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Ghellere, Reginaldo. "REDES DE COOPERAÇÃO DA AGRICULTURA FAMILIAR DO SUL DE SANTA CATARINA." Universidade Federal de Santa Maria, 2014. http://repositorio.ufsm.br/handle/1/8908.
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Empresa Brasileira de Pesquisa Agropecuária<br>This research discusses the role of family agriculture cooperative networks in country life social and economic aspects in southern Santa Catarina. Since colonization period, mainly Italian and German, the region has a history of several agricultural cooperatives formed by agricultural product, some of which having already more than 45 years of operation. From the year 2004, seeking to meet the needs of marketing, appear new agricultural cooperatives in the decentralized model. Thus, the study aims to analyze the importance of agricultural cooperatives by product and decentralized to the social reproduction of family farmers associated with them. To meet this purpose was done a research with twenty associated from four agricultural cooperatives, two by product and two decentralized. The study shows how these cooperatives contribute positively with associated families by creating favorable marketing conditions to local farmers and also providing technical improvement. However, even with the recognition of the benefits of the cooperative, it was found that some associated have not sold their entire production through its cooperative thereby resulting in economic and social losses for the entire system.<br>Esta investigação versa sobre o papel das redes de cooperação da agricultura familiar na reprodução social das famílias de agricultores familiares. As redes de cooperação estudadas são delimitadas por cooperativas agropecuárias por produto e descentralizadas, localizadas no Sul de Santa Catarina. Desde sua colonização, principalmente italiana e alemã, a região possui um histórico de diversas cooperativas agropecuárias constituídas por produto agrícola, sendo que algumas delas possuem mais de 45 anos de funcionamento. A partir do ano de 2004, procurando atender as necessidades de comercialização de produtos processados pelos próprios agricultores, nos mercados local e institucional, são constituídas novas cooperativas agropecuárias no formato descentralizadas. Assim, o estudo teve como objetivo principal, analisar a importância das cooperativas agropecuárias por produto e descentralizadas para a reprodução social dos agricultores familiares associados às mesmas. Para tanto, foi feita uma pesquisa com vinte associados de quatro cooperativas agropecuárias, sendo duas por produto e duas descentralizadas. O estudo demonstrou que as cooperativas contribuem positivamente com as famílias associadas. Enquanto as cooperativas por produto conseguem ditar condições favoráveis de comercialização do mercado local aos agricultores sócios e também a não-sócios, bem como prestar apoio técnico e oferta de insumos, as cooperativas descentralizadas, por sua vez, viabilizam o acesso a diversos canais de comercialização aos seus associados a partir da formalização dos empreendimentos dos associados. Porém, mesmo com o reconhecimento dos benefícios da cooperativa, constatou-se que alguns cooperados não tem comercializado a totalidade de sua produção por meio das suas cooperativas. Isto resulta em perdas econômicas e sociais para as cooperativas e, respectivamente, para o conjunto dos associados.
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Zhang, Lu. "Decentralized cooperative communication for wireless relaying networks." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 202 p, 2009. http://proquest.umi.com/pqdweb?did=1885757461&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Omidshafiei, Shayegan. "Decentralized teaching and learning in cooperative multiagent systems." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120422.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 123-140).<br>Cooperative multiagent decision making is a ubiquitous problem with many real-world applications, including organization of driverless car fleets [1, 2], target surveillance [3], and warehouse automation [4-6]. The unifying challenge in these real-world settings is the presence of domain stochasticity (due to noisy sensors and actuators) and partial observability (due to local perspectives of agents), which can obfuscate the underlying state. In many practical applications, it is desirable for teams of agents to be capable of executing well-coordinated policies despite these uncertainty challenges. The core assumption of standard multiagent planning approaches is knowledge of an accurate, high-fidelity environment model. In practice, models may be unavailable or inaccurate. In the former case, models necessary for planning-based approaches must be generated or learned (which may be difficult and/or expensive). In the latter, execution of policies optimized for incorrect models may have dire economic and/or social consequences for systems deployed in the real world. While many works have introduced learning (rather than planning) approaches for multiagent systems, few address the partially observable setting, and even fewer do so in a scalable manner deployable to real-world settings, such as multi-robot systems that face collections of tasks [7]. The primary objective of this thesis is to develop technologies for scalable learning-based coordination in multiagent settings. Specifically, this thesis introduces methods for hierarchical learning of models and policies that enable multiagent coordination with more realistic sensors, execution in settings where underlying environment contexts may be non-unique or non-stationary, and acceleration of cooperative learning using inter-agent advice exchange. The algorithms developed are demonstrated in a variety of hardware and simulation settings, including those with complex sensory inputs and realistic dynamics and/or learning objectives, extending beyond the usual task-specific performance objectives to meta-learning (learning to learn) and multitask learning objectives.<br>by Shayegan Omidshafiei.<br>Ph. D.
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Summerfield, Nichalin Suakkaphong. "Games of Decentralized Inventory Management." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/194894.
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Any decentralized retail or wholesale system of competing entities requires a benefit sharing arrangement when competing entities collaborate after their demands are realized. For instance, consider a distribution system similar to the observed behavior of independent car dealerships. If a dealership does not have in stock the car requested by a customer, it might consider acquiring it from a competing dealer. Such behavior raises questions about competitive procurement strategies that achieve system optimal outcomes. This dissertation consists of three main bodies of work contained respectively in chapters 2, 3, and 4. In the first work -- chapter 2, we examine a decentralized system that adopts an ex-post agreed transfer payment approach proposed by Anupindi et al. (Manuf. Serv. Oper.Manag. 4(3):349-368, 2001). In particular, we state a set of conditions on cost parameters and distributions that guarantee uniqueness of pure strategy Nash equilibrium. In the second work -- chapter 3, we introduce a multilevel graph framework that links decentralized inventory distribution models as a network of stochastic programming with recourse problems. This framework depicts independent retailers who maximize their individual expected profits, with each retailer independently procuring inventory in the ex-ante stage in response to forecasted demand and anticipated cooperative recourse action of all retailers in the system. The graph framework clarifies the modeling connection between problems in a taxonomy of decentralized inventory distribution models. This unifying perspective links the past work and shades light on future research directions. In the last work -- chapter 4, we examine and recast the biform games modeling framework as two-stage stochastic programming with recourse. Biform games modeling framework addresses two-stage games with competitive first stage and cooperative second stage without ex-ante agreement on profit sharing scheme. The two-stage stochastic programming view of biform games is demonstrated on examples from all the known examples regarding operational decision problems of competing firms from the literature. It allows an “old” mathematical methodology to showcase its versatility in modeling combined competitive and cooperative game options. In short, this dissertation provides important insights, clarifications, and strategic limitations regarding collaborations in decentralized distribution system.
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Farahmand, Ashil Sayyed. "Cooperative Decentralized Intersection Collision Avoidance Using Extended Kalman Filtering." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/36276.
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Automobile accidents are one of the leading causes of death and claim more than 40,000 lives annually in the US alone. A substantial portion of these accidents occur at road intersections. Stop signs and traffic signals are some of the intersection control devices used to increase safety and prevent collisions. However, these devices themselves can contribute to collisions, are costly, inefficient, and are prone to failure. This thesis proposes an adaptive, decentralized, cooperative collision avoidance (CCA) system that optimizes each vehicle's controls subject to the constraint that no collisions occur. Three major contributions to the field of collision avoidance have resulted from this research. First, a nonlinear 5-state variable vehicle model is expanded from an earlier model developed in [1]. The model accounts for internal engine characteristics and more realistically approximates vehicle behavior in comparison to idealized, linear models. Second, a set of constrained, coupled Extended Kalman Filters (EKF) are used to predict the trajectory of the vehicles approaching an intersection in real-time. The coupled filters support decentralized operation and ensure that the optimization algorithm bases its decisions on good, reliable estimates. Third, a vehicular network based on the new WAVE standard is presented that provides cooperative capabilities by enabling intervehicle communication. The system is simulated against today's common intersection control devices and is shown to be superior in minimizing average vehicle delay.<br>Master of Science
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Bazco, Nogueras Antonio. "Fundamental Limits and Algorithms in Decentralized and Cooperative Wireless Networks." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS172.
