1. Institute for Software Integrated Systems Vanderbilt University CYBER PHYSICAL SYSTEMS (CPS) Janos Sztipanovits ISIS, Vanderbilt University

2. 2 Overview  What are Cyber-Physical Systems?  Scientific challenges  Composition and compositionality  How to build, compose networked CPS at all scales?  How to achieve compositionality in high-confidence, dynamically-configured systems?  Design and design automation  What is the meaning and cost of heterogeneity?  How to accommodate changes in products, design process and design culture  Interaction-based computing  What are the new computing paradigms?  How to model interactions

3. 3 CPS: Computing Perspective Two types of computing systems –Desktops, servers, PCs, and notebooks –Embedded The next frontier –Mainframe computing (60’s-70’s) Large computers to execute big data processing applications –Desktop computing & Internet (80’s- 90’s) One computer at every desk to do business/personal activities –Embedded computing (21 st Century) “Invisible” part of the environment Transformation of industry Number of microprocessor units per year –Millions in desktops –Billions in embedded processors Applications: –Automotive Systems Light and heavy automobiles, trucks, buses –Aerospace Systems Airplanes, space systems –Consumer electronics Mobile phones, office electronics, digital appliances –Health/Medical Equipment Patient monitoring, MRI, infusion pumps, artificial organs –Industrial Automation Supervisory Control and Data Acquisition (SCADA) systems for chemical and power plants Manufacturing systems –Defense Source of superiority in all weapon systems

4. CPS: Systems Perspective

5. CPS Definition A CPS is a system in which:  information processing and physical processes are so tightly integrated that it is not possible to identify whether behaviors are the result of computations, physical laws, or both working together  where functionality and salient system characteristics are emerging through the interaction of physical and computational objects

6. 6 Transformation of Industries: Automotive  Current picture  Largely single-vehicle focus  Integrating safety and fuel economy (full hybrids, regenerative braking, adaptive transmission control, stability control)  Safety and convenience “add-ons” (collision avoidance radar, complex airbag systems, GPS, …)  Cost of recalls, liability; growing safety culture  Better future?  Multi-vehicle high-capacity cooperative control roadway technologies  Vehicular networks  Energy-absorbing “smart materials” for collision protection (cooperative crush zones?)  Alternative fuel technologies, “smart skin” integrated photovoltaics and energy scavaging, ….  Integrated operation of drivetrain, smart tires, active aerodynamic surfaces, …  Safety, security, privacy certification; regulatory enforcement  Time-to-market race Image thanks to Sushil Birla, GMC

7. 7  National Health Information Network, Electronic Patient Record initiative  Medical records at any point of service  Hospital, OR, ICU, …, EMT?  Home care: monitoring and control  Pulse oximeters (oxygen saturation), blood glucose monitors, infusion pumps (insulin), accelerometers (falling, immobility), wearable networks (gait analysis), …  Operating Room of the Future (Goldman)  Closed loop monitoring and control; multiple treatment stations, plug and play devices; robotic microsurgery (remotely guided?)  System coordination challenge  Progress in bioinformatics: gene, protein expression; systems biology; disease dynamics, control mechanisms Images thanks to Dr. Julian Goldman, Dr. Fred Pearce Transformation of Industries: Health Care and Medicine

8. 8  Current picture:  Equipment protection devices trip locally, reactively  Cascading failure: August (US/Canada) and October (Europe), 2003  Better future?  Real-time cooperative control of protection devices  Or -- self-healing -- (re-)aggregate islands of stable bulk power (protection, market motives)  Ubiquitous green technologies  Issue: standard operational control concerns exhibit wide-area characteristics (bulk power stability and quality, flow control, fault isolation)  Context: market (timing?) behavior, power routing transactions, regulation IT Layer Images thanks to William H. Sanders, Bruce Krogh, and Marija Ilic Transformation of Industries: Electric Power Grid

