Adaptive cruise control

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The red car follows the blue car semi-automatically with ACC

An adaptive cruise control is a cruise control system in motor vehicles , which in the scheme involving the distance to a preceding vehicle as an additional return and control variable. Adaptive cruise control is one of the driver assistance systems .

The English term Adaptive Cruise Control ( ACC ) has established itself in the international automotive industry (in German: Adaptive Cruise Control ).

The system is also referred to as automatic distance control ( ADR ), although other names can be used because automobile manufacturers like to name their systems individually in order to better differentiate themselves.

The system is often part of a radar-based emergency brake assistant and, in some cars, has a stop-and-go function.


ACC sensor
ACC radar antenna

With adaptive cruise control, the position and speed of the vehicle in front is determined with a sensor and the speed and the distance of the following vehicle equipped with this system are controlled adaptively with engine and brake intervention (longitudinal control).

Adaptive cruise control systems are mostly used in vehicles with automatic transmissions , since gear changes are carried out automatically by the transmission. In the case of manual gearshifts, a flashing display prompts the driver to change gear.

The primary goal is to increase comfort and relieve the driver's concentration on long motorway journeys, but also in less fluid city traffic. Secondly, the gain in security is pursued:

  • Simple systems enable an optical and acoustic warning function for the driver as well as a max. Delay in braking intervention of up to 25% of the max. possible delay. The value is limited in order to minimize the effects of incorrect detections (according to ISO 15622 - but no legal requirement).
  • Advanced systems also prepare the braking system for any subsequent emergency braking with the aim of shortening the stopping distance.
  • Current systems can perform autonomous emergency braking to a standstill (for example in stop-and-go traffic ). In addition to radar signals, some of them also use camera images for close range. A future step will be the automatic avoidance and avoidance of obstacles.

Some manufacturers now also offer a “ follow-to-stop ” function that follows a vehicle in front until it comes to a standstill. In contrast to the stop-and-go system, the vehicle does not start off again automatically with a follow-to-stop. With the stop-and-go function, it is possible to start off independently after a short standstill or to start off again with driver triggering (after driver confirmation by tapping the accelerator pedal or actuating the control lever) up to the speed specified by the driver. This function is used to increase the driver's comfort in cities and in traffic jams on the motorway.

Radar sensors are mainly used for distance measurement in today's vehicles, but lidar systems are not yet widely used.


The radar systems work with a power of approx. 10 mW. This performance is so low that no health effects are to be expected. The radar frequency permitted for this application is mostly in the 76–77  GHz range , corresponding to a wavelength of around 4 mm (see millimeter wave ). Older developments use the frequency range of 24 GHz. These systems can be manufactured more cheaply, but the use of this frequency spectrum is limited in time. In addition, the larger wavelength at 24 GHz results in larger antenna structures, which are avoided. The latest systems use a spectrum in the 77–81 GHz range.


The lidar systems do not work with visible light, but with radiation in the infrared range . They have a comparably low output that is safe for the eyes ( laser class 1M). The technology has the:

  • Disadvantage of the high level of interference in weather conditions restricting visibility and a significantly shorter range than radar,
  • Advantage of the significantly lower part price and sharper image with better resolution than radar sensors.

Driving safety

Impairments to the ability to drive and the driver's attention have not been proven, but risk compensation is always feared. By relieving the strain on routine tasks (constant checking of the speedometer , accelerating and braking), the driver may be less tired and can then concentrate better on what is happening on the road. Likewise, when visibility is poor, some drivers are tempted to drive far faster than appropriate, as it is assumed that the system will continue to work properly. This is why some manufacturers switch off the systems when visibility is limited.


Adaptive cruise control combined with car-to-car communication enables platooning . Several vehicles drive one behind the other at a very short distance and can thus save fuel, comparable to driving in the slipstream during cycling races. The reduced response time to 0.2 to 0.3 seconds increases security. The legal framework for this is still lacking in Germany.

