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Not What You Meant?  There are 27 definitions for STC.  Also try: ESC or VSC or VDC or DSTC.

Electronic Stability Control

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Electronic Stability Control (ESC) is a computerized system designed to improve a vehicle's handling by intervening at the limits of traction and helping the driver maintain control of the vehicle. Robert Bosch GmbH and Mercedes Benz co-developed the first ESC system called Elektronisches Stabilitätsprogramm (ger."electronic stability programme" trademarked as ESP) for the flagship Mercedes-Benz S-Class sedan. ESC first came to general notice after a Mercedes-Benz A-Class car (without ESC) failed the moose test (sudden swerving to avoid an obstacle). Because Mercedes-Benz promotes its reputation for safety[1] Mercedes recalled and retrofitted 130,000 Mercedes-Benz A-Class cars with ESC. This produced a profound reduction in crashes[2]. Mercedes Benz licensed ESP/ESC for use by other vehicle manufacturers at no cost, including Volvo who added "DSA" as an option on all models and as standard in larger models in 1995. Mercedes-Benz became the first manufacturer to make ESC standard across its model range in 1999[3], with Volvo making its versions DSA, DSC and DSTC standard across all models on the release of new models between 1998-2000 as well as adding "EBD" (electronic brake force distribution) as standard on all models sold including existing models like the S/V40 in 1998. As of the 2008 model year, many manufactures still have yet to install ESC as standard on all models. For example, ESC is not available for the Honda Fit[4] or the Ford Focus[5]. ESC was introduced to the mass market by Robert Bosch GmbH/Mercedes-Benz, Continental Automotive Systems, Delphi and TRW. Electronic Stability Control is the generic term recognized by the Society of Automotive Engineers and other authorities, although vehicle manufacturers use a variety of different trade names (see below).

Contents

Operation

ESC compares the driver's intended direction (by measuring steering angle) to the vehicle's actual direction (by measuring lateral acceleration, rotation (yaw) and individual wheel speeds). If the vehicle is not going where the driver is steering, ESC then brakes individual front or rear wheels and/or reduces excess engine power as needed to help correct understeer (plowing) or oversteer (fishtailing). ESC incorporates yaw angle control into anti-lock brakes. Yaw is rotation around the vertical axis; i.e. spinning left or right. Anti-lock brakes enable ESC to brake individual wheels. ESC may also incorporate traction control, 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. ESC cannot override a car's physical limits. If a driver pushes the possibilities of the car's chassis and ESC too far, ESC cannot prevent a crash. It is a tool to help the driver maintain control.

Effectiveness

Numerous international studies have confirmed the effectiveness of ESC in helping the driver maintain control of the car and helping to save lives and reduce the severity of crashes. In the fall of 2004 in the U.S., the National Highway and Traffic Safety Administration confirmed the international studies, releasing results of a field study in the U.S. of ESC effectiveness. NHTSA concluded that ESC reduces crashes by 35%. Additionally, sport utility vehicles with stability control are involved in 67 percent fewer accidents than SUVs without the system. The Insurance Institute for Highway Safety (IIHS) issued its own study results in 2004 concluding that universal use of ESC could save 7,000 lives a year in the United States. In June 2006, the IIHS released a second study showing that up to 10,000 fatal US crashes could be avoided annually if all vehicles were equipped with ESC[6] The 2006 study concluded that ESC reduces the likelihood of all fatal crashes by 43 percent, fatal single-vehicle crashes by 56 percent, and fatal single-vehicle rollovers by 77-80 percent. ESC is described as the most important advance in auto safety since the seat belt by many experts[7] including Nicole Nason,[8] Administrator of the NHTSA,[9] Jim Guest and David Champion[10] of Consumers Union[11] Max Mosley of the Fédération Internationale de l'Automobile (FIA), E-Safety Aware[12], Csaba Csere, editor of Car and Driver[13], and Bill Kozyra, CEO of Continental Automotive Systems[9]. The European New Car Assessment Program (EuroNCAP) "strongly recommends" that people buy cars fitted with stability control.[14] On November 21, 2006 the IIHS announced that 13 of the 2007 vehicles had earned its TOP SAFETY PICK rating — although the rating is based primarily on crashworthiness, a major new requirement for this top rating is that the vehicle must be equipped with ESC (which helps avoid crashes)[15].

