高精度车载导航定位系统的研究

通过对车载导航系统结构、功能的分析，对车辆的高精度导航定位进行了研究。在常见的卫星导航（GPS）、航位推算（DR）等导航定位的基础上，进一步研究并实现了地图匹配算法，克服了GPS信号受阻时定位间断或失效的缺点，避免了航位推算定位误差随时间的积累。通过大量的跑车试验表明，基于GPS／DR／MM的车辆导航系统，可以高精度地实现车辆定位，进而可以实现地理信息的查询、交通诱导等功能。具有重要的实际应用价值。     

车辆运动方程定位原理的研究及其应用

利用车辆运动方程获取车辆行驶距离,车辆当前位置点处的道路方向作为方向角,根据航位推算原理实时推算车辆位置。通过实地跑车试验分别分析了该定位技术在车载导航系统和监控中心的应用。试验结果显示,在车辆导航系统中该技术能实现GPS盲区内的车辆连续定位功能;在监控中心中,该技术从理论上可以大大减少单个车辆和监控中心之间的信息流量,其实际应用还有待智能交通系统的进一步完善。     

正面碰撞事故中车速推算的改进算法研究

鉴于目前在正面碰撞事故的车速推算中常用的经典算法,其计算结果常与实际情况存在差异,文中在分析刚体碰撞过程中两车的运动状态的基础上,建立了车辆运动微分方程,以推算肇事车碰撞前的行驶速度.实例验证表明:改进算法的计算结果比常用算法的结果更接近PC-CRASH的模拟结果.     

桥位浮雕像片图的制作过程

公路设计文件中的桥位平面图,要求能表示桥位的地形概貌、调治构造物的布设情况及引道线位等。利用航空像片作切割编图和浮雕洗印工艺制作桥位像片图,图面不仅保留了航片的信息,且因有浮雕立体感而显得直观和逼真,也为更新设计文件形式另辟蹊径。桥位浮雕像片图的制作有三个流程。如图1所示。一、搜集航片和切割编图 1.按桥位处地形图的图幅号到航摄资料保管单位(多为省测绘局)搜集桥位处已有航片,抄录航摄时间、摄影比例尺等航摄数据。     

车辆导航系统应用前景广阔

在世界上，现代车辆导航方面的研究已经具有30多年的历史。它融合了汽车、交通、计算机、通信、系统科学等领域的技术，一直是众多高科技公司和各个大学研究的热点。早期的导航系统主要是利用惯性导航设备如陀螺、罗盘等实现定位车辆方向、进行航位推算等功能。由于该系统使用局限性很大，一直没有得到很好的推广。     

区域综合货运OD推算方法及信息价值研究

结合区域公路、铁路货运的特点,对可获取的多来源信息进行了分析,并用于基年货运OD矩阵的推算.建立了基于模糊规划理论的多源数据OD推算模型及算法,并通过江苏省综合货运OD推算的实例对多源信息的信息价值进行了分析,用于反馈指导多源信息的进一步收集.结果表明,模糊数学的引入有助于解决多源数据带来的不确定性问题,提高OD推算精度.另一方面,路段流量、子区域OD量,以及集计OD量的数值价值相对较大,而且路段流量当中,高流量数据较随机流量数价值更高.     

恶劣天气下多航空器改航路径的仿真优化算法

针对恶劣天气下区域管制区内,多航空器改航路径规划中缺乏降低管制员工作总负荷的考虑.以贵阳区域管制区为例,研究了恶劣天气下多航空器改航路径的仿真优化算法.采用灰色模型预测飞行受限区的动态影响范围;利用几何算法预先规划可供选择的改航路径;改进离散粒子群优化算法的运算规则;以整个区域管制区内改航总路径最短和管制员工作总负荷最...     

