Adaptive cruise control

Adaptive cruise control (ACC) is an advanced driver-assistance feature that supplements, but does not replace, the role of the driver. The system automates longitudinal vehicle control by adjusting throttle and, in many systems, applying braking to maintain a preset following distance, but it requires continuous driver supervision and does not replace the driver's responsibility for vehicle operation. During operation, the driver selects a desired cruising speed and following distance. If the vehicle approaches slower-moving traffic, ACC automatically reduces engine power and may apply braking to maintain the selected gap. When traffic conditions permit, the vehicle accelerates back to the preset speed. Some full speed range systems are capable of functioning in stop-and-go traffic, though driver attention remains required. Pricing Adaptive cruise control is commonly offered as standard equipment on higher trim levels, or as part of optional safety or technology packages. The inclusion of ACC may increase a vehicle's price by several hundred to several thousand U.S. dollars depending on the manufacturer and the features bundled with the system. Because ACC is frequently packaged with other ADAS technologies, such as lane-keeping assist or automatic emergency braking, buyers may pay for a broader safety suite rather than the feature as a standalone option. == Types ==

ACC systems are commonly distinguished by the sensing technologies used to detect and track vehicles ahead, most often radar, lidar, cameras, or combinations of these sensors. or the 2010 Volkswagen Touareg, or one central long range radar coupled with two short radar sensors placed on the corners of the vehicle like the BMW 5 and 6 series. Lidar-based systems Laser-based systems work using LIDAR (Light detection and ranging), allowing laser-based ACC to provide the largest detection distance as well as the best accuracy of all ACC systems. Laser based ACC systems also have a more difficult time tracking dirty (and therefore non-reflective) vehicles. Laser-based sensors must be exposed, the sensor (a fairly large black box) is typically found in the lower grille, offset to one side. Camera-based systems Camera-based adaptive cruise control (ACC) uses one or more forward-facing cameras to detect and track vehicles ahead using computer vision. Instead of directly measuring range with reflected radio waves (radar) or laser pulses (lidar), camera-based systems infer distance and closing speed from image cues such as object size and motion across frames, and when stereo cameras are used, by estimating depth from parallax between two views. Some camera-based ACC implementations use stereo (binocular) camera arrangements mounted near the windshield, enabling depth perception without radar. Subaru's EyeSight is a well-known example of this approach; Subaru describes EyeSight as using camera-based sensing to support adaptive cruise control and related driver-assistance functions. Multi-sensor systems Some ACC systems combine multiple sensor types, most commonly radar and cameras, to improve vehicle detection and tracking across varying conditions. In such systems, radar provides robust range and relative-speed measurements, while cameras provide additional visual context for object classification and scene interpretation. == Predictive systems ==

Predictive adaptive cruise control (PACC) builds on conventional ACC by incorporating forward-looking data and behavioral estimation to modify vehicle speed in anticipation of upcoming conditions. Rather than reacting only to the distance and relative speed of a preceding vehicle, predictive systems use additional information to adjust speed proactively. In production vehicles, PACC uses navigation and map data to anticipate roadway features. Some systems incorporate GPS location data, digital maps, and traffic sign recognition to automatically adjust vehicle speed in response to upcoming curves, changes in speed limits, or highway exits. By combining sensor input with navigation information, the system can reduce speed before reaching a lower speed zone or approaching a bend, rather than responding after the change occurs. Guidance from U.S. and insurance-industry safety organizations emphasize that these systems remain assistance features and still require active driver supervision. ==Regulations==

Adaptive cruise control (ACC) is regulated primarily by ISO 15622:2018 — Intelligent transport systems — Adaptive cruise control systems — Performance requirements and test procedures, which establishes minimum functional requirements, control behavior, driver interface elements, diagnostics, and performance test procedures for ACC systems. The standard defines ACC as a partial automation of longitudinal vehicle control and distinguishes between Full Speed Range Adaptive Cruise Control (FSRA) and Limited Speed Range Adaptive Cruise Control (LSRA) systems. Because ACC systems may automatically apply braking, they must also comply with applicable vehicle braking regulations. In countries applying the UNECE framework, braking performance and electronic braking control requirements are governed by UN Regulation No. 13-H, which sets safety and performance standards for passenger car braking systems. ACC systems that provide active brake control must operate within the limits prescribed by these braking regulations. == History ==