Cost

ESC is built on top of an anti-lock brake (ABS) system. The ESC components include a Yaw rate sensor, a Lateral Acceleration Sensor, a Steering Wheel Sensor, and an upgraded Integrated Control Unit. According to National Highway Traffic Safety Administration research, ABS costs an estimated US$368 (in 2005) and ESC costs an additional US$111. The retail price of ESC varies; as a stand-alone option, it retails for as little $450. Unfortunately, many auto makers bundle ESC with other features so the cost of a package that includes ESC could be several thousands of dollars. Research shows that ESC is highly cost-effective[16] and it might pay for itself in reduced insurance premiums.

Availability

Although Mercedes Benz recalled and retro-fitted the fleet of Mercedes-Benz A-Class cars with ESC in 1995, ESC is not generally available for after-market installation. The only way consumers can get ESC is to buy a vehicle equipped by the manufacturer with standard or optional ESC. Availability of ESC in passenger vehicles varies from between manufacturers and countries. In 2007, ESC was available in roughly 50% of new North American models, whereas that figure is about 75% in Sweden. However, consumer awareness affects buying patterns so that roughly 45% of vehicles sold in North America and the UK are purchased with ESC[17], contrasting with 78-93% in Nordic European countries such as Germany, Denmark, and Sweden. While few vehicles had ESC prior to 2004, increased awareness will increase the number of vehicles with ESC on the used car market. ESC is available on cars, SUV's, and pickup trucks from all major auto makers. ESC is also available on some motor homes. Elaborate ESC and ESP systems (including Roll Stability Control (RSC)[18]) are available for many commercial vehicles[19], including transport trucks, trailers, and buses from manufacturers such as Bendix Corporation[20], WABCO [21], Daimler Chrysler,[22], Scania AB[23], and Prevost[24]

Components and Design

The ESC-system uses several sensors to determine the state the driver wants the vehicle to be in (driver demand). Other sensors indicate the actual state of the vehicle (vehicle response). The control-algorithm compares both states and decides, when necessary, to adjust the dynamic state of the vehicle. The sensors used for ESC have to send data at all times in order to detect possible defects as soon as possible. They have to be resistant to possible forms of interference (rain, holes in the road, etc.). The most important sensors are:

  • Steering wheel angle sensor : determines the driver's intended rotation; i.e. where the driver wants to steer. This kind of sensor is often based on AMR-elements.
  • Yaw sensor : measures the yaw angle (rotation) of the car; i.e how much the car is actually turning. The data from the yaw sensor is compared with the data from the steering wheel angle sensor to determine regulating action.
  • Lateral acceleration sensor : often based on the Hall effect. Measures the lateral acceleration of the vehicle.
  • Wheel speed sensor : measures the wheel speed.

ESC uses a hydraulic modulator to assure that each wheel receives the correct brake force. A similar modulator is used in ABS. ABS needs to reduce pressure during braking, only. ESC additionally needs to increase pressure in certain situations. The heart of the ESC-system is the ECU. The various control techniques are embedded in it. Often, the same ECU is used for diverse systems at the same time (ABS, Traction control, climate control, etc.). The input signals are sent through the 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 actual state. The controller computes the needed brake or acceleration force for each wheel and directs via the driver circuits the valves of the hydraulic modulator. Via a CAN-interface the ECU is connected with other systems (ABS, etc.) in order to avoid giving contradictory commands.

