On the basis of the steering angle, the system recognizes the desired direction of travel. Speed sensors on each wheel measure wheel speed. At the same time, yaw-rate sensors measure vehicle rotation around its vertical axis, as well as lateral acceleration. From this data, the control unit calculates the actual movement of the vehicle, comparing it 25 times per second with the desired direction of travel. If the values do not correspond, the system reacts in an instant, without any action on the part of the driver. It reduces engine power in order to restore vehicle stability. If that is not sufficient, then it additionally brakes individual wheels. The resulting rotary movement of the vehicle counteracts the skidding movement – within the limits of the laws of physics, the vehicle remains safely on the desired course.
The ESP® system offers value-added functions that increases comfort and safety. As for example, hill hold control assists the driver when starting off on inclines by independently applying the brakes for around two seconds after the driver has released the brake pedal. The system can also protect vehicles with a high center of gravity from the risk of rolling over.
ESP® value-added functions