Detection of critical situations for vehicle longitudinal dynamics

The objective of this paper is to design a new integrated methodology for the detection of a critical situation in vehicle longitudinal dynamics. In classical modern vehicle, the ABS - anti-lock braking system - (during bracking) and anti-skid (during accelerations) modules are acting separately. This paper presents an innovative methodology for the detection of longitudinal critical situations that can be used as an information for both ABS and anti-skid programs. The approach is based on the non-linear tire modeling that consists of three operating zones : normal zone, critical and skidding. The normal zone can be approximated by a linear representation of the tire force while this modeling is no longer acceptable in the other regions. Based on this statement, a robust fault detection methodology allows to detect the non-linear characteristics of the tire force representing the critical situation. Applicative results have been implemented on a 1/5th scale vehicle developed in the framework of the French national ANR INOVE project.