Mobile Indoor Augmented Reality. Exploring applications in hospitality environments.

Augmented reality (AR) is been increasingly used in mobile devices. Most of the available applications are set to work outdoors, mainly due to the availability of a reliable positioning system. Nevertheless, indoor (smart) spaces offer a lot of opportunities of creating new service concepts. In particular, in this paper we explore the applicability of mobile AR to hospitality environments (hotels and similar establishments). From the state-of-the-art of technologies and applications, a portfolio of services has been identified and a prototype using off-the-shelf technologies has been designed. Our objective is to identify the next technological challenges to overcome in order to have suitable underlying infrastructures and innovative services which enhance the traveller?s experience.

An energy-efficient strategy for combined RSS-PDR indoor localization

We propose an optimization-based framework to minimize the energy consumption in a sensor network when using an indoor localization system based on the combination of received signal strength (RSS) and pedestrian dead reckoning (PDR). The objective is to find the RSS localization frequency and the number of RSS measurements used at each localization round that jointly minimize the total consumed energy, while ensuring at the same time a desired accuracy in the localization result. The optimization approach leverages practical models to predict the localization error and the overall energy consumption for combined RSS-PDR localization systems. The performance of the proposed strategy is assessed through simulation, showing energy savings with respect to other approaches while guaranteeing a target accuracy.

A Bayesian strategy to enhance the performance of indoor localization systems

This work describes the probabilistic modelling af a Bayesian-based mechanism to improve location estimates of an already deployed location system by fusing its outputs with low-cost binary sensors. This mechanism takes advantege of the localization captabilities of different technologies usually present in smart environments deployments. The performance of the proposed algorithm over a real sensor deployment is evaluated using simulated and real experimental data.

Particle filtering for indoor RFID tag tracking

In this paper, we propose a particle filtering (PF) method for indoor tracking using radio frequency identification (RFID) based on aggregated binary measurements. We use an Ultra High Frequency (UHF) RFID system that is composed of a standard RFID reader, a large set of standard passive tags whose locations are known, and a newly designed, special semi-passive tag attached to an object that is tracked. This semi-passive tag has the dual ability to sense the backscatter communication between the reader and other passive tags which are in its proximity and to communicate this sensed information to the reader using backscatter modulation. We refer to this tag as a sense-a-tag (ST). Thus, the ST can provide the reader with information that can be used to determine the kinematic parameters of the object on which the ST is attached. We demonstrate the performance of the method with data obtained in a laboratory environment.

A Radio Frequency Identification System for accurate indoor localization

In this paper we present a novel Radio Frequency Identification (RFID) system for accurate indoor localization. The system is composed of a standard Ultra High Frequency (UHF), ISO-18006C compliant RFID reader, a large set of standard passive RFID tags whose locations are known, and a newly developed tag-like RFID component that is attached to the items that need to be localized. The new semi-passive component, referred to as sensatag (sense-a-tag), has a dual functionality wherein it can sense the communication between the reader and standard tags which are in its proximity, and also communicate with the reader like standard tags using backscatter modulation. Based on the information conveyed by the sensatags to the reader, localization algorithms based on binary sensor principles can be developed. We present results from real measurements that show the accuracy of the proposed system.

Characterization of thin film PV modules under standard test conditions: Results of indoor and outdoor measurements and the effects of sunlight exposure

Photovoltaic modules based on thin film technology are gaining importance in the photovoltaic market, and module installers and plant owners have increasingly begun to request methods of performing module quality control. These modules pose additional problems for measuring power under standard test conditions (STC), beyond problems caused by the temperature of the module and the ambient variables. The main difficulty is that the modules’ power rates may vary depending both on the amount of time they have been exposed to the sun during recent hours and on their history of sunlight exposure. In order to assess the current state of the module, it is necessary to know its sunlight exposure history. Thus, an easily accomplishable testing method that ensures the repeatability of the measurements of the power generated is needed. This paper examines different tests performed on commercial thin film PV modules of CIS, a-Si and CdTe technologies in order to find the best way to obtain measurements. A method for obtaining indoor measurements of these technologies that takes into account periods of sunlight exposure is proposed. Special attention is paid to CdTe as a fast growing technology in the market.

