braking and traction control in automobile pdf

Braking And Traction Control In Automobile Pdf

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Fortunately, car companies long ago realised that most humans were far too flawed, flakey and uncoordinated to be trusted with this kind of responsibility, so they set out to develop software to do it for us. Since the advent of early, basic and, frankly, slightly annoying traction-control systems - which used to cut the power on you at the slightest suggestion of wheel spin - cars have become cunningly adept at keeping us on the road. So much so that grateful governments have made it illegal to sell new cars without stability-control systems fitted as standard. Australia made ESP Electronic Stability Program compulsory for all passenger cars in , and on November 1 this year the law will also apply to all new-model light commercial vehicles.

Stability control and traction control - do you need them?

An anti-lock braking system ABS is a safety anti- skid braking system used on aircraft and on land vehicles , such as cars , motorcycles , trucks , and buses. ABS is an automated system that uses the principles of threshold braking and cadence braking , techniques which were once practiced by skillful drivers before ABS was widespread.

ABS operates at a much faster rate and more effectively than most drivers could manage. Although ABS generally offers improved vehicle control and decreases stopping distances on dry and some slippery surfaces, on loose gravel or snow-covered surfaces ABS may significantly increase braking distance , while still improving steering control. Modern versions may not only prevent wheel lock under braking, but may also alter the front-to-rear brake bias. This latter function, depending on its specific capabilities and implementation, is known variously as electronic brakeforce distribution , traction control system , emergency brake assist , or electronic stability control ESC.

The concept for ABS predates the modern systems that were introduced in the s. In , for example, J. In the French automobile and aircraft pioneer Gabriel Voisin experimented with systems that modulated the hydraulic braking pressure on his aircraft brakes to reduce the risk of tire slippage, as threshold braking on aircraft is nearly impossible.

These systems used a flywheel and valve attached to a hydraulic line that feeds the brake cylinders. The flywheel is attached to a drum that runs at the same speed as the wheel. In normal braking, the drum and flywheel should spin at the same speed. However, when a wheel slows down, then the drum would do the same, leaving the flywheel spinning at a faster rate.

This causes the valve to open, allowing a small amount of brake fluid to bypass the master cylinder into a local reservoir, lowering the pressure on the cylinder and releasing the brakes. The use of the drum and flywheel meant the valve only opened when the wheel was turning. An additional benefit was the elimination of burned or burst tires. The first proper recognition of the ABS system came later with the German engineer Karl Waessel, whose system for modulating braking power was officially patented in Wessel, however, never developed a working product and neither did Robert Bosch who produced a similar patent eight years later.

Enfield's technical director at the time, Tony Wilson-Jones, saw little future in the system, however, and it was not put into production by the company. A fully-mechanical system saw limited automobile use in the s 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 unreliable.

The first fully-electronic anti-lock braking system was developed in the lates for the Concorde aircraft. Chrysler , together with the Bendix Corporation , introduced a computerized, three-channel, four-sensor all-wheel [10] ABS called "Sure Brake" for its Imperial. In , General Motors introduced the "Trackmaster" rear-wheel only [14] ABS as an option on their rear-wheel drive Cadillac models [15] [16] and the Oldsmobile Toronado.

Toyota introduced electronically controlled anti-skid brakes on Toyota Crown. Such cars were very rare however and very few survive today. The Norwegian general agent also included a sunroof and other options to be standard equipment in Norway, adding more luxury to the Honda brand.

However, the Norwegian tax system made the well-equipped car very expensive, and the sales suffered from high costs.

From the ALB-system, as well as the other optional features from Honda, was no longer a standard feature in Norway. In the Ford Scorpio was introduced to the European market with a Teves electronic system throughout the range as standard.

For this the model was awarded the coveted European Car of the Year Award in , with very favorable praise from motoring journalists. After this success, Ford began research into Anti-Lock systems for the rest of their range, which encouraged other manufacturers to follow suit.

In , Lincoln became one of the first automobile companies to provide standard four-wheel anti-lock brakes and dual-airbags on all of their vehicles. Typically ABS includes a central electronic control unit ECU , four wheel speed sensors , and at least two hydraulic valves within the brake hydraulics.

The ECU constantly monitors the rotational speed of each wheel; if it detects the wheel rotating significantly slower than the speed of the vehicle, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel; the wheel then turns faster.

Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel.

