Enhanced Lateral and Roll Stability Study for a Two-Axle Bus via Hydraulically Interconnected Suspension Tuning

The suspension system has been shown to have significant effects on vehicle performance, including handling, ride, component durability, and even energy efficiency during the design process. In this study, a new roll-plane hydraulically interconnected suspension (HIS) system is proposed to enhance both roll and lateral dynamics of a two-axle bus. The roll-plane stability analysis for the HIS system has been intensively explored in a number of studies, while only few efforts have been made for suspension tuning, especially considering lateral plane stability. This article aims to explore the integrated lateral and roll dynamics by suspension tuning of a two-axle bus equipped with HIS system. A ten-degree-of-freedom (DOF) lumped-mass vehicle model is integrated with either transient mechanical-hydraulic model for HIS or the traditional suspension components, namely, shock absorber and anti-roll bar (ARB). Three novel parameters of HIS system are proposed as the suspension tuning rules which are defined as total roll stiffness (TRS), roll stiffness distribution ratio (RSDR), and roll-plane damping (RPD). Using Fishhook maneuver, dynamic responses of both vehicle models are obtained when they have different combinations of the suspension parameters mentioned above. The vehicle responses are evaluated by the vehicle performance terms: lateral acceleration, roll angle, yaw rate, vehicle trajectory, sideslip angle, lateral displacement, and lateral and longitudinal velocity of the vehicle. To validate the simulation work, using double-lane-change maneuver, the field test of the tested bus equipped with two kinds of suspension is performed. Based on both simulation and measurement, some basic suspension tuning rules for buses are proposed which is beneficial for practical design of HIS system.