New Developments in Radar and Radio Sensors for Aircraft Navigation

Recent developments in airborne Doppler and ground mapping navigation radars and ground and satellite based radio systems are described. Simultaneous lobing and slope tracking techniques can remove the well-known Doppler sea bias error in fast and slowly moving vehicles. Doppler velocity information can be extracted from coherent forward-looking mapping radars, and high position fixing accuracy can be achieved by synthetic aperture radars. In radio navigation systems, such as Loran, Omega, and satellite systems, direct-ranging and differential techniques greatly reduce the geometric dilution and propagation effects which have plagued conventional radio navigation systems. The advantages gained by mixing of the data from these and other navigation sensors in a digital multisensor system are discussed and approaches for processing these data are suggested.     

Filtering of discontinuous processes arising in marine integratednavigation systems

A refined stochastic model for the errors of the Loran-C radio navigation aid is described, and it is shown how this model can be used to improve the performance of integrated navigation systems. In addition to the usual propagation errors, Loran-C time of arrival measurements are occasionally plagued with sudden intermittent errors of a particular magnitude and caused by receiver cycle selection errors. These result in sudden large jumps in the calculated position solution. The Loran-C error has been modeled as the sum of a diffusion process, representing the normal propagating errors, and a pure jump process of Poisson type, representing the cycle selection errors. A simple integrated navigation system is then described, based on the Loran-C model and the standard dead reckoning (heading and speed) system model. Assuming that the observed process is governed by a linear stochastic difference equation, a recursive linear unbiased minimum variance filter is developed, from which the Loran-C and dead reckoning errors, and hence position and velocity, can be estimated     

陆基超远程无线电导航发展研究

定位导航和授时(PNT)系统是保障现代社会正常运转必不可少的基础设施,为了提供可靠的PNT信息服务,需要研发不依赖于卫星导航的PNT系统。介绍了国内外陆基超远程导航系统的发展情况,提出了发展基于甚低频无线电信号的陆基超远程无线电系统架构、关键技术及发展建议,陆基超远程导航系统可以在卫星导航不可用时提供备份,对于构建冗余可靠的国家PNT体系、保障PNT信息的安全及可靠性具有重要意义。     

地形辅助制导系统

本文叙述一种地形辅助制导系统,用来修正惯性系统或其它导航系统的误差,以提高飞行器的制导精度。这种辅助系统含有一个卡尔曼滤波器,它将飞行器所飞过的实际地形信息与预存的地图进行比较和处理,从而估计出导航系统的误差。对于一般的丘陵地形,辅助制导后的精度可达到数十米的范围。它适用于飞机、巡航导弹、弹道导弹和其它武器运载系统,而且所需的设备简单,易于实现。     

Hybrid Simulation System Study of SINS/CNS Integrated Navigation

In flight tests, to demonstrate the performance of integrated navigation systems, which are strapdown inertial navigation systems/celestial navigation systems (SINS/CNS), will involve a lot of effort and a heavy financial budget. So, it is important to design a functional self-contained hardware in a loop simulation system on the ground for solving the verification of SINS/CNS integrated navigation systems. Aiming at solving the main program, a high precision, versatile and better real-time performance hybrid simulation system of SINS/CNS integrated navigation is presented. The system adopts the design of hardware-functional modularization and software-flow integration, and makes use of a trajectory generator to produce simulated nominal trajectory data which is a uniform reference to signal process, and employs unique time synchronization algorithms to collect actual errors data of inertial sub-system and celestial sub-system. By combining with nominal trajectory data, the data smoothing, all-sky autonomous star map identification and integrated navigation algorithm based on unscented Kalman filtering (UKF), this system can accomplish a lot of system performance testing. It has the features of flexibility and extensibility and can be used to effectively reduce the experimental expense and shorten the development time of integrated navigation system, which is significant for studying algorithm performance, system speciality, and practical application of integrated navigation system.     

