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Made available in DSpace on 2019-10-06T15:45:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-08-15 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The Ambiguity Dilution of Precision (ADOP) is a well-known scalar measure that can be used to infer the strength of the Global Navigation Satellite System (GNSS) model of the carrier phase ambiguities involved in precise relative GNSS positioning. Odijk and Teunissen (2008a) derived closed-form expressions for single-baseline GNSS models that allow verifying the factors affecting the ambiguity resolution as well as the probability of its correct resolution as integer values. However, this weighted-ionosphere ADOP closed form assumes that the standard deviation of the ionosphere delay is dependent on a function associated with the baseline length. This means that a baseline of the same length at different locations around the world and in different moments in time would have the same standard deviation, which in practice is not true. This becomes even worse in regions like Brazil, where the ionospheric anomalies are more intense and frequent, especially in periods of high solar activity. In this work, a new method for calculating the ionospheric delay standard deviation that considers the ionospheric scintillation S4 index is proposed to improve the closed-form ADOP performance. Experiments with a baseline of 280 m located in Presidente Prudente, Brazil (magnetic latitude of around −13°), were carried out. The results showed that in periods of both weak and strong ionospheric scintillation, the introduction of S4 into the ionospheric delay standard deviation was beneficial for ADOP. The average improvement of the ADOP closed form was of around 72% in the analyzed period of weak scintillation and of 35% in the period of strong scintillation. In addition, the results showed that in periods of strong scintillation, relative positioning accuracy is around 100 times worse, up to 30 m, when compared to periods of weak ionospheric scintillation. São Paulo State University (Unesp) School of Technology and Sciences State University of Maringa (UEM), Maringá São Paulo State University (Unesp) School of Technology and Sciences FAPESP: 2013/06325-9 FAPESP: 2016/24861-3

U ovom radu obrađuje se programiranje tehnoloških objekata za apsolutno i relativno pozicioniranje. Za kontrolu projekta upotrebljava se PLC kontroler S7-1511TF. Koriste se dva servo motora (SIMOTICS S-1FK2) povezana na pretvarače (SINAMICS S210), od kojih je jedan glavni dok se drugi njemu sinkronizira. U prvom dijelu opisana je konfiguracija komponenti projekta u TIA Portal-u te puštanje u rad servo motora. Navedene su karakteristike pojedine komponente projekta. Za komunikaciju se koristi PROFINET mreža koja omogućuje brzu komunikaciju IRT konceptom ispod 1ms. U drugom dijelu prikazani su programski funkcijski blokovi sa njihovim mrežama. Objašnjena je funkcionalnost blokova upravljanja položajem svake mreže i povezanost sa pripadajućim tehnološkim objektom. Za upravljanje i vizualizaciju projekta koristi se HMI sučelje gdje se mogu uključivati pogoni, odabrati se parametri apsolutnog i relativnog pozicioniranja te sinkronizirati drugi uređaj. This project is about programming technology object for absolute and relative positioning. PLC controller S7-1511TF is used for controlling the project. There are also two servo motors (SIMOTICS S-1FK2), connected to the SINAMICS S210 converter. The left servo motor is the master drive and the other (right) slave drive synchronizes to the master. The first section of the paper describes the configuration of components in TIA Portal and commissioning of the servo drives. The communication is established with PROFINET network, which enables fast IRT communication under 1 millisecond. The second part shows program objects with function blocks. The main characteristics and functionality of the control function blocks are listed. For the control and visualization a HMI interface is arranged with the ability to turn on the drives, choose the parameters of absolute and relative positioning and synchronizing the drives.

Ambiguity resolution plays an important role in surveying using Precise Point Positioning (PPP) and relative positioning techniques that require high accuracy. In this study, ambiguity resolution performance of PPP and relative positioning under the unobstructed (with 7° cut-off angle) and constrained environment (with 25° cut-off angle, such as nearby buildings and street-canyons) using final/ultra-rapid orbit and clock products are investigated for different observation time. Seventeen globally distributed stations and six baselines of lengths from 270 km to 2100 km are chosen for conducting PPP and relative positioning, respectively. A 31-day period in January 2018 is chosen for processing using 24-, 12-, 6-, 4-, 2- and 1-h observations. The results indicate that sub-mm to cm levels of improvement in horizontal and vertical coordinate components are generally observed with ambiguity resolution for PPP and relative positioning techniques compared to the float counterparts. Moreover, accuracy degradation of ambiguity resolution compared to float solution is observed generally in the vertical component using the 25° elevation cut-off angle for both techniques. As the observation time increases, the accuracy improvements from ambiguity resolution decrease for each technique. In addition, fixing to the wrong integer ambiguities are generally seen with a short observation time and a 25° elevation cut-off angle for both techniques due to the poor satellite geometry. As far as baseline length in relative technique is concerned, the testing results show that there is no direct relation between baseline length and the accuracy improvement from ambiguity resolution compared to the float solution. The results also reveal that the coordinates obtained from ambiguity resolution does not significantly change in the relative technique using final or ultra-rapid orbit/clock products, whereas the changes in PPP are significant for most of the stations.

