GPS Navigation Research Articles

The Study of GPS Vision Navigation System of Multi-stage Real-time Matching Algorithm

There exists the problem of low accuracy, instability and costly mobile communication positioning in GPS navigation. The vision orientation system as an auxiliary navigation method can realize the function of high precision positioning within a large range. This paper introduces a matching constraint and layer-by-layer search structure which is suitable for GPS vision navigation system, and puts forward a feature aided multi-stage matching algorithm. The algorithm firstly makes the match of the more obvious characteristics points, then the matched points information are used to determine the subsequent points general disparity range through the geometric constraints, thus improving the matching speed and accuracy. Using different types of outdoor natural topographic map matching experiments were conducted. Experimental results show that the multi-stage matching algorithm introduced in this paper is better than the basic area matching algorithm in matching accuracy and speed.

On the use of INS to improve Feature Matching

Abstract. The continuous technological improvement of mobile devices opens the frontiers of Mobile Mapping systems to very compact systems, i.e. a smartphone or a tablet. This motivates the development of efficient 3D reconstruction techniques based on the sensors typically embedded in such devices, i.e. imaging sensors, GPS and Inertial Navigation System (INS). Such methods usually exploits photogrammetry techniques (structure from motion) to provide an estimation of the geometry of the scene. Actually, 3D reconstruction techniques (e.g. structure from motion) rely on use of features properly matched in different images to compute the 3D positions of objects by means of triangulation. Hence, correct feature matching is of fundamental importance to ensure good quality 3D reconstructions. Matching methods are based on the appearance of features, that can change as a consequence of variations of camera position and orientation, and environment illumination. For this reason, several methods have been developed in recent years in order to provide feature descriptors robust (ideally invariant) to such variations, e.g. Scale-Invariant Feature Transform (SIFT), Affine SIFT, Hessian affine and Harris affine detectors, Maximally Stable Extremal Regions (MSER). This work deals with the integration of information provided by the INS in the feature matching procedure: a previously developed navigation algorithm is used to constantly estimate the device position and orientation. Then, such information is exploited to estimate the transformation of feature regions between two camera views. This allows to compare regions from different images but associated to the same feature as seen by the same point of view, hence significantly easing the comparison of feature characteristics and, consequently, improving matching. SIFT-like descriptors are used in order to ensure good matching results in presence of illumination variations and to compensate the approximations related to the estimation process.

Low-frequency, self-sustained oscillations in inductively coupled plasmas used for optical pumping

We have investigated very low frequency, on the order of one hertz, self-pulsing in alkali-metal inductively-coupled plasmas (i.e., rf-discharge lamps). This self-pulsing has the potential to significantly vary signal-to-noise ratios and (via the ac-Stark shift) resonant frequencies in optically pumped atomic clocks and magnetometers (e.g., the atomic clocks now flying on GPS and Galileo global navigation system satellites). The phenomenon arises from a nonlinear interaction between the atomic physics of radiation trapping and the plasma's electrical nature. To explain the effect, we have developed an evaporation/condensation theory (EC theory) of the self-pulsing phenomenon.

Effects of Reentry Plasma Sheath on the Polarization Properties of Obliquely Incident EM Waves

A novel and simple analytical technique referred to as transmission line analogy is developed and modified to study the transmission properties of the perpendicular polarized wave and the parallel polarized wave obliquely incident on the reentry plasma sheath. Based on the transmission coefficients, the effects of the plasma sheath on the polarization property of obliquely incident electromagnetic (EM) waves are studied. Taking the GPS navigation right hand circularly polarized wave as an example, the influences of incident angle and plasma parameters, including the electron density and the collision frequency on the EM wave's polarization property are studied. Numerical results indicate that the larger the incident angle and the lower the collision frequency is, the worse the deterioration of the polarization property. In addition, the polarization property deteriorates most seriously when the cutoff frequency of the peak electron density is closest to the frequency of the EM waves.

Simple GPS Automatic Navigation Design

GPS vehicle navigation technology is the GPS technology emerges along with the rapid development of embedded technology, the auto industry, the market ofmore variety of products GPS navigation based on quality, technology gap, doesa variety of GPS products. This paper analyzes the development status ofdomestic and foreign vehicle navigation system at present, the GPS vehicle navigation system was discussed, to construct the hardware system based on embedded development board as the core, build of the vehicle navigation systembased on WinCE, using EVC and eSuperMap tool software, design of intelligent navigation system the electronic navigation maproute search.

