Oscillatory Yaw Motion Control for Hydraulic Power Steering Articulated Vehicles Considering the Influence of Varying Bulk Modulus

In this investigation, a detailed hydraulic steering system of articulated steer vehicles (ASVs) and a 12-DOF ASV model are developed for vehicle dynamics performance research. The real-time changing characteristic of oil bulk modulus is considered. Field test and multibody dynamics model by Adams/View software are compared with the established mathematical model, respectively, to verify the correctness of the model at low speed and high speed. The snaking and oscillatory area is confirmed to reveal the influence of varying bulk modulus on the stability of ASV. To improve the stability of ASV, the direct yaw moment control system and driving force distribution system are designed with the application of the optimal control theory. The upper level controller calculates the expected yaw moment by feedforward and feedback compensatory strategies. Different from zero-sideslip control in most studies, an Ackermann-based sideslip angle is used for feedforward compensatory gain derivation and reference model design. The lower level controller distributes the driving force for each wheel aiming at the optimal utilization rate of tires. High-speed weave test by sinusoidally steering for loaded ASV is simulated to verify the effectiveness of the control algorithms.