Collision avoidance system

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This article is about collision avoidance in automobiles; for other modes, see collision avoidance (disambiguation).

A collision avoidance system is an automobile safety system designed to reduce the severity of an accident. Also known as precrash system, forward collision warning system or collision mitigating system, it uses radar (all-weather) and sometimes laser and camera (both sensor types are ineffective during bad weather) to detect an imminent crash. Once the detection is done, these systems either provide a warning to the driver when there is an imminent collision or take action autonomously without any driver input (by braking or steering or both). Cars with Collision avoidance are also equipped with adaptive cruise control, and use the same sensors like ACC.


In 2009, the U.S. National Highway Traffic Safety Administration (NHTSA) began studying whether to make frontal collision warning systems and lane departure warning systems mandatory.[1]

In 2011, a question was submitted to the European Commission regarding stimulation of these "collision mitigation by braking" systems.[2] The mandatory fitting of Advanced Emergency Braking Systems in commercial vehicles will be implemented on 1 November 2013 for new vehicle types and on 1 November 2015 for all new vehicles in the European Union.[3] This could, according to the impact assessment,[4] ultimately prevent around 5,000 fatalities and 50,000 serious injuries per year across the EU.

A 2012 study[5] by the Insurance Institute for Highway Safety examined how particular features of crash-avoidance systems affected the number of claims under various forms of insurance coverage. The findings indicate that two crash-avoidance features provide the biggest benefits: (a) autonomous braking that would brake on its own, if the driver does not, to avoid a forward collision, and (b) adaptive headlights that would shift the headlights in the direction the driver steers. They found lane departure systems to be not helpful, and perhaps harmful, at the circa 2012 stage of development.

Collision avoidance features are rapidly making their way into the new vehicle fleet.

Automobile manufacturers[edit]


2006: "Braking guard" radar-assisted forward collision warning introduced on Audi Q7.

2010: "Pre sense" autonomous emergency braking system uses twin radar and monocular camera sensors[6] and was first introduced in 2010 on the 2011 Audi A8.[7] "Pre Sense Plus" works in four phases. In the first phase, the system provides warning of an impending accident, while the hazard warning lights are activated, the side windows and sunroof are closed and the front seat belts are tensioned. In the second phase, the warning is followed by light braking, strong enough to win the driver's attention. The third phase initiates autonomous partial braking at a rate of 3 m/s² (9.8 ft/s²). The fourth phase decelerates the car at 5 m/s² (16.4 ft/s²) followed by automatic deceleration at full braking power, roughly half a second before projected impact. "Pre Sense Rear", is designed to reduce the consequences of rear-end collisions. The sunroof and windows are closed and seat belts are prepared for impact. The optional memory seats are moved forward to protect the car's occupants.

2015 introduced the "Avoidance Assistant": intervenes in the steering to help the driver avoid an obstacle. If an accident occurs. The "Turning Assistant" monitors opposing traffic when turning left at low speeds. In critical situation, it brakes the car. "Multicollision brake assist" uses controlled braking maneuvers during the accident to aid the driver. Both systems introduced in 2015 on the Second generation Q7.[8]


In 2012 BMW introduced "Active Protection System" + "Active Driving Assistant" on the facelifted BMW 7 Series (F01)#2012 update.

2013 "Driving Assistant Plus": A combination of front camera and full-range radar sensors detects all vehicles ahead, whether moving or stationary. Should the driver not react to the warning of a potential collision, the Driving Assistant Plus automatically slows the vehicle down – with maximum deceleration power if necessary.

Active Protection detects imminent accidents, then prepares by automatically pretensioning safety belts, closing windows and moonroof, backrest of the front passenger seat brought into an upright position, and activating post-crash braking. Also includes driver drowsiness detection that analyses driving behaviour and, if necessary, advises the driver to rest. The advice to take a break is provided in the form of graphic symbols shown on the Control Display.

Active Driving Assistant includes lane departure warning, pedestrian protection, and city collision mitigation.

