Visible Light Positioning using Received Signal Strength for Industrial Environments

There is a forecast for exceptional digital data traffic growth due to the digitisation of industrial applications using the internet of things. As a result, a great need for high bandwidth and faster transmission data rates for future wireless networks has emerged. One of the considered communication technologies that can assist in satisfying this demand is visible light communications (VLC). VLC is an emerging technology that uses the visible light spectrum by mainly utilising lightemitting diodes (LEDs) for simultaneous indoor lighting and high bandwidth wireless communication. Some of the applications of VLC are to provide high data rate internet in homes, offices, campuses, hospitals, and several other areas. One of these promising areas of application is for industrial wireless communications. The research project will provide a review of VLC applications intended for industrial applications with an emphasis on visible light positioning (VLP). In this research work, a three-dimensional (3D) positioning algorithm for calculating the location of a photodiode (PD) is presented. It solely works on measured powers from different LED sources and does not require any prior knowledge of the receiver’s height unlike other works in the literature. The performance of the proposed VLP algorithm in terms of positioning error is evaluated using two different trilateration algorithms, the Cayley–Menger determinant (CMD) and the Linear Least Squares (LLS) trilateration algorithms. The evaluation considers different scenarios, with and without receiver tilt, and with multipath reflections. Simulation results show that the CMD algorithm is more accurate and outperforms the LLS trilateration positioning algorithm. Furthermore, the proposed method has been experimentally assessed under two different LED configurations, with different degrees of receiver tilt, and in the presence of a fully stocked storage rack to examine the effect of multipath reflections on the performance of VLP systems. It was observed from simulations and experimental investigations that the widely used square LED-configuration results in position ambiguities for 3D systems while a non-lattice layout, such as a star-shaped configuration, is much more accurate. An experimental accuracy with a 3D median error of 10.5 cm was achieved using the CMD algorithm in a 4 m × 4 m × 4.1 m area with a horizontal receiver. Adding receiver tilt of 5◦ and 10◦ increases the median error by an average of 29% and 110%, respectively. The effect of reflections from the i storage rack has also been thoroughly examined using the two mentioned trilateration algorithms and showed to increase the 3D median positioning error by an average of 69% in the experimental testbed for the areas close to the storage rack. These results highlight the degrading effect of multipath reflections on VLP systems and the necessity to consider it when evaluating these systems. As the primary consideration for positioning systems in industrial environments is for mobile robots, the encouraging results in this thesis can be further improved though the use of a sensor fusion method

All over the place localization system

The MAP-i Doctoral Programme in Informatics, of the Universities of Minho, Aveiro and PortoA localização é normalmente obtida utilizando um sistema de navegação baseado num ambiente estruturado. No entanto, estes sistemas não funcionam ou são difíceis de serem implantados em ambientes densos. Assim, considerando que as pessoas se deslocam geralmente a pé, neste trabalho é proposto um Sistema de Navigação Inercial para Pedestres (PINS). Nesta tese são identificadas as principais vantagens e desvantagens dos PINS, bem como, os algoritmos que estão na base destes sistemas. O objetivo é fornecer uma perspectiva abrangente sobre o que é necessário para desenvolver um PINS e quais os problemas encontrados mais frequentemente durante o seu desenvolvimento. São também identificados e comparados os sistemas e tecnologias mais importantes da literatura. Duas unidades de medição inercial foram desenvolvidas, sendo que os sensores inerciais foram combinados com sensores de força para melhorar a detecção das diferentes fases (fase de apoio e fase de balanço) da marcha humana, assim como, para ter uma informação mais precisa sobre a força de contacto. É muito importante que a fase de apoio seja devidamente detectada. Assim três diferentes algoritmos, utilizando diferentes sensores e métodos de fusão sensorial, são explicados e avaliados. A marcha humana representa um padrão que é repetido ao longo do tempo, o qual é aprendido utilizando algoritmos de aprendizagem com base nos dados obtidos pelas diferentes fontes de informação para realizar uma caracterização do passo. Esta caracterização leva a uma melhoria no desempenho do sistema, uma vez que os erros sistemáticos podem ser aprendidos, para depois serem corrigidos em tempo real. Como neste sistema existe mais do que uma fonte de informação, além das técnicas de fusão sensorial, são também aplicadas técnicas de fusão de informação. Depois dos dados serem obtidos com o equipamento desenvolvido, e do passo ser caracterizado com os dados aprendidos, são aplicados os algoritmos que fazem a estimativa do deslocamento. A arquitetura proposta é avaliada em quatro cenários de utilização real, dentro de um edifício, envolvendo diferentes tipos de caminhadas. Esta arquitectura levou a uma melhoria significativa da precisão da estimativa do deslocamento.Nowadays location information is typically obtained using a navigation system based on a structured environment. However, these systems do not work or are very difficult to be deployed in dense environments. Thus, considering that persons are usually on foot, in this work is proposed a Pedestrian Inertial Navigation System (PINS). In this thesis are identified the main advantages/disadvantages about PINS, as well as, the algorithms that are the base of this type of systems. It is provided a good insight about what is necessary to create a PINS and the problems that are encountered during its development. To complement these insights the fundamentals about Human Gait are presented, along with the main sensor and information fusion strategies used in this type of system. Also, the most important systems and technologies are identified and compared. Two inertial measurement units were developed, where the inertial sensors were combined with force sensors to improve the detection of different phases (stance and swing phase) of the human gait, as well as, to have proper information about the contact force. The stance phase is very important to be properly detected, therefore, three different algorithms using different sensors and sensor fusion methods are explained and evaluated. The human gait cycle represents a pattern that is a repeatable over time. Thus, this pattern is learned using machine learning algorithms, which are applied to the data obtained from the different data sources to perform a step characterization. This characterization leads to an improvement on the system’s performance, since the systematic errors can be learned to then be corrected in real-time. Since there is more than one source of information, besides sensor fusion techniques, it was also implemented an information fusion strategy. After collecting the data with the developed hardware and characterize the step according to the learned data, it is demonstrated the developed displacement estimation architecture. The proposed architecture and algorithms are evaluated through four real use case scenarios in a typical indoor environment involving different types of walking paths. This architecture led to a significant improvement on the displacement estimation accuracy.This work is funded by the ERDF (European Regional Development Fund) through the COMPETE Programme and by the Portuguese Government through the FCT (Portuguese Foundation for Science and Technology) within the doctoral grant SFRH/BD/70248/2010