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La coopération en réseau est connue pour apporter des gains multiplicatifs sous certaines hypothèses idéales. Cependant, les réseaux sans-fil actuels font face à de nombreuses contraintes, telles que des contraintes de délai serrées ou des liaisons de retour à débit limité. L'impact sur la performance de la transgression des hypothèses idéales a suscité un grand intérêt dans le milieu de la recherche. Néanmoins, l'accent a été mis sur des situations dans lesquelles l'information imparfaite est partagée par tous les nœuds, ce qui n'est pas réalisable dans de nombreux scénarios. Cette thèse vise à mettre en lumière la performance des environnements coopératifs dans lesquels l'information disponible à chaque nœud peut être différente. Nous nous concentrons sur le réseau distribué MIMO. Ce réglage se caractérise par avoir un partage parfait des données d'information et un partage imparfait des informations du canal. Nous caractérisons la métrique des degrés de liberté, qui est une approximation de la capacité à un SNR élevé. La contribution est double, puisque nous fournissons à la fois des schémas réalisables qui surpassent considérablement les solutions de la littérature et des limites supérieures qui illustrent jusqu'à quelle échelle l'environnement distribué est affecté par rapport au partage parfait. Une deuxième perspective consiste à limiter la transmission au paradigme du zéro-forçage et à analyser le taux à un SNR élevé pour comprendre si les pertes de performance dues à la décentralisation peuvent être calculées avec précision. Nous proposons un nouveau système de zéro-forçage adapté à la configuration décentralisée qui atteint asymptotiquement le taux centralisé<br>Network cooperation is known to bring multiplicative gains under certain ideal assumptions. However, current wireless settings cope with many challenging constraints, as tight delay constraints, fast-changing channels, or rate-limited backhaul links. The topic of analyzing how the non-fulfillment of the ideal hypotheses impacts the performance has generated great interest in the research community. Nevertheless, the main focus has been on settings in which the imperfect information is shared by all the nodes, which is not feasible in many scenarios. This thesis aims for shedding light on the performance of cooperative settings in which the information available at each node may be different. We focus on the distributed Network MIMO. This setting is characterized by two main aspects: The perfect sharing of the user's information data and the imperfect sharing of the channel information. We start by characterizing the Degrees-of-Freedom metric of the setting, which is an approximation of the capacity at high SNR. The contribution is twofold, as we provide both achievable schemes that considerably outperform the solutions in the literature and upper-bounds that illustrate up to which scale the distributed setting is harmed with respect to the perfect-sharing setting. The second perspective consists in restricting the transmission to the conventional paradigm of Zero-Forcing and analyzing the achievable rate at high SNR to understand whether the performance losses from decentralized information can be accurately calculated. We propose a novel zero-forcing scheme tailored to the decentralized configuration that asymptotically attains the centralized rate
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Zimba, Anthony Andile. "Decentralised cooperative governance in the South African metropolitan municipalities." Thesis, University of Fort Hare, 2012. http://hdl.handle.net/10353/536.
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The study emanates from the constitutional imperatives with regard to the role of local government in community development. The notion of cooperative governance is envisaged in the South African Constitution which stipulates that all spheres of government must adhere to the principles of cooperative government and must conduct their activities within the parameters prescribed by the Constitution. The purpose is to support and strengthen the capacity of the local governments to manage their own affairs and to perform their functions. The basic values and principles governing public administration entail that: it must be broadly representative of the people of South Africa in order to redress the imbalances. The existing gaps in the legislation on decision making power at the local level of the municipality, be it in a ward committee or sub council, have not been adequately addressed in the post 1994 democratic dispensation. It is in this context that this study seeks to address these gaps and obstacles, and contribute to the design and development of a decentralized cooperative governance model, specifically to the six metropolitan municipalities and also provide a basis for further research. The findings of the research could be adapted as a national policy in the empowering of municipalities through the dispersal of democratic power which is an essential ingredient of inclusive governance. Based on a case study of six metropolitan municipalities, the research is intended to contribute to the development of empirically grounded; praxis and practical guideline in decentralized cooperative governance which can be adopted and institutionalized in public administration. It is believed that a study of decentralized cooperative governance adds value in that it seeks to link decentralized power and local development. Rather than civil society organisations being seen as adversarial, a creative partnership with the state in local development is crucial. This political assimilation is critical in the construction of democracy through fusing the substantive values of a political culture with the procedural requisites of democratic accountability. This serves to fragment and disperse political power and maintain a system of checks and balances with regard to the exercise of governmental power. The capacity for innovation, flexibility and change can be enhanced at the local level, and it is a cliché that local decision making is viewed as more democratic in contrast to central, top-down decision-making processes. A syncretistic model for local government based on the political adaptation of political and inclusive decentralisation is outlined.
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Cao, Yongcan. "Decentralized Coordination of Multiple Autonomous Vehicles." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/652.
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This dissertation focuses on the study of decentralized coordination algorithms of multiple autonomous vehicles. Here, the term decentralized coordination is used to refer to the behavior that a group of vehicles reaches the desired group behavior via local interaction. Research is conducted towards designing and analyzing distributed coordination algorithms to achieve desired group behavior in the presence of none, one, and multiple group reference states. Decentralized coordination in the absence of any group reference state is a very active research topic in the systems and controls society. We first focus on studying decentralized coordination problems for both single-integrator kinematics and double-integrator dynamics in a sampled-data setting because real systems are more appropriate to be modeled in a sampled-data setting rather than a continuous setting. Two sampled-data consensus algorithms are proposed and the conditions to guarantee consensus are presented for both fixed and switching network topologies. Because a number of coordination algorithms can be employed to guarantee coordination, it is important to study the optimal coordination problems. We further study the optimal consensus problems in both continuous-time and discrete-time settings via an linear-quadratic regulator (LQR)-based approach. Noting that fractional-order dynamics can better represent the dynamics of certain systems, especially when the systems evolve under complicated environment, the existing integer-order coordination algorithms are extended to the fractional-order case. Decentralized coordination in the presence of one group reference state is also called coordinated tracking, including both consensus tracking and swarm tracking. Consensus tracking refers to the behavior that the followers track the group reference state. Swarm tracking refers to the behavior that the followers move cohesively with the external leader while avoiding inter-vehicle collisions. In this part, consensus tracking is studied in both discrete-time setting and continuous-time settings while swarm tracking is studied in a continuous-time setting. Decentralized coordination in the presence of multiple group reference states is also called containment control, where the followers will converge to the convex hull, i.e., the minimal geometric space, formed by the group references states via local interaction. In this part, the containment control problem is studied for both single-integrator kinematics and double-integrator dynamics. In addition, experimental results are provided to validate some theoretical results.
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Negri, Juliana Andressa. "Uma abordagem do preço de transferência em cooperativa agroindustrial do norte do Paraná." Pontifícia Universidade Católica de São Paulo, 2008. https://tede2.pucsp.br/handle/handle/1690.
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Previous issue date: 2008-05-12<br>The transfer price is a managerial tool with the purpose of coordinating the decisions of a company in the reach of their goals, through a fastened value. It includes the operations of sales or the products transfers, services, being present in decentralized units, in other words, companies that chose for their organizational fragmentation, dividing their fastened structure in areas of businesses.
In this context, the main objective of this work was to verify the importance of the transfer pricing used in the decentralized units of a agroindustrial cooperative, studying their procedures, as well as the treatment and identification of the methodology adopted in that inside sale process in the reception divisions and refine of the soy.
This way, through a case study, it was tried to identify the participation of the decentralized units in the result of the agroindustrial cooperative of the north of Paraná, and the inside transfer pricing adopted by this organization.
Therefore, it is concluded that the performance of each one of the units affects in a direct way the final result of the company, although each responsibility center adopts a pricing mechanism in keeping with their activities. The importance of the administration of the transfer price optimizes this process in a positive way; however it is compacted or very close to the costing ways, harming, consequently, its work as a performance measurer<br>O preço de transferência é uma ferramenta gerencial com a finalidade de coordenar as decisões de uma empresa no alcance de suas metas, através de um valor fixado. Abrange as operações de vendas ou as transferências de produtos, serviços, estando presente em unidades descentralizadas, ou seja, companhias que optaram pela sua fragmentação organizacional, dividindo suas estrutura fixa em áreas de negócios.
Neste contexto, o objetivo principal desse trabalho foi verificar a importância do apreçamento de transferência utilizado nas unidades descentralizadas de uma cooperativa agroindustrial, estudando seus procedimentos, bem como o tratamento e identificação da metodologia adotada nesse processo de venda interna nas divisões de recebimento e refino da soja.
