Positioning System Research Papers - Academia.edu (original) (raw)

This paper presents a process of systematization and analysis of the reliability parameters of a proportional hydraulic platform that aims to study position control using hydraulic systems. Currently the positioning systems using hydraulic circuits include mechanical and electronic components and software. These automatic systems involve diverse and complex technologies, for which reason the reliability analysis is difficult. Moreover, the failure modes which can occur in each item can produce distinct effects, increasing the complexity of this analysis. The control of all parameters involved becomes very difficult for the design agents, with consequences for the other phases of the life cycle. In this regard a methodology to systemize the information necessary to obtain a product with reliability is proposed. In this process, hierarchic FTA and FMEA diagrams are used as tools for the systematization of the reliability parameters, and Petri Nets are is used to represent the states a...

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- System Design, Reliability Engineering, Reliability Analysis, Life Cycle

Two different theoretical approaches for determining position using star observations are presented, one matrix-based and the other vector-based. Both approaches are designed for implementation in an autonomous Stellar Positioning System that uses the following measurement sources: an astronomical camera, a clock, and a set of two inclinometers. Before presenting each of the algorithms, the reference frames utilized are defined. The two position estimation techniques are then individually presented, followed by a discussion of real-world gravity and geometry model refinements.

- by Daniele Mortari
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- Positioning System

In this paper a new intelligent identification method of uncertainty bound utilizes an adaptive neurofuzzy inference system (ANFIS) in a feedback scheme is proposed. The proposed ANFIS feedback structure performs better in determining the uncertainty bounds with minimum number of iterations and error. In our proposed technique, the intelligent identified uncertainty weighting function is validated utilizing v-gap to ensure the stability of the designed H controlled system. Our proposed intelligent identification of uncertainty bound is demonstrated on a servo motion system. Simulation and experimental results show that the new ANFIS identifier is more reliable and highly efficient in estimating the best uncertainty weighting function for robust controller design.

- by Rini Akmeliawati
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- Adaptive Control, Motion control, Robust control, Controller Design

People positioning and tracking in 3D indoor environments are challenging tasks due to background clutter and occlusions. Current works are focused on solving people occlusions in low-cluttered backgrounds, but fail in high-cluttered scenarios, specially when foreground objects occlude people. In this paper, a novel 3D people positioning and tracking system is presented, which shows itself robust to both possible occlusion sources: static scene objects and other people. The system holds on a set oí múltiple cameras with partially overlapped fields of view. Moving regions are segmented independently in each camera stream by means oí a new background modeling strategy based on Gabor filters. People detection is carried out on these segmentations through a template-based correlation strategy. Detected people are tracked independently in each camera view by means oí a graph-based matching strategy, which estimates the best correspondences between consecutive people segmentations. Finally, 3D tracking and positioning of people is achieved by geometrical consistency analysis over the tracked 2D candidates, using head position (instead of object centroids) to increase robustness to foreground occlusions.

- by Carlos Roberto del Blanco and +1
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- Background modeling, People Tracking, Indoor Environment, Field of View

A ground-level semantic map is obtained by a mobile robot equipped with an omnidirectional camera, differential GPS and a laser range finder. The mobile robot uses a virtual sensor for building detection (based on omnidirectional images) to compute the ground-level semantic map, which indicates the probability of the cells being occupied by the wall of a building. These wall estimates from a ground perspective are then matched with edges detected in an aerial image. The result is used to direct a region-and boundary-based segmentation algorithm for building detection in the aerial image. This approach addresses two difficulties simultaneously: 1) the range limitation of mobile robot sensors and 2) the difficulty of detecting buildings in monocular aerial images. With the suggested method building outlines can be detected faster than the mobile robot can explore the area by itself, giving the robot an ability to "see" around corners. At the same time, the approach can compensate for the absence of elevation data in segmentation of aerial images. Our experiments demonstrate that ground-level semantic information (wall estimates) allows to focus the segmentation of the aerial image to find buildings and produce a ground-level semantic map that covers a larger area than can be built using the onboard sensors.

Secondary elements such as barriers, sidewalks, and diaphragms may increase the load carrying capacity of girder bridges. This in turn affects reliability. The objective of this study is to evaluate the potential benefit of secondary elements on the system reliability of girder bridges, if these elements are designed with the structural system to participate resisting vehicular live loads. Simple span,

- by Andrzej Nowak
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- Engineering, Civil Engineering, Finite element method, Finite Element

A UWB positioning system which performs NLOS identification and TOA-based location estimation is described. For NLOS identification, we consider both a simple variance test, and a more complex non-parametric identification test. The ranging technique is based on TOA estimation, where the nodes can adopt a two-way ranging scheme in the absence of a common clock. From the NLOS identification and range estimation steps, an approximate MLE technique is employed for the node positioning.

- by Zafer Sahinoglu
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- Positioning System, Personal Area Network

Purpose: To evaluate an infrared (IR) marker-based positioning system in patients receiving conformal radiotherapy for prostate cancer. Methods and Materials: During 553 treatments, the ability of the IR system to automatically position the isocenter was recorded. Setup errors were measured by means of orthogonal verification films and compared to conventional positioning (using skin drawings and lasers) in 184 treatments. Results: The standard deviation of anteroposterior (AP) and lateral setup errors was significantly reduced with IR marker positioning compared to conventional: 2 vs. 4.8 mm AP (p < 0.01) and 1.6 vs. 3.5 mm laterally (p < 0.01). Longitudinally, the difference was not significant (3.5 vs. 3.0 mm). Systematic errors were on the average smaller AP and laterally for the IR method: 4.1 vs. 7.8 mm AP (p ‫؍‬ 0.01) and 3.1 vs. 5.6 mm lateral (p ‫؍‬ 0.07). Longitudinally, the IR system resulted in somewhat larger systematic errors: 5.0 vs. 3.4 mm for conventional positioning (p ‫؍‬ 0.03). The use of an off-line correction protocol, based on the average deviation measured over the first four fractions, allowed virtual elimination of systematic errors. Inability of the IR system to correctly locate the markers, leading to an executional failure, occurred in 21% of 553 fractions. Conclusion: IR marker-assisted patient positioning significantly improves setup accuracy along the AP and lateral axes. Executional failures need to be reduced.