9. 9 package org.apache.tomcat.session; import org.apache.tomcat.core.*; import org.apache.tomcat.util.StringManager; import java.io.*; import java.net.*; import java.util.*; import javax.servlet.*; import javax.servlet.http.*; /** * Core implementation of a server session * * @author James Duncan Davidson [duncan@eng.sun.com] * @author James Todd [gonzo@eng.sun.com] */ public class ServerSession { private StringManager sm = StringManager.getManager("org.apache.tomcat.session"); private Hashtable values = new Hashtable(); private Hashtable appSessions = new Hashtable(); private String id; private long creationTime = System.currentTimeMillis();; private long thisAccessTime = creationTime; private long lastAccessed = creationTime; private int inactiveInterval = -1; ServerSession(String id) { this.id = id; } public String getId() { return id; } public long getCreationTime() { return creationTime; } public long getLastAccessedTime() { return lastAccessed; } public ApplicationSession getApplicationSession(Context context, boolean create) { ApplicationSession appSession = (ApplicationSession)appSessions.get(context); if (appSession == null && create) { // XXX // sync to ensure valid? appSession = new ApplicationSession(id, this, context); appSessions.put(context, appSession); } // XXX // make sure that we haven't gone over the end of our // inactive interval -- if so, invalidate and create // a new appSession return appSession; } void removeApplicationSession(Context context) { appSessions.remove(context); } /** * Called by context when request comes in so that accesses and * inactivities can be dealt with accordingly. */ void accessed() { // set last accessed to thisAccessTime as it will be left over // from the previous access lastAccessed = thisAccessTime; thisAccessTime = System.currentTimeMillis(); } void validate() SoftwareControl Crosses Interdisciplinary Boundaries Why is CPS Hard? Disciplinary boundaries need to be realigned New fundamentals need to be created New technologies and tools need to be developed Education need to be restructured

10. Long-Term Goal  Transform how we interact with the physical world just like the internet transformed how we interact with one another.  Transcend space  Control the physical environment remotely  Building CPSs that integrate computational and physical objects requires new systems science foundations.  Fusion of physical and computational sciences Produce significant impact on society and national competitiveness.

11. 11 Overview  What are Cyber-Physical Systems?  Scientific challenges  Composition and compositionality  How to build, compose networked CPS at all scales?  How to achieve compositionality in high-confidence, dynamically-configured systems?  Design and design automation  What is the meaning and cost of heterogeneity?  How to accommodate changes in products, design process and design culture  Interaction-based computing  What are the new computing paradigms?  How to model interactions

12. Example: CPS Composition Theories 1/3 R/r is the pole of the transfer function v(z)/e(z) => the step response may become unstable. v(t) = R * i(t) v(t) = R * i(t -  t) Source: Roitman and Diniz, ICDS’95, 1995

13. Discretization of components using trapezodial rule for integration. Composition task: Not realizable implementation.. Source: Bilbao and Smith III, 2005 Example: CPS Composition Theories 2/3

14.  Wave Digital Filters Alfred Fettweis in the early 1970s, was an attempt at translating analog filters into the digital realm with a pointed emphasis on preserving as much of the underlying physics as possible. Properties: –if the reference filter is passive, the WDF implementation is also passive –guaranteed stability –reduced accuracy requirements for coefficients and good dynamic range –free of zero input limit-cycle oscillation, …  Resonator-Bank Filters Peceli and others, 1980’s. Similar properties, different implementation strategy. Need for investigating composition theories for CPS Example: CPS Composition Theories 3/3

15. 15 Overview  What are Cyber-Physical Systems?  Economic context  Scientific challenges  Composition and compositionality  How to build, compose networked CPS at all scales?  How to achieve compositionality in high-confidence, dynamically-configured systems?  Design and design automation  What is the impact and cost of heterogeneity?  How to accommodate changes in products, design process and design culture  Interaction-based computing  What are the new computing paradigms?  How to model interactions

16. Heterogeneity and Modeling Languages Computing System Composition Domain Physical System Composition Domain Physical instantiation Logical specification (source code) Physical system characteristics Physical Models Modeling Languages – Structure – Behaviors Physical Laws – Physical variables – Physical Units “Cyber” Models Modeling Languages – Structure – Behaviors Mathematical Domains – traces/state variables – no reference semantics or “semantic units”

17. Challenges in DSML Semantics DSML Usually, specification stops at the level of abstract syntax metamodels (“static semantics”) Specification of behavioral semantics (if done) – involve major effort due to overly complex modeling languages, – use a wide range of formalisms and Impact is far-reaching – tool chains are closed and built around loosely defined “conventions” and proprietary interpretations of semantics instead of standards – potential semantic mismatches create unacceptable risk for safety critical applications Major roadblock that slows down acceptance of model-based design technology. Semantic Domain ? Need for developing theories and tools for compositional specification of DSML semantics