可直接计算转向流量的改进型DIAL交通分配算法

为了在交通分配中直接计算转向流量而不是通过事后推算获取,利用转向—路段拓扑关系及其衍生路段上流量守恒的规律,对Logit交通分配中最常用的DIAL算法进行改进。改进后的DIAL算法既继承了原算法的基本结构和全部优点,又可在得到路段流量的同时直接计算转向流量,且能避免传统的FURNESS、FRATOR等事后推算模型在进行路段流量至转向流量迭代推算时的过大计算量及其他缺点。最后通过一个经典算例验证了该算法的有效性。     

OD出行矩阵的容量限制推算方法

现有OD矩阵反推算法大多不适用于拥挤路网，本文提出的容量限制OD矩阵推算方法考虑了交通量和通行能力间的相互关系，示例表明对于拥挤路网，容量限制算法得推算精度大大提高。     

车辆导航系统的发展

车辆导航系统是智能交通系统(ITS)的技术基础,了解导航系统的发展进程对车辆导航系统的开发和ITS的建设有着重要的意义。大约18年前,第一代导航系统进入市场,它将航位推算单元与1张地图结合就能完成定位功能。自从引进全球定位系统和数字化的地图后,导航系统的精确性得以保证,同时,随着通信和计算机系统的更新,路线的计算速率也大大提高,目前,导航系统还在不断发展。本文还就目前DAB、TPEG等数据发射技术作了一些概述。     

基于自适应卡尔曼滤波的轮速信号处理技术

分析了轮速信号的检测误差,建立了轮速估计的系统状态空间模型,采用了用于轮速估计的自适应卡尔曼滤波算法.利用MATLAB进行了仿真,验证了算法的有效性.实车试验表明,滤波后的轮速信号延时小,响应速度快,平滑效果比较理想,可以用来直接估计车速.     

电动助力转向系统回正控制算法研究

提出了一种电动助力转向系统回正控制算法以提高转向盘的回正性。开发了一种基于转向盘转角估计的PID控制算法，该控制算法不需要转向盘转角或者电动机转速传感器，降低了控制系统的成本。同时，对提出的控制算法进行了仿真，并与其它回正控制算法的试验进行对比，结果证实此算法可提高转向盘的回正性和稳定性。     

Vehicle sideslip estimation and compensation for banked road

The sideslip driving status is of fundamental importance to the stability of a vehicle. This paper presents a practical vehicle sideslip driving status estimation method that uses ESP (electronic stability program) sensors. ESP sensors such as wheel speed, lateral acceleration, yaw rate and steering wheel angle sensors are used to determine the sideslip driving status and distinguish a banked road. This estimation algorithm contains front-rear sideslip and banked road detection methods. The proposed sideslip estimation algorithm was designed to use the analytical redundancy of these sensors and Lagrange interpolation methods. The performance and effectiveness of the proposed estimation and compensation algorithm were investigated using vehicle tests. This paper presents the results of two cases that were used for the experimental verification: a curved flat road and banked road.     

An alternative to FASTSIM for tangential solution of the wheel–rail contact

In most rail vehicle dynamics simulation packages, tangential solution of the wheel–rail contact is gained by means of Kalker's FASTSIM algorithm. While 5–25% error is expected for creep force estimation, the errors of shear stress distribution, needed for wheel–rail damage analysis, may rise above 30% due to the parabolic traction bound. Therefore, a novel algorithm named FaStrip is proposed as an alternative to FASTSIM. It is based on the strip theory which extends the two-dimensional rolling contact solution to three-dimensional contacts. To form FaStrip, the original strip theory is amended to obtain accurate estimations for any contact ellipse size and it is combined by a numerical algorithm to handle spin. The comparison between the two algorithms shows that using FaStrip improves the accuracy of the estimated shear stress distribution and the creep force estimation in all studied cases. In combined lateral creepage and spin cases, for instance, the error in force estimation reduces from 18% to less than 2%. The estimation of the slip velocities in the slip zone, needed for wear analysis, is also studied. Since FaStrip is as fast as FASTSIM, it can be an alternative for tangential solution of the wheel–rail contact in simulation packages.     

