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1
Spani, Giovanni. "Narrare, copiare e leggere la cronaca toscana nel Trecento". [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3290764.
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Thesis (Ph.D.)--Indiana University, Dept. of French and Italian Studies, 2007.Source: Dissertation Abstracts International, Volume: 68-11, Section: A, page: 4703. Adviser: Wayne H. Storey. Title from dissertation home page (viewed May 22, 2008).
2
Piazza, Gianluigi. "Studio microstrutturale e tribologico di leghe leggere prodotte mediante additive manufacturing". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22593/.
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In questo lavoro è stato valutato il comportamento tribologico di leghe prodotte mediante i più diffusi processi di Powder Bed Fusion: SLM (Selective Laser Melting) ed EBM (Electron Beam Melting). Nella prima parte è stata studiata l’influenza di processi di anodizzazione innovativi come PEO (Plasma Electrolytic Oxidation) ed ECO (ElectroChemical Oxidation) sulla lega di alluminio A357 prodotta mediante SLM con due diverse combinazioni di parametri di processo volte ad ottimizzare rispettivamente, la microstruttura (M) e la produttività (P). Nella seconda parte è stato studiato il comportamento tribologico della lega Ti6Al4V prodotta per EBM, in relazione al processo produttivo, alla finitura superficiale e all’orientazione derivante dal processo EBM.
Lo studio tribologico è stato effettuato con prove di strisciamento non lubrificato (geometria pattino-su-cilindro contro acciaio EN 100Cr6), con carichi applicati nell’intervallo 20-60 N, nel caso della lega A357 SLM anodizzata, e di 10 N per la lega Ti6Al4V EBM, in entrambi i casi con velocità di strisciamento di 0,3 m/s.
Nel primo caso i risultati ottenuti hanno dimostrato come entrambi i processi di anodizzazione abbiano migliorato la resistenza ad usura della lega SLM A357 as-built rispetto al substrato non rivestito. Il rivestimento ECO ha dato luogo ad una maggiore resistenza ad usura rispetto al PEO, grazie alle migliori proprietà di coesione ed adesione.
Nel secondo caso i risultati ottenuti hanno evidenziato come il processo EBM sulla lega di Ti6Al4V abbia prodotto resistenza ad usura maggiori rispetto a quella convenzionale, grazie alla maggiore finezza microstrutturale. Nei casi studiati, un aumento di rugosità superficiale ha condotto sempre ad un incremento del tasso d’usura. Al contrario, la sezione di crescita, con orientazione dei grani perpendicolare alla direzione di strisciamento, ha portato ad un’usura minore, rispetto alla sezione a grani equiassici perpendicolare alla direzione di crescita.
3
Albonetti, Pietro. "Analisi del processo di estrusione di leghe leggere con il software Qform: validazione e previsione della microstruttura". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7959/.
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Il gruppo di tecnologie e sistemi di lavorazione del Dipartimento di Ingegneria Industriale, D.I.N, dell’Università di Bologna ha compiuto in collaborazione con il Dipartimento IUL della TU di Dortmund, negli ultimi anni, due campagne sperimentali effettuando processi di estrusione di leghe di alluminio. Nella prima, utilizzando leghe AA6060 e il metodo della visioplasticità, sono stati raccolti dati volti a ricavare le condizioni di attrito di tali processi, tramite confronto con valori ottenuti in simulazioni agli elementi finiti. Nella seconda, utilizzando invece una lega AA6082, è stata valutata la microstruttura al fine di permettere, tramite programmi agli elementi finiti, la determinazione di correlazioni fra variabili che prevedano la dimensione della microstruttura della lega stessa a seguito di lavorazioni per deformazione plastica.
Basandosi quindi su queste prove sperimentali e utilizzando il software “QuantorForm versione 7.2.4”, è stato svolto il lavoro di tesi finalizzato a conseguire i seguenti obiettivi:
• individuare il modello di attrito che si sviluppa nei processi di estrusione analizzati per la lega di alluminio AA6060;
• determinare i parametri di settaggio ottimale del software, confrontando i risultati ottenuti nelle simulazioni con quelli sperimentali;
• determinare le curve che descrivono la dimensione di un grano cristallino di AA6082 in funzione della deformazione;
• implementare come subroutine in Qform, tramite l’utilizzo del linguaggio “Lua”, il modello di microstruttura ottenuto.
4
Mazzon, Ottavia. "Leggere per excerpta : la silloge di estratti conservata nel manoscritto greco Napoli, Biblioteca Nazionale II C 32". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEP014.
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Les intellectuels byzantins ne lisaient pas les œuvres anciennes de manière passive : en lisant, ils avaient toujours le calame à la main pour corriger les fautes du texte, ajouter des notes ou des scholies marginales, pour rédiger des commentaires ou pour en tirer des citations, qu’ils déposaient dans des cahiers de notes. L’étude d’un recueil d’extraits permet de s’approcher en quelque sorte du bureau d’un érudit du passé, de comprendre quels textes il lisait, pourquoi et comment il sélectionnait les passages à citer. Le Neap. II C 32 est un des témoins les plus remarquables de cette pratique de lecture active et il constitue le reflet des intérêts de lecture d’un érudit ou d’un groupe d’érudits, qui avait l’habitude d’annoter les passages les plus intéressants de toutes les œuvres qu’il lisait. Le codex a été écrit par un seul scribe : on peut l’identifier comme Georges Galésiotès, célèbre copiste professionnel qui travailla pour la chancellerie du patriarcat de Constantinople pendant la première moitié du XIVe siècle. Le Neap. II C 32 n’est pas d’un cahier de notes mais il représente la mise au propre de plusieurs brouillons, qui recueillaient plusieurs anthologies d’extraits. L’ordre du contenu du Neapolitanus ne semble pas fortuit, mais il correspond probablement à un projet précis. Le codex peut être divisé en trois sections : la première contient les extraits tirés de la Bible (ff. 1-27) ; la deuxième ceux sélectionnés des ouvrages à sujet religieux (ff. 28-149) ; la troisième est dédiée à la littérature profane. L’analyse critico-textuelle a permis de tracer la place des modèles de certaines anthologies d’extraits dans le cadre de la tradition directe des ouvrages présents dans le codex de NaplesByzantine scholars did not read ancient authors passively: when they read, they always kept a pen in their hands in order to be able to correct eventual mistakes, add notes or scholia, include commentaries. They often employed books to collect interesting quotes, which they annotated separately in handbooks, so that they were ready to be used in the composition of an original work. The study of an anthology of excerpts allows us to somehow approach the writing desk of a scholar of the past: in doing so, it grants us the possibility to understand which texts he read and why, and also analyze the method he used in exploiting his sources. Ms Neap. II C 32 is an exceptional witness of this form of ‘active’ reading. The codex constitutes the reflection of the literary interests of a group of scholars who used to annotate the most interesting passages they found while reading. The codex was written by an only scribe, i.e. George Galesiotes, who worked for the patriarchal chancellery of Constantinople in the first half of the 14th century. Neap. II C 32 is not a scholarly handbook: it is the fair copy of several handbooks. The anthologies of excerpts included in the manuscript have been organized according to a precise project. The codex can thus be divided into three main sections: the first one is dedicated to the Bible (ff. 1-27), the second one to works of religious nature (ff. 28-149), the third one contains profane authors. Textual-critical analysis allows us to situate some of the anthologies included in Neap. II C 32 within the main manuscript tradition of the authors
5
Vandi, Virginia, Lucia Amantini y Francesca Macrelli. "Villa 'la rotonda' dei conti Guidi da Bagno a Savignano sul Rubicone: Un trattato in muratura per leggere il passato e progettare il presente". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/6314/.
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Il primo passo verso un progetto di restauro è costituito dal riconoscimento dell’opera d’arte, che è ciò che spinge al desiderio di trasmetterla al futuro. Nel momento in cui ad un oggetto si riconosce una valenza storica e artistica, questo assume per la collettività un valore che va conservato e potenziato.
Attraverso una approfondita conoscenza delle vicende che hanno interessato la villa dal momento della sua edificazione fino ai giorni nostri, è stato possibile realizzare un progetto che mira alla sua conservazione e alla valorizzazione.
