多模导航模拟器时间同步控制系统设计与实现

在多模导航模拟器的设计过程中,由于需要模拟的导航信号频点较多,使得如何修正由于多个上位机程序启动时间差异导致的数据包不同步,以及如何控制不同中频板卡同步启动以产生时间同步的中频信号成为了关键问题。针对这两个问题,设计并实现了一种应用于基于软件无线电体系架构多模导航信号模拟器的时间同步控制系统。该系统通过由系统计时板对外设板卡同步触发启动控制,驱动软件与外设板卡1s时隙同步控制,以及驱动软件向外设板卡传输数据包的同步控制,实现对各系统频点的时间同步控制,能够支持多模导航信号模拟器长时间持续稳定的工作,具有各系统频点时间同步精度高和系统复杂度低等优点。通过联合定位测试结果表明,采用本控制系统的多模导航模拟器的各系统频点的输出信号是时间同步的。     

北斗系统L频段导航信号的波形设计及仿真

随着全球导航卫星系统(Global Navigation Satellite System,GNSS)的不断增多以及频谱资源的限制,设计更高性能并减小相邻信号间干扰的未来GNSS信号体制成为紧迫任务。通过在信号的兼容性和导航性能约束条件之间的折中,提出北斗系统全球信号体制在L频段采用最小频移键控(Minimum Shift Keying,MSK)调制方式的信号波形设计方案。仿真结果表明,设计的优化信号与同频段相邻信号的频谱重叠程度小,谱安全性较高。同时,优化信号具有优于北斗系统公开服务信号B1C的导航性能,且信号最佳接收的接收机实现复杂度低于授权信号B1A。实际证明,上述成果可应用于北斗系统信号体制的顶层设计中,对进一步提高L频段的导航频谱利用率,以及我国自主的兼容信号体制设计具有参考意义。     

转发式北斗导航卫星信号性能评估的研究与实现

北斗一代在使用过程中存在隐蔽性不良,定位实时性差等问题,为了实现北斗导航信号的性能评估,相对于以往的硬件形式,如硬件接收机、频谱分析仪、矢量网络分析仪等,提出了以软件接收机的方法对北斗导航信号进行性能评估;首先分析了转发式北斗导航信号评估的意义、内容与方法,并采用软件接收机的形式进行评估;然后研究了转发式北斗导航的信号性能评估关键技术,给出了捕获、跟踪、评估参数计算的程序流程;最后根据实测数据在Linux高性能集群系统上进行了测试验证,实现了北斗导航信号的捕获、跟踪以及评估中的评估参数计算;测试结果表明,文章中的设计方法可实现北斗导航信号性能的评估,效果良好,评估内容、指标易于调整,便于软件算法参数的测试、升级,可为后续的卫星导航信号评估以及算法测试等提供了一定的依据。     

电磁导航智能车检测和控制系统的研究

对电磁导航智能车的信号检测、控制系统的设计和实现做了介绍。通过Matlab对不同路径进行了磁场分析,确立了传感器的排布方案,并针对采集的信号进行了后续信号处理电路的设计,完成了信号的采样,确定了控制策略,单片机根据传感器采集的跑道信号通过A/D转换进行分析,通过增量式PID来控制智能车的速度,并通过脉宽控制舵机转角来实现智能车的拐弯,最终实现了能够针对不同路径稳定快速运行的电磁导航智能车的制作。     

某型飞机地面导航仿真器软件总体设计

以PC/104嵌入式计算机为平台的某型飞机地面导航仿真器,模拟导航计算机的空中有关导航功能,实现与飞机实际操作控制台之间的通信,并通过转换电路驱动了相应显示设备,同时实现以太网数据同步监控、显示和处理等。该仿真器为飞行参数分析、处理提供了一个简单可靠、实时的数据源。对仿真器总体设计过程尤其是软件开发过程进行了翔实的介绍,拓宽了广大从事Windows环境下仿真器设计的工程技术人员视野。     

导航吊舱控制计算机设计

夜间低空导航吊舱的核心是控制计算机它是典型的分布式机载计算机，其完成的功能是：吊舱的控制、地形跟随雷达的数据处理、数字扫描变换处理和实现与飞机航空电子的通讯等等。本文将详细介绍导航吊舱控制计算机的硬件设计和系统软件设计。     

机会信号导航综述

全球导航卫星系统(Global navigation satellite system,GNSS)是目前普遍使用的定位手段,其利用多种定位卫星为用户提供全球范围内的高精度位置信息.但由于城市密集区或室内环境对卫星信号的遮挡和吸收作用,使得常用导航方案在这些地区存在定位精度差等问题.机会信号导航(Navigation via signal of opportunity,NAVSOP)通过接收、处理空间中已存在的信号实现对用户的定位,在克服这些问题上优势十分突出,近年来得到学术界的广泛关注.鉴于此,对NAVSOP常用定位方法进行总结,并分析其在不同系统中的适用性,详述不同类型NAVSOP系统的技术特点和研究现状.针对单一导航系统鲁棒性差的问题,从系统工作方式等方面分析NAVSOP在组合导航中应用的优势.最后指出该研究领域中仍然存在的问题,并对进一步的研究方向进行展望.     

