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51
Distributed control of robotic networks: a mathematical approach to motion coordination algorithms
, 2009
"... (i) You are allowed to freely download, share, print, or photocopy this document. (ii) You are not allowed to modify, sell, or claim authorship of any part of this document. (iii) We thank you for any feedback information, including errors, suggestions, evaluations, and teaching or research uses. 2 ..."
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Cited by 41 (1 self)
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(i) You are allowed to freely download, share, print, or photocopy this document. (ii) You are not allowed to modify, sell, or claim authorship of any part of this document. (iii) We thank you for any feedback information, including errors, suggestions, evaluations, and teaching or research uses. 2 “Distributed Control of Robotic Networks ” by F. Bullo, J. Cortés and S. Martínez
Sensor networks with random links: Topology design for distributed consensus
 IEEE Trans. on Signal Processing, http://arxiv.org/PS cache/arxiv/pdf/0704/0704.0954v1.pdf
, 2007
"... In a sensor network, in practice, the communication among sensors is subject to: (1) errors or failures at random times; (2) costs; and (3) constraints since sensors and networks operate under scarce resources, such as power, data rate, or communication. The signaltonoise ratio (SNR) is usually a ..."
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Cited by 38 (15 self)
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In a sensor network, in practice, the communication among sensors is subject to: (1) errors or failures at random times; (2) costs; and (3) constraints since sensors and networks operate under scarce resources, such as power, data rate, or communication. The signaltonoise ratio (SNR) is usually a main factor in determining the probability of error (or of communication failure) in a link. These probabilities are then a proxy for the SNR under which the links operate. The paper studies the problem of designing the topology, i.e., assigning the probabilities of reliable communication among sensors (or of link failures) to maximize the rate of convergence of average consensus, when the link communication costs are taken into account, and there is an overall communication budget constraint. To consider this problem, we address a number of preliminary issues: (1) model the network as a random topology; (2) establish necessary and sufficient conditions for mean square sense (mss) and almost sure (a.s.) convergence of average consensus when network links fail; and, in particular, (3) show that a necessary and sufficient condition for both mss and a.s. convergence is for the algebraic connectivity of the mean graph describing the network topology to be strictly positive. With these results, we formulate topology design, subject to random link failures and to a communication cost constraint, as a constrained convex optimization problem to which we apply semidefinite programming techniques. We show by an extensive numerical study that the optimal design improves significantly the convergence speed of the consensus algorithm and can achieve the asymptotic performance of a nonrandom network at a fraction of the communication cost.
Consensus based overlapping decentralized estimation with missing observations and communication faults
 Automatica
, 2009
"... Abstract—In this technical note a new algorithm for state estimation is proposed in the form of a multiagent network based on a synergy between local Kalman filters and a dynamic consensus strategy between the agents. It is shown that it is possible, under general conditions concerning local resour ..."
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Cited by 24 (1 self)
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Abstract—In this technical note a new algorithm for state estimation is proposed in the form of a multiagent network based on a synergy between local Kalman filters and a dynamic consensus strategy between the agents. It is shown that it is possible, under general conditions concerning local resources and the network topology, to achieve asymptotic stability of the whole estimation algorithm by a proper choice of the consensus gains. It is demonstrated that the consensus gains can be obtained by minimizing the total meansquare estimation error. Capabilities of the network to achieve reduction of the measurement noise influence are also discussed. Index Terms—Consensus strategy, decentralized estimation, multiagent systems, optimization, overlapping decompositions, stability analysis. I.
The N k Problem in Power Grids: New Models, Formulations and Numerical Experiments
, 2008
"... Given a power grid modeled by a network together with equations describing the power flows, power generation and consumption, and the laws of physics, the socalled N − k problem asks whether there exists a set of k or fewer arcs whose removal will cause the system to fail. The case where k is small ..."
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Cited by 24 (1 self)
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Given a power grid modeled by a network together with equations describing the power flows, power generation and consumption, and the laws of physics, the socalled N − k problem asks whether there exists a set of k or fewer arcs whose removal will cause the system to fail. The case where k is small is of practical interest. We present theoretical and computational results involving a mixedinteger model and a continuous nonlinear model related to this question.
Improving connectivity via relays deployment in wireless sensor networks
 Proc. IEEE Global Telecommunications Conference (Globecom’07
, 2007
"... Abstract — Enhancing the connectivity of wireless sensor networks is necessary to avoid the occurrence of coverage gaps. In this paper, we aim at improving the network connectivity of a given network by adding a set of relays to it. We characterize the network connectivity by the Fiedler value, whic ..."