6
Galassi, Daniele y Luca Ferrari. "Moduli sostenibili - retrofit energetico e funzionale di un complesso edilizio residenziale pubblico a bologna, quartiere bolognina". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/9983/.
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In uno scenario in cui il tema dell’emergenza abitativa recita un ruolo da protagonista nelle politiche europee per la casa, il recupero del patrimonio edilizio esistente si pone come una delle strategie più efficaci per rispondere alla problematica dell’abitare sociale. Nel contesto di grave crisi economica ed emergenza energetica che caratterizza la società contemporanea, il valore del retrorfit sta rapidamente trasformando l’approccio progettuale tradizionale, definendo un concetto basilare per la sostenibilità del domani: “fare meglio con meno”.
L’oggetto di questa tesi è la riqualificazione energetica e funzionale di un edificio popolare situato a Bologna, nel quartiere Navile, zona Bolognina.
Il fabbricato si innesta in un isolato a corte che contraddistingue questa zona, caratterizzato da una pianta ad “L” e da sistemi costruttivi tipici della ricostruzione del primo periodo del secondo dopoguerra.
L’ipotesi presentata è il risultato dell’interazione di strategie progettuali mirate alla risoluzione delle problematiche di tipo funzionale ed energetico che affliggono il complesso.
L’intervento è caratterizzato dall’ampio impiego di tecnologie leggere a “secco”, utilizzate sia per l’integrazione dell’edificio con aggiunte volumetriche, che per la realizzazioni di elementi progettuali ex-novo.
7
Colautti, Fabiano. "La lettura come servizio di comunità. Verso un welfare culturale per gli adolescenti". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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Secondo l’International Book Committee leggere è fondamentale per il completo sviluppo del pensiero, della socializzazione e della crescita personale. Durante l’infanzia e l’adolescenza, la lettura deve essere supportata da figure come la scuola, la biblioteca, i propri coetanei e la propria famiglia. Cosa accade però quando questi punti di riferimento vengono meno? Il progetto di tesi ha quindi voluto analizzare il rapporto che gli adolescenti hanno con la lettura, in particolare nel quartiere Barca a Bologna, zona con forte fragilità sociale ed economica.
Dalle ricerche sul campo con gli studenti della scuola media G.Dozza e con le realtà che si occupano di promozione della lettura nel quartiere, sono emerse varie criticità. Infatti, nonostante la presenza della scuola e della biblioteca di quartiere, i giovani hanno bisogno di seguire e praticare la passione della lettura sentendosi stimolati nel farlo. Fondamentale è il supporto e la presenza di una comunità che possa sostenerli in questo processo. Da qui la domanda di ricerca del progetto:
“Come possiamo aiutare gli studenti delle scuole medie - attraverso lo strumento della lettura - a sentirsi protagonisti, inclusi e valorizzati a scuola e nella loro comunità?”
Lettori Innovatori è il servizio che punta a risolvere questa problematica riprendendo il concetto di welfare culturale. Uno dei punti di forza è la rete che si viene a creare attorno e a supporto degli studenti. Infatti, oltre alla scuola e alla biblioteca, gli studenti vengono coinvolti in una più ampia rete composta da esperti della promozione della lettura collaborativa. L’obiettivo è quindi quello di porre gli studenti al centro di un servizio basato sulla lettura durante il quale possono avere l’opportunità di sperimentare nuove pratiche e nuovi strumenti (come il Design Thinking) grazie alle quali possano cimentarsi in una lettura attiva su temi impegnati, responsabilizzandoli e facendoli collaborare tra loro in modo divertente e partecipato.
8
Di, Franco Giovanni. "Motopropulsori ibridi per velivoli leggeri". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23238/.
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L'elaborato propone un'analisi del concetto di motopropulsione ibrida per velivoli leggeri, focalizzandosi sulla motorizzazione per droni, descrivendo, dapprima, le configurazioni principali del sistema ibrido-elettrico e, in seguito, riportando studi di simulazioni e ottimizzazioni.
9
Benfenati, Francesco. "Modello statico a quark degli adroni leggeri". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16789/.
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Lo scopo di questa tesi è quello di trattare il Modello Statico a Quark, o Modello a Quark Costituenti (CQM), in riferimento alla composizione degli adroni leggeri. Questo modello fu proposto indipendentemente da Gell-Mann e Zweig nel 1964 per tentare di spiegare le proprietà che si osservavano degli adroni, ed è oggi il modello maggiormente utilizzato fra quelli efficaci. Come per tutti i risultati della Fisica delle Particelle, anche questo si inserisce in quel contesto di continuo confronto fra Fisica Teorica e Sperimentale che ha contraddistinto in particolare modo questa branca della Fisica. Ci limiteremo a discutere il modello originario, quello del 1964, ovvero quello che comprende solamente i tre quark più leggeri up, down e strange, gli unici noti all’epoca.
Per farlo partiremo nel primo capitolo da un’introduzione generale del Modello Standard e delle caratteristiche che riguardano maggiormente il modello di Gell-Mann e Zweig, seguendo talora un approccio che ricalca la storia scientifica, ovvero prendendo le mosse dalle osservazioni sperimentali, da cui sono seguite poi le deduzioni.
Nel secondo capitolo affronteremo da un punto di vista più tecnico, ma non cadendo nell’eccessivo formalismo matematico, le basi della Teoria dei Gruppi, una teoria che trova molteplici applicazioni nel Modello Standard e da cui esso non può prescindere. In particolare ci limiteremo ai soli aspetti utili ai fini della formulazione del CQM. La trattazione è, dunque, anche un esempio concreto di applicazione alla Fisica della Teoria dei Gruppi.
Nel terzo ed ultimo capitolo, infine, vedremo come il Modello Statico a Quark descrive e classifica gli stati adronici leggeri e le loro proprietà osservate in natura.
10
Cericola, Antonio <1979>. "Valorizzazione di alcani leggeri mediante processi ossidativi". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/1198/.
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Tolochko, Yuliya. "Mondi leggeri – traduzione di un racconto di Tat’jana Tolstaja". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7185/.
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Il presente elaborato è una proposta di traduzione del racconto «Legkie miry» [Mondi leggeri] della scrittrice contemporanea russa Tat’jana Tolstaja. Il racconto venne pubblicato sul sito della rivista «Snob» nel maggio 2013. Il libro di cui fa parte il racconto, invece, è stato presentato nelle maggiori librerie di Mosca e San Pietroburgo nel giugno 2014. «Legkie miry» esce dopo qualche anno dall’ultima pubblicazione dell’autrice e intende, in chiave ironica e non, mostrare la realtà americana degli anni Novanta vista con gli occhi di un’insegnante dell’epoca sovietica. Avventure dolceamare con la casa appena comprata, stanze magiche e mondi leggeri, molteplici sfaccettature di due studenti in particolare, operai che sistemano la casa, o fanno finta. Ma anche lunghi viaggi verso nord dell’America, per raggiungere il posto di lavoro, cantautori russi irrinunciabili compagni di viaggio, mirtilli raccolti e regalati, e l’appena percettibile nostalgia di casa, di Mosca.
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Arduini, Nicola. "Caratterizzazione dei componenti di trazione per un veicolo elettrico leggero". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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L'elaborato si occupa della descrizione degli elementi che costituiscono un veicolo elettrico leggero. Nello specifico sono state inserite e trattate le prove che sono state eseguite sui motori e sul pacco batteria che andranno a fare parte del veicolo elettrico. Successivamente, i dati sperimentali ottenuti sono stati inseriti all'interno di un modello in Simulink, con lo scopo di simulare e conoscere il comportamento del veicolo in varie situazioni di funzionamento.
13
Galassini, Diego. "Impatto delle normative di certificazione sulla progettazione degli elicotteri leggeri". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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In questo elaborato di tesi viene trattato l’impatto delle normative aeronautiche sulla progettazione di prodotti aeronautici e, nello specifico, un caso di certificazione di un elicottero ultraleggero.