基于MSP430的仿生偏振光导航传感器的设计与实现

根据沙漠蚂蚁Cataglyphis的导航机理,采用分段导航算法研制了以MSP430为控制核心的偏振光导航传感器.该传感器利用分段算法通过变化明显的两路电压信号计算导航角,分辨率高,采用混合信号处理器降低传感器功耗,无线通信方式增加了信号传输距离和灵活性,方便应用.分析了传感器导航机理和分段导航算法;设计传感器的硬件电路...     

导航卫星上行注入与测距性能测试系统设计

导航卫星的上行注入与测距性能是卫星导航系统服务精度一个重要保证,设计了一种导航卫星的上行注入与测距性能测试系统;该系统以控制处理计算机为核心,并结合了专用设计的基准频率发生器模块、基准时间发生器模块、注入信号发生器模块和通用商业化仪器,能实时动态地模拟导航卫星在轨期间接收地面注入信号的情形,完成导航卫星上行注入性能测试中电文信息的生成和比对以及上行测距性能测试;该测试系统稳定、灵活,测量精度高,而且可以通过修改测试软件参数来满足新的测试要求,便于测试系统的升级改造。     

基于图像匹配的飞行器导航定位算法及仿真

在飞行器导航定位优化控制的研究中,针对无法获得GPS信号时,长航时飞行器捷联惯导系统存在误差,提出了关于图像地标的飞行器精确定位算法,为实现成像系统对捷联惯导系统的误差校正奠定了基础。利用特定地标在机载摄像机像平面上的图像信息,通过图像变换、匹配定位、坐标变换,解算摄像机空间三维坐标和三个姿态角。再根据摄像机坐标系与机体坐标系的变换关系,推算飞行器精确位置。通过计算机仿真对算法进行了验证,结果表明,提出的算法能够满足GPS不可用时长航的飞行器组合导航精度要求,研究结果对长航时飞行器导航具有一定借鉴和参考价值。     

两导航模块相对导航的研究

主要研究两个导航模块间的相对导航,并实现了两导航模块间相对位置的实时测量。讨论了不同坐标系下定位结果的互相转换。对导航模块输出数据进行了简要的分析,叙述了在Visual Studio编译环境下利用C#语言编写程序实现对定位数据的提取分析,并对两个模块定位信息处理从而实时计算出两个导航模块的相对位置信息。     

机载组合导航系统实际导航性能计算方法

机载组合导航系统的实际导航性能计算是民航实施基于性能的导航(PBN)的关键技术,PBN要求机载组合导航系统能够利用相关数据实现其自身实际导航性能的实时评估计算,从而达到高可靠性要求下的缩小航路间隔,提高空域利用的目的.提出了机载组合导航系统实际导航性能实时计算评估的方法.通过分割卡尔曼滤波器的协方差矩阵获取位置误差矩阵...     

Relative Navigation Approach for Vision-Based Aerial GPS-Denied Navigation

GPS-denied aerial flight is a challenging research problem and requires knowledge of complex elements from several distinct disciplines. Additionally, aerial vehicles can present challenging constraints such as stringent payload limits and fast vehicle dynamics. In this paper we propose a new architecture to simplify some of the challenges that constrain GPS-denied aerial flight. At the core, the approach combines visual graph-SLAM with a multiplicative extended Kalman filter. More importantly, for the front end we depart from the common practice of estimating global states and instead keep the position and yaw states of the MEKF relative to the current node in the map. This relative navigation approach provides simple application of sensor measurement updates, intuitive definition of map edges and covariances, and the flexibility of using a globally consistent map when desired. We verify the approach with hardware flight-test results.     

Imprecise Navigation

Conventional models of navigation commonly assume a navigation agents location can be precisely determined. This paper examines the more general case, where an agents actual location cannot be precisely determined. This paper develops a formal model of navigation under imprecision using a graph. Two key strategies for dealing with imprecision are identified and defined: contingency and refinement. A contingency strategy aims to find an instruction sequence that maximizes an agents chances of reaching its destination. A refinement strategy aims to use knowledge gained as an agent moves through the network to disambiguate location. Examples of both strategies are empirically tested using a simulation with computerized navigation agents moving through a road network at different levels of locational imprecision. The results of the simulation indicate that both the strategies, contingency and refinement, applied individually can produce significant improvements in navigation performance under imprecision, at least at relatively fine granularities. Using both strategies in concert produced significant improvements in performance across all granularities.     

