Design, Calibration, and Evaluation of a Long-Range 3-D Infrared Positioning System Based on Encoding Techniques

Optical indoor positioning systems have experienced an increasing research interest during last years as they can provide 3D centimeter accuracy using LED lighting. In the case of having several LEDs emitting simultaneously and a receiver (e.g. the tag to be localized), these systems face important challenges, such as very high dynamic ranges with low Signal-to-Noise Ratios when the coverage area is increased, Multiple Access Interference (MAI), multipath and near-far effects, calibration issues (misalignments in the receiver and other intrinsic parameters), and so on. Previous work have already shown the feasibility of using LED emitters in combination with Quadrature Angular Diversity Aperture (QADA) receivers to implement positioning systems. This work further introduces new design considerations, tested on an experimental setup, to enlarge the emitter-receiver range, thus increasing the total coverage, while dealing with the aforementioned challenges. The system applies encoding techniques to each transmitter to solve the multiple access problem. The performance of two different types of codes has been compared, as well as their influence on the final estimation of the receiver?s position: one based on Kasami sequences and another based on Loosely Synchronous (LS) codes, derived from Complementary Sets of Sequences. At the receiver, the estimation of the incident point is constrained to angles at which the system can be linearized, and a specific calibration process for this type of sensor has also been defined and applied. The proposal has been finally validated with both, simulated and experimental results, in a large space of 2 2m2 (base), with a distance from transmitters to receiver of 3:4m (height). The experimental tests at distances up to 4 m, carried out after the calibration process, achieve average absolute errors bellow 10 cm for X and Y axis and around 20 cm for Z, and standard deviations below 4 cm for X and Y , and around 30 cm for Z.Agencia Estatal de InvestigaciónUniversidad de Alcal

A survey on acoustic positioning systems for location-based services

Positioning systems have become increasingly popular in the last decade for location-based services, such as navigation, and asset tracking and management. As opposed to outdoor positioning, where the global navigation satellite system became the standard technology, there is no consensus yet for indoor environments despite the availability of different technologies, such as radio frequency, magnetic field, visual light communications, or acoustics. Within these options, acoustics emerged as a promising alternative to obtain high-accuracy low-cost systems. Nevertheless, acoustic signals have to face very demanding propagation conditions, particularly in terms of multipath and Doppler effect. Therefore, even if many acoustic positioning systems have been proposed in the last decades, it remains an active and challenging topic. This article surveys the developed prototypes and commercial systems that have been presented since they first appeared around the 1980s to 2022. We classify these systems into different groups depending on the observable that they use to calculate the user position, such as the time-of-flight, the received signal strength, or the acoustic spectrum. Furthermore, we summarize the main properties of these systems in terms of accuracy, coverage area, and update rate, among others. Finally, we evaluate the limitations of these groups based on the link budget approach, which gives an overview of the system's coverage from parameters such as source and noise level, detection threshold, attenuation, and processing gain.Agencia Estatal de InvestigaciónResearch Council of Norwa

