LOCATE-US: Indoor Positioning for Mobile Devices Using Encoded Ultrasonic Signals, Inertial Sensors and Graph- Matching

Indoor positioning remains a challenge and, despite much research and development carried out in the last decade, there is still no standard as with the Global Navigation Satellite Systems (GNSS) outdoors. This paper presents an indoor positioning system called LOCATE-US with adjustable granularity for use with commercial mobile devices, such as smartphones or tablets. LOCATE-US is privacy-oriented and allows every device to compute its own position by fusing ultrasonic, inertial sensor measurements and map information. Ultrasonic Local Positioning Systems (ULPS) based on encoded signals are placed in critical zones that require an accuracy below a few decimeters to correct the accumulated drift errors of the inertial measurements. These systems are well suited to work at room level as walls confine acoustic waves inside. To avoid audible artifacts, the U-LPS emission is set at 41.67 kHz, and an ultrasonic acquisition module with reduced dimensions is attached to the mobile device through the USB port to capture signals. Processing in the mobile device involves an improved Time Differences of Arrival (TDOA) estimation that is fused with the measurements from an external inertial sensor to obtain real-time location and trajectory display at a 10 Hz rate. Graph-matching has also been included, considering available prior knowledge about the navigation scenario. This kind of device is an adequate platform for Location-Based Services (LBS), enabling applications such as augmented reality, guiding applications, or people monitoring and assistance. The system architecture can easily incorporate new sensors in the future, such as UWB, RFiD or others.Universidad de AlcaláJunta de Comunidades de Castilla-La ManchaAgencia Estatal de Investigació

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

A Robust High-Accuracy Ultrasound Indoor Positioning System Based on a Wireless Sensor Network

This paper describes the development and implementation of a robust high-accuracy ultrasonic indoor positioning system (UIPS). The UIPS consists of several wireless ultrasonic beacons in the indoor environment. Each of them has a fixed and known position coordinate and can collect all the transmissions from the target node or emit ultrasonic signals. Every wireless sensor network (WSN) node has two communication modules: one is WiFi, that transmits the data to the server, and the other is the radio frequency (RF) module, which is only used for time synchronization between different nodes, with accuracy up to 1 μs. The distance between the beacon and the target node is calculated by measuring the time-of-flight (TOF) for the ultrasonic signal, and then the position of the target is computed by some distances and the coordinate of the beacons. TOF estimation is the most important technique in the UIPS. A new time domain method to extract the envelope of the ultrasonic signals is presented in order to estimate the TOF. This method, with the envelope detection filter, estimates the value with the sampled values on both sides based on the least squares method (LSM). The simulation results show that the method can achieve envelope detection with a good filtering effect by means of the LSM. The highest precision and variance can reach 0.61 mm and 0.23 mm, respectively, in pseudo-range measurements with UIPS. A maximum location error of 10.2 mm is achieved in the positioning experiments for a moving robot, when UIPS works on the line-of-sight (LOS) signal

A realistic evaluation of indoor positioning systems based on Wi-Fi fingerprinting: The 2015 EvAAL–ETRI competition

Pre-print versionThis paper presents results from comparing different Wi-Fi fingerprinting algorithms on the same private dataset. The algorithms where realized by independent teams in the frame of the off-site track of the EvAAL-ETRI Indoor Localization Competition which was part of the Sixth International Conference on Indoor Positioning and Indoor Navigation (IPIN 2015). Competitors designed and validated their algorithms against the publicly available UJIIndoorLoc database which contains a huge reference- and validation data set. All competing systems were evaluated using the mean error in positioning, with penalties, using a private test dataset. The authors believe that this is the first work in which Wi-Fi fingerprinting algorithm results delivered by several independent and competing teams are fairly compared under the same evaluation conditions. The analysis also comprises a combined approach: Results indicate that the competing systems where complementary, since an ensemble that combines three competing methods reported the overall best results.We would like to thank Francesco Potortì, Paolo Barsocchi, Michele Girolami and Kyle O’Keefe for their valuable help in organizing and spread the EVAALETRI competition and the off-site track. We would also like to thank the TPC members Machaj Juraj, Christos Laoudias, Antoni Pérez-Navarro and Robert Piché for their valuable comments, suggestions and reviews. Parts of this work were funded in the frame of the Spanish Ministry of Economy and Competitiveness through the “Metodologiías avanzadas para el diseño, desarrollo, evaluación e integración de algoritmos de localización en interiores” project (Proyectos I+D Excelencia, código TIN2015-70202-P) and the “Red de Posicionamiento y Navegación en Interiores” network (Redes de Excelencia, código TEC2015-71426- REDT). Parts of this work were funded in the frame of the German federal Ministry of Education and Research programme "FHprofUnt2013" under contract 03FH035PB3 (Project SPIRIT).info:eu-repo/semantics/acceptedVersio

