116 research outputs found
Ma Huan (original author), Wan Ming (ed.) Ming chaoben " Yingya shenglan " jiaozh
No full textPtak Roderich. Ma Huan (original author), Wan Ming (ed.) Ming chaoben " Yingya shenglan " jiaozh. In: Archipel, volume 71, 2006. Autour de la peinture à Java. Volume II. pp. 240-244
Sparse robot swarms: Moving swarms to real world applications
No full textRobot swarms are groups of robots that each act autonomously based on only local perception and coordination with neighboring robots. While current swarm implementations can be large in size (e.g., 1,000 robots), they are typically constrained to working in highly controlled indoor environments. Moreover, a common property of swarms is the underlying assumption that the robots act in close proximity of each other (e.g., 10 body lengths apart), and typically employ uninterrupted, situated, close-range communication for coordination. Many real world applications, including environmental monitoring and precision agriculture, however, require scalable groups of robots to act jointly over large distances (e.g., 1,000 body lengths), rendering the use of dense swarms impractical. Using a dense swarm for such applications would be invasive to the environment and unrealistic in terms of mission deployment, maintenance and post-mission recovery. To address this problem, we propose the sparse swarm concept, and illustrate its use in the context of four application scenarios. For one scenario, which requires a group of rovers to traverse, and monitor, a forest environment, we identify the challenges involved at all levels in developing a sparse swarm—from the hardware platform to communication-constrained coordination algorithms—and discuss potential solutions. We outline open questions of theoretical and practical nature, which we hope will bring the concept of sparse swarms to fruition.</p
Universal Probability Distribution for the Wave Function of a Quantum System Entangled with Its Environment
No full textA quantum system (with Hilbert space H1) entangled with its environment (with Hilbert space H2) is usually not attributed a wave function but only a reduced density matrix ρ1. Nevertheless, there is a precise way of attributing to it a random wave function ψ1, called its conditional wave function, whose probability distribution μ1 depends on the entangled wave function ψ∈H1⊗H2 in the Hilbert space of system and environment together. It also depends on a choice of orthonormal basis of H2 but in relevant cases, as we show, not very much. We prove several universality (or typicality) results about μ1, e.g., that if the environment is sufficiently large then for every orthonormal basis of H2, most entangled states ψ with given reduced density matrix ρ1 are such that μ1 is close to one of the so-called GAP (Gaussian adjusted projected) measures, GAP(ρ1). We also show that, for most entangled states ψ from a microcanonical subspace (spanned by the eigenvectors of the Hamiltonian with energies in a narrow interval [E,E+δE]) and most orthonormal bases of H2, μ1 is close to GAP(tr2ρmc) with ρmc the normalized projection to the microcanonical subspace. In particular, if the coupling between the system and the environment is weak, then μ1 is close to GAP(ρβ) with ρβ the canonical density matrix on H1 at inverse temperature β=β(E). This provides the mathematical justification of our claim in [J. Statist. Phys. 125:1193 (2006), http://arxiv.org/abs/quant-ph/0309021] that GAP measures describe the thermal equilibrium distribution of the wave function.Peer reviewe
Theodor Fontane, Julius Roderich Benedix and the royal theater in Berlin
No full textTheodor Fontane, Julius Roderich Benedix und das königliche Schauspielhaus in BerlinHeike JantschnerDiese Arbeit beschäftigt sich mit Theodor Fontane als Theaterkritiker für die Vossische Zeitung und Julius Roderich als Lustspielautor. Die Kernfragen der Arbeit lauten: Wer war der heute kaum noch bekannte Roderich Benedix? Warum waren seine Werke zu seinen Lebzeiten und Jahrzehnte postum noch so beliebt auf deutschen Bühnen? Worin liegt der Grund für dessen Beliebtheit? Um diesen Fragen nachzugehen, werden Theodor Fontanes Theaterkritiken vom königlichen Schauspielhaus in Berlin allgemein betrachtet, daraufhin seine Kritiken über Benedix genau analysiert. Daraus ergab sich, dass Benedix zu den beliebtesten deutschen Bühnenautoren seiner Zeit zählte. Seine Motive, Figuren sowie seine Komik waren neben den damals aufkommenden französischen Lustspielen und später dem Naturalismus eine erfrischende, harmlose, deutsche Alternative.Theodor Fontane, Julius Roderich Benedix and the royal theater in BerlinHeike JantschnerThe present work deals with the combined analysis of Theodor Fontane as a theater critic and Julius Roderich Benedix as a comedy author, respectively. The core issues of this volume can be summarized as follows: Who was this today rarely known man called Roderich Benedix? Why was his work during his lifetime as well as over decades posthumous that famous on German scenes? To respond to these raised questions, the critics of Theodor Fontane during his work at the royal theater of Berlin were, first of all, examined on a general basis followed by a detailed analysis of his critics regarding Benedix. This leads to the conclusion that Benedix ranked among the most popular scene writers at that time. The motives, characters created by him as well as his inimitable comic were, beside the arising comics from France and the upcoming naturalism, refreshing, harmless alternatives made in Germany.vorgelegt von Heike JantschnerAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersZsfassungen in dt. und engl. SpracheGraz, Univ., Masterarb., 2015 2084
