1,720,956 research outputs found
Intelligent Systems for the Exploration of Structured and Complex Environments
No full textL’attività di ricerca si è concentrata sullo studio, progettazione e realizzazione di sistemi di raccolta dati in ambienti strutturati e complessi. Si è iniziato studiando metodologie e sensori tipicamente utilizzati negli ambienti strutturati, in particolare quello industriale, per poi procedere sull’ambiente sottomarino (ambiente complesso).
Tre sistemi meccatronici innovativi sono stati realizzati. Partendo da un ambiente strutturato è stata sviluppata una stazione automatica per il collaudo dei boiler domestici installata al termine di una catena produttiva. In questo caso studio si è contribuito allo sviluppo e implementazione di tecniche di image processing per l’identificazione dei difetti. La macchina in questo momento lavora autonomamente presso un importante azienda italiana e nelle varie sessioni ha una percentuale di individuazione dei difetti superiore al 90\%, con solo il 3\% di falsi positivi: percentuali di gran lunga migliori a quelle ottenute dagli operatori esperti dell’azienda.
Considerando l’ambiente sottomarino è stato progettato e sviluppato un dispositivo capace di collezionare dati per subacquei al fine di aiutare gli archeologi nell’esplorazione di siti archeologici e ricostruzione 3D. La sfida più importante nello sviluppo è stata implementare l’Unscented Kalman Filter (UKF) risolvente il problema della localizzazione fondendo i dati forniti da Ultra Short Baseline (USBL), Unità di Misura Inerziale (IMU) e ricevitore GPS. Proseguendo nella tematica di raccolta dati in ambienti non strutturati è stato sviluppato un veicolo marino pesciforme autonomo a propulsione ibrida. È stato caratterizzato il sistema di visione del veicolo basato su action camera ed il sistema di controllo dell’orientamento. Il controllore realizzato (Backstepping con osservatore non lineare del disturbo) ha permesso, tramite due motori brushless, la cancellazione del comportamento oscillatorio introdotto dalla propulsione biomimetica.Robotics is related with the development of robotic systems able to move knowing the environment where they must act. The environments diversities have brought researchers developing indoor and outdoor robotic techniques and technologies able to perceive movements and effects at the time arise. This work investigated possible design and implementation of mechatronic structures, able to work in industrial or complex unstructured environments.
As first aspect structured environment and needed sensors has been investigated. The work has been then expanded adding complexity to the aims and reducing the structures faced. During the work, three innovative mechatronic systems have been investigated. The first one regarded the highly structured industrial environment in which an intelligent and semi-autonomous station for testing domestic boilers during the production has been studied.
Considering a more challenging, not structured environment, where optical data need to be gathered with poses information, the author concentrated then on the underwater seabed reconstruction by means of photo cameras carried by divers. The most important challenge in the development of the designed platforms was the Unscented Kalman Filter (UKF) implementation to solve the navigation problem that fuses the data provided by an Ultra Short Baseline (USBL), an Inertial Measurement Unit (IMU) and a receiver for global positioning (GPS).
The work, after considering structured environment reconstruction by means of vision advanced techniques and after facing the situations without positioning structures in the environment, closed with the study of a situation where the robot movement alter the pose but in a way that can be estimated and prevented. An innovative Backstepping controller with a non-linear disturbance observer (NDO) has been designed for the hybrid actuation of the underwater robot under analysis reducing the oscillatory behavior introduced by the biomimetic propulsion
Underwater Simulators Analysis for Digital Twinning
Full text linkThe underwater environment is among Earth's most challenging domains, where failures incur elevated risks and costs for both technology and human endeavors. As a consequence, forecasting the behavior of mechatronic systems through simulation has become increasingly important. Underwater Robotic Simulators (URSs) allow researchers and engineers to safely develop and assess submarine systems. The selection of an appropriate URS from the list of available tools is not trivial. Moreover, the integration of this software with the Digital Twin (DT) concept presents numerous advantages, particularly the ability to link the simulated environment with actual underwater vehicles. This connection is facilitated by performing validation and simulation tests using Software In the Loop (SIL), Model In the Loop, and Hardware In the Loop (HIL) techniques. This paper extensively reviews URSs in the context of both robots and unmanned vehicles in light of the DT paradigm. The article critically examines distinctions among existing URSs, offering valuable insights to aid researchers in selecting the most fitting tool for their specific applications. Additionally, the review explores the practical applications of the identified simulators, categorizing their usage across different fields to illuminate the preferences within the scientific community and showcase prominent case studies
UNIVPM BRAVe: A hybrid propulsion underwater research vehicle
Full text linkIn the last decade, the underwater activities performed by archaeologists and biologists have benefited from scientific research on the guidance, control, and sensory systems of unmanned vehicles. In fact, because underwater sites of interest are often difficult for divers to access, the use of unmanned vehicle technology to conduct surveys could be quite advantageous. In this paper, a novel and partially-biomimetic underwater robot, referred to as BRAVe (Biomimetic Research Autonomous Vehicle), is presented. For documentation purposes, it is equipped with a hybrid propulsion system, which consists of two different types of thrusters. The thrusters are designed to compensate for their reciprocal flaws in order to achieve a more efficient overall system. Specifically, the biomimetic thruster is employed for its superior energetic efficiency, and the horizontal propellers are exploited for accurate maneuvering. While the documentation and 3D reconstruction of the underwater seabed is a consolidated aspect for the authors, the hybrid propulsion system represents the main innovation of the present work. The increase in efficiency achieved by this propulsion system allows the vehicle to perform a thorough and precise documentation of underwater remains within short distances, while exploiting the maximum possible autonomy. This article discusses the details of the development of all the vehicle compartments and their associated characteristics, focusing on the significance of this technology. In addition, the results of 3D reconstructions extrapolated from images taken during real field missions are presented
Underwater position estimation for an underwater vehicle using unscented Kalman filter
No full textMarine researchers need consistent historical and georeferenced data from the marine environment in order to constantly monitor the biological condition of the habitat or to document delicate archeological sites. To overcome the difficulties related to the acquisition of high quantity of worthy data and to the accurate estimation of the position, the development of easy to-use IT tools could certainly help. This article aims to present a tool that can equip different type of underwater vehicles capable of estimating its position during his surveys using its on-board sensors and with the aid of an external buoy. The estimation algorithm is based on the UKF technique and some preliminary simulation results of its performances are presented
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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