Assim, através de um estudo de caso, procurou-se identificar a participação das unidades descentralizadas no resultado da cooperativa agroindustrial do norte do Paraná, e o apreçamento de transferência interno adotado por essa organização.
Portanto, conclui-se que desempenho de cada uma das unidades afeta de forma direta o resultado final da empresa, embora cada centro de responsabilidade adote um mecanismo de apreçamento condizente com suas atividades. A importância da gestão do preço de transferência otimiza esse processo de forma positiva, contudo está compactado ou muito próximo as formas de custeio, prejudicando consequentemente seu trabalho como mensurador da performance
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Wei, Qiang. "Studies on decentralized cooperative learning systems for logistics planning and collaborative control." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/145353.
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Gui, Luyi. "Managing and optimizing decentralized networks with resource sharing." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47707.
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Resource sharing is a common collaborative strategy used in practice. It has the potential to create synergistic value and leads to higher system efficiency. However, realizing this synergistic value can be challenging given the prevalence of decentralization in practice, where individual operators manage resources based on their own benefits. Hence, optimizing a decentralized system requires understanding not only the optimal operational strategy in terms of the overall system efficiency, but also the implementation of the strategy through proper management of individual incentives. However, traditional network optimization approaches typically assume a centralized perspective. The classic game theory framework, on the other hand, addresses incentive issues of decentralized decision makers, but mainly takes a high-level, economic perspective that does not fully capture the operational complexity involved in optimizing systems with resource sharing.
The purpose of this thesis is to bridge this gap between practice and theory by studying the design of tools to manage and optimize the operations in decentralized systems with resource sharing using approaches that combine optimization and game theory. In particular, we focus on decentralized network systems and analyze two research streams in two application domains: (i) implementation of environmental legislation, and (ii) managing collaborative transportation systems. These applications are characterized by their decentralized multi-stakeholder nature where the conflicts and tension between the heterogeneous individual perspectives make system management very challenging. The main methodology used in this thesis is to adopt game theory models where individual decisions are endogenized as the solutions to network optimization problems that reflect their incentives. Such an approach allows us to capture the connection between the operational features of the system (e.g., capacity configuration, network structure, synergy level from resource sharing) and the individual incentives thus the effectiveness of the management tools, which is a main research contribution of this thesis.
In the first research stream, we consider designing effective, efficient and practical implementation of electronic waste take-back legislation based on the widely-adopted Extended Producer Responsibility (EPR) concept that mandates the financial responsibility of post-use treatment of their products. Typical implementations of EPR are collective, and allocate the resulting operating cost to involved producers. In this thesis, we demonstrate the complexity of collective EPR implementation due to the tension among different stakeholder perspectives, based on a case analysis of the Washington implementation. We then perform analytical studies of the two prominent challenges identified in current implementations: (i) developing cost allocation mechanisms that induce the voluntary participation of all producers in a collective system, thus promoting implementation efficiency; and (ii) designing collective EPR so as to encourage environmentally-friendly product design, thus promoting implementation effectiveness. Specifically, we prescribe new cost allocation methods to address the first challenge, and demonstrate the practicality and economic impact of the results using implementation data from the state of Washington. We then analyze the tensions between design incentives, efficiency and the effectiveness of the cost allocation to induce voluntary participation under collective EPR implementation. We show there exists a tradeoff among the three dimensions, driven by the network effects inherent in a collective system. The main contribution of this research stream is to demonstrate how the implementation outcomes of an environmental policy is influenced by the way that the policy ``filters' through operational-level factors, and to propose novel and implementation mechanisms to achieve efficient and effective EPR implementation. Hence, our study has the potential to provide guidance for practice and influence policy-making.
In the second research stream, motivated by the practice of transportation alliances, we focus on a decentralized network setting where the individual entities make independent decisions regarding the routing of their own demand and the management of their own capacity, driven by their own benefits. We study the use of market-based exchange mechanisms to motivate and regulate capacity sharing so as to achieve the optimal overall routing efficiency in a general multicommodity network. We focus on the design of capacity pricing strategies in the presence of several practical operational complexities, including multiple ownership of the same capacity, uncertainty in network specifications, and information asymmetry between the central coordinator and individual operators. Our study in this research stream produces two sets of results. First, we demonstrate the impact of the underlying network structure on the effectiveness of using market-based exchange mechanisms to coordinate resource sharing and to allocate the resulting synergistic benefit, and characterize the network properties that matter. Second, we propose efficient and effective pricing policies and other mechanism design strategies to address different operational complexities. Specifically, we develop duality-based pricing algorithms, and evaluate different pricing strategies such as commodity-based price discrimination, which is shown to have an advantage in coordinating networks under uncertainty.
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Sivakumaran, Arun. "Malicious user attacks in decentralised cognitive radio networks." Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/79657.
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Cognitive radio networks (CRNs) have emerged as a solution for the looming spectrum crunch caused
by the rapid adoption of wireless devices over the previous decade. This technology enables efficient
spectrum utility by dynamically reusing existing spectral bands. A CRN achieves this by requiring its
users – called secondary users (SUs) – to measure and opportunistically utilise the band of a legacy
broadcaster – called a primary user (PU) – in a process called spectrum sensing. Sensing requires the
distribution and fusion of measurements from all SUs, which is facilitated by a variety of architectures
and topologies.
CRNs possessing a central computation node are called centralised networks, while CRNs composed of
multiple computation nodes are called decentralised networks. While simpler to implement, centralised
networks are reliant on the central node – the entire network fails if this node is compromised. In
contrast, decentralised networks require more sophisticated protocols to implement, while offering
greater robustness to node failure. Relay-based networks, a subset of decentralised networks, distribute
the computation over a number of specialised relay nodes – little research exists on spectrum sensing
using these networks. CRNs are vulnerable to unique physical layer attacks targeted at their spectrum sensing functionality.
One such attack is the Byzantine attack; these attacks occur when malicious SUs (MUs) alter their
sensing reports to achieve some goal (e.g. exploitation of the CRN’s resources, reduction of the CRN’s
sensing performance, etc.). Mitigation strategies for Byzantine attacks vary based on the CRN’s
network architecture, requiring defence algorithms to be explored for all architectures. Because of the
sparse literature regarding relay-based networks, a novel algorithm – suitable for relay-based networks
– is proposed in this work. The proposed algorithm performs joint MU detection and secure sensing by
large-scale probabilistic inference of a statistical model.
The proposed algorithm’s development is separated into the following two parts.
• The first part involves the construction of a probabilistic graphical model representing the
likelihood of all possible outcomes in the sensing process of a relay-based network. This is
done by discovering the conditional dependencies present between the variables of the model.
Various candidate graphical models are explored, and the mathematical description of the chosen
graphical model is determined.
• The second part involves the extraction of information from the graphical model to provide
utility for sensing. Marginal inference is used to enable this information extraction. Belief
propagation is used to infer the developed graphical model efficiently. Sensing is performed by
exchanging the intermediate belief propagation computations between the relays of the CRN.
Through a performance evaluation, the proposed algorithm was found to be resistant to probabilistic
MU attacks of all frequencies and proportions. The sensing performance was highly sensitive to
the placement of the relays and honest SUs, with the performance improving when the number of
relays was increased. The transient behaviour of the proposed algorithm was evaluated in terms of its
dynamics and computational complexity, with the algorithm’s results deemed satisfactory in this regard.
Finally, an analysis of the effectiveness of the graphical model’s components was conducted, with a
few model components accounting for most of the performance, implying that further simplifications
to the proposed algorithm are possible.<br>Dissertation (MEng)--University of Pretoria, 2020.<br>Electrical, Electronic and Computer Engineering<br>MEng<br>Unrestricted
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Filotheou, Alexandros. "Robust Decentralized Control of Cooperative Multi-robot Systems : An inter-constraint Receding Horizon approach." Thesis, KTH, Reglerteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207943.