- by Vincent Vinh-Hung
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- Prostate Cancer, Standard Deviation, Measurement Error, Skin

Satellite survey techniques have become commonplace for several applications such as surveying, environmental positioning, and navigation. The possibility of using this technique is strongly dependent on the possibility of receiving data from at least four satellites, as the accuracy is dependent on both the number of visible satellites and on their relative positions in the sky. From a theoretical standpoint, the Global Positioning System (GPS) constellation of satellites was designed to guarantee the continuous visibility of a minimum of four satellites worldwide, but this was based on the major approximation of considering the earth as an ellipsoid. The presence of natural (such as mountains) and anthropic (such as buildings) obstacles reduce sky visibility, in some cases significantly, thereby reducing the position accuracy or the possibility of determining a position (in the case of less than four satellites). The evolution of satellite positioning technologies will result in the possibility that, in the near future, many constellations can be used to determine the position of a receiver. Additionally, the Glonass constellation will be improved, and the new Galileo constellation will be deployed. Starting from digital elevation models (DEM), orbits (broadcast or precise), and the Keplerian parameters of new constellations, an open-source software has been realized with the aim of performing more accurate planning and simulations of the skyplot (the map of the visible satellites) in a point or region for a defined window of time. The software, developed in the C++ language, permits the simulation of the current constellation and the simulation of future scenarios by considering the interoperability between NAVSTAR-GPS, GLONASS, Galileo, COMPASS, and other systems. The simulation, conducted using DEM, permits the definition of a more correct obstacle map for each point. Of course, the DEM is more detailed and accurate, resulting in a more precise obstacle map and thus a more precise simulation (DEMs derived from Lidar data can even be used to account for the blockage caused by buildings). This paper begins with an introduction concerning the approach used to determine the skyplot and the obstacle map derived from a DEM, continues by explaining the logical architecture of the software and then presents simulation results in different conditions (with or without the DEM, using different constellations, and considering either one point or a regional analysis).

- by Luca La Via and +1
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- Software Development, Geomatic Engineering, Digital Elevation Model, Positioning System

In Augmented Reality (AR), see-through Head Mounted Displays (HMDs) superimpose virtual 3D objects over the real world. They have the potential to enhance a user's perception and his interaction with the real world. However, many AR applications will not be accepted until we can accurately align virtual objects in the real world. One step to achieve better registration is to improve the tracking system. This paper surveys the requirements for and feasibility of a combination of an inertial tracking system and a vision based positioning system implemented on a parallel SIMD linear processor array.

- by Pieter P Jonker
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- Augmented Reality, Ubicomp, Head Mounted Display, Tracking system

The stress inversion method is developed to find a stress field which satisfies the equation of equilibrium for a body in a state of plane stress. When one stress-strain relation is known and data on the strain distribution on the body and traction along the boundary are provided, the method solves a well-posed problem, which is a linear boundary value problem for Airy's stress function, with the governing equation being the Poisson equation and the boundary conditions being of the Neumann type. The stress inversion method is applied to the Global Positioning System (GPS) array data of the Japanese Islands. The stress increment distribution, which is associated with the displacement increment measured by the GPS array, is computed, and it is found that the distribution is not uniform over the islands and that some regions have a relatively large increment. The elasticity inversion method is developed as an alternative to the stress inversion method; it is based on the assumption of linear elastic deformation with unknown elastic moduli and does not need boundary traction data, which are usually difficult to measure. This method is applied to the GPS array data of a small region in Japan to which the stress inversion method is not applicable. To cite this article: M. Hori et al., C. R. Mecanique 336 (2008). Résumé Méthode d'inversion des contraintes et analyse des données GPS. La méthode d'inversion est développée pour trouver un champ de contraintes satisfaisant les équations d'équilibre pour un corps en situation de contrainte plane. La relation entre contrainte et déformation étant connue et les données de distribution de déformation sur le corps et de traction sur le bord étant fournies, la méthode résout un problème bien posé, qui consiste en un problème aux limites linéaire pour la fonction de contrainte d'Airy, comprenant l'équation de Poisson et des conditions aux limites de type Neumann. La méthode d'inversion est appliquée aux données GPS (Global Positioning System) concernant les îles japonaises. Les incréments de contraintes associés aux incréments de déplacements mesurés par le système GPS sont calculés, et l'on trouve que leur distribution n'est pas uniforme sur les îles, certaines régions présentant un incrément relativement grand. La méthode d'inversion élastique est développée comme alternative à la méthode d'inversion des contraintes ; elle est fondée sur l'hypothèse d'une déformation linéaire élastique avec des coefficients d'élasticité inconnus, et ne requiert pas de données concernant les tractions au bord, généralement difficilement mesurables. La méthode est appliquée aux données GPS d'une petite région du Japon pour laquelle la méthode d'inversion des contraintes n'est pas utilisable. Pour citer cet article : M. Hori et al., C. R. Mecanique 336 (2008).