Towards UAV-assisted monitoring of onshore geological CO2 storage site

Scientists all over the world look for solutions to reduce greenhouse gas emissions in an effort to achieve proclaimed emissions reduction targets. An intriguing candidate with the potential to make a substantial contribution to this attempt is carbon capture and storage (CCS). The key advantage of CCS is that it provides the possibility to make a significant impact on the reduction of anthropogenic carbon dioxide (CO2) emissions from power plants and carbon-rich industry processes while maintaining existing fossil fuel energy infrastructure. The technique could therefore be used as a transitional solution until fossil fuels can be eliminated from the energy generation mix, and the energy efficiency of industrial processes as well as appliances and products is further improved. Like other technologies, CCS comes with its risks and rewards. To minimize possible negative impacts on humans as well as on the environment, it is necessary to understand the risks and to address them accordingly. A range of monitoring solutions for geological CO2 storage sites is available. However, a cost-effective solution for the regular observation of atmospheric CO2 concentrations (or tracer concentrations) of large areas above onshore geological CO2 storage sites has yet to be developed. This thesis discusses the use of a helicopter unmanned aerial vehicle (UAV) to fill this gap. The robot platform and its autopilot are designed to cope with ongoing sensor developments in addition to providing safety features necessary for the beyond line-of-sight operation of the UAV. The design focuses on the use of commercial off-the-shelf components for the aerial platform in order to shorten the development time and to reduce costs. The autopilot does neither enforce a specific helicopter model nor defines a set position estimation unit to be used. Access to the control loop enables low-level extensions like obstacle avoidance to be implemented. The developed solution allows the monitoring of an area of approximately 750m2 with one set of batteries in one altitude with a spatial resolution of 2m by 2m. Experiments show that point source leaks of as low as 100kg CO2 per day can be detected and their source located. As opposed to autonomous take-offs of the helicopter UAV, autonomous landings on small dedicated helipads require an accurate localization system. A time difference of arrival (TDOA) based acoustic localization system which is based on planar microphone arrays with at least four microphones is proposed. The system can be embedded into the landing platform and provides the accuracy necessary to land the UAV on a helipad of the size of 1m by 1m. A review of existing TDOA-based approaches is given. Simulations show that the developed approach outperforms its direct competitors for the targeted task. Furthermore, experimental results with the developed UAV confirm the feasibility of the introduced method. The effects of the sensor arrangement onto the quality of the calculated position estimates are also discussed. In order to combine robotic-assisted monitoring solutions and other monitoring strategies (e.g. sensor networks and individual sensors) into a single solution, it is necessary to have a framework which allows next to the measurement data analysis also the management (path changes, robot behavior changes, monitoring of internal robot state) of possibly multiple heterogeneous mobile robotic systems. A modular user interface (UI) framework is proposed which allows robots from different vendors and with various configurations next to individual sensors and sensor networks to be managed from a single application. The software system introduces a strict separation between the robot control software and UIs. UI implementations inside the UI framework can be reused across robot platforms, which can reduce the integration time of new robots significantly. The end user benefits by being able to manage a fleet of robots from various vendors and being able to analyze all the measurement data together in a single solution