Driving Assistant comprises the Lane Departure Warning as well as "Approach and Pedestrian Warning with City Brake Activation". The system detects vehicles driving ahead and, at speeds of up to 60 km/h, also persons who are on a possible collision course. In an identified hazard situation, the driver is warned by means of visual and acoustic signals. In order to shorten the stopping distance, the braking system is simultaneously preconditioned. Furthermore, at speeds of up to 60 km/h an emergency braking manoeuvre with medium deceleration is also activated in order to reduce speed and draw the driver’s attention to the critical situation.

"Lane Change Warning assistant", also available as an individual option, can be used from a speed of 20 km/h. The system monitors the traffic situation on the adjacent lane in the area called the dead spot and warns he driver of potential critical situations during overtaking manoeuvres.

After an accident, automatic braking can bring the vehicle to a standstill, thus preventing or reducing the likelihood of follow-on collisions.


In 2012 Cadillac introduced two systems on the Cadillac XTS, now also available on ATS, CTS and Escalade: Forward Collision Alert which uses a camera to detect and warn you when an impact may be imminent. Front and Rear Automatic Braking detects when a frontal or rear collision is imminent and automatically applies the brakes to lessen impact severity, helping the driver avoid certain low speed impacts all together. Featured automatic braking at low speeds (in heavy traffic or even in parking lots and driveways) when a collision is imminent [9]


2010: The 2011 Jeep Grand Cherokee with Forward Collision Warning[10]

2014: Chrysler 200 and 300 introduced Full-Speed Forward Collision Warning (FCW) with Active Braking. System readies the brakes and alerts the driver when it senses a potential frontal impact. If the driver doesn’t respond and the risk of a collision continues, the brakes can bring the vehicle to a full stop. Advanced Brake Assist will increase the brake force automatically if the force applied is not sufficient.


Fiat's autonomous emergency braking system, dubbed City Brake Control, is an urban low-speed crash avoidance system that works between 5 and 30 km/h. It was first made available as an option on the third generation Panda; it was consequently introduced on the 500L and its variants, again as an option. The system employs a laser Lidar sensor located on top of the windscreen, that communicates with the ESP. If an impending collision is detected it intervenes in three steps: at first with brake pre-fill, for quicker response at the driver's reaction; secondly enhancing the hydraulic brake assist sensitivity; finally, if the driver still has not reacted, it automatically applies the brakes and simultaneously warns the occupants through a buzzer.[11]

In 2013 City Brake Control was tested and deemed effective by Euro NCAP, obtaining the Euro NCAP Advanced reward.[11][12]


Collision Warning with Brake Support on the 2009 Lincoln MKS

2009 Ford introduced the Collision Warning with Brake Support on the Lincoln MKS and MKT and the Ford Taurus.[13] This system provides a warning through a Head Up Display that visually resembles brake lamps. If the driver does not react, the system pre-charges the brakes and increases the brake assist sensitivity to maximize driver braking performance. Ford demonstrated its Obstacle Avoidance technology relying on a mix of sensors, including a camera tucked behind the rearview mirror, to scan the road for vehicles and pedestrians and steer away if the driver does not take any action.[14]

General Motors[edit]

2012 GM's collision alert system is introduced in the GMC Terrain SUVs and uses a camera to provide warning when there is a vehicle ahead or there is a lane departure [15]

In 2013 the 2014 Chevrolet Impala received the radar and camera based Crash imminent braking (radar technology detects a possible crash threat and alerts the driver. If the driver does not appear to react quickly enough or doesn’t react at all, this feature intervenes to apply the brakes in an effort to avoid the crash. Forward collision alert, Lane departure warning, Side blind zone alert (Using radar sensors on both sides of the vehicle, the system “looks” for other vehicles in the blind zone areas of the Impala and indicates their presence with LED-lit symbols in the outside mirrors. Rear cross traffic alert features[16]


In 2003, Honda introduced the first pre-crash system with autonomous braking (Collision Mitigation Brake System CMBS, originally CMS) on the Inspire[17] and later in Acura, using a radar-based system to monitor the situation ahead and provide brake assistance if the driver reacts with insufficient force on the brake pedal after a warning in the instrument cluster and a tightening of the seat belts.[18][19] The Honda system was the first production system to provide automatic braking.[19] The 2003 Honda system also incorporated an "E-Pretensioner", which worked in conjunction with the CMBS system with electric motors on the seat belts. When activated, the CMBS has three warning stages. The first warning stage includes audible and visual warnings to brake. If ignored, the second stage would include the E-Pretensioner's tugging on the shoulder portion of the seat belt two to three times as an additional tactile warning to the driver to take action. The third stage, in which the CMBS predicts that a collision is unavoidable, includes full seat belt slack takeup by the E-Pretensioner for more effective seat belt protection and automatic application of the brakes to lessen the severity of the predicted crash. The E-Pretensioner would also work to reduce seat belt slack whenever the brakes are applied and the brake assist system is activated.[19]