月球探测器天文测角/单程无线电时间差分测距/差分测速导航方法

月球探测器高精度导航技术是确保月球探测任务顺利实施的关键技术之一。当前,大多数月球探测器都是利用地面无线电进行导航和控制,但存在可测控弧段短、易受干扰等局限性,且对于月球背面探测,存在无法直接测控的不足。针对上述问题,提出了一种新的基于天文测角/单程无线电差分测距/差分测速的月球探测器组合导航方法。该方法使用了天文星光角距、探测器接收到的来自地面站或中继星的单程无线电时间差分测距和时间差分多普勒测速3种量测信息,可有效抑制星上时钟和频谱仪的时间和频率测量误差。收敛后的平均位置和速度估计误差分别为902.7 m和0.12 m/s,最大的位置和速度估计误差分别为1 548.2 m和0.24 m/s。仿真分析结果表明该方法具有较高自主导航精度。     

Kalman Filter Design Considerations for Space-Stable Inertial Navigation Systems

Terrestrial inertial navigation is typically performed using an instrumented platform stabilized in a ?local-level? configuration for convenient generation of geographic navigation information. The local-level geographic reference must be maintained by torquing the system gyros, a requirement which may be incompatible with high-precision inertial sensors currently under development. Gyro torquing in a gimballed navigation system can be avoided by employing a ?space-stable? mechanization of the platform where an inertial, rather than geographic, reference is used for navigation calculations. The software design problems associated with this concept, especially those related to the application of Kalman filtering, are the principle focus of this paper. Although the space-stable configuration has been used extensively for spacecraft navigation and guidance, it has not been widely applied to terrestrial navigation, either for air or marine applications. The chief problem in this application is to perform navigation in local-level coordinates, using system outputs generated in an inertial reference frame. It can be demonstrated that, although the navigation system error dynamics are identical for the local-level and space-stable configurations, the dynamics of the sensor errors which drive these systems are quite different. These differences in sensor error propagation characteristics impose new requirements for the design of procedures to accomplish system calibration, alignment, and reset. This paper outlines a Kalman filtering approach which is applicable to all of the above procedures, and presents numerical results to demonstrate its effectiveness.     

Stability of the Decentralized Estimation in the JTIDS Relative Navigation

The joint tactical information distribution system (JTIDS) includes a relative navigation capability with which each member can estimate its own position by utilizing the broadcast position estimates of other members plus the measured times of arrival of the radio signals. Previous simulation studies of the system have shown that unrestricted ranging between members can produce unstable navigation errors, but a covariance-based hierarchy may be stable. We have succeeded in proving, analytically, the stability of a closely related organization?a fixed-rank hierarchy. For all ownstate organizations we present time-domain equations for computing estimation-error covariance and for analyzing stability. A simple simulation is able to demonstrate the stability issues.     

一种提高捷联惯性/里程计组合导航系统定位精度的后处理方法

测绘用捷联惯性/里程计组合导航系统多采用离线后处理技术.此类系统利用里程计位移微分获得的速度作为观测量,采用速度匹配,并通过待测路径中预置的Mark点校正航位推算的位置信息.本文建立了基于速度匹配的16维Kalman滤波模型,对全程采样数据进行正反向导航和滤波处理,以估计惯性器件和里程计的误差;在补偿相关误差后,再次进...     

Improvement of strapdown inertial navigation using PDAF

A new application of PDAF (probabilistic data association filter) for improving the accuracy of autonomous strapdown inertial navigation systems (SINS) is presented. The proposed method is a terrain-aided navigation (TAN) algorithm based on landmark detection combined with a classical SINS. It is shown via a set of simulations that the method can improve significantly the precision of autonomous navigation if the landmark spatial density and quality of landmark detectors are good enough. This new concept of navigation called PDANF (probabilistic data association navigation filter) can be integrated with a relatively low cost in existing operational TAN systems     