Criticism

Some people contend (backed up by the theory of risk compensation) that the perception of safety conferred by the ESC will encourage more dangerous driving or risk taking. The Partnership for Safe Driving is among those concerned that ESC is just the latest example of a long and ultimately unsuccessful campaign, in the U.S. and abroad, to make cars that are capable of compensating for dangerous driving behavior[25] The Partnership believes that if no corresponding effort is made to deter speeding, aggressive, distracted and drowsy driving, this technology will not live up to its promise and may, in fact, encourage even more dangerous driving behavior. The counter-argument is that most road users do not understand these systems and hence just drive as they normally would. Also, a flashing light on the dash (in most ESC-equipped cars) tells drivers when the ESC system is active, warning them to slow down when their vehicle is skidding. Further, statistics from manufacturers such as ESC pioneer, Mercedes Benz, clearly show the decrease in road accidents after the introduction of the technology[26]. Some argue that, with ESC, very dangerous drivers will be able to drive faster before traction limits are reached, so when the vehicle loses control, it will happen at higher speeds, causing more severe crashes. However, this is not possible because ESC only applies brakes and/or reduces power and does not increase the traction limit of the vehicle. Therefore a vehicle with ESC cannot be pushed faster through a corner than a vehicle without ESC. Because ESC applies brakes and/or reduces engine power, it tends to slow the vehicle down when it reaches traction limits and typically prevents the vehicle from surpassing traction limits. Some driving enthusiasts object to some of the implementations of ESC.[attribution needed] They contend that by making it impossible to explore the dynamic behavior of their cars, overzealous ESC systems spoil much of the fun of driving. Most manufacturers allow drivers to switch off ESC systems, and some use ESC systems that allow greater levels of understeer or oversteer before it intervenes. Some even provide a setting so the user can choose whether the system will intervene earlier or later stage. Enthusiasts have also begun to modify ESC systems to suit their preferred driving styles[27]. The real purpose of the switch is so vehicles stuck in mud or a snowdrift can temporarily disable ESC (which cuts engine power and makes it difficult to rock the vehicle back and forth) until they are back on the road. The switch automatically defaults back to the ESC-on setting when the ignition is re-started. Some people worry that ESC will make drivers overconfident, too relaxed, or too reliant on ESC. This same argument could apply to radial tires, good suspension designs, or other automotive innovations. Others complain that ESC causes loss of driver control, particularly by allowing computers to control the vehicle.[attribution needed] However, ESC, like any handling aid, actually gives drivers greater control; to do what ESC does would require four brake pedals, four feet, and super-human reactions. Also, computers already control many vehicle functions. The fact that ESC was quickly adopted by manufacturers of performance vehicles and now comes standard on all Ferrari, Porsche, and Lamborghini cars is a good proof for that. It has also been argued that ESC is being used as a "catch all" for poorly designed cars, whereby the basic mechanical handling of a car is unstable and ESC is used to compensate for the problem.[attribution needed] However, except in the case of low-end economy cars, and the Mercedes A class, this argument is largely without merit, as high-end performance and/or safety oriented brands like BMW, Ferrari, Mercedes, and Volvo were among the first to adopt ESC. In the event that the vehicle is out of alignment, has dissimilar sized left/right tires fitted, or has a tire with low enough air pressure to affect the steering wheel angle, the yaw rate sensor would conflict with the steering wheel sensor. If this were the case, the vehicle's Powertrain Control Module may interpret the driver's actions as trying to turn the vehicle, rather than compensation for a mechanical problem. However, ECU programmers are familiar with this type of issue, and use cross-correlation between sensors to identify problems. Overall, ESC systems have resulted in a marked drop in accident rates, overriding most arguments against its implementation[28]. Perhaps the harshest criticism surrounding ESC has been the reluctance of some manufacturers to fit it as standard across all of their models. Some manufacturers have restricted ESC fitment to high-end models, encouraging buyers to purchase luxury features they don't need in order to get ESC. Given the cost-effectiveness of ESC in reducing crashes and saving lives, some safety advocates have accused manufacturers of cynical marketing. Because ESC costs so little, some critics ask, "Aren't poor people entitled to safety?" One representative at the Choose ESC! campaign launch quipped, "it would be inconceivable if seat belts were only available for an extra charge, or exclusively in expensive cars."[29] However, manufacturers are moving toward installation of ESC in all vehicles in response to growing public awareness and anticipated government legislation. Safety advocates have also criticized governments for being slow to mandate ESC on all vehicles, arguing that ESC not only protects occupants of ESC-equipped vehicles, but also all other users of the road, because ESC-equipped vehicles are less likely to lose control and hit them. New vehicles purchased without ESC may remain on the road for the next 15-25 years. Viviane Reding of the European Commission said, "Time is short. Each new car that is sold without ESC is a lost opportunity to save lives and reduce suffering."[30]

Product names

Vehicle manufacturers use electronic stability control systems under different marketing names:

