共查询到19条相似文献，搜索用时 31 毫秒
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2021年4月底,日本国土交通省公布了《面向实现和普及自动驾驶的措施报告与方针》第五版概要方案,这是国土交通省和经济产业省主导下主持起草的推动自动驾驶技术的工作方案,该报告中介绍了过去在自动驾驶技术方面的各项工作和相应举措,并对未来工作方向提出了计划。货车列队驾驶实证试验是其中的重要项目之一,本文梳理介绍该项目5年来所做的工作和阶段性成果,以及未来的目标和实施计划。 相似文献
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前不久,美国电动车及能源公司特斯拉向车主推送了最新的系统更新,自动辅助驾驶系统(Autopilot)功能进一步升级,新增“相邻车道速度调整”和“自动巡航停车标志警告”功能,支持汽车根据道路上其他车辆的速度调整自身速度与感应前方的行驶状态。据推特用户上传的更新说明图片可知,“相邻车道速度调整”功能是指汽车可根据道路上其他车辆的速度来调整自身的速度。 相似文献
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自动驾驶技术不断发展,对路况车辆行人信息的需求日益提高,针对此类情况,应用车路协同技术为自动驾驶预先采集处理分析决策数据,可大大提高自动驾驶技术的准确性. 相似文献
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目前,自动驾驶技术在乘用车领域已获得突破性发展;为提高通行效率和出行安全起到了极大的作用。自动驾驶技术在商用车领域的应用,有望较好解决高昂的人力成本和难以提高的效率等问题。然而,目前自动驾驶技术在货车的应用大多采用跟乘用车同样的标准进行规范,这在实际应用中存在着诸多的问题;例如,在FCW和AEB功能中货车在相同车速的制动距离要远大于乘用车,而其所采用标准规定的碰撞预警时间却并无多大不同,这在实际场景中存在着较大的安全隐患[1,2]。此外,货车质量和体积较大,且较多应用于长途运输,运输过程中会经历包括高温、严寒、山区等多种复杂气候场景,这些都将对货车自动驾驶技术在车辆制动效能、能耗以及多场景应用等方面提出更有针对性规范的要求。本文针对货车的应用场景特点,为其自动驾驶技术应用标准化提出了建议。 相似文献
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高速公路实行的“一卡通”联网收费、无人值守自动发卡系统,利用先进技术解决了高速公路出入口堵塞的难题,大大提高了高速公路的通行效率,“低成本、优服务、高效益”成为高速公路管理部门不懈努力的工作目标。本文主要通过对无人值守自动发卡系统在甘肃高速公路中应用情况的分析,来探讨无人值守自动发卡系统的构成、功能以及发展前景。 相似文献
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自动驾驶是智能汽车和智能交通发展的重要技术方向之一,而公交领域是自动驾驶技术能够落地的重要应用场景。目前,自动驾驶技术在城市客运场景下逐渐由产品测试、封闭测试逐步走向试运营、运营阶段。为了支撑公共汽电车自动驾驶研究,本文综述了自动驾驶技术及自动驾驶公交评价与测试现状,回顾了常规公交运行及服务质量评价维度和方法,归纳了自动驾驶车辆在车辆产品测试、封闭测试及开放道路测试的相关研究及评价方法。进一步指出,认识自动驾驶公交车辆应对开放的道路交通状况下的运营特征,并确定面向运营的技术适用条件,是投入社会市场应用与推广的前提。 相似文献
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作为极具潜力的新型出行方式,共享自动驾驶汽车的出现必将引起居民出行行为的转变。为了研究上海市居民共享自动驾驶汽车的使用意愿及影响因素,本文利用网络问卷调查的RP与SP数据,结合百度地图API数据,构建基于解析逼近估计方法的多项Probit模型。结果显示：共享自动驾驶汽车通勤和非通勤出行中时间价值分别为64.34元/小时和81.55元/小时,弹性分析结果显示居民对于等候时间的敏感性显著高于费用;男性、已婚、高收入、高学历、自由职业者、合乘通勤者、年龄小于18岁的人群,以及家庭有未成年儿童、拥有沪C牌照小汽车的居民使用意愿较强。居民对于共享自动驾驶汽车越了解,使用意愿越强烈,而体验过自动驾驶服务的居民使用意愿更为强烈。 相似文献
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Urban mobility is one of the main concerns of the public authorities in developed countries. In France, household travel surveys are conducted every ten years in major cities to gather weekday mobility data. They enable decision-makers to better understand travel patterns, their change and their determinants, in order to adapt transport infrastructures to the population′s needs. While the automobile has allowed the level of mobility to increase since 1950, an unexpected finding has emerged from recent surveys in most developed countries, namely that there has been a marked decline in car use. Analyses show that this trend is mainly because young adults (18–34 years old) are less likely to acquire a driver′s license. This paper tries to better understand the decrease in the rate of driver′s license holding among young adults in the Lyon conurbation and to quantify the impact of the main explanatory factors in a temporal perspective. It also aims to analyze the consequences of this trend on private car use as a driver for daily trips. It quantifies the influence of economic, socio-demographic and spatial factors on driver ′ s license holding and car use by considering the responses to the last three household travels surveys conducted in the Lyon conurbation area (1995, 2006 and 2015). The temporal dimension allows us to highlight a change in the relationship between young adults and the private car in the French context. 相似文献
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In recent years smartcards have been implemented in many transit systems around the world as a means by which passengers pay for travel. In addition to allowing speedier boardings there are many secondary benefits of smartcard systems including better understanding of travel patterns and behaviour of travellers. Such research is dependent on the smartcard correctly recording the boarding stop, and where available the alighting stop. It is also dependent on the smartcard system correctly aggregating individual rides into trips.This paper identifies causes for why smartcard systems may not correctly record such information. The first contribution of the paper is to propose a set of rules to aggregate individual rides into a single trip. This is critical in the research of activity based modelling as well as for correctly charging the passenger. The second contribution of the paper is to provide an approach to identify erroneous tap-out data, either caused by system problems or by the user. An approach to detecting this phenomenon is provided. The output from this analysis is then used to identify faulty vehicles or data supply using the “comparison against peers approach”. This third contribution of the paper identifies where transit agencies and operators should target resources to improve performance of their Automatic Vehicle Location systems. This method could also be used to identify users who appear to be tapping out too early.The approaches are tested using smartcard data from the Singapore public transport network from one week in April 2011. The results suggest that approximately 7.7% of all smartcard rides recorded the passenger as alighting one stop before the bus stop that they most probably alighted at. A further 0.7% of smartcard rides recorded the passenger as alighting more than one stop before the bus stop that they most probably alighted at. There was no evidence that smartcards overestimated the distance travelled by the passenger. 相似文献
