Institute for Software Integrated Systems Vanderbilt University MODEL-INTEGRATION AND CYBER PHYSICAL SYSTEMS: A SEMANTICS PERSPECTIVE Janos Sztipanovits with Ted Bapty , Gabor Karsai and Sandeep Neema Institute for Software Integrated Systems Vanderbilt University Email: [email protected] FM 2011 Limerick, Ireland 22 June 2011 About the Topic CPS is a rapidly emerging, cross-disciplinary field with well -understood and urgent need for formal methods driven by challenges in model-based design system verification and manufacturing Overview Cyber-Physical Systems (CPS) CPS and Domain Specific Modeling Languages Model Integration Challenge Formal Semantics of DSMLs Structural Semantics Behavioral Semantics Practical Use of Formal Semantics Addressing Horizontal Heterogeneity Addressing Vertical Heterogeneity Summary Overview Cyber-Physical Systems (CPS) CPS and Domain Specific Modeling Languages Model Integration Challenge Formal Semantics of DSMLs Structural Semantics Behavioral Semantics Practical Use of Formal Semantics Addressing Horizontal Heterogeneity Addressing Vertical Heterogeneity Summary CPS is About Engineered Systems Boston Dynamics: BigDog Energy Internet: When IT Meets ET Known Drivers of CPS Networking and Information Technology (NIT) hbihave been increasi ildngly used as uniliversal system integrator in human – scale and societal – scale systems Functionality and salient system characteristics emerge through the interaction of networked physical and computational objects Engineered products turn into Cyber-Physical Systems (CPS): networked interaction of physical and computational processes The Good News… Networking and computing delivers precision and flexibility in interaction and coordination Computing/Communication Integrated CPS Rich time models Elaborate coordination of physical processes Precise interactions across Hugely increased system size highly extended with controllable, stable spatial/temporal dimension behavior Flexible, dynamic DidtiDynamic, adaptive communication mechanisms architectures Precise time-variant, nonlinear Adaptive, autonomic systems behavior Introspection, learning, Self monitoring, self-healing reasoning system architectures and better safety/security guarantees. …and the Challenges Fusing networking and computing with physical processes brings new unsolved problems Computing/Communication Integrated CPS Cyber vulnerability Physical behavior of systems can be manipulated New type of interactions Lack of composition theories across highly extended for heterogeneous systems: spatial/temporal dimension much unsolved problems Flexible, dynamic VtliVastly increased compl litexity communication mechanisms and emergent behaviors Precise time-variant, nonlinear Lack of theoretical behavior foundations for CPS dynamics Introspection, learning, Verification, certification, reasoning ppyredictability has fundamentally new challenges. Foundation for Convergence: Model-Based Design Communication Software Control Systems 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 [[email protected]] * @author James Todd [[email protected]] */ 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() Modeling Layer • StSystems EiEngineer ing: Opera tion researc h, Re lia bility, Requ iremen t spec.,.. • Control Engineering: Foundation of system theory: Linear, Nonlinear, … • Software Engineering: Formal methods, Model-based SE, RT software, .. • Communication Engineering: Information theory, Layered protocols, … (Re)-convergence of Systems, Control, Software, Communication Engineering 9 Overview Cyber-Physical Systems (CPS) CPS and Domain Specific Modeling Languages Model Integration Challenge Formal Semantics of DSMLs Structural Semantics Behavioral Semantics Practical Use of Formal Semantics Addressing Horizontal Heterogeneity Addressing Vertical Heterogeneity Summary Components of a CPS Battery Components Engine ISG Transmission VMS span: • Multiple Servos physics /Linkages • Multiple domains • MltilMultiple tools Physical Cyber Cyber-Physical Functional: Computation and Physical with implements some communication deeply embedded function in the that implements computing and design some function communication Interconnect: acts Requires a physical as the facilitators platform to run/to for physical communicate interactions CPS Design Flow Requires Model Integration Architecture Design Integrated Multi-physics/Cyber Design Detailed Design Modeling Exploration Modeling Simulation V&V& Modeling Analysis SW Physics-based Structure/CAD/Mfg Deep Rapid exploration Exploration with integrated optimization and V&V analysis • Design Space + • Design Space + Constraint • Architecture Constraint Modeling Modeling Modeling • Architecture Modeling • Dynamics, RT • Architecture • Dynamics Modeling Software, CAD, Modeling • Computational Behavior Thermal, … • Low-Res Modeling • Detailed Domain Component • CAD/Thermal Modeling Modeling Modeling • Manufacturing Modeling Domain Specific Modeling Languages Example: Architecture Modeling Sublanguage Formalism, Language Constructs, Examples Usage / Capability Systems Hierarchical Architect Module -Explore Architecture Interconnect Design Modeling - Components Space - Interfaces - Derive - Interconnects Candidate - Parameters Designs - Properties Hierarchically Systems Layered Architect Design Parametric Space - Define Alterna tives Design Modeling - Alternatives/ Space Options - Define - Parameters Constraint - Constraints Example: Dynamics Modeling Component Hybrid Bond Engineer Graphs - model - Efforts, dynamics Flows, with Hybrid Physical - Sources, Bond Graphs Dynamics Capacitance, System Inductance, Engineers Modeling - RitResistance, - Compose - Transformers system Gyrators, dynamics Dataflow + DiDomain Stateflow + TT Engineers Schedule - design controller Computational - Interaction Sensor Actuator System Dynamics with Phys ica l Processor Engineers Modeling Components Software - Cyber Topology - Processor Assembly Components allocate - Processing Allocation - Platform Components Effects Example: Physical Structure and Manufacturing Modeling Standard Structural Component Structural Interfaces (ex: SAE Engineer Interfaces #1) - Defines - Defined with Structural Solid Peer Roles: Interface Modeling -Axis System (CAD / - Point Engineer - Surface Geome try) - Defines - CAD Links Architecture Component Component MfCtManuf. Cost Engineer -Make Manufacturing - Material - Defines Modeling - Fab Proc Part Cost - Complxity - Defines - Shape/Wt Structural - OTS: Cost/unit Interface, Structural Fastener Interfaces - Fastener Types, Num# … 15 Model Integration Challenge: Physics Heterogeneity of Physics Electrical Mechanical Hydraulic Thermal Domain Domain Domain Domain Theories, Theories, Theories, Theories, Dynamics, Dynamics, Dynamics, Dynamics, Tools Tools Tools Tools Physical components are involved in multiple physical interactions (multi- phi)hysics) Challenge: How to compose multi-models for heterogeneous physical components Model Integration Challenge: Abstraction Layers Bt( )= κ ( Bt ( ),..., Bt ( )) Plant Dynamics Controller Dynamics: pj1 Models Models • Properties: stability, safety, performance • Abstractions: continuous time, functions, Heterogen signals, flows ,… Physical design eity SftSoftware SftSoftware Software : Bi()= κ ck ( B1 () i,..., B ()) i • Properties: deadlock, invariants, Architecture Component of security,… Models Code Ab • Abstractions: logical-time, concurrency, s Software design tractions atomicity, ideal communication,.. System Resource Systems : Bt(jpi )= κ ( Bt1 ( ),..., Bt ki ( )) Architecture Management • PtiProperties: tim ing, power, secur ity, fau lt Models Models tolerance System/Platform Design • Abstractions: discrete-time, delays, resources, scheduling, Cyber-physical components are modeled using multiple abstraction