Authors: Bauso, Dario; Giarre', Laura; Pesenti, Raffaele

Abstract: In this paper we discuss agents exchanging quantized flows to diverge one from the others according to a dissensus protocol. A Quantized Gossip algorithm is considered. Evolutions of the states during switching intervals and at switching instants and their property are described and analyzed. The modeling of switching systems describing networks where death and duplication processes occur is described. Some properties of the topology reached by the network when different rules of duplication and inheritance are implemented.

Keywords: Consensus problems; Control with communication constraints (quantization effects); Randomized algorithms, gossip algorithms

Identifier: 10.3182/20090924-3-IT-4005.00001

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Simonetto, Andrea; Keviczky, Tamas

Abstract: Particle filters have been widely used for the solution of optimal estimation problems in nonlinear non-Gaussian environments. One of their drawbacks is that these methods are computationally expensive. In the past few years, new developments have been made in trying to distribute the particle filter algorithm among different computing agents in order to make the underlying computations tractable. This period also witnessed the rise of general purpose GPU devices, which are making massive code parallelization possible. These developments have the potential to make the particle filter a viable alternative for real-time implementations in the near future, even when the number of required particles is high. In this paper we review the state-of-the-art in distributed particle filtering and propose a method that is applicable to distributed computing architectures.

Keywords: Decentralized algorithms for computation over sensor networks; Coordinated control and estimation over networks; Consensus problems

Identifier: 10.3182/20090924-3-IT-4005.00024

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Ishido, Yumiko; Takaba, Kiyotsugu

Abstract: This paper is concerned with robust stabilization of an uncertain system over a rate-limited digital channel from the viewpoint of input-output stability. Because of the quantization in the communication channel,it is impossible to apply the traditional small gain theorem to establish robust stability of the feedback system. To overcome this difficulty, we introduce a new notion of small l-p signal l-p stability, and derive a sufficient robust stability condition against l-p gain-bounded uncertainty based on this notion. Furthermore, for the case of p=infinity, a sufficient data rate for the existence of a robustly stabilizing encoder-controller pair is explicitly given.

Keywords: Control with communication constraints (quantization effects etc)

Identifier: 10.3182/20090924-3-IT-4005.00051

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Blanchini, Franco; Krajewski, Wieslaw; Miani, Stefano; Viaro, Umberto

Abstract: This paper is concerned with the control of network data transfer so as to avoid internet traffic congestion. Specifically, a new Active Queue Management (AQM) algorithm supporting the Transmission Control Protocol (TCP) is suggested. To this purpose, the TCP dynamics is described by means of a second--order model with delayed input obtained from the linearization of an efficient nonlinear fluid--based model. By applying the Artstein transformation, the input--delayed model is first reduced to a delay--free model. Then, a feedback AQM controller is designed for this model using a Sliding Mode Control (SMC) strategy. Simulation results show the effectiveness of the proposed AQM technique.

Keywords: Message passing algorithms; Belief propagation

Identifier: 10.3182/20090924-3-IT-4005.00050

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Duan, Houli; Li, Zhiheng; Zhang, Yi; Zhang, Yi; Zhang, Zuo; Teng, Renjie; Yao, Danya

Abstract: Robustness is an important performance index of urban transit networks. The robustness analysis will lead to better evaluation and optimization measures of urban transit systems. In this paper, first, three types of urban transit system models are proposed based on the bipartite graph model, namely the original transit network(OTN), the transit stations network(TSN) and the transit lines network(TLN). Then a robustness index is defined to meet the practical requirement of traffic transit networks. A rapid robustness analysis algorithm based on a shortest path analysis is designed for the robustness analysis of urban transit networks. Finally, the robustness of Beijing transit system under the random attack and intentional attack is analyzed.

Keywords: Graph models for networks; Percolation. Network coding; Coordinated control and estimation over networks

Identifier: 10.3182/20090924-3-IT-4005.00042

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Menon, Prathyush P; Edwards, Christopher

Abstract: In this paper, a novel methodology is proposed for detection of faults in the individual nodes of a network of dynamical systems at a supervisory level. The scheme is based on sliding mode observers and the faults are reconstructed by appropriate processing of the equivalent output error injection signal required to maintain sliding. The proposed fault detection scheme is inherently robust, nonlinear and can accommodate time varying coupling strengths. Stability conditions for the sliding mode observer are derived and depend solely on the dynamics of an individual node of the network.

Keywords: Coordinated control and estimation over networks

Identifier: 10.3182/20090924-3-IT-4005.00026

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Li, Xu-Guang; Cela, Arben; Niculescu, Silviu-Iulian; Reama, Abdellatif

Abstract: This paper studies the stability of networked control systems with a switched control law. Both the cases of constant and time-varying sampling periods are considered and the stability regions are obtained. It is seen that this method can lead to bigger sampling period, guaranteeing the stability, than the standard control law. In particular, some NCSs can be stabilized with an in¯nitely big sampling period. A su±cient condition for this case is presented.

Keywords: Control with communication constraints (quantization effects etc)

Identifier: 10.3182/20090924-3-IT-4005.00061

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Battistelli, Giorgio; Benavoli, Alessio; Chisci, Luigi

Abstract: This paper deals with the problem of estimating the state of a discrete-time linear stochastic dynamical system on the basis of data collected from multiple sensors subject to a limitation on the communication rate from the sensors. More specifically, the attention is devoted to a centralized sensor network and data-driven strategies for deciding when transmitting data from each sensor to the fusion node are considered. Sufficient conditions for the boundedness of the state covariance at the fusion node are given. Further, the possibility of determining a communication strategy with optimal performance in terms of minimum mean square estimation error at the fusion node is investigated.