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Banihan Gunay 《运输规划与技术》2013,36(6):627-642
Abstract This paper explores the possibility of detecting certain movements of vehicles that might provide useful information for crime investigations. It is known that existing car following models are interested in microscopic interactions between vehicles in randomly formed pairs. The present work, however, introduces the concept of macroscopic analysis of vehicle positions on a network and the idea of seeking if these movements exhibit any meaningful relationships. First of all detection algorithms are produced for two possible types of detection: (a) was a particular vehicle followed by any vehicle? and (b) did a particular vehicle follow any vehicle? These algorithms assume that every link in the network is equipped with some sort of vehicle identification or tracking device and the identities of all vehicles, such as their number plates, are fed into the program. Then a simulation program is developed to implement the first algorithm (Type (a)), as an example, to visualise the concept. Since the present paper is a preliminary and basic approach to the problem, a number of issues and details requiring further research, together with the directions which could be taken, are also identified and discussed. 相似文献
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With a particular emphasis on the end-to-end travel time prediction problem, this paper proposes an information-theoretic sensor location model that aims to minimize total travel time uncertainties from a set of point, point-to-point and probe sensors in a traffic network. Based on a Kalman filtering structure, the proposed measurement and uncertainty quantification models explicitly take into account several important sources of errors in the travel time estimation/prediction process, such as the uncertainty associated with prior travel time estimates, measurement errors and sampling errors. By considering only critical paths and limited time intervals, this paper selects a path travel time uncertainty criterion to construct a joint sensor location and travel time estimation/prediction framework with a unified modeling of both recurring and non-recurring traffic conditions. An analytical determinant maximization model and heuristic beam-search algorithm are used to find an effective lower bound and solve the combinatorial sensor selection problem. A number of illustrative examples and one case study are used to demonstrate the effectiveness of the proposed methodology. 相似文献
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The advancements in communication and sensing technologies can be exploited to assist the drivers in making better decisions. In this paper, we consider the design of a real-time cooperative eco-driving strategy for a group of vehicles with mixed automated vehicles (AVs) and human-driven vehicles (HVs). The lead vehicles in the platoon can receive the signal phase and timing information via vehicle-to-infrastructure (V2I) communication and the traffic states of both the preceding vehicle and current platoon via vehicle-to-vehicle (V2V) communication. We propose a receding horizon model predictive control (MPC) method to minimise the fuel consumption for platoons and drive the platoons to pass the intersection on a green phase. The method is then extended to dynamic platoon splitting and merging rules for cooperation among AVs and HVs in response to the high variation in urban traffic flow. Extensive simulation tests are also conducted to demonstrate the performance of the model in various conditions in the mixed traffic flow and different penetration rates of AVs. Our model shows that the cooperation between AVs and HVs can further smooth out the trajectory of the latter and reduce the fuel consumption of the entire traffic system, especially for the low penetration of AVs. It is noteworthy that the proposed model does not compromise the traffic efficiency and the driving comfort while achieving the eco-driving strategy. 相似文献