Indoor characterization at production sccale: 200 kWp of CPV solar simulator measurements

In order to complement ISFOC’s characterization capabilities, a Helios 3198 CPV Solar Simulator was installed in summer 2010. This Solar Simulator, based on a parabolic mirror and a high-intensity, small area Xenon flash lamp was developed by the Instituto de Energía Solar in Madrid [1] and is manufactured and distributed by Soldaduras Avanzadas [2]. This simulator is used not only for R&D purposes, but as a quality control tool for incoming modules that are to be installed in ISFOC’s CPV plants. In this paper we will discuss the results of recent measurements of close to 5000 modules, the entire production of modules corresponding to a small CPV power plant (200 kWp). We scrutinize the resultant data for signs of drift in the measurements, and analyze the light quality before and after, to check for changes in spectrum or spatial uniformity.)

Accurate pedestrian indoor navigation by tightly coupling foot-mounted IMU and RFID measurements

We present a new method to accurately locate persons indoors by fusing inertial navigation system (INS) techniques with active RFID technology. A foot-mounted inertial measuring units (IMUs)-based position estimation method, is aided by the received signal strengths (RSSs) obtained from several active RFID tags placed at known locations in a building. In contrast to other authors that integrate IMUs and RSS with a loose Kalman filter (KF)-based coupling (by using the residuals of inertial- and RSS-calculated positions), we present a tight KF-based INS/RFID integration, using the residuals between the INS-predicted reader-to-tag ranges and the ranges derived from a generic RSS path-loss model. Our approach also includes other drift reduction methods such as zero velocity updates (ZUPTs) at foot stance detections, zero angular-rate updates (ZARUs) when the user is motionless, and heading corrections using magnetometers. A complementary extended Kalman filter (EKF), throughout its 15-element error state vector, compensates the position, velocity and attitude errors of the INS solution, as well as IMU biases. This methodology is valid for any kind of motion (forward, lateral or backward walk, at different speeds), and does not require an offline calibration for the user gait. The integrated INS+RFID methodology eliminates the typical drift of IMU-alone solutions (approximately 1% of the total traveled distance), resulting in typical positioning errors along the walking path (no matter its length) of approximately 1.5 m.

Radio propagation modeling and measurements for ZigBee based indoor wireless sensor networks

The deployment of nodes in Wireless Sensor Networks (WSNs) arises as one of the biggest challenges of this field, which involves in distributing a large number of embedded systems to fulfill a specific application. The connectivity of WSNs is difficult to estimate due to the irregularity of the physical environment and affects the WSN designers? decision on deploying sensor nodes. Therefore, in this paper, a new method is proposed to enhance the efficiency and accuracy on ZigBee propagation simulation in indoor environments. The method consists of two steps: automatic 3D indoor reconstruction and 3D ray-tracing based radio simulation. The automatic 3D indoor reconstruction employs unattended image classification algorithm and image vectorization algorithm to build the environment database accurately, which also significantly reduces time and efforts spent on non-radio propagation issue. The 3D ray tracing is developed by using kd-tree space division algorithm and a modified polar sweep algorithm, which accelerates the searching of rays over the entire space. Signal propagation model is proposed for the ray tracing engine by considering both the materials of obstacles and the impact of positions along the ray path of radio. Three different WSN deployments are realized in the indoor environment of an office and the results are verified to be accurate. Experimental results also indicate that the proposed method is efficient in pre-simulation strategy and 3D ray searching scheme and is suitable for different indoor environments.

Effectiveness of improved cookstoves to reduce indoor air pollution in developing countries. The case of the cassamance natural subregion, Western Africa

