公路空间几何特性对汽车运动影响

从三维的角度采用曲率、挠率代替传统平、纵线形设计参数对公路中心线的空间几何特性进行描述,并在Frenet标架的基础上,将汽车视为刚体,从微观角度建立了以三维线形指标曲率、挠率为控制量的汽车空间运动模型.结合已有设计资料,对公路线形的空间几何特性对汽车运动的影响进行了详细分析.研究发现曲率的设置对汽车行驶起主导作用,挠率的影响相对较小;传统路线设计方法忽略了平、纵线形的耦合使得组合线形的曲率、挠率的连续性存在不同程度的衰减,直接影响到行车运动状态的平稳变化和行车舒适性水平.

Influence of Spatial Geometric Properties of Highway Alignments on Vehicle Kinematics

Firstly, curvature and torsion instead of traditional two dimensional (2 D) horizontal and vertical indexes were used to describe the spatial geometric properties of highway alignment according to the curve theory of differential geometry. Then the vehicle was treated as a rigid body and a new motion model was established with the curvature and torsion as the control variables base on the Frenet Frame. Finally, an example was analyzed to demonstrate the influence of spatial geometric properties of an existing highway on vehicle kinematics. It is found that the setting of curvature plays a leading role in the spatial motion, while the torsion affects the motion less. The coupling effects of horizontal and vertical alignments were ignored during traditional design process, which led to the continuity degradation of curvature and torsion, and directly affected the smooth variation of vehicle motion and driving comfort.