Cooperative optimization is necessary when multiple controllable agents (e.g., nodes of a sensor network) carry out a "mission" with a common objective, often in an uncertain environment. Cooperation requires cross-agent communication which is typically asynchronous, wireless, and subject to limitations imposed by energy constraints and obstacles in the environment. We will discuss a multi-traveling-salesman type of mission where agents must visit (alone or in groups) "target points" with associated "rewards" so as to maximize the total collected reward. We will show how to formulate and solve a receding horizon optimization problem adopting a "hedge-and-react" as opposed to an "estimate-and-plan" approach, thus bypassing the combinatorial and stochastic complexity of explicitly assigning agents to target points. We will also discuss "coverage" missions where agents are tasked with the problem of cooperatively discovering target points. In all such problems, optimization is carried out in distributed fashion with agents asynchronously taking control actions as well as communicating their state to their peers. We address the question: How can we achieve optimization objectives with minimal cross-agent communication and no synchronization? We show that it is possible for agents to communicate infrequently and yet guarantee convergence of such cooperative distributed optimization schemes. The presentation will include interactive software demonstrations and applications to cooperative settings that involve teams of small wireless robots in a laboratory environment.

Biography of Dr. Christos G. Cassandras
E-mail: cgc@bu.edu
URL: http://vita.bu.edu/cgc

Christos G. Cassandras is Professor of Manufacturing Engineering and Professor of Electrical and Computer Engineering at Boston University. He is also co-founder of Boston University's Center for Information and Systems Engineering (CISE). He received degrees from Yale University (B.S., 1977), Stanford University (M.S.E.E., 1978), and Harvard University (S.M., 1979; Ph.D., 1982). In 1982-84 he was with ITP Boston, Inc. where he worked on the design of automated manufacturing systems. In 1984-1996 he was a faculty member at the Department of Electrical and Computer Engineering, University of Massachusetts/Amherst. He specializes in the areas of discrete event and hybrid systems, stochastic optimization, and computer simulation, with applications to computer and sensor networks, manufacturing systems, and transportation systems. He has published over 250 refereed papers in these areas, and four books. He has guest-edited several technical journal issues and serves on several journal Editorial Boards. Dr. Cassandras is currently Editor-in-Chief of the IEEE Transactions on Automatic Control and has served as Editor for Technical Notes and Correspondence and Associate Editor. He has been on the IEEE CSS Board of Governors, chaired the CSS Technical Committee on Control Theory, and served as Chair of several conferences. He has been a plenary speaker at various international conferences, including the American Control Conference in 2001 and the IEEE Conference on Decision and Control in 2002. He is the recipient of several awards, including the Distinguished Member Award of the IEEE Control Systems Society (2006), the 1999 Harold Chestnut Prize (IFAC Best Control Engineering Textbook) for Discrete Event Systems: Modeling and Performance Analysis, and a 1991 Lilly Fellowship. He is a member of Phi Beta Kappa and Tau Beta Pi. He is also a Fellow of the IEEE.