Requirements Formulation: Document Management vs. Model Based System Engineering Clifford Levine 16 March 2018
Document Management Past Future • Specifications • Interface requirements • System design • Analysis & Trade-off • Test plans Moving from document-centric to model-centric
Document Based Engineering Requirements Management Requirements Database Word Processors Spreadsheets Behavioral Analysis Behavior Database Drawing Packages Spreadsheets Simulation Packages Architecture Synthesis Physical Architecture Database Drawing Packages Spreadsheets Verification Database Testing Packages Spreadsheets Stovepiped efforts utilizing independent representations hides context, requires extraordinary data management, and complicates the SE effort
Model Based Systems Engineering Behavior Domain Originating requirements trace to behavior Data c Source Requirements Domain verified by Behavior is allocated to physical components V&V Domain Data Architecture Domain MODEL verified by Originating requirements trace to physical components 4 Vitech Corporation Data
MBSE Activities Timeline – Top Down 0. Define Need & System Concept 1. Capture & Analyze Orig. Requirements Can be restructured for middle out and reverse engineering projects. 2. Define System Boundary 3. Capture Originating Architecture Constraints 4. Derive System Threads 5. Derive Integrated System Behavior 6. Derive Component Hierarchy SCHEDULE 7. Allocate Behavior to Components 8. Define Internal Interfaces 9. Select Design 10. Perform Effectiveness & Feasibility Analyses 11. Define Resources, Error Detection, & Recovery Behavior 12. Develop Validation Requirements/Validation Plans 13. Generate Documentation and Specifications
Requirements (Sources) Potential Source Documents 6 Vitech Corporation
Capturing Operational Concepts § Shared vision of stakeholders § Mission requirement(s) § Collection of scenarios involving external systems 7 Vitech Corporation
Requirements: Traceability Sources Model Tool 8 Vitech Corporation
Layered Approach Dgn V&V BEH Source Documents REQ ARCH LEVEL 1 Dgn V&V BEH Docs REQ ARCH Docs LEVEL 2 Dgn V&V BEH Docs REQ LEVEL n ARCH Docs Must complete a layer before moving to the next layer (completeness) 9 Vitech Corporation iterate back more than one layer (convergence) Cannot Level Of Detail
View Generators Using a Common Repository Guarantee Consistent Views • A graphical view is defined by features and a format • The features are in the repository View generator contains format rules for each selected view type System Design Repository: Features of Elements & Control/Connection Constructs 10 Vitech Corporation • The format for each view type is defined in the view generator
Automated Documentation Generation System Design Repository § Provided from the engineering database (from the start) • Uses scripts to generate document files in RTF, HTML, & ASCII format; you publish in your word processor (e. g. , Microsoft Word) • Captures any internal graphic in WMF, JPEG, PNG, & SVG format • Prints to any device if driver available, (e. g. , laser, Postscript, plotter) 11 Vitech Corporation
MBSE: Restoring Analytical Rigor, Efficiency, and Effectiveness Power. Point Engineering (Common Practice) Model-Based SE (Improved Practice) Independent drawings Consistent views Static diagrams Executable behavior Data storage Linked repository Stored views Dynamic view generation Ad hoc process (inconsistent results) Repeatable process (consistent results) Manual change propagation across all affected products (by the systems engineer) Automatic change propagation across all current and future products (by the engineering environment)
Thank You! For More Information § Vitech Website http: //www. vitechcorp. com/ § Community http: //community. vitechcorp. com/home/ § Presenter zscott@vitechcorp. com We invite your comments and questions on the Community website at http: //community. vitechcorp. com/forum/
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