智能网联汽车协同生态驾驶策略综述

为了跟踪近年来智能网联汽车(CAV)协同生态驾驶策略的研究进展, 分析了车辆、驾驶行为、交通网络和社会这4类因素对CAV能耗的影响程度, 以车辆、基础设施和旅行者为对象对目前CAV生态研究进行分类, 重点分析了信号交叉口生态驶入与离开、生态协同自适应巡航控制、匝道合流区生态协同驾驶、生态协同换道轨迹规划和生态路由5种典型车辆协同生态驾驶应用场景的研究现状。分析结果表明: 相比人类驾驶方式, 在任何交通流量CAV 100%渗透率的条件下和低交通流量CAV部分渗透率的条件下, CAV油耗节省效果显著, 最高可达63%, 而具有部分智能化和网联化等级的CAV油耗可至少节省7%;现有研究较少考虑人机共驾情况下, 驾驶人反应延迟和自动控制器传输延迟导致的轨迹跟踪偏离; 现有研究将车车通信/车路通信假定为理想数据交互过程, 未考虑通信拓扑、传输时延、通信失效与基站切换等因素对CAV生态协同驾驶策略的影响; 现有研究较少探讨多车道、交叉口转向-直行共用车道和U型车道等交通场景, 以及不同智能网联等级CAV与人类驾驶汽车、行人、自行车等共存的混合交通条件下的生态驾驶策略; 受限于自动驾驶技术和基础设施尚未成熟和完善, 真实交通场景下的测试验证工作尚未开展; 车辆控制、车车通信、多车协同、混合交通流场景、半实物仿真测试和真实交通场景测试等方面将是CAV协同生态驾驶策略的进一步发展方向。     

基于巡航控制的公交运输系统元胞自动机模型

针对公共交通系统,基于巡航控制的思想,本文提出一个新的可变跃迁概率元胞自动机（CA）模型. 模型中假设公交车辆并非唯一追求以最大速度行驶,而是根据期望车头距动态调整车辆向前移动的速度,实现了公交线路上车辆之间的相互合作以及协调行驶行为. 通过数值模拟实验表明,该模型可以再现公交集簇前行的现象,引入新的控制策略后,模型改善了车辆在公交线路上的时空分布,疏散了公交车辆集簇行驶的状况,进而在很大程度上提高了公交系统内车辆运行的平均速度并且降低了平均等待乘客数. 结果表明,新的控制策略可以提升公交系统的运行效率,具有一定的现实指导意义.     

Exploring the effects of cooperative adaptive cruise control on highway traffic flow using microscopic traffic simulation

This paper examines the impact of having cooperative adaptive cruise control (CACC) embedded vehicles on traffic flow characteristics of a multilane highway system. The study identifies how CACC vehicles affect the dynamics of traffic flow on a complex network and reduce traffic congestion resulting from the acceleration/deceleration of the operating vehicles. An agent-based microscopic traffic simulation model (Flexible Agent-based Simulator of Traffic) is designed specifically to examine the impact of these intelligent vehicles on traffic flow. The flow rate of cars, the travel time spent, and other metrics indicating the evolution of traffic congestion throughout the lifecycle of the model are analyzed. Different CACC penetration levels are studied. The results indicate a better traffic flow performance and higher capacity in the case of CACC penetration compared to the scenario without CACC-embedded vehicles.     

我国邮轮制造业发展探析

邮轮经济的蓬勃发展给邮轮制造业带来巨大机遇,而邮轮本身也朝着规模大型化、功能全面化和船龄年轻化的趋势发展。虽然我国造船企业有建造各种船舶的经验,但唯独豪华邮轮尚未建造。文中通过分析世界邮轮制造业现状及我国发展邮轮制造业的必要性和可行性,给出发展我国邮轮制造业的建议。     

信息共享机制融入国际邮轮专业的课程教学改革

国际邮轮经济的发展,促使国内很多的交通、旅游院校开设了国际邮轮专业。为了与国际邮轮经济接轨,本文在研究国际邮轮专业课程设置的过程中,详细阐述并大胆引进信息共享机制,以促进国内国际邮轮专业与国外无缝接轨。     

Manual vs. adaptive cruise control – Can driver’s expectation be matched?

