DETECTION OF CRITICAL SITUATIONS FOR
LATERAL VEHICLE CONTROL
N. Zbiri *,** A. Rabhi ** N. K. M’Sirdi **
* Laboratoire des Systèmes Complexes 40 rue du Pelvoux
CE 1455 Courcournnes 91020 Evry Cedex
** Laboratoire de Robotique de Versailles LRV 10-12
Avenue de l’Europe 78140, Vélizy, France
zbiri@lrv.uvsq.fr msirdi@lrv.uvsq.fr
Abstract: In this paper, we propose and develop a "look-ahead" system for
detection of over steering or under steering situations. The approach is based
on the combination of an observer and a vision system which estimates the road
curvature and a change detection procedure. We use an average sequential test
to detect the abnormal situations. Simulation results shows the e?ciency of the
method.
Keywords: On line observers and estimation, faults and changes detection,
sequential test, vehicle lateral control, assistance, driving.
1. INTRODUCTION
Recently, safety and drivability of vehicles is of
increasing interest. Today’s advanced driver assistance
systems are widely used in modern vehicles.
Their objective is to assist the driver by
preventing any unstable or unpredictable vehicle
behavior. One critical situation which has received
a particular attention is the deviation of the vehicle
from its trajectory. Di?erent reference systems
have been examined for detecting the lateral vehicle
motion. Most existing approaches to automatic
steering can be classified into “look-ahead” [1 - 3], and “look-down” [4] systems according to the
point of measurement of lateral displacement. The
advantage of “look-ahead” systems is their ability
to replicate human driving by measuring lateral
displacement.
The objective of this work is to design a “lookahead”
system detection for over steering or under
steering situations. The methodology developed is
based on vehicle state and trajectory estimation.
The detection of the deviation of the vehicle from
its trajectory is then obtained using the Wald
Sequential Average Test (WSA) [5].
2. MODELLING
2.1 Lateral model
The dynamics of a single track vehicle can be
described by a detailed 16-DOF [6] non linear
model. In other systems, it is possible to decouple
the longitudinal and lateral dynamics [7].
The kinematical behaviour of the vehicle can be
in this application approximated by the bicycle
model, see figure 1.
In this paper we use the following notation :
m total mass of the vehicle
Jzz the vehicle inertia around gravity center (CG)
v velocity of the vehicle at (CG)
vy lateral velocity
lr , lf distance of front and rear axles from (CG)
Fxy, Fyf are longitudinal and
lateral forces

.....