18. Modeling Controller Synthesis System Analysis Code Synthesis Validation Verification Target Analysis Platform Simulink Stateflow ECSL/GME Ptolemy Matlab Simulator Checkmate SAL Teja UP Reach Charon R-T Workshop ECSL/GME Kestrel Ptolemy Checkmate Charon WindView AIRES Checkmate AIRES MPC555/ OSEK PENTIUM/ QNX Platform Models Plant Model Integrated Model Design Feedback Valid Model Code/Model Test Vectors Valid Code/Model Design Feedback Download Valid Model BACKPLANE Open Tool Integration Framework Metamodeling Metamodel Composition & Validation Metagenerators UML/OCL GME/Meta MIC/GEN Kestrel Comp/Platf Modeling Component Implement. System Modeling Component Integration Validation Verification Target Analysis Platform UML/Rose ESML/GME Manual ESML/GME Honeywell CMU ESML/GME Honeywell TimeWeaver AIRES SWRI/ASC TimeWiz AIRES SWRI/ASC ESML/GME PENTIUM/ TAO/ BOLD- STROKE Platform Models Partial Model System Model Design Feedback Component Code Interaction/Fault mgmt/… Models Valid Code/Model Design Feedback Download Integrated Code Model Component Model Design Feedback Integrated Physical/Computational Modeling and Analysis Generative Programming Hybrid System Analysis Customizable (metaprogrammable) modeling tools and generators Open tool integration framework; configurable design flow and composable design environments Automotive Design Flow Avionics Design Flow Goal: Heterogeneous and Composable Design Flows

19. 19 Overview  What are Cyber-Physical Systems?  Economic context  Scientific challenges  Composition and compositionality  How to build, compose networked CPS at all scales?  How to achieve compositionality in high-confidence, dynamically-configured systems?  Design and design automation  What is the meaning and cost of heterogeneity?  How to accommodate changes in products, design process and design culture?  Interaction-based computing  What are the new computing paradigms?  How to model interactions?

20. Change in Computing Platforms Future Computers on Silicon 1 Power Processor Element (PPE) 8 Synergistic Processor Element (SPE) Interconnection (EIB) consists of 4 x 16 byte rings run at half the CPU clock speed and can allow up to 3 simultaneous transfers. Theoretical peak of the EIB is 204.8 Gigabytes per second. Programming challenge – coordinating the execution of jobs…. Programming models: - job queue, - multitasking, - stream processing, - … Challenge: understanding task interaction and utilizing concurrency

21. Change in CPS Applications: Networked Systems COP Distributed Database Information Layer Interoperable export WIN-T UE/HQ ESO Standards-Based Open Software Architecture L COP Common Operating Picture HQ ESO EPLRS SINCGARS VHF Link 4A Link 11 Link 16 WIN T Hierarchical Ad-Hoc Network Data Images Voice Video Mission Planning & Prep Situation Understanding Battle Mgmt & Execution Sensor Fusion Target Recognition Integrated Sustainment Embedded Training Common Services Information Management Computing and Networking Warfighter Interface Vetronics Common Vehicle Subsystems HQ Battle Command EO/IR SAR/MTI UGS WNW Reachback HHQ WNW Joint Common Database XX stubnet DB Synchronization Information Management Platform Networked Command Interoperability FIOP JTRS Future Systems in the Field Heterogeneous CPS Open Dynamic Architecture - heterogeneous networking - heterogeneous components Very high level concurrency with complex interactions Challenge: understanding system interactions and analyzing (bounding) behavior

22. Interaction and Coordination  Rich time models instead of sequencing  Behavioral invariants instead of end results  Functionality through interactions of ongoing behaviors instead of sequence of actions  Component architectures instead of procedural abstraction  Concurrency models with partially ordered instead of linearly ordered event sets  Precise interaction and coordination protocols  Hugely increased system size with controllable, stable behavior  Dynamic system architectures (nature and extent of interaction can be modified)  Adaptive, autonomic behavior  Self-descriptive, self monitoring system architecture for safety guarantees. Changes in Cyber Changes in Physical

23. Summary  CPS-s represent the coming new age in systems design  The required technology changes are fundamental – go way beyond “multidisciplinary” design  The impact on competitiveness is huge: CPS-s are the foundation for the systems industry