In 1983, a four-wheel electronic "Anti-Skid Control" system was introduced on the Toyota Crown. Mercedes-Benz, BMW, and Toyota introduced their first traction control systems in 1987. Traction control works by applying individual wheel braking and throttle to maintain traction under acceleration, but unlike ESC, it is not designed to aid in steering.
In 1990, Mitsubishi released the Diamante in Japan, which featured a system developed to help the driver maintain the intended line through a corner. This system monitored vehicle operating parameters through various sensors, and when too much throttle was used when taking a curve, engine output and braking were automatically regulated. Mitsubishi's TCL system had an active safety function that improved course tracing performance by automatically adjusting traction force, thereby restraining the development of excessive lateral acceleration while turning. Although not a 'proper' modern stability control system, its trace control monitored steering angle, throttle position, and individual wheel speeds. The TCL system's standard wheel slip control function enabled better traction on slippery surfaces or during cornering, and it worked together with the Diamante's electronically controlled suspension and four-wheel steering to improve total handling and performance.
BMW, working with Bosch and Continental, developed a system to reduce engine torque to prevent loss of control and applied it to most of the BMW model line for 1992, excluding the E30 and E36. This system could be ordered with the winter package, which came with a limited-slip differential, heated seats, and heated mirrors. From 1987 to 1992, Mercedes-Benz and Bosch co-developed a system called Elektronisches Stabilitätsprogramm ("Electronic Stability Program", trademarked as ESP) to control lateral slippage.
In 1995, three automobile manufacturers introduced ESC systems. Mercedes-Benz, supplied by Bosch, was the first to implement ESP with their Mercedes-Benz S 600 Coupé. Toyota's Vehicle Stability Control (VSC) system appeared on the Toyota Crown Majesta in 1995. General Motors worked with Delphi Automotive and introduced its version of ESC, called "StabiliTrak," in 1996 for the 1997 model year on select Cadillac models. StabiliTrak was made standard equipment on all GM SUVs and vans sold in the U.S. and Canada by 2007, except for certain commercial and fleet vehicles. The same year, Cadillac introduced an integrated vehicle handling and software control system called the Integrated Chassis Control System (ICCS) on the Cadillac Eldorado, which involved an omnibus computer integration of engine, traction control, StabiliTrak electronic stability control, steering, and adaptive continuously variable road sensing suspension (CVRSS).
In 1997, Audi introduced the first series production ESP for all-wheel drive vehicles with the Audi A8 and Audi A6 with quattro. In 1998, Volvo Cars began to offer their version of ESC called Dynamic Stability and Traction Control (DSTC) on the new Volvo S80.
During a moose test in October 1997, Swedish journalist Robert Collin of Teknikens Värld rolled a Mercedes A-Class (without ESC) at 78 km/h. Mercedes-Benz recalled and retrofitted 130,000 A-Class cars with firmer suspension and sportier tires, and all newly produced A-Class cars featured ESC as standard along with the upgraded suspension and wheels. This produced a significant reduction in crashes, and the number of vehicles with ESC rose. The availability of ESC in small cars like the A-Class ignited a market trend, thus ESC became available for all models.
Ford's version of ESC, called AdvanceTrac, was launched in the year 2000. Ford later added Roll Stability Control to AdvanceTrac, which was first introduced in the Volvo XC90 in 2003. Ford and Toyota announced that all their North American vehicles would be equipped with ESC as standard by the end of 2009. General Motors had made a similar announcement for the end of 2010.
In 2003 in Sweden, the purchase rate for new cars with ESC was 15%. Following a strong ESC recommendation from the Swedish road safety administration, by December 2004, the purchase rate had reached 69%, and by 2008 it had grown to 96%.
In 2009, the European Union decided to make ESC mandatory. Since November 1, 2011, EU type approval is only granted to models equipped with ESC. Since November 1, 2014, ESC has been required on all newly registered cars in the EU. The NHTSA required all new passenger vehicles sold in the US to be equipped with ESC as of the 2012 model year, estimating it would prevent 5,300–9,600 annual fatalities.
ESC intervenes only when it detects a probable loss of steering control, such as when the vehicle is not going where the driver is steering. This may happen, for example, when skidding during emergency evasive swerves, understeer or oversteer during poorly judged turns on slippery roads, or hydroplaning. ESC estimates the direction of the skid and then applies the brakes to individual wheels asymmetrically to create torque about the vehicle's vertical axis, opposing the skid and bringing the vehicle back in line with the driver's commanded direction. Additionally, the system may reduce engine power or operate the transmission to slow the vehicle down.
ESC can function on any surface, from dry pavement to frozen lakes. It reacts to and corrects skidding much faster and more effectively than the typical human driver, often before the driver is even aware of any imminent loss of control. For this reason, ESC systems typically alert the driver when they intervene, so that the driver is aware that the vehicle's handling limits have been reached. Most activate a dashboard indicator light and/or alert tone. All ESC manufacturers emphasize that the system is not a performance enhancement nor a replacement for safe driving practices, but rather a safety technology to assist the driver in recovering from dangerous situations. ESC does not increase traction, so it does not enable faster cornering, although it can facilitate better-controlled cornering. More generally, ESC works within the limits of the vehicle's handling and available traction between the tires and road. A reckless maneuver can still exceed these limits, resulting in loss of control.
