1 Stability Analysis and Rollover Scenario Prediction For Tractor Semi-Trailer Mohamed Bouteldja12, Nacer K. M’Sirdi1, S´ebastien Glaser 2, VictorDolcemascolo2 1 Laboratoire de Robotique de Versailles, CNRS/FRE2659 10-12 avenue de l’Europe, 78140 VELIZY, FRANCE 2Laboratoire Central des Ponts et Chauss´ees 58 Bd Lef`evre, 75014 PARIS, FRANCE Abstract—In this paper, we present a stability analysis of heavy vehicle through variation of the parameters influencing the rollover. A 5-DOF nonlinear dynamic simulation model for tractor semi-trailers is proposed. The proposed model is used to validate the prediction of rollover. Threshold accelerations deduced using quasistatic analysis. The predicted threshold accelerations are compared with simulation threshold accelerations. Index Terms—Modelling, Heavy Vehicle, Rollover, Prediction, Stability. I. Introduction The tractor semitrailer represents a population of risky vehicles, both for themselves as well as other road users. Moreover, for a limited capacity of the infrastructure, the number and density of heavy vehicles grow faster than those of cars. Accidents involving heavy lorries have serious consequences for road users, and incidents induce major congestions or damage to the environment or the infrastructure at disproportionate economic costs. For instance, the risk of having a dead people is 2.4 higher when lorries are involved in accident [1]. To reduce the number of accidents and to improve safety, several solutions have been studied in some programs dealing with the idea and activity of Intelligent Transportation Systems (US NAHSC program, California PATH Program, Japan’s AHSRA, European programs: ADASE, REPONSE and CHAUFEUR-driven, French PREDIT and ARCOS programs, etc.) [2]. Some orientations of these programs may consist of driver assistance, active safety systems (lateral control) and passive safety systems (detection and warning message under hazardous conditions). Some commercial systems installed in the infrastructure before a dangerous cornering, are able to measure the truck speed. In case of overspeed leading to a rollover in the cornering, a warning is sent to the driver in order to incite him to decrease its speed. Other systems are installed aboard the truck. They can, using informative (passive) nature as measuring lateral acceleration, issue a warning signal to the driver when it goes beyond some risky thresholds. In case of active systems, the concept is to minimize the lateral acceleration by braking action, steering action, suspension action or anti-roll action or a combination of all. Naleck and al [3] have defined, for the detection of rollover, a measurement based on the energy reserve until to have a rollover situation (Rollover Prevention Energy Reserve). At the same time, Dunwoody simulated the steady state cornering performance of a tractor semitrailer fitted with an active roll control system. The control system required the measurement of the trailer lateral acceleration and the relative roll angle between the tractor and the trailer. The study stated that such a system could raise the static rollover threshold by 20-30% [4]. Dahlberg gave the definition of the remaining energy margin that lead to rollover [5]. This margin is the di erence between the critical potential energy and the sum of the potential and kinetic rollover energy. Chen et al. defined a short predictive criterion called TTR (Time to Rollover) which takes into account the dynamic state evolution of the vehicle [6]. Ackermann et al. [7], [8] have studied the influence of the inertia force and the centre of gravity height on the roll dynamics of the vehicle heavy. He defined the load transfer ratio (LTR) for an axle as the ratio of the di erence between right and left impact force by the sum of right and left impact force. If LTR is greater than 0.9, rollover risk is high. He showed that LTR is approximately a function of the lateral acceleration (easy to measure) and the center of gravity height (for which no sensor is available) Lin et al. then investigated roll control system design using an optimal state feedback technique and a steering input power spectrum based on road alignement data and pseudo-random lane changes [9]. The system performance was marginally superior to that of the lateral acceleration feedback controller. This work is developed as part of the ”safety of heavy vehicle” subject of ARCOS 2004 program. The objectives are to develop a strategy to detect critical situations and trigger a warning signal under dangerous conditions such as unstable yaw or rollover, and allow real-time detection .....