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In this work, a robust decentralized model predictive control regime for a team of cooperating robot systems is designed. Their assumed dynamics are in continuous time and non-linear. The problem involves agents whose dynamics are independent of one-another, and its solution couples their constraints as a means of capturing the cooperative behaviour required. Analytical proofs are given to show that, under the proposed control regime: (a) Subject to initial feasibility, the optimization solved at each step by each agent will always be feasible, irrespective of whether or not disturbances affect the agents. In the former case, recursive feasibility is established through successive restriction of each agent's constraints during the periodic solution to its respective optimization problem. (b) Each (sub)system can be stabilized to a desired configuration, either asymptotically when uncertainty is absent, or within a neighbourhood of it, when uncertainty is present, thus attenuating the affecting disturbance. In this context, disturbances are assumed to be additive and bounded. Simulations verify the efficacy of the proposed method over a range of different operating environments.<br>I detta arbete, en robust decentraliserad modell prediktiv kontroll regime förett lag av samverkande robotsystem är utformade. Deras antagnat dynamikär i kontinuerlig tid och olinjär. Problemet involverar agenter vars dynamik äroberoende av varandra, och sina lösning kopplar sina begränsningar som ettmedel för att fånga det kooperativa beteendet som krävs. Analytiska bevis gesför att visa att, enligt det föreslagna kontrollsystemet: (a) med förbehåll förförsta genomförbarhet, kommer optimeringen som löses vid varje steg av varjeagent alltid vara möjligt, oavsett huruvida störningar påverkar agenserna ellerinte. I det förre fallet är rekursiv genomförbarhet etablerad genom successivabegränsningar av varje agents inskränkning under den periodiska lösningentill dess respektive optimeringsproblem. (b) Varje (sub) system kan stabiliserastill en önskad konfiguration, antingen asymptotiskt när osäkerhet saknas,eller inom en närhet av det, när osäkerhet är närvarande, således dämparpåverkanstörning. I detta sammanhang antas störningar vara additiv och avgränsas.Simuleringar verifierar effekten av den föreslagna metoden över ettintervall av olika driftsmiljöer.
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Ahl, Philip. "Optimal Cooperative Platooning Using Micro-Transactions." Thesis, Uppsala universitet, Avdelningen för systemteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-417332.
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The urge to consume does not seem to stop, thus, the need for transportation of goods will most likely not decrease. At the same time jurisdictions and regulations around greenhouse gas emissions are sharpening and pushing the industry towards a more environmentally friendly state. The freight and transportation industry is facing a huge challenge in the upcoming years and solutions are needed to feed the demand of society. Two, of many, proposals of solving, at least, parts of the above mentioned problem is platooning and the look-ahead controller. Platooning denotes the concept of slipstream where maximum utilization of aerodynamic drag reduction is endeavoured. The lookahead controller exploits the surrounding topographical information in order to yield an optimal driving strategy, often resulting in that the vehicle initiates the phenomenon of pulse and glide, which denotes alternating between high load operation points and freewheeling, i.e. engaging neutral gear. This work has sought to investigate these concepts to determine whether or not additional fuel-efficiency can be added by manipulating and re-designing the control unit of the system. The proposed addition is built upon the look-ahead controller and supplements it by enabling communication between vehicles such that micro-transactions may occur in order to aid decision making regarding the choice of driving strategies. A vehicle model, a platoon model and the novel optimization based look-ahead-controller was synthesized and developed, where dynamic programming was used as the optimization solver of the controller. The look-ahead controller was verified such that one can conclude that it behaves according to the assumptions of such a system. The proposed micro-transaction system was also verified to conclude that it behaves as assumed, yielding a reduction in fuel consumption. For a platoon of two members, a 1.2% and 1.7% reduction in fuel consumption for the leading and following vehicle respectively was obtained, compared to an identical platooning setup, using a lookahead controller, but where no negotiations using micro-transactions are allowed between the vehicles.
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Kingston, Derek B. "Decentralized Control of Multiple UAVs for Perimeter and Target Surveillance." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/1174.
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With the recent development of reliable autonomous technologies for small unmanned air vehicles (UAVs), the algorithms utilizing teams of these vehicles are becoming an increasingly important research area. Unfortunately, there is no unified framework into which all (or even most) cooperative control problems fall. Five factors that affect the development of cooperative control algorithms are objective coupling, communication, completeness, robustness, and efficiency. We classify cooperative control algorithms by these factors and then present three algorithms with application to target and perimeter surveillance and a method for decentralized algorithm design. The primary contributions of this research are the development and analysis of decentralized algorithms for perimeter and target surveillance. We pose the cooperative perimeter surveillance problem and offer a decentralized solution that accounts for perimeter growth (expanding or contracting) and insertion/deletion of team members. By identifying and sharing the critical coordination information and by exploiting the known communication topology, only a small communication range is required for accurate performance. Convergence of the algorithm to the optimal configuration is proven to occur in finite-time. Simulation and hardware results are presented that demonstrate the applicability of the solution. For single target surveillance, a team of UAVs angularly spaced (i.e. in the splay state configuration) provides the best coverage of the target in a wide variety of circumstances. We propose a decentralized algorithm to achieve the splay state configuration for a team of UAVs tracking a moving target and derive the allowable bounds on target velocity to generate a feasible solution as well as show that, near equilibrium, the overall system is exponentially stable. Monte Carlo simulations indicate that the surveillance algorithm is asymptotically stable for arbitrary initial conditions. We conclude with high fidelity simulation and actual flight tests to show the applicability of the splay state controller to unmanned air systems.
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Radmanesh, Mohammadreza. "A Unified Framework for Multi- UAV Cooperative Control based on Partial Differential Equations." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1554475603011835.
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Ahsant, Babak. "PERFORMANCE OF COUNTING RULES FOR PRIMARY USER DETECTION." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/dissertations/1062.
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In this dissertation we consider the problem of cooperative sensing for secondary user access to primary user spectrum in cognitive radio systems. Using a fusion center or an access point, the cooperative users decide on the availability of spectrum for their use. Both Neyman-Pearson and Bayes criterion are considered for performance assessment. Our work on the asymptotic performance of counting rules with a very large number of sensors in decentralized detection problem shows that majority logic fusion rule has the same order of performance when compared to the best fusion rule based on the binary decisions received from the observing sensors in a network. In cognitive radio context, very large number of sensors may not be realistic and hence we would like to examine the performance of majority logic and counting rules involving a finite and small number of sensors. Uniformly most powerful test for decentralized detection for testing parameter θ when the observation is a sample from uniform (0,θ) distribution is investigated and it is shown that OR rule has the best performance among all counting rules in error free channel. The numerical study for reporting channel as a binary symmetric channel (BSC) with probability of bit error is also investigated and the results show that 2-out-of-5 or 2-out-of-10 has better performance among other k-out-of-n rules, whenever OR rule is not able to provide a probability of false alarm at the sensor, that lies over (0,1) at a given probability of bit error.
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de, Azevedo Ricardo. "Fully Decentralized Multi-Agent System for Optimal Microgrid Control." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2461.
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In preparation for the influx of renewable energy sources that will be added to the electrical system, flexible and adaptable control schemes are necessary to accommodate the changing infrastructure. Microgrids have been gaining much attention as the main solution to the challenges of distributed and intermittent generation, but due to their low inertia, they need fast-acting control systems in order to maintain stability. Multi-Agent Systems have been proposed as dynamic control and communication frameworks. Decentralized arrangements of agents can provide resiliency and the much-desired “plug and play” behavior. This thesis describes a control system that implements droop control and the diffusion communication scheme without the need of a centralized controller to coordinate the Microgrid agents to maintain the frequency and stable operating conditions of the system. Moreover, the inter-agent communication is unaffected by changing network configurations and can achieve optimal economic dispatch through distributed optimization.
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Bai, Chumeng. "Evaluation and Improvement of Decentralized Congestion Control for Multiplatooning Application." Thesis, KTH, Radio Systems Laboratory (RS Lab), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232849.
