1,721,039 research outputs found
Study and development of harmonic detection flexible sensors for sensitive functionalisation of surfaces
No full textL’avènement des interfaces tactiles ouvre des perspectives d’enrichissement de l’interaction entre l’homme et la machine. Nous proposons un nouveau concept de surfaces tactiles souples dont l’objectif est d’étudier l’interaction entre le signal électrique et l’environnement résistif et diélectrique du support, afin de réaliser le système d’acquisition fournissant une information exploitable par la machine.La base technologique est un guide d’ondes sur substrat souple sur lequel le toucher crée une réflexion au port d’entrée. Nous avons développé une méthode de localisation alternative à la réflectométrie temporelle, nommée Harmonic Detection and Location (HDL), permettant l’utilisation d’une électronique d’acquisition de faible complexité, en bande étroite, autour de 100 MHz. Le concept a été validé à partir de mesures sur des dalles tactiles souples et rigides connectées à un analyseur de réseau, utilisé comme référence. Un système d’acquisition compact basé sur un pont de Wheatstone associé à un détecteur de phase a été développé. Pour ce faire, un travail de caractérisation et d’identification des sources d’erreurs a été mené sur les interactions électromagnétiques entre le doigt et le guide d’onde, les imperfections du guide d’onde et la nature du substrat ainsi que l’impact des erreurs induites par l’électronique d’acquisition.Cette connaissance a permis de co-développer la partie matérielle et l’algorithme de détection pour démontrer une précision de localisation de 2cm. Les fondamentaux posés dans ce travail ouvrent la possibilité de réalisation d’interfaces de grande surface, avec une connectique simple, conformables sur des objets sensitifs en trois dimensionsThe advent of sensitive interfaces is promising prospects to the human-machine interaction. We propose a new concept of sensitive flexible surface. Its aim is to study the interaction between electrical signal and resistive and dielectric environment of the support in order to realize an acquisition system providing machine readable information.The technological base is a waveguide on flexible substrate on which the touch creates a reflection at the input port. We have developed a location method as an alternative to the time domain reflectometry (TDR). It is named Harmonic Detection and Location (HDL) and it allows using a narrow band, around 100 MHz, low complexity acquisition system. The concept has been approved using measures on flexible and rigid sensitive surfaces connected to a vector network analyzer (VNA) used as reference. A compact acquisition system based on a Wheatstone bridge associated to a phase detector has been developed. For this purpose, errors characterization and identification work has been done. Electromagnetic interactions between the finger and the waveguide, waveguide imperfections, substrate nature and acquisition system errors’ impact have been studied. This knowledge has provided the possibility to co-develop the hardware and the detection algorithm to demonstrate a location accuracy of 2cm. Fundamental principles of this work provide the possibility of realizing large surface interfaces, with simple connection and conformable, for 3D sensitive objects
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Using a simple geolocation symbolic system in the framework of E-health
No full textInternational audienceWe describe our symbolic positioning approaches by showing on implementations in hospitals and medical facilities how it is possible to use a very reliable but not always accurate geolocation. The measurements made, the associated treatments (with a critical view) as well as the achievable performances (and limitations) are exposed.The technical approaches, both in the estimation and calculation of positions, as well as the hardware and network aspects, necessary for a meaningful implementation, are thoroughly discussed.Such systems are also possible in much more classical cases of "navigation" of people, but this is not the objective of this presentation, which is more based on the advanced uses of geolocalized data. Offering more freedom in medical facilities while ensuring the safety of residents, ensuring the optimization and planning of emergency services or improving the management of ambulatory activities in hospitals are quantified with the help of experimental results in real conditions carried out in the services. It is shown, for example, that planning the movement of a stretcher is feasible with a reasonable deployment of means and greatly relieves the burden of logistics management.A last part is based on the case of the individual's home. Here again, we show that a kind of monitoring of a person's daily activity can be achieved with simple geolocation technical means. The aim is not to have a precise record of the movements, but to highlight an "anomaly" of behavior without being too intrusive. This allows a gradual approach to E-HealthCare
Symbolic 3D WiFi indoor positioning system : a deployment and performance evaluation tool
No full textInternational audienceIn many location based applications there is no real need for accuracy, but rather for reliability. For example, the fact to know someone is in a specific room, corridor or office is often sufficient. This is the basis of the symbolic approach that gives a positioning in terms of rooms (or group of rooms). Developed algorithms have then a clear target: to provide high reliability in a typical 3D environment, together with real time indicators of both accuracy and reliability. The WLAN symbolic system has also been designed in order to provide a positioning without any calibration phase and that still works even in "real telecommunication environments", i.e. with a reduced set of Access Points (it still works with only one Access Point, although the accuracy of the positioning is then really poor). In addition, the symbolic approach is scalable and easy to adapt to particular needs such as an increased accuracy in specific areas or positioning in a complex 3D building. We developed a tool that allows a user to evaluate the positioning performance of its WiFi network, using the symbolic method. Default values of the various parameters allow a straight forward approach, although a reduced set of initial measurements (a "not more than five minutes" calibration) is bound to provide a better positioning estimation. This tool is also useful in improving the WLAN network deployment for positioning purposes in helping to find the best locations of the Access Points. In addition, it helps in defining the location of a new added Access Point that will improve the positioning. The tool is fully presented and described in the paper and allows the deployment and evaluation of the symbolic positioning in all environments by any use
