Electronic Stability Control Systems 1
Electronic Stability Control Systems
Delano Robinson
National (2007) IT Showcase
BDPA Bloomington-Normal
May 30, 2007
Introduction to Electronic Stability Control Systems (ESC)
In the near future when people hear the acronym ESC, it may be a reference to more than just the escape key on the keyboard of the computer. Car manufacturers and dealers could be talking about a safety feature expected to be in cars called the Electronic Stability Control System. An electronic stability control system is a new braking system designed to prevent rollovers by keeping your vehicle on the ground during dangerous situations. According to Robert Bosch GmbH Every year, 32,000 people die in traffic crashes in the U.S., and 2.6 million are injured. ESC is very effective when it comes to preventing crashes because it helps keep the vehicle in control during dangerous maneuvers and skidding. One of the major causes of serious crashes is rollovers. As ESC keeps the vehicle on the road it can also prevent many other serious crashes.
The most efficient protection against accidents would be to prevent them all together, however with an active safety system like ESC, Antilock Brakes and or Traction control systems accident can be prevented to a certain extent. When a vehicle accompanied by ESC incurs a complex situation such as sudden swerves to avoid certain obstacles, curves which have been underestimated and the change in road surfaces the system takes over and allow to the driver better chances to get through the situation. ESC comes from current technology we already have. ESC improves on the advantages of the Antilock Brake and Traction Control systems.
How Does ESC work?
ESC is full of mini computer chips that are working constantly as the driver drives. According to Robert Bosch GmbH ESC works instantly and the system also checks where the driver wants to steer versus where the vehicle is actually going 25 times per second. When ESC recognizes a critical situation ESC reacts faster than the human eye could blink. According to a representative from Chevrolet Automotives, the ESC System is a major way to improve vehicle stability during irregular maneuvers while on the road (“Chevy,” 2007). Below is an example from a car manufacture by the name of Continental Automotive Systems that shows how ESC Systems prevent rollovers.
Picture Explanation: The top portion of the picture shows an example of an under steer (Where the driver steers too little). The bottom portion shows an example of an over steer (Where the driver steers too much). The red in both images represents the car path without the Electronic Stability Control while the green in both images represents the car path with ESC.
Where Is ESC Now?
While electronic stability control systems are still in the developmental stages they can be expected to appear in cars as early as 2009; in hopes to assist with reducing the percentage of rollovers each year according to TRW media room (2006). Research has been completed which shows that ESC could have saved up to thirty-five percent of the deaths from 1997-2003 from single vehicle accident according to Dang of NHTSA (2004). According to news article from CNN.com titled New Vehicles to Offer Crash Prevention (2003), the ESC is a braking technology system that will become standard for all passenger vehicles sold in the United States. From researching this system, we can see that there could be many benefits for drivers, manufacturers, and the surroundings of the driver because the system is designed to improve the braking of our current vehicles. Even though ESC is still in its developmental stages TG Daily.com (2007) has stated that the vehicle safety feature is being worked on so that it could be sold as cheap as one hundred and eleven dollars.
Jennifer N. Dang’s Study and Analysis of the Effectiveness of ESC Systems
Studies have been done in advance to prove that ESC systems will and would have had a major impact on people’s lives and the death rates caused by rollovers and car accidents. The studies completed by Dang of NHTSA concerning ESC shows that the benefits and the rewards for drivers using the new system would be immaculate (2004). Also According to Dang (2004) the research that has been done shows that vehicles with ESC systems could have possibly prevented up to thirty-five percent of the single vehicle car crashes in the study. There are two tables from Dang that show the reduction of single vehicle accidents and the reduction of fatal single vehicle crash in passenger cars and SUVs.