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Platooning has the potential to be a breakthrough in increasing road capacity and reducing fuel consumption, as it allows a chain of vehicles to closely follow each other on the road. When the number of vehicles increases, platoons will follow one another in what is referred to as multiplatooning. Many Cooperative Intelligent Transportation Systems (C-ITS) applications rely on periodically exchanged beacons among vehicles to improve traffic safety. However, as the number of connected vehicles increases, the network may become congested due to periodically exchanged beacons. Therefore, without some congestion control method, safety critical messages such as Cooperative Awareness Messages (CAMs) may not be delivered on time in high vehicle density scenarios. Both the European Telecommunications Standards Institute (ETSI) and the Institute of Electrical and Electronics Engineers (IEEE) have been working on different standards to support vehicular communication. ETSI dened the Decentralized Congestion Control (DCC) mechanism which adapts transmission parameters (message rate, transmit data rate, and transmit power, etc.) to keep channel load under control. ETSI DCC utilizes a three-state machine with RELAXED, ACTIVE, and RESTRICTIVE states. In this thesis, we implemented this three-state machine by adapting the message rate based on the channel busy ratio (CBR). We name this message-rate based three-state machine DCC-3. DCC-3 has the ability to control channel load; however, it has unfairness and instability problems due to the dramatic parameter changes between states. Therefore, we divided the ACTIVE state of DCC-3 into ve sub-states, and refer to this as DCC-7. We benchmarked DCC-3 against static beaconing (STB), dynamic beaconing (DynB), LInear MEssage Rate Integrated Control (LIMERIC), and DCC-7 using different evaluation metrics with different numbers of platoons. Our results from the Plexe simulator demonstrate that DCC-7 has the best performance when considering all evaluation metrics, including CBR, Inter-reception time (IRT), collisions, safe time ratio, and fairness. Furthermore, we found using transmit power control could greatly improve the performance of CBR and collision rates.<br>Platooning (fordonskonvojer) har potential att bli ett genombrott i öka vägkapaciteten och minska bränsleförbrukning, eftersom det tillåter en kedja av fordon att noga följa varandra på vägen. När antalet fordon ökar, kommer att plutoner följa varandra i vad som benämns multiplatooning (konvoj av fordonskonvojer). Många kooperativ intelligenta transportsystem (C-ITS) tillämpningar förlitar sig på regelbundet utbytte beacons bland fordon att förbättra traffiksäkerheten. Dock som antalet uppkopplade fordon ökar, kan nätverket bli överbelastat på grund av regelbundet utbytte beacons. Utan någon trängsel kontrollmetod, får därför säkerhet kritiska meddelanden såsom kooperativ medvetenhet meddelanden (CAMs) inte levereras i tid i höga fordon densitet scenarier. Både Europeiska institutet för telekommunikationsstandarder (ETSI) och Institute el och elektroniska tekniker (IEEE) har arbetat på olika standarder för att stödja vehicular kommunikation. ETSI definieras den decentraliserade överbelastning kontroll (DCC) mekanism som anpassar överföring parametrar (meddelande hastighet, överföra datahastighet och sändningseffekt, etc.) för att hålla kanalen belastningen under kontroll. ETSI DCC använder en tre-state maskin med RELAXED, ACTIVE och RESTRICTIVE stater. I denna avhandling har genomfört vi denna tre-state maskin genom att anpassa meddelande hastighet baserat på kanal upptagen förhållandet (CBR). Vi nämna detta meddelande-hastighet baserat tre-state machine DCC-3. DCC-3 har förmågan att kontrollera kanal belastning; Det har dock otillbörlighet och instabilitet problem på grund av de dramatiska parameterändringar mellan stater. Därför vi indelat det ACTIVE tillståndet för DCC-3 i fem undertillstånd och hänvisar till detta som DCC-7. Vi benchmarkade DCC-3 mot statiska leda (STB), dynamisk leda (DynB), linjära MEssage Rate integrerad kontroll (LIMERIC) och DCC-7 med olika utvärdering statistik med olika antal plutoner. Våra resultat från Plexe simulator visar att DCC-7 har bästa prestanda när man överväger alla utvärdering statistik, inklusive CBR, mellan receptionen tid (IRT), kollisioner, säker tid baserat och rättvisa. Vi fann dessutom använda Sändareffektstyrning kan avsevärt förbättra prestanda för CBR och kollision priser.
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Liao, Yan. "Decentralized Decision Making and Information Sharing in a Team of Autonomous Mobile Agents." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353101024.
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Roberson, David Gray. "Environmental Tracking and Formation Control for an Autonomous Underwater Vehicle Platoon with Limited Communication." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26175.
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A platoon of autonomous underwater vehicles provides a compelling platform for studying many challenging issues in multi-agent cooperative control. These challenges include developing cooperative algorithms suitable to practical multi-vehicle applications. They also include addressing intervehicle communication issues, such as sharing information via limited bandwidth channels and selecting network architecture to facilitate control design. This work addresses problems in each of these areas.
Environmental tracking and formation control serves as the main application upon which this work focuses. In the tracking and formation control application, a team of vehicles obtains a spatial average of an environmental feature by collecting and sharing local measurements. To achieve this objective, vehicles track a desired environmental field contour with their average position while maintaining a desired spatial formation about the average. A decentralized consensus-based algorithm is developed for controlling the platoon. In a novel two-level consensus approach, each vehicle estimates a virtual leader trajectory using local and shared measurements at one level, then positions itself about the virtual leader at a second level.
Due to very low bandwidth underwater communication, vehicles share information intermittently, and the platoon network is effectively disconnected at every instant of time. This issue is addressed by modeling the platoon as a periodic switched system whose frozen-time subsystems possess disconnected networks, but whose time-averaged system is connected. The stability and input-output properties of the switched system are related to those of the corresponding average system. Under sufficiently fast switching, asymptotic stability of the average system implies asymptotic stability of the switched system and the existence of an L2 gain. Estimates of the slowest stabilizing switching rate and the L2 gain are derived.
Controller and estimator design are complicated by the lack of a separation principle for decentralized systems and by the effects of intervehicle coupling. The potential for choosing the communication topology in a manner that leads to design simplifications is investigated. In particular, a transformation is presented that converts the platoon state coefficient matrix to block diagonal form when the communication network has a circulant structure.<br>Ph. D.
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Ge, Feng. "Software Radio-Based Decentralized Dynamic Spectrum Access Networks: A Prototype Design and Enabling Technologies." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/29981.
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Dynamic spectrum access (DSA) wireless networks focus on using RF spectrum more efficiently and dynamically. Significant progress has been made during the past few years. For example, many measurements of current spectrum utilization are available. Theoretical analyses and computational simulations of DSA networks also abound. In sharp contrast, few network systems, particularly those with a decentralized structure, have been built even at a small scale to investigate the performance, behavior, and dynamics of DSA networks under different scenarios. This dissertation provides the theory, design, and implementation of a software radio-based decentralized DSA network prototype, and its enabling technologies: software radio, signal detection and classification, and distributed cooperative spectrum sensing.
By moving physical layer functions into the software domain, software radio offers an unprecedented level of flexibility in radio development and operation, which can facilitate research and development of cognitive radio (CR) and DSA networks. However, state-of-the-art software radio systems still have serious performance limitations. Therefore, a performance study of software radio is needed before applying it in any development. This dissertation investigates three practical issues governing software radio performance that are critical in DSA network development: RF front end nonlinearity, dynamic computing resource allocation, and execution latency. It provides detailed explanations and quantitative results on SDR performance.
Signal detection is the most popular method used in DSA networks to guarantee non-interference to primary users. Quickly and accurately detecting signals under all possible conditions is challenging. The cyclostationary feature detection method is attractive for detecting primary users because of its ability to distinguish between modulated signals, interference, and noise at a low signal-to-noise ratio (SNR). However, a key issue of cyclostationary signal analysis is the high computational cost. To tackle this challenge, parallel computing is applied to develop a cyclostationary feature based signal detection method. This dissertation presents the methodâ s performance on multiple signal types in noisy and multi-path fading environments.
Distributed cooperative spectrum sensing is widely endorsed to monitor the radio environment so as to guarantee non-interference to incumbent users even at a low SNR and under hostile conditions like shadowing, fading, interference, and multi-path. However, such networks impose strict performance requirements on data latency and reliability. Delayed or faulty data may cause secondary users to interfere with incumbent users because secondary users could not be informed quickly or reliably. To support such network performance, this dissertation presents a set of data process and management schemes in both sensors and data fusion nodes. Further, a distributed cooperative sensor network is built from multiple sensors; together, the network compiles a coherent semantic radio environment map for DSA networks to exploit available frequencies opportunistically.
Finally, this dissertation presents the complete design of a decentralized and asynchronous DSA network across the PHY layer, MAC layer, network layer, and application layer. A ten-node prototype is built based on software radio technologies, signal detection and classification methods, distributed cooperative spectrum sensing systems, dynamic wireless protocols, and a multi-channel allocation algorithm. Systematic experiments are carried out to identify several performance determining factors for decentralized DSA networks.<br>Ph. D.
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Tunaru, Iulia. "Physical layer secret key generation for decentralized wireless networks." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S081/document.
