Determination of vehicle reference speed for ABS system

In a practical ABS system the vehicle speed can not be determined directly without a correlative sensor equipped. So it is very important to calculate vehicle reference speed exactly in ABS. In this paper, the methods of determination of vehicle reference speed were analyzed, such as the max wheel speed method, the slope method and the adaptive slope method. The merits and defects of each method, as well as their applying conditions, were stated. By the road test of a car modeled VW Jetta GTX, the adaptive slop method showed a better performance.