Due to the fact that stability control can be incompatible with high-performance driving, many vehicles have an override control which allows the system to be partially or fully deactivated.
ESC systems often work to improve traction in off-road situations, in addition to their on-road duties. The effectiveness of traction control systems can vary significantly due to the significant number of external and internal factors involved at any given time, as well as the programming and testing performed by the manufacturer. In an open differential setup, power transfer takes the path of least resistance. In slippery conditions, this means when one wheel loses traction, power will counter-productively be fed to that axle instead of the one with higher grip. ESCs focus on braking wheels that are spinning at a rate drastically different from the opposing axle.
In intermediate level ESC systems, ABS will be disabled, or the computer will actively lock the wheels when brakes are applied. In these systems, or in vehicles without ABS, the performance in emergency braking in slippery conditions is greatly improved as grip state can change extremely rapidly and unpredictably off-road when coupled with inertia.
Many newer vehicles designed for off-road duties from the factory are equipped with Hill Descent Control systems to minimize the risk of runaway events occurring with novice drivers and provide a more consistent and safe descent than either no ABS or on-road-oriented ABS.
In some vehicles, ESC systems automatically detect whether to operate in off- or on-road mode, depending on the engagement of the 4WD system. Mitsubishi's Super-Select 4WD system, for example, automatically activates off-road traction control and disables ABS braking when shifted into 4WD High-range with the center differential locked, or 4WD Low-range with the center differential locked. Most modern vehicles with fully electronically controlled 4WD systems also automatically switch to an off-road-oriented mode of stability and traction control once low range, or certain terrain modes are manually selected.
Numerous studies around the world have confirmed that ESC is highly effective in helping the driver maintain control of the car, thereby saving lives and reducing the probability of occurrence and severity of crashes. In the fall of 2004, the American National Highway and Traffic Safety Administration (NHTSA) confirmed international studies, releasing results of a field study of ESC effectiveness in the USA. The NHTSA concluded that ESC reduces crashes by 35%. Additionally, SUVs with stability control are involved in 67% fewer accidents than SUVs without the system. The United States Insurance Institute for Highway Safety (IIHS) issued its own study in June 2006 showing that up to 10,000 fatal US crashes could be avoided annually if all vehicles were equipped with ESC. The IIHS study concluded that ESC reduces the likelihood of all fatal crashes by 43%, fatal single-vehicle crashes by 56%, and fatal single-vehicle rollovers by 77–80%.
ESC is described as the most important advance in auto safety by many experts. The European New Car Assessment Program (Euro NCAP) "strongly recommends" that people buy cars fitted with stability control. The IIHS requires that a vehicle must have ESC as an available option in order for it to qualify for their Top Safety Pick award for occupant protection and accident avoidance.
ESC incorporates yaw rate control into the anti-lock braking system (ABS). Anti-lock brakes enable ESC to slow down individual wheels. Many ESC systems also incorporate a traction control system (TCS or ASR), which senses drive-wheel slip under acceleration and individually brakes the slipping wheel or wheels and/or reduces excess engine power until control is regained.
The ESC system uses several sensors to determine where the driver intends to travel. Other sensors indicate the actual state of the vehicle. The control algorithm compares driver input to vehicle response and decides, when necessary, to apply brakes and/or reduce throttle. The ESC controller can also receive data from and issue commands to other controllers on the vehicle such as an all-wheel drive system or an active suspension system to improve vehicle stability and controllability.
The most important sensors are:
A steering wheel angle sensor that determines where the driver wants to steer.
A yaw rate sensor that measures the rotation rate of the car. The data from the yaw sensor is compared with the data from the steering wheel angle sensor to determine regulating action.
A lateral acceleration sensor that measures the vehicle's lateral acceleration.
Wheel speed sensors that measure wheel speed.
Other sensors can include a longitudinal acceleration sensor and a roll rate sensor.
ESC uses a hydraulic modulator to assure that each wheel receives the correct brake force. At the center of the ESC system is the electronic control unit (ECU), which contains various control techniques. The input signals are sent through an input circuit to the digital controller. The desired vehicle state is determined based upon the steering wheel angle, its gradient, and the wheel speed. Simultaneously, the yaw sensor measures the vehicle's actual yaw rate. The controller computes the needed brake or acceleration force for each wheel and directs the valves of the hydraulic modulator. The ECU is connected with other systems via a Controller Area Network interface to avoid conflicting with them.
Many ESC systems have an override switch so the driver can disable ESC, which may be used on loose surfaces such as mud or sand, or if using a small spare tire, which could interfere with the sensors. Some systems also offer an additional mode with raised thresholds, so that a driver can utilize the limits of their vehicle's grip with less electronic intervention. However, the ESC reactivates when the ignition is restarted.