Design and Research of Quadcopter Navigator

This paper studies the autonomous navigation equipment of Quadcopter. SINS/GPS integrated navigation technology, ultrasonic ranging and barometric altimeter is used in the autonomous navigation system. Navigation board includes measuring height subsystem and measurement position subsystem. The former includes an inertial navigation module and GPS module using the Kalman filter for data fusion, which gets a more accurate and stable location information. Quadcopter height measurement subsystem, using ultrasound and barometers. Complementary filter for effective data fusion, is used to ensure the reliability of height measurement.

Real-Time Positioning Accuracy Analysis of Single-Frequency GPS Based on Ionosphere Grid Products

Firstly, this paper introduces the common methods and accounts for the advantage of ionosphere grid products for correcting ionosphere errors with single-frequency GPS, according the analysis that ionosphere grid product can effectively ameliorate errors of single-frequency GPS navigation and positioning. In detail, this article gives the establishment, forecast and operation methods of ionosphere grid products, and introduces the method that calculates the VTEC (Vertical Total Electronic Contents) values of the geocentric latitude of the ionospheric pierce point, the VTEC values of four-point interpolation models and the single-layer mapping function. It’s also compares different pairs of ionosphere correction data and satellite ephemeris which use to analyze the impact of real-time positioning accuracy of single-frequency GPS. The experiments prove that the predicted ionosphere grid products can obviously improve the precision for single-frequency users, and have some practical values for single-frequency positioning and orbit determination.

Extreme Space Weather Impact: An Emergency Management Perspective

AbstractIn 2010, the Department of Homeland Security's Federal Emergency Management Agency (FEMA) partnered with the National Oceanic and Atmospheric Administration's Space Weather Prediction Center (SWPC) to investigate the potential for extreme space weather conditions to impact National Security/Emergency Preparedness communications—those communications vital to a functioning government and to emergency and disaster response—in the United States. Given the interdependencies of modern critical infrastructure, the initial systematic review of academic research on space weather effects on communications expanded to other critical infrastructure sectors, federal agencies, and private sector organizations. While the effort is ongoing, and despite uncertainties inherent with this hazard, FEMA and the SWPC did draw some conclusions. If electric power remains available, an extreme space weather event will result in the intermittent loss of HF and similar sky wave radio systems, minimal direct impact to public safety line‐of‐sight radio and commercial cellular services, a relatively small loss of satellite services as a percentage of the total satellite fleet, interference or intermittent loss of satellite communications and GPS navigation and timing signals, and no first‐order impact to consumer electronic devices. Vulnerability of electric power to an extreme geomagnetic storm remains the primary concern from an emergency management perspective, but actual impact is not well understood at present. A discussion of potential impacts to infrastructure from the loss of electric power from any hazard is provided using the 2011 record tornado outbreak in Alabama as an example.

최소신장트리를 이용한 무방향 그래프의 점대점 최단경로 탐색 알고리즘

본 논문은 실시간 GPS 항법시스템에서 최단경로 탐색에 일반적으로 적용되고 있는 Dijkstra 알고리즘을 양방향 통행로(무방향그래프)로만 구성된 도로에 적용하고 문제점을 개선한 알고리즘을 제안하였다. Dijkstra 알고리즘은 방향 그래프에서 출발 노드부터 시작하여 그래프의 모든 노드에 대한 최단경로를 결정하기 때문에 알고리즘 수행에 많은 메모리가 요구되어 실시간으로 정보를 제공하지 못할 수도 있다. 이러한 문제점을 해결하고자, 본 논문에서는 무방향 그래프에 적합하도록 출발과 목적지 정점을 제외한 경로 정점들에 대해 최단경로를 설정하고, 출발 정점부터 시작하여 정점 유출 간선들에 대해 최단경로 설정 간선들과 일치하는 간선들을 모두 선택하는 방식으로 한 번에 다수의 정점들을 탐색하는 방법을 택하였다. 9개의 다양한 무방향 그래프에 제안된 알고리즘을 적용한 결과 모두 최단경로를 탐색하는데 성공하였다. 또한, 수행 속도 측면에서 Dijkstra 알고리즘보다 약 60%를 단축시키는 효과를 얻었으며, 알고리즘 수행에 필요한 메모리도 월등히 적게 요구되었다. This paper proposes a modified algorithm that improves on Dijkstra's algorithm by applying it to purely two-way traffic paths, given that a road where bi-directional traffic is made possible shall be considered as an undirected graph. Dijkstra's algorithm is the most generally utilized form of shortest-path search mechanism in GPS navigation system. However, it requires a large amount of memory for execution for it selects the shortest path by calculating distance between the starting node and every other node in a given directed graph. Dijkstra's algorithm, therefore, may occasionally fail to provide real-time information on the shortest path. To rectify the aforementioned shortcomings of Dijkstra's algorithm, the proposed algorithm creates conditions favorable to the undirected graph. It firstly selects the shortest path from all path vertices except for the starting and destination vertices. It later chooses all vertex-outgoing edges that coincide with the shortest path setting edges so as to simultaneously explore various vertices. When tested on 9 different undirected graphs, the proposed algorithm has not only successfully found the shortest path in all, but did so by reducing the time by 60% and requiring less memory.