This process is repeated continuously and can be detected by the driver via brake pedal pulsation. Some anti-lock systems can apply or release braking pressure 15 times per second. The ECU is programmed to disregard differences in wheel rotative speed below a critical threshold because when the car is turning, the two wheels towards the center of the curve turn slower than the outer two. For this same reason, a differential is used in virtually all roadgoing vehicles.

If a fault develops in any part of the ABS, a warning light will usually be illuminated on the vehicle instrument panel, and the ABS will be disabled until the fault is rectified.

Modern ABS applies individual brake pressure to all four wheels through a control system of hub-mounted sensors and a dedicated micro-controller. ABS is offered or comes standard on most road vehicles produced today and is the foundation for electronic stability control systems, which are rapidly increasing in popularity due to the vast reduction in the price of vehicle electronics over the years.

Modern electronic stability control 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.

ABS equipment may also be used to implement a traction control system TCS on the 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. More sophisticated versions of this can also control throttle levels and brakes simultaneously. The speed sensors of ABS are sometimes used in indirect tire pressure monitoring system TPMS , which can detect under-inflation of the tire s by the difference in the rotational speed of wheels.

There are four main components of ABS: wheel speed sensors , valves , a pump , and a controller. The majority of problems with the valve system occur due to clogged valves. When a valve is clogged it is unable to open, close, or change position. An inoperable valve will prevent the system from modulating the valves and controlling pressure supplied to the brakes. There are many different variations and control algorithms for use in ABS. One of the simpler systems works as follows: [26].

Anti-lock braking systems use different schemes depending on the type of brakes in use. They can be differentiated by the number of channels: that is, how many valves that are individually controlled—and the number of speed sensors.

On high-traction surfaces such as bitumen , or concrete , many though not all ABS-equipped cars are able to attain braking distances better i. In real-world conditions, even an alert and experienced driver without ABS would find it difficult to match or improve on the performance of a typical driver with a modern ABS-equipped vehicle. 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. Some vehicle manufacturers provide an "off-road" button to turn the ABS function off. 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 the loss of control remains more likely on soft surfaces such as gravel or on slippery surfaces such as 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. The availability of ABS relieves most drivers from learning threshold braking. 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 ABSes caused the brake pedal to pulse noticeably. As most drivers rarely or do not brake hard enough to cause brake lock-up, and drivers typically do not read the vehicle's owner's manual, this may not be noticeable until an emergency. Some manufacturers have therefore implemented a brake assist system that determines that the driver is attempting a "panic stop" by detecting that the brake pedal was depressed very quickly, unlike a normal stop where the pedal pressure would usually be gradually increased.

Hard or panic braking on bumpy surfaces, because of the bumps causing the speed of the wheel s to become erratic may also trigger the ABS, sometimes causing the system to enter its ice mode, where the system severely limits maximum available braking power. Nevertheless, ABS significantly improves safety and control for drivers in most on-road situations. Anti-lock brakes are the subject of some experiments centred around risk compensation theory, which asserts that drivers adapt to the safety benefit of ABS by driving more aggressively.

In a Munich study, half a fleet of taxicabs was equipped with anti-lock brakes, while the other half had conventional brake systems. The crash rate was substantially the same for both types of cab, and Wilde concludes this was due to drivers of ABS-equipped cabs taking more risks, assuming that ABS would take care of them, while the non-ABS drivers drove more carefully since ABS would not be there to help in case of a dangerous situation.

On a motorcycle, an anti-lock brake system prevents the wheels of a powered two wheeler from locking during braking situations. Based on information from wheel speed sensors the ABS unit adjusts the pressure of the brake fluid in order to keep traction during deceleration to avoid accidents.

Motorcycle ABS helps the rider to maintain stability during braking and to decrease the stopping distance. It provides traction even on low friction surfaces. While older ABS models are derived from cars, recent ABS is the result of research, oriented on the specifics of motorcycles in case of size, weight, and functionality.

National and international organizations evaluate Motorcycle ABS as an important factor to increase safety and reduce motorcycle accident numbers. Consumer Reports said in that "ABS is commonly offered on large, expensive models, but it has been spreading to several entry-level sportbikes and midsized bikes". It was developed together with FAG Kugelfischer and regulated the pressure in the braking circuits via a plunger piston.

It has been developed in cooperation with BMW and weighed 2. The current generation presented by Bosch in weighs 0. Wheel speed sensors mounted on the front and rear wheel constantly measures the rotational speed of each wheel and delivers this information to an Electronic Control Unit ECU.