The Spanish NGO "Alianza por la Solidaridad" has installed improved cookstoves in 3000 households during 2012 and 2013 to improve energy efficiency reducing fuelwood consumption and to improve in-door air quality. The type of cookstoves were Noflaye Jeeg and Noflaye Jaboot and were installed in the Cassamance Natural Subregion covering part of Senegal, The Gambia and Guinea-Bissau. The Technical University of Madrid (UPM) has conducted a field study on a sample of these households to assess the effect of improved cookstoves on kitchen air quality. Measurements of carbon monoxide (CO) and fine particle matter (PM2.5) were taken for 24-hr period before and after the installation of improved cook-stoves. The 24-hr mean CO concentrations were lower than the World Health Organization (WHO) guidelines for Guinea-Bissau but higher for Senegal and Gambia, even after the installation of improved cookstoves. As for PM2.5 concentrations, 24-hr mean were always higher than these guidelines. However, improved cookstoves produced significant reductions on 24-hr mean CO and PM2.5 concentrations in Senegal and for mean and maximum PM2.5 concentration on Gambia. Although this variability needs to be explained by further research to determine which other factors could affect indoor air pollution, the study provided a better understanding of the problem and envisaged alternatives to be implemented in fu-ture phases of the NGO project.

Simulation of impulse response for indoor visible light communications using 3D CAD models

n this article, a tool for simulating the channel impulse response for indoor visible light communications using 3D computer-aided design (CAD) models is presented. The simulation tool is based on a previous Monte Carlo ray-tracing algorithm for indoor infrared channel estimation, but including wavelength response evaluation. The 3D scene, or the simulation environment, can be defined using any CAD software in which the user specifies, in addition to the setting geometry, the reflection characteristics of the surface materials as well as the structures of the emitters and receivers involved in the simulation. Also, in an effort to improve the computational efficiency, two optimizations are proposed. The first one consists of dividing the setting into cubic regions of equal size, which offers a calculation improvement of approximately 50% compared to not dividing the 3D scene into sub-regions. The second one involves the parallelization of the simulation algorithm, which provides a computational speed-up proportional to the number of processors used.

Effectiveness of improved cookstoves to reduce indoor air pollution in developing countries. The case of the Cassamance Natural Subregion, Western Africa

The Spanish NGO "Alianza por la Solidaridad" has installed improved cookstoves in 3000 households during 2012 and 2013 to improve energy efficiency reducing fuelwood consumption and to improve indoor air quality. The type of cookstoves were Noflaye Jeeg and Noflaye Jaboot and were installed in the Cassamance Natural Subregion covering part of Senegal, The Gambia and Guinea-Bissau. The Technical University of Madrid (UPM) has conducted a field study on a sample of these households to assess the effect of improved cookstoves on kitchen air quality. Measurements of carbon monoxide (CO) and fine particle matter (PM2.5) were taken for 24-hr period before and after the installation of improved cookstoves. The 24-hr mean CO concentrations were lower than the World Health Organization (WHO) guidelines for Guinea-Bissau but higher for Senegal and Gambia, even after the installation of improved cookstoves. As for PM2.5 concentrations, 24-hr mean were always higher than these guidelines. However, improved cookstoves produced significant reductions on 24-hr mean CO and PM2.5 concentrations in Senegal and for mean and maximum PM2.5 concentration on Gambia. Although this variability needs to be explained by further research to determine which other factors could affect indoor air pollution, the study provided a better understanding of the problem and envisaged alternatives to be implemented in future phases of the NGO project.