Adaptive cruise control developed during the 1990s as an extension of conventional cruise control, initially focusing on forward distance detection rather than full longitudinal automation. • 1995: Mitsubishi Diamante introduced laser "Preview Distance Control". This system controlled speed through throttle control and downshifting, but could not apply the brakes. • 1997: Toyota offered a "laser adaptive cruise control" (lidar) system on the Japanese market Celsior. It controlled speed through throttle control and downshifting, but could not apply the brakes. • 1999: Mercedes introduced "Distronic", the first radar-assisted ACC, on the Mercedes-Benz S-Class (W220) and the CL-Class. • 1999: Jaguar began offering a radar-based ACC system on the Jaguar XK (X100). • 1999: Nissan introduced laser ACC on the Japanese market Nissan Cima. • 1999: Subaru introduced world's first camera-based ACC on the Japanese-market Subaru Legacy Lancaster. • 2000: BMW introduced radar "Active Cruise Control" in Europe on the BMW 7 Series - E38. • 2000: Toyota was the first to bring laser ACC to the US market in late 2000, with the LS 430 Dynamic Laser Cruise Control system. • 2000: Toyota's laser ACC system added "brake control", that also applies brakes. (supplied by Bosch) • 2002: Lancia introduced radar ACC (by Bosch) on the Lancia Thesis • 2002: Volkswagen introduced radar ACC, manufactured by Autocruise (now TRW), on the Volkswagen Phaeton. • 2002: Audi introduced radar ACC (Autocruise) on the Audi A8 in late 2002 • 2003: Cadillac introduced radar ACC on the Cadillac XLR. • 2003: Toyota shifted from laser to radar ACC on the Celsior. • 2004: Toyota added "low-speed tracking mode" to the radar ACC on the Crown Majesta. • 2005: In the United States, Acura introduced radar ACC integrated with a Collision avoidance system (Collision Mitigation Braking System (CMBS)) in the model year 2006 Acura RL. • 2005: Mercedes-Benz S-Class (W221) upgraded ACC to completely halt the car if necessary (now called "Distronic Plus" on E-Class and most Mercedes sedans). • 2006: Volkswagen Passat B6 introduced radar ACC supplied by Autocruise and TRW, functioning from . It supported additional functions AWV1 and AWV2 to prevent collisions by using the brake system. • 2006: Audi introduced full speed range ACC plus on the Audi Q7. In low-speed mode, it warns the driver of a potential collision and prepares emergency braking as needed. The system was supplied by Bosch. • 2006: Nissan introduced "Intelligent Cruise Control with Distance Control Assist" on Nissan Fuga. It pushes the gas pedal against the foot when the navigation system observes an unsafe speed. If the Autonomous cruise control system is used, the Distance Control Assistance reduced speed automatically and warned the driver with an audible bell sound. • 2006: September 2006 Toyota introduced its "all-speed tracking function" for the Lexus LS 460. • 2007: BMW introduced full-speed Active Cruise Control Stop-and-Go on the BMW 5 Series (E60). • 2008: Lincoln introduced radar ACC on the 2009 Lincoln MKS. • 2008: SsangYong Motor Company introduced radar "Active Cruise Control" on the SsangYong Chairman • 2008: Volkswagen Passat CC, B6 and Touareg GP. The ACC system was updated to support a full auto stop and added Front Assist function to prevent collisions working separately of ACC. Front Assist cannot brake automatically, it only increases the pressure in the brake system and warns the driver. • 2008: Volkswagen Golf 6 introduced ACC with lidar. • 2009: Hyundai introduced radar ACC on Hyundai Equus in Korean market. • 2009: ACC and CMBS also became available as optional feature for the 2010 Acura MDX Mid Model Change (MMC) and the newly introduced model year 2010 Acura ZDX. • 2010: Ford debuted its first ACC on the sixth generation Ford Taurus (option on most models, standard on the SHO) • 2010: Audi introduced a GPS-guided radar ACC on Audi A8#D4 • 2010: Volkswagen Passat B7, CC. Update of ACC and updated Front Assist. Introduced emergency braking, named "City". The car could brake automatically to prevent a collision. • 2010: Jeep introduced ACC on the 2011 Jeep Grand Cherokee • 2012: Volkswagen made ACC standard on the Volkswagen Golf MK7 SE and above. • 2013: Mercedes introduced "Distronic Plus with Steering Assist" (traffic jam assist) on the Mercedes-Benz S-Class (W222) • 2013: BMW introduced Active Cruise Control with Traffic Jam Assistant. • 2014: Chrysler introduced full speed range radar "Adaptive Cruise Control with Stop+" on the 2015 Chrysler 200. • 2014: Tesla Motors introduced autopilot feature to Model S cars, enabling semi-autonomous cruise control. • 2015: Ford introduced the first pickup truck with ACC on the 2015 Ford F150. • 2015: Honda introduced its European CR-V 2015 with predictive cruise control. • 2015: Volvo began offering ACC on all its models. • 2017: Cadillac introduced its Super Cruise semi-autonomous feature in the model year 2018 CT6 (for cars produced on or after 6 September 2017). The system used onboard radar and cameras along with lidar mapping data, allowing the driver to go hands-free on limited-access highways. • 2017: Toyota introduced its safety sense on all models as a standard feature. Toyota Safety Sense P (TSS-P) includes DRCC (dynamic radar cruise control) that uses a front-grille-mounted radar and a forward-facing camera that is designed to detect a vehicle in front and automatically adjust the vehicle's speed to help maintain a pre-set distance behind a vehicle ahead. == Vehicle models supporting adaptive cruise control ==

