What is ABS in modern car.How does it work?

Question

What is ABS in modern car.How does it work?

Answer 1

An antilock braking system works with the regular or foundation brakes on your vehicle. ABS simply keeps your base brakes from locking up. In vehicles not equipped with ABS, the driver can manually pump the brakes to prevent wheel lockup. In vehicles equipped with ABS, the driver's foot remains firmly on the brake pedal, allowing the system to automatically pump the brakes.

What ABS does is similar to a person pumping the brakes. It automatically changes the pressure in your car's brake lines to maintain maximum brake performance just short of locking up the wheels. ABS does this very rapidly with electronics.

Answer 2

ABS is a computer operated braking system which prevents the brakes from locking up in a panic stop situation.  The brakes will automatically pump themselves to stop you safely rather that having the car go into a skid or slide as would happen if the brakes locked up completely.  Basically, the ABS will keep the vehicle going straight.

Answer 3

ok ABS or anti lock braking system is the property of brakes to prevent wheel lock wait i will make u understand in easy language.suppose u r drivin' a car.then comes an unfortunate situation in  which u put sudden brakes.the sudden brakes will NOT stop the car but it will stop the wheels i.e. the wheels will stop rotating but the car will move forward a bit due to momentum.after that the car will skid ahead resulting in a crash.to stop this usual action of cars without ABS the latter(ABS) has been introduced.in this ,whenever u put sudden brake,the cars wheel will not stop rotating but will slow to an extent of stopping and until it will stop the brake will release even if the brake pedal is kept pressed.then this same process will take place every 6 milliseconds (1 second = 60 milliseconds) and the car will eventually come to stop before the place where the car without ABS would stop.ANTI-LOCK BRAKE refers to not locking of wheels due to brakes.it use many complicated computerised unit which monitor braking system and levels.with the invention of this has lead to further new technologies like ANTI-SLIP REGULATION,ELECTRONIC BRAKE-FORCE DISTRIBUTION,BRAKE ASSIST,etc.

Answer 4

An anti-lock braking system (ABS) is a safety system on motor vehicles which prevents the wheels from locking while braking.

You'll find a lot of info on ABS systems (some of it is quoted above) at Wikipedia: http://en.wikipedia.org/wiki/Anti-lock_b...

Answer 5

ABS (ANTILOCK BRAKING SYSTEM)

systems use a combination of electronic and hydraulic systems to modulate the brakes individually to prevent them from locking up. Antilock systems basically consist of wheel speed sensors, a hydraulic control unit (HCU), and an electronic control unit (ECU).

During braking the wheel speed sensors measure the rotational speed of the wheels and forward this information to the ECU. If the ECU determines that one wheel is decelerating at a much greater rate than another (indicating that the brake is about to lock), the ECU directs solenoid valves in the HCU to open to release hydraulic pressure to the brake until the rotational speed of the errant wheel matches the others.

Because of the complexity of the system, when the engine is started, a self-test sequence occurs. If the check is successful, the ANTILOCK and BRAKE lights will extinguish. If some component fails to check out, one or both lights will remain lit. One or both warning lights may also come on while driving, also indicating a problem. If just the ANTILOCK warning light comes on, some ABS component has failed, but the car still has power-assisted brakes. If both the ANTILOCK and BRAKE lights come on, the car is without power-assisted brakes, which is very dangerous. If just the BRAKE warning light comes on, this may be caused by low brake fluid or worn brake pads.

Answer 6

ABS is Anti-Locking Brakes. It prevents the wheels from locking when you apply the brakes.

A typical ABS is composed of a central electronic control unit (ECU), four wheel speed sensors (one for each wheel), and two or more hydraulic valves within the vehicle brake circuit. The ECU constantly monitors the rotational speed of each wheel. When it senses that any number of wheels are rotating considerably slower than the others (a condition that is likely to bring it to lock - see note below), it actuates the valves to decrease the pressure on the specific braking circuit for the individual wheel, effectively reducing the braking force on that wheel. The wheel(s) then turn faster; when they turn too fast, the force is reapplied. This process is repeated continuously, and this causes the characteristic pulsing feel through the brake pedal. A typical anti-lock system can apply and release braking pressure up to 20 times a second.