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Dans cette thèse on s’est intéressé aux méthodes de génération de clés secrètes symétriques en utilisant la couche physique ultra large bande impulsionnelle (IR-UWB). Les travaux ont été réalisés selon trois axes, les deux premiers concernant la communication point-à-point et le dernier, les communications coopératives. Tout d’abord, la quantification des signaux typiques IR-UWB (soit directement échantillonnés, soit estimés) a été investiguée, principalement du point de vue du compromis entre la robustesse (ou réciprocité) des séquences binaires obtenues et leur caractère aléatoire. Différents algorithmes de quantification valorisant l’information temporelle offerte par les canaux IR-UWB pour améliorer ce compromis ont alors été proposés. Ensuite, des études concernant les échanges publics nécessaires à l’étape de réconciliation (visant la correction d’éventuels désaccords entre les séquences binaires générées de part et d’autre du lien) ont montré qu’il était possible d’être plus robuste face aux attaques passives en utilisant des informations de plus haut niveau, inhérentes à cette technologie et disponibles à moindre coût (ex. via une estimation précise du temps de vol aller-retour). Finalement, une nouvelle méthode a été développée afin d’étendre les schémas de génération de clé point-à-point à plusieurs nœuds (trois dans nos études) en utilisant directement la couche physique fournie par les liens radio entre les nœuds<br>Emerging decentralized wireless systems, such as sensor or ad-hoc networks, will demand an adequate level of security in order to protect the private and often sensitive information that they carry. The main security mechanism for confidentiality in such networks is symmetric cryptography, which requires the sharing of a symmetric key between the two legitimate parties. According to the principles of physical layer security, wireless devices within the communication range can exploit the wireless channel in order to protect their communications. Due to the theoretical reciprocity of wireless channels, the spatial decorrelation property (e.g., in rich scattering environments), as well as the fine temporal resolution of the Impulse Radio - Ultra Wideband (IR-UWB) technology, directly sampled received signals or estimated channel impulse responses (CIRs) can be used for symmetric secret key extraction under the information-theoretic source model. Firstly, we are interested in the impact of quantization and channel estimation algorithms on the reciprocity and on the random aspect of the generated keys. Secondly, we investigate alternative ways of limiting public exchanges needed for the reconciliation phase. Finally, we develop a new signal-based method that extends the point-to-point source model to cooperative contexts with several nodes intending to establish a group key
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Xu, Xiaozhou. "Mécanisme de collaboration dans la collaboration logistique horizontale." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2013. http://pastel.archives-ouvertes.fr/pastel-00957302.
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À cause des stratégies de production et de marketing de plus en plus ambitieuses tellesque le Juste-À-Temps et la production adaptée au client, les approches de collaboration logistique verticale qui sont courantes atteignent une limite d'efficacité notamment en transport. La collaboration logistique horizontale (CLH) et plus particulièrement la mutualisation, dont l'efficacité a été prouvée dans la littérature et dans les cas réels, a attiré l'attention des chercheurs ainsi que des praticiens. Cependatn, un des obstacles principaux à la mise en œuvre des CLHs est l'absence d'un mécanisme de collaboration raisonné, en particulier un mécanisme de partage des gains. Nous identifions deux formes d'organisation des CLHs : centralisée limité en pratique à de petites coalitions et décentralisée pouvant comprendre de nombreux participants. Pour des CLHs centralisées, nous proposons un modèle de collaboration qui est un processus de conduite qui intègre les outils d'aide à la décision. Nous développons également un mécanisme de partage par la théorie des jeux. Ce mécanisme est applicable aux différentes catégories des CLHs centralisées, qui peuvent être modélisées par des jeux coopératifs super-additif et non-super-additifs. Afin de proposer un plan de partage crédible aux collaborateurs, ce mécanisme de partage prend en compte la contribution de chacun des collaborateurs, la stabilité de la coalition et leur pouvoir de négociation. Ce cadre est illustré par des exemples numériques issus de cas logistiques. Pour la mise en œuvre des CLHs décentralisées, nous proposons un cadre de travail de logistique collaborative qui est ouvert aux participants potentiels, et avons conçu des protocoles fondés sur le mécanisme d'enchère combinatoire, qui spécifient l'allocation de demande de livraison et la détermination de paiement pour faciliter les collaborations. Cette dernière partie s'appuie sur la théorie dite de Mechanism design.
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Lai, Yi-Sheng, and 賴易聖. "Decentralized Congestion Control for Cooperative Safety Applications." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/86982613891977138431.
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碩士<br>國立交通大學<br>網路工程研究所<br>103<br>Congestion control is an important issue in vehicular networks. The loss of messages due to congestion may cause seriously deteriorate to the reliability of Intelligent Transportation System (ITS) especially for safety applications.
European Telecommunications Standards Institute (ETSI) has specified a set of Decentralized Congestion Control (DCC) standards. DCC is a cross-layer protocol across Access layer, Network &;Transport layer, Facilities layer, and Management layer in ETSI TC-ITS. So far ETSI mainly focused on Access layer DCC and is lack of discussion on the Facilities layer issues. The task of Facilities layer DCC is to allocate available channel resource to vehicles with fairness assumption, dividing total channel resource equally amongst vehicles in the channel. However, this mechanism is not adaptive to safety applications where vehicles may have different priorities in terms of emergency.
In this thesis, we proposed a channel resource allocation mechanism for the Facilities layer DCC. The mechanism takes account of needed and feature of Forward Collision Warning (FCW) application. Simulation results show that the proposed method can improve the performance of FCW compared to existing mechanism.
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Jain, Ravinder Praveen Kumar. "Decentralized Cooperative Control Methods for Multiple Mobile Robotic Vehicles." Tese, 2019. https://hdl.handle.net/10216/121530.
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Jain, Ravinder Praveen Kumar. "Decentralized Cooperative Control Methods for Multiple Mobile Robotic Vehicles." Doctoral thesis, 2019. https://hdl.handle.net/10216/121530.
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Weitz, Lesley A. "Decentralized, Cooperative Control of Multivehicle Systems: Design and Stability Analysis." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-696.
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This dissertation addresses the design and stability analysis of decentralized, cooperative
control laws for multivehicle systems. Advances in communication, navigation,
and surveillance systems have enabled greater autonomy in multivehicle systems, and
there is a shift toward decentralized, cooperative systems for computational efficiency
and robustness. In a decentralized control scheme, control inputs are determined
onboard each vehicle; therefore, decentralized controllers are more efficient for large
numbers of vehicles, and the system is more robust to communication failures and
reconfiguration.
The design of decentralized, cooperative control laws is explored for a nonlinear
vehicle model that can be represented in a double-integrator form. Cooperative controllers
are functions of spacing errors with respect to other vehicles in the system,
where the communication structure defines the information that is available to each
vehicle. Control inputs are selected to achieve internal stability, or zero steady-state
spacing errors, between vehicles in the system.
Closed-loop equations of motion for the cooperative system can be written in a
structural form, where damping and stiffness matrices contain control gains acting on
the velocity and positions of the vehicles, respectively. The form of the stiffness matrix
is determined by the communication structure, where different communication structures yield different control forms. Communication structures are compared using
two structural analysis tools: modal cost and frequency-response functions, which
evaluate the response of the multivehicle systems to disturbances. The frequency-response
information is shown to reveal the string stability of different cooperative
control forms.
The effects of time delays in the feedback states of the cooperative control laws
on system stability are also investigated. Closed-loop equations of motion are modeled
as delay differential equations, and two stability notions are presented: delay-independent
and delay-dependent stability.
Lastly, two additional cooperative control forms are investigated. The first control
form spaces vehicles along an arbitrary path, where distances between vehicles
are constant for a given spacing parameter. This control form shows advantages over
spacing vehicles using control laws designed in an inertial frame. The second control
form employs a time-based spacing scheme, which spaces vehicles at constant-time
intervals at a desired endpoint. The stability of these control forms is presented.
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Izadi, Hojjat A. "Decentralized receding horizon control of cooperative vehicles with communication delays." Thesis, 2009. http://spectrum.library.concordia.ca/976694/1/NR67324.pdf.