Dopo una descrizione del tipo di normative considerate e delle caratteristiche principali dell’elicottero, vengono trattati, in particolare, gli studi compiuti riguardo al telaio e alla trasmissione, due degli aspetti più importanti da considerare nella certificazione di un elicottero leggero nel rispetto delle normative.
Data la sua struttura complessa e le molteplici connessioni tra i componenti, la verifica del telaio è stata effettuata in base ai requisiti previsti dalle normative nel caso di un atterraggio di emergenza.
Per quanto riguarda invece la verifica della trasmissione, sono stati condotti calcoli analitici sui suoi principali componenti, giungendo a verificare la resistenza e la sicurezza degli alberi di trasmissione, degli ingranaggi e della testa del rotore principale.
Infine, sono riportate alcune osservazioni sulle caratteristiche progettuali dell’elicottero, in relazione alle normative da rispettare per la sua commercializzazione.
14
Arnold, Dirk. "Evolution of legged locomotion". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq24085.pdf.
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Baram, Philip. "The six-legged calf /". St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16896.pdf.
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Byl, Katie. "Metastable legged-robot locomotion". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/46362.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 195-215).
A variety of impressive approaches to legged locomotion exist; however, the science of legged robotics is still far from demonstrating a solution which performs with a level of flexibility, reliability and careful foot placement that would enable practical locomotion on the variety of rough and intermittent terrain humans negotiate with ease on a regular basis. In this thesis, we strive toward this particular goal by developing a methodology for designing control algorithms for moving a legged robot across such terrain in a qualitatively satisfying manner, without falling down very often. We feel the definition of a meaningful metric for legged locomotion is a useful goal in and of itself. Specifically, the mean first-passage time (MFPT), also called the mean time to failure (MTTF), is an intuitively practical cost function to optimize for a legged robot, and we present the reader with a systematic, mathematical process for obtaining estimates of this MFPT metric. Of particular significance, our models of walking on stochastically rough terrain generally result in dynamics with a fast mixing time, where initial conditions are largely "forgotten" within 1 to 3 steps. Additionally, we can often find a near-optimal solution for motion planning using only a short time-horizon look-ahead. Although we openly recognize that there are important classes of optimization problems for which long-term planning is required to avoid "running into a dead end" (or off of a cliff!), we demonstrate that many classes of rough terrain can in fact be successfully negotiated with a surprisingly high level of long-term reliability by selecting the short-sighted motion with the greatest probability of success. The methods used throughout have direct relevance to machine learning, providing a physics-based approach to reduce state space dimensionality and mathematical tools to obtain a scalar metric quantifying performance of the resulting reduced-order system.
by Katie Byl.
Ph.D.
17
Fornari, Francesco. "Lightly: un modello per stack undo-redo leggeri per l’editing cooperativo". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21583/.
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Il tema degli undo-redo stack per i Word Processor è un argomento trattato dagli anni ‘70.
Lo scopo di questa tesi è verificare se sia possibile avere un sistema leggero e parlante per salvare le modifiche di un documento.
Lightly prova ad implementare un modello fatto per ottenere non solo un sistema per il salvataggio delle modifiche leggero, ma anche più facile da interpretare per un essere umano, il modello presentato ha una struttura delle modifiche a due livelli di astrazione.
Per implementare il progetto è stato deciso di utilizzare TinyMCE, un Web Word Processor che si presta a creare plugin.
Uno degli altri scopi di lightly è un progetto creato per diventare la base di sviluppo di progetti sull’editing cooperativo che utilizza il modello a due livelli proposto nella tesi.
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Ciacci, Simone <1968>. "Modelli di prestazione ed allenamento speciale della velocità in atletica leggera". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/131/.
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Villa, Nahuel. "Managing Uncertainties in Legged Robots". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAT074.
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Les robots bipède et quadrupède commencent à maîtriser la capacité de marcher de manière dynamique dans la plupart des situations standard. Ceci suggère que l'utilisation commerciale plus répandue de tels robots sera bientôt possible. Toutefois, cela nécessite que des garanties soient fournies concernant sa sécurité et ses performances opérationnelles. Dans les prototypes de recherche, le risque d'échec est généralement limité par l'utilisation de capteurs, d'actionneurs et d'ordinateurs très rapides et précis (et donc très coûteux), ce qui aboutit à des robots nettement trop coûteux pour un usage commercial.La dynamique du centre de masse de ces robots aux pieds de support est instable et, par conséquent, très sensible à toutes les sources d'incertitude. Mais la rapidité et la précision, et donc le coût, des capteurs, des actionneurs et des ordinateurs n’ont jamais été étudiés dans la littérature scientifique existante. Il semble y avoir un manque de quantification précise de l'effet des incertitudes et de la période d'échantillonnage dans le contrôle de l'équilibre des jambes, et l'objectif de ce document est d'initier cette discussion.L'équilibre des robots avec les jambes implique principalement le mouvement de leur CoM par rapport à leurs pieds sur le sol. Par conséquent, nous concentrons notre analyse sur le mouvement du centre de gravité, en considérant que d'autres aspects du mouvement du robot, tels que le mouvement précis de l'articulation du corps entier et le contrôle de la force de contact, sont traités séparément, comme d'habitude dans ce domaine. robotique.Nous avons introduit un modèle de contrôle prédictif (MPC) basé sur des tubes de marche afin de garantir que toutes les restrictions cinématiques et dynamiques sont toujours respectées, même en présence d'incertitudes. Nous pensons que les incertitudes peuvent prendre n'importe quelle valeur entre certaines limites, générant une erreur de suivi qui peut être limitée en conséquence. Nous proposons ici d’analyser le lien entre ces limites: quelle erreur de suivi pouvons-nous espérer pour une certaine incertitude? Naturellement, cela dépend non seulement du type d'incertitude (par exemple, des capteurs ou des actionneurs), mais également de la loi de commande et de sa période d'échantillonnage.Nos résultats sont validés par des expériences et des simulations avec le robot humanoïde Toro à contrôle de couple développé en DLR. Cependant, les dérivations et les résultats mathématiques proposés s’appliquent de manière interchangeable aux robots bipèdes et quadruplesBiped and quadruped robots are beginning now to master the skill of walking dynamically in most standard situations. This suggests that more widespread commercial use of such robots will soon be possible. This requires, however, that guarantees are provided about their safety and operational performance. In research prototypes, the risk of failure is usually contained by using very fast and precise (and therefore very expensive) sensors, actuators and computers, resulting in robots that are clearly too expensive for commercial purposes.The dynamics of the Center of Mass (CoM) of these robots over the support feet is unstable, and therefore very sensitive to all sources of uncertainties. But how fast and precise, and therefore how expensive should the sensors, actuators and computers be has never been investigated in the existing scientific literature. A precise quantification of the effect of uncertainties and sampling period on legged balance control seems to be missing, and it is the goal of this paper to initiate this discussion.The balance of legged robots mostly involves motion of their CoM with respect to their feet on the ground. We therefore focus our analysis on the motion of the CoM, considering that other aspects of the motion of the robot, such as precise whole-body joint motion and contact force control, are handled separately, as usual in this field of robotics.We introduced a tube-based Model Predictive Control (MPC) of walking in order to guarantee that all kinematic and dynamic constraints are always satisfied, even in the presence of uncertainties. We considered that uncertainties can take any value between some bounds, generating some tracking error which can be bounded accordingly. Here, we propose to analyze how these bounds are related: how much tracking error can we expect for a given amount of uncertainty? This naturally depends not only on the kind of uncertainty (e.g. on sensors or actuators), but also on the control law and its sampling period.Our findings are validated in experiments and simulations with the torque-controlled humanoid robot Toro developed at DLR. The proposed mathematical derivations and results apply nevertheless indistinctly to biped and quadruped robots
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ANFLO, FREDRIK. "M8 the Four-legged Robot". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279836.