In late 2004, Honda developed a night vision system that highlights pedestrians in front of the vehicle by alerting the driver with an audible chime and visually displaying them via HUD. The system only works in temperatures below 30 degrees Celsius (86 Fahrenheit). This system first appeared on the Legend.[20]


Hyundai Equus introduced "Vehicle Stability Management". VSM manages the function of all active and passive safety features. The VSM System incorporates electronic stability control (ESC), traction control (TCS), anti-lock breaking (ABS), electronic brake-force distribution (EBD), brake assist, and lane departure warning. This fully system also incorporates electronic parking brake, smart cruise control and seatbelt tensioning.


Mazda's Smart City Brake Support system uses lasers to detect vehicles or obstacles in front of the car.[21] The system is able to apply the brakes and cut engine power, and if the difference in speed between the car and the obstacle is 30 km/h (19 mph) or less, the system can avoid or at least lessen potential damage from a collision.


In 2002 Mercedes' "Pre-Safe" system was unveiled in the fall of at the Paris Motor Showon the 2003 S-Class. Using electronic stability control sensors to measure steering angle, vehicle yaw, and lateral acceleration and brake assist (BAS) sensors to detect emergency braking, the system can tighten the seat belts, adjust seat positions including rear seats (if installed), raise folded rear headrests (if installed), and close the sunroof if it detects a possible collision (including rollover).[22] A later version of the Pre-Safe system was supplemented by an additional function that can close any open windows if necessary.

In 2005 "Brake Assist BAS plus" was Mercedes-Benz's first forward warning collision system, introduced on the redesigned 2006 W221 S-Class,[23] incorporates the autonomous cruise control system and adds a radar-based forward collision warning.

In 2006, the "Pre-Safe Brake" on the CL-Class C216[24] was the first partial autonomous braking (40%, or up to 0.4g deceleration) if the driver does not react to the BAS Plus warnings and the system detects a severe danger of an accident.[25][26]

In 2009, Mercedes introduced the first Pre-Safe Brake with full autonomous braking with maximum braking force approximately 0.6 seconds before impact, on the Mercedes-Benz E-Class (W212).[27]

In 2011 occurred the introduction of the radar-based assistance system in the B-Class (as standard).[23]

In 2013 Mercedes updated Pre-Safe on the redesigned W222 S-Class as plus with Cross-Traffic Assist.[28] Pre-Safe with pedestrian detection and City Brake function is a combination of stereo camera and radar sensors to detect pedestrians in front of the vehicle. Visual and acoustic warnings are triggered when a hazard is spotted. If the driver then reacts by braking, the braking power will be boosted as the situation requires, up to a full brake application. Should the driver fail to react, Pre-Safe Brake triggers autonomous vehicle braking. Pedestrian detection is active up to approx. 72 km/h, and is able to prevent collisions with pedestrians autonomously from an initial speed of up to 50 km/h.[28] A radar sensor in the rear bumper monitors the traffic behind the vehicle. If the risk of an impact from the rear is detected, the rear hazard warning lights are activated to alert the driver of the vehicle behind (not on vehicles with USA/Canada coding). Anticipatory occupant protection measures, such as the reversible belt tensioners, are deployed. If the vehicle is stopped and the driver indicates a wish to remain stationary – by depressing the brake pedal, activating the HOLD function, or moving the selector lever to "P" – the system increases the brake pressure to keep the vehicle firmly braked during a possible rear-end collision.[28] Pre-Safe Impulse works an early phase of the crash, before the resulting deceleration starts to increase, the front occupants are pulled away from the direction of impact and deeper into their seats by their seat belts. By the time the accident enters the phase when loads peak, the extra distance they are retracted by can be used while dissipating energy in a controlled fashion. Pre-acceleration and force limitation allow the occupants to be temporarily isolated from the effects of the crash, significantly reducing the risk and severity of injuries in a frontal collision.[28]


Nissan's Infiniti brand offers both laser-based and radar-based systems.