While Sweden used public awareness campaigns to promote ESC use, others implemented or proposed legislation. The Canadian province of Quebec was the first jurisdiction to implement an ESC law, making it compulsory for carriers of dangerous goods in 2005. The United States followed, with the National Highway Traffic Safety Administration implementing FMVSS 126, which requires ESC for all passenger vehicles under 10,000 pounds. The regulation phased in starting with 55% of 2009 models and all 2012 and later models. Canada required all new passenger vehicles to have ESC from September 1, 2011. The Australian government announced on June 23, 2009, that ESC would be compulsory from November 1, 2011, for all new passenger vehicles sold in Australia. The European Parliament has also called for the accelerated introduction of ESC, with the European Commission confirming a proposal for the mandatory introduction of ESC on all new cars and commercial vehicle models sold in the EU from 2012, with all new cars being equipped by 2014. Argentina requires all new normal cars to have ESC since January 1, 2022. Chile requires all new cars to have ESC from August 2022. Brazil has required all new cars to have ESC from January 1, 2024.
The United Nations Economic Commission for Europe has passed a Global Technical Regulation to harmonize ESC standards. Global Technical Regulation No. 8 ELECTRONIC STABILITY CONTROL SYSTEMS was sponsored by the United States of America, and is based on Federal Motor Vehicle Safety Standard FMVSS 126. In Unece countries, approval is based on UN Regulation 140: Electronic Stability Control (ESC) Systems.
ESC is built on top of an anti-lock brake system, and all ESC-equipped vehicles are fitted with traction control. ESC components include a yaw rate sensor, a lateral acceleration sensor, a steering wheel sensor, and an upgraded integrated control unit. In the US, federal regulations have required that ESC be installed as a standard feature on all passenger cars and light trucks as of the 2012 model year. According to NHTSA research, ABS in 2005 cost an estimated US$368; ESC cost a further US$111. The retail price of ESC varies; as a stand-alone option it retails for as little as US$250. ESC was once rarely offered as a sole option, and was generally not available for aftermarket installation. Instead, it was frequently bundled with other features or more expensive trims, so the cost of a package that included ESC was several thousand dollars. Nonetheless, ESC is considered highly cost-effective and may pay for itself in reduced insurance premiums.
Availability of ESC in passenger vehicles has varied between manufacturers and countries. In 2007, ESC was available in roughly 50% of new North American models compared to about 75% in Sweden. However, consumer awareness affects buying patterns, so that roughly 45% of vehicles sold in North America and the UK were purchased with ESC, contrasting with 78–96% in other European countries such as Germany, Denmark, and Sweden. While few vehicles had ESC prior to 2004, increased awareness has increased the number of vehicles with ESC on the used car market.
ESC is available on cars, SUVs, and pickup trucks from all major automakers. Luxury cars, sports cars, SUVs, and crossovers are usually equipped with ESC. Midsize cars have also been gradually catching on. While traction control is usually included with ESC, there were vehicles that had traction control but not ESC. ESC was rare among subcompact cars in 2008.
In the UK, even mass-market superminis such as the Ford Fiesta Mk.6 and VW Polo Mk.5 came with ESC as standard. Elaborate ESC and ESP systems (including Roll Stability Control) are available for many commercial vehicles, including transport trucks, trailers, and buses from manufacturers such as Daimler, Scania, and Prevost. In heavy trucks, the ESC and ESP functions must be realized as part of the pneumatic brake system. Typical component and system suppliers are e.g. Bendix, and WABCO. ESC is also available on some motor homes.
Just as ESC is founded on the anti-lock braking system (ABS), ESC is the foundation for new advances such as Roll Stability Control or active rollover protection that works in the vertical plane much like ESC works in the horizontal plane. When RSC detects impending rollover, RSC applies brakes, reduces throttle, induces understeer, and/or slows down the vehicle. The computing power of ESC facilitates the networking of active and passive safety systems, addressing other causes of crashes. For example, sensors may detect when a vehicle is following too closely and slow down the vehicle, straighten up seat backs, and tighten seat belts, avoiding and/or preparing for a crash.
Moreover, current research on electronic stability control focuses on the integration of information from systems from multiple domains within the same vehicle, for example radars, cameras, lidars and navigation systems; and from other vehicles, road users and infrastructure. Consistently with the trend towards the implementation of forms of model-based and predictive control, such ongoing progress is likely to bring a new generation of vehicle stability controllers in the next few years, capable of pre-emptive interventions, e.g., as a function of the expected path and road curvature ahead.
Electronic stability control (ESC) is the generic term recognised by the European Automobile Manufacturers Association (ACEA), the North American Society of Automotive Engineers (SAE), the Japan Automobile Manufacturers Association, and other worldwide authorities. However, vehicle manufacturers may use a variety of different trade names for ESC.
ESC system manufacturers include: ```