Implantación de la normativa IMO2020 y su consecuencia en los buques mercantes

Grado En Náutica Y Transporte MarítimoEn este trabajo se analiza la nueva normativa sobre las emisiones de Óxidos de Azufre (SOx) establecida por la Organización Marítima Internacional (OMI) que establece nuevas restricciones para conservar el medioambiente reduciendo las emisiones que emanan de los buques mercantes. Dicha normativa, llevará a tener un planeta mucho más sostenible y con menos emisiones contaminantes. Se llevarán a cabo controles exhaustivos para el cumplimiento de dicha norma por parte de todos los buques mercantes, además de, sancionar toda aquella situación que no se ajuste a la nueva norma. Todo esto, ha llevado a la aparición de nuevos combustibles con bajas cantidades de azufre que cumplan con la normativa, o la aparición de nuevos combustibles más eficientes como ha sido el GNL, un combustible más limpio y con gran proyección. Esta nueva situación obliga a las navieras a tener que optar un cambio de combustibles o a realizar una inversión en nuevas instalaciones, como sería el caso de las torres de lavado (scrubbers), una manera de limpiar los gases con el fin de adaptarse a la normativa. Se observa un análisis de la evolución de los combustibles convencionales donde se aprecia el efecto que ha tenido la nueva normativa en los precios. Además, por su parte la OMI pone a disposición un plan de implantación uniforme para el límite de azufre en virtud del anexo VI del MARPOL para todos los buques y así ayudar a que el cambio sea mucho más fácil. De cara al futuro, se están llevando a cabo proyectos de investigación con nuevos combustibles con el fin de encontrar combustibles más eficientes y que no afecten al medioambiente.The new regulations about emissions of Sulfur Oxides (SOx) established by the International Maritime Organization (IMO) is analyzed. It establishes new restrictions to conserve the environment by reducing the emissions that emanate from merchant ships. These regulations will lead to a much more sustainable planet with less polluting emissions. Exhaustive controls will be carried out for compliance with this rule by all merchant ships, in addition to sanctioning any situation that does not comply with the new rule. All this has led to the appearance of new fuels with low amounts of sulfur that comply with regulations, or the appearance of new, more efficient fuels such as LNG, a cleaner fuel with great projection. This new situation forces shipping companies to have to choose a fuel change or to make an investment in new facilities, such as scrubbers, a way to clean gases in order to adapt to regulations. An analysis of the evolution of conventional fuels is observed, showing the effect that the new regulations have had on prices. Furthermore, the IMO makes available an uniform implementation plan for the sulfur limit under Annex VI of MARPOL for all ships, thus helping to make the change much easier. Looking ahead, research projects with new fuels are being carried out in order to find more efficient fuels that do not affect the environment

Combined infrared-ultrasonic positioning system to improve the data availability

Many indoor positioning applications related to accurate monitoring and tracking targets require centimeter precision. Infrared (IR)- and ultrasound (US)-based systems represent a feasible approach providing high robustness against interference. Furthermore, their combination may achieve better performance by mitigating their complementary drawbacks, covering larger areas, and improving the availability of positioning measurements. In this context, this work presents the proposal and experimental evaluation of a tightly coupled fusion method that uses an extended Kalman filter (EKF) to merge an IR- and a US-based positioning system. An outlier detection method is considered to select measurements with an adequate performance. Experimental results reveal that the IR and US systems are unable to position in 4.08% and 26.06% of locations, whereas the combined IR -US system has 100% of availability. In addition, the merged solution achieves less than 4 cm of positioning error in 90% of cases, outperforming the IR and US systems when they work independently

Appliance Identification in NILM Applications by means of a Convolutional Auto-Encoder

n energy efficiency applications, Non-Intrusive Load Monitoring techniques (NILM) are typically used to deduce which electrical loads are being used in a building at a given time. The identification of household appliances, in particular manually operated ones, is relevant information that can also be applied to infer the routines of tenants in Active and Assisted Living environments (AAL). These tools and applications are becoming increasingly interesting, especially in Western countries, where the ageing population is putting a strain on public social and health services. In this context, this work aims to classify the on/off events of the devices considered in the BLUED database. For this purpose, an architecture is presented, consisting of a Convolutional Auto-Encoder (CAE) followed by a classifier neural network. The CAE is used to implement a dimensionality reduction process after the encoder. Input data are formatted as images, created with extracted sections of the high-frequency electric current signal captured around the switching events. It is noteworthy that this dimensionality reduction also allows a decrease in the computational load of the classifier. Regarding the CAE functionality, the reconstruction error reaches a value of 1.579 · 10−3, whereas in the validation stage a weighted average classification F1-score of 87 % is obtained for the whole architecture

Experimental Evaluation of a Machine Learning-Based RSS Localization Method Using Gaussian Processes and a Quadrant Photodiode

The research interest on indoor Location-Based Services (LBS) has increased during the last years, especially using LED lighting, since they can deal with the dual functionality of lighting and localization with centimetric accuracy. There are several positioning approaches using lateration and angular methods. These methods typically rely on the physical model to deal with the multipath effect, environmental fluctuations, calibration of the optical setup, etc. A recent approach is the use of Machine Learning (ML) techniques. ML techniques provide accurate location estimates based on observed data without requiring the underlying physical model to be described. This work proposes an optical indoor local positioning system based on multiple LEDs and a quadrant photodiode plus an aperture. Different frequencies are used to allow the simultaneous emission of all transmitted signals and their processing at the receiver. For that purpose, two algorithms are developed. First, a triangulation algorithm based on Angle of Arrival (AoA) measurements, which uses the Received Signal Strength (RSS) values from every LED on each quadrant to determine the image points projected from each emitter on the receiver and, then, implements a Least Squares Estimator (LSE) and trigonometric considerations to estimate the receiver?s position. Secondly, the performance of a data-driven approach using Gaussian Processes is evaluated. The proposals have been experimentally validated in an area of 3 × 3m2 and a height of 1.3m (distance from transmitters to receiver). The experimental tests achieve p50 and p95 2D absolute errors below 9.38 cm and 21.94 cm for the AoA-based triangulation algorithm, and 3.62 cm and 16.65 cm for the Gaussian Processes.Agencia Estatal de Investigació

