Published: May 3, 2010
Electrical Engineering Professor Wins Richard E. Bellman Control Heritage Award

Dragoslav D. Siljak, the Benjamin and Mae Swig University Professor in the School of Engineering at Santa Clara University, has won the prestigious Richard E. Bellman Control Heritage Award for his fundamental contributions to the theory of large-scale systems, decentralized control, and parametric approach to robust stability.

The award is the highest recognition of professional achievement for U.S. control systems engineers and scientists, given for distinguished career contributions to the theory or application of automatic control. Bestowed by the American Automatic Control Council (AACC), an association of the control systems divisions of eight member societies, the award is named after the mathematician Richard Bellman, who pioneered the field of dynamic programming, which is essential to control system theory.

Siljak joined the SCU faculty in 1964. A prolific scholar, he has published an array of books and papers, including four monographs (Decentralized Control of Complex Systems, Large-Scale Dynamic Systems, Nonlinear Systems, and Control of Complex Systems: Structural Constraints and Uncertainty) and more than 200 papers in scholarly and scientific journals. In 1999, the Institute of Electrical and Electronics Engineers honored him with the prestigious title of Life Fellow.

His analysis of intricate mathematical models provides a glimpse into how the interdependent parts of complex systems interact in complicated and uncertain ways in order to determine optimal strategies for localized, stabilizing control. "Interest in complex systems has grown in both the living and man-made systems. Everything is becoming more complex-the electric power systems, transportation and communication networks. Everywhere you turn, you see these complex systems," Siljak explains. He has analyzed models in areas as diverse as population biology, the arms race, large space structures, competitive equilibrium in mathematical economics, robotics, electric power systems, and gene regulation. "When we study these models, we don't want to know just what the world is, we want to find what the world can become," he says.

Engineering Dean Godfrey Mungal, the Sobrato Professor of Engineering, lauded his colleague's contributions and achievements. "Drago Siljak is an icon in the field of stability and control. Past winners of the award have come mostly from research 1 universities, so it is even more impressive that he has been recognized from an institution which carries a high teaching load," Mungal notes. "In 2007, his book Large-Scale Dynamic Systems, Stability and Structure was reprinted after 30 years as a Dover Classic, again attesting to his impact in the field."

That impact was reiterated earlier this year when Siljak's 1991 book, Decentralized Control of Complex Systems, topped the list of sales in Amazon's Systems and Control Systems category-even though it has been out of print for more than 10 years. A used copy fetched more than $800 in auction.

Siljak will formally accept the award on July 1 in Baltimore, MD, at a plenary session during the American Control Conference, the annual conference of the AACC, which is composed of the control systems divisions of the following eight societies: the American Institute of Aeronautics and Astronautics; the American Institute of Chemical Engineers; the Association of Iron and Steel Engineers; the American Society of Civil Engineers; the American Society of Mechanical Engineers; the Institute of Electrical and Electronics Engineers; the Instrumentation, Systems, and Automation Society; and the Society for Computer Simulation.

New 2010 Book

Control of Complex Systems: Structural Constraints and Uncertainty
Aleksandar I. Zecevic and Dragoslav D. Siljak
Communication and Control Engineering
Springer Verlag, 2010

Back Cover

"Control of Complex Systems: Structural Constraints and Uncertainty" focuses on control design under information structure constraints and uncertainty, with a particular emphasis on large-scale systems. The complexity of such systems poses serious computational challenges and severely restricts the types of feedback laws that can be used in practice. This book systematically addresses the main issues, and provides a number of applications that illustrate potential design methods. Most of these methods utilize Linear Matrix Inequalities, which have become a popular design tool over the past two decades. Authors use their years of experience in the control field to also:

  • Address the issues of large-scale systems as they relate to robust control, dynamic network interconnections, and information structure constraints
  • Discuss a new approach to applying standard LMI techniques to large-scale systems, combining graphic-theoretic decomposition techniques with appropriate low-rank numerical approximations to dramatically reduce the computational effort
  • Provide numerous examples in a wide variety of applications, ranging from electric power systems and nonlinear circuits to platoons of vehicles and large flexible mechanical structures
  • Introduce a series of new theoretical results related to dynamic graphs and Boolean networks. Applications of these results include gene regulation and growth models for large-scale organic structures

"Control of Complex Systems: Structural Constraints and Uncertainty" will appeal to practicing engineers, researchers and students working in control theory, feedback design, and other related areas.

