In Four Wheel Drive (4WD) vehicles, all wheels may slip and the speed reference for the ABS system cannot be measured with wheel speed sensors. Deceleration / acceleration information comes from a longitudinal accelerometer, which is either a stand alone sensor or a PCB mountable component integrated within the ABS controller or in a separate sensor cluster.
The measuring range is typically 1 to 2g. The offset stability better than 100mg over the emperature rangeand life time while the frequency range is typically 50Hz. The sensitive axis must be along the longitudinal axis of the car. VTI has a product range that covers all directions in respect to the sensitive axis compared to the sensor unit and PCB assembly.