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Obstacle avoidance techniques for mobile collaborative robots
No full textIl lavoro presentato in questa tesi di dottorato è incentrato sullo sviluppo di tecniche per evitare gli ostacoli per i robot collaborativi mobili, con l'obiettivo di migliorare la sicurezza e l'efficienza della collaborazione uomo-robot negli ambienti industriali. La ricerca esamina il controllo cinematico di manipolatori collaborativi, robot mobili e sistemi ridondanti. L'approccio proposto si basa sul l'integrazione di modelli teorici, simulazioni numeriche e prove sperimentali per convalidare le strategie sviluppate per evitare gli ostacoli.
Un aspetto centrale di questo lavoro riguarda il controllo del l'ambiente di lavoro, del l'operatore e del robot. L'integrazione delle tecniche di evitamento degli ostacoli con un sistema di visione basato su telecamera RGB-D e l'uso del l'apprendimento automatico per rilevare lo scheletro umano sono stati esplorati per i manipolatori, mentre i sensori radar e lidar sono stati utilizzati per i robot mobili.
Il capitolo iniziale fornisce una panoramica completa dei principali problemi di prevenzione degli ostacoli per i robot mobili e collaborativi, analizzando le soluzioni attuali e le sfide nel settore. Successivamente, viene analizzata e testata una tecnica di evitamento degli ostacoli per i manipolatori 6-DOF con ostacoli simulati e reali.
Successivamente, la tesi esplora il miglioramento delle strategie mediante l'implementazione dell'algoritmo su un robot collaborativo ridondante e sfruttando gli eccessi di gradi di libertà per aumentare l'agilità del robot per evitare ostacoli. Vengono poi esplorati i metodi di evitamento degli ostacoli per un robot mobile non oloonómico con trasmissione differenziale, concentrandosi sulle difficoltà associate alla maneggevolezza limitata del robot e alla navigazione sicura in ambienti dinamici. Un altro capitolo descrive le tecniche per evitare gli ostacoli di un robot mobile omnidirezionale con braccio ridondante. Questa soluzione combina la mobilità avanzata e la versatilità del manipolatore, consentendo una navigazione efficiente in ambienti complessi. In collaborazione con il Politecnico di Torino vengono presentati due esempi di simulazione, utilizzando due diversi tipi di robot mobili collaborativi. Successivamente, vengono discussi i metodi di evitamento degli ostacoli per un manipolatore mobile costituito da un braccio 6-DOF e da una base mobile non oloonomica con ruote differenziali. Il capitolo descrive l'algoritmo proposto, seguito dai dati ottenuti in simulazione e conclude con una strategia per evitare gli ostacoli nelle operazioni industriali standard.
Il lavoro si conclude con una sintesi dei risultati ottenuti e alcune proposte per sviluppi futuri. L'approccio innovativo presentato in questa tesi è stato reso possibile grazie alla collaborazione con varie organizzazioni di ricerca e università internazionali. In particolare, la collaborazione con il Politecnico di Torino ha permesso di sperimentare le tecniche di aggiramento degli ostacoli per un robot mobile omnidirezionale a braccio ridondante. L'esperienza acquisita presso l'Istituto di ricerca Joanneum, in Austria, ha contribuito alla definizione di strategie per evitare gli ostacoli per i robot mobili e allo studio degli standard di riferimento. Inoltre, la collaborazione con il laboratorio i-Labs Industry e l'azienda Joytek ha facilitato la sperimentazione in contesti di applicazione reali. La presente tesi rappresenta un contributo significativo allo sviluppo di tecniche avanzate per evitare ostacoli per robot mobili collaborativi, integrando soluzioni teoriche, simulazioni numeriche e prove sperimentali per affrontare le sfide di operazioni sicure ed efficienti in ambienti dinamici e industriali. Le soluzioni proposte potrebbero essere applicate con successo a una vasta gamma di scenari industriali, migliorando l'interazione tra uomo e robot e spianando la strada per future applicazioni innovative nel campo della robotica collaborativa.The work presented in this PhD thesis focuses on the development of obstacle avoidance techniques for mobile collaborative robots, with the aim of improving the safety and efficiency of human-robot collaboration in industrial environments. The research investigates the kinematic control of collaborative manipulators, mobile robots and redundant systems. The proposed approach is based on the integration of theoretical models, numerical simulations and experimental tests to validate the developed obstacle avoidance strategies.