Development of state estimation system with INS, magnetometer and carrier phase GPS for vehicle navigation

This paper presents a real-time state estimation system for vehicles using inertial sensors, magnetic sensors and GPS receivers with carrier phase measurement capability. The article concentrates on the precise attitude estimation. A real-time method for carrier phase integer ambiguity determination is described. The state estimation algorithm is a two level extended Kalman filter. The results are tested for real movement of a car and a sail-plane.

Stochastic modeling of atomic receiver clock for high integrity gps navigation

The Global Positioning System (GPS) was designed as a passive radio navigation system to provide positioning capability without the need for receiver clock synchronization to GPS time. In theory, a GPS receiver equipped with a high-quality receiver clock can provide better system performance. More importantly for integrity-driven navigation applications, the additional redundancy provided by a clock dynamic model can increase fault detection performance and availability for receiver autonomous integrity monitoring (RAIM). In the work presented here, a stochastic model is used to rigorously account for the time correlation of random errors in high-quality GPS receiver clocks. A batch estimator (BE) is then developed to use GPS measurements collected over time to estimate current user position. The BE incorporates the stochastic clock model to ensure that position errors are properly quantified and, therefore, that navigation integrity is ensured. The resulting improvement in positioning performance is demonstrated using covariance analysis.

A Hybrid Prediction Method for Bridging GPS Outages in High-Precision POS Application

Position and orientation system (POS) is a key technology widely used in remote sensing applications, which integrates inertial navigation system (INS) and GPS using a Kalman filter (KF) to provide high-accuracy position, velocity, and attitude information for remote sensing motion compensation. However, when GPS signal is blocked, the POS accuracy will decrease owing to the unbounded INS error accumulation. To improve the reliability and accuracy of POS, this paper proposes a hybrid prediction method for bridging GPS outages. This method uses radial basis function (RBF) neural network coupled with time series analysis to forecast the measurement update of KF, resulting in reliable performance during GPS outages. In verifying the proposed hybrid prediction method, a flight experiment was conducted in 2011, based on a high-precision Laser POS. Experimental results show that the proposed hybrid prediction method is more effective than two other methods (KF and RBF neural network).

Simplified Orbit Determination Algorithm for Low Earth Orbit Satellites Using Spaceborne GPS Navigation Sensor

ABSTRACT In this paper, the main work is focused on designing and simplifying the orbit determination algorithm which will be used for Low Earth Orbit (LEO) navigation. The various data processing algorithms, state estimation algorithms and modeling forces were studied in detail, and simplified algorithm is selected to reduce hardware burden and computational cost. This is done by using raw navigation solution provided by GPS Navigation sensor. A fixed step-size Runge-Kutta 4th order numerical integration method is selected for orbit propagation. Both, the least square and Extended Kalman Filter (EKF) orbit estimation algorithms are developed and the results of the same are compared with each other. EKF algorithm converges faster than least square algorithm. EKF algorithm satisfies the criterions of low computation burden which is required for autonomous orbit determination. Simple static force models also feasible to reduce the hardware burden and computational cost.

The spatio-spectral localization approach to modeling VTEC over the western part of the USA using GPS observations

The precise ionosphere modeling is crucial and remains a challenge for GPS positioning and navigation, as well as many other Earth observation systems. In this research, two approaches have been proposed to model the vertical total electron content (VTEC) of the ionosphere using spherical slepian function. For the two-dimensional case, VTEC has been modeled in a sun-fixed reference frame and the three-dimensional approach based on the system of the three-dimensional base functions has been defined as the tensor product of the spherical slepian function for the longitude and latitude in an Earth-fixed reference frame, and the polynomial B-spline function for time. Rather than the spherical harmonics, the spherical slepian functions can be employed to produce the locally and globally orthogonal bases to optimally represent the data in any arbitrary region up to a given degree. The spherical slepian functions have been applied to the real data obtained from the ground-based GPS observation across the western part of the USA.

