共查询到20条相似文献，搜索用时 15 毫秒
1.
M. R. Mosavi 《GPS Solutions》2006,10(2):97-107
Position information obtained from standard global positioning system (GPS) receivers has time variant errors. For effective use of GPS information in a navigation system, it is essential to model these errors. A new approach is presented for improving positioning accuracy using neural network (NN), fuzzy neural network (FNN), and Kalman filter (KF). These methods predict the position components’ errors that are used as differential GPS (DGPS) corrections in real-time positioning. Method validity is verified with experimental data from an actual data collection, before and after selective availability (SA) error. The result is a highly effective estimation technique for accurate positioning, so that positioning accuracy is drastically improved to less than 0.40 m, independent of SA error. The experimental test results with real data emphasize that the total performance of NN is better than FNN and KF considering the trade-off between accuracy and speed for DGPS corrections prediction. 相似文献
2.
The weighted mean tropospheric temperature is a critical parameter in the conversion of wet zenith delay to precipitable water vapor in GPS Meteorology. This parameter can not be calculated from the radiosonde data in real time through the conventional methods. In this study, we first discuss the admissible error of weighted mean temperature to enable the accuracy of the conversion better than 1 mm, then summarize the performance of some of the existing methods. An empirical formula is established that satisfies the real-time requirement in GPS meteorology using Sequential Regression Analysis method. It is shown that this real-time formula as compared with other empirical methods is more accurate for local applications. 相似文献
3.
ABSTRACTIntersections are the critical parts where different traffic flows converge and change directions, forming “bottlenecks” and “clog points” in urban traffic. Intersection travel time is an important parameter for public route planning, traffic management, and engineering optimization. Based on low-frequency spatial-temporal Global Positioning System (GPS) trace data, this article presents a novel method for estimating intersection travel time. The proposed method first analyzes the different travel patterns of vehicles through an intersection, then determines the range of an intersection dynamically and reasonably, and obtains traffic flow speed and delay at the intersection under different travel patterns using a fuzzy fitting approach. Finally, the average intersection travel time is estimated from traffic flow speed and delay and intersection range in different travel patterns. Wuhan road network data and GPS trace data from taxicabs were tested in the experiments and the results show that the proposed method can improve the accuracy of travel time estimation at city intersections. 相似文献
4.
提出一种基于单频码和相位观测量的单频精密单点定位方法,将每个观测量的电离层延迟量与接收机钟差、对流层天顶延迟、接收机位置、相位模糊度一起作为未知参数。采用约化参数的平方根信息滤波与平滑算法进行参数解算。该方法适用于实时定位和事后处理,且不需要外部的电离层模型。采用全球分布的32个IGS监测站16 d实测数据进行静态解算试验,结果表明E、N、U方向的RMS分别为0.023 m、0.018 m、0.059 m;基于一组机载GPS数据进行动态解算试验,得到E、N、U方向的RMS(与载波相位动态相对定位结果比较)分别为0.168 m、0.151 m、0.172 m。 相似文献
5.
During past decades, precise point positioning (PPP) has been proven to be a well-known positioning technique for centimeter or decimeter level accuracy. However, it needs long convergence time to get high-accuracy positioning, which limits the prospects of PPP, especially in real-time applications. It is expected that the PPP convergence time can be reduced by introducing high-quality external information, such as ionospheric or tropospheric corrections. In this study, several methods for tropospheric wet delays modeling over wide areas are investigated. A new, improved model is developed, applicable in real-time applications in China. Based on the GPT2w model, a modified parameter of zenith wet delay exponential decay wrt. height is introduced in the modeling of the real-time tropospheric delay. The accuracy of this tropospheric model and GPT2w model in different seasons is evaluated with cross-validation, the root mean square of the zenith troposphere delay (ZTD) is 1.2 and 3.6 cm on average, respectively. On the other hand, this new model proves to be better than the tropospheric modeling based on water-vapor scale height; it can accurately express tropospheric delays up to 10 km altitude, which potentially has benefits in many real-time applications. With the high-accuracy ZTD model, the augmented PPP convergence performance for BeiDou navigation satellite system (BDS) and GPS is evaluated. It shows that the contribution of the high-quality ZTD model on PPP convergence performance has relation with the constellation geometry. As BDS constellation geometry is poorer than GPS, the improvement for BDS PPP is more significant than that for GPS PPP. Compared with standard real-time PPP, the convergence time is reduced by 2–7 and 20–50% for the augmented BDS PPP, while GPS PPP only improves about 6 and 18% (on average), in horizontal and vertical directions, respectively. When GPS and BDS are combined, the geometry is greatly improved, which is good enough to get a reliable PPP solution, the augmentation PPP improves insignificantly comparing with standard PPP. 相似文献
6.
