Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-02-13T15:08:25Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_FernandoRocha.pdf: 2031602 bytes, checksum: c22be1291e0dd7d53360e8930c5f5927 (MD5) / Made available in DSpace on 2017-02-13T15:08:25Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_FernandoRocha.pdf: 2031602 bytes, checksum: c22be1291e0dd7d53360e8930c5f5927 (MD5) Previous issue date: 2015-03-13 / CAPES / O desenvolvimento de soluções de Inteligência Artificial (IA) para sistemas computacionais é complexo dado a natureza dos problemas atacados, em particular quando envolvem problemas multiagentes e multitarefas (MAMT). Apesar de existirem vários métodos para o desenvolvimento de Sistema Multiagentes (SMA), são poucos os que dão alguma importância à compreensão do problema; e mesmo estes métodos não abordam os problemas MAMT com o devido detalhamento. Abordando a deficiência destas metodologias, estamos propondo o método Icelus que foca em guiar o analista em compreender e descrever corretamente o problema a ser solucionado. Icelus permitirá uma melhor abordagem na análise e compreensão de um problema MAMT, facilitando a distribuição do conhecimento para o restante do time de desenvolvimento, reduzindo o risco de erros de codificação ao longo do desenvolvimento do projeto. / The development of Artificial Intelligence (AI) to computational systems is a complex activity, given the nature of the problems attacked, in particular when they involve multi-agent problems and multitasking (MAMT). Although there are several methods for the development of Multi-agent System (MAS), there are just a few that give any importance to understanding the problem; and even these methods do not address the problems with all detailing that MAMT problems needs. Addressing the deficiency of these methods, we are proposing the Icelus method that focuses on leading the analyst to understand and describe correctly the problem to be solved. Icelus will enable a better approach in the analysis and understanding of a MAMT problem, facilitating the distribution of knowledge to the rest of the development team, reducing the risk of coding errors throughout the development of the project.

The study of Power TAC is a Multi-Agent competitive simulation test-bed, providing opportunity to simulate research and developments of electronic agents which can manage the tasks of the consumers and energy resources in a virtual energy infrastructure. According to the Power TAC scenario, Plug-in Electrical Vehicles are a special type of consumers that interact with this infrastructure and sometimes with the producers through aggregators. The aim of this study is modeling an intelligent Plug-in Electric vehicle agent for Power TAC that acts as an intermediary between Power TAC grid and vehicle owners. The proposed agent acts autonomously and is capable of making decisions about its energy needs by learning the driving behaviors and other preferences of these vehicle owners in a specified time interval. These agents will be able to make decisions about buying energy from the grid when the charging process is necessary or sell their energy back to the grid when the conditions of the electricity market are sufficiently attractive. The objective of this study is to model a Multi-Agent system for automating the process of charging the plug-in Vehicle Agents in Power TAC scenario by determining the necessary agents and the simulation environment where the agents constructed and simulated. Аs results of this study, different strategies are defined by considering the preferences of the vehicle owners and the conditions of the vehicle; thereby the agents autonomously bid behalf of their user in order to automate the process of charging.

Modern operating systems should be extensible and flexible. This means that the operating system should be able to accept new behaviour and change existing behaviour without too much trouble and that it should ideally also be able to do this without any, or very little, downtime. Furthermore, during the past years the importance of the network has increased drastically, creating a demand for operating systems to function in a distributed environment. To achieve this flexibility and distribut-edness, I have designed and evaluated ABOS, an Agent-Based Operating System. ABOS uses agents to solve all the tasks of the operating system kernel, thus moving away from traditional monolithic kernel structures. Early results show that I have gained in flexibility and modularity, creating a fault-tolerant distributed operating system that can adapt and be adapted to almost any situa-tion with negligible decrease in performance. Within ABOS some tasks has been designed further, and there exists a demonstration of how the agent-based filesystem might work.