Sensors and Systems for Indoor Positioning

This reprint is a reprint of the articles that appeared in Sensors' (MDPI) Special Issue on “Sensors and Systems for Indoor Positioning". The published original contributions focused on systems and technologies to enable indoor applications

Implementación Android de algoritmos basados en información heurística y técnicas Map Matching para la calibración de balizas US

Este Trabajo Fin de Máster desarrolla e implementa sobre una plataforma Android un algoritmo para la calibración tanto de motas ultrasónicas individuales como de balizas ultrasónicas LOCATE-US, modelo diseñado en el grupo GEINTRA y que consta de 5 transductores ultrasónicos. La herramienta permite calibrar la posición de balizas situadas tanto en el techo como en las paredes y aunque se ha desarrollado pensando en su uso con tecnología ultrasónica, puede utilizarse con otro tipo de balizas como radiofrecuencia, infrarrojos, etc. El fundamento de la calibración es la estimación de la posición de la baliza con respecto a la posición de referencia del sistema. La calibración propuesta consiste en el uso de las distancias de la baliza de estudio a las paredes cercanas medidas mediante un medidor laser. La información de dichas distancias, el mapa en formato vectorial y otros datos heurísticos (como la región de ubicación aproximada de la baliza, la orientación aproximada de las medidas y las características de las paredes de las cuales se han obtenido la distancia de la baliza a ellas) son las entradas del algoritmo propuesto que obtiene la mejor estimación de la posición de la baliza. Dado que no hay una solución cerrada al problema, se ha implementado una minimización numérica basada en el uso de algoritmos genéticos (GA) y de búsqueda armónica (HS). La propuesta se ha validado con simulaciones y experimentos reales, obteniendo correctamente la posición de las balizas incluso en entornos complejos, con paredes que presentan un cierto grado de curvatura.This study presents an algorithm developed on an Android-based platform for calibrating the position of beacons which are placed both on the ceiling and on the wall of an indoor environment. Specifically, the beacon structure to be calibrated was developed in the GEINTRA group and called LOCATE-US. It consists of five ultrasonic transducers distributed around a square structure of 70.7x70.7cm. The application also allows to calibrate individual ultrasonic spots. The notion of calibration is to estimate the position of a beacon related to a known reference system of a map. The calibration proposal consists of using several distances from the beacon to the neighbor walls measured by a laser meter. The information of these distances, the map in vector format and other heuristic data (such as the approximate localization region of the position of the beacon, the approximate orientation of the measurements and the features of the walls from which the laser meter is projected) are the inputs of the proposed algorithm that obtains the best estimation of the beacon’s position. Due to the fact that there is not an analytical solution, we have implemented a numerical minimization based on the use of a Genetic Algorithm (GA) and a Harmony Search (HS) methods. The proposal has been validated with simulations and real experiments, obtaining the position of the beacon with great accuracy.Máster Universitario en Ingeniería Industrial (M141