A wavelet-extreme learning machine for low-cost INS/GPS navigation system in high-speed applications
The combined navigation system consisting of both global positioning system (GPS) and inertial navigation system (INS) results in reliable, accurate, and continuous navigation capability when compared to either a GPS or an INS stand-alone system. To improve the overall performance of low-cost micro-electro-mechanical systems (MEMS)-based INS/GPS by considering a high level of stochastic noise on low-cost MEMS-based inertial sensors, a highly complex problems with noisy real data, a high-speed vehicle, and GPS signal outage during our experiments, we suggest two approaches at different steps: (1) improving the signal-to-noise ratio of the inertial sensor measurements and attenuating high-frequency noise using the discrete wavelet transform technique before data fusion while preserving important information like the vehicle motion information and (2) enhancing the positioning accuracy and speed by an extreme learning machine (ELM) which has the characteristics of quick learning speed and impressive generalization performance. We present a single-hidden layer feedforward neural network which is employed to optimize the estimation accuracy and speed by minimizing the error, especially in the high-speed vehicle and real-time implementation applications. To validate the performance of our proposed method, the results are compared with an adaptive neuro-fuzzy inference system (ANFIS) and an extended Kalman filter (EKF) method. The achieved accuracies are discussed. The results suggest a promising and superior prospect for ELM in the field of positioning for low-cost MEMS-based inertial sensors in the absence of GPS signal, as it outperforms ANFIS and EKF by approximately 50 and 70%, respectively. 相似文献
7.
Improving vertical GPS precision with a GPS-over-fiber architecture and real-time relative delay calibration 总被引：2，自引：0，他引：2
Daniel Macias-Valadez Rock Santerre Sophie Larochelle René Landry Jr. 《GPS Solutions》2012,16(4):449-462
A limitation of GPS positioning is that the vertical component is generally two to three times less precise than the horizontal components. In a previous work by R. Santerre of Laval University and G. Beutler of University of Bern, it was shown in simulations that it is possible to improve the GPS vertical positioning precision by using a multi-antenna GPS receiver and a precise calibration technique of the relative hardware delay between the antennas and the receiver. However, no actual implementation of the system was done to prove the concept until now. A new multi-antenna, GPS-over-fiber architecture with real-time delay monitoring, designed and implemented to improve the vertical precision is presented. The improvement in vertical precision arises from the elimination of the relative receiver clock error in single difference, between antennas, and the precision real-time calibration of the relative hardware delay. Experiments were conducted with a zero baseline and a short baseline configuration. The results show, as expected by the theory and the simulations, a two to three times improvement in the precision of the vertical component such that it reached the same level of performance as the horizontal components. These promising results will enable the use of this type of configuration in several applications where the same precision in all 3D components is essential and could not be achieved before with standard GPS positioning techniques. 相似文献
8.
With the increasing availability of location-aware devices, passively collected big GPS trajectory data offer new opportunities for analyzing human mobility. Processing big GPS trajectory data, especially extracting information from billions of trajectory points and assigning information to corresponding road segments in road networks, is a challenging but necessary task for researchers to take full advantage of big data. In this research, we propose an Apache Spark and Sedona-based computing framework that is capable of estimating traffic speeds for statewide road networks from GPS trajectory data. Taking advantage of spatial resilient distributed datasets supported by Sedona, the framework provides high computing efficiency while using affordable computing resources for map matching and waypoint gap filling. Using a mobility dataset of 126 million trajectory points collected in California, and a road network inclusive of all road types, we computed hourly speed estimates for approximately 600,000 segments across the state. Comparing speed estimates for freeway segments with speed limits, our speed estimates showed that speeding on freeways occurred mostly during the nighttime, while analysis of travel on residential roads showed that speeds were relatively stable over the 24-h period. 相似文献
9.
LIU Yanxiong CHEN Yongqi LIU Jingnan 《地球空间信息科学学报》2001,4(1):14-18
1 ＩｎｔｒｏｄｕｃｔｉｏｎＩｎ ｇｒｏｕｎｄ＿ｂａｓｅｄＧＰＳＭｅｔｅｏｒｏｌｏｇｙ ,ｔｈｅ ｐｒｅｃｉｐ ｉｔａｂｌｅｗａｔｅｒｖａｐｏｒｉｓｃｏｎｖｅｒｔｅｄｆｒｏｍｔｈｅｗｅｔｚｅｎｉｔｈｄｅｌａｙｏｆｔｈｅＧＰＳｓｉｇｎａｌ.Ｑｕａｌｉｔａｔｉｖｅｌｙ ,ｔｈｅＰｒｅｃｉｐ ｉｔａｂｌｅＷａｔｅｒＶａｐｏｒ (ＰＷＶ)ｃａｎｂｅｒｅｌａｔｅｄｔｏｔｈｅＷｅｔＺｅｎｉｔｈＤｅｌａｙ (ＷＺＤ)ｂｙＰＷＶ =Ｆ·ＷＺＤＦ =1 0 6ρｖ·Ｒｖ· ｋ3Ｔｍ +ｋ2( 1 )ｗｈｅｒｅｔｈｅｍａｐｐｉｎｇｓｃａｌｅｆａｃｔ… 相似文献
10.
