Evaluating the Roll Stability of Articulated Vehicles Using a Phase-Plane Analysis Method

An innovative phase-plane analysis method is proposed to assess the roll stability of articulation vehicles. It is well know that the roll instability of articulated vehicles is one of the most serious problems resulting in loss of life and property for drivers. Hence, it is necessary to develop active anti-roll systems to enhance the roll stability of articulated vehicle systems. In order to actuate the active anti-roll control for the articulated vehicle system, effectively threshold values should be determined. Conventionally, vehicle units’ lateral accelerations are used as the roll-over threshold values for active anti-roll control of articulated vehicles. Considering distinguished configurations and unique dynamic features of articulated vehicles, it is questionable whether the lateral-acceleration-based roll-over threshold of single vehicle is effective to evaluate the roll stability of articulated vehicles. In order to address the problem, case studies will be conducted to assess the roll stability of articulated vehicles using the phase-plane method. To this end, this paper will select a car-trailer system, which is represented by a nonlinear vehicle model generated using the CarSim software package. The phase-plane analysis method is used to examine the following relationships between: 1) the leading unit’s roll angle and roll angular velocity (ϕ – dϕ/dt) and 2) the trailing unit’s roll angle and roll angular velocity (ϕ′ – dϕ′/dt). Built upon the conventional phase-plane analysis method for single-unit vehicles, an innovative phase-plane analysis technique is developed in order to effectively assess the roll stability of articulated vehicles. The applicability and effectiveness of the newly developed technique is examined and demonstrated.