Principales techniques et technologies de positionnement
No full textNational audienceLe positionnement en milieux difficiles, et en intérieur en particulier, constitue une limitation actuelle forte des systèmes de localisation globaux de type GNSS. De nombreuses solutions tendent à voir le jour, poussées par les industriels du secteur, comme par exemple l'Assisted-GNSS (A-GPS) ou encore les HSGNSS (pour " High Sensitivity GNSS "). Les améliorations en termes de capacité à fournir une position dans des environnements auparavant non couverts par les satellites sont réelles. Cependant, il apparaît aujourd'hui de nouvelles limitations : la limite de détection n'est toujours pas suffisante pour permettre le positionnement en intérieur profond (" deep indoor "), la précision obtenue est dégradée par rapport à l'extérieur, alors qu'il faudrait l'améliorer légèrement, et enfin le temps nécessaire à l'obtention d'une position est parfois de plusieurs secondes. Ces solutions, développées dans le domaine des systèmes de navigation par satellites, ne réclament pas d'avoir recours à une infrastructure : cependant, ici encore, ces approches ne semblent pas permettre une continuité de la fonction de localisation dans des conditions satisfaisantes. Le constat est ainsi le suivant : une solution radio sans infrastructure spécifique, idéale dans l'absolu, n'a pas encore pu être mise en oeuvre dans de bonnes conditions, malgré les efforts importants menés par les industriels des télécommunications et de la navigation
Comparaison de differentes familles logiques utilisees dans la conception de microprocesseurs
No full textSIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
'Positioning and telecommunications' in the world
No full textInternational audienceAmong the numerous technical solutions to positioning, Global Navigation Satellite Systems (GNSS) have a special place. This is mainly due to the fact that they have brought such simplicity of use and low cost that many applications and domains have taken advantage of positioning; for example, civil engineering, the tracking of animals and, of course, car navigation and Location-Based Services (LBS) intended to provide geo-based applications to user
Indoor positioning: technologies and performance
No full textInternational audienceProvides technical and scientific descriptions of potential approaches used to achieve indoor positioning, ranging from sensor networks to more advanced radio-based systems. This book presents a large technical overview of various approaches to achieve indoor positioning. These approaches cover those based on sensors, cameras, satellites, and other radio-based methods. The book also discusses the simplification of certain implementations, describing ways for the reader to design solutions that respect specifications and follow established techniques. Descriptions of the main techniques used for positioning, including angle measurement, distance measurements, Doppler measurements, and inertial measurements are also given.Indoor Positioning: Technologies and Performance starts with overviews of the first age of navigation, the link between time and space, the radio age, the first terrestrial positioning systems, and the era of artificial satellites. It then introduces readers to the subject of indoor positioning, as well as positioning techniques and their associated difficulties. Proximity technologies like bar codes, image recognition, Near Field Communication (NFC), and QR codes are covered—as are room restricted and building range technologies. The book examines wide area indoor positioning as well as world wide indoor technologies like High-Sensitivity and Assisted GNSS, and covers maps and mapping. It closes with the author's vision of the future in which the practice of indoor positioning is perfected across all technologies. This text : Explores aspects of indoor positioning from both theoretical and practical points of viewDescribes advantages and drawbacks of various approaches to positioning. Provides examples of design solutions that respect specifications of tested techniques; Covers infra-red sensors, lasers, Lidar, RFID, UWB, Bluetooth, Image SLAM, LiFi, WiFi, indoor GNSS, and more. Indoor Positioning is an ideal guide for technical engineers, industrial and application developers, and students studying wireless communications and signal processing
Géolocalisation : où en sommes-nous ?
No full textNational audienceCe dossier vise à faire un point sur l'état actuel et les perspectives de la géolocalisation, tant d'un point de vue applicatif que technique. Il tient compte les dernières évolutions dans la communauté de la navigation par satellites (GNSS : Global Navigation Satellite Systems), à savoir le lancement des deux premiers satellites de la future constellation européenne Galileo en novembre dernier, qui sera suivi en septembre prochain par le lancement des deux suivants, ainsi que la disponibilité opérationnelle (avec les 24 satellites nominaux) de la constellation russe GLONASS, sans oublier les lancements réguliers des satellites de la constellation chinoise COMPASS. Bien sûr, les GNSS ne sont pas la seule composante de la géolocalisation : techniquement, certaines limitations de couverture de ces derniers semblent pouvoir être comblées par du Wi-Fi, des systèmes de vision ou l'ajout d'une centrale inertielle
- …