Chapter 1. Decompositions of Large-Scale Systems
Chapter 2. Information Structure Constraints
Chapter 3. Algebraic Constraints on the Gain Matrix
Chapter 4. Regions of Attraction
Chapter 5. Parametric Stability
Chapter 6. Future Directions: Dynamic Graphs
Bibliography (at the end of each chapter)

Dover Publications paperback reprint of the book

North Holland, Amsterdam, 1978

appears in November 2007


International Journal of Robust and Nonlinear Control
Volume 17, Issue No. 5 - 6, 2007, p. 361

Special Issue Dedicated to the 80th Birthday od V. A. Yakubovich

Academician Vladimir A. Yakubovich: A Tribute

Ever since A. I. Lur'e introduced the absolute stability problem of nonlinear automatic control systems in his book in 1951, numerous researchers have proposed solutions and extensions of the problem, thus making it one of the most - researched problems in control theory. In my opinion, there are three crucial contributions that stand above all others. The frequency method introduced by V. M. Popov in 1960, the method of linear matrix inequalities proposed by V. A. Yakubovich in 1962, and Kalman's version of the positive real lemma formulated in 1963 via the concepts of controlability and observability. It has been the concept of matrix inequalities, however, that achieved special significance in a large number of areas in control theory and beyond. Supported by the recent advances in convex optimization, the matrix inequalities methods of Yakubovich have dramatically changed the way we approach problems in control theory and applications.

It is with great respect and pleasure that I offer to professor Yakubovich my best wishes for his health and happiness on the occasion of his 80th birthday.

Dragoslav D. Siljak
Santa Clara University,
Santa Clara, California, U.S.A.

Dynamic Graphs in Modeling of Complex Systems

Drago Siljak

Santa Clara University

Friday, June 1st, 2007 3:00pm-4:00pm ESB 2001


Dynamic graphs are defined in a linear graph space as one-parameter group of transformations of the space into itself. Stability of equilibrium graphs is formulated in the sense of Liapunov to study motions of positive graphs in the nonnegative orthant of the graph space. In transportation and communication problems, the edges of a dynamic graph representing the network can be considered as goods of a multiple market system where economic agents choose the edges with their weights taken as given prices to come up with the shortest paths which minimize cost. The edges are regarded as gross substitute goods and conditions are provided for stability of the resulting competitive equilibrium. When a complex system is represented as an interconnection of dynamic subsystems (agents), a dynamic graph is used by a coordinator to make sure that a desired level of interconnections between the subsystems is preserved as a connectively stable equilibrium. The equilibrium remains stable despite uncertain structural perturbations whereby the coupling between subsystems changes during the time-evolution of the overall system. The coordinator can be used to adaptively adjust the interconnection levels in multi-agent systems in order to assign the prescribed state as a stable equilibrium point of the overall system. The equilibrium assignment is achieved by solving an optimization problem involving a two-time-scale system; the coordinator action is slow compared to the fast dynamics of the agents. Polytopic connective stability of the multi-agent systems is established by applying the concept of vector Liapunov functions and the theory of M-matrices.

About the Speaker:

Drago Siljak received the Ph.D degree in 1963 from the University of Belgrade, Belgrade, Yugoslavia. Since 1964 he has been with Santa Clara University, where he is the B & M Swig University Professor in the School of Engineering and teaches courses in system theory and applications. His research interests are in the theory of large scale systems and its applications to problems in control engineering, power systems, economics, aerospace, and model ecosystems. He is the author of Nonlinear Systems (Wiley, 1969), Large-Scale Dynamic Systems (North Holland, 1978), and Decentralized Control of Complex Systems (Academic Press, 1991). He is an honorary member of the Serbian Academy of Sciences and Arts and is a Life Fellow of IEEE.


The 1991 book Decentralized Control of Complex Systems, which was published by Academic Press (Mathematics in Science and Engineering), was ranked #1 on Amazon Books in the two categories, Systems and Control Systems, and #23 in the Information Theory category. The book has been out of print for more than ten years, and the price of a used copy of the book reached $800.