Systems Theory and Automatic Control

Systems and Control Seminar in the Winter Semester 2017/18


Fault tolerant clock synchronization over unreliable channels in wireless sensor networks.


Hideaki Ishii
Associate Professor in the Department of Computer Science, Tokyo Institute of Technology.

Time and Place

The seminar talk takes place on November 23, 2017 at 3.00 p.m. in building 09, room 211 at Universitätsplatz 2.


In this talk, we discuss the problem of clock synchronization in wireless sensor networks based on a distributed approach by employing consensus-type algorithms. The sensor nodes face two types of uncertainties. One is that some of the nodes in the network can be faulty and transmit arbitrary signals by not following the given protocol; similar effects may be caused by false data injection by an external malicious attacker. The other is that the communication is unreliable and the packets exchanged may become lost. To deal with these uncertainties, we propose a resilient consensus-type algorithm based on the so-called mean subsequence reduced (MSR) technique where each normal node ignores the outliers in the clock data collected from its neighbors and also makes updates using data from the past if new data has not arrived yet. We establish network connectivity conditions in terms of graph robustness for the MSR algorithm to attain resilient properties.

Information about the Speaker

Hideaki Ishii received the M.Eng. degree in applied systems science from Kyoto University in 1998, and the Ph.D. degree in electrical and computer engineering from the University of Toronto in 2002. He was a Postdoctoral Research Associate with the Coordinated Science Laboratory at the University of Illinois at Urbana-Champaign from 2001 to 2004, and a Research Associate with the Department of Information Physics and Computing, The University of Tokyo from 2004 to 2007. Currently, he is an Associate Professor in the Department of Computer Science, Tokyo Institute of Technology. His research interests are in networked control systems, multi-agent systems, hybrid systems, cyber security of power systems, and probabilistic algorithms. Dr. Ishii has served as an Associate Editor for the IEEE Transactions on Control of Network Systems, IEEE Control Systems Letters, and Mathematics of Control, Signals, and Systems and previously for Automatica and the IEEE Transactions on Automatic Control. He is the Chair of the IFAC Coordinating Committee on Systems and Signals and was the Chair of the IFAC Technical Committee on Networked Systems from 2011 to 2017. He received the IEEE Control Systems Magazine Outstanding Paper Award in 2015.

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