A central aspect of this work concerns the monitoring of the working environment, the operator and the robot. The integration of obstacle avoidance techniques with an RGB-D camera-based vision system and the use of machine learning to detect the human skeleton were explored for manipulators, while radar and lidar sensors were used for mobile robots.
The initial chapter provides a comprehensive overview of the main obstacle avoidance issues for mobile and collaborative robots, analysing current solutions and challenges in the field. Next, an obstacle avoidance technique for 6-DOF manipulators is analyzed and tested with simulated and real obstacles.
Next, the thesis explores the improvement of strategies by implementing the algorithm on a redundant collaborative robot and exploiting the excess degrees of freedom to increase the robot's agility to avoid obstacles. Obstacle avoidance methods for a non-holonomic mobile robot with differential transmission are then explored, focusing on the difficulties associated with the robot's limited manoeuvrability and safe navigation in dynamic environments.
Another chapter describes obstacle avoidance techniques for an omnidirectional mobile robot with a redundant arm. This solution combines the advanced mobility and versatility of the manipulator, allowing efficient navigation in complex environments. Two simulation examples are presented in collaboration with the Polytechnic of Turin, using two different types of mobile collaborative robots. Next, obstacle avoidance methods for a mobile manipulator consisting of a 6-DOF arm and a non-holonomic mobile base with differential wheels are discussed. The chapter describes the proposed algorithm, followed by data obtained in simulation, and concludes with a strategy for obstacle avoidance in standard industrial operations.
The work ends with a summary of the results obtained and some proposals for future developments. The innovative approach presented in this thesis was made possible thanks to the collaboration with various international research organisations and universities. In particular, the collaboration with the Polytechnic of Turin enabled the testing of obstacle avoidance techniques for an omnidirectional mobile robot with a redundant arm. The experience gained at the Joanneum Research Institute, Austria, contributed to the definition of obstacle avoidance strategies for mobile robots and the study of reference standards. Furthermore, the collaboration with i-Labs Industry laboratory and the company Joytek facilitated experimentation in real application contexts.
This thesis represents a significant contribution to the development of advanced obstacle avoidance techniques for mobile collaborative robots, integrating theoretical solutions, numerical simulations and experimental tests to address the challenges of safe and efficient operations in dynamic and industrial environments. The proposed solutions could be successfully applied to a wide range of industrial scenarios, improving the interaction between humans and robots and paving the way for future innovative applications in the field of collaborative robotics
Advanced virtual prototyping of robotic cells using physics-based simulation
Get PDFRobotic cells are complex mechatronic systems whose final performance is determined by the interaction of the control logics with the mechanical behavior of the process. In this context it is fundamental to develop engineering methods and tools for the virtual prototyping of the cells that emulate both contributions. With such mechatronic digital models, it would be possible to replicate the real behavior of the systems and to optimize the cell productivity, up to building complete digital twins. This paper proposes an engineering method to develop realistic Virtual Prototypes of robotic cells including their geometry, operating logic, performance, and physical behavior. A case study on a robotic cell composed of two anthropomorphic robots for the flexible process of automatic assembly of industrial parts is presented to demonstrate the approach
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
Variations on the Author
Get PDF“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
Get PDFWe 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
Non-Holonomic Mobile Manipulator Obstacle Avoidance with Adaptive Prioritization
Get PDFThis paper presents an obstacle avoidance strategy for mobile manipulators consisting of a robotic arm and a base with a non-holonomic differential wheel system. The algorithm makes it possible to avoid obstacles in a dynamic environment, without planning the path a priori. A series of examples are proposed in simulation using Matlab and analyzed to show how the algorithm works if the obstacle interferes with the manipulator or the base. In addition, the possibility of prioritizing the movement of certain parts of the system using the weighted pseudo-inverse matrix is introduced. In this way, it is possible to give movement priority to the base if it is necessary to move the robot over long distances while keeping the manipulator as still as possible. The use of null space to keep the end-effector stationary while it avoids obstacles is also explored, exploiting the system’s redundancy and allowing the rest of the kinematic chain and the mobile base to move accordingly. Finally, current standards are analyzed and a solution is shown that allows the robot to vary its behavior to avoid obstacles depending on the distance to the target point
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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