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Ptolemy Project Vision

Ptolemy Project Vision. Edward A. Lee Robert S. Pepper Distinguished Professor Eighth Biennial Ptolemy Miniconference April 16, 2009 Berkeley, CA, USA. Cyber-Physical Systems (CPS) Where it is going. CPS: Orchestrating networked computational resources with physical systems.

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Ptolemy Project Vision

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  1. Ptolemy Project Vision Edward A. Lee Robert S. Pepper Distinguished Professor Eighth Biennial Ptolemy Miniconference April 16, 2009 Berkeley, CA, USA

  2. Cyber-Physical Systems (CPS)Where it is going CPS: Orchestrating networked computational resources with physical systems.

  3. Computer Science: Carefully abstracts the physical world System Theory: Deals directly with physical quantities Cyber Physical Systems: Computational + Physical CPS is Multidisciplinary

  4. Ptolemy Project Research • Foundations: Timed computational semantics. • Bottom up: Embedded processors (PRET). • Top down: Distributed real-time systems (PTIDES). • Holistic: Scalable model-based design.

  5. The established: Object-oriented: class name What flows through an object is sequential control data methods call return The alternative: Actor oriented: actor name What flows through an object is evolving data data (state) parameters ports Output data Input data Object Oriented vs. Actor OrientedSoftware Components Things happen to objects Actors make things happen

  6. Timed Software Semantics super-dense time concurrent actor-oriented models abstraction s S N Causal systems operating on signals are usually naturally (Scott) continuous. fixed-point semantics

  7. Results Software: Ptolemy II realizes a number of timed concurrent models of computation (MoCs) with well-founded rigorous semantics. Ph.D. Theses: [1] Haiyang Zheng, "Operational Semantics of Hybrid Systems," May 18, 2007. [2] Ye Zhou, "Interface Theories for Causality Analysis in Actor Networks," May 15, 2007. [3] Xiaojun Liu, "Semantic Foundation of the Tagged Signal Model," December 20, 2005. Papers: [1] Lee and Matsikoudis, "The Semantics of Dataflow with Firing," in From Semantics to Computer Science: Essays in memory of Gilles Kahn, Cambridge 2009. [2] Ye Zhou and Edward A. Lee. "Causality Interfaces for Actor Networks," ACM Trans. on Embedded Computing Systems, April 2008. [3] Liu and Lee, "CPO Semantics of Timed Interactive Actor Networks,” Theoretical Computer Science 409 (1): pp.110-25, 2008.. [4] Lee, " Application of Partial Orders to Timed Concurrent Systems," article in Partial order techniques for the analysis and synthesis of hybrid and embedded systems, in CDC 07. [5] Lee and Zheng, "Leveraging Synchronous Language Principles for Heterogeneous Modeling and Design of Embedded Systems," EMSOFT ’07. [6] Liu, Matsikoudis, and Lee. "Modeling Timed Concurrent Systems," CONCUR ’06. [7] Cataldo, Lee, Liu, Matsikoudis and Zheng "A Constructive Fixed-Point Theorem and the Feedback Semantics of Timed Systems," WODES'06 etc. ...

  8. Director from an extensible library defines component interaction semantics or “model of computation.” Extensile, behaviorally-polymorphic component library. Type system for transported data Visual editor supporting an abstract syntax Ptolemy II: Our Laboratory for Actor-Oriented Models of Computation Concurrency management supporting dynamic model structure.

  9. Ptolemy Project Research • Foundations: Timed computational semantics. • Bottom up: Embedded processors (PRET). • Top down: Distributed real-time systems (PTIDES). • Holistic: Scalable model-based design.

  10. Bottom Up: Embedded Processors Precision-Timed (PRET) Machines Make temporal behavior as important as logical function. Timing precision with performance: Challenges: • Memory hierarchy (scratchpads?) • Deep pipelines (interleaving?) • ISAs with timing (deadline instructions?) • Multicore (dedicated I/O & real-time processors?) • Predictable memory management (Metronome?) • Languages with timing (discrete events? Giotto?) • Predictable concurrency (synchronous languages?) • Composable timed components (actor-oriented?) • Precision networks (TTA? Time synchronization?) See S. Edwards and E. A. Lee, "The Case for the Precision Timed (PRET) Machine," in the Wild and Crazy Ideas Track of the Design Automation Conference (DAC), June 2007.

  11. PRET Project (Berkeley, Columbia) Funding from NSF, Toyota, National Instruments, plus cooperation with Xilinx, Synfora, and Tidorum Staffing: • Edward A. Lee (UCB PI) • Stephen Edwards (Columbia co-PI) • Jan Rabaey (UCB co-PI) • John Wawrzynek (UCB co-PI) • Christopher Brooks (Technical staff) • Hiren Patel (postdoc) • Hugo Andrade (NI VIF) • Shanna-Shaye Forbes (UCB grad student) • Sunjun Kim (Columbia grad student) • Ben Lickly (UCB grad student) • Isaac Liu (UCB grad student)

  12. Ptolemy Project Research • Foundations: Timed computational semantics. • Bottom up: Embedded processors (PRET). • Top down: Distributed real-time systems (PTIDES). • Holistic: Scalable model-based design.

  13. PTIDES: Programming Temporally Integrated Distributed Embedded Systems Distributed execution under DE semantics, with “model time” and “real time” bound at sensors and actuators. Output time stamps are ≤ real time Input time stamps are ≥ real time Input time stamps are ≥ real time Output time stamps are ≤ real time

  14. PTIDES Project Funding from NSF, Agilent, IBM, Toyota, and the State of California MICRO program, in cooperation with the University of Salzburg, Austria. Staffing: • Edward A. Lee (UCB PI) • Christopher Brooks (Technical staff) • Patricia Derler (Univ. Salzburg grad student) • Slobodan Matic (postdoc) • Thomas Feng (UCB grad student) • Ben Lickly (UCB grad student) • Stefan Resmerita (Univ. Salzburg technical staff) • Yang Zhao (UCB grad student, Google technical staff) • Jia Zou (UCB grad student)

  15. Ptolemy Project Research • Foundations: Timed computational semantics. • Bottom up: Embedded processors (PRET). • Top down: Distributed real-time systems (PTIDES). • Holistic: Scalable model-based design.

  16. Hierarchical MultimodelingHierarchical compositionsof models of computation. Maintaining temporal semantics across MoCs is a main challenge.

  17. Multi-View Modeling:Distinct and separate models of the same system are constructed to model different aspects of the system. Functional model in Statecharts Verification model in SMV Deployment model in Ptolemy II Functional model in Ptolemy II This example is a test case for a collaborative project with Lockheed-Martin Reliability model in Excel

  18. “Model Engineering” Project Funding from AFRL, Army Research Office, Air Force Research Office, Bosch, Lockheed-Martin, and Thales. Staffing: • Edward A. Lee (UCB PI) • Christopher Brooks (Technical staff) • Chihong (Partrick) Cheng (TU Munich) • Thomas Huining Feng (UCB grad student) • Jackie Mankit Leung (UCB grad student) • Eleftherios Matisikoudis (UCB grad student) • Stavros Tripakis (Visiting Research Scientist)

  19. Addressing the Design Challenges for Cyber Physical Systems • Foundations: Timed computational semantics. • Abstract semantics on super-dense time • Bottom up: Make timing repeatable. • Precision-timed (PRET) machines • Top down: Timed, concurrent components. • Distributed real-time discrete-events (PTIDES) • Holistic: Model engineering. • Mulimodeling, ontologies, property system, …

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