Cyber-Physical Systems

Cyber-Physical Systems (CPS) are integrations of computation, networking, and physical processes. Embedded computers and networks monitor and control the physical processes, with feedback loops where physical processes affect computations and vice versa. The economic and societal potential of such systems is vastly greater than what has been realized, and major investments are being made worldwide to develop the technology. The technology builds on the older (but still very young) discipline of embedded systems, computers and software embedded in devices whose principle mission is not computation, such as cars, toys, medical devices, and scientifi c instruments. CPS integrates the dynamics of the physical processes with those of the software and networking, providing abstractions and modeling, design, and analysis techniques for the integrated whole.

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Click on icons above for details. Please send comments, suggestions, and links to Alternatively, you can download and run the above model in Ptolemy II. Just point Vergil (the Ptolemy II visual editor) to

As a discipline, CPS is an engineering discipline, focused on technology, with a strong foundation in mathematical abstractions. The key technical challenge is to conjoin abstractions that have evolved over centuries for modeling physical processes (differential equations, stochastic processes, etc.) with abstractions that have evolved over decades in computer science (algorithms and programs, which provide a "procedural epistemology" [Abelson and Sussman]). The former abstractions focus on dynamics (evolution of system state over time), whereas the latter focus on processes of transforming data. Computer science, as rooted in the Turing-Church notion of computability, abstracts away core physical properties, particularly the passage of time, that are required to include the dynamics of the physical world in the domain of discourse.

Online talks about CPS

Berkeley CPS Activities

At Berkeley, CHESS is pursuing foundational research in the abstractions and analytical techniques of CPS. Some of the projects addressing this problem:

Some specific research products relevant to CPS:

Berkeley CPS Publications

CPS publications from CHESS include:

  1. J. Eidson, E. A. Lee, S. Matic, S. A. Seshia, J. Zou. Distributed Real-Time Software for Cyber-Physical Systems, Proceedings of the IEEE (special issue on CPS), 100(1):45-59, January 2012.
  2. P. Derler, E. A. Lee, A. Sangiovanni-Vincentelli. Modeling Cyber-Physical Systems, Proceedings of the IEEE (special issue on CPS), 100(1):13-28, January 2012.
  3. S. Tripakis, C. Stergiou, C. Shaver and E. A. Lee, A Modular Formal Semantics for Ptolemy. To appear in Mathematical Structures in Computer Science Journal.
  4. E. A. Lee and S. A. Seshia, Introduction to Embedded Systems, A Cyber-Physical Systems Approach,, ISBN 978-0-557-70857-4, 2011.
  5. E. A. Lee, CPS Foundations in Proc. Design Automation Conference (DAC), ACM, 2010.
  6. E. A. Lee, Disciplined Heterogeneous Modeling, in D.C. Petriu, N. Rouquette, O. Haugen (Eds.): MODELS 2010, PRT II, LNCS 6395, Springer-Verlag, pp. 273-287, Proceedings of the ACM/IEEE 13th International Conference on Model Driven Engineering, Languages, and Systems (MODELS), Oct. 3-8, 2010.
  7. S. A. Edwards, S. Kim, E. A. Lee, I. Liu, H. D. Patel, M. Schoeberl. A Disruptive Computer Design Idea: Architectures with Repeatable Timing, Proceedings of International Conference on Computer Design (ICCD), IEEE, Lake Tahoe, CA, 4-7, pp. 54-59, October, 2009.
  8. E. A. Lee, S. Matic, S. A. Seshia, J. Zou. The Case for Timing-Centric Distributed Software. IEEE International Conference on Distributed Computing Systems Workshops: Workshop on Cyber-Physical Systems, IEEE, pp. 57-64, June, 2009.
  9. E. A. Lee, Computing Needs Time, Communications of the ACM, Vol. 52, Issue 5, May 2009. Earlier version , EECS Department, University of California, Berkeley, Technical Report No. UCB/EECS-2009-30, February 18, 2009.
  10. A. Goderis, C. Brooks, I. Altintas, E. A. Lee, C. Gobel. Heterogeneous Composition of Models of Computation, Future Generation Computer Systems (FGCS), 25(5):552-560, May 2009.
  11. X. Liu, E.A. Lee, "CPO semantics of timed interactive actor networks," Theoretical Computer Science 409 (1): pp.110-25, 2008. Earlier version.
  12. C. Brooks, C. Cheng, T. H. Feng, E. A. Lee and R. von Hanxleden, "Model Engineering using Multimodeling," 1st International Workshop on Model Co-Evolution and Consistency Management (MCCM '08), September 30, 2008.
  13. E. A. Lee, "Time is a Resource, and Other Stories," International Symposium on Object/Component/Service-Oriented Real-Time Distributed Computing (ISORC), May, 2008; Position statement for panel: "Wrong Assumptions and Neglected Areas in Embedded Research."
  14. E. A. Lee, "Cyber Physical Systems: Design Challenges," International Symposium on Object/Component/Service-Oriented Real-Time Distributed Computing (ISORC), May, 2008; Invited Paper.
  15. Published in Object Oriented Real-Time Distributed Computing (ISORC), 2008 11th IEEE International Symposium on 5-7 May, 2008, pp. 363-369, DOI 10.1109/ISORC.2008.1, Orlando, FL.
  16. E. A. Lee, H. Zheng, "Leveraging Synchronous Language Principles for Heterogeneous Modeling and Design of Embedded Systems," EMSOFT, September 30, October 3, 2007, Salzburg, Austria.
  17. S. A. Edwards, E. A. Lee, "The Case for the Precision Timed (PRET) Machine," DAC 2007, June 4-8, 2007, San Diego, California.
  18. E. A. Lee. "Cyber-Physical Systems - Are Computing Foundations Adequate?," Position Paper for NSF Workshop on Cyber-Physical Systems: Research Motivation, Techniques and Roadmap, Austin, Texas, October 16-17, 2006.
  19. E. A. Lee. "Concurrent Semantics without the Notions of State or State Transitions," in Proceedings of the International Conference on Formal Modelling and Analysis of Timed Systems (FORMATS), Paris, (LNCS 4202, Springer-Verlag, E. Asarin and P. Bouyer, Eds.), September 25-27, 2006.
  20. X. Liu, E. Matsikoudis, and E. A. Lee. "Modeling Timed Concurrent Systems," in Proceedings of the 17th International Conference on Concurrency Theory (CONCUR), Bonn, Germany, August 27-30, C. Baier and H. Hermanns (Eds.), LNCS 4137, Springer-Verlag, pp. 1-15, 2006.
  21. E. A. Lee. "The Problem with Threads," in IEEE Computer, 39(5):33-42, May 2006.
  22. E. A. Lee, "Building Unreliable Systems out of Reliable Components: The Real Time Story", Technical Report No. EECS-2005-5, EECS Department, University of California, Berkeley, October 2005.
  23. E. A. Lee, "Absolutely Positively On Time: What Would It Take?," Editorial, Draft version: May 18, 2005.
    Published in: Embedded Systems Column, IEEE Computer, July 2005, 38, pp.85-87.
  24. E. A. Lee, "Engineering Education: A Focus on Systems," in Advances in Control, Communication Networks, and Transportation Systems: In Honor of Pravin Varaiya, E.H. Abed (Ed.), Systems and Control: Foundations and Applications Series, Birkhauser, Boston, 2005, pp. 69-78.
  25. E. A. Lee and H. Zheng, "Operational Semantics of Hybrid Systems," Invited paper in Proceedings of Hybrid Systems: Computation and Control (HSCC) LNCS 3414, Zurich, Switzerland, March 9-11, 2005, pp.25-53.