The three main categories of ACC are: • Vehicles with Full Speed Range 0MPH are able to bring the car to a full stop to and need to be re-activated to continue moving with something like a tap of the gas pedal. • Vehicles with Traffic Jam Assist / Stop & Go auto-resume from standstill to creep with stop and go traffic. • Vehicles with Partial cruise control cuts off and turns off below a set minimum speed, requiring driver intervention. • Vehicles with fully automated speed control can respond to traffic signals and non-vehicular on-road activity. Mercedes Distronic Plus 4MATIC Coupe. The forward-facing Distronic sensors are usually placed behind the Mercedes-Benz logo and front grille. In 1999, Mercedes introduced Distronic, the first radar-assisted adaptive system, on the Mercedes-Benz S-Class (W220) and the CL-Class. In 2016, Mercedes introduced Active Brake Assist 4, the first emergency braking assistant with pedestrian recognition. One crash caused by Distronic Plus dates to 2005, when the German news magazine Stern was testing Mercedes' original Distronic system. During the test, the system did not always manage to brake in time. Ulrich Mellinghoff, then Head of Safety, NVH, and Testing at the Mercedes-Benz Technology Centre, stated that some tests failed because the vehicle was tested in a metallic hall, which caused problems with radar. Later iterations received an upgraded radar and other sensors, which are not disrupted by a metallic environment. In 2008, Mercedes conducted a study comparing the crash rates of Distronic Plus vehicles and vehicles without it, and concluded that those equipped with Distronic Plus have an around 20% lower crash rate. == Aftermarket ==

For some models of cars, Comma.ai offers an aftermarket alternative to factory-built ACC systems through its openpilot software paired with Comma hardware. When installed in a compatible vehicle, OpenPilot replaces or adds to existing ADAS features. This effectively brings Level-2 capabilities to some cars that originally did not have them. == See also ==