车辆行驶的虚坡模型

VIRTUAL SLOP MODEL PROPOSED FOR THE SIMULATION OF RUNNING PROCESSES OF VEHICLES

传统方法在模拟车辆行驶时尚存在不足。对于元胞自动机模型,当各车辆的最大速度不一致且车辆数目较多时,会产生计算困难。文中提出一种对车辆行驶进行模拟的虚坡模型,它假想每车尾部有一类似于动物负责运动协调的尾巴的虚坡,其形状如中间受集中载荷的固支梁挠度曲线的半支所示。各车的速度由其触及到的前方车辆的虚坡宽度及道路宽度等局部环境计算,并用固支梁挠度曲线对其进行必要的平滑。它无需将道路划分为一系列的单元格,同时又是一种分析形式,而非统计形式的模型。该模型被用于模拟具有不同最大速度的车辆行驶过程。计算结果表明该模型能在一定程度上适应车辆行驶过程复杂多变的特点,能对跟车和超车过程统一地进行模拟,且可对车辆数较多的交通流问题进行模拟。司机行为可以体现为有关固支梁的强度。

Traditional methods have their shortcomings in simulating running processes of vehicles. Cellular automaton models have calculation difficulties when the maximum speeds of the vehicles are different from each other or the number of the vehicles is very large. A virtual/dash slop model was proposed for the simulation of the running processes of vehicles. It supposed that behind each vehicle there was a virtual or imaginary attaching slop taking the shape of the half of the deflection curve of a built-in beam having a vertical load on its central point. Liking a tail of an animal, a virtual slop was introduced to coordinate the motion of the vehicles, The speed of each vehicle was calculated according to the widths of the virtual slops it touched, the width of the road and other local environment conditions. The deflection curve of a built-in beam was adopted to make the speed continuous if necessary. The road didn＇t have to be separated to a series of grids in the proposed model. It＇ s an analytical model rather than a statistical model. It has been used for the simulation of running processes of vehicles of different maximum speeds. The simulation results shows that the virtual slop model fits the complicate dynamic characteristics of the running processes of vehicles to some extent. Another revealed characteristic of the model is that it simulates car-following processes and overtaking processes in a unified way. And it could simulate traffic flow problems in which many vehicles exist. The behavior of a driver could be expressed as the strengths of the related built-in beams.