- by Muneo Hori
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- Mechanical Engineering, Geophysics, Dynamical Systems, Modeling

In this paper we address the problem of building an effi-cient database management system that allows querying for similar images. This system, which supports image-based queries on a database of photographs taken around the campus, helps... more

- by Abhishek Gupta
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- Data Structure, Image Retrieval, DATABASE MANAGEMENT SYSTEM, Nearest Neighbor

This paper presents two novel six-axis magnetic-levitation (maglev) stages capable of nanoscale positioning. These stages have very simple and compact structures, which is advantageous to meet the demanding positioning requirements of next-generation nanomanipulation and nanomanufacturing. Six-axis motion generation is accomplished by the minimum number of actuators and sensors. The first-generation maglev stage, namely the -stage, is capable of generating translation of 300 m and demonstrates position resolution better than 2 nm root-mean-square (rms). The second-generation maglev stage, namely the Y-stage, is capable of positioning at a resolution better than 3 nm rms over a planar travel range of 5 mm × 5 mm. A novel actuation scheme was developed for the compact structure of this stage that enables six-axis force generation with just three permanent-magnet pieces. This paper focuses on the design and precision construction of the actuator units, the moving platens, and the stationary base plates. The performance of the two precision positioners is compared in terms of their positioning and load-carrying capabilities and ease of manufacture. Control system design for the two positioners is discussed and an experimental plant transfer function model is presented for the Y-stage. The superiority of the developed instruments is also demonstrated over other prevailing precision positioning systems in terms of the travel range, resolution, and dynamic range. The potential applications of the maglev positioners include semiconductor manufacturing, microfabrication and assembly, nanoscale profiling, and nanoindentation.

- by Shobhit Verma
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- Engineering, Technology, Semiconductor Manufacturing, Motion control

Technology acceptance of conventional Information and Communication technologies (ICT) devices is extensively researched within the last twenty years. However, comparably small knowledge is prevalent with respect to ubiquitous ICT in the living environment. Furthermore, there is nearly no data about user acceptance's dependency of integrated technologies on varying domestic spaces and how acceptance varies regarding user diversity. This study explores the acceptance of home-integrated ICT (hands-free equipment, camera, positioning system). In different domestic spaces (living room, bedroom, bathroom) acceptance for integrated technology was assessed, using qualitative as well as quantitative methods. Results show that users' acceptance differs considerably depending on the room type (acceptance is the highest in the living and the lowest in the bathroom). Moreover, the most disliked technology for home monitoring are camera-based systems, followed by the positioning system and the microphone. Also, there was a significant interacting effect of room type and technology: While none of these technologies is accepted for the bathroom, the living room is less sensitive to their presence with the microphone as the most accepted technology. User diversity does not play a major role hinting at generic acceptance patterns regarding ICT integrated in home environments.

The prevailing traffic speed at any section of a roadway affects the quality of traffic at the time. Whereas excessive speeds affect the severity of road traffic accidents, crawling speeds in the urban environment is also indicative of congestion. One of the key elements in speed management planning is the functional classification of roads by speed. For example, 30km/h has been designated for residential areas and 60km/h and above for major arterial roads. Nowadays, efficient vehicle monitoring can be achieved by integrating Global Positioning System (GPS) derived traffic data such as vehicle speed and direction of traffic flow into a Geographical Information System (GIS) environment. This GPS-GIS integrated system provides real-time meaningful location and status of the vehicles in the network. The system has been used to show the second-to-second positional changes in speed and directions of vehicles travelling in Kumasi, the second largest city in Ghana. Using the geographic components in a dataset and visualizing the results in a map provided a clearer picture of the traffic-state of every route in the network. The GPS has clearly indicated the road sections where speeds are unacceptable and driver behaviour is affected giving transport planners the option to choose the desired speed management technique to improve the traffic system.

- by Francis Afukaar
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- Urban Environment, Traffic Flow, Real Time, Road Traffic Accident

Modern autonomous vehicles are using more than one method for performing the positioning task. The most common positioning methods for indoor vehicles are odometry for relative positioning and triangulation .for absolute positioning. In many cases a KaIman filter is required to merge the data from the positioning systems and determines the vehicle position based on error analysis of the measurements and calculation procedures. A Kalman filter is particularly advantageous for "onthe-fly" positioning, which is performed while the vehicle is in motion. This paper presents the implementation of a Kalman filter in "ROBI" -an AGV for material handling in a manufacturing environment. The performance of the filter in estimating the position of the AGV and the effect of motion parameters (speed, path curvature, beacon layout etc.) on filter accuracy are shown.

- by S. Shoval
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- Engineering, Kalman Filter, Mathematical Sciences, Error Analysis

Although Thailand is not so prone to flooding compared to other countries in the Southeast Asia region, the country is usually faced with flooding problems every year with increasing severity attributed to climate change, including global warming. Many structural measures have been developed to overcome this problem. However, it is realized that structural measures have failed to prevent flooding completely due to unprecedented and unpredictable flooding events. Some flood protection structures, such as levees tend to increase the flood hazard levels with possible breach due to over-stressing resulting in increased damage. Under the circumstances, nonstructural measures are explored more towards sustainable mitigation. Flood hazard mapping through modelling, which helps analyse a variety of possible scenarios, has been the focus of this study. Nan municipality area in Nan province, Thailand, was selected for the study considering the severity of the past occurrences.

- by Somchit Amnatsan
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- Remote Sensing, Climate Change, Southeast Asia, Global Warming

The ExacTrac X-Ray 6D image-guided radiotherapy (IGRT) system will be described and its performance evaluated. The system is mainly an integration of 2 subsystems: (1) an infrared (IR)-based optical positioning system (ExacTrac) and (2) a radiographic kV x-ray imaging system (X-Ray 6D). The infrared system consists of 2 IR cameras, which are used to monitor reflective body markers placed on the patient's skin to assist in patient initial setup, and an IR reflective reference star, which is attached to the treatment couch and can assist in couch movement with spatial resolution to better than 0.3 mm. The radiographic kV devices consist of 2 oblique x-ray imagers to obtain high-quality radiographs for patient position verification and adjustment. The position verification is made by fusing the radiographs with the simulation CT images using either 3 degree-of-freedom (3D) or 6 degree-of-freedom (6D) fusion algorithms. The position adjustment is performed using the infrared system ...