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In recent times robots are becoming more and more common. They are everywhere. Walking, running, swimming, flying and many of them have much in common with the creatures inhabiting this planet. A lot of it in order to make them appeal more to us, instead of simply being portrayed as stone cold machines. Continuing on the path evolution has laid out before us seems to be a wise decision to make, aspiring to efficiently utilize our knowledge about science and engineering with the vision of improving our future. With the intention to simulate a four legged animal and evaluate the means of interacting with one´s surrounding, a quadruped locomotion system together with two types of sound and voice interacting systems have been assessed. A demonstrator was built to test the real world problems and decide what kind of interacting that is most beneficial. The results indicate that voice commands and speech recognition, rather than sounds from the environment are more practical and robust as a way of interacting with one´s surroundings.På senare tider har robotar blivit mer och mer vanliga. De är överallt. Gående, springande, simmande, flygande och många av dem har mycket gemensamt med de varelser som lever på denna jord. Mycket av detta för att tilltala oss mer, istället för att framstå som enbart iskalla maskiner. Att fortsätta på den väg som evolutionen har lagt framför oss verkar vara ett vist beslut att ta, i strävan efter att effektivt utnyttja våra kunskaper i vetenskap och ingenjörskonst med visionen om att förbättra vår framtid. Med målet att simulera ett fyrbent djur och utvärdera möjligheterna till att interagera med ens omgivning, har ett fyrbent förflyttningssystem tillsammans med två typer av ljud och röstsystem tagits fram. En prototyp kontruerades för att testa de problem som uppstår i den verkliga värden och för att kunna bedöma vilket sätt att interagera som visar vara sig mest fördelaktigt. Resultaten indikerar att röstkommandon och röstigenkänning, snarare än ljuddetektion från omgivningen är mer praktiska och robusta som ett sätt att interagera med sin närmiljö.
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Nilsson, Nadezda. "Familjens bilbarnstol : "Double legged 360"". Thesis, Örebro universitet, Akademin för naturvetenskap och teknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-11253.
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I detta examensarbete tas ett konstruktionsförslag fram på en bilbarnstol vars syfte är att minska ergonomiska problem i samband med installation och användning. Det övergripande målet är säkrare barntransporter. Inledningsvis studeras bilbarnstolar utifrån ett brett perspektiv. En sammanställning av problemen bildar basen för det fortsatta konstruktionsarbetet. En marknadsundersökning genomförs för att kontrollera utbudet av bilbarnstolar i Sverige, vartefter koncept tas fram. Ett koncept bestående av en separat bas med 360 graders rotationsfunktion bedöms mest intressant att vidareutveckla. En digital modell av konstruktionen utvecklas och importeras till DHM mjukvara vartefter en utvärdering sker i form av en OWAS Analys. Slutsatsen blir att konstruktionen potentiellt kan öka säkerheten för barn som transporteras i trafiken. Vidare konstateras att bakåtvända bilbarnstolar är att föredra framför framåtvända samt att det finns mer arbete inom området för såväl fordon som bilbarnstolstillverkare.This graduate work is a construction proposal based on a child safety seat, designed to reduce ergonomic problems related to installation and use. The main goal is safer child transports. Initially child safety seats are investigated from a broad perspective. A summary of the problems form the basis for further design work. A market survey is carried out to control the supply of child safety seats in Sweden, followed by concept development. A concept consisting of a separate base with a 360 degree rotation function is deemed most interesting to develop further. A digital model of the structure gets developed and imported to DHM software by which an evaluation takes place in the form of an OWAS analysis. It is concluded that the construction can potentially improve safety for children during transportation. It’s also noted that rear-facing child safety seats are preferred to forward facing and that there is more work to do in this area for both vehicle and child safety seat manufacturers.
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Casadei, Stefano. "Studio e progettazione di un riduttore per velivolo leggero a motore 1.3 jtd". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4197/.
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Solomon, Gabriel Jerome. "Computer animation of multi-legged creatures". Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/9192.
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Monteiro, Hugo Alexandre Pereira. "Neuromorphic systems for legged robot control". Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7736.
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Locomotion automation is a very challenging and complex problem to solve. Besides the obvious navigation problems, there are also problems regarding the environment in which navigation has to be performed. Terrains with obstacles such as rocks, steps or high inclinations, among others, pose serious difficulties to normal wheeled vehicles. The flexibility of legged locomotion is ideal for these types of terrains but this alternate form of locomotion brings with it its own challenges to be solved, caused by the high number of degrees of freedom inherent to it. This problem is usually computationally intensive, so an alternative, using simple and hardware amenable bio-inspired systems, was studied. The goal of this thesis was to investigate if using a biologically inspired learning algorithm, integrated in a fully biologically inspired system, can improve its performance on irregular terrain by adapting its gait to deal with obstacles in its path. At first, two different versions of a learning algorithm based on unsupervised reinforcement learning were developed and evaluated. These systems worked by correlating different events and using them to adjust the behaviour of the system so that it predicts difficult situations and adapts to them beforehand. The difference between these versions was the implementation of a mechanism that allowed for some correlations to be forgotten and suppressed by stronger ones. Secondly, a depth from motion system was tested with unsatisfactory results. The source of the problems are analysed and discussed. An alternative system based on stereo vision was implemented, together with an obstacle detection system based on neuron and synaptic models. It is shown that this system is able to detect obstacles in the path of the robot. After the individual systems were completed, they were integrated together and the system performance was evaluated in a series of 3D simulations using various scenarios. These simulations allowed to conclude that both learning systems were able to adapt to simple scenarios but only the one capable of forgetting past correlations was able to adjust correctly in the more complex experiments.
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Bhat, Aditya. "Locomotion Trajectory Generation For Legged Robots". Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-theses/1167.
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This thesis addresses the problem of generating smooth and efficiently executable locomotion trajectories for legged robots under contact constraints. In addition, we want the trajectories to have the property that small changes in the foot position generate small changes in the joint target path. The first part of this thesis explores methods to select poses for a legged robot that maximises the workspace reachability while maintaining stability and contact constraints. It also explores methods to select configurations based on a reduced-dimensional search of the configuration space. The second part analyses time scaling strategy which tries to minimize the execution time while obeying the velocity and acceleration constraints. These two parts effectively result in smooth feasible trajectories for legged robots. Experiments on the RoboSimian robot demonstrate the effectiveness and scalability of the strategies described for walking and climbing on a rock climbing wall.
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Reeve, Richard. "Generating walking behaviours in legged robots". Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/30675.
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Many legged robots have been built with a variety of different abilities, from running to hopping to climbing stairs. Despite this however, there has been no consistency of approach to the problem of getting them to walk. Approaches have included breaking down the walking step into discrete parts and then controlling them separately, using springs and linkages to achieve a passive walking cycle, and even working out the necessary movements in simulation and then imposing them on the real robot. All of these have limitations, although most were successful at the task for which they were designed. However, all of them fall into one of two categories: either they alter the dynamics of the robots physically so that the robot, whilst very good at walking, is not as general purpose as it once was (as with the passive robots), or they control the physical mechanism of the robot directly to achieve their goals, and this is a difficult task. In this thesis a novel control model is proposed, inspired by the best walkers and runners around - ourselves - so the controllers produced are based on the vertebrate Central Nervous System. This means that there is a low-level controller which adapts itself to the robot so that, when switched on, it effectively simulates the springs and linkages of the passive robots to produce a walking robot, and this now active mechanism is then controlled by a relatively simple higher level controller. This is the beast of both worlds - we have a robot which is inherently capable of walking, and thus is easy to control like the passive walkers, but also retains the general purpose abilities which makes it so potentially useful.
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Helps, Timothy Nicolas. "Economically optimal designs for legged locomotion". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687425.