Switched Lyapunov based and model predictive control strategies for aggregation of mobile robots
No full textLAUREA MAGISTRALEQuesta tesi si occupa della progettazione di strategie di aggregazione di una rete di robot mobili caratterizzati da una dinamica vincolata. Inspirati da un precedente lavoro in letteratura, è stata considerata una rete di robot di forma circolare distribuiti su un piano ed in grado di eseguire solo due movimenti, uno di rotazione sul posto e uno di rototraslazione tale da descrive un percorso circolare. In letteratura questi movimenti dipendono dalle informazioni fornite da un sensore di prossimità, mentre i valori di velocità per ciascuna ruota sono determinati creando una griglia e selezionandoli all’interno di uno spazio delle azioni di controllo. L'obiettivo di questo lavoro è stato invece quello di riformulare questa architettura di controllo e sviluppare nuove soluzioni al problema di aggregazione sulla base della teoria dei sistemi switched e del controllo predittivo (MPC). Per ottenere questa formulazione è stato rimosso il requisito del sensore di prossimità, sfruttando invece una struttura centralizzata per costruire una legge di controllo in feedback basata su relazioni geometriche. Facendo poi riferimento ai sistemi switched, sono sono state proposte due strategie di controllo basate sul concetto di funzione di controllo di Lyapunov (CLF). Inoltre, sono state previste la verifica di collisioni e una strategia di avoidance, inserendo questi obiettivi come vincoli di un problema di controllo ottimo (OCP), risolto progettando un controllo predittivo di tipo switched. (SMPC). L'efficacia dei controllori proposti è stata dimostrata da diverse simulazione e anche da esperimenti eseguiti sulla piattaforma remota Robotarium.This thesis deals with the design of aggregation strategies of a network of mobile wheeled robots with constrained dynamics. Starting from a similar setup taken from a previous research work in the literature, a network of circular robots distributed in a plane, performing only two motions (rotation on the spot and roto-translation describing a circular path), is considered. In the literature such motions depend on a proximity sensor reading, while the velocity values for each wheel in both states are determined through a grid search over a space of controllers. The goal of this work is instead to recast such architecture into a new control framework and develop novel solutions to the problem of aggregation relying on switched systems and Model Predictive Control (MPC) theory. In order to do this, first the sensor requirement is removed, exploiting the centralized structure to build a state feedback control law based on geometric relationships. Making reference to the switching systems theory, two control strategies are then proposed relying on the notion of Control Lyapunov Function (CLF) for stabilization. Finally, the tracking and collision avoidance are also formulated as an Optimal Control Problem (OCP), solved by designing a Switching Model Predictive Control (SMPC). The effectiveness of the proposed controllers are demonstrated by a series of simulations as well as experiments on the Robotarium remote platform
Segregation in swarms of mobile robots based on the Brazil nut effect
No full textWe study a simple algorithm inspired by the Brazil nut effect for achieving segregation in a swarm of mobile robots. The algorithm lets each robot mimic a particle of a certain size and broadcast this information locally. The motion of each particle is controlled by three reactive behaviors: random walk, taxis, and repulsion by other particles. The segregation task requires the swarm to self- ranked by particle size (e.g., annular structures or stripes). Using a physics-based computer simulation, we study the segregation performance of swarms of 50 mobile robots. The robots represent particles of three different sizes. We first analyze the problem of how to combine the basic behaviors so as to minimize the percentage of errors in rank. We then show that the system is very robust with respect to noise on inter-robot perception and communication. For a noise-level of 50%, the mean percentage of errors in rank is 1%. Moreover, we investigate a simplified version of the control algorithm, which does not rely on communication. Finally, we show that the mean percentage of errors in rank decreases exponentially as the particles’ size ratio increases. As the error is bounded, one can achieve 100% error-free segregation. The reduction in error, however, comes at the expense of an increase in the required sensing/communication range.LSR
Self-assembling robots
No full textWe look at robotic systems made of separate discrete components that, by self-assembling, can organize into physical structures of growing size. We review 22 such systems, exhibiting components ranging from passive mechanical parts to mobile<p>robots. We present a taxonomy of the systems, and discuss their design and function. We then focus on a particular system, the swarm-bot. In swarm-bot, the components that assemble are self-propelled modules that are fully autonomous in power, perception, computation, and action. We examine the additional capabilities and functions self-assembly can offer an autonomous group of modules for the accomplishment of a concrete task: the transport of an object. The design of controllers is accomplished in simulation using<p>techniques from biologically-inspired computing. We show that self-assembly can offer adaptive value to