- by Stephen Tenn
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- Radiosurgery, X-ray imaging, Performance Evaluation, X Rays

- by Daniele Mortari
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- Positioning System

During Mars Exploration Rover (MER) surface operations, the scientific data gathered by the in situ instrument suite has been invaluable with respect to the discovery of a significant water history at Meridiani Planum and the hint of water processes at work in Gusev Crater. Specifically, the ability to perform precision manipulation from a mobile platform (i.e., mobile manipulation) has been a critical part of the successful operation of Spirit and Opportunity rovers. As such, this paper describes the MER Instrument Positioning System that allows the in situ instruments to operate and collect their important science data using a robust, dexterous robotic arm combined with visual target selection and autonomous software functions.

- by Lori Shiraishi
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- Aerospace, Robot Arm, Scientific Data, Mars Exploration Rover Spirit

Summary: The LaCoste & Romberg gravity meter S124b and its associated system environment were installed and tested in conjunction with a strap-down gravity meter system (SAGS) of the Bayerische Akademie der Wissenschaften in Munich on a Cessna Grand Caravan of the DLR in Oberpfaffenhofen. This report describes the design and instrumentation of the aerogravimetry system, it documents the installation on

- by Uwe Meyer and +1
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- Inertial Navigation System, Data Processing, Positioning System

Knowledge management is becoming increasingly important as organizations realize that continuous competitive advantage depends on effective management of their vast and various knowledge assets. In order to improve knowledge management, CoPs (Communities of Practice) are used as powerful tools. By operating CoPs internally and externally, they have made improvements like increased core competency, induced innovation learning, enhanced working efficiency and promoted responsiveness. In order to run CoPs successfully, the evaluation of CoP is also crucial. CoP operators need to understand the current position systemically and determine the currently practiced activities. In order to do this, they need visible and quantifiable metrics for measurement. After deciding the current status of CoP, new objectives and strategies for their improvement are provided. In this paper, we intend to assess the condition of CoPs indirectly, not to measure the efficiency of CoP directly. This research provides a holistic, systematic, and comprehensive framework with maturity stages for navigating CoPs, and provides a road map for moving from immature, inconsistent activities to mature, disciplined approaches aligned to strategic business imperatives.

- by Euiho Suh
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- Computer Science, Knowledge Management, Competitive advantage, Maturity Model

This is the final paper in a four-part series examining the fundamental question, “What does the word height really mean?” The creation of this series was motivated by the National Geodetic Survey’s (NGS) embarking on a height modernization program as a result of which NGS will publish measured ellipsoid heights and computed Helmert orthometric heights for vertical bench marks. Practicing surveyors will therefore encounter Helmert orthometric heights computed from Global Positioning System (GPS) ellipsoid heights and geoid heights determined from geoid models as their published vertical control coordinate, rather than adjusted orthometric heights determined by spirit leveling. It is our goal to explain the meanings of these terms in hopes of eliminating confusion and preventing mistakes that may arise over this change. The first paper in the series reviewed reference ellipsoids and mean sea level datums. The second paper reviewed the physics of heights culminating in a simple develo...

- by Daniel Roman
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- Best practice, Positioning System, Mean Sea Level

It is known that satellite radiolocalization was born in the military environment and was originally conceived for defense purposes. Nevertheless, the commercial explosion (dated to 20 years ago) of global positioning system (GPS) in the civil market (automotive, tourism, etc.) significantly changed the original perspectives of this technology. Another big change is expected when other global navigation satellite systems (GNSSs) such as the European Galileo or the Chinese COMPASS become operational and commercial. In fact, modern GNSSs are conceived principally for the civil market (at the opposite of GPS, whose civil employment is given as a sort of “kind gift,” with lower performance than that one granted to military users). The scope of this paper is to provide readers with a clear focus about the potentialities of current and forthcoming GNSSs and associated technologies in a renewed mass-market perspective. The paper also opens a window to the future of radiolocalization technology beyond GPS and GNSS, dealing with the role of digital signal processing and software-defined radio (SDR) in next-generation navigation systems and with the seamless integration of satellite-based navigation with other technologies in order to provide reliable position information also in hostile environments.

- by Carles Fernández-Prades and +1
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- Biomedical Engineering, Signal Processing, Digital Signal Processing, Inertial navigation

Our objective is to review recent advances in ionospheric and thermospheric modeling that aim at supporting space weather services. The emphasis is placed on achievements of European research groups involved in the COST Action 724. Ionospheric and thermospheric modeling on time scales ranging from a few minutes to several days is fundamental for predicting space weather effects on the Earth's ionosphere and thermosphere. Space weather affects telecommunications, navigation and positioning systems, radars, and technology in space. We start with an overview of the physical effects of space weather on the upper atmosphere and on systems operating at this regime. Recent research on drivers and development of proxies applied to support space weather modeling efforts are presented, with emphasis on solar radiation indices, solar wind drivers and ionospheric indices. The models are discussed in groups corresponding to the physical effects they are dealing with, i.e. bottomside ionospheric effects, trans-ionospheric effects, neutral density and scale height variations, and spectacular space weather effects such as auroral emissions. Another group of models dealing with global circulation are presented here to demonstrate 3D modeling of the space environment. Where possible we present results concerning comparison of the models' performance belonging to the same group. Finally we give an overview of European systems providing products for the specification and forecasting of space weather effects on the upper atmosphere, which have implemented operational versions of several ionospheric and thermospheric models. A. Belehaki ( )