Centimeter-scale GPS coming to Japan [News

A stranger to Tokyo could easily get lost in its urban canyons. And GPS navigation, stymied by low resolution and a blocked view of the sky, might not be much help. But that won't be the case after 2018. Engineers at Tokyo-based Mitsubishi Electric Corp. report that they're on track to start up the first commercial, nationwide, centimeter-scale satellite positioning technology. As well as spot-on navigation, the technology will also usher in a variety of innovative new applications, its proponents say.

Nontarget effects of aerial mosquito adulticiding with water-based unsynergized pyrethroids on honey bees and other beneficial insects in an agricultural ecosystem of north Greece.

We assessed the nontarget effects of ultra-low-volume (ULV) aerial adulticiding with two new water-based, unsynergized pyrethroid formulations, Aqua-K-Othrine (FFAST antievaporant technology, 2% deltamethrin) and Pesguard S102 (10% d-phenothrin). A helicopter with GPS navigation technology was used. One application rate was tested per formulation that corresponded to 1.00 g (AI)/ha of deltamethrin and 7.50 g (AI)/ha of d-phenothrin. Three beneficial nontarget organisms were used: honey bees (domesticated hives), family Apidae (Apis mellifera L.); mealybug destroyers, family Coccinellidae (Cryptolaemus montrouzieri Mulsant); and green lacewings, family Chrysopidae (Chrysoperla carnea (Stephens)). No significant nontarget mortalities were observed. No bees exhibited signs of sublethal exposure to insecticides. Beehives exposed to the insecticidal applications remained healthy and productive, performed as well as the control hives and increased in weight (25-30%), in adult bee population (14-18%), and in brood population (15-19%).

Study on GPS Navigation Navigation System

Currently, GPS global positioning system has been in the areas of precise positioning, navigation, timing has been widely used. By GPS-OEM combined with computer and communications technologies, users are able to easily and independently developed to meet the specific needs of GPS systems. Design system based on GPS navigation navigation system requirements package, in-depth study of the main factors affecting the precision of navigation. Several factors made corresponding solutions, implements navigation navigation system the main functions of the software.

Mobile positioning via fusion of mixed signals of opportunity

GPS is known to be susceptible to interference, jamming, blockage, and attenuation especially in urban and indoor environments. The development of positioning systems in GPS-limited environments is of great interest for both military and commercial location-based applications. In such environments, signals of opportunity (SOOP) can be explored to supplement GPS and other navigation systems [5], [9], [10]. By SOOP, we mean those signals that are not originally intended (designed) for positioning but they are ubiquitous: freely available all the time and everywhere (within a certain range).

Potencialidade do gps de navegação garmin 12 xl utilizando um sistema de baixo custo

Desde o início do ano 2000, o uso de receptores de navegação aumentou consideravelmente. Muito se deve à desativação da disponibilidade seletiva ocorrida em maio de 2000. Entretanto, esses receptores não registram as observáveis, somente estimam e armazenam as coordenadas, o que impede o pós-processamento dos dados. Baseados nesse aspecto, alguns softwares foram desenvolvidos e estão disponíveis gratuitamente. Eles permitem a gravação das observáveis GPS do receptor, pseudodistâncias (código C/A) e das medidas da fase da onda da portadora. Esses programas são capazes de ler de e registrar em arquivos binários as informações referentes às observáveis GPS e realizar a conversão de formato binário para o formato RINEX. Este trabalho visa a avaliar o receptor de navegação Garmin 12 XL a partir do uso dos programas livres. Dois experimentos foram realizados na região de Presidente Prudente-SP, empregando o levantamento relativo estático. O processamento foi realizado com intervalos de tempo de 30; 15; 10 e 5 minutos. Os resultados foram comparados com as coordenadas advindas de um receptor geodésico e mostram que, para 98,9% dos pontos, os valores em relação à acurácia planimétrica foram melhores que 0,50 m. A única linha de base cujo valor foi maior ou igual a 0,50 m é o vértice M0001 (linha de base menor que 2 km), referente ao primeiro experimento. Em termos de precisão, os valores não ultrapassaram 0,30 m.

Helmert Transformation of Reference Coordinating Systems for Geodesic Purposes in Local Frames

The real-time conditions may develop a need for data originating from the concrete reference system. Sometimes this can refer to the Gauss-Krüger coordinates and UTM projections with a specific datum. This paper analyses a connection between UTM projection with datum WGS-1984 and Gauss-Krüger coordinates for a wider area of the City of Rijeka, without precise need for making the reference to the specific reference coordinate system. Paper also includes the observations of mathematical frames which define Helmert transformations as tool that enables switching from one reference system to another. Additionally, it discusses the needs and possibilities of described tool within GIS and GPS navigation and possibilities of computer program which can modularly be implemented into the specialized programs for Geodesic purposes.