Adaptive cruise control from various manufacturers

Audi, Bentley, Seat, Škoda and VW

Distance graphic

Since 2002, Audi and VW have been offering adaptive cruise control in their luxury-class models A8 and Phaeton . Since then, various revised versions have been launched:

  • First generation ACC (active from 30 to 180 km / h): from 2002 in the A8 and Phaeton
  • Second generation (active from 30 to 200 km / h): from 2004 in the Audi A6 C6
  • Third generation (active from 30 to 210 km / h and, if necessary, preparation of the brake system for emergency braking): from 2005 in the VW Passat B6
  • Fourth generation (active from 0 to 200 km / h): Warning through " environment monitoring " of a dangerous situation through several short, autonomous brake jolts: from 2006 in the Audi Q7 and VW Touareg and since 2007 also in the VW Phaeton, in the Audi A4 B8 (control range in the A4 B8 and in the A5 only from 30 to 200 km / h) and in the VW Passat CC .
  • The fourth generation system was taken over from the VW Phaeton and has also been offered as an option in the Bentley Continental models GT , 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 two radar sensors, a video camera and the sensors of the parking aid. In slow-moving traffic or in a traffic jam, it regulates braking and starting. The system extends the fourth generation warning function. In conjunction with the radar sensors of the lane change assistant , autonomous full deceleration is initiated in situations in which a collision is unavoidable in order to reduce the severity of the impact as much as possible.
  • For the VW Golf VII , ACC with Stop & Go function and an integrated city ​​emergency braking function as well as Front Assist is optionally available.
  • A traffic jam assistant is introduced with the VW Passat B8 . The vehicle can drive partially autonomously behind a vehicle at up to 60 km / h. The accelerator and brake functions as well as the steering are taken over. The driver only needs to have his hands on the steering wheel. The system is a fusion of the lane departure warning system and the ACC sensor.
  • The ACC has been available in the Škoda Octavia III and Seat Leon III since 2013, and in the Škoda Fabia III from model year 2017.
  • The ACC system is installed in the Audi A3 from model year 2013.


BMW calls the ACC system Active Cruise Control . Not to be confused with the in-house Adaptive Drive , an active stabilizer system.

The first generation was introduced in April 2000 in the 7 series ( E38 ). Three radar lobes measure a driving angle of 8 ° over a distance of max. 150 m from. Radar lobes and evaluation electronics including longitudinal control are integrated in the ACC sensor. The second generation was introduced with the 6 series ( E63 / E64 ) in 2004. A further developed radar sensor now measures a driving angle of 16 ° with four radar lobes. Information from the navigation system about the type and course of the road is also incorporated. As a result, the ACC control behaves in a more anticipatory and thus more comfortable manner.

In March 2007, the active cruise control in the 5-series ( E60 / E61 ) was supplemented by the stop & go function. The system is active from 0–180 km / h; in traffic jams it can automatically follow the traffic and, if necessary, brake to a standstill. The vehicle starts moving again automatically within three seconds of stopping or afterwards via driver confirmation. BMW uses the iBrake safety function for this. In dangerous situations, the activation thresholds of the brake assistant are lowered depending on the situation, the brake circuits are pre-filled and the brake pads are imperceptibly applied to the brake discs, thus preparing the brake system for any subsequent emergency braking by the driver. The maximum possible deceleration during braking is 40% of the maximum braking force.

The last expansion stage ( autonomous emergency braking with maximum braking force) has been available since the facelift of the BMW 7 Series in 2012. This combines the sensor functions of the camera in the mirror base and the ACC sensor. This makes the distance control more sensitive and corresponds more closely to the human driving style.


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


Since summer 2007, Chrysler has offered a lidar-based ACC system from Hella for the 300C on the list of extras. However, this is only available for the SRT8-6.1 engine.


For the C4 Picasso from the Intensive equipment line, Citroën optionally offers a so-called active cruise control, which works in the case of speed differences in the range of 25 km / h and maintains a preselected distance by means of radar.


Adaptive cruise control has been available as an option for the Ford S-MAX and Galaxy since June 2006 . The system has been available for the Mondeo since June 2007 and for the Focus since April 2011 . ACC between 30 and 200 km / h active and contains the Forward Collision Warning Forward Alert (FA) is a function that alerts via audible and visual indicator of an impending rear-end collision. In the event of detection, FA preloads the brake, thus increasing the braking force and thereby shortening the braking distance. The distance can be selected by the driver in five steps (close to far). Since the year of construction 2018 in the S-MAX with Stop & Go from 0 - 200 km / h. Braking up to 0 km / h. The vehicle in front is followed automatically for up to 3 seconds. Then either the accelerator pedal has to be pressed briefly or the continuation of the journey has to be allowed via the res button, similar to BMW.