Brake Assist with Preview: Preview function anticipates the need to apply emergency braking and pre-pressurize the brake system to help improve brake response.

Intelligent Brake Assist (IBA) with Forward Emergency Braking (FEB) (on QX80) uses radar to monitor approaching speed to the vehicle ahead, helping detect an imminent collision. It provides a two-stage warning to alert the driver, and if the driver takes no action, the system automatically engages the brakes to help reduce collision speed and impact.

Predictive Forward Collision Warning system warns the driver of risks that may be obscured from the driver's view. It senses the relative velocity and distance of a vehicle directly ahead, as well as a vehicle travelling in front of the preceding one.

Forward Emergency Braking: When the system judges that deceleration is required, it alerts the driver using both a screen display and sound, then generates a force that pushes the accelerator pedal up and smoothly applies partial braking to assist the driver in slowing the vehicle down. When the system judges that there is the possibility of a collision, it will automatically apply harder braking to help avoid a one.

Adaptive cruise control sensors provide data for precrash systems


2014: Renault introduced radar active emergency braking on 2015 Renault Espace[29]


Skoda introduced four new security system in 2013, alongside other car models of the VW group. The systems include Multi Collision Brake,[30] Crew Protect Assist, Lane Assistant and Front Assistant. The first Skoda model with these new systems was the Skoda Citigo in June 2012, along with the VW up! and the Seat Mii, the new Skoda Octavia (2013).


In 2008, Subaru introduced the ja:EyeSight (Japanese) system to Japanese drivers on the Legacy sedan, wagon and Outback, which, unlike radar-based systems, uses two CCD stereo cameras mounted to the roof beside the rear view mirror. This system also offers lane departure warning and adaptive cruise functions.[31] As of model year 2014, it is optional on the Legacy, Forester, or Impreza, and only on vehicles with the automatic or CVT transmission. In 2014 Subaru updated the system using cameras that can detect color (brake lights) and reducing the bulk of the system.[32]


2008 LS 600h forward PCS diagram, with radar (blue) and stereo camera (red) coverage

Toyota's "Pre-Collision System (PCS) was the first production forward collision warning system. The radar-based system that uses a forward-facing millimeter-wave radar. When the system determines that a frontal collision is unavoidable, it preemptively tightens the seat belts, removing any slack, and pre-charges the brakes using brake assist to give the driver maximum stopping power instantly when the driver depresses the brake pedal.

2003 February: Toyota launched PCS in on the redesigned Japanese domestic market Harrier

2003 August: added an automatic partial pre-crash braking system to the Celsior.[33]

2003 September: PCS made its first appearance in North America on the Lexus LS 430, becoming the first radar-guided forward collision warning system offered in the US.[34]

2004: In July 2004 the Crown Majesta Radar PCS added a single digital camera to improve the accuracy of collision forecast and warning and control levels[35][36][37]

2006: Pre-Collision System with the first Driver Monitoring System introduced in March 2006 on the Lexus GS 450h[35] using a CCD camera on the steering column. This system monitors the driver's face to determine where the driver is looking. If the driver's head turns away from road and a frontal obstacle is detected, the system will alert the driver using a buzzer, and if necessary, pre-charge the brakes and tighten the safety belts.

2006: the Lexus LS featured a further advanced version of the PCS. Advanced Pre-Collision System (APCS), added a twin-lens stereo camera located on the windshield and a more sensitive radar to detect for the first time smaller "soft" objects such as animals and pedestrians. A near-infrared projector located in the headlights allows the system to work at night. With the Adaptive Variable Suspension (AVS) and electric power steering, the system can change the shock absorber firmness, steering gear ratios, and torque assist to aid the driver's evasive steering measures. The lane departure warning system will make automatic steering adjustments to help ensure that the vehicle maintains its lane in case the driver fails to react. Driver Monitoring System was introduced on the Lexus LS. Rear-end Pre-Collision system includes a rearward-facing millimeter-wave radar mounted in the rear bumper.[38] This system adjusts the active head restraints by moving them upward and forward to reduce the risk of whiplash injuries if an imminent rear collision is detected.[39]

2008 Updated Driver Monitoring System added on the Crown for detecting whether the driver's eyes are properly open.[40] It monitors the driver's eyes to detect the driver's level of wakefulness. This system is designed to work even if the driver is wearing sunglasses, and at night.