Visible light positioning system based on a quadrant photodiode and encoding techniques

Visible light positioning systems (VLPSs) are a feasible alternative to local positioning systems due to the technology improvement and massive use of light-emitting diodes (LEDs). Compared to other technologies, VLPSs can provide significant advantages, such as the achieved accuracy, although they still present some issues, mainly related to the reduced coverage area or the high computational load. This article proposes the design of a VLPS based on four LED lamps as transmitters and a quadrant photodiode angular diversity aperture (QADA) as a receiver. As the shape of the QADA is circular and the aperture to be installed over it is square, we derive the corresponding general equations to obtain the currents through the different pads of the QADA, regarding the angle of incidence of the light (and, inversely, how to estimate the angle of incidence from the measured currents). An encoding scheme based on 1023-bit Kasami sequences is proposed for every transmission from the LED lamps, thus providing multiple access capability and robustness against low signal-to-noise ratios and harsh conditions, such as multipath and near-far effect. A triangulation technique has been applied to estimate the receiver's position, by means of the least-squares estimator (LSE), together with some geometrical considerations. The proposal has been validated by simulation and by experimental tests, obtaining 3-D positioning average errors below 13 and 5.5 cm for separations between the transmitters' plane and the receiver of 2 and 1 m, respectively

Propuestas para mejorar la calidad de vida en las ciudades

En general, con algunas excepciones en ciudades medias e intermedias y algunos casos singulares, las ciudades españolas están empezando a pagar graves facturas sociales y ambientales derivadas del modelo urbano mantenido en las últimas décadas y que, finalmente, se traduce en términos de empeoramiento de la calidad de vida individual y comunitaria. La calidad de vida es un concepto complejo y transversal, que abarca dimensiones económicas, sociales, ambientales y físico-espaciales, tanto a nivel individual como colectivo. Los modelos y las políticas urbanas contribuyen a mejorar o empeorar la calidad de vida de sus ciudadanos y, por eso, hay que prestar mucha atención a la definición de objetivos a medio y largo plazo. La calidad de vida de los ciudadanos depende de factores sociales y económicos, y también de las condiciones ambientales y físico-espaciales, y la forma urbana condiciona, asimismo, cada uno de estos factores. Sabiendo la complejidad del tema, el informe propone actuaciones sectoriales que, en su conjunto, pueden abarcar muchos de los aspectos que afectan a la vida cotidiana de los ciudadanos. Estas actuaciones tienen que ver con los siguientes aspectos: a) Un urbanismo para los ciudadanos, que permita ejercer la libertad individual desde la responsabilidad social. b) Una movilidad racional que optimice el tiempo. c) El respeto por el medio ambiente y el cumplimiento de los compromisos para evitar el calentamiento del planeta. d) El acceso a la vivienda, a los equipamientos y a las dotaciones. e) La mejora de la habitabilidad y de la recuperación del patrimonio construido. f) La participación de los ciudadanos en la toma de decisiones de los procesos que les afectan. Entendemos que los gobiernos locales son los organismos adecuados para llevar a cabo muchas de las propuestas que se recogen en este documento. Para ello, además de su voluntad política y su compromiso con la ciudadanía, es necesario dotarles de las herramientas e instrumentos necesarios para abordar programas integrales destinados, en último término, a mejorar la calidad de vida de los ciudadanos. En el contexto actual, consideramos que estos dos conceptos (calidad de vida y sostenibilidad) son indisolubles, en cuanto que ambos se apoyan en los mismos principios sociales, ambientales y económicos. Desde ese marco, que es el que va a configurar el modelo de ciudad propuesto, se detecta la primera de las carencias en la gestión urbana: la falta de visión a largo plazo y de coordinación de las políticas sectoriales. Por lo tanto, la primera reivindicación de carácter genérica para mejorar la calidad de vida en las ciudades es potenciar instrumentos que permitan la coordinación transversal de las actuaciones. Partiendo de este marco general, en este estudio se proponen cuatro ámbitos sectoriales en los que actuar: movilidad, lucha contra el cambio climático, acceso a la vivienda y rehabilitación de la ciudad construida. De forma sintética, las propuestas que se plantean se pueden resumir en: - Mantener un enfoque integrador, huyendo de políticas urbanas sectoriales y desarticuladas. - Las ciudades deben estar comprometidas con la lucha contra el cambio climático; las políticas de ámbito local de reducción de emisiones en el transporte y la edificación son fundamentales para mejorar la calidad de vida, tanto en el entorno próximo como en el conjunto del planeta. - Siendo el tema del transporte una de las principales cuestiones que inciden en la calidad de vida de los ciudadanos, las propuestas deben basarse en la elaboración de estrategias globales (municipales, autonómicas o estatales) sobre movilidad sostenible. - La vivienda debe tratarse como un tema transversal, vinculándolo a otros aspectos sin los cuales no tiene sentido: necesidades sociales de la población y procesos de construcción de la ciudad. - La recuperación de las edificaciones existentes y la reducción de sus impactos ambientales son temas trascendentales para la mejora de la calidad de vida en las ciudades. .............. Maintain an inclusive approach, avoiding urban policies and sectors dismantled. Cities must be committed to the fight against climate change, the local policies to reduce emissions in the transport and building are essential for improving the quality of life, both in the immediate environment as throughout the world. Being the subject of a major transport issues affecting the quality of life of citizens, the proposals should be based on strategies aggregate (municipal, regional or state) on sustainable mobility. The home should be treated as a crosscutting theme, linking it to other aspects without which makes no sense: social needs of the population and construction processes of the city. The recovery of existing buildings and reducing their impact. Environmental issues are important for improving the quality of life in cities