基于管道-过滤器模式的机载导航数据库格式化技术研究

针对飞行管理系统机载导航数据库应用需求,以管道-过滤器模式的软件架构体系为基础,设计了机载导航数据库格式化软件,实现标准导航数据格式到机载导航数据库格式的转换,生成适用于飞行管理系统的机载导航数据库文件系统。在分析机载导航数据库格式化的需求上,采用一种改进的管道-过滤器模式,通过裁剪和筛选导航数据的方法,降低数据容量。利用Access数据库作为中间数据库,建立不同类别的数据表,实现数据的快速查询和对比。通过实际的验证和应用表明机载导航数据库格式化软件是可行的,生成的机载导航数据库文件系统符合飞行管理系统要求,格式化后的数据是正确的。     

基于双状态卡方故障检测的组合导航系统

故障检验与隔离是利用联邦滤波实现组合导航系统安全可靠运行的关键技术。针对常规残差卡方检验法对于慢变故障检验效果差,以及状态卡方检验受到初值误差、系统噪声和建模误差影响导致子系统被频繁隔离的问题,提出一种改进的SINS/GPS/ADS/DVL组合导航系统故障检验算法。该算法采用2个状态推进器交替地对滤波数据进行重置,避免状态递推器被未检测出来的故障污染。实验结果表明,改进的算法能够有效提高故障检验的灵敏度,增强组合导航系统的可靠性。     

Quality control in integrated navigation systems

Real-time estimation of parameter sin dynamic systems, which becomes increasingly important in the field of high-precision navigation, requires real-time testing of the models underlying the navigation system. A real-time recursive testing procedure than can be used in conjunction with the Kalman filter algorithm is presented, along with diagnostic tools for inferring the detectability of particular model errors. The testing procedure consists of detection, identification, and adaptation. It can accommodate model errors in the measurement model and dynamic model of the integrated navigation system and is optimal in the uniformly-most-powerful-invariant sense     

关于LTN—72R惯性导航系统定位的几个问题

LTN-72R 惯性导航系统是一个高可靠性、全天候、全球惯导系统。它可单套惯导系统工作,也可作三重位置混合系统工作。惯性即时位置可以使用无线电测距和全向信标导航装置自动更新。本文介绍单套惯导系统、三重位置混合、自动无线电位置更新的基本原理和方法。     

Road profile recognition for autonomous car navigation and Navstar GPS support

We discuss autonomous car navigation based on updating dead reckoning (DR) by road profile recognition (RPR). The navigation system requires sensors to detect changes in altitude and driving direction which are installed in modern cars for different purposes (e.g. ABS sensors). The layout of the navigation system is discussed and simulations are carried out over driving distances of approximately 150 km on the basis of realistic road data and ordinary sensor accuracies. Positioning errors of lower than 10 m (standard deviation) are observed. To achieve this accuracy the synchronization error between measured and mapped data must be continually estimated. The introduced navigation method is ideal to complete present commercial car navigation systems using Navstar GPS.     

Intelligent SINS/RDSS Integrated Algorithms for Land Vehicle Navigation

This is a discussion of the design of strap-down inertial navigation systems (SINS) and radio determination satellite service (RDSS) integrated navigation algorithms. The research aims at testing the effectiveness of artificial intelligence (AI)-aided Kalman filtering (KF) approaches for land vehicle applications. A back-propagation neural network (BPNN)-aided K*F algorithm and a fuzzy inference-based KF algorithm are presented in order to overcome the time delay of RDSS positioning provided by a double-star positioning system in China. Traditional KF causes biased solutions, and indeed, leads to filter instability easily since the time delay of RDSS positioning, in an active mode, is hard to be modeled and sometimes suffers from RDSS outages. Therefore, a fuzzy inference is used to correct the variance matrix of KE measurement noises adaptively; and a trained BPNN corrects the outputs of the Kalman filter. The algorithms proposed herein have been verified on real SINSIRDSS data. collected in land vehicle tests and are compared with other approaches. The results demonstrate that fuzzy inference-based KF algorithms improve the positioning accuracy to over 40 % better than KF algorithms, and BPNN-aided KF algorithms have the same precision as GPS which is the reference station In dynamic experiments without RDSS outages. The test results with RDSS outages indicate that the fuzzy inference-based KF is feasible but with positioning errors of hundreds of meters, so the BPNN-aided KF is designed to efficiently compensate for RDSS outages and improve system performance.     