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This thesis investigates the decentralized receding horizon control (DRHC) for a network of cooperative vehicles where each vehicle in the group plans its future trajectory over a finite prediction horizon time. The vehicles exchange their predicted paths with the neighbouring vehicles through a communication channel in order to maintain the cooperation objectives. In this framework, more frequent communication provides improved performance and stability properties. The main focus of this thesis is on situations where large inter-vehicle communication delays are present. Such large delays may occur due to fault conditions with the communication devices or limited communication bandwidth. Large communication delays can potentially lead to poor performance, unsafe behaviour and even instability for the existing DRHC methods. The main objective of this thesis is to develop new DRHC methods that provide improved performance and stability properties in the presence of large communication delays. Fault conditions are defined and diagnosis algorithms are developed for situations with large communication delays. A fault tolerant DRHC architecture is then proposed which is capable of effectively using the delayed information. The main idea with the proposed approach is to estimate the path of the neighbouring faulty vehicles, when they are unavailable due to large delays, by adding extra decision variables to the cost function. It is demonstrated that this approach can result in significant improvements in performance and stability. Furthermore, the concept of the tube DRHC is proposed to provide the safety of the fleet against collisions during faulty conditions. In this approach, a tube shaped trajectory is assumed in the region around the delayed trajectory of the faulty vehicle instead of a line shaped trajectory. The neighbouring vehicles calculate the tube and are not allowed to enter that region. Feasibility, stability, and performance of the proposed fault tolerant DRHC are also investigated. Finally, a bandwidth allocation algorithm is proposed in order to optimize the communication periods so that the overall teaming performance is optimized. Together, these results form a new and effective framework for decentralized receding horizon control with communication faults and large communication delays.
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Zhang, Yu-wei, and 張育瑋. "Decentralized Reception Technique using Punctured Codes for Cooperative Communication Systems." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/a9gh77.
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碩士<br>國立中山大學<br>通訊工程研究所<br>103<br>Using decentralized relays to help signals transmission for cooperative communication systems can extend the transmission distance effectively and prevent the degradation of the system performance caused by channel fading. It only affects the individual transmission channel when a path in the cooperative network fails. As a result, using decentralized relays increases the systems reliability and reduces the decoded error rates in the fusion center.
This thesis mainly investigates the performance of the cooperative communications networks using coding approach. Specifically, this thesis proposes to employ a punctured codes in the system, in which the decentralized relays and the destination are operated using coding reception techniques. The results obtained by the thesis show that the system employing punctured codes outperforms the systems using the coding approach in the existing works. Moreover, the proposed approach also consumes less energy as compared with the system without using
punctured codes.
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Peng, Zhao-Ping, and 彭兆平. "Decentralized Cooperative Bank Electronic Payment System Based on Blockchain Technology." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5396008%22.&searchmode=basic.
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碩士<br>國立中興大學<br>資訊管理學系所<br>107<br>In the past, the most common consuming behavior was traded by cash at a physical store. In recent years, with the rapid development and popularity of smart handheld devices and computers, merchants have many innovative business models. For example, online shopping malls such as Shopee. The convenience and speed online transactions have gradually changed people''s habits. This trend has also made electronic payment have great potential for development.
There are several types of electronic payments such as electronic cash, electronic wallets, smart cards, etc. The most common ones are EasyCard, LINE Pay or Apple Pay. Users can choose the payment method they want to use and pay via Radio Frequency Identification (RFID) or Near Field Communication (NFC). For example, buyers and sellers must register with an electronic payment institution and store the value in a bank''s special deposit account via a payment instrument such as ATM, online banking or bank counter. These deposit records will also be recorded in the personal electronic payment account.
Blockchain is a technology used in the underlying cryptocurrency system of Bitcoin. It is a technology for accessing, verifying and transmitting network data through distributed nodes. It uses a peer-to-peer network to achieve a decentralized data storage platform. There is no need for a decentralized system that is based on mutual trust and does not rely on a single centralized organization to operate. The identity verification and security uses Public Key Infrastructure to achieve. Each account in the blockchain will have a public key and a private key. When the transaction is performed, the sender''s private key is used to encrypt the transaction message, and the receiver uses the sender''s public key to decrypt the message to confirm the message integrity, so there will be no forged messages in the blockchain. The preservation and connection of blockchain data are using cryptography to establish a computational link relationship between data and data to achieve the immutability and integrity of the data. If combining the advantages of the Bitcoin system with the financial operating model of today''s electronic payments will be very disruptive and innovative. However, the use of blockchain technology, decentralized network architecture, etc. In the financial system will face challenges such as anonymous crime, large data synchronization, and time-consuming transaction processes.
In order to improve the above defects and Implement in to the real electronic payment system, this thesis realizes the P2P electronic payment system CBP2P (Cooperative Bank Peer-to-Peer) of the hierarchical structure base on blockchain. Through the characteristics of the blockchain and cooperation between banks to ensure the security and operation of the system.
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Tan, Ye-Min, and 陳奕名. "Fuzzy Decentralized Cooperative Global Localization for a Multi-Ballbot System." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/92627527418107356806.
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碩士<br>國立中興大學<br>電機工程學系所<br>104<br>This thesis presents two cooperative global localizationmethods usingfuzzy decentralized extended information filtering (FDEIF) and fuzzy decentralized extended Kalman filtering (FDEKF) for a multi-ballbot system composed of several ballbots. When any known landmarks or QR codes are detect by a RGB-D sensor in a ballbot, a pose initialization algorithm is proposed to estimate both start-up positions and orientations of the ballbot, and acooperative localization method is proposed to find initial poses of other ballbots that can be directly detected by a laser scanner mounted at thelocalized ballbot. Once the initial global posesof all ballbots have been roughly determined,both FDEIF and FDEKF dynamic cooperative localization methodsare presented to fuse external measurements from oneRGB-D sensor, or one laser scanner and the four encoders mounted on each ballbot, in order to keep track of the moving poses of all the ballbotscontinuously and precisely. Several simulations and experiments are conducted to show that the proposed methodsare effective in finding accurate estimation of both unknown initial and continuous moving poses of a multi-ballbot system with threefollower ballbots.
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Yu-ChiangWang and 王育強. "A Fast Relay Selection Protocol in Decentralized Cooperative Wireless Networks." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/70286016651321565438.
Full textAbstract:
碩士<br>國立成功大學<br>電腦與通信工程研究所<br>98<br>In cooperative wireless network, selecting suitable relay nodes is critical to the achievable gain, including error rate, throughput and so on. The relay selection protocol will also effect the resulting due to the delay in relay selection. How to balance to trade-off between performance improvement and delay penalty thus needs to be carefully addressed. In this thesis, we propose a fast relay selection protocol. We let relay nodes to compete for the channel access during the relay selection phase leading to completely distributed relay selection. The relay nodes utilize instantaneous channel information to decide its action. In this thesis, we derive the expression of average delay time and outage probability. From the numerical results, we demonstrate the proposed scheme can significantly reduce the relay selection time and maintain a low outage probability.
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König, André. "Security in Infrastructure-less and Decentralized Communication Networks : Location-based Intrusion Response and User-based Cooperative Decisions." Phd thesis, 2011. http://tuprints.ulb.tu-darmstadt.de/2390/1/Andre_Koenig___Security_in_Infrastructure-less_and_Decentralized_Communication_Networks___2011.01.12.pdf.