面向民机导航系统的实际导航性能计算方案

随着民用航空运输业的发展,传统导航方式的低性能、低精度问题日益突出,已经无法满足现代民航需求。基于性能的导航（PBN）概念包含了区域导航（RNAV）和所需导航性能（RNP）的全部关键技术,其在水平方向上用实际导航性能（ANP）概念来评价导航性能。提出针对民机在单一导航源和多源导航模式下的实际导航性能评估计算方案,灵活运用精度因子、误差协方差、瑞利分布等概念计算ANP值。通过仿真可知,该方法在单一导航源工作模式下可以将ANP精度提高2%至7%,在多导航源模式下可以将ANP精度提高1%至4%,且两者计算复杂度不会有明显提高,为后续民机实际导航性能计算方法的设计提供了有效的思路。     

Multi-perspective Navigation of Movies

Digital libraries of video are rapidly growing in size and availability through digital networks of computers. The explosion of digital unstructure information, such as video, traveling through the network raises the need for tools that allow video information structuring and “intelligent” access to sequences.In this paper we present a novel video database system, which has been expressly designed to support structured storage of movies. A semiotic formalization for movie logical organization is here introduced and exploited to derive the conceptual schema of an object-oriented movie database. This structure is expressly tailored to enable queries on film technical features and on semantic contents as well, thus allowing feature fusion and access from multiple perspectives. A novel visual interaction scheme is implemented that allows users to formulate queries as filtering operations, that enable focussing on the interesting part of information, while skipping the rest. Formalization of the operators of “perspective” and “filtering” is thereby supplied. Retrieval of stored sequences by iconic motion example is also implemented for accessing sequences by contents. Examples are supplied of interaction with the database and of expressive power of visual query language.     

基于北斗导航系统的兼容式车辆导航系统设计

从现有车辆导航系统的基本原理和组成出发,结合我国自主的北斗卫星导航系统,综合应用通信、控制、GIS等多种技术,提出了一种兼容自主式和中心式车辆导航系统的设计,并重点讨论了控制中心和移动终端的实现方案,控制中心通过采集实时交通信息,进行分析处理后形成最优的路径规划,移动终端根据自身所在的位置区域获取相应的诱导信息,使城市的交通流趋向最优分布,减少车辆在道路上的逗留时间,从而有效地改善城市交通状况,减少交通拥堵.     

Landmark-Based Robot Navigation

Achieving goals despite uncertainty in control and sensing may require robots to perform complicated motion planning and execution monitoring. This paper describes a reduced version of the general planning problem in the presence of uncertainty and a complete polynomial algorithm solving it. The planar computes a guaranteed plan (for given uncertainty bounds) by backchaining omnidirectional backprojections of the goal until the set of possible initial positions of the robot is fully contained. The algorithm assumes that landmarks are scattered across the workspace, that robot control and position sensing are perfect within the fields of influence of these landmarks (the regions in which the landmarks can be sensed by the robot), and that control is imperfect and sensing null outside these fields. The polynomiality and completeness of the algorithm derive from these simplifying assumptions, whose satisfaction may require the robot and/or its workspace to be specifically engineered. This leads us to view robot/workspace engineering as a means to make planning problems tractable. A computer program embedding the planner was implemented, along with navigation techniques and a robot simulator. Several examples run with this program are presented in this paper. Nonimplemented extensions of the planner are also discussed.This research was partially funded by DARPA contract DAAA21-89-C0002 and ONR Contract N00014-92-J-1809.     

汽车导航系统

着重分析和介绍了GPS在汽车导航系统中的应用细节,给出了汽车导航系统的原理与结构,它是解决城市交通拥堵的一种高科技手段,是21世纪交通运输管理模式,智能交通系统的发展方向之一。     

Kinematics-Based Navigation Functions

In this paper, we introduce a new family of navigation laws which are based on analytic navigation functions derived using the kinematics equations. These navigation laws combine local and global aspects, and can be used for both indoor and outdoor navigation. The robot's kinematics model is represented in polar coordinates. The analytic navigation functions suggested here are functions of the line-of-sight angle between the robot and the goal, and depend on one or more navigation parameters. The navigation parameters allow us to control the navigation law and, thus, the path of the robot. The choice of the navigation function and its parameters is important, and must satisfy some conditions. Different paths are obtained for different navigation functions and different parameters. This property is used to avoid collision with obstacles. Under this formulation, the number of navigation functions allowing the robot to reach a given goal is infinite. An extensive simulation study shows the effectiveness of the method.