- by A. Belehaki
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- Forecasting, Performance, Ionosphere, Space Weather

ltra-wideband (UWB) radio is a fast emerging technology with uniquely attractive features inviting major advances in wireless communications, networking, radar, imaging, and positioning systems. By its rulemaking proposal in 2002, the Federal Communications Commission (FCC) in the United States essentially unleashed huge "new bandwidth'' (3.6-10.1 GHz) at the noise floor, where UWB radios overlaying coexistent RF systems can operate using low-power ultra-short information bearing pulses. With similar regulatory processes currently under way in many countries worldwide, industry, government agencies, and academic institutions responded to this FCC ruling with rapidly growing research efforts targeting a host of exciting UWB applications: short-range very high-speed broadband access to the Internet, covert communication links, localization at centimeter-level accuracy, high-resolution ground-penetrating radar, through-wall imaging, precision navigation and asset tracking, just to name a few. This tutorial focuses on UWB wireless communications at the physical layer. It overviews the state-of-the-art in channel modeling, transmitters, and receivers of UWB radios, and outlines research directions and challenges to be overcome. As signal processing expertise is expected to have major impact in research and development of UWB systems, emphasis is placed on DSP aspects.

The paper addresses the general problem of estimating the position of an underwater target carrying an acoustic emitter by measuring the times of arrival (TOAs) of the acoustic signals at a set of surface buoys equipped with submerged hydrophones and GPS receivers. Examples of underwater targets of interest include AUVs (Autonomous Underwater Vehicles) and ROVs (Remotely Operated Vehicles) as well as manned submersibles, divers, and even marine animals. When compared with classical systems, the class of underwater acoustic positioning systems considered in this paper is far more versatile and portable and the costs of operation are greatly reduced. This justifies the increasing interest that such systems have received over the past few years, both from a theoretical and practical standpoint. Research and development in this area have progressed to the point where a commercial product made its appearance in the market: the so-called GIB (GPS Intelligent Buoys). However, much work remains to be done towards the development of operational systems capable of yielding adequate performance in the presence of multi-path effects and acoustic outliers. The paper gives a brief overview of this area of research and discusses theoretical and practical issues that arise in the development and operation of acoustic positioning systems at sea.

The Philippine Reference System of 1992 (PRS92) is a network of geodetic control points established by Global Navigation Satellite System (GNSS) that became the standard reference system for all surveying and mapping activities of the archipelagic nation in 1993. Since then however, the PRS92 has remained largely confined at the realm of local geodesists and mapping specialists. It was only recently that PRS92 gained its much-needed attention due to the increased support from the government and improved access to satellite-based positioning systems technologies among stakeholders. In 2008, a collaborative research and development project was undertaken by the National Mapping and Resource Information Authority (NAMRIA) and the University of the Philippines (UP) intended to support its full implementation. This paper summarizes the key findings and recommendations of the research project. The key issues tackled by the PRS92 research included: i. the state and condition current geodetic network, ii. The validation of global geopotential models for the development of a Philippine geoid model, iii. the determination of relationship between GNSS and astrogeodetic azimuth observations in support of survey practice iv. the transformation of previous and local coordinates applied by cadastral systems to PRS92 grid coordinates. The research finding eventually precipitated a set of recommendations to improve, in an integrated manner, the policies, design, planning and implementation of the various aspects of surveys of mapping with PRS92 as the single reference frame. Part of the recommendations included standards, specifications, guidelines, manuals and information dissemination materials to foster the use of the new reference system and ensure its sustainability in the future. This paper also identified various research topics for further collaboration among concerned parties.

The design and the initial realization of control on an experimental in-door unmanned autonomous quadrotor helicopter is presented. This is a hierarchical embedded modelbased control scheme that is built upon the concept of backstepping, and is applied on an electric motor-driven quadrotor UAV hardware that is equipped with an embedded on-board computer, inertial sensor unit, as well as facilities that make it suitable to be involved in an in-door positioning system, and wireless digital communication network. This realization forms an important step in the development process of a more advanced realization of an UAV suitable for practical applications; it aims clarification of the control principles, acquiring experience in solving control tasks, and getting skills for the development of further realizations.

- by Béla Lantos
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- Automation & COntrol, Digital Communication, Electric Motor, Vehicle dynamic control

The high time resolution of ultra-wideband (UWB) signals facilitates very precise position estimation in many scenarios, which makes a variety applications possible. This paper reviews the problem of position estimation in UWB systems, beginning with an overview of the basic structure of UWB signals and their positioning applications. This overview is followed by a discussion of various position estimation techniques, with an emphasis on time-based approaches, which are particularly suitable for UWB positioning systems. Practical issues arising in UWB signal design and hardware implementation are also discussed.

- by Serdar Gezici
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- Biomedical Engineering, Information Theory, Parameter estimation, Impulse Radio

This article is a review of Global Navigation Satellite Systems (GNSS) for space scientists who are interested in how GNSS signals and observables can be used to understand ionospheric dynamics and, conversely, how ionospheric dynamics affect the operational capabilities of GNSS receivers. The most common form of GNSS is the Global Positioning System (GPS); we will first review its operating principles and then present a discussion of errors, of which ionospheric propagation is the most significant. Methods and systems for mitigating errors will be introduced, along with a discussion of modernization plans for GPS and for entirely new systems such as Galileo. In the second half of this article the effects of the ionosphere on GPS signals will be examined in more detail, particularly ionospheric propagation, leading to a discussion of the relation of TEC to ranging errors. Next, the subject of scintillations will also be introduced and connected to the presence and scale sizes of irregularities. Scintillations will be examined as spatial and temporal structures. The method of measuring scintillation pattern drift and ionospheric velocity will be discussed. We conclude by examining ionospheric effects on GPS at midlatitudes. (P.M. Kintner), bml22@ cornell.edu (B.M. Ledvina). www.elsevier.com/locate/asr Advances in Space Research 35 (2005) 788-811

