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Interplay Between Delays, Network Graphs, and Stability/Performance in Coupled Dynamical Systems
Rifat Sipahi

Speaker: Dr. Rifat Sipahi, Northeastern University

Thursday, Nov. 20, 2014  |  2:00 PM CST


We consider a network of agents with certain dynamics, where agents make decisions based on the information they collect from other agents, in order to achieve a common goal. Information received from each agent is however not instantaneous, but time delayed. Successful operation of such a network not only depends on the amount of delays, and types of control laws utilized by the agents, but it also depends on the particular network structure formed by the agents. That is, delays and graph properties of the network arising from agent-to-agent interactions together contribute to the evolution dynamics of the agents.
To capture the fundamentals of this delay-network interplay problem, a particular class of linear time invariant systems is taken into consideration, and various features of such systems are proven; specifically uncovering the links between the finite number of eigenvalues of the arising network graph Laplacian, and the infinitely many eigenvalues associated with the dynamics of the agents as well as with delays. The arising control laws are then adapted to, and implemented on a three-mobile-robot experimental system for a rendezvous problem, using input-output linearization and studying uncertainties. The developed theory is used to design couplings between the robots to render various dynamic behaviors of the robots while achieving rendezvous.
Rifat Sipahi is an Associate Professor at Northeastern University (NEU), Boston, USA (BSc in 2000 (Istanbul Technical University Turkey); MSc in 2002 & PhD in 2005 (University of Connecticut USA); postdoc in 2005-2006 at HeuDiaSyC CNRS at Universite de Technologie de Compiegne, France; 2006-2012: Assistant Professor at Northeastern University). One of Dr. Sipahi’s research topics is on the stability analysis and control of LTI systems with single and multiple delays.
Dr. Sipahi is one of the recipients of 2011 DARPA Young Faulty Award and 2005 Chateaubriand Postdoctoral Scholarship of the French Government. He is one of the authors with S.-I. Niculescu, C.T Abdallah, W. Michiels, and K. Gu on the article “Stability and Stabilization of Systems with Time Delay, Limitations and Opportunities,” published in IEEE Control Systems Magazine in 2011. Prof. Sipahi is a Fellow of ASME, and a member of IEEE. In 2014, he was honored as a Faculty Fellow by NEU College of Engineering. He has served as associate editor, (co-)chair, program committee member in conferences supported by ASME, IEEE, and IFAC, and he is currently the news content editor of the ASME Dynamic Systems and Control Magazine. Prof. Sipahi was the Program Editor and co-organizer of 2012 IFAC Workshop on Time Delays Systems.