Submitted by Caio Henrique Chrisostomo Mendonça (caio.mendonca@unesp.br) on 2019-08-16T18:04:19Z No. of bitstreams: 1 Dissertação_CaioMendonça.pdf: 3304939 bytes, checksum: 36b1825ef1e90fff7bd8656b3187228e (MD5) Rejected by Claudia Adriana Spindola null (claudia@fct.unesp.br), reason: Solicitamos que realize correções na submissão seguindo as orientações abaixo: - Acrescentar a seguinte expressão do financiador nos agradecimentos : O presente trabalho foi realizado com apoio da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Código de Financiamento 001 - Também selecionar no campo financiador: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil Agradecemos a compreensão. on 2019-08-16T19:12:19Z (GMT) Submitted by Caio Henrique Chrisostomo Mendonça (caio.mendonca@unesp.br) on 2019-08-19T15:18:24Z No. of bitstreams: 1 Dissertação_CaioMendonça2.pdf: 3282606 bytes, checksum: 9e5b405260d2a7816059502bdf948cfd (MD5) Approved for entry into archive by Claudia Adriana Spindola null (claudia@fct.unesp.br) on 2019-08-19T18:18:16Z (GMT) No. of bitstreams: 1 mendonça_chc_me_prud.pdf: 3282606 bytes, checksum: 9e5b405260d2a7816059502bdf948cfd (MD5) Made available in DSpace on 2019-08-19T18:18:16Z (GMT). No. of bitstreams: 1 mendonça_chc_me_prud.pdf: 3282606 bytes, checksum: 9e5b405260d2a7816059502bdf948cfd (MD5) Previous issue date: 2019-04-26 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) A observável fase da onda portadora é utilizada quando se deseja obter alta acurácia no posicionamento por sistemas globais de navegação por satélite. Mas, esta observável pode sofrer perdas de ciclos durante o rastreamento do sinal. Uma perda de ciclo é uma descontinuidade de um número inteiro de ciclos na fase da onda portadora, causada por uma perda temporária de rastreamento do sinal pelo receptor. Assim, as perdas de ciclos devem ser detectadas e corrigidas para que se obtenha posicionamento acurado. Diversos métodos foram desenvolvidos com esse objetivo. Algo que também vem sendo amplamente estudado é a detecção das perdas de ciclos nos novos sinais GPS. O advento da terceira frequência disponibilizada a partir da modernização do GPS também deve ser explorado. Na presente pesquisa buscou-se estudar os diferentes métodos de detecção e correção de perdas de ciclos e implementar o mais adequado para o posicionamento de alta acurácia no Brasil. Foram selecionadas duas metodologias para fim de detecção e correção, sendo a primeira baseada no método das triplas diferenças (TD) clássico e a segunda baseada no método de sequência de combinações lineares. Além disso, foi proposta uma terceira metodologia para melhoria do método das TD. Foram realizados dois experimentos, sendo o primeiro realizado com dados simulados e o segundo com dados reais em período de alta atividade ionosférica, e para ambos os casos foram considerados dois cenários: linha de base curta e linha de base longa. Para dados simulados, em linha de base curta, o método TD clássico, o método TD proposto e o método das sequências de combinações lineares apresentaram 100%, 99,91% e 100% de acerto na detecção, resultando em 99,91%, 99,88% e 100% de acerto na correção das perdas de ciclos, respectivamente. Para linha de base longa, com dados simulados, obteve-se 31,37%, 63,79% e 100% de acerto na detecção, resultando em 49,45%, 95,32% e 100% de acerto na correção das perdas de ciclos quando utilizado o método TD clássico, o método TD proposto e o método das sequências de combinações lineares, respectivamente. No segundo experimento, conduzido com dados reais foi possível avaliar somente a melhoria no posicionamento, sendo esta para linha de base curta, de 81,71%, 67,08% e 10,79% para o método TD clássico, o método TD proposto e o método das sequências de combinações lineares, respectivamente. Em linha de base longa, após correção, o método TD clássico obteve piora de 12,18%, o método TD proposto proporcionou melhoria de 40,63%, enquanto o método das combinações lineares não apresentou melhoria. Carrier phase observable are used in high accuracy positioning by global navigation satellite systems. However, the carrier phase measurement may suffer cycle slips during signal tracking. A cycle slip is a discontinuity of an integer number of cycles in the phase observable, caused by a temporary loss of lock in the receiver carrier tracking loop. Thus, cycle slips must be detected and corrected in order to obtain accurate positioning. Several methods were developed for this purpose. Something that has also been studied is the detection of cycle slip in the new GPS signals. The advent of the third frequency available from the GPS modernization. Should be explored in the context of cycle slip detection and correction. In the present research the different cycle slip detection and correction methods were studied and t the most suitable for the high accuracy positioning in Brazil was implemented. Two methodologies were selected for the purpose of this research, the first one based on the classical triple difference (TD) method and the second based on the linear combination sequence method. In addition, a third methodology was proposed to improve the TD method. Two experiments were performed, the first one being carried out with simulated data and the second with real data in the period of high ionospheric activity, and for both cases two scenarios were considered: short baseline and long baseline. For simulated short baseline data, the classical TD method, the proposed TD method and the linear combination sequence method presented 100%, 99.91% and 100% accuracy in the detection, resulting in 99.91%, 99.88% and 100% accuracy in the correction of cycle slips, respectively. For the simulated long baseline data, 31.37%, 63.79% and 100% of detection accuracy were obtained, resulting in 49.45%, 95.32% and 100% accuracy in the correction of cycles slips when using the classical TD method, the proposed TD method and the linear combination sequence method, respectively. In the second experiment, conducted with real data, it was possible to evaluate only the improvement in the positioning, being this for short baseline, of 81.71%, 67.08% and 10.79% for the classical TD method, the proposed TD method and linear combination sequence method, respectively. In the long baseline, after correction, the classical TD method obtained a worsening of 12.18%, the proposed TD method provided an improvement of 40.63%, whereas the linear combination sequence method could not show evaluated. FAPESP: 2016/26000-5

This thesis explores the problem of computing a position map for co-located mobile devices. The positioning should happen in a scalable manner without requiring specialized hardware and without requiring specialized infrastructure (except basic Wi-Fi or cellular access). At events like meetings, talks, or conferences, a position map can aid spontaneous communication among users based on their relative position in two ways. First, it enables users to choose message recipients based on their relative position, which also enables the position-based distribution of documents. Second, it enables senders to attach their position to messages, which can facilitate interaction between speaker and audience in a lecture hall and enables the collection of feedback based on users’ location. In this thesis, we present Sonoloc, a mobile app and system that, by relying on acoustic signals, allows a set of commodity smart devices to determine their relative positions. Sonoloc can position any number of devices within acoustic range with a constant number of acoustic signals emitted by a subset of devices. Our experimental evaluation with up to 115 devices in real rooms shows that – despite substantial background noise – the system can locate devices with an accuracy of tens of centimeters using no more than 15 acoustic signals. Diese Dissertation befasst sich mit dem Problem, eine Positionskarte von sich am gleichen Ort befindenden mobilen Geräten zu berechnen. Dies soll skalierbar, ohne Verwendung von spezialisierter Hardware oder Infrastruktur (ausgenommen einfache WLAN- oder Mobilfunkzugang) erfolgen. Bei Veranstaltungen wie Meetings, Diskussionen oder Konferenzen kann eine Positionskarte die Benutzer bei spontaner Kommunikation mithilfe der relativen Positionen in zweierlei Hinsicht unterstützen. Erstens ermöglicht sie den Benutzern, die Empfänger von Nachrichten aufgrund deren Position zu wählen, was auch eine positionsabhängige Verteilung von Unterlagen erlaubt. Zweitens ermöglicht sie den Sendern, ihre Position in die Nachrichten zu integrieren, was eine Interaktion zwischen Referent und Zuhörer in einem Hörsaal und die Sammlung von positionsabhängigen Rückmeldungen erlaubt. In dieser Dissertation stellen wir die Mobile-App und das System Sonoloc vor, das mithilfe von Tonsignalen erlaubt, die relative Position handelsüblicher, intelligenter Geräte zu bestimmen. Sonoloc kann eine beliebige Zahl von Geräten innerhalb des Hörbereichs durch eine gleichbleibende Zahl von Tonsignalen, die von einer Teilmenge der Geräte gesendet werden, lokalisieren. Unsere experimentelle Analyse mit bis zu 115 Geräten in echten Räumen zeigt, dass das System trotz signifikanter Hintergrundgeräusche unter Verwendung von bis zu 15 Tonsignalen mit einer Genauigkeit von wenigen Dezimetern Geräte lokalisieren kann. This work was supported in part by the European Research Council (ERC Synergy imPACT 610150), the German Science Foundation (DFG CRC 1223), the Japan Society for the Promotion of Science (Grant-in-Aid for Scientific Research (A), KAKENHI Grant Number 16H01735), and the National Science Foundation (NSF Awards CNS 1526635 and CNS 1314857).