Sensory fusion of UBW-TOF-based location systems for mobile robotics

With the increasing need for mobile robots in industrial applications, real-time location systems, which is a crucial point in these applications, has attracted attention from many researchers around the world. Thus, robot location is the process of determining the robot position and orientation in its environment. Location systems using Ultra-WideBand (UWB) have been widely used in complex urban and indoor environments. Consequently, a moving UWB tag can be located by measuring the distances to fixed UWB anchors whose positions are known in advance. The difficulty of this approach remains in the fact that the measurements are not perfect. There will always be some noise in the measurements, and because of this, position determination could contain some errors that may result in decreased accuracy. In this work, the Pozyx performance, a low-cost Ultra-WideBand (UWB) Time-of-flight (TOF) technology solution, is studied and implemented on a mobile robot, through a beacon-based location scheme. In order to reduce the impact of measurement noise and system disturbances, the readings of odometry, Pozyx measures and the information of the lines of a known navigation path are fused to improve the estimated location of the mobile robot. Therefore, the goal of this integration is to improve the accuracy of location for indoor autonomous robots. Firstly, was studied the characterisation of the Pozyx measurement error among several test conditions. Then, an Extended Kalman Filter (EKF) algorithm is implemented using two heuristics that allow the release of the filter so that it converges to the correct robot pose after it has started to diverge. Consequently, the results obtained from the different location tests performed are presented and compared, to present the precision achieved and proving the several advantages of using heuristics. Overall, this work with Pozyx system showed that it is a proper and effective tool to improve the robot location in a challenging indoor environment given its good cost/accuracy trade-off

Smart Pipe System for a Shipyard 4.0

As a result of the progressive implantation of the Industry 4.0 paradigm, many industries are experimenting a revolution that shipyards cannot ignore. Therefore, the application of the principles of Industry 4.0 to shipyards are leading to the creation of Shipyards 4.0. Due to this, Navantia, one of the 10 largest shipbuilders in the world, is updating its whole inner workings to keep up with the near-future challenges that a Shipyard 4.0 will have to face. Such challenges can be divided into three groups: the vertical integration of production systems, the horizontal integration of a new generation of value creation networks, and the re-engineering of the entire production chain, making changes that affect the entire life cycle of each piece of a ship. Pipes, which exist in a huge number and varied typology on a ship, are one of the key pieces, and its monitoring constitutes a prospective cyber-physical system. Their improved identification, traceability, and indoor location, from production and through their life, can enhance shipyard productivity and safety. In order to perform such tasks, this article first conducts a thorough analysis of the shipyard environment. From this analysis, the essential hardware and software technical requirements are determined. Next, the concept of smart pipe is presented and defined as an object able to transmit signals periodically that allows for providing enhanced services in a shipyard. In order to build a smart pipe system, different technologies are selected and evaluated, concluding that passive and active RFID are currently the most appropriate technologies to create it. Furthermore, some promising indoor positioning results obtained in a pipe workshop are presented, showing that multi-antenna algorithms and Kalman filtering can help to stabilize Received Signal Strength (RSS) and improve the overall accuracy of the system.Comment: 43 pages, 25 figures, accepted version of Sensors journal articl

Recent Advancement in Self Emulsifing Drug Delivery System

Every day, researchers make new attempts to identify neurotherapeutics, but few of them make it to clinical trials. The main cause is their low bioavailability, which is connected to low water solubility, low permeability through biological membranes, and the hepatic first-pass metabolism. However, the most significant challenge in administering drugs to the brain is overcoming the blood-brain barrier. In order to get around it, intranasal administration has become more popular, sometimes even more so than oral administration. Because of its structure, the nasal cavity can bypass the blood-brain barrier and transport drugs to the brain directly. Nasal absorption increases the systemic bioavailability of highly processed substances because they bypass the hepatic first-pass metabolism. However, due to their unique physicochemical properties, most neurotherapeutics must be synthesized in lipidic nanosystems as self-emulsifying drug delivery systems (SEDDS). To load large quantities of lipophilic medicines into micro or nanoemulsions, these isotropic mixes of oils, surfactants, and co-surfactants are diluted in water. The goal of SEDDS is to increase the stability of labile pharmaceuticals against enzymatic activity, boost drug penetration through absorptive membranes, and reduce the likelihood of drug precipitation at absorption sites. Therefore, improved brain targeting and bioavailability of medications might be anticipated by combining the benefits of SEDDS with those of the intranasal route for brain delivery. In order to better understand the mechanisms involved in the intranasal administration of pharmaceuticals loaded in SEDDS, this paper provides a comprehensive characterization of SEDDS as a lipidic nanosystem. Finally, the in vivo effects of intranasal or oral delivery of SEDDS, showing their superiority over standard solutions or suspensions, are described