Abstract

The accurate prediction of an impending rollover threat of a heavy vehicle forms the essential basis for developing a rollover prevention system. The vehicle roll stability and the rollover predictors are most significantly related to the center of gravity height of the trailer sprung mass, which tends to vary considerably. The developments in the rollover warning devices have been mostly limited due to extreme complexities associated with the onsite measurement of the center of gravity height of an arbitrarily loaded vehicle. In this study, the system identification techniques are applied to obtain an estimate of the c.g. (Center of Gravity) height on the basis of the measured response under a controlled directional maneuver. A simulation model of a five-axle tractor-semitrailer is analyzed in the TruckSim environment to identify the desirable response measure, which is most sensitive to variation in the c.g. height, and the test maneuver for deriving the desired response. A 10 D.O.F. (degree-of-freedom) analytical model of the vehicle is developed and linearized to derive the analytical transfer function relating the steer angle to the desired semitrailer sprung mass roll angle response. A model reduction technique is further applied to obtain a reduced-order analytical transfer function to facilitate its implementation.