In 2003, the Honda Inspire introduced the radar-based Intelligent Highway Cruise Control (IHCC). The Honda Legend , the Honda Accord and, from year of construction 2007, the new Honda CR-V with adaptive cruise control have been available since autumn 2006 .

Jaguar and Land Rover

Jaguar will be offering adaptive cruise control in the XF, XJ and XK models from 1999. A Jaguar XKR was also the first car ever to come onto the market with such a facility, according to the Jaguar website.

The Land Rover brand offers adaptive cruise control in the Range Rover Sport .


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


Mazda has been offering a radar-based proximity control system since 2012 under the name MRCC "Mazda Radar Cruise Control". This was initially only available for the Mazda 6. The system works in the speed range from 30 to 200 km / h and detects vehicles up to 140 meters away. This system can now also be configured for the Mazda 3, CX5 and CX3 and is sold with other additional electronic driver assistance systems under the name i-Activesense.

Maybach and Mercedes-Benz

As early as 1999, Mercedes-Benz launched an adaptive cruise control in the S-Class (220 series) under the name Distronic , which was also available in the new CL-Class (C 215) from 1999 . The Distronic regulates the distance (optionally small to large) to the vehicle in front in the range of 30 to 160 km / h. If heavy braking is necessary, the driver is warned visually and acoustically. Since the model update of the 220 and C 215 series, a radar with an active range of 30 to 180 km / h has been used. The Distronic is still offered as an option in the current model series of the CLK, CLS, ML, GL, E, R and SL-Class as well as in the Maybach 57 and 62 .

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

In 2005 the Distronic Plus came onto the market in the new S-Class (W / V 221) . An additional millimeter wave radar for close range increases the measurement reliability and the range of functions. The Distronic Plus is active in the range from 0 to 200 km / h. At the same time, the short-range radar is used as a parking aid without visible sensors and works without ultrasound. In a dangerous situation, the driver is warned visually and acoustically and - if he reacts - supported by BAS Plus (radar-controlled brake assistant) with the optimal braking force until the vehicle comes to a standstill. With this so-called target braking, only as much braking force as necessary is applied to prevent an accident. The stopping distance available for the following traffic is thus extended in order to avoid rear-end collisions. BAS Plus can be overridden by the driver at any time.

The new adaptive cruise control caused a sensation in November 2005 during a test by Auto Bild in cooperation with DaimlerChrysler . The aim of this test was to demonstrate the new distance control system in the S-Class. The driving situation in the fog could only be simulated in a hall. In this, however, the system did not always work due to the steel structure of the hall and the many electronic systems in the same. As the DaimlerChrysler employees knew this in advance, a board was placed on the hall floor from which the Auto-Bild editor Michael Specht, who was also introduced to the problem and who was the driver for this experiment, was supposed to brake. The first attempt failed and the vehicle driven by Specht hit the last vehicle of the simulated end of the traffic jam in the artificial fog. In further tests, simulated in the same way, Specht succeeded in bringing the vehicle to a standstill in good time.

Since the camera team was able to overhear the internal conversations between Specht and the DaimlerChrysler employees through microphones that had previously registered the missing warning tone in the vehicle interior, the dizziness was discovered. DaimlerChrysler apologized for the incident and offered to retest. The test was repeated with neutral drivers under normal outdoor conditions, with the system functioning flawlessly in 16 tests.

In 2009, the performance of the PRE-SAFE brake was expanded: in the E-Class (W / S 212 series) , if there is a risk of a rear-end collision, the vehicle initially reacts with an optical and acoustic warning, then with partial braking. If the driver does not react and the accident is recognized as unavoidable, a time-limited autonomous emergency braking is requested. This can significantly reduce the severity of the impact. The driver can override the system at any time.

In 2011 the Distronic Plus was integrated in the new B-Class and in March 2011 in the model maintenance of the C-Class. In 2012 it arrived in the new A-Class and even regulates here until it comes to a complete stop.


