Model -Based Systems Engineering: A Roadmap …

1 Model -Based Systems engineering : Model -Based Systems engineering Center1 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Systems engineering : A Roadmap for Academic ResearchChris ParedisAssociate DirectorModel -Based Systems engineering CenterGeorgia Collaborators Fried Augenbroe Leon McGinnis Russell Peak Yan Wang Ben Lee Brian Taylor Edward Huang George Thiers Kevin Davies2 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Reserved. Yan Wang Grad Students / Postdocs Aditya Shah Alek Kerzhner Axel Reichwein Kevin Davies Kysang Kwon Ola Batarseh Roxanne Moore Sebastian Herzig Stephanie Thompson Wladimir SchamaiContext: MBSE and Decision MakingAlternativesOutcomesIdeasKnowledge /BeliefsPreferencesDecision TheorySelection Criterion: E[u]3 MBSE Center2008-2011 Copyright Georgia Tech.

2 All Rights Reserved. Goal of MBSE: Improve Efficiency & Rationality Efficient =Perform the SE process with fewer resources Rational =Be consistent with designer s beliefs and preferences(Figure Adapted from G. Hazelrigg)Maximize E[u]Most PreferredSystem AlternativeDecision TheoryTarget for the MBSE Roadmap Improve Efficiency Reduce the cost and effort needed to identify, locate, access, and use informationImprove RationalityRationalitytarget4 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Reserved. Improve Rationality Make better decisions with the currently available information How can we help system engineers to design more efficiently and rationally?EfficiencycurrentObstacles on the MBSE Roadmap Obstacles for Efficiency: Creating models (manually) is expensive Performing analyses is time-consuming and cumbersome (due to lack of Rationalitytarget5 MBSE Center2008-2011 Copyright Georgia Tech.)

3 All Rights ) Rehashing the same information: , writing design review reports Maintaining dependencies between different Model views of the same system is error-prone and time-consumingEfficiencycurrentObstacle =Opportunity for ResearchObstacles on the MBSE Roadmap Obstacles for Rationality: Consistency: Are models in sync with each other? With data? Conform to language? Bounded rationality: too much information and knowledge for Rationalitytarget6 MBSE Center2008-2011 Copyright Georgia Tech. All Rights human to take into account and process Poor design methods: methods must be consistent with decision theory Distributed decision making: different people = different beliefs and preferences irrationalityEfficiencycurrentObstacle =Opportunity for ResearchProposed Path to Target Focus on efficiency first Establish benefits of MBSE early on Low-hanging fruit Address rationality Rationalitytarget7 MBSE Center2008-2011 Copyright Georgia Tech.

4 All Rights Reserved. Address rationality gradually Start with consistency Requires significant change in mindset for SE practitioners Requires further development of theory of Rational DesignEfficiencycurrentHow can we help system engineers to design more rationally and efficiently?Presentation Overview Context: MBSE and decision makingHow can MBSE help us make better decisions? Common theme in research: Model Transformations8 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Reserved. More efficient decision making with MBSE Modeling of system alternatives descriptive Predictive modeling of consequence analytical More rational decision making with MBSE How to formulatedesign decisions?MBSE Process = Model TransformationsInitialModelFinalModel Transformations 9 MBSE Center2008-2011 Copyright Georgia Tech.

5 All Rights LibrariesModel Transformationpre-image(pattern)matches? then generatepost-imageModel TransformationSource MetamodelSource ModelTarget MetamodelTarget Modelconforms toconforms toTransformation SpecificationTransformation Enginereadswritesrefers torefers toexecutes(Czarnecki, K., & Hellen, S., 2006)10 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Reserved. Transformation Specification isalso a Model automated generation of transformation engine code Origins Model Driven Architecture/ engineering Tools MOFLON, QVTo, ATL, GME/GReAT, VIATRA2, Kermeta,.. Example Usages: Automation of repeatedmodeling patterns Tool interoperation Document generation Consistency checking Dependency propagation(Czarnecki, K.)

6 , & Hellen, S., 2006)Presentation Overview Context: MBSE and decision makingHow can MBSE help us make better decisions? Common theme in research: Model Transformations11 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Reserved. More efficient decision making with MBSE Modeling of system alternatives descriptive Predictive modeling of consequence analytical More rational decision making with MBSE How to formulatedesign decisions?Modeling system Alternatives Some Issues SysML is well-suited for modeling a single is often not sufficient: Modeling product families Modeling Systems throughout the development process Modeling variants 12 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Reserved.

7 Modeling variants space of alternatives to be considered for design optimization Integration between many viewpoints, many in languages/tools other than SysML Maintaining consistency in the specificationGenerative Grammar for Design Synthesis Graph Transformation 13 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Reserved. Graph Transformation rules to generate Systems Generate random system alternatives by applying rules in randomized orderDecision Tree of Generation ProcessDecision TreeDecision Tree[Activity] act [ ]Add Cylinder [failure]{probability = ".7"} [success]Add CylinderAdd Directional [success] [failure]{probability = ".7" } [success]14 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Directional Valve{probability = ".}

8 3" } [success]{probability = ".7"}{probability = ".7" } [success]{probability = ".3" } [success]Add PumpAdd TankAdd Directional Valve{probability = ".3" } [success] [failure]{probability = ".7" } [success]{probability = ".3" } [success] [failure]{probability = ".3" } [success]Design Grammar Example 15 MBSE Center2008-2011 Copyright Georgia Tech. All Rights ModelTransformations((AlekAlek KerzhnerKerzhner, , MSMS Thesis)Thesis)Presentation Overview Context: MBSE and decision makingHow can MBSE help us make better decisions? Common theme in research: Model Transformations16 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Reserved. More efficient decision making with MBSE Modeling of system alternatives descriptive Predictive modeling of consequence analytical More rational decision making with MBSE How to formulatedesign decisions?

9 Analysis Modeling Some Issues Expanding the expressivity of parametrics: SysML4 Modelica for Differential Algebraic Equations ModelCenter for networks of black-box analysis models Model reuse through composition Composition knowledge in transformations17 MBSE Center2008-2011 Copyright Georgia Tech. All Rights Reserved. Composition knowledge in transformations Model context: assumptions, applicability Declarative, equation -Based modeling More efficient solving through symbolic manipulation Abstraction levels Best value: cost of creating/using Model vs. benefit Predictive modeling probability of future event Competing Requirements(Force, Total Time, Cost, Mass) Multiple Analyses (Fluid Power, Cost, Mass) Multiple use-phasesExample: Hydraulic Log SplitterLog Loading &Splitting AreaDirectionalControl ValveHydraulic Cylinder& RamEngine &Pump18 MBSE Center2008-2011 Copyright Georgia Tech.

10 All Rights Reserved. Multiple use-phases(Forward, Reverse) Many components to select from(credit: Dave Thompson)EngineDirectionalControl ValveCylinderTankLoadPumpHydraulic ConnectionMechanical TranslationalConnectionMechanical RotationalConnectionLogSplitterReqRequir ements[Package] req [ ]Id = " "Text = "The system shall be capable of fulfilling the requirement ForwardPhaseId = " "Text = "The system shall be capable of fulfilling the Hydraulic system Requirements." requirement HydraulicSystemId = "1"Text = " " requirement TotalSystemId = " "Text = "The system shall be capable of fulfilling the requirement ReversePhase deriveReqt Problem Definition: Requirements DecompositionHierarchy of RequirementsHydraulicReverse PhaseForwardPhase19 MBSE Center2008-2011 Copyright Georgia Tech.