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Cited by 17 (2 self)
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Abstract — Enhancing the connectivity of wireless sensor networks is necessary to avoid the occurrence of coverage gaps. In this paper, we aim at improving the network connectivity of a given network by adding a set of relays to it. We characterize the network connectivity by the Fiedler value, which is the second smallest eigenvalue of the Laplacian matrix representing the network graph. We propose a networkmaintenance algorithm, which finds the best locations for a given set of relays. The proposed algorithm obtains the best relays ’ locations through a multilevel approach. In each level, the search problem can be formulated as a standard semidefinite programming (SDP) optimization problem. We show that the proposed algorithm can increase the average Fiedler value by 35 % by adding one relay only. I.
Design and Optimization of a Tiered Wireless Access Network
"... Abstract—Although having high potential for broadband wireless access, wireless mesh networks are known to suffer from throughput and fairness problems, and are thus hard to scale to large size. To this end, hierarchical architectures provide a solution to this scalability problem. In this paper, w ..."
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Cited by 9 (8 self)
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Abstract—Although having high potential for broadband wireless access, wireless mesh networks are known to suffer from throughput and fairness problems, and are thus hard to scale to large size. To this end, hierarchical architectures provide a solution to this scalability problem. In this paper, we address the problem of design and optimization of a tiered wireless access network. At the lower tier, mesh routers are clustered based on traffic demands and delay requirements. The cluster heads are equipped with wireless optical transceivers and form the upper tier free space optical (FSO) network. We first present a plane sweeping and clustering algorithm aiming to minimize the number of clusters. PSC sweeps the network area and captures cluster members under delay and traffic load constraints. We then present an algebraic connectivitybased formulation for FSO network topology optimization and develop a greedy edgeappending algorithm that iteratively inserts edges to maximize algebraic connectivity. The proposed algorithms are analyzed and evaluated via simulations, and are shown to be highly effective as compared to the performance bounds derived in this paper. I.
Stoorvogel A. A design for multileadcompensators for stabilization and pole placement in doubleintegrator networks
 Proceedings of the 2009 American Control Conference, St
, 2009
"... Abstract—We study decentralized controller design for stabilization and poleplacement, in a network of autonomous agents with doubleintegrator internal dynamics and arbitrary observation topology. We show that a simple multileadcompensator architecture, in particular one in which each agent use ..."
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Cited by 6 (6 self)
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Abstract—We study decentralized controller design for stabilization and poleplacement, in a network of autonomous agents with doubleintegrator internal dynamics and arbitrary observation topology. We show that a simple multileadcompensator architecture, in particular one in which each agent uses a derivativeapproximation compensator with three memory elements, can achieve both stabilization and effective pole placement while subdividing complexity/actuation among the agents. Through a scaling argument, we also demonstrate that the multileadcompensator can stabilize the doubleintegrator network under actuator saturation constraints. Index Terms—Decentralized control, lead compensator, pole placement, saturation, stabilization. I.
Connectivityaware network maintenance and repair via relays deployment
 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
, 2009
"... Abstract—In this paper we address the network maintenance problem, in which we aim to maximize the lifetime of a sensor network by adding a set of relays to it. The network lifetime is defined as the time until the network becomes disconnected. The Fiedler value, which is the algebraic connectivity ..."
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Cited by 6 (1 self)
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Abstract—In this paper we address the network maintenance problem, in which we aim to maximize the lifetime of a sensor network by adding a set of relays to it. The network lifetime is defined as the time until the network becomes disconnected. The Fiedler value, which is the algebraic connectivity of a graph, is used as an indicator of the network health. The network maintenance problem is formulated as a semidefinite programming (SDP) optimization problem that can be solved efficiently in polynomial time. First, we propose a network maintenance algorithm that obtains the SDPbased locations for a given set of relays. Second we propose a routing algorithm, namely, Weighted Minimum Power Routing (WMPR) algorithm, that significantly increases the network lifetime due to the efficient utilization of the deployed relays. Third, we propose an adaptive network maintenance algorithm that relocates the deployed relays based on the network health indicator. Further, we study the effect of two different transmission scenarios, with and without interference, on the network maintenance algorithm. Finally, we consider the network repair problem, in which we find the minimum number of relays along with their SDPbased locations to reconnect a disconnected network. We propose an iterative network repair algorithm that utilizes the network maintenance algorithm. Index Terms—Connectivity, power control, routing, semidefinite programming, sensor networks. I.