Answer 7

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Answer 8

An anti-lock braking system (ABS) (translated from German, Anti-Blockier System) is a safety system on motor vehicles which prevents the wheels from locking while braking.

A rotating road wheel allows the driver to maintain steering control under heavy braking, by preventing a locked wheel or skid, and allowing the wheel to continue to forward roll and create lateral control, as directed by driver steering inputs. Disadvantages of the system include increased braking distances under some limited circumstances (ice, snow, gravel, "soft" surfaces), and the creation of a "false sense of security" among drivers who do not understand the operation, and limitations of ABS.

Since it came into widespread use in production cars (with "version 2" in 1978), ABS has made considerable progress. Recent versions not only handle the ABS function itself (i.e. preventing wheel locking under braking), but also electronic control of the front-to-rear bias known as electronic brakeforce distribution (EBD), traction control system (TCS or ASR), an "emergency" brake assist (BA, EBA or HBA), and electronic stability control (ESP, ESC or DSC), amongst others.

History

Anti-lock braking systems were first developed for aircraft in 1929, by the French automobile and aircraft pioneer, Gabriel Voisin, as threshold braking an airplane is nearly impossible. An early system was Dunlop's Maxaret system, introduced in the 1950s and still in use on some aircraft models.

A fully mechanical system saw limited automobile use in the 1960s in the Ferguson P99 racing car, the Jensen FF and the experimental all wheel drive Ford Zodiac, but saw no further use; the system proved expensive and, in automobile use, somewhat unreliable. However, a limited form of anti-lock braking, utilizing a valve which could adjust front to rear brake force distribution when a wheel locked, was fitted to the 1964 Austin 1800.



ABS brakes on a BMW motorcycleChrysler, together with the Bendix Corporation, introduced a crude, limited production ABS system on the 1971 Imperial. Called "Sure Brake", it was available for several years, and had a satisfactory performance and reliability record. Ford also introduced anti lock brakes on the Lincoln Continental Mark III and the Ford LTD station wagon, called "Sure Trak". The German firms Bosch and Mercedes-Benz had been co-developing anti-lock braking technology since the 1930s, and introduced the first completely electronic 4-wheel multi-channel ABS system in trucks and the Mercedes-Benz S-Class in 1978. ABS Systems based on this more modern Mercedes design were later introduced on other cars and motorcycles. General Motors introduced the "Trackmaster" ABS on their Cadillac models in 1971 as an option that was operational on the rear wheels for RWD models

In 1988 BMW became the world's first motorcycle manufacturer to introduce an electronic/hydraulic ABS system, this on their BMW K100. In 1992 Honda launched its first ABS system, this on the ST1100 Pan European. In 1997 Suzuki launched its GSF1200SA (Bandit) with ABS.

Operation

The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake).

A typical ABS is composed of a central electronic control unit (ECU), four wheel speed sensors (one for each wheel), and two or more hydraulic valves within the vehicle brake circuit. The ECU constantly monitors the rotational speed of each wheel. When it senses that any number of wheels are rotating considerably slower than the others (a condition that is likely to bring it to lock - see note below), it actuates the valves to decrease the pressure on the specific braking circuit for the individual wheel, effectively reducing the braking force on that wheel. The wheel(s) then turn faster; when they turn too fast, the force is reapplied. This process is repeated continuously, and this causes the characteristic pulsing feel through the brake pedal. A typical anti-lock system can apply and release braking pressure up to 20 times a second.

Note: The ECU needs to determine when some of the wheels turn considerably slower than any of the others because when the car is turning the two wheels towards the center of the curve inherently move slightly slower than the other two – which is the reason why a differential is used in virtually all commercial cars.

The sensors can become contaminated with metallic dust, or other contaminants, and fail to correctly detect wheel slip; this is not always picked up by the internal ABS controller diagnostic.[citation needed] In this occurrence, the ABS warning light will usually be illuminated on the instrument panel, and the ABS will be disabled until the fault is rectified.