Table 1: Effectiveness of ESC in Reducing Single Vehicle Crashes in Passenger Cars and SUVs
(1997-2002 crash data from five States)
No ESC / 1483 / 19444
ESC / 699 / 14090
Percent reduction in single vehicle crashes in passenger cars with ESC / 35.0 %
Approximate 95 percent confidence bounds / 29% to 41%
Chi-square value / 84.1
SUVs / Single Vehicle Crashes / Multi-Vehicle Crashes
No ESC / 512 / 6510
ESC / 95 / 3661
Percent reduction in single vehicle crashes in SUVs with ESC / 67.0 %
Approximate 95 percent confidence bounds / 60% to 74%
Chi-square value / 104.4
Table 2: Effectiveness of ESC in Reducing Fatal Single Vehicle Crashes in Passenger Cars and SUVs
(1997-2003 FARS data)
No ESC / 186 / 330
ESC / 110 / 278
Percent reduction in fatal single vehicle crashes in passenger cars with ESC / 30.0 %
Approximate 95 percent confidence bounds / 10% to 50%
Chi-square value / 6.0
SUVs / Fatal Single Vehicle Crashes / Fatal Multi-Vehicle Crashes
No ESC / 129 / 199
ESC / 25 / 103
Percent reduction in fatal single vehicle crashes in SUVs with ESC / 63.0 %
Approximate 95 percent confidence bounds / 44% to 81%
Chi-square value / 16.1
The equation below was used to calculate exactly how much electronic stability could have done for preventing accidents according to Dang of NHTSA (2004):
1 – {(699/1483)/(14090/19444)} = 35 percent
This calculation is where Dang of NHTSA estimated that electronic stability could have roughly saved thirty-five percent of the lives caused by single vehicle crashes in passenger cars and SUVs from 1997-2003 (2004).
What Are The Components Of ESC?
ESC is derived from a currently technology system we use today in current vehicles called the Anti-lock brake system (ABS). According to Robert Bosch GmbH the ESC system can be broken into this simple equation:
ESC = (ABS + Traction Control)2
ABS and traction control are features that can be found in most modern car today. The new components of ESC consist of wheel speed sensors, hydraulic modulator unit with attached ECU, steering angle sensors, communication with engine management, and a yaw-rate and lateral acceleration sensor.
What Are the Functions of ESC’s Components?
Wheel Speed Sensors
The wheel speed sensors are used by the ECU to compute the speeds of the all the wheels. Within the sensor there are two different principles used. The two principles used are active and passive speed sensors. According to Bosch the active sensor are becoming more and more widespread. The active sensors use a magnetic field for the contact less detection of the wheel speed and they are capable of recognizing the direction of rotation as well as a standstill according to Bosch.
Example Wheel Speed Sensor
Hydraulic modulator with attached ECU
The hydraulic modulator places the ECU’s command into use and control the pressure of the individual wheel brake cylinders by using the solenoid valves. According to Bosch the hydraulic modulator is located within the engine compartment between the brake master cylinder and the wheel brake cylinders. By placing the modulator here it keeps the hydraulic lines can be keep short. The modulator has input and output solenoid valves to control the pressure in the individual wheel brakes according to Bosch. ECU takes all electrical and electronic tasks as well as the control task of the vehicles systems.
Example Hydraulic modulator (With ECU)
Steering Angle Sensors
The complete task of the steering angle sensor is to measure the position of the steering by determining the angle according to Bosch. The driving steering angle sensors finds out the position the driver would like to be in and from there calculates where the driver should be with the vehicles speed and desired braking pressure.
Example Steering Angle Sensor
Communication with Engine Management
The data bus enables the ESC control unit to communicate with the engine control unit according to Bosch. In this way, the engine torque can be reduced if the driver accelerates too hard in a certain driving situation. The compartment also allows ESC to compensate for any excessive slipping provoked by the engine drag torque.
Example Communication with Engine Management system
Yaw-Rate and Lateral Acceleration Sensor
A yaw sensor records al the yawing movements of the vehicle around its vertical axis according to Bosch. Also according to Bosch by using the information from an integrated lateral-acceleration sensor, the status of the vehicle can be determined and compared to the driver’s wishes.