结合卡尔曼滤波器的车辆主动悬架轴距预瞄控制研究

利用轴距预瞄信息，即前后轮路面输入之关系，同时结合卡尔曼滤波器作为状态估计器，本文提出了一种算法用于车辆悬架控制律的设计，根据模拟结果，研究了算法的可行性，分析了卡尔曼滤波器对状态变量的估计精度，以及轴距预瞄控制对进一步改进车辆性能的潜力。     

电动助力转向系统回正控制策略研究

在分析电动助力转向系统回正模型的基础上,提出了电动助力转向回正控制算法。尝试直接采用扭矩信号作为转向盘转角估计的依据,并以此为基础提出不需配置转角传感器的回正控制策略。在matlab中建立了电动助力转向系统的模型,并利用Simulink工具箱对算法进行了仿真。仿真结果表明,所提出的回正控制策略能提高转向盘的回正性能,并为台架试验打下了基础。     

一种基于加速度及轮速信息的参考车速估计方法

以两轮驱动轿车为研究对象,提出了一种基于加速度及轮速信息的参考车速估计方法。以Kalman滤波为基本算法,结合试验分析,通过估计系统噪声特征和修正量测方程,改进了算法对加速度量测信号静态偏差变化的跟踪能力,提高了参考车速的估计精度。利用该方法估计参考车速具有不依赖大量试验、计算量小的特点,适于实车应用。     

Vehicle velocity estimation using effective inertia for an in-wheel electric vehicle

In this study, a vehicle velocity estimation algorithm for an in-wheel electric vehicle is proposed. This algorithm estimates the vehicle velocity using the concept of effective inertia, which is based on the motor torque, the angular velocity of each wheel and vehicle acceleration. Effective inertia is a virtual mass that changes according to the state of a vehicle, such as acceleration, deceleration, turning or driving on a low friction road. The performance of the proposed vehicle velocity estimation algorithm was verified in various conditions that included straight driving, circle driving and low friction road driving using the in-wheel electric vehicle that was equipped with an in-wheel system in each of its rear wheels.     

A new method for wheel–rail contact force continuous measurement using instrumented wheelset

With the aim of improving the continuous measurement of wheel–rail contact force by instrumented wheelset, instead of solving the non-linear equations, we proposed a new method based on state space theory. With this new method, the wheel–rail contact force can be calculated by the recurrence relation and the signals from strain gauge bridges on wheel web. The implementation of continuous instrumented wheelset is quite general and simplified, due to the specific bridging scheme is not necessary. It means that continuous measurement of the contact force could be realised with a simple bridging scheme, even as simple as discrete instrumented scheme. In this work, we first demonstrated and discussed the effectiveness and accuracy of this new method by estimation results with the numerical simulations, and we also applied this new method to two field tests, including one was conducted in a loop test line using a high-speed train and the other one was conducted in an urban line with a light rail vehicle. In a word, this new method is proved to be an effective way to monitor the wheel–rail contact force of rail vehicle track system.     

Closed-loop snowplow applicator control using road condition measurements

Closed-loop control of a snowplow applicator, based on direct measurement of the road surface condition, is a valuable technology for the optimisation of winter road maintenance costs and for the protection of the environment from the negative impacts of excessive usage of de-icing chemicals. To this end, a novel friction measurement wheel is designed to provide a continuous measurement of road friction coefficient, which is, in turn, utilised to control the applicator automatically on a snowplow. It is desired that the automated snowplow applicator deploy de-icing materials right from the beginning of any slippery surface detected by the friction wheel, meaning that no portion of the slippery road surface should be left untreated behind, as the snowplow travels over it at a reasonably high speed.

This paper describes the developed wheel-based measurement system, the friction estimation algorithm and the expected performance of the closed-loop applicator system. Conventional and zero velocity applicators are introduced and their hardware time delays are measured in addition to the time delay of the friction estimation algorithm. The overall performance of the closed-loop applicator control system is shown to be reliable at typical snowplowing speeds if the zero velocity applicator is used.