During the last decade Global Positioning System (GPS) Continuous Operating Reference Stations networks have become a new important data source for meteorology. This has dramatically improved the ability to remotely sense the atmosphere under the influence of severe mesoscale and synoptic systems. The zenith tropospheric delay (ZTD) is one of the atmospheric variables continuously observed, and its horizontal variations, the horizontal tropospheric gradients, are routinely computed nowadays within the dual-frequency GPS processing, but their interpretation and relationship with the weather is still an open question. The purpose of this paper is to contribute in this direction by studying the effect that Hurricane Harvey had on the spatial and temporal behavior of the ZTDs and gradients, when it reached Texas coast, during 18–31 August 2017. The results show that ZTD time series present a clear and rapid increase larger than 10 cm in a few hours when the hurricane reached the area. Gradients behaviors show that the hurricane also produced significant changes on them, since the magnitude and predominant directions before and after the hurricane arrived are completely different. Noticeably, the gradient vectors before the landing are consistently related to the horizontal winds and pressure fields. In this manuscript we demonstrate that the ZTD gradients can show a consistent signature under severe weather events, strongly suggesting their potential application for short-term weather forecasting., Facultad de Ciencias Astronómicas y Geofísicas

Na kakovost določitve položaja točke z GNSS vpliva več dejavnikov. Eden od njih je troposferska refrakcija, ki predstavlja zakasnitev signala GNSS v troposferi. Za odstranitev vpliva so do sedaj razvili številne modele troposferske refrakcije, v katerih je glavni problem modeliranje vsebnosti vodne pare v ozračju, saj se ta nenehno časovno in prostorsko spreminja. V najnižji plasti troposfere se vodna para lahko kondenzira v meglo. Cilj diplomske naloge je ugotoviti, ali ta meteorološki pojav znatno vpliva na kakovost relativne določitve položaja z GNSS. S tem namenom smo v programu Leica Infinity obdelali 10-dnevna opazovanja GNSS s treh stalno delujočih postaj, ki se nahajajo v Ljubljanski kotlini, kjer se megla pogosto pojavlja. Končni rezultat so bile koordinate dveh novih točk, ki smo jih določili z metodo radialne izmere. Vpliv megle smo ocenili na osnovi primerjave izračunanih koordinatnih razlik za posamezno točko. Rezultati kažejo, da prisotnost megle bistveno ne vpliva na kakovost relativno določenega položaja z GNSS. The quality of determining the point position with GNSS is influenced by several factors one of them is a tropospheric refraction, which represents the delay of the GNSS signal in the troposphere. To remove the influence, a number of tropospheric refractive models have been developed. Their main problem is modeling the content of the water vapor in the atmosphere, since it changes constantly in time and space. In the lowest layer of the troposphere, water vapor can condense into the fog. The aim of the graduation thesis is to determine whether this meteorological phenomenon significantly affects the quality of the relative positioning with GNSS. For this purpose, we analyzed 10-day observations of GNSS from three constantly operating stations located in the Ljubljana basin, where fog often occurs, using the Leica Infinity program. The final result was the coordinates of two new points, which were determined by the radial processing. The influence of the fog was estimated basing on the comparison of the calculated coordinate differences for each point. The results show that the fog presence does not significantly affect the quality of the relative positioning with GNSS.

In this paper, we investigate a relative positioning technique using the vehicle-to-vehicle communication signal. Specifically, we use the delay and Doppler information provided by the channel impulse response. Since the geometry of the vehicles has a direct impact on the delay and Doppler frequency, it is possible to deduce the relative positions of the vehicles. This particular relationship can be exploited by using prolate spheroidal coordinates. By doing an algebraic analysis in this coordinate system closed form solutions for delay and Doppler frequency can be derived. The delay and Doppler information is then used to determine the relative position similar to using the bearing and distance to a lighthouse in marine navigation or distance measuring equipment (DME) and VHF omnidirectional radio range (VOR) in aeronautical navigation.

Use of a frequency-division multiple access strategy causes Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) receiving equipment to experience both inter-frequency phase bias (IFPB) and inter-frequency code bias (IFCB). While IFPB can be calibrated using a linear model, there is no general model for IFCB calibration, which causes great difficulty in GLONASS ambiguity resolution over long baselines; most current GLONASS ambiguity resolution research is confined to short baselines. In this paper, based on a single-differencing between-receivers (SDBR) model, a wide-lane phase combination-based approach is proposed to fix the GLONASS ambiguities over long baselines. External precise ionospheric products are introduced to eliminate the ionospheric delay. To mitigate the effect of the residual ionospheric delays, we fix the relative wide-lane ambiguity using the Hatch–Melbourne–Wubbena (HMW) combination. The results show that 96% and 55% of the wide-lane round-off residuals are within 0.2 cycles for the Global Positioning System (GPS) and GLONASS, respectively, if the traditional HMW method is used. The method proposed here for GLONASS can improve these percentages significantly, reaching up to 95.5%. The root mean square (RMS) position errors are 1.43, 1.06 and 4.32 mm for GPS in the north, east and up directions, respectively. When GLONASS with ambiguity fixing is added, the corresponding RMS values are reduced significantly to 1.26, 1.02 and 3.87 mm, respectively.

This paper proposes a control strategy for a mobile robot for precision agriculture. The controller allows autonomous navigation through corridors formed by plants or fruit vines and olive trees. Furthermore, a rotation strategy based on odometer is proposed. The controller uses an algorithm for estimating the states of the system based on information from a laser sensor, which is enhanced by an Extended Kalman Filter which considers the model of the robot-environment interaction. The controller also incorporates the use of odometer sensors for automation of rotation between the end and beginning of plant corridors. The method has been tested in a real environment using a Pionner3AT (outdoor) robot navigating over a typical olive grove of the INTA - EEA San Juan (Pocito, San Juan, Argentina). Fil: Penizzotto Bacha, Franco Victor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Juan. Instituto de Automática; Argentina Fil: Slawiñski, Emanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Juan. Instituto de Automática; Argentina Fil: Mut, Vicente Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Juan. Instituto de Automática; Argentina