Full textAbstract:
Infrastructure-less communication substrates like multi-hop wireless mobile ad hoc networks in combination with applications based on decentralized networks like peer-to-peer networks facilitate establishing digital communication services in a spontaneous way. Envisioned application scenarios include, for example, enabling communication in large-scale disaster scenarios. Here, a preexisting communication infrastructure might not be available. Thus, devices have to act both as communication endpoints and routers. Built upon the paradigm of self-organization, the functionality of both infrastructure-less and decentralized networks is based on the cooperation of the devices forming the network and on the abandonment of fixed, central instances. From the perspective of security, being able to establish selforganizing networks in a spontaneous way is, however, paid for by being dependent on the cooperation of devices from many administrative domains that are beyond a central control. Further, the availability of security policies controlling, for example, access to restricted resources can not be assumed during spontaneous interactions. In this thesis, we address two major resulting challenges of (1) maintaining the functionality of the network in presence of devices that exploit the cooperative nature of infrastructure-less networks to launch attacks on network availability and (2) achieving security objectives like authentication and access control in the absence of a central (trusted) instance and predefined security policies. Regarding Challenge (1), we present a novel, location-based intrusion response mechanism for infrastructure-less networks. Since devices in infrastructure-less networks are beyond a central control, changing network addresses of devices and, thus, circumventing conventional address-based intrusion response solutions is possible with little effort. The location-based intrusion response approach we develop within this thesis, instead, uses the physical location of devices as an identifier. Misbehaving devices are excluded from the network by establishing quarantined areas void of communication at locations where misbehavior is detected. Our results based on analytical modeling and simulation studies show that, this way, we render the intrusion response mechanism insusceptible to changes in addresses of misbehaving nodes. On the downside, benign devices located in close physical proximity to misbehaving nodes are, for the sake of overall network survivability, excluded from the network along with misbehaving nodes. To mitigate this effect, we propose two approaches based on (a) adaptive transmission power of devices to minimize the size of quarantined areas and (b) harnessing delay tolerance of applications to enable (delayed) communication of benign devices located within quarantined areas. Our results based on simulation studies show that an adaptive transmission power can improve the location-based intrusion response approach in scenarios with low node mobility. By harnessing delay tolerance, we are able to effectively support the location-based intrusion response at the cost of increased transmission delays. Regarding Challenge (2), we present user-based, cooperative decisions as a replacement for central (trusted) instances and security policies. By introducing a cooperative decision process based on threshold cryptography, we prevent that cryptographic operations like signing certificates that grant access to restricted resources can be performed by a single, possibly compromised device. By involving (authorized) users directly in the decision process, we enable decisions on security-related requests during spontaneous interactions without predefined security policies. When involving users directly in decision processes, obviously, the number of users, as well as the frequency at which one particular user is requested, have to be minimized. To achieve these requirements, we discuss different interaction schemes between a user issuing a security-related request and the (potential) users taking part in the decision process. Subsequently, we present analytical models serving as tools for governing the decision process, in order to minimize the number of users involved in a decision. Our results obtained from a prototype for user-based, cooperative decisions deployed in two testbeds show the applicability of the interaction schemes as well as the correctness of the analytical models.
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Yang, Guo-Hwa, and 楊國華. "Cooperative Global Pose Estimation and Localization for a Heterogeneous Omnidirectional Multirobot System Using Fuzzy Distributed and Decentralized Filtering." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/s4g2w4.
Full textAbstract:
碩士<br>國立中興大學<br>電機工程學系所<br>106<br>Abstract
This paper presents two cooperative global localization methods using fuzzy distributed and decentralized extended information filtering (FDDEIF) and fuzzy distributed and decentralized extended Kalman filtering (FDDEKF) for a heterogeneous omnidirectional multi-robots (HOMRs) system. This type HOMR system is composed of a car-like four-wheeled SWOR，a three-wheeled SWOR and a four-wheeled SWOR, where the communication topology is not completely connected to each other. When any known landmarks or QR codes are detect by a Kinect sensor in a heterogeneous robot, a pose initialization algorithm is proposed to estimate both start-up positions and orientations of that robot. Afterwards, a cooperative localization method is proposed to find initial poses of other heterogeneous robots that can be directly detected by a laser scanner mounted at the localized robot. Once the initial global poses of all heterogeneous robots have been roughly determined, both FDDEIF and FDDEKF cooperative localization methods are presented to fuse external measurements from one Kinect sensor, or one laser scanner and two encoders mounted on each heterogeneous robot, in order to keep track of the moving poses of all the heterogeneous robots continuously and precisely. Several simulations are conducted to show that the proposed methods are effective in finding accurate estimation of both unknown initial and continuous moving poses of a heterogeneous multi-robot system with three follower heterogeneous robots.
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Dao, Thanh-Son. "A Decentralized Approach to Dynamic Collaborative Driving Coordination." Thesis, 2008. http://hdl.handle.net/10012/3927.
Full textAbstract:
This thesis presents a novel approach to several problems in
intelligent transportation systems using collaborative driving
coordination. With inter-vehicle communication and intelligent
vehicle cooperation, important tasks in transportation such as lane
position determination, lane assignment and platoon formation can be
solved. Several topics in regard to inter-vehicle communication,
lane positioning, lane assignment and platoon formation are explored
in this thesis:
First, the design and experimental results of low-cost lane-level
positioning system that can support a large number of transportation
applications are discussed. Using a Markov-based approach based on
sharing information among a group of vehicles that are traveling
within the communication range of each other, the lane positions of
vehicles can be determined. The robustness effectiveness of the
system is shown in both simulations and real road tests.
Second, a decentralized approach to lane scheduling for vehicles
with an aim to increase traffic throughput while ensuring the
vehicles exit successfully at their destinations is presented. Most
of current traffic management systems do not consider lane
organization of vehicles and only regulate traffic flows by
controlling traffic signals or ramp meters. However, traffic
throughput and efficient use of highways can be increased by
coordinating driver behaviors intelligently. The lane optimization
problem is formulated as a linear programming problem that can be
solved using the Simplex method.
Finally, a direction for cooperative vehicle platoon formation is
proposed. To enhance traffic safety, increase lane capacities and
reduce fuel consumption, vehicles can be organized into platoons
with the objective of maximizing the travel distance that platoons
stay intact. Toward this end, this work evaluates a proposed
strategy which assigns vehicles to platoons by solving an
optimization problem. A linear model for assigning vehicles to
appropriate platoons when they enter the highway is formulated.
Simulation results demonstrate that lane capacity can be increased
effectively when platooning operation is used.
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König, André [Verfasser]. "Security in infrastructure-less and decentralized communication networks : location-based intrusion response and user-based cooperative decisions / von André König." 2011. http://d-nb.info/1009900269/34.
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EricYonathan and 陳利勇. "A Two-Step Computation Strategy for Designing Decentralized Supply Chains with Fair Profit Allocation Plans Using Nash Cooperative Bargaining Model." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/98yf83.
Full textAbstract:
碩士<br>國立成功大學<br>化學工程學系<br>107<br>Traditional supply-chain management methods often treated the given system as a whole, without considering the conflicting interests of its participants. Game theory was adopted in a number of prior studies to identify fair prices and throughputs of the intermediates so as to maintain sustainable operations. In particular, the mathematical frameworks of a series of fictitious systems have already been proposed in the literature. The proper designs of distributed processing systems were generated to facilitate implementation of a decentralized optimization strategy. In these supply chains, the supplier-produced intermediates were bought by consumers to manufacture the final products. However, when the total profit of a supply chain is maximized without constraints, the maximum total profit may not be divided and allocated to every actor fairly. This deficiency could lead to various negative impacts, including dissatisfaction of actors, instability of coalition, loss of markets, and reduction in revenue. For this reason, a cooperative game theory has already been applied to generate fair-profit allocation plans among the supplier(s) and consumer(s) so as to establish a long-term working relationship. The present work developed a two-step approach addresses this issue. Finding the maximum total profit of the whole chain is the primary task of the first step, while the Nash cooperative bargaining approach is adopted in the second step so as to distribute the total profit among the actors fairly. Consequently, the corresponding intermediate prices and throughputs can also be estimated as well. Various case studies in fictitious systems and the petroleum supply chain are provided as examples to demonstrate the feasibility of the proposed approach. It can be observed from the optimization results of various case studies in fictitious systems and the petroleum supply chain that the goal to get the fair profit allocation plans can be achieved while still maintaining the maximum total profit of the whole chain.
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Rajab, Fat-Hy Omar. "Swarm Localization and Control via On-board Sensing and Computation." Thesis, 2019. http://hdl.handle.net/10754/656197.
Full textAbstract:
Multi-agent robotic system have been proved to be more superior in undertaking
functionalities, arduous or even impossible when performed by single agents. The
increased e ciency in multi agent systems is achieved by the execution of the task
in cooperative manner. But to achieve cooperation in multi agent systems, a good
localization system is an important prerequisite. Currently, most of the multi-agent
system rely on the use of the GPS to provide global positioning information which
su ers great deterioration in performance in indoor applications, and also all to all
communication between the agents will be required which is not e cient especially
when the number of agents is large. In this regard, a real-time localization scheme
is introduced which makes use of the robot's on-board sensors and computational
capabilities to determine the states of other agents in the multi agent system. This
algorithm also takes the advantage of the swarming behaviour of the robots in the
estimation of the states. This localization algorithm was found to produce more
accurate agent state estimates as compared to a similar localization algorithm that
does not take into account the swarming behaviour of the agents in simulations and
real experiment involving two Unmanned Aerial Vehicles.