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Legged systems are capable of locomotion in a far wider range of environments compared with wheeled or tracked vehicles. Man-made legged locomotion systems are currently economically inferior to wheeled vehicles, tracked vehicles, and legged locomotion systems which exist in nature. In previous research, trajectory optimisation has been applied to legged locomotion systems of a certain design to improve economy, however there has been little work in which the economy of legged locomotion systems is improved through design. This thesis describes the search for economically optimal designs of legged locomotion systems using parametric analysis. An abstract mathematical model of a legged locomotion system was constructed which included an imperfect spring element and electromagnetic actuator. Several actuation strategies were developed which allowed the model to be controlled to perform continuous locomotion. Six performance metrics were identified whose reduction in value implied an increase in economy. The model was simulated performing four locomotion exercises of increasing complexity, beginning with a system oscillating in the absence of gravity and ending with a planar locomotion system. Across these four locomotion exercises, the effect of system architecture, actuation strategy and key system parameters upon economy was determined. Two prototype legged locomotion systems were also constructed for comparison with simulation. It was not possible to simultaneously minimise all performance metrics because minimisation of some performance metrics required choices of system architecture, actuation strategy or system parameter which prevented minimisation of other performance metrics. The economically optimal design of a legged locomotion system was one which minimised the maximum force and peak power requirements of the locomotion system's actuator. Parallel compliance was economically superior to series compliance, which is particularly noteworthy given the comparative rarity of parallel compliance in current man-made legged locomotion systems.
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Liu, Anmin. "The mechanical design of legged robots". Thesis, University of Salford, 2009. http://usir.salford.ac.uk/26779/.
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This thesis has focused on the mechanical design of statically stable multi-legged CLimbing And WAlking Robots(CLAWAR) machines and, since crab-like machines represent an important sub-class, in this thesis they were chosen as the subject of the study. Through the review of leg mechanisms, it is clear that for many years, navigation, gait generation and control, rather than mechanical design, have been the main concerns of many CLAWAR researchers. During the development of prototypes, it has often been assumed that the mechanical design principles are known and the researchers' jobs are simply to apply them. In practice, this is far from the truth, as the performance of existing prototypes testifies. The most common design approach is to copy the geometry of insects and mammals with little or no scientific justification. Although there has been some very good work on leg mechanism design, the relationships between leg design and overall machine layout have been neglected. In this thesis, the design is considered as a whole with no artificial decoupling of leg geometry and overall machine geometry. Furthermore, the design process is treated as a series of coupled optimisation problems. The main achievements and conclusions that have resulted from the research described in this thesis can be summarised as follows: • Based on the review on leg mechanisms, a classification on legged machine layout was proposed; • A clear understanding of the effect of leg configurations and geometric design parameters on the performance of crab-like CLAWAR machines has been achieved. • A novel design methodology that breaks the problem into: a) kinematic design; and b) performance optimisation, was presented. The design methodology is based on satisfying kinematic requirements (constraints) and optimisation of kinetic performance measure, such as minimising the joint torques. • Although the design methodology has only been applied in the 2D case, it has been shown that it could be applied in the 3D case and the necessary analysis methods have been established. • Methods for using foot force distribution as well as design to optimise performance were developed. • Novel reformulations of the Moor-Penrose pseudo-inverse for optimising the foot force distribution in the 3D case were developed, which could be applied in real time control as well as in design.
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Murskyj, Mykola. "Testing the Leggett-Garg inequality with solar neutrinos". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99279.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Physics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 47-48).
One of the fundamental questions in quantum physics is whether measurements reveal pre-existing values. Leggett and Garg derived an inequality that is satisfied by systems featuring both macroscopic realism and non-invasive measurability. The Leggett-Garg Inequality places a quantum-classical limit on a linear combination of correlation functions of a series of measurement outcomes. The flavor oscillations of solar neutrinos provide an interesting way to test the Leggett-Garg inequality, and on an astrophysical length scale. Beginning as electron neutrinos in the solar core, they undergo the Mikheyev-Smirnov-Wolfenstein Effect and exit the sun in either of two mass eigenstates, depending on their energy. Using the neutrino energy to predict the flavor state when it begins traversing the vacuum between the sun and the Earth, we can construct two-time correlation functions of the flavor state at creation, after the MSW effect, and upon detection here on Earth. We can then use these correlation functions to test whether neutrino flavor oscillations obey or violate the Leggett-Garg inequality. Una delle domande fondamentali della fisica quantistica 6 se le misurazioni rivelano valori preesistenti. Leggett e Garg hanno derivato una disuguaglianza che viene soddisfatta da sistemi caratterizzati sia dal realismo macroscopico che dalla misurabilitd non invasiva. La disuguaglianza Leggett-Garg pone un limite quantistico-classico su una combinazione lineare di funzioni di correlazione di una serie di risultati di misura. Le oscillazioni di sapore dei neutrini solari forniscono un modo interessante per testare la disuguaglianza Leggett-Garg, e su una scala di lunghezza astrofisica. Utilizzando l'energia dei neutrini per prevedere lo stato di sapore quando comincia ad attraversare il vuoto tra il sole e la Terra, possiamo costruire funzioni di correlazione due volte dello stato di sapore al momento della creazione, dopo l'effetto MSW, e al rilevamento qui sulla Terra. Possiamo poi utilizzare queste funzioni di correlazione per verificare se oscillazioni di sapore dei neutrini obbediscono o violano la disuguaglianza Leggett-Garg.
by Mykola Murskyj.
S.M.
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Rasia, Carlo <1977>. "La legge applicabile all'arbitrato". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/769/.
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Brito, Frederico Borges de. "Um estudo sobre processos de descoerência em qubits de estado sólido". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277286.
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Orientador: Amir Ordacgi CaldeiraTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
Made available in DSpace on 2018-08-06T02:34:45Z (GMT). No. of bitstreams: 1 Brito_FredericoBorgesde_D.pdf: 5789237 bytes, checksum: 6648aaced89bad6ff2fc57794c0ae747 (MD5) Previous issue date: 2006
Resumo: Esta tese teve como objetivo estudar processos de perda de coerência quântica, chamados de descoerência, em sistemas de matéria condensada eleitos pela literatura como possíveis implementações do bit quântico (qubit). Esta perda de coerência quântica ocorre devido ao inevitável acoplamento do sistema de interesse com o seu ambiente. Como os estados de superposição quântica são a chave para a realização de operações baseadas na lógica quântica, tem-se que tais processos limitam ou até mesmo impedem o uso de determinados sistemas na esperada realização física do computador quântico. Os sistemas de matéria condensada padecem de uma dificuldade maior para se isolar o qubit do seu ambiente, o que acarreta, em geral, na observação de tempos de coerência piores do que os encontrados em seus concorrentes. Por outro lado, a possibilidade de construção de vários qubits acoplados e de manipulação de cada um de modo individual, usando-se técnicas convencionais de engenharia, têm impulsionado esforços nestes tipos de dispositivos. Os sistemas abordados na tese foram: qubits supercondutores contendo junções Josephson; e qubits de pontos quânticos. Para a investigação completa do primeiro tipo tivemos que desenvolver o modelo Caldeira-Leggett para o caso de várias fontes de dissipação acopladas ao qubit. Com a prescrição apresentada aqui, pudemos determinar o número de banhos de osciladores necessários para a correta descrição das fontes, e verificar que as taxas totais de relaxação e de descoerência não são necessariamente as somas das taxas devido a cada fonte individualmente. Além disso, pudemos aplicar o formalismo desenvolvido no estudo de um qubit de uxo em investigação. Para o sistema de pontos quânticos seguimos a linha de determinação do banho efetivo visto pelo grau de liberdade de spin do elétron aprisionado no ponto quântico. Determinada a função espectral efetiva, pudemos encontrar soluções analíticas para a dinâmica do valor esperado para cada uma das componentes de spin s x,y,z. o que permitiu uma análise completa dos efeitos de cada parâmetro físico do sistema. Em ambos os casos, fomos capazes de indicar os melhores regimes de operação de cada qubit, e dar estimativas dos tempos de relaxação e de descoerência
Abstract: The purpose of this thesis was to study the process of loss of quantum coherence, named decoherence, in condensed matter systems cited in the literature as possible candidates for the implementation of a quantum bit (qubit). Decoherence occurs due to the inevitable coupling of the system of interest to its environment. Once the quantum superposition states are the key to perform operations based on quantum logic, these processes limit, or even hinder, the utilization of some of those systems in the physical realization of the quantum computer. Relatively to its competitors, condensed matter systems usually present a higher degree of difficulty as one tries to minimize the coupling between the qubit and its environment, which, generally, worsens its coherence time observations. On the other hand, these devices present advantages which stimulates its study, such as: the possibility of construction of several coupled qubits and the possibility of manipulating each one individually, using conventional engineering techniques. The systems studied in this thesis were: superconducting qubits with Josephson junctions; and electronic spins quantum dots. Aiming at a complete investigation of the first system, we developed the Caldeira-Leggett model for the case of several dissipation sources coupled to the qubit. With the prescription presented here, we determine the number of oscillator baths needed to the correct description of the noise sources, and verify that the total relaxation and decoherence rates are not necessarily the sum of the individual rates relative to each source. Moreover, we applied this formalism to the study of a ux qubit currently under investigation. For the quantum dot qubits, we employed the effective bath approach to treat the dynamics of the spin of the electron localized in the quantum dot. As a result, we found analytical solutions for the dynamics of the average value of each one of the spin components s x,y,z . In both cases, we indicated the best operational regime of each qubit and gave estimates of the relaxation and decoherence times
Doutorado
Física da Matéria Condensada
Doutor em Ciências
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Ridderström, Christian. "Legged locomotion : Balance, control and tools - from equation to action". Doctoral thesis, KTH, Machine Design, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3510.