In the field of Global Satellite Navigation System (GNSS), modern mass-market receivers are able to provide raw measurements, thus representing a valuable resource for the design of new navigation algorithms. Among these devices, a considerable amount of smartphones allows to gather such measurements before they are processed to compute the positioning solution. In parallel, they provide natively ubiquitous connectivity within low-latency cellular networks. This framework has enabled the implementation of novel paradigms of positioning including networked GNSS positioning. Navigation algorithms exploiting relative positioning have been widely investigated in the last years and many kinds of shareable data have been integrated within collaborative approaches (e.g. GNSS navigation data, relative distance, relative heading). The present work investigates geometrical impairments in the computation of pairwise ranges (i.e. Inter-Agent Range) through the exchange of GNSS-only measurements between a pair of GNSS receivers in short baseline scenario. Although Inter-Agent Range technique acts similarly to code-pseudorange single differences, it exploits the angle obtained from the joint observation of a common satellite by two collaborating receivers. A statistical characterization of the output measurements is provided along with the evaluation of optimal and suboptimal geometrical conditions. A mathematical model for collaborative systems is formulated and compared with a collection of realistic simulation results for the validation. Raw and corrected measurements were compared, thus highlighting a remarkable advantage of the latter in terms of biases. The results confirm the suitability of the presented model for the optimization of collaborative and differential GNSS applications.

Large safety distances between consecutive trains limit the flexibility and capacity of rail traffic. The introduction of automatic distance control between trains has the potential to reduce the safety distances. This requires an accurate and reliable distance estimation. In this paper, we therefore evaluate the performance of a relative localization system that tightly integrates the global satellite navigation system (GNSS) measurements and a map of the track network. The tight integration reduces the absolute train position to a 1-D value that describes the position on a track. The relative position is then calculated by subtracting two 1-D positions. In an empirical evaluation the tightly integrated system is compared to a loosely integrated system and a cooperative approach based solely on GNSS measurements. The cooperative approach uses GNSS pseudorange and range rate double differences, to determine the baseline between two antennas. For the loosely integrated system first the 3-D train position is estimated in an extended Kalman filter (EKF). In a second step, this position is matched to the map to obtain the position on the track. The relative position root-mean-square error (RMSE) of the different approaches is determined with a 167 km long data set, measured on a diesel train over the duration of 6 hours. The data set is divided into open sky, suburban and forest environments. For each of these environments, six different antenna distances are evaluated. The results show that the tightly and loosely integrated systems have a considerable smaller RMSE than the cooperative approach. The difference in the average performance of the two map based approaches is negligible. An advantage of the tight integration can be seen only under poor satellite visibility conditions that were encountered only sporadic during the measurements.

The European Geostationary Navigation Overlay Service (EGNOS) thanks to geostationary satellites covers an area of whole Europe, including Baltic and North Sea. It allows to fix the coordinates of object position with typical absolute accuracy of 1,5 m. Previous research have shown that relative accuracy is usually higher than absolute one [Nowak A., 2010; Nowak A., 2011], so probably it could be possible to use EGNOS to determine direction in space. The research described in the paper concerned relative accuracy of three homogeneous EGNOS receivers, in context of the ability to determine the ship’s hull spatial orientation. Theoretical basis, the process of the experiment and the results of recorded data analysis were described. The research were conducted in the summer of 2014. Three homogenous Leica Viva series receivers were used. They were configured to receive a differential messages of the EGNOS system. Recorded data were analyzed in context of fixes relative accuracy. On the basis of achieved results, a conclusion about the possibility of construction the measurement system for the automatic determination of the ship’s hull spatial orientation angles in real time was drawn. The further research directions were pointed out, too.

Upravljanje položajem sinkronim strojem sa stalnim magnetima realizirano je korištenjem frekvencijskog pretvarača SINAMICS S120 i programilabilnog logičkog kontrolera SIMATIC S7-1500. Nakon kratkog osvrta na korištene komponente upravljanja i opisa osnovnih principa rada istih, opisana je realizacija apsolutnog, relativnog i pozicioniranja prema unaprijed definiranoj sekvenci korištenjem frekvencijskog pretvarača, što uključuje parametrizaciju, izradu programskih blokova, te puštanje u pogon unutar Siemensovog programskog paketa Starter. Nakon konfiguracije pretvarača, kao nadređena upravljačka jedinica dodan je PLC. Opisano je uspostavljanje PROFINET komunikacije, korišteni telegram za komunikaciju pretvarača i PLC-a, te izrada upravljačkog programa i simuliranog vizualizacijskog sučelja (HMI) korištenjem programskog paketa TIA portal. Position control of synchronous motor with permament magnets is implemented using frequency converter SINAMICS S120 and programable logic controller SIMATIC S7-1500. After short overwiev of used components and description of their basic working principles, implementation of the absolute, relative and positioning with predefined trajectory using frequency converter is described. That includes parametrisation, traversking blocks programming and drive commissioning using Starter software. After configuration of the frequency converter, PLC is added as a control unit of the drive. PROFINET communication establishment is described, together with used communication telegram, PLC programming and programming of the simulated human machine interface using TIA portal software.

Trafikolyckor är ett problem i dagens samhälle och nya lösningar inom intelligenta transportsystem (ITS) efterfrågas. En lösning är fordon-till-fordon kommunikation (V2V), där säkrare trafik kan uppnås genom att fordon sänder relevant trafikdata till omgivande trafik. I denna rapport undersöktes och utvecklades metoder för en följdetekteringsalgoritm inom V2V kommunikation. Uppdraget var att hitta en lösning för följdetektering med GPS och radiokommunikation med FM-RDS, där hänsyn togs till tidsfördröjning. Algoritmer utvecklades i en simuleringsmiljö, för att sedan implementeras i en egenkonstruerad prototyp för mätning i trafik. För effektivt utnyttjande av FM-RDS-paket komprimerades den sända positionen, för att sedan rekonstrueras vid mottagarsidan.Resultaten av simuleringarna och trafikmätningarna visade att det var möjligt att detektera om ett fordon följde efter ett annat i trafiken, med hjälp av GPS-positionering och kommunikation genom FM-RDS med tidsfördröjning av mottagna paket. Vid högre tidsfördröjningar så presterade algoritmen sämre, dock finns det potential till förbättring. Förslag på förbättring av rekonstruktionsfunktionen samt algoritmen behandlas i denna rapport. Traffic accidents are a problem in today’s society and new solutions regarding intelligent transportation systems (ITS) are being requested. One solution to such is vehicle-to-vehicle communication (V2V), where safer traffic can be achieved by vehicles transmitting relevant traffic information to surrounding vehicles. In this report, we researched and developed methods for a follow-detection algorithm for V2V communication. The task was to find a solution for follow-detection by using GPS and FM-RDS, with regards to time delay. An algorithm was developed in a simulated environment, to then be implemented in a prototype for measuring traffic. For efficient usage of FM-RDS packets, the transmitted position was compressed and then decompressed at the receiving side. The results of the simulations and traffic tests indicated that it was possible to detect if a vehicle followed another in traffic, by using GPS positioning and FM-RDS with time delay. The accuracy of the algorithm degraded at higher time delays, however there is potential for improvements. Suggestions for improvements of the reconstruction function and the algorithm are discussed in this report.