随着经济的快速发展,城市居民出行量迅猛上升。车辆安装GPS导航系统日渐成为趋势,在交通运行方面显示出一定优势。该项目旨在通过感应系统收集交通拥堵状况信息进行量化分析,根据分析结果对车辆路线选择提出建议,以提高交通运行效率。本项目选择上海延安西路的一个区段为例,通过连续一周各个时段的GPS定点道路流量数据收集,获得实时交通信息样例。项目对数据进行时空聚类分析,判别主路和辅路中各个路口的交通拥堵时段,为可否换道省时的时空决策提供依据。案例表明,本研究采用的集成3S技术的时空数据分析和决策方法,可为上海交通状况优化和管理效率提高提供有价值的参考意见。 相似文献
11.
基于GPS基准网的GPS快速静态定位及动态定位方法 总被引：3，自引：0，他引：3
介绍基于GPS基准网进行GSP快速静态定位和动态定位的原理和方法。通过计算基准网改正数及其空间分布，利用内插方法求出用户站的模型误差改正数，不仅可以提高GPS整周模糊度的可靠性，而且能够大大改善GPS测量的精度。利用香港GPS基准网2001年3月的实测数据进行了解算，发现地区在该时间段内受强电离层活动的影响，采用常规GPS测量方法很难确定整周模糊度。利用传统的快速静态定位方法对香港GPS基准网其中一条边（9.2km）24h的观测数据按每15min计算，模糊度确定的准确率仅为45％。采用基准网内插改正数后，仅利用L1的观测数据模糊度确定的准确率提高到100％。点位精度平面位置由2cm提高到5mm，高程精度由4cm提高到3cm。 相似文献
12.
An ActiveX GPS control is presented which can be used to develop software applications with GPS functionality. It translates
the NMEA 0183 interface GPS instructions and triggers event procedures which are used by applications to access the GPS data.
It provides position data in the form of geographic coordinates as well as Universal Transverse Mercator (UTM) projected coordinates.
This control is recommended for the development of general purpose GPS-enabled applications which do not require a high level
of accuracy. A Visual Basic project is also included to demonstrate the use of various features of this control. Finally,
some real-time software applications are discussed which have been developed using this control. These applications include
static point averaging; path tracking; and imagery-based position mapping. 相似文献
13.
Estimation and evaluation of real-time precipitable water vapor from GLONASS and GPS 总被引：1，自引：0，他引：1
Cuixian Lu Xingxing Li Maorong Ge Robert Heinkelmann Tobias Nilsson Benedikt Soja Galina Dick Harald Schuh 《GPS Solutions》2016,20(4):703-713
The revitalized Russian GLONASS system provides new potential for real-time retrieval of zenith tropospheric delays (ZTD) and precipitable water vapor (PWV) in order to support time-critical meteorological applications such as nowcasting or severe weather event monitoring. In this study, we develop a method of real-time ZTD/PWV retrieval based on GLONASS and/or GPS observations. The performance of ZTD and PWV derived from GLONASS data using real-time precise point positioning (PPP) technique is carefully investigated and evaluated. The potential of combining GLONASS and GPS data for ZTD/PWV retrieving is assessed as well. The GLONASS and GPS observations of about half a year for 80 globally distributed stations from the IGS (International GNSS Service) network are processed. The results show that the real-time GLONASS ZTD series agree quite well with the GPS ZTD series in general: the RMS of ZTD differences is about 8 mm (about 1.2 mm in PWV). Furthermore, for an inter-technique validation, the real-time ZTD estimated from GLONASS-only, GPS-only, and the GPS/GLONASS combined solutions are compared with those derived from very long baseline interferometry (VLBI) at colocated GNSS/VLBI stations. The comparison shows that GLONASS can contribute to real-time meteorological applications, with almost the same accuracy as GPS. More accurate and reliable water vapor values, about 1.5–2.3 mm in PWV, can be achieved when GLONASS observations are combined with the GPS ones in the real-time PPP data processing. The comparison with radiosonde data further confirms the performance of GLONASS-derived real-time PWV and the benefit of adding GLONASS to stand-alone GPS processing. 相似文献
14.