2008 PCS with GPS-navigation linked brake assist function on the Crown. The system, which is designed to determine if the driver is late in decelerating at an approaching stop sign, will then sound an alert and can also pre-charge the brakes to provide optimum braking force if deemed necessary. This system works in certain Japanese cities and requires Japan specific road markings that are detected by a camera.

2009 on the redesigned Crown,[41] Toyota again further advanced the PCS, adding a front-side millimeter-wave radar to detect potential side collisions primarily at intersections or when another vehicle crosses the center line. The latest version tilts the rear seat upward, placing the passenger in a more ideal crash position if it detects a front or rear impact.[42]

2012: Higher Speed A-PCS on facelifted Lexus LS: enables deceleration of up to 37 MPH as compared to the current generation system of 25 MPH. This higher speed A-PCS uses the same technologies as the current A-PCS. This system increases the braking force up to twice that applied by average drivers. (Not available in U.S. markets due to regulatory considerations.

2013: Pre-Collision System with Pedestrian-avoidance Steer Assist and Steering Bypass Assist[43] can help prevent collisions in cases where automatic braking alone is not sufficient, such as when the vehicle is travelling too fast or a pedestrian suddenly steps into the vehicle’s path. An on-board sensor detects pedestrians and issues a visual alert on the dashboard immediately in front of the driver if the system determines that there is a risk of collision. If the likelihood of a collision increases, the system issues an audio and visual alarm to encourage the driver to take evasive action, and the increased pre-collision braking force and automatic braking functions are activated. If the system determines that a collision cannot be avoided by braking alone and there is sufficient room for avoidance, steer assist is activated to steer the vehicle away from the pedestrian.[44]


Laser sensor of VW Up

2010: "Front Assist" on the 2011 Volkswagen Touareg can brake to a stop in case of an emergency and tension the seat belts as a precautionary measure.[45]

2012: In 2012, Volkswagen Golf Mk7 introduced their "Proactive Occupant Protection", which will close the windows and retract the safety belts to remove excess slack if the potential for a forward crash is detected. Multi-collision brake system (Automatic Post-Collision Braking System) to automatically brake the car after an accident in order to avoid a second collision. City emergency braking automatically activates brakes at low speeds in urban situations.

2014: Volkswagen Passat B8 introduces pedestrian recognition a part of the system. It uses a sensor fusion between a camera and the radar sensor. There is an "emergency assist" in case of a non-reacting driver, the car takes the control of the brakes and the steering until a complete stop.


Volvo City Safety multiple camera

2006: Volvo's "Collision Warning with Auto Brake", developed in cooperation with Mobileye, was introduced on the 2007 S80. This system is powered by a radar/camera sensor fusion and provides a warning through a head up display that visually resembles brake lamps. If the driver does not react, the system pre-charges the brakes and increases the brake assist sensitivity to maximize driver braking performance. Later versions will automatically apply the brakes to minimize pedestrian impacts. In some models of Volvos, the automatic braking system can be manually turned off. The V40 also included the first pedestrian airbag.

2013: Volvo introduced the first cyclist detection system. All Volvo automobiles now come standard with a lidar laser sensor that monitors the front of the roadway, and if a potential collision is detected, the safety belts will retract to reduce excess slack. Volvo now includes this safety device as an optional in FH series trucks.[46]

2015: "IntelliSafe" with Auto brake at intersection. The Volvo XC90 is the first technology that features automatic braking if the driver turns in front of an oncoming car. This is a common scenario at busy city crossings as well as on highways, where the speed limits are higher.

