1,720,961 research outputs found
Particle Swarm Optimization in SAR-based Method enabling Real-Time 3D Positioning of UHF-RFID Tags
No full textThis paper presents a particle swarm optimization (PSO) in synthetic aperture radar (SAR) methods to enable real-time 3D localization of UHF-RFID tags. The reader antennas are moved through a moving agent (e.g., unmanned aerial vehicle, unmanned ground vehicle, robot) and they collect several phase samples by resembling a synthetic array. Thanks to the PSO approach the 3D matching function of the SAR method can be calculated in a reduced number of points by keeping an acceptable localization error. A numerical analysis demonstrates the method applicability through a comparison with conventional SAR methods based on the exhaustive search (3D dense grid) of the maximum point. Localization performance is investigated when an agent is equipped with a single antenna moving along a 3D trajectory or with two reader antennas at different height running a planar trajectory. Then, an experimental campaign in indoor scenario with an RFID-equipped unmanned ground vehicle shows the method effectiveness in performing real-time 3D positioning with centimeter-order localization error
Advanced RFID-Robot With Rotating Antennas for Smart Inventory in High-Density Shelving Systems
Full text linkA Lightweight SLAM algorithm for indoor autonomous navigation
No full textSimultaneous Localization and Mapping (SLAM) algorithms require huge computational power. Most of the state-of-the-art implementations employ dedicated computational machines which in most cases are off-board the robotic platform. In addition, as soon as the environment become large, the update rate of such algorithms is no more suitable for real-time control. The latest implementations rely on visual SLAM, adopting a reduced number of features. However, these methods are not employable in environments with low visibility or that are completely dark. We present here a SLAM algorithm designed for mobile robots requiring reliable solutions even in harsh working conditions where the presence of dust and darkness could compromise the visibility conditions. The algorithm has been optimized for embedded CPUs commonly employed in light-weight robotic platforms. In this paper the proposed algorithm is introduced and its feasibility as SLAM solution for embedded systems is proved both by a simulated and a real testing scenario
Confined spaces industrial inspection with micro aerial vehicles and laser range finder localization
No full textThis work addresses the problem of semi-automatic inspection and navigation in confined environments. A system that overcomes many challenges at the state of the art is presented. It comprises a multirotor able to inspect an industrial combustion chamber thus working in a GPS-denied environment with poor lighting conditions, in the presence of magnetic and communication disturbances, iron dust and repetitive patterns on the structure walls. The presented system is able to pass through narrow entrances but still capable of acquiring high resolution images and to allow operators to perform inspection of the structures. Starting from the captured data, the system is able to provide a 3D reconstruction of the inspected environment for offline analysis
Towards an autonomous Flying robot for inspections in open and constrained space
No full textA Micro Aerial Vehicle (MAV) capable of navigating in outdoor environments by means of proprioceptive data fusion techniques as well as in indoor and particularly in constrained spaces is here presented. The aim of this system is to inspect failures or procedures correctness inside dangerous areas where human presence should be avoided for long or short time periods. This solution has been oriented toward the specific context of visual inspection of industrial area and it has been tested in a laboratory testbed. In this paper we present hardware and software development of a MAV that can reliably navigate both in outdoor and indoor scenarios making it possible to autonomously change the working location
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Modellazione e simulazione di un alimentatore non convenzionale per applicazioni ferroviarie
No full textCon lo sviluppo dei sistemi di trazione ferroviaria ad alta velocità una delle problematiche più sentite diventa quello della captazione della corrente dalla linea attraverso il pantografo, che realizza un contatto strisciante con la catenaria.
Il miglioramento della captazione è una problematica che si sta affrontando con l’uso di pantografi asserviti e sensori che ne controllano il funzionamento. Da qui nasce l’esigenza di avere un sistema di alimentazione che deve avere le seguenti caratteristiche:
• isolamento galvanico con l’interno del convoglio;
• ridotta manutenzione;
• tensione di uscita di 24 V c.c e potenza nominale non inferiore ai 200 W;
• conforme alle norme IEC 60077, relativa ai requisiti generali per le appa- recchiature elettriche installate a bordo dei rotabili;
• deve modificare in minima parte il cablaggio interno alla locomotiva;
• ingombri limitati.
Dallo studio effettuato presso l’Università di Pisa è stata scelta come fonte di energia l’aria compressa, presente nei treni in quanto usata per il sollevamento del pantografo e per il circuito dei freni
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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