Analysis of Vehicle Driving Stability based on Longitudinal-lateral and Vertical Unified Dynamics Model

Abstract

Vehicle driving stability is the basis of chassis integrated control and automatic driving. In this paper, we construct an 18 degrees of freedom (DOF) unified dynamics model of vehicle chassis. The unified dynamics model includes three subsystems: steering subsystem, brake subsystem and suspension subsystem, in which the coupling relationships among the three subsystems above are considered. Combined with phase plane analysis method, choosing the sideslip angle of vehicle center of gravity (c.g.) and yaw rate as the evaluation indexes, the influences of front wheel steering angle, road adhesion coefficient, braking mode of front and rear wheels and initial speed on vehicle driving stability are analyzed. In particular, phase plane and bifurcation analysis methods are used to study the influence of uneven road on vehicle driving stability, which has not been reported yet. The main contribution of this paper is to make a comprehensive analysis of the vehicle driving stability by the 18-DOF model above. Through the comprehensive simulation analysis of the above factors by Matlab/Simulink, we can fully grasp the driving stability law of the vehicle under different working conditions. With the above analysis method, the stability of various control systems designed for vehicle chassis can be evaluated more objectively.