List of cars with collision avoidance features available[edit]

See also[edit]


  1. ^
  2. ^ "Written question - Rear-end traffic collisions in the European Union - E-011477/2011". Retrieved 25 January 2015. 
  3. ^ "Answer to a written question - Rear-end traffic collisions in the European Union - E-011477/2011". Retrieved 25 January 2015. 
  4. ^
  5. ^
  6. ^ "Extensive safety in the new Audi A8. Bosch predictive emergency braking system goes into series production" (Press release). Retrieved 2 June 2010. 
  7. ^ "The new Audi A8" (Press release). Retrieved 17 February 2010. 
  8. ^ The new Audi Q7 – Sportiness, efficiency, premium comfort
  9. ^ "Cadillac ‘Virtual Bumpers’ Can Help Avoid Crashes". (Press release). Retrieved 25 January 2015. 
  10. ^ Chrysler Group LLC (2 June 2010). "All-new 2011 Jeep Grand Cherokee Earns 'Top Safety Pick' From the Insurance...". (Press release). Retrieved 25 January 2015. 
  11. ^ a b "City Brake Control wins the ‘Euro NCAP Advanced’ award". FGA EMEA Press site (Press release). June 26, 2013. Retrieved June 30, 2014. 
  12. ^ "Euro NCAP Advanced: FIAT City Brake Control". Euro NCAP official site. Retrieved June 30, 2014. 
  13. ^
  14. ^ "New Toyota, Ford Systems Can Steer Clear of Pedestrians". Retrieved 25 January 2015. 
  15. ^ "New Camera-Based Collision Alert Debuts on GMC Terrain". (Press release). Retrieved 25 January 2015. 
  16. ^
  17. ^ "Honda Announces a Full Model Change for the Inspire" (Press release). Honda. 2003-06-18. Retrieved 2015-01-19. 
  18. ^ "Honda Worldwide". (Press release). Retrieved 25 January 2015. 
  19. ^ a b c "Honda Worldwide - World News - News Releases - May 20, 2003". (Press release). Retrieved 25 January 2015. 
  20. ^
  21. ^ "MAZDA:Mazda to Feature Smart City Brake Support Advanced Safety Technology in All-New Mazda CX-5 Crossover SUV". (Press release). Retrieved 25 January 2015. 
  22. ^
  23. ^ a b Innovation as a tradition
  24. ^ Daimler Media: Innovation as a tradition
  25. ^
  26. ^ "Impact: Real Drivers. Life Changing Stories - Mercedes-Benz". Impact. Retrieved 25 January 2015. 
  27. ^ "Mercedes-Benz TecDay Special Feature: PRE-SAFE And PRE-SAFE Brake". (Press release). Retrieved 25 January 2015. 
  28. ^ a b c d "Extended PRE-SAFE protection: Prevention is better than cure". (Press release). May 2013. Retrieved 25 January 2015. 
  29. ^ "ADAS : a range of technologies promoting safety and easier driving experience". (Press release). Retrieved 25 January 2015. 
  30. ^ "Euro NCAP 2013 Award - Skoda Multi-Collision Brake". Retrieved 2013-04-17. 
  31. ^ Neff, John. "2013 Subaru models to see with optional EyeSight safety system". Autoblog. Retrieved 25 January 2015. 
  32. ^;jsessionid=BC4CE9E4A87FD0ABBF77D742AC4BBE54?&id=562&mid=1
  33. ^ "Safety matters: advanced crash avoidance technology finds its way into production vehicles in Japan". Automotive Industries. 2004. 
  34. ^
  35. ^ a b
  36. ^
  37. ^ (Really Playing it Safe)
  38. ^ "Toyota: News Releases". (Press release). Retrieved 25 January 2015. 
  39. ^
  40. ^ Toyota Enhances Pre-crash Safety System with Eye Monitor
  41. ^ "Toyota Launches Redesigned Crown Majesta in Japan". Worldcarfans. Retrieved 25 January 2015. 
  42. ^ Toyota Adds to Pre-crash Safety Technologies
  43. ^ "Toyota Global Site - Technology File". (Press release). Retrieved 25 January 2015. 
  44. ^ Toyota Develops New Pedestrian Safety Technology
  45. ^ "To the Point: The New Touareg. Volkswagen SUV is one of the safest automobiles of all times" (Press release). Retrieved 2 June 2010. 
  46. ^ "Volvo Trucks - Emergency braking at its best!". YouTube. Retrieved 25 January 2015. 
  47. ^ "Der neue NISSAN X-TRAIL – NISSAN crossovers-Fahrzeuge". Retrieved 25 January 2015. 

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