Design patterns document a field's systematic knowledge derived from experiences. Despite the vast body of work in the field of multi-agent systems (MAS), design patterns for MAS are not popular among software practitioners. As MAS have features that are widely considered as key to engineering complex distributed applications, for example in manufacturing, robotics, ecommerce, traffic control and coordination, science simulations, it is important to provide a clear overview of existing patterns to make this knowledge accessible. To that end, a systematic literature review was performed covering the main publication venues of the field since 1998, resulting in 206 patterns. The study shows that (1) there is a lack of a standard template for documenting design patterns for MAS, which hampers the use of patterns by practitioners, (2) associations between patterns are poorly described, which results in a lack of overview of the pattern space, (3) patterns for MAS have been used for a variety of application domains, which underpins their high potential for practitioners, and (4) classifications of design patterns for MAS are bounded to specific pattern catalogs, a more holistic view on the pattern space is missing. From the study, a number of guidelines is outlined that are important for future work on design patterns for MAS and their adoption in practice.

For underwater robotics there exists severe constraints regarding wireless bandwidth in the kilobits range. This makes a centralised approach to high-level mission management possibly less than ideal due to inherent delays and possible temporary incompleteness in data during decision making. This thesis aims to propose, implement (in ROS) and test a distributed approach. An auction based method for task assignment was being used, as well as a Pagerank based approach that models a trust based hierarchy between autonomous agents inferred from information exchange, in order to enforce decision conformity. Simulations where carried out using UWsim and a custom made bandwidth limiter for ROS. It was concluded that the Pagerank based algorithm managed to uphold conformity and solve conflicts during network slowdown but did not always lead to the correct decisions being enforced.

This dissertation aims at solving the consensus control problem of multi-agent systems with Lipschitz nonlinearity. This depends on the design of the controller that enables each agent or subsystem in multi-agent systems with Lipschitz nonlinearity to reach consensus; using the understanding of the agents' connection network from the knowledge of graph theory as well as the control system design strategy. The objective is achieved by designing a type of distributed control, namely the consensus control, which manipulates the relative information of each agent in a multi-agent systems in order to arrive at a single solution. In addition, containment control is also developed to solve containment problem. It is an extension of consensus control via leader-follower configuration, aimed at having each agent contained by multiple leaders in a multi-agent systems with Lipschitz nonlinearity. Four types of controllers are proposed - state-feedback consensus controller, observer-based consensus controller, state-feedback containment controller and observer-based containment controller; each provides the stability conditions based on Lyapunov stability analysis in time domain which enabled each agent or subsystem to reach consensus. The observer-based controllers are designed based on the consensus observer that is related to Luenberger observer. Linear Matrix Inequality (LMI) and Algebraic Riccati Equation (ARE) are utilized to obtain the solutions for the stability conditions. The simulation results of the proposed controllers and observers have been carried out to prove their theoretical validity. Several practical examples of flexible robot arm simulations are included to further validate the theoretical aspects of the thesis.

Multi-agent multi-team systems are commonly seen in environments where hierarchical layers of goals are at play. For example, theater-wide combat scenarios where multiple levels of command and control are required for proper execution of goals from the general to the foot soldier. Similar structures can be seen in game environments, where agents work together as teams to compete with other teams. The different agents within the same team must, while maintaining their own ‘personality’, work together and coordinate with each other to achieve a common team goal. This research develops strategy-based multi-agent multi-team systems, where strategy is framed as an instrument at the team level to coordinate the multiple agents of a team in a cohesive way. A formal specification of strategy and strategy-based multi-agent multi-team systems is provided. A framework is developed called SiMAMT (strategy- based multi-agent multi-team systems). The different components of the framework, including strategy simulation, strategy inference, strategy evaluation, and strategy selection are described. A graph-matching approximation algorithm is also developed to support effective and efficient strategy inference. Examples and experimental results are given throughout to illustrate the proposed framework, including each of its composite elements, and its overall efficacy. This research make several contributions to the field of multi-agent multi-team systems: a specification for strategy and strategy-based systems, and a framework for implementing them in real-world, interactive-time scenarios; a robust simulation space for such complex and intricate interaction; an approximation algorithm that allows for strategy inference within these systems in interactive-time; experimental results that verify the various sub-elements along with a full-scale integration experiment showing the efficacy of the proposed framework.