Políticas de Copyright de Publicações Científicas em Repositórios Institucionais: O Caso do INESC TEC

A progressiva transformação das práticas científicas, impulsionada pelo desenvolvimento das novas Tecnologias de Informação e Comunicação (TIC), têm possibilitado aumentar o acesso à informação, caminhando gradualmente para uma abertura do ciclo de pesquisa. Isto permitirá resolver a longo prazo uma adversidade que se tem colocado aos investigadores, que passa pela existência de barreiras que limitam as condições de acesso, sejam estas geográficas ou financeiras. Apesar da produção científica ser dominada, maioritariamente, por grandes editoras comerciais, estando sujeita às regras por estas impostas, o Movimento do Acesso Aberto cuja primeira declaração pública, a Declaração de Budapeste (BOAI), é de 2002, vem propor alterações significativas que beneficiam os autores e os leitores. Este Movimento vem a ganhar importância em Portugal desde 2003, com a constituição do primeiro repositório institucional a nível nacional. Os repositórios institucionais surgiram como uma ferramenta de divulgação da produção científica de uma instituição, com o intuito de permitir abrir aos resultados da investigação, quer antes da publicação e do próprio processo de arbitragem (preprint), quer depois (postprint), e, consequentemente, aumentar a visibilidade do trabalho desenvolvido por um investigador e a respetiva instituição. O estudo apresentado, que passou por uma análise das políticas de copyright das publicações científicas mais relevantes do INESC TEC, permitiu não só perceber que as editoras adotam cada vez mais políticas que possibilitam o auto-arquivo das publicações em repositórios institucionais, como também que existe todo um trabalho de sensibilização a percorrer, não só para os investigadores, como para a instituição e toda a sociedade. A produção de um conjunto de recomendações, que passam pela implementação de uma política institucional que incentive o auto-arquivo das publicações desenvolvidas no âmbito institucional no repositório, serve como mote para uma maior valorização da produção científica do INESC TEC.The progressive transformation of scientific practices, driven by the development of new Information and Communication Technologies (ICT), which made it possible to increase access to information, gradually moving towards an opening of the research cycle. This opening makes it possible to resolve, in the long term, the adversity that has been placed on researchers, which involves the existence of barriers that limit access conditions, whether geographical or financial. Although large commercial publishers predominantly dominate scientific production and subject it to the rules imposed by them, the Open Access movement whose first public declaration, the Budapest Declaration (BOAI), was in 2002, proposes significant changes that benefit the authors and the readers. This Movement has gained importance in Portugal since 2003, with the constitution of the first institutional repository at the national level. Institutional repositories have emerged as a tool for disseminating the scientific production of an institution to open the results of the research, both before publication and the preprint process and postprint, increase the visibility of work done by an investigator and his or her institution. The present study, which underwent an analysis of the copyright policies of INESC TEC most relevant scientific publications, allowed not only to realize that publishers are increasingly adopting policies that make it possible to self-archive publications in institutional repositories, all the work of raising awareness, not only for researchers but also for the institution and the whole society. The production of a set of recommendations, which go through the implementation of an institutional policy that encourages the self-archiving of the publications developed in the institutional scope in the repository, serves as a motto for a greater appreciation of the scientific production of INESC TEC

Remote Sensing and Geosciences for Archaeology

This book collects more than 20 papers, written by renowned experts and scientists from across the globe, that showcase the state-of-the-art and forefront research in archaeological remote sensing and the use of geoscientific techniques to investigate archaeological records and cultural heritage. Very high resolution satellite images from optical and radar space-borne sensors, airborne multi-spectral images, ground penetrating radar, terrestrial laser scanning, 3D modelling, Geographyc Information Systems (GIS) are among the techniques used in the archaeological studies published in this book. The reader can learn how to use these instruments and sensors, also in combination, to investigate cultural landscapes, discover new sites, reconstruct paleo-landscapes, augment the knowledge of monuments, and assess the condition of heritage at risk. Case studies scattered across Europe, Asia and America are presented: from the World UNESCO World Heritage Site of Lines and Geoglyphs of Nasca and Palpa to heritage under threat in the Middle East and North Africa, from coastal heritage in the intertidal flats of the German North Sea to Early and Neolithic settlements in Thessaly. Beginners will learn robust research methodologies and take inspiration; mature scholars will for sure derive inputs for new research and applications

Safety and Reliability - Safe Societies in a Changing World

The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management - mathematical methods in reliability and safety - risk assessment - risk management - system reliability - uncertainty analysis - digitalization and big data - prognostics and system health management - occupational safety - accident and incident modeling - maintenance modeling and applications - simulation for safety and reliability analysis - dynamic risk and barrier management - organizational factors and safety culture - human factors and human reliability - resilience engineering - structural reliability - natural hazards - security - economic analysis in risk managemen