  • Acura: Vehicle Stability Assist (VSA)
  • Alfa Romeo: Vehicle Dynamic Control (VDC)
  • Audi: ESP - Electronic Stabilization Program
  • Buick: StabiliTrak
  • BMW: Dynamic Stability Control (DSC), including Dynamic Traction Control
  • Cadillac: All-Speed Traction Control & StabiliTrak
  • Chevrolet: StabiliTrak; Active Handling (Corvette only)
  • Chrysler: Electronic Stability Program (ESP)
  • Citroën: Electronic Stability Program (ESP)
  • Daewoo: Traction Control System (TCS)
  • Dodge: Electronic Stability Program (ESP)
  • Daimler: Electronic Stability Program (ESP)
  • Fiat: Electronic Stability Program (ESP) and Vehicle Dynamic Control (VDC)
  • Ferrari: Controllo Stabilità (CST)
  • Ford: AdvanceTrac with Roll Stability Control (RSC) and Interactive Vehicle Dynamics (IVD) and Electronic Stability Program (ESP); Dynamic Stability Control (DSC) (Australia only)
  • General Motors: StabiliTrak
  • Honda: Electronic Stability Control (ESC) and Vehicle Stability Assist (VSA) and Electronic Stability Program (ESP)
  • Holden: Electronic Stability Program (ESP)
  • Hyundai: Electronic Stability Program (ESP), Electronic Stability Control (ESC), and Vehicle Stability Assist (VSA)
  • Infiniti: Vehicle Dynamic Control (VDC)
  • Jaguar: Dynamic Stability Control (DSC)
  • Jeep: Electronic Stability Program (ESP)
  • Kia: Electronic Stability Program (ESP)
  • Land Rover: Dynamic Stability Control (DSC)
  • Lexus: Vehicle Dynamics Integrated Management (VDIM) with Vehicle Stability Control (VSC) and Traction Control (TRAC) systems
  • Lincoln: AdvanceTrac
  • Maserati: Maserati Stability Program (MSP)
  • Mazda: Dynamic Stability Control (DSC)
  • Mercedes-Benz (inventors): Electronic Stability Program (ESP)
  • Mercury: AdvanceTrac
  • MINI: Dynamic Stability Control
  • Mitsubishi: Active Skid and Traction Control MULTIMODE and Active Stability Control (ASC) (Australia only)
  • Nissan: Vehicle Dynamic Control (VDC)
  • Oldsmobile: Precision Control System (PCS)
  • Opel: Electronic Stability Program (ESP)
  • Peugeot: Electronic Stability Program (ESP)
  • Pontiac: StabiliTrak
  • Porsche: Porsche Stability Management (PSM)
  • Renault: Electronic Stability Program (ESP)
  • Rover: Dynamic Stability Control (DSC)
  • Saab: Electronic Stability Program
  • Saturn: StabiliTrak
  • SEAT: Electronic Stability Program (ESP)
  • Škoda: Electronic Stability Program (ESP)
  • Smart: Electronic Stability Program (ESP)
  • Subaru: Vehicle Dynamics Control Systems (VDCS)
  • Suzuki: Electronic Stability Program (ESP)
  • Toyota: Vehicle Dynamics Integrated Management (VDIM) with Vehicle Stability Control (VSC)
  • Vauxhall: Electronic Stability Program (ESP)
  • Volvo: Dynamic Stability and Traction Control (DSTC)
  • Volkswagen: Electronic Stability Program (ESP)

System Manufacturers

ESC system manufacturers include:

Future

Electronic Stability Control forms the foundation for new advances on vehicle equipment (such as roll stability control - RSC) that will save additional lives and give the driver still more control over the vehicle. The computing power of ESC facilitates the networking of active and passive safety systems on the car, creating the opportunity to address still more causes of crashes. The market for this system is growing at a very robust rate, especially in European countries such as Sweden and Germany. For example, in Sweden, in 2003, the purchase rate on new cars with ESC was 15%. The Swedish road safety administration issued a strong ESC recommendation and in September 2004, 16 months later, the purchase rate was 58%. A stronger ESC recommendation was then given and in December 2004, the purchase rate on new cars had reached 69%[31] and by 2007 it had grown to 93%. In the US, the NHTSA has mandated that ESC be included on every new light (under 10,000 lbs) vehicle by the model year 2012 (September, 2011), phasing in ESC starting with 55% of 2009 vehicles, 75% of 2010 vechiles, 95% of 2011 vehicles and finally 100% of 2012 vehicles[32]. Canada is expected to "pre-publish" in 2008 a regulation mandating ESC by about 2012. It is expected that ESC will be installed by 2015 in most new vehicles sold in most European countries, Australia, New Zealand, in Japan. China, India, and mid-Eastern countries are also considering ESC. Several major auto makes have announced their intention to equip all their passenger vehicles with ESC within the next few years.