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This thesis is about control and balance stability of leggedlocomotion. It also presents a combination of tools that makesit easier to design controllers for large and complicated robotsystems. The thesis is divided into four parts.
The first part studies and analyzes how walking machines arecontrolled, examining the literature of over twenty machinesbriefly, and six machines in detail. The goal is to understandhow the controllers work on a level below task and pathplanning, but above actuator control. Analysis and comparisonis done in terms of: i) generation of trunk motion; ii)maintaining balance; iii) generation of leg sequence andsupport patterns; and iv) reflexes.
The next part describes WARP1, a four-legged walking robotplatform that has been builtwith the long term goal of walkingin rough terrain. First its modular structure (mechanics,electronics and control) is described, followed by someexperiments demonstrating basic performance. Finally themathematical modeling of the robots rigid body model isdescribed. This model is derived symbolically and is general,i.e. not restricted to WARP1. It is easily modified in case ofa different number of legs or joints.
During the work with WARP1, tools for model derivation,control design and control implementation have been combined,interfaced and augmented in order to better support design andanalysis. These tools and methods are described in the thirdpart. The tools used to be difficult to combine, especially fora large and complicated system with many signals and parameterssuch as WARP1. Now, models derived symbolically in one tool areeasy to use in another tool for control design, simulation andfinally implementation, as well as for visualization andevaluationthus going from equation to action.
In the last part we go back toequationwherethese tools aid the study of balance stability when complianceis considered. It is shown that a legged robot in astatically balancedstance may actually beunstable. Furthermore, a criterion is derived that shows when aradially symmetricstatically balancedstance on acompliant surface is stable. Similar analyses are performed fortwo controllers of legged robots, where it is the controllerthat cause the compliance.
Keywordslegged locomotion, control, balance, leggedmachines, legged robots, walking robots, walking machines,compliance, platform stability, symbolic modeling
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Erden, Mustafa Suphi. "Six-legged Walking Machine: The Robot-ea308". Phd thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607356/index.pdf.
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The work presented in this thesis aims to make contribution to the understanding and application of six-legged statically stable walking machines in both theoretical and practical levels. In this thesis five pieces of work, performed with and for the three-joint six-legged Robot-EA308, are presented: 1) Standard gaits, which include the well-known wave gaits, are defined and a stability analysis, in the sense of static stable walking, is performed on an analytical level. Various definitions are giventheorems are stated and proved. 2) A free gait generation algorithm with reinforcement learning is developed. Its facilities of stability improvement, smooth speed changes, and adaptation in case of a rear-leg deficiency with learning of five-legged walking are experimented in real-time on the Robot-EA308. 3) Trajectory optimization and controller design is performed for the protraction movement of a three-joint leg. The trajectory generated by the controller is demonstrated with the Robot-EA308. 4) The full kinematic-dynamic formulation of a three-joint six-legged robot is performed with the joint-torques being the primary variables. It is demonstrated that the proposed torque distribution scheme, rather than the conventional force distribution, results in an efficient distribution of required forces and moments to the supporting legs. 5) An analysis of energy efficiency is performed for wave gaits. The established strategies for determination of gait parameters for an efficient walk are justified using the Robot-EA308.
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au, shiqi peng@woodside com y Shiqi Peng. "A Biologically Inspired Four Legged Walking Robot". Murdoch University, 2006. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20070115.113710.
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This Ph.D. thesis presents the design and implementation of a biologically inspired
four-phase walking strategy using behaviours for a four legged walking robot. In
particular, the walking strategy addresses the balance issue, including both static and
dynamic balance that were triggered non-deterministically based on the robots realtime interaction with the environment. Four parallel Subsumption Architectures
(SA) and a simple Central Pattern Producer (CPP) are employed in the physical
implementation of the walking strategy. An implementation framework for such a
parallel Subsumption Architecture is also proposed to facilitate the reusability of the
system. A Reinforcement Learning (RL) method was integrated into the CPP to
allow the robot to learn the optimal walking cycle interval (OWCI), appropriate for
the robot walking on various terrain conditions. Experimental results demonstrate
that the robot employs the proposed walking strategy and can successfully carry out
its walking behaviours under various experimental terrain conditions, such as flat
ground, incline, decline and uneven ground. Interactions of all the behaviours of the
robot enable it to exhibit a combination of both preset and emergent walking
behaviours.
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Peng, Shiqi. "A biologically inspired four legged walking robot". Peng, Shiqi (2006) A biologically inspired four legged walking robot. PhD thesis, Murdoch University, 2006. http://researchrepository.murdoch.edu.au/255/.
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This Ph.D. thesis presents the design and implementation of a biologically inspired four-phase walking strategy using behaviours for a four legged walking robot. In particular, the walking strategy addresses the balance issue, including both static and dynamic balance that were triggered non-deterministically based on the robot's realtime interaction with the environment. Four parallel Subsumption Architectures (SA) and a simple Central Pattern Producer (CPP) are employed in the physical implementation of the walking strategy. An implementation framework for such a parallel Subsumption Architecture is also proposed to facilitate the reusability of the system. A Reinforcement Learning (RL) method was integrated into the CPP to allow the robot to learn the optimal walking cycle interval (OWCI), appropriate for the robot walking on various terrain conditions. Experimental results demonstrate that the robot employs the proposed walking strategy and can successfully carry out its walking behaviours under various experimental terrain conditions, such as flat ground, incline, decline and uneven ground. Interactions of all the behaviours of the robot enable it to exhibit a combination of both preset and emergent walking behaviours.
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Goulding, John. "The Single-Track Three Legged Mobile Robot". Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/312548.
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Unstable legged robots fall over without active stabilization, typically by repositioning the feet to maintain/regain stability of balance. This dissertation concerns the development of a Single-Track Three Legged Mobile Robot (ST3LMR) and control system. A proof-of-concept was demonstrated through digital simulation and experimentation with physical prototypes. The ST3LMR comprises a body and three articulated legs arranged in a narrow profile, one behind the other, to walk and maneuver along narrow trails and paths. The ST3LMR walks by placing successive footfalls in a generally single-track or in-line fashion. It achieves the form and function of a motorcycle but with the added benefit of legs and robotic control. That is, the feet are stationary with respect to footholds during the support period, thus eliminating the drawback of wheels, which require continuous support (especially when used in rugged terrain). By always having at least two feet on the ground, the ST3LMR is inherently stable in the pitch axis (in the forward/backward direction of motion), which allows for decoupling stability of balance control to only the roll axis (in the left/right direction).Suggested by recent developments in high-performance computing, walking robot locomotion and stabilization is considered from a new perspective, that of the Monte Carlo (MC) method. A high-speed MC simulation is used in a model-predictive control system to determine footholds that provide stability of balance. Stability of balance, maneuverability, and control is demonstrated through experimental results from physical prototypes and a simple digital simulation of an impulse response, avoidance maneuver, and leaning-into-the-turn maneuver.
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Miao, Shan. "Six legged walking machine gait and design". Thesis, University of Salford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300830.
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Golubovic, Dragos. "Evolving walking behaviours for Sony legged robots". Thesis, University of Essex, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416717.