A new method of single celestial-body sun positioning based on theory of mechanisms

Considering defects of current single celestial-body positioning methods such as discon-tinuity and long period, a new sun positioning algorithm is herein put forward. Instead of tradi-tional astronomical spherical trigonometry and celestial coordinate system, the proposed new positioning algorithm is built by theory of mechanisms. Based on previously derived solar vector equations (from a C1R2P2 series mechanism), a further global positioning method is developed by inverse kinematics. The longitude and latitude coordinates expressed by Greenwich mean time (GMT) and solar vector in local coordinate system are formulated. Meanwhile, elimination method of multiple solutions, errors of longitude and latitude calculation are given. In addition, this algo-rithm has been integrated successfully into a mobile phone application to visualize sun positioning process. Results of theoretical verification and smart phone’s test demonstrate the validity of pre-sented coordinate’s expressions. Precision is shown as equivalent to current works and is acceptable to civil aviation requirement. This new method solves long-period problem in sun sight running fix-ing and improves applicability of sun positioning. Its methodology can inspire development of new sun positioning device. It would be more applicable to be combined with inertial navigation systems for overcoming discontinuity of celestial navigation systems and accumulative errors of inertial nav-igation systems.     

一种基于逆向导航的双轴旋转惯导系统自标定方法

针对惯导系统高精度自标定的需求,提出了一种基于逆向导航的双轴旋转惯导系统自标定方法。通过转位运动对系统误差进行激励,利用Kalman滤波器进行误差估计,同时存储标定数据,待正向导航滤波结束后,利用逆向导航算法对存储数据二次利用,继续进行误差估计,直到所有状态量收敛到一定精度,实现了对数据的充分挖掘。仿真和试验结果表明,该方法可以实现对双轴旋转惯导系统的全参数自标定,提高了标定精度。     

Inertial navigation system synthesis approach and gravity-inducederror sensitivity

A design criterion for improving the performance of the speed-damped inertial navigation system is presented. The single-axis speed-damped system is approached by optimizing the response of the system to a step-function disturbing signal. Butterworth, integral of time-multiplied absolute-value of error (ITAE), and solution-time standard forms are assumed to be the figures of merit for optimizing the system performance. The steady-state RMS (root-mean-square) gravity-induced navigation errors that are excited in the speed-damped system are determined for two gravity uncertainty models. The proposed figures of merit are compared. These comparisons reveal the sensitivity of predicted navigation errors to uncertainties in the gravity statistics, and simplify the choice of a suitable figure of merit for use in the design and error analysis of inertial navigation systems     

Use of MOBITEX wireless wide area networks as a solution toland-based positioning and navigation

The emergence of land-based positioning and navigation systems is the direct result of advancements in technologies relating to geographic information, wireless data communication, and navigation. The increasing demand for these systems has stimulated their rapid development. This paper identifies the wide variety of land-based positioning and navigation systems and classifies them into five groups. The basic system elements that are required in all land-based positioning and navigation systems are also discussed. A proposed system infrastructure that supports the five types of land-based positioning and navigation systems is described. The specific technologies integrated in this proposed infrastructure include the Global Positioning System (GPS), differential GPS, and the MOBITEX wireless wide area packet data networks. Real-time wireless mobile data communication is a key component of any land-based positioning and navigation system. Finally, the evaluation criteria necessary for field testing a pilot land-based positioning and navigation system are presented. This pilot system is used to determine the feasibility and effectiveness of the proposed system design