In recent years, due to the increase in providers of orbit and clock corrections of satellites for data evaluation in real-time Ephemerides, Web and post-processing the method of Precise Point Positioning (PPP) using measurements of Global Navigation Satellite System (GNSS) and Web-based online positioning services have become widespread. Owing to some advantages, such as work-duration and cost-effectiveness, many of users have implemented PPP method instead of the traditional relative positioning method for several applications. On GNSS applications the quality of satellite ephemerides products used for data evaluation is a significant factor that affects the results in post-processing solutions either applying relative or PPP methods on analyses. These products, classified as ultra-rapid, rapid and final orbits, are regularly provided by several national and international organizations to the users. In this paper, the accuracy of PPP method has been studied comparing the outcomes from various online Web services using different software and satellite ephemerides products. For this purpose, three test points were established on a place with completely free satellite visibility (AC01) and on the other two places with partially (YC01) and vastly (KC01) prevention of satellite signals near and within a forest area at Campus of Davutpaşa of the Yildiz Technical University of Istanbul. At these stations, static observations have been conducted with a time span of 6 hours on 4th May 2015. The dataset collected using Topcon HiperPro receiver, a receiver for GPS and GLONASS data, was evaluated manually by means of the Bernese v5.2 (BSW) and GIPSY-OASIS v6.3 (Gipsy) scientific software. Moreover, the GNSS data were also proceeded using six different Web-based online services (AUSPOS, OPUS, CSRS-PPP, APPS, GAPS, Trimble-RTX) with ultra-rapid, rapid and final satellite ephemerides products. For the station with free satellite visibility (AC01), the analyses of outcomes indicate a coordinate accuracy of 1 cm for Web-based and manual data processing. That suggests relative good quality of orbit and clock corrections of satellites used by online data processing services for PPP. Furthermore, for station with partially (YC01) prevention of satellite signals, manual solutions have approximately 1 cm coordinate accuracies for n, e and u components. Moreover, when we compare the results among Web-based services, AUSPOS in relative solution and Trimble-RTX in PPP solution provides the best results. Here, one must emphasize that Trimble-RTX is a Web-based processing service for GNSS data (GPS, GLONASS, BeiDou, and QZSS) and operates an own global network of approximately 100 stations around the world for this purpose. For station with vastly (KC01) prevention of satellite signals, the best solutions were provided by APPS and CSRS-PPP using PPP approach among the Web-based services. Here, Trimble-RTX could not produce any solution. These results could demonstrate the benefit of multi constellation of GNSS in the areas with limited satellite visibility because of increasing of the number of measurements. RESUMEN En los años recientes, debido al incremento de operadores satelitales de corrección de órbita y tiempo para la de información en tiempo real y de postproceso, se ha generalizado el método de posicionamiento preciso (PPP, del inglés Precise Point Positioning) que utiliza medidas del Sistema Global de Navegación por Satélite (GNSS, del inglés Global Navigation Satellite System) y servicios web de posicionamiento en línea. Debido a ventajas como el tiempo de ejecución y la relación costo-efectividad, muchos de los usuarios han implementado el método PPP en varias aplicaciones antes que el método tradicional de posicionamiento relativo. En las aplicaciones GNSS, la calidad de los productos de efemérides satelitales utilizados para la evaluación de información es un factor significante que afecta los resultados en las soluciones postproceso sea con la aplicación de métodos relativos o PPP en los análisis. Estos productos, clasificados como ultrarrápidos, rápidos y de órbita final, los proveen a los usuarios diferentes organizaciones nacionales e internacionales. En este artículo se estudia la exactitud del método PPP en comparación con los resultados de varios servicios web que utilizan diferentes productos de software y de efemérides satelitales. Con este objetivo se establecieron tres puntos de evaluación: el primero en un lugar con completa visibilidad satelital (AC01) y los otros dos con parcial (YC01) y reducida (KC01) señal satelital, en los alrededores y al interior de una zona boscosa del campus de Davutpaşa, en la Universidad Técnica Yildiz de Estambul. En las estaciones se llevaron a cabo observaciones estáticas con intervalos de seis horas el 4 de mayo de 2015. La información se recolectó con el programa Topcon HiperPro, un receptor de GPS y GLONASS (sistema GNSS desarrollado por la Unión Soviética), y se evaluó manualmente con el software científico Bernese v5.2 (BSW) y GIPSY-OASIS v6.3 (GIPSY). Además, la información también se procesón con seis servicios web en línea (AUSPOS, OPUS, CSRS-PPP, APPS, GAPS, Trimble-RTX) con productos de efemérides ultrarrápidas, rápidas y finales. Para la estación con completa visibilidad satelital (AC01), el análisis de los resultados indican una precisión coordinada de 1 cm en los procesamientos web y manual. Esto sugiere una buena calidad de las correcciones satelitales de órbita y tiempo usadas por los servicios de procesamiento de información en línea con el método PPP. Además, para la estación con señal parcial (YC01), las soluciones manuales tienen aproximadamente 1cm de coordinación en la precisión para los componentes Norte y Este. Luego, cuando se comparan los resultados entre los servicios web, los mejores resultados fueron de AUSPOS en soluciones relativas y Trimble RTX en el método PPP. Es importante recalcar que Trimble RTX es un servicio de procesamiento web para información GNSS (GPS, GLONASS, BeiDou y QZSS) y opera una red global propia de unas 100 estaciones en el mundo para este fin. Para la estación con una reducida señal satelital (KC01), las mejores soluciones fueron ofrecidas por APPS y CSRS-PPP con el método PPP entre los servicios web. En este caso, Trimble-RTX no puede producir ninguna solución. Estos resultados demuestran los beneficios de la multiconstelación GNSS en las áreas con visibilidad satelital limitada gracias al incremento del número de medidas.

Future driver assistance systems will rely on accurate, reliable and continuous knowledge on the position of other road participants, including pedestrians, bicycles and other vehicles. The usual approach to tackle this requirement is to use on-board ranging sensors inside the vehicle. Radar, laser scanners or vision-based systems are able to detect objects in their line-of-sight. In contrast to these non-cooperative ranging sensors, cooperative approaches follow a strategy in which other road participants actively support the estimation of the relative position. The limitations of on-board ranging sensors regarding their detection range and angle of view and the facility of blockage can be approached by using a cooperative approach based on vehicle-to-vehicle communication. The fusion of both, cooperative and non-cooperative strategies, seems to offer the largest benefits regarding accuracy, availability and robustness. This survey offers the reader a comprehensive review on different techniques for vehicle relative positioning. The reader will learn the important performance indicators when it comes to relative positioning of vehicles, the different technologies that are both commercially available and currently under research, their expected performance and their intrinsic limitations. Moreover, the latest research in the area of vision-based systems for vehicle detection, as well as the latest work on GNSS-based vehicle localization and vehicular communication for relative positioning of vehicles, are reviewed. The survey also includes the research work on the fusion of cooperative and non-cooperative approaches to increase the reliability and the availability.