[edit] Additional developments

Modern Electronic Stability Control (ESC or ESP) systems are an evolution of the ABS concept. Here, a minimum of two additional sensors are added to help the system work: these are a steering wheel angle sensor, and a gyroscopic sensor. The theory of operation is simple: when the gyroscopic sensor detects that the direction taken by the car does not coincide with what the steering wheel sensor reports, the ESC software will brake the necessary individual wheel(s) (up to three with the most sophisticated systems), so that the vehicle goes the way the driver intends. The steering wheel sensor also helps in the operation of Cornering Brake Control (CBC), since this will tell the ABS that wheels on the inside of the curve should brake more than wheels on the outside, and by how much.

[edit] Traction control

Main article: Traction control system

The ABS equipment may also be used to implement traction control system (TCS, ASR) on acceleration of the vehicle. If, when accelerating, the tire loses traction, the ABS controller can detect the situation and take suitable action so that traction is regained. Manufacturers often offer this as a separately priced option even though the infrastructure is largely shared with ABS.[citation needed] More sophisticated versions of this can also control throttle levels and brakes simultaneously.

Mercedes-Benz was the first to offer this electronic traction control system in 1985.

[edit] Effectiveness

A 2003 Australian study[3] by Monash University Accident Research Centre found that ABS:

Reduced the risk of multiple vehicle crashes by 18 percent,

Reduced the risk of run-off-road crashes by 35 percent.

On high-traction surfaces such as bitumen, or concrete, many (though not all) ABS-equipped cars are able to attain braking distances better (i.e. shorter) than those that would be easily possible without the benefit of ABS. In real world conditions even an alert, skilled driver without ABS would find it difficult, even through the use of techniques like threshold braking, to match or improve on the performance of a typical driver with a modern ABS-equipped vehicle. ABS reduces chances of crashing, and/or the severity of impact. The recommended technique for non-expert drivers in an ABS-equipped car, in a typical full-braking emergency, is to press the brake pedal as firmly as possible and, where appropriate, to steer around obstructions. In such situations, ABS will significantly reduce the chances of a skid and subsequent loss of control.

In gravel, sand and deep snow, ABS tends to increase braking distances. On these surfaces, locked wheels dig in and stop the vehicle more quickly. ABS prevents this from occurring. Some ABS calibrations reduce this problem by slowing the cycling time, thus letting the wheels repeatedly briefly lock and unlock. The primary benefit of ABS on such surfaces is to increase the ability of the driver to maintain control of the car rather than go into a skid — though loss of control remains more likely on soft surfaces like gravel or slippery surfaces like snow or ice. On a very slippery surface such as sheet ice or gravel, it is possible to lock multiple wheels at once, and this can defeat ABS (which relies on comparing all four wheels, and detecting individual wheels skidding). Availability of ABS relieves most drivers from learning threshold braking.

A June 1999 National Highway Traffic Safety Administration (NHTSA) study found that ABS increased stopping distances on loose gravel by an average of 22 percent.[4]

According to the NHTSA,

"ABS works with your regular braking system by automatically pumping them. In vehicles not equipped with ABS, the driver has to manually pump the brakes to prevent wheel lockup. In vehicles equipped with ABS, your foot should remain firmly planted on the brake pedal, while ABS pumps the brakes for you so you can concentrate on steering to safety."

When activated, some earlier ABS systems caused the brake pedal to pulse noticeably. As most drivers rarely or never brake hard enough to cause brake lock-up, and a significant number rarely bother to read the car's manual,[citation needed] this may not be discovered until an emergency. When drivers do encounter an emergency that causes them to brake hard, and thus encounter this pulsing for the first time, many are believed to reduce pedal pressure, and thus lengthen braking distances, contributing to a higher level of accidents than the superior emergency stopping capabilities of ABS would otherwise promise. Some manufacturers have therefore implemented a brake assist system that determines that the driver is attempting a "panic stop" and the system automatically increases braking force where not enough pressure is applied. Nevertheless, ABS significantly improves safety and control for drivers in most on-road situations.

Design and Selection components.

Given the required reliability, it is illustrative to see the choices made in the design of the ABS system. Proper functioning of the ABS system is considered of the utmost importance, for