- by Brent Ledvina
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- Mechanical Engineering, Aerospace Engineering, Space, GPS

Identifying locations of nodes in wireless sensor networks (WSNs) is critical to both network operations and most application level tasks. Sensor nodes equipped with geographical positioning system (GPS) devices are aware of their locations at a precision level of few meters. However, installing GPS devices on a large number of sensor nodes not only is expensive but also affects the form factor of these nodes. Moreover, GPS-based localization is not applicable in the indoor environments such as buildings. There exists an extensive body of research literature that aims at obtaining absolute locations as well as relative spatial locations of nodes in a WSN without requiring specialized hardware at large scale. The typical approach consists of employing only a limited number of anchor nodes that are aware of their own locations, and then trying to infer locations of non-anchor nodes using graph-theoretic, geometric, statistical, optimization, and machine learning techniques. Thus, the literature represents a very rich ensemble of algorithmic techniques applicable to low power, highly distributed nodes with resource-optimal computations. In this chapter we take a close look at the algorithmic aspects of various important localization techniques for WSNs.

- by md sajal
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- Machine Learning, Low Power, Wireless Sensor, Large Scale

Rajesh Tiwari, Ph.D, is research associate at School of Electrical and Electronic Engineering, Newcastle University, UK. He has background in ionospheric research and monitoring its effect on GNSS applications. He also works in GPS... more

In this paper we present an approach to teaching an introductory course in electrical and computer engineering to freshmen engineering students. The primary distinguishing characteristics of our approach include: providing information in an experiential context or "teaching-in-context"; focusing on "black-box"-based hierarchical decomposition as an approach to understanding complex systems; and using piece-wise linear models for nonlinear elements as a way to develop intuition and understanding about the workings of circuits. The experiential context is provided by having students carry out a series of laboratory exercises involving an exciting real-world electronic system. To date, we have developed laboratory exercises around a programmable robot and a Global Positioning System receiver. The greatest challenges in teaching an intellectually substantive course to entering freshmen are their lack, on average, of the mathematics and physics background that is taken for granted in most electrical and computer engineering courses. In this paper we demonstrate that by appropriate choice of material and presentation methods this challenge can be overcome.

Signals from Global Positioning System (GPS) satellites at the horizon or at low elevations are often excluded from a GPS solution because they experience considerable ionospheric delays and multipath effects. Their exclusion can degrade the overall satellite geometry for the calculations, resulting in greater errors; an effect known as the Dilution of Precision (DOP). In contrast, signals from high elevation satellites experience less ionospheric delays and multipath effects. The aim is to find a balance in the choice of elevation mask, to reduce the propagation delays and multipath whilst maintaining good satellite geometry, and to use tomography to correct for the ionosphere and thus improve single-frequency GPS timing accuracy. GPS data, collected from a global network of dual-frequency GPS receivers, have been used to produce four GPS timing solutions, each with a different ionospheric compensation technique. One solution uses a 4D tomographic algorithm, Multi-Instrument Data Analysis System (MIDAS), to compensate for the ionospheric delay. Maps of ionospheric electron density are produced and used to correct the single-frequency pseudorange observations. This method is compared to a dual-frequency solution and two other single-frequency solutions: one does not include any ionospheric compensation and the other uses the broadcast Klobuchar model. Data from the solar maximum year 2002 and October 2003 have been investigated to display results when the ionospheric delays are large and variable. The study focuses on Europe and results are produced for the chosen test site, VILL (Villafranca, Spain). The effects of excluding all of the GPS satellites below various elevation masks, ranging from 5°to 40°, on timing solutions for fixed (static) and mobile (moving) situations are presented. The greatest timing accuracies when using the fixed GPS receiver technique are obtained by using a 40°mask, rather than a 5°mask. The mobile GPS timing solutions are most accurate when satellites at lower elevations continue to be included: using a mask between 10°and 20°. MIDAS offers the most accurate and least variable single-frequency timing solution and accuracies to within 10 ns are achieved for fixed GPS receiver situations. Future improvements are anticipated by combining both GPS and Galileo data towards computing a timing solution.

- by Julian Rose
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- Mechanical Engineering, Aerospace Engineering, Data Analysis, Space

This paper reviews the theoretical motivation for the leap second in the context of the historical evolution of time measurement. The periodic insertion of a leap second step into the scale of Coordinated Universal Time (UTC) necessitates frequent changes in complex timekeeping systems and is currently the subject of discussion in working groups of various international scienti c organizations. UTC is an atomic time scale that agrees in rate with International Atomic Time (TAI), but differs by an integral number of seconds, and is the basis of civil time. In contrast, Universal Time (UT1) is an astronomical time scale de ned by the Earth's rotation and is used in celestial navigation. UTC is presently maintained to within 0.9 s of UT1. As the needs of celestial navigation that depend on UT1 can now be met by satellite systems, such as the Global Positioning System (GPS), options for revising the de nition of UTC and the possible role of leap seconds in the future are considered.