In recent years, due to the increase in providers of orbit and clock corrections of satellites for data evaluation in real-time and post-processing the method of Precise Point Positioning (PPP) using measurements of Global Navigation Satellite System (GNSS) and Web-based online positioning services have become widespread. Owing to some advantages, such as work-duration and cost-effectiveness, many of users have implemented PPP method instead of the traditional relative positioning method for several applications. On GNSS applications the quality of satellite ephemerides products used for data evaluation is a significant factor that affects the results in post-processing solutions either applying relative or PPP methods on analyses. These products, classified as ultra-rapid, rapid and final orbits, are regularly provided by several national and international organizations to the users. In this paper, the accuracy of PPP method has been studied comparing the outcomes from various online Web services using different software and satellite ephemerides products. For this purpose, three test points were established in a place with completely free satellite visibility (AC01) and on the other two places with partially (YC01) and vastly (KC01) prevention of satellite signals near and within a forest area at Campus of Davutpaşa of the Yildiz Technical University in Istanbul. At these stations, static observations have been conducted with a time span of 6 hours on 4th May 2015. The dataset collected using Topcon HiperPro receiver, a receiver for GPS and GLONASS data, was evaluated manually by means of the Bernese v5.2 (BSW) and GIPSY-OASIS v6.3 (Gipsy) scientific software. Moreover, the GNSS data were also proceeded using six different Web-based online services (AUSPOS, OPUS, CSRS-PPP, APPS, GAPS, Trimble-RTX) with ultra-rapid, rapid and final satellite ephemerides products. For the station with free satellite visibility (AC01), the analyses of outcomes indicate a coordinate accuracy of 1 cm for Web-based and manual data processing. That suggests relative good quality of orbit and clock corrections of satellites used by online data processing services for PPP. Furthermore, for station with partially (YC01) prevention of satellite signals, manual solutions have approximately 1 cm coordinate accuracies for n, e and u components. Moreover, when we compare the results among Web-based services, AUSPOS in relative solution and TrimbleRTX in PPP solution provides the best results. Here, one must emphasize that Trimble-RTX is a Web-based processing service for GNSS data (GPS, GLONASS, BeiDou, and QZSS) and operates an own global network of approximately 100 stations around the world for this purpose. For station with vastly (KC01) prevention of satellite signals, the best solutions were provided by APPS and CSRS-PPP using PPP approach among the Web-based services. Here, Trimble-RTX could not produce any solution. These results could demonstrate the benefit of multi-constellation of GNSS in the areas with limited satellite visibility because of increasing of the number of measurements. Comparación de precisión del método de Posicionamiento Preciso frente al posicionamiento relativo a través de diferentes productos de efemérides satelitales cerca y bajo un ambiente boscosoResumenEn los años recientes, debido al incremento de operadores satelitales de corrección de órbita y tiempo para la evaluación de información en tiempo real y de postproceso, se ha generalizado el método de posicionamiento preciso (PPP, del inglés Precise Point Positioning) que utiliza medidas del Sistema Global de Navegación por Satélite (GNSS, del inglés Global Navigation Satellite System) y servicios web de posicionamiento en línea. Debido a ventajas como el tiempo de ejecución y la relación costo-efectividad, muchos de los usuarios han implementado el método PPP en varias aplicaciones antes que el método tradicional de posicionamiento relativo. En las aplicaciones GNSS, la calidad de los productos de efemérides satelitales utilizados para la evaluación de información es un factor significante que afecta los resultados en las soluciones postproceso sea con la aplicación de métodos relativos o PPP en los análisis. Estos productos, clasificados como ultrarrápidos, rápidos y de órbita final, los proveen a los usuarios diferentes organizaciones nacionales e internacionales. En este artículo se estudia la exactitud del método PPP en comparación con los resultados de varios servicios web que utilizan diferentes productos de software y de efemérides satelitales. Con este objetivo se establecieron tres puntos de evaluación: el primero en un lugar con completa visibilidad satelital (AC01) y los otros dos con parcial (YC01) y reducida (KC01) señal satelital, en los alrededores y al interior de una zona boscosa del campus de Davutpaşa , en la Universidad Técnica Yildiz de Estambul. En las estaciones se llevaron a cabo observaciones estáticas con intervalos de seis horas el 4 de mayo de 2015. La información se recolectó con el programa Topcon HiperPro, un receptor de GPS y GLONASS (sistema GNSS desarrollado por la Unión Soviética), y se evaluó manualmente con el software científico Bernese v5.2 (BSW) y GIPSY-OASIS v6.3 (GIPSY). Además, la información también se procesón con seis servicios web en línea (AUSPOS, OPUS, CSRS-PPP, APPS, GAPS, Trimble-RTX) con productos de efemérides ultrarrápidas, rápidas y finales. Para la estación con completa visibilidad satelital (AC01), el análisis de los resultados indican una precisión coordinada de 1 cm en los procesamientos web y manual. Esto sugiere una buena calidad de las correcciones satelitales de órbita y tiempo usadas por los servicios de procesamiento de información en línea con el método PPP. Además, para la estación con señal parcial (YC01), las soluciones manuales tienen aproximadamente 1cm de coordinación en la precisión para los componentes Norte y Este. Luego, cuando se comparan los resultados entre los servicios web, los mejores resultados fueron de AUSPOS en soluciones relativas y Trimble RTX en el método PPP. Es importante recalcar que Trimble RTX es un servicio de procesamiento web para información GNSS (GPS, GLONASS, BeiDou y QZSS) y opera una red global propia de unas 100 estaciones en el mundo para este fin. Para la estación con una reducida señal satelital (KC01), las mejores soluciones fueron ofrecidas por APPS y CSRS-PPP con el método PPP entre los servicios web. En este caso, Trimble-RTX no puede producir ninguna solución. Estos resultados demuestran los beneficios de la multiconstelación GNSS en las áreas con visibilidad satelital limitada gracias al incremento del número de medidas.

In this paper we focus on the relative position and orientation estimation between rigid bodies in an anchorless scenario. Several sensor units are installed on the rigid platforms, and the sensor placement on the rigid bodies is known beforehand (i.e., relative locations of the sensors on the rigid body are known). However, the absolute position of the rigid bodies is not known. We show that the relative localization of rigid bodies amounts to the estimation of a rotation matrix and the relative distance between the centroids of the rigid bodies. We measure all the unknown pairwise distances between the sensors, which we use in a constrained least squares estimator. Furthermore, we also allow missing links between the sensors. The simulations support the developed theory.