The role of the driver in the longitudinal car following control task will change from operator to supervisor with most of manual control replaced by automation as adaptive cruise control (ACC) technologies become commonplace. The extent to which manual control can be replaced by ACC will be determined by many factors. An important issue is the compatibility between ACC performance and the driver’s expectations.This paper describes the results of a simulation study of the performance of ACC relative to driver expectation. Driver’s expectation is quantitatively defined as the expected deceleration rate for several time-to-collision (TTC) levels, and an absolute minimum TTC that drivers tried to avoid in all cases. A two-level ACC algorithm was used to simulate the performance of an ACC equipped vehicle in various scenarios, and the result was compared to the driver’s expectations. The investigation has focused on scenarios which ACC is able to manage technically, but where driver expectations might be breached.By systematically changing variables such as the parameters of the ACC algorithms, traffic scenarios and time-headway settings, a large number of situations have been tested. The results have revealed that whilst appropriate ACC settings can be found which will meet the driver’s expectations, the ACC settings that are most capable in a range of traffic conditions are not necessarily the most user-friendly. A discussion on the implications of the findings is also presented.     

Truck platooning on uphill grades under cooperative adaptive cruise control (CACC)

This paper examines CACC truck platooning on uphill grades. It was found that the design of CT policy should consider the effects of low crawl speeds on significant upgrades. Three simple solutions, which have different impacts on traffic flow efficiency, are proposed. Furthermore, truck platoons, controlled by a state-of-the-art CACC model, become asymptotically unstable beyond some critical grade. The errors are permanent, suggesting that trucks fail to re-engage after the upgrade. This occurs by complex interactions between the CACC control and the bounded acceleration capabilities of trucks. New control concepts are developed to complement the existing control model and achieve asymptotic (and string) stability. The instability mechanisms and new control concepts are not specific to the control model used.     

Fuel and time savings by flying continuous cruise climbs: Estimating the benefit pools for maximum range operations

This paper estimates the benefits, in terms of fuel and time, which continuous climb operations can save during the cruise phase of the flights, assuming maximum range operations. Based on previous works, a multiphase optimal control problem is solved by means of numerical optimization and using accurate aircraft performance data from the manufacturer. Optimal conventional trajectories (subject to current air traffic management practices and constraints) are computed and compared with ideal continuous operations only subject to aircraft performance constraints. Trip fuel and time for both concepts of operations are quantified for two aircraft types (a narrow-body and a wide-body airplane) and a representative set of different trip distances and landing masses. Results show that the continuous cruise phase can lead to fuel savings ranging from 0.5% to 2% for the Airbus A320, while for an Airbus A340 the dispersion is lower and savings lie in between 1% and 2%. Interestingly, trip time is also reduced between 1% and 5%.     

基于模型预测控制的CACC系统通信延时补偿方法

为确保通信延时条件下协同式自适应巡航控制(CACC)系统的弦稳定性,利用模型预测控制(MPC)和长短期记忆(LSTM)预测方法,研究CACC系统中车辆协同控制下的通信延时补偿方法;基于车辆队列四元素架构理论,构建了包括车辆动力学模型、间距策略、网络拓扑和MPC纵向控制器的系统模型,并综合考虑2范数和无穷范数弦稳定性条件,提出了CACC车辆队列混合范数弦稳定性量化指标,最终形成协同式车辆队列建模与评价体系;设计了一种利用前车加速度轨迹(PVAT)作为开环优化参考轨迹的MPC方法,即MPC-PVAT,通过综合考虑队列的跟驰、安全、通行效率和燃油消耗等性能指标,使目标函数趋于最小代价,从而得到当前时刻的最优控制量,并利用庞特里亚金最大值原理对所设计的优化问题进行快速求解;在MPC-PVAT基础上,提出一种基于长短期记忆(LSTM)网络的通信延时补偿方法,即MPC-LSTM,将跟驰车辆的传感器信息输入LSTM网络来预测其前车的运动状态,从而缓解短暂通信延时对车辆队列稳定性的影响。仿真测试结果表明：MPC-LSTM可容忍的通信延时上界大于1.5 s,比MPC-PVAT提升了0.8 s,比线性控制器提升了1.1 s;在基于实车数据测试中,当通信延时增加到1.2 s时,MPC-LSTM的弦稳定性指标相比MPC-PVAT提升了20.33%,与线性控制器相比稳定性提升了39.35%。可见,在通信延时较大的情况下,MPC-LSTM对通信延时具有很好的容忍性,从而有效地保证了CACC车辆队列的弦稳定性。     

我国内河干流及港口水域海事巡航监管模式探析

文章在简述我国内河干流及港口海事巡航监管模式的基础上,分析了当前我国巡航监管中存在的问题,并就完善我国内河干流、港口水域海事巡航监管模式进行了探讨。