Analyzing GNSS data in precise point positioning software 总被引：4，自引：1，他引：3
This work demonstrates that precise point positioning (PPP) can be used not only for positioning, but for a variety of other
tasks, such as signal analysis. The fact that the observation model used for accurate error modeling has to take into consideration
the several effects present in GPS signals, and that observations are undifferenced, makes PPP a powerful data analysis tool
sensitive to a variety of parameters. The PPP application developed at the University of New Brunswick, which is called GAPS
(GPS Analysis and Positioning Software), has been designed and built in order to take advantage of available precise products,
resulting in a data analysis tool for determining parameters in addition to position, receiver clock error, and neutral atmosphere
delay. These other estimated parameters include ionospheric delays, code biases, satellite clock errors, and code multipath
among others. In all cases, the procedures were developed in order to be suitable for real-time as well as post-processing
applications. One of the main accomplishments in the development described here is the use of very precise satellite products,
coupled with a very complete observation error modeling to make possible a variety of analyses based on GPS data. In this
paper, several procedures are described, their innovative aspects are pointed out, and their results are analyzed and compared
with other sources. The procedures and software are readily adaptable for using data from other global navigation satellite
systems. 相似文献
15.
针对复杂区域探测困难、成本较高的问题,设计了一款基于全球卫星导航系统的具有自主巡航功能的环境探测四足爬行机器人及远程监测系统,该机器人以嵌入式STM32F429IGT6芯片作为主控CPU,搭载GPS／北斗定位模块及无线通讯模块,使机器人可以实现自主巡航和自动调节路线.该机器人配备的多种传感器模块可以实现对环境温湿度、风速等参数的采集,同时将收集到的数据进行分析、处理和发送.基于该功能开发的监测系统可以实现对机器人的实时监测,包括运动轨迹和位置信息,并通过无线网络对机器人发送控制指令,实现远程遥控功能.实验结果表明,该自主巡航机器人及其监测系统能够实现精确定位和路线实时调整,提高了机器人探测工作的精准性. 相似文献
16.
The Global Positioning System (GPS), in addition to providing precise navigation and positioning information, produces precise
time and frequency measurements. These measurements result from the atomic clocks in the GPS satellites, which are closely
coupled to Universal Coordinated Time as maintained by the U. S. Naval Observatory [UTC(USNO)]. The application of these measurements
to timekeeping and other systems requiring precise time and frequency is distinct from the navigation/positioning mission.
This article will describe the differences in application of GPS to time and frequency uses. These uses will be described
in the major areas of timekeeping; stationary uses, such as communications networking; and mobile use for aircraft and shipboard
applications. The major considerations in application and operation with precise and less-capable oscilators will be described.
Examples and data will be presented to illustrate the applications. ? 1999 John Wiley & Sons, Inc. 相似文献
17.
为进一步改善精密单点定位（PPP）探测大气可降水量（PWV）的性能，本文提出采用GPS/BDS/GLONASS/Galileo组合PPP进行PWV反演的方法，并利用国内3个MGEX（multi-GNSS experiment）观测站的实测数据，对GPS/BDS/GLONASS/Galileo组合PPP在大气水汽探测方面的性能进行了评估。试验结果表明：相较于GPS PPP、GPS/BDS组合PPP和GPS/GLONASS组合PPP，GPS/BDS/GLONASS/Galileo组合PPP估计天顶对流层延迟（ZTD）的初始化时间分别缩短了33%、26%、20%，且能获得更高精度的ZTD估值和PWV信息，在大气水汽探测方面的性能更优。 相似文献
18.
地籍测量工作是地籍管理和地籍信息系统建设的基础,在地籍测量土地状况利用调查中,查清各类土地的分布和利用状况需要有一个准确的定位。随着GPS测量技术的飞速发展和不断成熟,网络GPS-RTK技术以其高精度和高自动化优势在地籍测量中的作用越来越重要。在手机网络流行的今天,网络GPS的应用也越来越便利。本文结合河南理工大学新校区地籍测量工作,首先介绍网络RTK组成及定位原理,分析了网络RTK测图的关键技术,重点说明了网络GPS-RTK的数据采集作业方法以及数据处理和在地籍测量中的使用步骤,得出了网络GPS是一个快速和准确的测量方法,具有较强的实用性,可以满足地籍测量的需要。 相似文献
19.
针对利用实时浮动车数据估计路段行程时间时存在的数据稀疏性问题,提出了构建三层神经网络模型,以目标路段与邻接路段间的特征关系为输入、目标路段与邻接路段行程时间比值为输出,利用浮动车历史大数据获取路段之间的交通时空关联关系,继而用于路段行程时间的推断。采用武汉市2014年3~7月的浮动车GPS历史数据进行验证,得到的路段行程时间估计值的平均绝对百分比误差小于25%,证明了所提方法的有效性。 相似文献