Indoor positioning using Android Platform

In recent years, there has been a great increase in the development of wireless technologies and location services. For this reason, numerous projects in the location field, have arisen. In addition, with the appearance of the open Android operating system, wireless technologies are being developed faster than ever. This Project approaches the design and development of a system that combines the technologies of wireless, location and Android with the implementation of an indoor positioning system. As a result, an Android application has been obtained, which detects the position of a phone in a simple and useful way. The application is based on the WIFI manager API of Android. It combines the data stored in a SQL database with the wifi data received at any given time. Afterwards the position of the user is determined with the algorithm that has been implemented. This application is able to obtain the position of any person who is inside a building with Wi-Fi coverage, and display it on the screen of any device with the Android operating system. Besides the estimation of the position, this system displays a map that helps you see in which quadrant of the room are positioned in real time. This system has been designed with a simple interface to allow people without technology knowledge. Finally, several tests and simulations of the system have been carried out to see its operation and accuracy. The performance of the system has been verified in two different places and changes have been made in the Java code to improve its precision and effectiveness. As a result of the several tests, it has been noticed that the placement of the access point (AP) and the configuration of the Wireless network is an important point that should be taken into account to avoid interferences and errors as much as possible, in the estimation of the position. RESUMEN. En los últimos años, se ha producido un incremento en el desarrollo de tecnologías inalámbricas y en servicios de localización y posicionamiento. Por esta razón, han surgido numerosos proyectos relacionados con estas tecnologías. Por otra parte, un punto importante en el desarrollo de estas tecnologías ha sido la aparición del lenguaje Android que ha hecho que estas nuevas tecnologías se implementaran con una mayor rapidez. Este proyecto, se acerca al diseño y desarrollo de un sistema que combina tecnologías inalámbricas, de ubicación y uso de lenguaje Android para el desarrollo de una aplicación de un sistema de posicionamiento en interiores. Como consecuencia de esto se ha obtenido una aplicación Android que detecta la posición de un dispositivo móvil de una manera sencilla e intuititva. La aplicación se basa en la API WIFI de Android, que combina los datos almacenados en una base de datos SQL con los datos recibidos vía Wi-Fi en cualquier momento. A continuación, la posición del usuario se determina con el algoritmo que se ha implementado a lo largo de todo el proyecto utilizando código Android. Esta aplicación es capaz de obtener la posición de cualquier persona que se encuentra dentro de un edificio con cobertura Wi-Fi, mostrando por pantalla la ubicación del usuario en cualquier dispositivo que disponga de sistema operativo Android. Además de la estimación de la posición, este sistema muestra un mapa que le ayuda a ver en qué cuadrante de la sala está situado el usuario. Este sistema ha sido diseñado con una interfaz sencilla para permitir que usuarios sin conocimiento tecnológico o no acostumbrados al uso de los nuevos dispositivos de hoy en día puedan usarlo de una manera sencilla y de forma intuitiva. Por último, se han llevado a cabo varias pruebas y simulaciones del sistema para verificar su funcionamiento y precisión. El rendimiento del sistema se ha comprobado en dos puntos diferentes de la sala (lugar donde se han hecho todas las pruebas y desarrollado la aplicación) realizando cambios en el código Java para mejorar aún más la precisión y eficacia del posicionamiento. Como resultado de todo esto, se ha comprobado que la ubicación del punto de acceso (AP) y la configuración de la red inalámbrica es importante, y por ello se debe de tener en cuenta para evitar interferencias y tantos errores como sea posible en la estimación de la posición.

Optimization of multijunction solar cells through indoor energy yield measurements

The variability of the solar spectra in the field may reduce the annual energy yield of multijunction solar cells. It would, therefore, be desirable to implement a cell design procedure based on the maximization of the annual energy yield. In this study, we present a measurement technique to generate maps of the real performance of the solar cell for a range of light spectrum contents using a solar simulator with a computer-controllable spectral content. These performance maps are demonstrated to be a powerful tool for analyzing the characteristics of any given set of annual spectra representative of a site and their influence on the energy yield of any solar cell. The effect of luminescence coupling on buffering against variations of the spectrum and improving the annual energy yield is demonstrated using this method.

A Vision-based Quadrotor Multi-robot Solution for the Indoor Autonomy Challenge of the 2013 International Micro Air Vehicle Competition

This paper presents a completely autonomous solution to participate in the Indoor Challenge of the 2013 International Micro Air Vehicle Competition (IMAV 2013). Our proposal is a multi-robot system with no centralized coordination whose robotic agents share their position estimates. The capability of each agent to navigate avoiding collisions is a consequence of the resulting emergent behavior. Each agent consists of a ground station running an instance of the proposed architecture that communicates over WiFi with an AR Drone 2.0 quadrotor. Visual markers are employed to sense and map obstacles and to improve the pose estimation based on Inertial Measurement Unit (IMU) and ground optical flow data. Based on our architecture, each robotic agent can navigate avoiding obstacles and other members of the multi-robot system. The solution is demonstrated and the achieved navigation performance is evaluated by means of experimental flights. This work also analyzes the capabilities of the presented solution in simulated flights of the IMAV 2013 Indoor Challenge. The performance of the CVG UPM team was awarded with the First Prize in the Indoor Autonomy Challenge of the IMAV 2013 competition.