groups that compete in an artificial evolution based on their fitness in task performance. Moreover, we investigate mechanisms that facilitate the design of self-assembling systems. The controllers are transferred to the physical swarm-bot system, and the capabilities of self-assembly and object transport are extensively evaluated in a range of different environments. Additionally, the controller for self-assembly is transferred and evaluated on a different robotic system, a super-mechano colony. Given the breadth and quality of the results obtained, we can say that the swarm-bot qualifies as the current state of the art in self-assembling robots. Our work supplies some initial evidence (in form of simulations and experiments with the swarm-bot) that self-assembly can offer robotic systems additional capabilities and functions useful for the accomplishment of concrete tasks.<p>Doctorat en Sciences de l'ingénieurinfo:eu-repo/semantics/nonPublishe
The Entries on Birds in Liu Xun’s Lingbiao lu yi
No full textThis article presents an annotated translation of the section on birds in Liu Xun’s Lingbiao lu yi (late 9th century). The author describes eleven birds of the Lingbiao region (roughly Guangdong, Guangxi, Hainan) in short notes that mix real and fictitious elements. This region, always considered dangerous and poorly civilized, was certainly not among the favorite locations of China’s civil servants. Although Liu Xun spent several years in the far South, very little is known about his life. But one can imagine that he felt unhappy in these lands, while at the same time admiring some of its unique features. That also applies to the entries on birds, especially on owls, in his text. The article is an attempt at “deciphering” these parts.Ce travail présente une traduction annotée de la section consacrée aux oiseaux dans l’ouvrage Lingbiao lu yi de Liu Xun (fin du IXe siècle). L’auteur choisit onze oiseaux de la région Lingbiao (correspondant à peu près au Guangdong, au Guangxi et à Hainan), et leur dédia des notes où les éléments réels et fantastiques paraissent entremêlés. Cette région, considérée comme peu civilisée et dangereuse, n’était pas un lieu où l’on souhaitait être envoyé comme fonctionnaire d’État. Liu Xun y servit pendant plusieurs années, mais on sait peu de choses de sa vie. On peut toutefois imaginer qu’il a été malheureux en ces terres lointaines, tout en étant admiratif de certaines de leurs particularités. Cela s’applique aussi aux descriptions des oiseaux dans son texte, notamment celles des hiboux. L’article est une tentative de « déchiffrer » ces passages.Bocci Chiara, Ptak Roderich. The Entries on Birds in Liu Xun’s Lingbiao lu yi. In: Bulletin de l'Ecole française d'Extrême-Orient. Tome 102, 2016. pp. 297-351
Bio-inspired self-organizing swarm robotics.
No full textSwarm robotics is the collaboration of a large number of robots to accomplish a set of specified tasks. It has great potential for the generation of self-organizing adaptive systems, where simple behaviours at agent level result in complex behaviours at swarm level. These systems promise to be robust, flexible, and scalable, and have many innovative applications in the future. Elimination of a central controller and instead relying on local awareness and distributed decision making are the main distinguishing characteristics of such, systems which make them different from classical engineering and necessitate a different design methodology. The challenges to design a control mechanism for self-organizing swarm robotic systems mainly come from the difficulty of mapping between the macroscopic behaviours of a swarm and the microscopic behaviours of its individual agents, and also decision making based on local awareness. Nature presents the best examples of self-organising collective systems. They can be divided into two categories, animal collective behaviours, and cellular organs. Although studying animal collective behaviours paves the way for understanding the principles of self-organizing collective systems, cellular organs show more complex behaviours and structures. The goal of this research is to adapt cellular morphogenesis mechanisms for collective behaviours in a swarm of minimalist robots. The trade of between the size of a swarm and the complexity of involved robots necessitates using simpler and cheaper robots. In addition, miniaturization of robots for future micro-robotic applications require to minimize the number of on-board devices in robots. In this thesis, we focus on developing minimalist algorithms inspired by biological morphogenesis for collective swarm behaviours, including collective flocking, target following, and target enclosure. The proposed algorithms are applicable to highly restricted robots without global positioning, directional sensing, motion feedback, and long-range communication devices. At first, I show how morphogens can retain the integrity and original shape of a swarm of robots without directional sensing, while the swarm moves and interacts with the environment. Then, a coordinated motion strategy is presented in order to preserve connectivity of a real swarm of minimalist robots following a target in their environment. Finally, a new approach is presented for target enclosure with a control over the shape of aggregation around the target. In this approach, a morphogen gradient produced by a target reacts with a second one diffusing through the edge of aggregation in order to spot weak points of the aggregation. The last two algorithms implemented in a real swarm of Kilobots
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