Cooperative control of multi-agent systems (MASs) has been intensively investigated in the past decade. The task is always complicated for an individual agent, but can be achieved by collectively operating a group of agents in a reliable, economic and efficient way. Although a lot of efforts are being spent on improving MAS performances, much progress has yet to be developed on different aspects. This thesis aims to solve problems in the consensus control of multiple quadrotors and/or mobile robots considering irregular sampling controls, heterogeneous agent dynamics and the presence of model uncertainties and disturbances. The thesis proceeds with Chapter 1 by providing the literature review of the state-of-the-art development in the consensus control of MASs. Chapter 2 introduces experimental setups of the laboratory involving two-wheeled mobile robots (2WMRs), quadrotors, positioning systems and inter-vehicle communications. All of the developed theoretical results in Chapters 3-6 are experimentally verified on the platform. Then it is followed by two main parts: Irregular sampling consensus control methods (Chapter 3 and 4) and cooperative control of heterogeneous MASs (Chapter 5 and 6). Chapter 3 focuses on the non-uniform sampling consensus control for a group of 2WMRs, and Chapter 4 studies the event-based rendezvous control for a group of asynchronous robots with time-varying communication delays. Chapter 5 concentrates on cooperative control methods for a heterogeneous MAS consisting of quadrotors and 2WMRs. Chapter 6 focuses on the design of a quadrotor flight controller which is robust to various adverse factors such as model uncertainties and external disturbances. The developed controller is further applied to the consensus control of the heterogeneous MAS. Specifically, Chapter 3 studies synchronized and non-periodical sampling consensus control methods for a group of 2WMRs. The directed and switching communication topologies among the network are considered in the controller design. The 2WMR is an underactuated system, which implies that it can not generate independent x and y accelerations in the two-dimensional plane. The rendezvous control methods are proposed for 2WMRs. The algebraic graph theory and stochastic matrix analysis are employed to conduct the convergence analysis. Although the samplings in the work of Chapter 3 are aperiodic, one feature is that local clocks of agents are required to be synchronized. Challenges arise in the practical control of distributed MASs, especially in the scenario that the global clock is lacking. Moreover, frequent samplings can result in redundant information transmissions when the communication bandwidth is limited. To address these problems, Chapter 4 investigates an event-based rendezvous control method for a group of asynchronous MAS with time-varying communication delays. Integral-type triggering conditions for each robot are adopted to be checked periodically. If the triggering condition is satisfied at one checking instant, the agent samples and broadcasts the state to the neighbors with a bounded communication delay. Then an algorithm is provided for driving 2WMRs to asymptotically reach rendezvous. The convergence analysis is conducted through Lyapunov approaches. Most of the theoretical works on cooperative control are focused on controlling agents with identical dynamics. However, in certain realistic scenarios, some complex missions require the cooperation of different types of agent dynamics such as surveillance, search and rescue, etc. Tasks can be carried out with higher efficiency by employing both the autonomous ground vehicles and unmanned aerial vehicles. To achieve better performance for MASs, in Chapter 5, distributed cooperative control methods for a heterogeneous MAS consisting of quadrotors and 2WMRs are developed. Consensus conditions are provided, and the theoretical results are experimentally verified. Many existing quadrotor control methods need exact model parameters of the quadrotor. In reality, when a quadrotor is conducting some tasks with extra payloads or with unexpected damages to the model structure, errors in parameters could result in the failure of the flight. External disturbances also inevitably affect the flight performance. To move a step further towards practical applications, in Chapter 6, a robust quadrotor flight controller using Integral Sliding Mode Control (ISMC) technique is investigated. In experiments, an extra payload with the position and mass unknown, is attached to destroy the accuracy of the model and to add disturbances. The designed controller significantly rejects negative effects caused by the payload during the flight. This controller is also successfully applied to an MAS consisting of a quadrotor and 2WMRs. / Graduate