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Various regulations are imposed on shipping to increase energy efficiency and reduce environmental impacts. Alternative fuels and power systems are among the solutions for compliance with these regulations. The power system of a ship may not operate optimally because of the diversity of the operational profile during its lifetime. This article uses an activity-based approach and big data from the Automatic Identification System (AIS) to study the operational profiles of eight ship types operating in Norwegian waters around mainland Norway in 2016. The aim is to identify ship types that can benefit from electric and hybrid propulsion through analysis of their operational profiles. Close to shore, the operational profiles of various ship types are similar, and all ships spend a great proportion of their time with lower loads. As the distance from shore increases, the operational profiles of various ship types follow distinct trends. Among the considered ship types, reefers spend more operational time close to the diesel engine design condition. On the other hand, offshore and passenger ships show the most dynamic operational profiles and spend a large percentage of their operational time with a partial load, away from diesel engine design conditions. Such ships can benefit from hybridisation, diesel-electric propulsion, and other electric concepts, such as batteries and fuel cells. Another option is to downsize diesel engines for better operation while fuel cells and batteries supply peak and partial loads. Operational profiles are plotted and details of the approach are presented in the article. 相似文献
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Literature has shown potentials of Connected/Cooperative Automated Vehicles (CAVs) in improving highway operations, especially on roadway capacity and flow stability. However, benefits were also shown to be negligible at low market penetration rates. This work develops a novel adaptive driving strategy for CAVs to stabilise heterogeneous vehicle strings by controlling one CAV under vehicle-to-infrastructure (V2I) communications. Assumed is a roadside system with V2I communications, which receives control parameters of the CAV in the string and estimates parameters imperfectly of non-connected automated vehicles. It determines the adaptive control parameters (e.g. desired time gap and feedback gains) of the CAV if a downstream disturbance is identified and sends them to the CAV. The CAV changes its behaviour based on the adaptive parameters commanded by the roadside system to suppress the disturbance.The proposed adaptive driving strategy is based on string stability analysis of heterogeneous vehicle strings. To this end, linearised vehicle dynamics model and control law are used in the controller parametrisation and Laplace transform of the speed and gap error dynamics in time domain to frequency domain enables the determination of sufficient string stability criteria of heterogeneous strings. The analytical string stability conditions give new insights into automated vehicular string stability properties in relation to the system properties of time delays and controller design parameters of feedback gains and desired time gap. It further allows the quantification of a stability margin, which is subsequently used to adapt the feedback control gains and desired time gap of the CAV to suppress the amplification of gap and speed errors through the string.Analytical results are verified via systematic simulation of both homogeneous and heterogeneous strings. Simulation demonstrates the predictive power of the analytical string stability conditions. The performance of the adaptive driving strategy under V2I cooperation is tested in simulation. Results show that even the estimation of control parameters of non-connected automated vehicles are imperfect and there is mismatch between the model used in analytical derivation and that in simulation, the proposed adaptive driving strategy suppresses disturbances in a wide range of situations. 相似文献
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The Automatic Vehicle Identification (AVI) system was recently installed in expressway networks in Japan. License plate numbers of passing vehicles are monitored through roadside AVI cameras and then recognized. This paper shows the formulation of origin and destination (OD) matrices estimation model using the observed data with the AVI system. The results of license plate matching between a pair of AVI cameras are involved as the input variables. The formulated model is a least squares model and yields to the linear transformation of the partly observed OD matrices. The model is applied to the Kobe corridor line in the Han-Shin expressway network. It is found that the estimated OD matrix is consistent with the one using the previous mail survey. The proposed estimation method is expected to investigate the day-to-day fluctuations of OD patterns in the expressway network. 相似文献