Traction control is used on Volkswagen models to maximimize the ability to move a vehicle by limiting wheelspin. There are two distinctly different types of traction control found on Volkswagen models. These are Electronic Differential Lock (EDL), which works at wheels speeds upto 25mph and Anti Slip Regulation (ASR) which works at all vehicle speeds.
EDL aids in maintaining traction by using ABS sensors to detect precisely when individual wheels start to slip. Then it lightly applies brakes at the spinning wheel. This forces the transmission differential to lock and thus try to equalize the torque between the two wheels.
ASR works by using ABS sensors to moniter wheel spin and, as needed, reduces the amount of engine torque delivered to the transmission.
"In Conjunction with ABS, ASR and EDL systems, as well as additional sensors, Electronic Stability Program (ESP) helps the driver maintain their intended course by genertaing corrective forces. ESP is most effective when the driver is taking action during evasive manuevers, like when avaoiding an accident."
ESP has an array of inputs including; Steering Angle, Longitudinal and Transverse Acceleration Rotational Rate sensors. The system actively controls the vehicles brakes and engine to prevent loss of driver control when the vehicle is in danger of skidding.
ESP monitors two parameters: The path the driver wants to go (angle of the steering wheel and wheel speed sensors) and the vehicles direction of travel (other wheel sensors provide this information).
As an example, if a vehicle threatens to understeer, ESP responds by selectively activating the rear brake on the inside corner, and intervening in the engine and transmission management systems, to prevent the vehicle from over shooting the corner.