The Chinese Area Positioning System (CAPS) is a new positioning system developed by the Chinese Academy of Sciences based on the communication satellites in geosynchronous orbit. The CAPS has been regarded as a pilot system to test the new technology for the design, construction and update of the BeiDou Navigation Satellite System (BDS). The system structure of CAPS, including the space, ground control station and user segments, is almost like the traditional Global Navigation Satellite Systems (GNSSs), but with the clock on the ground, the navigation signal in C waveband, and different principles of operation. The major difference is that the CAPS navigation signal is first generated at the ground control station, before being transmitted to the satellite in orbit and finally forwarded by the communication satellite transponder to the user. This design moves the clock from the satellite in orbit to the ground. The clock error can therefore be easily controlled and mitigated to improve the positioning accuracy. This paper will present the performance of CAPS-based relative positioning and velocity estimation as assessed in Beijing, China. The numerical results show that, (1) the accuracies of relative positioning, using only code measurements, are 1.25 and 1.8 m in the horizontal and vertical components, respectively; (2) meanwhile, they are about 2.83 and 3.15 cm in static mode and 6.31 and 10.78 cm in kinematic mode, respectively, when using the carrier-phase measurements with ambiguities fixed; and (3) the accuracy of the velocity estimation is about 0.04 and 0.11 m/s in static and kinematic modes, respectively. These results indicate the potential application of CAPS for high-precision positioning and velocity estimation and the availability of a new navigation mode based on communication satellites.

Two - dimensional localization process of sensor entities is gaining immense research interest,due to its applications not only in the field of Wireless Sensor Network (WSN) or Internet of Things (IoT),but also in disciplines that are radically different than mainstream areas such as health care,food processing,construction,etc. Having knowledge of information about location of origin of data is crucial from point of view of adding relative relevance to that data. However,the embedded system,which is the major base of development for WSN and IoT as well as the taxonomy of node structures,imposes constraints on selection and development of localization scheme. Through this research effort,we will try to model basic localization schemes and evaluate their trade offs between achieved accuracy and expense,energy cost. In the end,few new dimensions to the existing localization problem are also discussed. https://www.ijiert.org/paper-details?paper_id=140715

Forward collision warning systems, lane change assistants, and cooperative adaptive cruise control are examples of safety relevant applications that rely on accurate relative positioning between vehicles. Current solutions estimate the position of an in-front driving vehicle by measuring the distance with a radar sensor, a laser scanner, or a camera system. The perception range of these sensors can be extended by the exchange of GNSS information between the vehicles using an intervehicle communication link. One possibility is to transmit GNSS pseudorange and carrier phase measurements and compute a highly accurate baseline vector that represents the relative position between two vehicles. Solving for the unknown integer ambiguity is specially challenging for low-cost single-frequency receivers. Using the well-known LAMBDA (Least-squares AMBiguity Decorrelation Adjustment) algorithm, in this paper, we present a method for tracking the ambiguity vector solution, which is able to detect and recover from cycle slips and cope with changing satellite constellations. In several test runs performed in real-world open-sky environments with two vehicles, the performance of the proposed Ambiguity Tracker approach is evaluated. The experiments revealed that it is in fact possible to track the position of another vehicle with subcentimeter accuracy over longer periods of time with low-cost single-frequency receivers.

Dissertação de Mestrado em Engenharia Electrotécnica e de Computadores apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra. Ao longo dos últimos anos, com o advento dos sistemas de transporte inteligentes e sistemas de navegação autónoma, o problema de localização tornou-se um assunto de enorme relevância, cuja solução a comunidade científica têm mostrado crescente interesse e apresentado diversas soluções e métodos. A variedade de abordagens, empregando diversos sensores e métodos é consequência direta da complexidade do tema, muito devido aos ambientes e condições diversas de operação dos veículos. É possível obter bom desempenho com sistemas que recorrem a instrumentação muito dispendiosa e geralmente volumosa. Infelizmente, é impraticável a sua utilização em veículos comuns, uma vez que representariam uma grande percentagem no custo total dos mesmos. Esta dissertação propõe o desenvolvimento e teste de um método de estimação de posição e orientação, recorrendo apenas ao sistema de navegação por satélite (GNSS) e à interação e colaboração entre os diversos agentes na estrutura rodoviária, através da norma de comunicação entre veículos (802.11p). Tem como principal objectivo apresentar uma alternativa de baixo custo (equipamentos e instalação), sem comprometer o processo de estimação da localização. Para tal, propõe-se a utilização de dois receptores GPS por veículo, dispostos longitudinalmente na cobertura de modo a maximizar a distância entre ambos, de forma a calcular o ângulo Y aw e Pitch. Para o cálculo do ângulo de Roll o sistema proposto utiliza informação de um receptor exterior ao veículo, proveniente de outro agente rodoviário, através do sistema de comunicação. De forma a aumentar a resolução das observações de cada antena, o sistema proposto faz uso de métodos de posicionamento relativo (RTK) a dois níveis: a nível local (entre as antenas do veículo), para a determinação dos ângulos de orientação e a nível global (entre o veículos e a rede de estações permanente) de forma a estimar a posição do veículo. Faz ainda parte do sistema proposto um método de filtragem de observações, que através da estimação das baselines entre receptores, é capaz de remover as observações com maior probabilidade de estarem afetadas de erro, evitando que este erro seja propagado à fase de estimação da orientação. Os resultados experimentais obtidos referentes a um percurso de aproximadamente 650 metros, em campo aberto e céu pouco nublado, revelaram-se bastante satisfatórios, tendo-se conseguido erros médios de 7 graus em Y aw e erros menores que 5 graus em Pitch e Roll. Na estimação da posição foram obtidos erros médios na ordem dos 2.5 metros. Over the past few years, with the advent of intelligent transport systems and autonomous navigation systems, the problem of location has become relevant a issue whose solution the scientific community have shown growing interest and presented various solutions and methods. The variety of approaches, using various sensors and methods is a direct consequence of the complexity of the theme, largely due to the various environments and conditions of vehicle operation. It’s possible to obtain good performance with systems using very expensive and often bulky instrumentation. Unfortunately, their use on common vehicles is impractical since it would represent a large percentage of the total cost. This dissertation proposes to develop and test a method of location and pose estimation, using only the global navigation satellite system (GNSS) and the interaction and collaboration among the various agents in road infrastructure through vehicle communication standard (802.11p). Its main purpose is to provide a low cost alternative (equipment and installation), without compromising the process of location estimation. To this end, it proposes the use of two GPS receivers for each vehicle, disposed longitudinally on the cover (to maximize the distance between receivers) in order to estimate the yaw and pitch angle. To estimate the roll angle, the proposed system uses information from a receiver outside the vehicle through the communication system. In order to increase the resolution of observations for each antenna, the system makes use of relative positioning (RTK) at two levels: locally (in the vehicle’s antennas) for determining the pose angles and globally (between the vehicle and a permanent station network) in order to estimate the absolute position of the vehicle. It is also part of the proposed system, a method of observation filtering based on receptor baseline estimation. It is capable of removing the observations more likely to be affected with errors, avoiding this errors to be propagated to the orientation estimation stage. The experimental results obtained on a route of approximately 650 meters, in an open area, proved to be quite satisfactory, having achieved average errors of 7 degrees in Yaw angle and smaller errors than 5 degrees in Pitch and Roll angles. In position estimation, the mean error obtained in the same conditions was about 2.5 meters.