The ECU detects on the one hand if the deceleration of one wheel exceeds a fixed threshold and on the other hand whether the brake slip, calculated based on information of both wheels, rises above a certain percentage and enters an unstable zone. These are indicators for a high possibility of a locking wheel. To countermeasure these irregularities the ECU signals the hydraulic unit to hold or to release pressure. After signals show the return to the stable zone, the pressure is increased again.

Past models used a piston for the control of the fluid pressure. Most recent models regulate the pressure by rapidly opening and closing solenoid valves. While the basic principle and architecture has been carried over from passenger car ABS, typical motorcycle characteristics have to be considered during the development and application processes.

One characteristic is the change of the dynamic wheel load during braking.

Vehicle Traction Control And its Applications

An anti-lock braking system ABS is a safety anti- skid braking system used on aircraft and on land vehicles , such as cars , motorcycles , trucks , and buses. ABS is an automated system that uses the principles of threshold braking and cadence braking , techniques which were once practiced by skillful drivers before ABS was widespread. ABS operates at a much faster rate and more effectively than most drivers could manage. Although ABS generally offers improved vehicle control and decreases stopping distances on dry and some slippery surfaces, on loose gravel or snow-covered surfaces ABS may significantly increase braking distance , while still improving steering control. Modern versions may not only prevent wheel lock under braking, but may also alter the front-to-rear brake bias. This latter function, depending on its specific capabilities and implementation, is known variously as electronic brakeforce distribution , traction control system , emergency brake assist , or electronic stability control ESC.

These four features are often associated with safety during driving. But do you know the real meaning of these terms? As the name implies, the ABS prevents the car wheels from locking when the car brakes suddenly in certain situations. Simply speaking, a car that has been equipped with the ABS can still avoid when it is braked suddenly. Without the ABS, however, the car wheels will be locked upon a sudden brake and thus collisions are inevitable. The ABS consists of three main components, namely the speed sensor in each wheel, a valve of the hydraulic that leads to each brake pump to return the pressure of the hydraulic brake controlled by a computer, and also a control module.


In fact, ABS setups are the foundation upon which traction control systems are built. ABS helps to prevent wheel slip when a vehicle is braking in slippery.


Anti-lock braking system

Widespread usage of emission free public transport is the preferred strategy in many cities to reduce a congestion and pollution from the road traffic. The trolleybus is a kind of urban public transport, i. The operation control of service brake system and secondary brake system the braking torque of traction electric motor is realized with help of one pedal in the trolleybus.

Traction control system (TCS)

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Traction control system (TCS)

Widespread usage of emission free public transport is the preferred strategy in many cities to reduce a congestion and pollution from the road traffic. The trolleybus is a kind of urban public transport, i. The operation control of service brake system and secondary brake system the braking torque of traction electric motor is realized with help of one pedal in the trolleybus.

Sivasubramanian, Mr. Ahamath Basha, Mr. Ajai, Mr. Dharsan Chandra Sekar. Abstract:- The benefits of Vehicle Electronic Stability Control ESC are well understood with regard to assisting drivers to maintain vehicle control during extreme handling maneuvers or when extreme road conditions are encountered. A certain vehicle dynamics model was developed with two way braking system. One is normal mode in which it acts as a normal brake when driver applies it.

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Modern vehicles feature electronic traction control, which relied on the use of sensors embedded into the Anti-lock. Braking system (ABS).


Fortunately, car companies long ago realised that most humans were far too flawed, flakey and uncoordinated to be trusted with this kind of responsibility, so they set out to develop software to do it for us. Since the advent of early, basic and, frankly, slightly annoying traction-control systems - which used to cut the power on you at the slightest suggestion of wheel spin - cars have become cunningly adept at keeping us on the road. So much so that grateful governments have made it illegal to sell new cars without stability-control systems fitted as standard.

В этом случае сотрудники лаборатории систем безопасности тщательно изучали их вручную и, убедившись в их чистоте, запускали в ТРАНСТЕКСТ, минуя фильтры программы Сквозь строй. Компьютерные вирусы столь же разнообразны, как и те, что поражают человека. Подобно своим природным аналогам они преследуют одну цель - внедриться в организм и начать размножаться. В данном случае организмом является ТРАНСТЕКСТ.

 Тихо, - потребовал Фонтейн и повернулся к Сьюзан.  - Мисс Флетчер, вы проделали уже немалую часть пути. Постарайтесь пройти по нему до конца.

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