武汉市城市道路机动车车道宽度研究

横断面宽度是道路全局性参数,机动车道是横断面最主要的组成部分。该文对武汉市城市道路机动车道宽度进行了研究,选择合理的机动车车道宽度,具有十分重要的经济和社会意义。     

城市一幅路道路的慢行系统改造方案研究

该文以武汉市香港北路为例,分析总结了一幅路道路的慢行系统在使用中存在的问题及其产生的原因,通过两个具体改造方案探讨了武汉市乃至我国其他城市改造一幅路道路慢行系统的可行方法与措施,并对城市道路慢行系统及非机动车道改造提出了相关建议。     

基于双曲函数的车辆减速策略及安全跟驰车距的计算

车辆减速策略与跟驰车距具有相互制约的关系.分析了车辆减速运动规律,提出反映人们期望和行为特点的基于双曲函数的车辆减速策略,进而建立计算安全跟驰车距的数学模型,并按照国际载运工具和我国上海磁浮列车的运行舒适性评价标准,对200 km/h跟驰速度条件下安全车距的计算式进行了仿真试验与数值分析,验证了相关数学模型与计算方法的有效性.     

北京市朝阳路可变车道交通组织研究

阐述了可变车道交通组织的相关概念及应用情况。通过对北京市朝阳路的道路、交通流量等情况进行分析,运用实地调查数据,论证了设置可变车道的可行性,并提出了可变车道的实施方案及相关问题的解决策略,以达到缓解早、晚高峰时段朝阳路的交通拥堵状况的目的。     

基于饱和度的车道数量确定方法

文章从理论上推导了交通需求与道路宽度、有效通行时间比的相对关系，进而推导出一个流向上的车道数量的计算公式，并针对典型的十字交叉口和路段情况，详细讨论了交叉口进出口道和路段上车道数量计算公式。最后，对一个算例进行了验证和总结。     

ETC系统缴费方式随机选择模型

针对组合式收费系统中驾驶员缴费方式的随机选择行为,以排队论与非集计理论为基础,建立电子收费(Electronic Toll Collection,ETC)系统缴费方式随机选择模型及均衡状态求解算法。通过均衡分析与灵敏度分析探讨了ETC技术的采用对道路使用者的技术选择与车道选择行为所产生的影响,所得结果可为ETC系统的规划和管理提供帮助。     

商用车电液复合转向系统的车道保持策略

为了提高商用车的行驶安全性,避免因驾驶人的分心驾驶出现车辆偏离车道的问题,提出一种基于电液复合转向系统的商用车车道保持策略;在建立电液复合转向系统模型、二自由度车辆模型、预瞄驾驶人模型的基础上,设计基于驾驶人在环的MPC和ADRC串级的车道保持控制策略。首先,采用MPC算法将车辆横向位置控制的最优问题转化为二次规划求得目标前轮转角;然后,考虑电液复合转向系统的不确定和干扰问题,利用ADRC算法对目标转向盘转角和实际驾驶人的转向盘转角差值以转矩信号的形式进行补偿。同时研究车道保持系统对驾驶人的干预问题,引入干预系数的概念,采用模糊控制的方法,将驾驶人手力和车辆的运动状态作为输入变量,干预系数作为输出变量,保证整车行驶安全性的前提下减小车道保持辅助系统对驾驶人的干预。最后,通过MATLAB/Simulink仿真和硬件在环试验对所设计的控制策略进行验证。研究结果表明：所设计的基于商用车电液复合转向系统的车道保持策略能够及时地纠正因驾驶人的分心驾驶而导致车辆偏离所在行驶车道的行为,特别是在弯道处出现驾驶人转向不足或过度转向的情况时,能够将车辆维持在车道线之内,保证车辆的行驶安全性,同时由于干预系数的设计,使得驾驶人也有良好的人机交互体验感。     

基于绿色交通理念的拉萨交通优化研究——以朵森格路中段为例

绿色交通强调交通与环境的和谐发展,强调社会的可持续发展。拉萨处于高原地区,生态环境脆弱,随着拉萨的不断发展,交通问题和其引起的环境问题日益凸显,对拉萨交通进行符合绿色交通理念的优化有着重要的意义。基于绿色交通的理念,对拉萨的交通特点进行概述,对朵森格路中段的交通状况进行详细分析,并对其提出规整慢行通道和以公共交通为主地位的潮汐车道等优化策略,为拉萨交通的绿色规划和优化提供参考。     

Implications of path tolerance and path characteristics on critical vehicle manoeuvres

Path planning and path following are core components in safe autonomous driving. Typically, a path planner provides a path with some tolerance on how tightly the path should be followed. Based on that, and other path characteristics, for example, sharpness of curves, a speed profile needs to be assigned so that the vehicle can stay within the given tolerance without going unnecessarily slow. Here, such trajectory planning is based on optimal control formulations where critical cases arise as on-the-limit solutions. The study focuses on heavy commercial vehicles, causing rollover to be of a major concern, due to the relatively high centre of gravity. Several results are obtained on required model complexity depending on path characteristics, for example, quantification of required path tolerance for a simple model to be sufficient, quantification of when yaw inertia needs to be considered in more detail, and how the curvature rate of change interplays with available friction. Overall, in situations where the vehicle is subject to a wide range of driving conditions, from good transport roads to more tricky avoidance manoeuvres, the requirements on the path following will vary. For this, the provided results form a basis for real-time path following.     

A cellular automata (CA) model for motorized vehicle flows influenced by bicycles along the roadside

On many urban low‐grade or branch roads, especially in medium or small cities in China, bicyclists and motorists commonly share the non‐barrier road surface. Because bicycles are unpredictable and unstable when moving, motorized vehicles must reduce their speed to safely approach and overtake them. In this study, the gradual deceleration process a motorized vehicle undergoes before it passes a bicycle was analyzed. The motorist was assumed to prefer a comfortable deceleration and to select a higher deceleration rate only when the distance to the bicycle was insufficient to reduce the car's speed to the expected value at a comfortable deceleration rate. Cellular automata (CA) simulations were used to reveal the flow characteristics of motorized vehicles reacting to bicycles traveling along the roadside, and the results show that for the general velocities of motorized vehicles and bicycles traveling on urban branch roads, the road capacity for motorized vehicles is not related to the number of bicycles present. However, the average travel time of motorized vehicles is significantly affected by the presence of bicycles when the number of motorized vehicles on the road is small. In addition, motorized vehicles' average travel time is more influenced by disturbances in the flow of motorized vehicles than by bicycles when the number of motorized vehicles on the road is large. Field observations and surveys were used to validate the traffic behaviors and simulation results. Copyright © 2016 John Wiley & Sons, Ltd.