See also

References

  1. ^ Reduction in Road Death Need in 10 Years, <http://news.mercedes-benz.co.uk/article-494/innovations/reduction-in-road-deaths-need-in-10-years.html>. Retrieved on 2007-12-28
  2. ^ Fahrunfalle: Dank ESP verunglucken Mercedes-Personenwagen seltener, <http://www.whnet.com/4x4/pix/esp_stat.jpg>. Retrieved on 2007-12-28
  3. ^ 1999 Mercedes M-Class Sport Utility Vehicles Feature Continental Teves- Supplied Electronic Stability Program Plus Other Electronic Chassis And Braking System, <http://www.whnet.com/4x4/esp_pr99.html>. Retrieved on 2007-12-28
  4. ^ 2008 Honda Fit Features and Specs, <http://autos.msn.com/research/vip/spec_safety.aspx?year=2008&make=Honda&model=Fit&trimid=-1>. Retrieved on 2007-12-28
  5. ^ 2008 Ford Focus Features and Specs, <http://autos.msn.com/research/vip/spec_safety.aspx?year=2008&make=Ford&model=Focus&trimid=-1>. Retrieved on 2007-12-28
  6. ^ http://www.iihs.org/news/rss/pr061306.html
  7. ^ EU Commission, FIA, And Euro NCAP Recommend — 'No Car Without ESP', <http://www.carpages.co.uk/news/esp-09-05-07.asp>. Retrieved on 2007-12-28
  8. ^ U.S. to Require Anti-Rollover Technology on New Cars by 2012, <http://www.insurancejournal.com/news/national/2006/09/15/72448.htm>. Retrieved on 2007-12-28
  9. ^ a b U.S. set to mandate Anti-Rollover Technology vehicles, <http://www.cbc.ca/news/story/2006/09/13/auto-stability.html>. Retrieved on 2007-12-28
  10. ^ Stability system called the best thing since seat belts, <http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2006/06/13/MNG7UJD1451.DTL>. Retrieved on 2007-12-28
  11. ^ Consumer Reports 2007 Annual Report, <http://www.consumerreports.org/cro/resources/streaming/PDFs/2007annualreport.pdf>. Retrieved on 2007-12-28
  12. ^ http://www.esafetyaware.eu/download/related_documents/esafetyaware_flyer.pdf
  13. ^ The Greatest Advance in Safety Since Seatbelts, <http://www.caranddriver.com/columns/9036/the-greatest-advance-in-safety-since-seatbelts.html?al=128>. Retrieved on 2007-12-28
  14. ^ http://www.euroncap.com/content/safety_ratings/recommendation.php
  15. ^ http://www.iihs.org/news/rss/pr112106.html
  16. ^ http://www.chooseesc.eu/download/press/University%20of%20Cologne_ESC_cost_benefit.pdf
  17. ^ http://www.thatcham.org/esc/
  18. ^ http://www.esafetysupport.org/en/learn_about_esafety_systems/esafety_systems/roll_stability_control_system_rsc.htm
  19. ^ http://www.bendix.com/Lists/Bendix%20News/Attachments/122/Bendix_ESP_update.pdf
  20. ^ http://www.bendix.com/en-us/products/abs/Pages/ABS6.aspx
  21. ^ http://www.meritorwabco.com/rsc.asp
  22. ^ http://articles.jimtrade.com/1/69.htm
  23. ^ http://www.scania.ie/bus_coach/technology/eps/
  24. ^ http://www.prevostcar.com/cgi-bin/pages.cgi?page=sh_esp_passenger
  25. ^ http://www.crashprevention.org
  26. ^ http://www.nhtsa.dot.gov/portal/site/nhtsa/menuitem.012c081c5966f0ca3253ab10cba046a0/
  27. ^ http://autospeed.drive.com.au/cms/A_2199/article.html
  28. ^ http://www.nhtsa.dot.gov/portal/site/nhtsa/menuitem.012c081c5966f0ca3253ab10cba046a0/
  29. ^ http://www.bosch-presse.de/TBWebDB/en-US/PressText.cfm?&Search=1&id=3114
  30. ^ http://ec.europa.eu/commission_barroso/reding/docs/speeches/rome_20070508.pdf
  31. ^ http://www.vv.se/filer/30825/11_1_antisladdsystem.pdf
  32. ^ http://www.consumeraffairs.com/news04/2006/09/nhtsa_stability.html

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