- by Daniel McCarthy
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- Metrologia, Global position ing system, Positioning System

The research reported here investigated the reliability of the patient positioning procedure used to evaluate the upper cervical region by practitioners of the Pettibon Technique and sought to establish the range of error of measurement for mensuration. Thirty-eight subjects completed the study which included taking two series of both an anterior to posterior nasium as well as lateral cervical radiographs. The second series of x-rays were taken from one-half to 4 hours after the initial radiographs. While there were no intermediate chiropractic adjustments provided, the use of a simulated adjustment was performed.The collected data indicates that the reliability, as represented by the standard error measurement, is approximately one-half a degree for the upper angle measurement and two-thirds of a degree for the lower angle measurement. In both cases, the measurement error estimate is less than the one degree claimed by the author of the method tested.

- by Dr. Dennis Woggon and +1
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- Engineering, Studies, X Rays, Measurement Error

AbstractÐThe currently adopted approach to reduce observed gravity data for geophysical purposes includes several approximations. These were originally used to reduce computational eort, but have remained standard practice, even though the required computing power is now readily available. In contrast, more precise gravity reductions are routinely employed in physical geodesy. The dierence between simple Bouguer gravity anomalies derived using the geophysical and geodetic approaches can reach several tens of m mm sec À2 . The geodetic reductions include a more accurate calculation of normal gravity as a function of latitude, and a free air correction that accounts for the non-sphericity of the ®gure of the Earth. Also important, especially given the advent of Global Positioning System coordination of gravity surveys, is the need to ensure that the correct vertical and horizontal coordinate systems are used for the gravity reduction procedure. Errors associated with the use of non-geocentric horizontal coordinates and ellipsoidal heights are signi®cant when compared with the accuracy of an individual gravity measurement. A generalised gravity reduction program and a coordinate transformation program are presented which can be employed to reduce geophysical data in a geodetic manner. # 1998 Elsevier Science Ltd

- by Mike Dentith
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- Engineering, Earth Sciences, Geodesy, Geophysics

Location-aware computing is a form of context-aware mobile computing, that refers to the ability of providing users with services that depend on their position. Locating the user terminal, often said positioning, is essential in this form of computing. To this aim, several technologies exist, ranging from personal area networking, to indoor, outdoor and up to geographic area systems. Developers of location-aware software applications have to face with a number of design choices, that typically depend on the chosen technology.

- by Massimo Ficco
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- Location Aware Computing, Positioning System

Hip implant is an orthopedic procedure which the hip joint is replaced by prosthetic or artificial implant in order to replace arthritic or dysfunctional joint surface. The process is also known as hip arthroplasty. However, the metal-on-metal hips articulation suffers from friction due to the moving metal surface thus, shortening the surviving of the joint. A micro pits formation is therefore used for lubrication purpose, which eventually prolong the lifespan of the hips. This paper will focus on the methods for machining the micro pits in terms of work piece placement, coordination and orientation related to the electrode of electrical discharge machining system for lubrication purpose. A new structure of work piece positioning system would be designed accordingly in order to optimize the machining performance and improve lubrication activities in the hip implant device.

- by Nor Liyana Safura Hashim
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- Biomechanics, BioMEMS, Lubrication, Orthopaedics

This paper proposes a control strategy based on artificial neural networks (ANNs) for a positioning system with a flexible transmission element, taking into account Coulomb friction for both motor and load, and using a variable learning rate for adaptation to parameter changes and accelerate convergence. A control structure consists of a feedforward ANN that approximates the manipulator's inverse dynamical model, an ANN feedback control law, a reference model, and the adaptation process of the ANNs with a variable learning rate. A supervisor that adapts the neural network's learning rate and a rule-based supervisor for online adaptation of the parameters of the reference model are proposed to maintain the stability of the system for large variations of load parameters. Simulation results highlight the performance of the controller to compensate the nonlinear friction terms, particularly Coulomb friction, and flexibility, and its robustness to the load and drive motor inertia parameter changes. Internal stability, which is a potential problem in such a system, is also verified. The controller is suitable for DSP and very large scale integration implementation and can be used to improve static and dynamic performances of electromechanical systems.

- by Pierre Sicard and +1
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- Engineering, Intelligent Control, Adaptive Control, Stability

A robust, accurate positioning system with seamless outdoor and indoor coverage is a highly needed tool for increasing safety in emergency response and military urban operations. It must be lightweight, small, inexpensive, and power... more

- by Peter Händel
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- Distributed Computing, Indoor Positioning, Inertial navigation, Emergency Response

Ultra wideband (UWB) positioning systems are increasingly used in indoor environments since commercial systems can provide 3-D accuracy of a few centimeters. Many applications exist in medicine for UWB positioning which includes tracking personnel, assets, and surgical navigation. We have designed a UWB positioning system with millimeter accuracy. Certain applications, including surgical navigation, have even more stringent accuracy requirements in the sub-millimeter range. Many challenges must be overcome to achieve sub-millimeter accuracy including indoor multipath interference, system clock jitter and drift, local oscillator phase noise, sampling-rate limitations, and phase center error. This paper discusses sub-millimeter accuracy in UWB positioning for medical applications and outlines key challenges faced in achieving it with our UWB positioning system. Solutions to these challenges are also outlined followed by a discussion of future work needed to integrate the entire system.

- by Yazhou Wang
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- Ultra Wideband, Phase Noise, Base station, Positioning System

The geopotential-value approach is utilized in this study to estimate the average offsets of local vertical datums (LVDs) in New Zealand realized in the system of normal-orthometric heights. The LVD offsets are taken relative to the World Height System (WHS). We adopt the geoidal geopotential value W 0 =62,636,856 m 2 s −2 for a definition of WHS. The conversion of heights between different permanent tide systems is taken into consideration. The geopotential-value approach utilizes Molodensky's theory of the normal heights. The normal-orthometric heights at global positioning system (GPS)-leveling points are thus first converted to the normal heights. The normal to normal-orthometric height correction is computed and applied along the leveling lines using the leveling data, and the gravity disturbances are computed approximately from the EGM08 global geopotential model. The numerical study is conducted for 18 LVDs in the North and South Islands of New Zealand. The LVD offsets are estimated from EGM08 to GPS-leveling data. The estimated average LVD offsets vary between 1 cm (Wellington 1953 LVD) and 37 cm (One Tree Point 1964 LVD).