Example Yaw-Rate and Lateral Acceleration Sensor
ESC Systems Summary
With Technology increasing so rapidly the future could hold many exciting surprises. ESC system could possibly impact the lives of drivers and the driver’s surroundings in a major way with complex but yet simple technology in braking. The system is a new and improved form of anti-lock braking. Experts have broken the technology down in to the equation below according to Bosch:
ESC = (ABS + Traction Control)2
This equation basically tells normal people that ESC is a combination of the anti-lock braking system with added traction control, however we have already had these two technologies but ESC has made superior improvements to them. ESC works by constantly calculating the cars position and comparing that to where the car is actually supposed to be. If ESC detects a critical situation its able to react faster than the human eye can blink giving the driving a better chance to prevent accidents and crashes. The system provides an excellent service to it user by helping control all irregular maneuvers while on the road. The ESC system is made of five components; the components are the wheel speed sensors (4), a hydraulic modulator unit with an attached ECU, the steering angle sensors, communication with engine management, and a yaw-rate and lateral acceleration sensor. The ESC system is an affordable system that could be coming to cars as early as 2009 according to TRW media room.
References
Cheung, H. (2007, April). ESC required for all cars in 2012. Retrieved April 7, 2007, from http://www.tgdaily.com/index.php?option=com_content&task=view&id=31520
Continental Automotive Systems (2003). The Electronic Stability Control ESC. Retrieved April 15, 2007, from http://www.contionline.com/generator/www/de/en/cas/cas/themes/products/electronic_brake_and_safety_systems/electronic_brake_systems/abs_tcs_esc/esc_1003_en.html
Dang, J. (2004, September). Preliminary results analyzing the affectiveness of ESC systems, pp. 790-806. Retrieved April 15, 2007, from http://www.nhtsa.dot.gov/cars/rules/regrev/evaluate/809790.html
Ford, M. (2006). TRW/Goodyear create enhanced ESC system thanks to ‘Talking Tires’. Retrieved April 9, 2007, from http://trw.mediaroom.com/index.php?s=press_releases&item=106
Kurzweil, R. (2006) Interview with Unknown. Nov. 2006. C-Span2. Book Tv. Nov. 2006.
New vehicles to offer crash prevention. (2007, April). Retrieved April 13, 2007, from http://www.cnn.com/2007/AUTOS/04/05/crash_prevention/index.html
Robert Bosch GmbH. Retrieved May 14, 2007 from
http://www.bosch-escential.com/us/language1/schleudern.html
StabiliTrak electronic stability control system. (2007). Retrieved April 20, 2007, from http://www.chevrolet.com/pop/tahoe/2007/stabilitrak_en.jsp
The Associated Press (NY Times) (2007, April 14). System to Be In All New Cars By 2012. Retrieved April 10, 2007, from http://select.nytimes.com/gst/abstract.html?res=FB061EFC3C5B0C758CDDAD0894DF404482
Tyson, R. (2006, September). DOT Proposes anti-rollover technology for new vehicles, 09-06. Retrieved April 15, 2007, from http://www.nhtsa.gov/portal/site/nhtsa/template.MAXIMIZE/menuitem.f2217bee37fb302f6d7c121046108a0c/?javax.portlet.tpst=1e51531b2220b0f8ea14201046108a0c_ws_MX&javax.portlet.prp_1e51531b2220b0f8ea14201046108a0c_viewID=detail_view&javax.portlet.begCacheTok=token&javax.portlet.endCacheTok=token&itemID=2f07629c5f7ad010VgnVCM1000002c567798RCRD&viewType=standard&pressReleaseYearSelect=2006
Ulrich,L. (2003, October). The one car safety feature you need now. Retrieved April 17, 2007, from http://money.cnn.com/2003/09/25/pf/autos/what_is_esc/index.htm
ESC (2006). Wikipedia Open Source Info Retrieved April 17, 2007, from
http://www.answers.com/topic/electronic-stability-control