in the ACC sensor. The second generation was introduced with the 6-series ( E63/E64 ) in 2004. An enhanced radar sensor measures with now four radar beams from a moving angle of 16 °. In addition, information from the navigation system on road type and course are included with. Thus, the ACC control behaves forward-looking and thus more comfortable.

In March 2007, the Active Cruise Control has been added to the stop-and- go function in the 5-Series ( E60/E61 ). The system is active from 0-180 km / h in congestion situations, it can automatically follow the traffic and possibly slow down to a stop. Within three seconds of stopping automatically or after confirmation by the driver, the vehicle starts up again. BMW uses a security function iBrake. In dangerous situations, the activation thresholds of the Brake Assistant are lowered depending on the situation, pre-filled the brake circuits and pads created imperceptibly to the brake discs and thus preparing the braking system for emergency braking by the driver may have to execute. , The maximum possible delay in the braking action is 40 % of maximum braking force.


Cadillac offered since 2005 optional in the Cadillac STS under the name Adaptive Cruise Control an adaptive cruise control on, which was available as already in the roadster XLR and also in turn, belongs to the newer models SRX, ATS and XTS, among other driving assistance systems for optional equipment.


From the summer of 2007, a lidarbasiertes ACC system from Hella is offered on the list of extras in the house for the Chrysler 300C. This is only available for the SRT8 6.1 engine.


For the C4 Picasso from the equipment line Intense a so-called active cruise control is available as an option, which operates at speed differences in the range of 25 km / h and using radar maintains a preselected distance.


Since June 2006 can also be ordered for the Ford S -MAX and Galaxy to an adaptive cruise control. For the Mondeo which is possible since June 2007 and for the Focus since April 2011. Active ACC is between 30 and 180 km / h and includes the Collision Forward Alert (FA ) is a function that warns by audible and visual indication of an impending rear-end collision. FA biases in case of a detection before the brake and thus increases the braking force / shortens the braking distance. The distance can be ( close to far ) selected in five steps by the driver.


Since autumn 2006, the Honda Legend, the Honda Accord as well as the new Honda CR-V available from model year 2007 with adaptive cruise control.

Jaguar and Land Rover

Jaguar offers the adaptive cruise control system in the XF, XJ and XK models. A Jaguar XKR was also, according to Jaguar site the first car ever to hit the market with such a device. Land Rover Range Rover Sport offers the adaptive cruise control.


In North America, Lexus offered already since 2000 in the LS a laser-based adaptive cruise control system. Since August 2004, the LS model is available in Europe with a radar - based adaptive cruise control system that works together with the PCS - safety system ( Pre Crash Safety System). Since 2006, the system is also available for the Lexus IS models, RX and GS.

Maybach and Mercedes -Benz

In 1998, Mercedes -Benz under the name Distronic in the S-Class ( 220 series ) a proximity control system on the market, which was available from 1999 in the new CL-Class ( C 215 ). The Distronic regulates the range of 30 to 160 km / h the distance ( either low to high ) to the vehicle ahead. Should heavy braking be necessary, the driver is warned optically and acoustically. Since the facelift of the Series 220 and the C 215 got a radar with an active range from 30 to 180 km / h are used. The Distronic is offered as an option in the current series of the CLK, CLS, ML, GL-, E-, R- and SL -Class and the Maybach 57 and 62 to this day.

2001 Mercedes -Benz realized also under the name Telligent claims to be the first adaptive cruise control for heavy duty vehicles, which not only throttles the engine to adjust the safety distance, but also controls the brake system.

Came in 2005 in the new S -Class (W / V 221) Distronic Plus on the market. An additional millimeter wave radar for short range measurement reliability and functionality. The Distronic Plus is active and thus be used as a Traffic Jam Assistant in the range from 0 to 200 km / h. At the same time the short-range radar is used as a parking aid with no visible sensors and works without ultrasound. In an emergency situation the driver visual and audible warnings and - if he responds - BAS Plus ( radar- controlled Brake Assist ) supports up to a stop at the optimum braking force. In this so-called target braking only as much as necessary braking force is applied to prevent an accident. Thus extended for the subsequent transport of the available stopping distance to avoid rear-end collisions. BAS Plus can always be overridden by the driver.

The new adaptive cruise control made ​​in November 2005 in a test of car picture in collaboration with DaimlerChrysler for attention. In this test, the new adaptive cruise control system of the S-Class should be demonstrated. The driving situation in the fog could only be simulated in a hall. In this system, however, works both because of the steel structure of the hall, and because of the many electronic systems at that not always. As employees of DaimlerChrysler knew this in advance, a board was placed on the hall floor, from which also inaugurated into the problem and used for this experiment as a driver car image editor Michael Specht should slow down. The first attempt failed and the steered by Specht vehicle drove on the last vehicle of the simulated traffic jam end in the artificial fog. In another, equally bogus tests succeeded woodpecker, to bring the vehicle to a stop in time.

Because the camera crew through microphones that previously registered the lack of warning in the vehicle interior, could hear the internal conversations between woodpecker and the employees of Daimler Chrysler, flew to the dizziness. DaimlerChrysler apologized for the incident and offered a re-test. The experiment was repeated with neutral drivers under normal outdoor conditions, the system worked perfectly in 16 attempts.

2009, the performance of the PRE -SAFE brake has been enhanced in the new E -Class (W / S 212), the vehicle will react first case of imminent Auffahrunfallgefahr with a visual and audible warning, then a partial braking. Should not react, the driver and the accident are recognized as unavoidable, a temporary autonomous emergency braking is required. Thus, the severity of the crash again be significantly reduced. The system can be overridden at any time by the driver.

2011 is the DistronicPlus arrived in the new B-Class and 2012 in the new A- class and governs here even to a stop.


In 1998, Nissan an adaptive cruise control system based on radar at Cima in the Japanese market. From 2000, other platforms came with adaptive cruise control based on infrared on the European and North American market.

As of mid-2002 there was the Abstandsregeltempomaten the Primera as an option, but only in the version " Tekna " with the 2- liter engine (103 kW/140 hp) and the 6-speed CVT automatic transmission with Tiptronic. He was at one time the only midsize car in Germany, which could be equipped with this technology.

Since 2005, Nissan offers the expansion of the congested traffic. With over 17 platforms, the Nissan - ACC system is by far the best-selling worldwide.


The " adaptive cruise control with automatic emergency braking " led Opel Zafira Tourer 2011 a, the models Astra, Insignia and the Insignia Sports Tourer with this assistance system available in 2012.


In 2006 Volvo offered in the flagship S80 an autonomous cruise control system as an optional extra. In 2007, the model series V70 and XC70 added. The system performs the well-known distance control and also has the Brake Assist Pro. This prepares Brake Assist in emergency situations before the brake system on an emergency braking, also the driver is acoustically pointed via a head -up display visually and by warning tones on the risk situation.

For 2008, a functional expansion was planned, which includes an automatic partial braking function with 50 % of the maximum braking force. Here, a camera is used in addition to the radar system, which reliably detects stationary obstacles like animals, traffic congestion, etc.. If the measured values ​​of camera and radar system match, the driver is warned. The driver fails to respond yet, in active follow- ride the above Partial braking run - but only after a collision with the obstacle can just be avoided. This is a compromise of high conservation at the same time the longest possible preservation of the driver's freedom of action.