International audience; We propose an approach for future localization systems which is quite different from the Global Navigation Satellite Systems standard. The idea is to think about the localization process in a relative way, i.e. to consider the entities with regard to each other. We aim at designing a relative system in order to simplify the practical aspects (low power because low range, no complex synchronization processes, etc.), but also in order to considerably improve the precision (by using local phase measurements of carriers typically). The main idea is based on the fact that it is often sufficient to have a "local understanding" of the localization and that the knowledge of the "geometry" of the distribution of a set of entities allows us to perform the mission. Furthermore, we know that it is possible to achieve accurate relative measurements between two entities, by using measurements of phases of a carrier for example. We shall thoroughly describe the problem of what could be a precise positioning system not requiring any specific infrastructure, and affordable in terms of technologies as well as low energy consumption. This is made possible by use of mature technologies and by the fact that the proposed radio communication links are carried out at short distances, only between two entities. We suggest using only Doppler-like measurements, similar to a radar approach, but through a single way transmission. It is then possible to know the value of the projection of the difference of the speed vectors of the two entities on the axis which separates them. By using only these measurements, we define a new type of positioning and we also analyze the possibility to go back to an absolute positioning, sometimes made possible by the availability of absolute data, as distances or geographical coordinates of a few terminals. In a second approach, we deal with geometry (the calculation of angles) while introducing measurements relative to a reference terminal. Having studied the feasibility to calculate the various angles, from only Doppler-like measurements of four terminals relatively with the others, we show it is possible to obtain the relative positions of the entities. The problem is however not trivial because numerous symmetries exist. Simulations allow us to provide first validations of these concepts. A third approach, still based on relative measurements between two terminals, consists in using distance measurements. We could envisage for example time of flight measurements between two Ultra Wide Band (UWB) knots. In such a case, the calculations are much easier

Advanced Driver Assistance Systems (ADAS) play an important role in increasing the safety on today’s roads. Forward collision warning systems, lane change assistants or cooperative adaptive cruise control are examples of safety relevant applications that rely on accurate relative positioning between vehicles. Current solutions found in commercial automobiles estimate the position of surrounding vehicles by measuring the distance with RADAR, cameras or IR-sensors. It is envisioned that the advent of inter-car communication will provide on-board relative positioning systems with further information about other vehicles in the surrounding area. While performing research in this field, the need of a proper reference system for testing new approaches originates. In the ideal case, such a reference system would yield the exact and continuous 3D baseline between two vehicles at any time in any circumstance. In this paper we will characterize the use of a laser scanner as a reference system for relative vehicle positioning.

A ionosfera é uma das principais fontes de erro sistemático das observáveis GNSS (Global Navigation Satellite System). Esse erro é diretamente proporcional ao TEC (Total Electron Content- Conteúdo Total de Elétrons), ou seja, à densidade de elétrons presentes na ionosfera ao longo do caminho entre o satélite e a antena receptora. O TEC varia regularmente ao longo do dia, ao longo das estações do ano e também ao longo de ciclos de aproximadamente onze anos. No entanto, além das variações regulares, eventos solares extremos (explosões solares, ejeções coronais de massa, entre outros) podem causar abruptas e significativas mudanças no comportamento do TEC, exercendo grande influência no posicionamento com GNSS, principalmente com receptores de uma freqüência. Neste trabalho realizou-se um estudo da severa tempestade geomagnética iniciada em 29 de Outubro de 2003 (em decorrência de uma ejeção coronal de massa), com ênfase nas suas conseqüências sobre a ionosfera terrestre e o posicionamento relativo com GPS (Global Positioning System) em linhas de base longas na região brasileira. The ionosphere is a major source of systematic error in the GNSS (Global Navigation Satellite System) observable. This error is directly proportional to the TEC (Total Electron Content), or the density of electrons in the ionosphere along the path between the satellite and the receiving antenna. The TEC varies regularly throughout the day, the seasons and also over cycles of about eleven years. However, besides the regular variations, extreme solar events (solar fiares, coronal mass ejections, etc.) can cause abrupt and significant changes in the behavior of TEC, wielding great influence in GNSS positioning, especially with single frequency receivers. A study of severe geomagnetic storm started on 29 October 2003 (due to a coronal mass ejection), with emphasis on their consequences on the terrestrial ionosphere and the relative positioning the region of Brazil was carried out in this paper.

The relative positioning technique plays an essential role in Global Navigation Satellite System (GNSS) surveys. Simultaneous observation at base and rover stations eliminates the majority of error sources thus the quality of a positioning solution can be substantially improved. However, topographic obstruction is still a key issue affecting positioning quality. In this study, an integrated approach for analyzing the impact of topographic obstruction on GNSS relative positioning has been developed. By considering varied satellite geometry according to actual terrain variation, this approach can be used to realistically determine satellite visibility condition for a specific base station with respect to any rover station. Furthermore, a base station quality index (BSQI) is proposed as an explicit indication of the sufficiency in a relative positioning. By incorporating the proposed approach, one can immediately identify an optimal site location for a GNSS base station with subsequent GNSS field survey thus achieved in a more reliable and cost-efficient manner. Técnica de posicionamento relativo tem desempenhado um papel essencial em pesquisas de Sistema de Navegação Global via Satélites (GNSS). Coletando observações simultâneas entre estações base e móvel, uma grande parte das fontes de erro é eliminada; portanto a qualidade de solução do posicionamento pode ser substancialmente melhorada. No entanto, a obstrução topográfica ainda é uma questão-chave que afeta a qualidade de posicionamento. Neste estudo, uma abordagem integrada para analisar o impacto da obstrução topográfica em posicionamento relativo GNSS foi desenvolvida. Esta abordagem considera a geometria variada dos satélites de acordo com variações reais do terreno, e as condições de visibilidade do satélite para uma estação base específica com relação a qualquer estação móvel pode ser realisticamente determinada. Além disso, uma base de índice de qualidade da estação (BSQI) é proposta como uma indicação explícita para sua eficiência em um posicionamento relativo. Conseqüentemente, pode-se identificar imediatamente um local otimizado para uma estação base do GNSS, incorporando a abordagem proposta de antemão, e uma pesquisa de campo GNSS, podendo assim alcançar uma forma mais confiável e de custo-eficiente.