Keywords: Coordinated control and estimation over networks; Control with communication constraints (quantization effects etc)

Identifier: 10.3182/20090924-3-IT-4005.00062

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Liu, Junqi; Gusrialdi, Azwirman; Obradovic, Dragan; Hirche, Sandra

Abstract: Future Distributed Power Grid (DPG) control systems may strongly benefit from the introduction of a communication network enabling cooperation between distributed generators. However, this typically comes at the cost that network induced time delay deteriorates control performance and possibly destabilizes the overall system. In this paper we study the effect of the time delay on the performance of a DPG with networked cooperative controllers exchanging state information of generators via a communication network and analyze up to which time delay such a communication network is still beneficial for the overall control performance. Here the delay is assumed to be constant and identical for all links. Standard Linear Quadratic Regulators (LQR) are designed together with communication topology, but without explicitly considering the time delay. We compare the Linear Quadratic (LQ) cost in infinite horizon as a measure of the performance of two cases: the networked cooperative controller with global information and time delay vs. the controller with only local information. It is observed that there exists a performance guaranteed time delay bound where the cost with the cooperative controller is smaller than without information exchange, i.e. it is still beneficial to introduce a communication network. By means of a Linear Matrix Inequality (LMI) problem based on first order Pade approximation for time delay this performance guaranteed time delay bound is approximated in a systematic way. A numerical example is given to illustrate the result.

Keywords: Coordinated control and estimation over networks; Control with communication constraints (quantization effects etc)

Identifier: 10.3182/20090924-3-IT-4005.00029

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Miani, Stefano; Morassutti, Aurelio Carlos

Abstract: In this paper, discrete-time networked control systems (NCS) with packet dropouts and bounded-and-known delays in the sensor channel in a worst case setting are considered. Such systems are modeled as time-varying switching systems and analyzed by means of recent results in the area of switching control. By means of these results it is shown that: (a) such systems can be stabilized by a switching observer based controller if and only if a set of linear matrix inequalities (LMIs) are satisfied and (b) the satisfaction of such conditions allows to parameterize any family of stabilizing switching controllers.

Keywords: Control with communication constraints (quantization effects etc); Decentralized algorithms for computation over sensor networks

Identifier: 10.3182/20090924-3-IT-4005.00057

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Huang, Chi; Ho, Daniel W. C.; Lu, Jianquan

Abstract: Many existing papers have studied synchronization of complex dynamical networks provided with certain topology. However, the exact topology of a network is sometimes uncertain, since unavoidable noisy and measurement error are very common in real-world networks. In this paper, synchronization of complex network with structure uncertainty and coupling delay is investigated. The structure uncertainty is respectively discussed as polytopic or norm-bounded representation. In either case, local synchronization criteria for network with uncertain inner or outer coupling matrix are proposed. All the criteria are in terms of linear matrix inequalities (LMIs), which is numerically solvable. Finally, an illustrative example is presented to demonstrate the effectiveness of the proposed results.

Keywords: Graph models for networks; Percolation. Network coding; Consensus problems

Identifier: 10.3182/20090924-3-IT-4005.00016

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Xiong, Wenjun; Ho, Daniel W. C.

Abstract: In this paper, synchronization of a directed network with Markovian jump (DNMJ) and nonlinear perturbations is considered. By analyzing the structure of the network, a pinning control scheme is given to ensure the synchronization of all nodes in a DNMJ. Finally, an example is provided to illustrate the effectiveness of the gained criteria.

Keywords: Multivehicle systems, flocking

Identifier: 10.3182/20090924-3-IT-4005.00004

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: None

Abstract:

Keywords:

Identifier: 10.3182/20090924-3-IT-4005.90002

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Ermon, Stefano

Abstract: The ability to maintain belief relationship among entities in autonomic networks is considered a major challenge. In this work we tackle the problem by casting it into the framework of Estimation Theory as an inference problem on a Markov Random Field. A fully distributed algorithm based on message passing techniques is then proposed, where messages are not considered as abstract intermediate results of a computation, but as real messages exchanged by the nodes in the network. With this case study we therefore demonstrate that Markov Random Field theory used in combination with Message Passing algorithms constitutes a powerful theoretical framework for the development of algorithms for information distribution and fusion.

Keywords: Message passing algorithms; Belief propagation; Coordinated control and estimation over networks

Identifier: 10.3182/20090924-3-IT-4005.00033

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: Goldin, Darina; Attia, Sid Ahmed

Abstract: This contribution addresses the problem of communication topology changes induced by the movement of a set of mobile agents. The network is modeled as a unit disk graph (UDG) where each unit disk is centered in a node and where the communication topology is given by the instantaneous agents position. UDG allows for a compact representation of the communication topology as an intersection of unit disks. Fundamental properties of UDG are then used to characterize the feasible communication topologies. Under certain mobility assumptions, we show that all the transitions between the set of induced graphs are possible provided that the cardinality of the corresponding set of edges are different at most by one element.

Keywords: Graph models for networks; Percolation. Network coding; Multivehicle systems, flocking; Coordinated control and estimation over networks

Identifier: 10.3182/20090924-3-IT-4005.00040

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009

Authors: None

Abstract:

Keywords:

Identifier: 10.3182/20090924-3-IT-4005.90001

Conference: 1st IFAC Workshop on Estimation and Control of Networked Systems

Location: Cultural Center, Don Orione Artigianelli, Italy

Start Date: Thu Sep 24 2009 - End Date: Sat Sep 26 2009