Comparison of Neural Networks for High-Sampling Rate NILM Scenario

2022 IEEE International Symposium on Medical Measurements and Applications (MeMeA), 22-24 June 2022, Messina, Italy.The common objective of techniques employed to identify the use of household appliances is related to energy efficiency and the reduction of energy consumption. In addition, through load monitoring it is possible to assess the degree of independence of tenants with minimal invasion of privacy and thus develop sustainable health systems capable of providing the required services remotely. Both approaches should initially deal with the load identification stage. For that purpose, this work presents three different solutions that take the events of the electrical current signal acquired at high frequency and process them for classification by using two different topologies of Artificial Neural Networks (ANN). The data of interest used as input for the ANN in the proposals are the normalized signal captured around the events, the images created by dividing that signal into sections and organizing them in a matrix, and the images coming from the Short Time Fourier Transform (STFT) of the signal around the event. The dataset BLUED is used to carry out the validation of the proposal, where some of the proposed architectures obtain an F1 score above 90% for more than fifteen devices under classification.Universidad de AlcaláAgencia Estatal de Investigació

Dynamic Adjustment of Measurement Noise Covariance Matrix in an Infrared-based Positioning and Tracking System

2022 IEEE 12th International Conference on Indoor Positioning and Indoor Navigation (IPIN), 5-8 September, 2022, Beijing, China.The accuracy of optical positioning systems can be compromised by multiple factors (reflections, calibration, etc.). As an alternative to the triangulation, multilateration, or fingerprinting techniques typically used in these systems, stochastic estimation techniques can be used, such as Kalman Filters (KF) in its different variants. They estimate the receiver position based on the acquired measurements and the estimated positions in previous iterations. This work presents the evaluation of a 3D optical positioning system, based on four LED beacons and a quadrant receiver, using an Extended Kalman Filter (EKF). The implementation of a measurement noise covariance matrix that is adjusted depending on the angle and distance between transmitters and receiver, obtained in the previous iteration, is analysed. The receiver position estimation using both a dynamic and a static measurement noise covariance matrix is evaluated and compared with simulations and experimental tests. In simulations, the achieved errors are below 6 cm and 12 cm in 75% of the cases when using a dynamic and a static noise matrix, respectively. In the experimental tests, the obtained errors in 75% of the cases for the position in plane XY and the rotation angle ? are smaller than 7.44 cm and 1.06 ? with a dynamic noise matrix; and below 7.59 cm and 1.62 ? for a static one.Agencia Estatal de InvestigaciónUniversidad de Alcal