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Hauser, Kris. "Motion planning for legged and humanoid robots /". May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Angle, Colin. "Genghis, a six legged autonomous walking robot". Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14531.
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Zeglin, Garth J. (Garth John). "Uniroo--a one legged dynamic hopping robot". Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13052.
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Enoch, Alexander Michael. "Legged robotic locomotion with variable impedance joints". Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20436.
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Humans have a complex musculoskeletal arrangement which gives them great behavioural flexibility. As well as simply moving their legs, they can modulate the impedance of them. Variable impedance has become a large field in robotics, and tailoring the impedance of a robot to a particular task can improve efficiency, stability, and potentially safety. Locomotion of a bipedal robot is a perfect example of a task for which variable impedance may provide such advantages, since it is a dynamic movement which involves periodic ground impacts. This thesis explores the creation of two novel bipedal robots with variable impedance joints. These robots aim to achieve some of the benefits of compliance, while retaining the behavioural flexibility to be truly versatile machines. The field of variable impedance actuators is explored and evaluated, before the design of the robots is presented. Of the two robots, BLUE (Bipedal Locomotion at the University of Edinburgh) has a 700mm hip rotation height, and is a saggital plane biped. miniBLUE has a hip rotation height of 465mm, and includes additional joints to allow hip adduction and abduction. Rapid prototyping techniques were utilised in the creation of both robots, and both robots are based around a custom, high performance electronics and communication architecture. The human walking cycle is analysed and a simple, parameterised representation developed. Walking trajectories gathered from human motion capture data, and generated from high level gait determinants are evaluated in dynamic simulation, and then on BLUE. With the robot being capable of locomotion, we explore the effect of varying stiffness on efficiency, and find that changing the stiffness can have an effect on the energy efficiency of the movement. Finally, we introduce a system for goal-based teleoperation of the robots, in which parameters are extracted from a user in a motion capture suit and replicated by the robot. In this way, the robot produces the same overall locomotion as the human, but with joint trajectories and stiffnesses that are more suited for its dynamics.
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Fisher, Callen. "Trajectory Optimisation Inspired Design for Legged Robotics". Doctoral thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33715.
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Control of legged robots is a non-trivial task, especially when looking at aperiodic (non-steadystate) manoeuvres such as rapid acceleration and deceleration. Observing nature, animals are seen to effortlessly perform these rapid transient manoeuvres, however, robust walking is still considered a complex task in the robotics literature. For robots to successfully explore the unknown world outside of the laboratory environment, these transient manoeuvres need to be thoroughly understood and mastered. As controlling and designing legged robots is an extremely complex task, this thesis argues that trajectory optimisation methods can be employed to make various aspects of design more tractable. First trajectory optimisation methods were employed to determine how legged robots should accelerate. In nature animals are seen to leap straight into the desired gait, however, in the robotics literature, robots often perform multiple discrete gait transitions, or accelerate extremely slowly. The results of the study revealed that the optimal method to accelerate was to launch straight into the desired gait (for both bipeds and quadrupeds), with a sliding mass template model emerging for all results. Another discrepancy between the literature and nature is that animals have active spines which have been shown to aid in rapid locomotion tasks. In the robotics literature a number of spines exists, however, which is the optimal morphology for transient manoeuvres? Using Monte Carlobased trajectory optimisation methods, the rigid, revolute and prismatic spine morphologies were compared, with results showing the prismatic spine was the optimal configuration for long-time-horizon tasks. Due to transient locomotion requiring accurate and complex whole-body models, resulting in computationally expensive optimisation problems, an “optimisation-inspired” approach (akin to “bioinspiration”) was taken to identify heuristics and trends for a monopod robot. Initially, optimal trajectories for a two link leg monopod were analysed. Interestingly, during the stance phase, the axial force of the leg behaved in a “bang-bang” like fashion with fine hip torque control. Furthermore the aerial phase showed correspondence to the popular Raibert style controller. This resulted in the development of a hybrid pneumatic-electric monopod robot as a test-bed. Trajectories were then optimised for the robot to determine if these heuristics held. From these results, a stance phase PD controller for the hip actuator was developed and simulated under disturbances to test robustness. The resulting controller and heuristic was successfully tested on the platform, performing a long-time-horizon motion, which included transient phases of acceleration and deceleration.
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Tsujita, Katsuyoshi. "Research on locomotion control of legged robots". 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/145346.
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Michelsen, Trond G. "Kunnskapsdeling mellom medarbeiderne i en organisasjon som skal legges ned. : En feltstudie fra en spansk bank som skal legges ned". Thesis, Högskolan i Borås, Institutionen Biblioteks- och informationsvetenskap / Bibliotekshögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-17708.
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The study examines a spanish bank during downsizing and partial closeure and how this affect the knowledge sharing between co-workers. The employees know that they will loose their job within a year and the study looks on various factors that influences factual knowledge sharing in the organisation. Factors include willingness,communication and time as well as how the organisations structure might influence on the sharing of knowledge.The result of the study shows that there is no radical change between how the co-workers share knowledge under the crises as compared to before the crises emerged. However, contrary to previous studies, this study shows that the co-workers experience to have more time to fulfil their working duties now as compared to before the crises.Program: Magisterutbildning i strategisk information och kommunikation
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Haleem, Kirolos. "Comprehensive Analytical Investigation of the Safety of Unsignalized Intersections". Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2741.
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According to documented statistics, intersections are among the most hazardous locations on roadway systems. Many studies have extensively analyzed safety of signalized intersections, but did not put their major focus on the most frequent type of intersections, unsignalized intersections. Unsignalized intersections are those intersections with stop control, yield control and no traffic control. Unsignalized intersections can be differentiated from their signalized counterparts in that their operational functions take place without the presence of a traffic signal. In this dissertation, multiple approaches of analyzing safety at unsignalized intersections were conducted. This was investigated in this study by analyzing total crashes, the most frequent crash types at unsignalized intersections (rear-end as well as angle crashes) and crash injury severity. Additionally, an access management analysis was investigated with respect to the different median types identified in this study. Some of the developed methodological techniques in this study are considered recent, and have not been extensively applied. In this dissertation, the most extensive data collection effort for unsignalized intersections was conducted. There were 2500 unsignalized intersections collected from six counties in the state of Florida. These six counties were Orange, Seminole, Hillsborough, Brevard, Leon and Miami-Dade. These selected counties are major counties representing the central, western, eastern, northern and southern parts in Florida, respectively. Hence, a geographic representation of the state of Florida was achieved. Important intersections' geometric and roadway features, minor approach traffic control, major approach traffic flow and crashes were obtained. The traditional negative binomial (NB) regression model was used for modeling total crash frequency for two years at unsignalized intersections. This was considered since the NB technique is well accepted for modeling crash count data suffering from over-dispersion. The NB models showed several important variables affecting safety at unsignalized intersections. These include the traffic volume on the major road and the existence of stop signs, and among the geometric characteristics, the configuration of the intersection, number of right and/or left turn lanes, median type on the major road, and left and right shoulder widths. Afterwards, a new approach of applying the Bayesian updating concept for better crash prediction was introduced. Different non-informative and informative prior structures using the NB and log-gamma distributions were attempted. The log-gamma distribution showed the best prediction capability. Crash injury severity at unsignalized intersections was analyzed using the ordered probit, binary probit and nested logit frameworks. The binary probit method was considered the best approach based on its goodness-of-fit statistics. The common factors found in the fitted probit models were the logarithm of AADT on the major road, and the speed limit on the major road. It was found that higher severity (and fatality) probability is always associated with a reduction in AADT, as well as an increase in speed limit. A recently developed data mining technique, the multivariate adaptive regression splines (MARS) technique, which is capable of yielding high prediction accuracy, was used to analyze rear-end as well as angle crashes. MARS yielded the best prediction performance while dealing with continuous responses. Additionally, screening the covariates using random forest before fitting MARS model was very encouraging. Finally, an access management analysis was performed with respect to six main median types associated with unsignalized intersections/access points. These six median types were open, closed, directional (allowing access from both sides), two-way left turn lane, undivided and mixed medians (e.g., directional median, but allowing access from one side only). Also, crash conflict patterns at each of these six medians were identified and applied to a dataset including median-related crashes. In this case, separating median-related and intersection-related crashes was deemed significant in the analysis. From the preliminary analysis, open medians were considered the most hazardous median type, and closed and undivided medians were the safest. The binomial logit and bivariate probit models showed significant median-related variables affecting median-related crashes, such as median width, speed limit on the major road, logarithm of AADT, logarithm of the upstream and downstream distances to the nearest signalized intersection and crash pattern. The results from the different methodological approaches introduced in this study could be applicable to diagnose safety deficiencies identified. For example, to reduce crash severity, prohibiting left turn maneuvers from minor intersection approaches is recommended. To reduce right-angle crashes, avoiding installing two-way left turn lanes at 4-legged intersections is essential. To reduce conflict points, closing median openings across from intersections is recommended. Since left-turn and angle crash patterns were the most dominant at undivided medians, it is recommended to avoid left turn maneuvers at unsignalized intersections having undivided medians at their approach. This could be enforced by installing a left-turn prohibition sign on both major and minor approaches.Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering PhD
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Dall'Alpi, Daniele. "Gait generation for a six-legged walking machine". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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This thesis focuses on the study of a six-legged walking machine. It consists of a chassis and six legs with three revolute joints each. Instead of a feet, each leg features a wheel, so that it is not only capable of walking but also driving. Furthermore, the robot is equipped with a 5-DOF arm and a gripper. The robot uses an Arduino platform for low-level control of the drives and an x86-64 computer for high-level tasks such as flow control, image processing, navigation or obstacle recognition.