- by Ahmed Abdalla
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- Case Study, New Zealand, Geomatic Engineering, Global position ing system

It is well known that for spaceborne satellite positioning systems such as GPS and Glonass, the accuracy, availability and reliability of the positioning results is heavily dependent on the number and geometric distribution of satellites being tracked. However, in some situations, such as in urban canyons and in deep open-cut mines, the number and geometry of visible satellites may not be sufficient to reliably carry out positioning operations. These problems can be addressed by the inclusion of additional ranging signals transmitted from ground-based "pseudo-satellites" (pseudolites). In this paper the authors present details of both theoretical and experimental investigations into the potential integration of GPS and pseudolite technologies for precise positioning applications. The experiments indicate that, with integrated GPS and pseudolite signals, the accuracy and reliability of position results can be improved compared to GPS-only results.

- by Jinling Wang
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- Geomatics, Positioning System

The widespread availability of devices with multiple wireless interfaces and the abundance of heterogene- ous positioning techniques open new market potentials for Location Based Services (LBSs), even if complicat- ing their development. The paper claims the need for novel middleware supports capable of managing dy- namically retrieved client-side positioning systems in a synergic way and depending on context, i.e., LBS re- quirements, user preferences, device characteristics, and overall system state. To pursue this objective, we have designed and implemented PoSIM, a context- aware middleware for the synergic exploitation and control of heterogeneous positioning systems that faci- litates the development and portability of LBSs. PoSIM is translucent, i.e., it can provide LBS developers with differentiated visibility of data characteristics and con- trol possibilities of available positioning solutions, thus dynamically adapting to application-specific dep- loyment requirements and...

- by Carlo Giannelli
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- Middleware, Dynamic Software Adaptation, User preferences, Dep

In densely populated cities or indoor environments, limited accessibility to satellites and severe multipath effects significantly decrease the accuracy and reliability of satellite-based positioning systems. To meet the needs of "seamless navigation" in these challenging environments, an advanced terrestrial positioning system is under development. A new principle of mobile robot navigation capable of working in a complex unknown landscape (another planet or just on a cross-country terrain) is proposed. The optoelectrical method proposed has a good spatial domain resolution and immunity to multipath, as well as new optical means for "technical vision" realization. Two related problems are solved: creation of a technical vision system for recognition of images of an unfamiliar landscape and determination of the direction to the initial point of the movement trajectory of the mobile transport robot. Issues of principle design and also of functioning and interaction of system units and elements are described. A mathematical apparatus for processing digital information inside the system and for determining the distances and angle measurements in the system proposed is developed. Some important parameters are analytically determined: expected accuracy, functioning speed, range of action, power issues, etc.

India is an important non-breeding ground for migratory waterfowl in the Central Asian Flyway. Millions of birds visit wetlands across the country, yet information on their distribution, abundance, and use of resources is rudimentary at best. Limited information suggests that populations of several species of migratory ducks are declining due to encroachment of wetland habitats largely by agriculture and industry. The development of conservation strategies is stymied by a lack of ecological information on these species. We conducted a preliminary assessment of the home range and habitat use of Ruddy Shelduck Tadorna ferruginea in the northeast Indian state of Assam. Seven Ruddy Shelducks were fitted with solar-powered Global Positioning System (GPS) satellite transmitters, and were tracked on a daily basis during the winter of 2009-2010. Locations from all seven were used to describe habitat use, while locations from four were used to quantify their home range, as the other three had too few locations (< 30) for home range estimation. A Brownian Bridge Movement Model (BBMM), used to estimate home ranges, found that the Ruddy Shelduck had an average core use area (i.e. the contour defining 50% of positions) of 40 km 2 (range = 22-87 km 2 ) and an average home range (95% contour) of 610 km 2 (range = 222-1,550 km 2 ). Resource Selection Functions (RSF), used to Resource utilisation by Ruddy Shelduck in India 183 © Wildfowl & Wetlands Trust Wildfowl (2011) 61: 182-193

- by Tsewang Namgail and +1
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- Resource Selection Function, Solar Power, Resource Selection, Habitat Use

The objective of this study is to evaluate and map soil radionuclides' activity concentrations and environmental outdoor gamma dose rates (terrestrial and cosmic) in Kirklareli, Turkey. The excess lifetime cancer risks are also calculated. Outdoor gamma dose rates were determined in 230 sampling stations and soil samples were taken from 177 locations. The coordinates of the readings were determined by the Global Positioning System (GPS). The outdoor gamma dose rates were determined by Eberline smart portable device (ESP-2) and measurements were taken in air for two minutes at 1 m from the ground. The average outdoor gamma dose rate was 118 AE 34 nGy h À1 . Annual effective gamma dose of Kirklareli was 144 mSv and the excess lifetime cancer risk of 5.0 Â 10 À4 . Soil samples were analyzed by gamma spectroscopy. The average 226 Ra, 238 U, 232 Th, 137 Cs, and 40 K activities were 37 AE 18 Bq kg À1 , 28 AE 13 Bq kg À1 , 40 AE 18 Bq kg À1 , 8 AE 5 Bq kg À1 and 667 AE 281 Bq kg À1 , respectively. The average soil radionuclides' concentrations of Kirklareli were within the worldwide range although some extreme values had been determined. Annual effective gamma doses and the excess lifetime risks of cancer were higher than the world's average.

- by Gursel Karahan
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- Soil, Risk, Turkey, Risk assessment