Orientador: Edmundo Roberto Mauro Madeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-22T03:57:24Z (GMT). No. of bitstreams: 1 SoaresJunior_MiltonAparecido_M.pdf: 2099044 bytes, checksum: 9429a525b941834e987d70cb3b26c2fc (MD5) Previous issue date: 2013 / Resumo: Apesar do seu sucesso, a arquitetura atual da Internet _e uma fonte de vários problemas para as aplicações atuais e as demandas futuras. A virtualização da infraestrutura da rede é proposta como alternativa para solucionar esses problemas sem a necessidade de alterar o núcleo da Internet, pois ela habilita o pluralismo de arquiteturas de rede. Neste trabalho, foi desenvolvida uma arquitetura de gerência autonômica de redes virtuais baseada em sistemas multiagentes. Um protótipo que realiza a função de autocura de redes virtuais foi implementado a partir dessa arquitetura. Novos algoritmos e mecanismos foram desenvolvidos para melhorar a eficiência do protótipo. Foi realizado, também, um estudo de caso sobre a gerência de redes virtuais que leva em consideração os requisitos das aplicações que estão sendo executadas em uma nuvem. Uma plataforma de experimentação baseada em máquinas virtuais e no OpenFlow foi criada para a execução dos experimentos. Tanto o protótipo quanto a plataforma de experimentação integram ferramentas atuais criando uma única solução para a gerência de redes virtuais. Os resultados apresentados contribuem para aproximar a virtualização de redes e a gerência autonômica da realidade / Abstract: Despite its success, the current architecture of the Internet is a source of many problems for current applications and future demands. The virtualization of network infrastructure is proposed as an alternative to solve these problems without the need to change the core of the Internet, as it enables the network architecture pluralism. We have developed architecture for autonomic management of virtual networks based on multi-agent systems. Based on this architecture, we implemented a prototype that performs the function of self-healing virtual networks. New algorithms and mechanisms have been developed to improve the efficiency of the prototype. A case study on the management of virtual networks that takes into consideration the requirements of the applications that are running on a cloud is also presented. For the execution of the experiments was created an experimentation platform based on virtual machines and on OpenFlow. The prototype and the platform integrate current tools creating a single solution for management of virtual networks. The results contributed to bring network virtualization and autonomic management closer to reality / Mestrado / Ciência da Computação / Mestre em Ciência da Computação

Hoy en día los sistemas informáticos complejos se pueden ven en términos de los servicios que ofrecen y las entidades que interactúan para proporcionar o consumir dichos servicios. Los sistemas multi-agente abiertos, donde los agentes pueden entrar o salir del sistema, interactuar y formar grupos (coaliciones de agentes u organizaciones) de forma dinámica para resolver problemas, han sido propuestos como una tecnología adecuada para implementar este nuevo paradigma informático. Sin embargo, el amplio dinamismo de estos sistemas requiere que los agentes tengan una forma de armonizar los conflictos que surgen cuando tienen que colaborar y coordinar sus actividades. En estas situaciones, los agentes necesitan un mecanismo para argumentar de forma eficiente (persuadir a otros agentes para que acepten sus puntos de vista, negociar los términos de un contrato, etc.) y poder llegar a acuerdos. La argumentación es un medio natural y efectivo para abordar los conflictos y contradicciones del conocimiento. Participando en diálogos argumentativos, los agentes pueden llegar a acuerdos con otros agentes. En un sistema multi-agente abierto, los agentes pueden formar sociedades que los vinculan a través de relaciones de dependencia. Estas relaciones pueden surgir de sus interacciones o estar predefinidas por el sistema. Además, los agentes pueden tener un conjunto de valores individuales o sociales, heredados de los grupos a los que pertenecen, que quieren promocionar. Las dependencias entre los agentes y los grupos a los que pertenecen y los valores individuales y sociales definen el contexto social del agente. Este contexto tiene una influencia decisiva en la forma en que un agente puede argumentar y llegar a acuerdos con otros agentes. Por tanto, el contexto social de los agentes debería tener una influencia decisiva en la representación computacional de sus argumentos y en el proceso de gestión de argumentos. / Heras Barberá, SM. (2011). Case-Based Argumentation in Agent Societies [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/12497 / Palancia