The aim of this work is to implement a gait generation algorithm in a six-legged walking machine and simulate the behaviour of the system. First of all, a thorough survey of literature considering static gait of multi-legged walking machines, planning-based and reactive controllers needs to be conducted. After deciding on a gait generation approach, the corresponding algorithms will be adapted to the specifications of the robot and implemented for simulation.
A kinematic model of the robot is derived. A dynamic model is not needed since we focus on gait planning for statically stable walking.
There are two possible modes of operation: remote controlled and autonomous. In the former mode, the robot is controlled from a base station with a gamepad and movement commands are transmitted to the mobile robot. We think that the easiest way to control the robot is to assign the curvature of the desired path (turning radius) and the orientation of the robot with respect to the motion direction (crab angle). In fact, only two inputs are needed in order to perform any general trajectory.
In order to achieve the best result for the gait planning, some different procedures are developed. Their performances are compared considering both the stability of the motion and the computation time.
Finally, once the gait is generated, inverse kinematics is used to determine motors motion law.
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Teo, Jason T. W. Information Technology & Electrical Engineering Australian Defence Force Academy UNSW. "Pareto multi-objective evolution of legged embodied organisms". Awarded by:University of New South Wales - Australian Defence Force Academy. School of Information Technology and Electrical Engineering, 2003. http://handle.unsw.edu.au/1959.4/38682.
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The automatic synthesis of embodied creatures through artificial evolution has become a key area of research in robotics, artificial life and the cognitive sciences. However, the research has mainly focused on genetic encodings and fitness functions. Considerably less has been said about the role of controllers and how they affect the evolution of morphologies and behaviors in artificial creatures. Furthermore, the evolutionary algorithms used to evolve the controllers and morphologies are pre-dominantly based on a single objective or a weighted combination of multiple objectives, and a large majority of the behaviors evolved are for wheeled or abstract artifacts. In this thesis, we present a systematic study of evolving artificial neural network (ANN) controllers for the legged locomotion of embodied organisms. A virtual but physically accurate world is used to simulate the evolution of locomotion behavior in a quadruped creature. An algorithm using a self-adaptive Pareto multi-objective evolutionary optimization approach is developed. The experiments are designed to address five research aims investigating: (1) the search space characteristics associated with four classes of ANNs with different connectivity types, (2) the effect of selection pressure from a self-adaptive Pareto approach on the nature of the locomotion behavior and capacity (VC-dimension) of the ANN controller generated, (3) the effciency of the proposed approach against more conventional methods of evolutionary optimization in terms of computational cost and quality of solutions, (4) a multi-objective approach towards the comparison of evolved creature complexities, (5) the impact of relaxing certain morphological constraints on evolving locomotion controllers. The results showed that: (1) the search space is highly heterogeneous with both rugged and smooth landscape regions, (2) pure reactive controllers not requiring any hidden layer transformations were able to produce sufficiently good legged locomotion, (3) the proposed approach yielded competitive locomotion controllers while requiring significantly less computational cost, (4) multi-objectivity provided a practical and mathematically-founded methodology for comparing the complexities of evolved creatures, (5) co-evolution of morphology and mind produced significantly different creature designs that were able to generate similarly good locomotion behaviors. These findings attest that a Pareto multi-objective paradigm can spawn highly beneficial robotics and virtual reality applications.
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Li, Lijun. "Vertical control for an one-legged hopping robot". online version, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1193422512.
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Vallarino, Moncada Adriana. "Sibling rivalry in black-legged kittiwakes (Rissa tridactyla)". Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/200/.
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Chicks of several species compete with their siblings for parental provisioning of resources and care. This competition is mainly manifested by begging or food hoarding and in only few species, as in the black-legged kittiwake (Rissa tridactyla) direct aggression between the offspring is present.. It has been proposed that the degree of asymmetries between the members of a brood influence the severity and outcome of this conflict. Several inequalities between the offspring have been identified (e.g. age, size, egg quality). First- hatched chicks (A) are older, larger and hatch from a different quality egg and size than second- hatched chicks (B). These inequalities provide different advantages to the chicks within a brood but their influence in sibling rivalry have not been widely tested. In the present thesis egg components of A and B eggs were analysed, comparisons of behaviour, survival and growth of chicks in two different years were made and egg size and quality were experimentally manipulated in order to test their importance in the sibling rivarly outcome of the black-legged kittiwake. In chapter II egg composition analyses of A- and B- eggs within a clutch were made. It was found that mothers allocated more carotenoids and less testosterone to A- eggs, while corticosterone, lipid and protein content did not differ, although A- eggs were 4% larger than B- eggs. In chapter III comparisons of behaviour, growth and survival between two environmentally different years were made. 2004 was a year with poor quality food whilst 2005 was a year with good food quality. The majority of second-hatched chicks in 2004 died before reaching 10 days of age and were all dead before 15 days while in 2005, more than 80% of second-hatched chicks fledged. Same behaviours were performed by A and B chicks in both years but the behavioural patterns did: aggression increased with age in 2004 while begging and feeding decreased in A and B chicks; these behaviours did not change with age in 2005. In chapter IV the influence of egg size on sibling rivalry was experimentally tested by eliminating age and egg quality differences within a brood and manipulating only the egg size differences. Comparisons of survival, growth and behaviour were made between experimental and control broods in which all the natural asymmetries were present. Differences in egg size determined which chick became dominant but these differences did not change the brood behaviour. Furthermore, experimental broods showed very different behaviour from control broods and the frequency of aggression was different between experimental broods formed by A- or B- eggs. In order to test if eggs are adapted for their hatching position, in chapter V an experimental manipulation of the brood composition was carried out and one of the clutch eggs’ was swapped to make it hatch in a different position from the one it was made to hatch. The natural asymmetries in age and egg size were maintained. Broods with two first-laid eggs were less aggressive than control broods and than broods with two second-laid eggs. If A- and B- chicks are specifically made for their hatching position, their stress response should differ when they were artificially made to hatch on the same position and exposed to a stressor. This was tested on chapter VI and it was found that second hatched chicks from A- and B eggs did not differ on their stress response when facing a handling-stress protocol. On each year, natural broods fledged in higher proportion than experimental ones, which indicates that asymmetries within a brood are adaptive. It seems that eliminating within brood asymmetries is costly for the parents and perhaps these differences are optimal for maintaining a high efficiency index for the parents in terms of the amount of investment and the number of fledged chicks. Thus apparently, the main asymmetry influencing sibling rivalry is the difference in age of the offspring caused by hatching asynchronously.