ABS (anti lock brakin system ) & ESP (electronic stability programme)

Question

hey guys i want to prepare a presentation on ABS & ESP for my class ... so if some can please give me the detailed description or a good link to browse...

Answer 1

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. 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.

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.

Here is a source to add to the above...

http://www.drivingfast.net/technology/AB...

Answer 2

http://auto.howstuffworks.com/anti-lock-...

http://www.procarcare.com/icarumba/resou...

http://www.aa1car.com/library/abs1.htm

http://www.aa1car.com/library/stability_...

Why not throw in a little on Traction Control while you're there? That'll impress the Teacher.  ;-)

http://www.aa1car.com/library/traction_c...