A Trajectory-Based Map-Matching System for the Driving Road Identification in Vehicle Navigation Systems

Driving road identification is the key issue of a vehicle navigation system that supports various services of intelligent transportation systems. The method for driving road identification is also known as map matching (MM). In spite of the development of MM algorithms, limitations still exist in obtaining the positioning data and preparing candidate roads (CRs) that may result in mismatches in some special difficult road configurations such as flyovers and parallel roads. To overcome the limitations, an integrated trajectory-based MM (tbMM) system is proposed based on the trajectory similarity evaluation method. The system can fuse the information from global positioning systems (GPS) and inertial sensors to generate the vehicle trajectory that represents the vehicle continuous movement in three dimensions. The elevation data of vehicle and roads are involved to enhance the trajectory-based matching process. Also the method employs an optimized mechanism for generating and maintaining CRs. Using the mechanism, separated road segments in a digital map are reorganized in the form of possible driving roads and the topology among them is guaranteed. Moreover, the CRs are obtained considering all the possibilities in determining the driving road so that the valuable historical information can be effectively reserved to provide more reliable matches in ambiguous situations. The tbMM system was evaluated using a number of real-world vehicle-level test datasets in urban areas in Beijing. Also a comparison test was performed to evaluate the driving road identification accuracy against existing MM algorithms. The results show that the tbMM system can provide reliable matches with about 99% accuracy in all the difficult scenarios and outperforms the existing algorithms.     

支撑参数对船舶轴系-轴承-基座系统振动特性影响研究

针对支撑参数改变轴系振动特性问题,建立轴系-轴承-基座系统分析模型,研究轴承支撑刚度、基座支撑刚度等支撑参数对系统振动固有特性、振动传递特性的影响规律,并提出轴系减振设计参数控制方向。分析结果表明：轴系横向振动模态频率对轴承刚度、基座刚度在某些区间较为敏感;轴系横向振动部分稳定模态频率不随支撑参数改变;螺旋桨轴承强基座刚度、弱轴承刚度,有利于降低螺旋桨横向激励力通过轴系向螺旋桨轴承的传递;舱内油润滑轴承支撑参数改变对降低螺旋桨轴承处的振动传递影响较小。     

考虑船舶轴系校中与弯曲振动的轴承优化布置

船舶在航行过程中,螺旋桨所受到的激振力通过船舶轴系传递给船体并引起尾部振动和噪声,给船舶的乘坐舒适性和安全性带来危害。本文利用传递矩阵法分别建立船舶轴系校中数学模型和弯曲振动数学模型,并使用拟定常法得到螺旋桨叶频和二倍叶频的激励力幅值比值,成比例输入到轴系系统当中,设置轴承间距和轴承标高为变量,以尾轴后轴承受力幅值最小为目标函数。在满足船舶轴系校中标准下,对轴承位置的轴向和径向进行双向优化,得到实例的最优布置方案,通过比较优化前后的尾轴后轴承受力响应幅值,可以发现优化效果明显,对船舶轴系设计与布置具有一定的指导意义。     

船用平行轴横接齿轮传动惰轮轴承性能分析

以三机两轴和四机两轴CCG传动设计参数为参考,对平行轴横接齿轮传动惰轮轴承进行性能分析,研究惰轮轴承在高速、重载工况下的性能参数分布及轴承线速度、比压变化对轴承性能参数的影响。计算算例中惰轮轴承所能承受的最大线速度及最大比压,为高参数惰轮轴承的设计提供了理论依据。     

实船主柴油机套合曲轴滑移后的振动分析

柴油机在实船使用中,因种种原因有可能使套合曲轴受力过载而发生套合部位滑移。本文对“华”字号轮主机套合曲轴滑移后作其受力以及轴系扭振影响分析,提出在小滑移量下可不作曲轴套合部位的复位,而采用调整机器定时机构来改善因套合曲轴滑移引起的机器工作粗爆性。实践表明此法是可行的。     

城市轨道交通某型车辆轴温检测系统误报隐性故障问题研究

某型城市轨道交通车辆由A型轴温检测系统升级为B型轴温检测系统后,中央控制单元数据中频繁报出头车3/4轴头CAN1/2路隐性故障,通过更换端部接线箱连接器相应公、母针可解决故障问题。通过对连接器内部针位排布规律、连接器插针插拔力检验数据、连接器安装结构进行综合分析,以及对B型轴温系统工作原理和安装结构进行分析,判断是由于连接器线缆无可靠固定、连接器受车体振动影响、内部插针插拔力不足造成接触电阻异常,进而引起误报隐性故障问题。优化解决方案为:在车下线槽盖板上焊接固定支架,对车下的以连接器悬线进行固定,避免振动对连接器的影响。     

城市轨道交通线路越江长区间内风井设置对通过能力的影响

QIAO Qike(Survey and Design Institute of China Railway Eleventh Bureau (Group) Co., Ltd., 430070, Wuhan, China)     

铰接型有轨电车轴重与轮重计算系统开发

以铰接型有轨电车作为计算模型,阐述了铰接型有轨电车的重心、轴重、轮重的原理以及计算过程。根据推导的计算公式,设计了一套软件系统计算轴重、轮重,软件采用C#语言,基于VS2010平台以及数据库SqlServer2008。该系统具有数据查询、存储、编辑以及删除功能,操作方便,具有实际应用价值。     

半挂汽车及配套件技术发展趋势

随着国家基础设施投资力度的加大 ,公路建设飞速发展 ,半挂牵引车的速度动力也不断提高、完善 ,尤其是半挂汽车悬架、车轴、制动系统等方面要求也不断提高 ,同时对半挂汽车外形、色彩等方面也越来越看重     

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通过建立复合式沥青路面力学模型,采用回归分析,得到层间剪应力和表面剪应力以及沥青层厚度的关系。提出了基于剪切疲劳强度的复合式路面沥青层厚度设计方法,并通过算例进行了计算。