1992 Mitsubishi the first manufacturer in Mitsubishi Debonair a lidar -based distance measurement system introduced. It was called Distance Warning and could only warn the driver, but not influence the throttle valve, brakes or gearshift. In 1995 the Mitsubishi Diamante introduced the laser-assisted Preview Distance Control . It could operate the throttle and shift, but not brake. With the introduction of the new Outlander in 2012, adaptive cruise control, called ACC at Mitsubishi, was offered for the first time. It is offered in the Mitsubishi Outlander and Mitsubishi Plug-In Hybrid Outlander . It is combined with a collision warning system that actively brakes if the distance is too short. At speeds below 30 km / h, the car brakes to a standstill.


In 1998 Nissan brought a lidar- based adaptive cruise control to the Nissan Cima . From 2000 onwards, additional platforms with adaptive cruise control based on infrared came onto the European and North American markets.

From mid-2002, adaptive cruise control was available as an option on the Primera , but only on the "Tekna" version with the 2-liter engine (103 kW / 140 PS) and the 6-speed CVT automatic with Tiptronic. At the time, it was the only mid-range car in Germany that could be equipped with this technology.

Since 2005 Nissan has been offering the extension to the traffic jam assistant. With over 17 platforms worldwide, the Nissan ACC system is by far the best-selling.


Opel introduced the adaptive cruise control with automatic emergency braking in 2011 in the Zafira Tourer, and in 2012 the Astra , Insignia and Insignia Sports Tourer models will also be available with this assistance system.


In 1997 Toyota introduced the Laser Adaptive Cruise Control ( lidar ) system in the Toyota Celsior . It could reduce speed through throttle and shift, but not apply the brakes. Brake actuation was introduced in 2000. In 2003, the lidar-sensor has been through a millimeter wave - Radar replaced. This system has been available in Germany since 2009 and has been continuously improved. The current series Prius, Avensis, RAV4 and C-HR are now available with distance radar; In some cases, this equipment feature can even be found in the respective base model. The system built into the Prius 4 can, in conjunction with the PreCrash Assistant, brake the vehicle to a standstill or support the driver in the event of an emergency stop.


In 2006, Volvo offered adaptive cruise control as an option in the top model S80 . In 2007 the V70 and XC70 model series were added. The system carries out the familiar distance control and also has Brake Assist Pro. In an emergency, this brake assistant prepares the brake system for emergency braking; the driver is also informed of the dangerous situation visually via a head-up display and acoustically through warning tones.

An expansion of functions was planned for 2008, which includes an automatic partial braking function with 50% of the maximum braking force. In addition to the radar system, a camera is used which also reliably detects standing obstacles such as animals, the end of a traffic jam, etc. If the measured values ​​from the camera and radar systems match, the driver is warned. If the driver still does not react, the above mentioned will be activated if the following journey is active. Partial braking performed - but only when a collision with the obstacle can just about be avoided. This is a compromise between high protection and at the same time preserving the driver's freedom of action for as long as possible.


Individual evidence

  1. Daimler Trucks is testing truck platooning on public highways in the USA. Retrieved October 24, 2019 .
  3. Fabia model year 2017. In: skodaportal. Retrieved October 31, 2016 .
  4. Audi A3 and ACC .
  5. ^ Honda Intelligent Driver Support (HiDS) . Honda. October 22, 2003. Archived from the original on May 9, 2009. Retrieved January 19, 2015.
  6. ( Memento from September 8, 2008 in the Internet Archive )
  7.  ( page no longer available , search in web archives )@1@ 2Template: Toter Link /
  8.  ( page no longer available , search in web archives )@1@ 2Template: Toter Link /
  9. Mazda Radar Cruise Control ( Memento from March 22, 2016 in the Internet Archive )
  10. i-Activesense driver assistance system ( Memento from March 22, 2016 in the Internet Archive )
  11. Innovative by tradition . Daimler AG. November 27, 2014. Archived from the original on January 18, 2015. Retrieved January 19, 2015.
  13. Vehicle technologies to improve performance and safety ( Memento of October 11, 2003 in the Internet Archive )
  14. - ( Memento from December 30, 2014 in the Internet Archive ) History of Mitsubishi Motors.
  15. costs. In: Focus Online . January 25, 2002, accessed October 14, 2018 .
  16. Electronics Parts . Toyota. 2012. Retrieved January 18, 2015.