1. Requirements Formulation: Document Management vs
Requirements Formulation: Document Management vs. Model Based System Engineering
Clifford Levine
April 24, 2017

2. Moving from document-centric to model-centric
Document Management
Past
Specifications
Interface requirements
System design
Analysis & Trade-off
Test plans
Future
Moving from document-centric to model-centric

3. Document Based Engineering
Requirements Management
Behavioral Analysis
Architecture Synthesis
Verification
Requirements
Database
Behavior
Database
Physical
Architecture
Database
Verification
Database
Drawing Packages
Spreadsheets
Simulation Packages
Word Processors
Spreadsheets
Drawing Packages
Spreadsheets
Testing Packages
Spreadsheets
Stovepiped efforts utilizing independent representations hides context, requires extraordinary data management, and complicates the SE effort

4. Model Based Systems Engineering
Behavior Domain
Source Requirements Domain
Originating requirements
trace to behavior
Data c
verified by
Behavior is allocated to
physical components
V&V Domain
Architecture Domain
Data
MODEL
Data
Utilizing a layered approach to progressively clarify and elaborate all four domains concurrently ensures consistency and completeness
verified by
verified by
Originating requirements trace to physical components
Vitech Corporation

5. 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

6. Requirements (Sources)
CONOP
Potential Source Documents
Vitech Corporation

7. Capturing Operational Concepts
Shared vision of stakeholders
Mission requirement(s)
Collection of scenarios involving external systems
Vitech Corporation

8. Requirements: Traceability
CONOP
Sources
Model
Tool
Vitech Corporation

9. Layered Approach Level Of Detail LEVEL 1 LEVEL 2 LEVEL n REQ BEH
Dgn V&V
ARCH
Source Documents
Docs
Level Of Detail
LEVEL 1
REQ
BEH
ARCH
DgnV&V
Docs
Docs
LEVEL 2
REQ
BEH
ARCH
Dgn V&V
Docs
Docs
LEVEL n
Must complete a layer before moving to the next layer (completeness)
Cannot iterate back more than one layer (convergence)
Vitech Corporation
MBSE - CORE 8

10. 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
The format for each view type is defined in the view generator
View generator contains format rules for each selected view type
System Design Repository:
Features of Elements &
Control/Connection Constructs
Vitech Corporation
MBSE - CORE 8

11. 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)
*We will step you through two ways to generate documentation.
Generic table output. Works great for Risk meetings. Customers and managers find this format easy to understand.
Then we will generate an SDD (system description document)
Vitech Corporation
MBSE - CORE 8

12. MBSE: Restoring Analytical Rigor, Efficiency, and Effectiveness
PowerPoint 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)

13. Thank You! For More Information
Vitech Website
Community
Presenter
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