1. Model Based Systems Engineering
NASA PM Challenge 2009
February 25, 2009
Sanford Friedenthal
sanford.friedenthal@lmco.com

2. Topics
MBSE Motivation and Scope
System Modeling Using SysML
System Model as an Integration Framework
INCOSE MBSE Initiative
MBSE Observations
Summary

3. MBSE Motivation and Scope

4. SE Practices for Describing Systems
Past Future
Specifications
ATC Pilot Airplane
Interface requirements Request to proceed
Authorize
Initiate power-up
System design Power-up
Report Status
Analysis & Trade-off Direct taxiway
Initiate Taxi
Executed cmds
Test plans
Moving from Document centric to Model centric

5. Model-based Systems
Engineering (MBSE)
Life Cycle Support
Formalizes the practice of
systems engineering through
the use of models
Broad in scope
– Integrates with multiple
modeling domains across life
cycle from SoS to component
Vertical Integration
Results in quality/productivity
improvements & lower risk
– Rigor and precision
– Communications among
system/project stakeholders
– Management of complexity

6. MBSE Benefits
Improved quality
– Early identification of requirements issues
– Enhanced system design integrity
– Improved specification of allocated requirements to HW/SW
– Fewer errors during I&T
– More rigorous requirements traceability
Increased productivity
– Improved impact analysis of requirements changes
– Reuse of existing models to support design/technology
evolution
– Auto-generation of documentation
Reduced risk
– Improved cost estimates
– Early/on-going requirements validation & design verification

7. System Modeling Using SysML

8. System Modeling
Requirements
Functional/Behavioral Model Performance Model
Start Shift Accelerate Brake Control Power Vehicle
Input Equations Dynamics
Mass
System Model Properties
Model
Structural
Model
Safety
Model
Cost
Engine Transmission Transaxle Model
Structural/Component Model Other Engineering
Analysis Models
Integrated System Model Must Address
Multiple Aspects of a System

9. What is SysML?
A graphical modeling language in response to the
UML for Systems Engineering RFP developed by the
OMG, INCOSE, and AP233
– a UML Profile that represents a subset of UML 2 with
extensions
Supports the specification, analysis, design,
verification, and validation of systems that include
hardware, software, data, personnel, procedures, and
facilities
Supports model and data interchange via XML
Metadata Interchange (XMI®) and the evolving AP233
standard (in-process)
SysML is Critical Enabler for MBSE

10. 4 Pillars of SysML – ABS Example
1. Structure sd ABS_ActivationSequence [Sequence Diagram] 2. Behavior
stm TireTraction [State Diagram]
m1:Brake
interaction
d1:Traction
Detector Modulator
LossOfTraction state
machine
detTrkLos()Gripping Slipping
activity/
RegainTraction
sendSignal() function
modBrkFrc(traction_signal:boolean)
modBrkFrc()
definition use
sendAck()
3. Requirements 4. Parametrics

11. OMG SysML™ Specification
Specification status
– Adopted by OMG in May ’06
– Available Specification v1.0 in Sept ’07
– Available Specification v1.1 in Nov ‘08
– Revision task force for v1.2 in process
Multiple vendor implementations available
Information can be found on the OMG SysML
Website at http://www.omgsysml.org/

12. System Model as an
Integration Framework

13. System Architecture Model
as Integrating Model
Requirements
Mgm’t
Repository
System Architecture Model Verification Models
Analysis Models
U(s) G(s)
∫
&
Req’ts Allocation
Design Integration
Hardware Models Software Models
SET
S Q
R CLR Q

14. System Architecture Model
Specifications Adaptive Resource Management Theater-Level
Theater-Level
Policy-Selected Mission Priority
Resource Mission Priority
Resource Allocation Control
Control
QoS Spec Manager
Manager Algorithms
QoS Spec
Modifications
Modifications
Globus
System / /QoS Host Load
Host Load Network Load
Network Load
System QoS QoS Managers
Specifications Analyzer
Analyzer Analyzer
Analyzer
Specifications
Monitor Control
Collector / /
Collector History Host
Host Hardware Fault
Hardware Fault Application
Application
Correlator
Correlator Servers Discovery
Discovery Detection
Detection Control
Control
Application Quasar OS-Level
Application UNIX and WinNT Remos Network Quasar OS-Level UNIX and NT App
Remos Network Feedback UNIX and NT App
Instrumentation OS Monitors Monitoring Feedback Control Agent
Instrumentation Monitoring Adaptation Control Agent
Adaptation
Applications
Applications
System Architecture Model Can Integrate Across Domains
© Copyright Lockheed Martin Corporation All Rights Reserved

15. Using the System Architecture Model
to Flowdown Requirements
System-of-System Level Trade Studies,
UC
• 1st Level Of Decompositions
• How Our System Contributes to Simulation,
the Overall Mission Specification Reviews,
System 1 ..... System 2
Spec
etc.
Spec
Mission Concept of Operations
Behavior,
System Level Structure &
• Derives Subsystems Requirements
• Allocates Requirements to Subsystems Trade Studies,
UC
Simulation,
Specification Reviews,
Sub- Sub etc.
System 1
... System 2
A-Spec Spec Spec
Element Level Behavior,
Structure &
• Derives Hardware and Software Components
Requirements
• Allocates Requirements to Components Trade Studies,
UC
Simulation,
Specification Reviews,
SW SW etc.
B-Spec Comp 1 ... Comp X
Spec Spec
Component Design Behavior,
Structure &
& Implementation Level Requirements
UC
(from John Watson/LMC
SysML Info Days presentation) Comp 1
Software
... Comp X
Software
© Copyright Lockheed Martin Corporation All Rights Reserved

16. System Decomposition Process UC
.....
Analyze System Level Requirements Input SatComms
Forward Message from
Regional Command
Weapon System Weapon
Receive Order
Evaluate Engagement
Start Enagement
Fire Weapon
Monitor Weapon
[Status Change]
[Correction Needed]
Analyze System Services [No]
Weapon Intercept?
Terminate Engagement
Send Guidance Command
Correct Course
Forward Message to Send Status Change
Regional Cmd
Forward Message to
Regional Cmd
Identify the Subsystem
SatComms Weapon System Weapon
Forward Message from
Regional Command
Receive Order
Evaluate Engagement
Analyze Subsystem Collaboration to
Start Enagement
Fire Weapon
Monitor Weapon
[Status Change]
[Correction Needed]
[No] Send Guidance Command
Weapon Intercept?
Satisfy the System Services Forward Message to
Regional Cmd
Terminate Engagement
Send Status Change
Correct Course
Forward Message to
Regional Cmd
UC
Incorporate Additional Trade Studies, R&D,
Analysis as Needed Simulation, Specification
Reviews, etc. .....
Derive and Allocate
The Subsystem shall ....
Requirements to Subsystem The Subsystem shall ....
Derived
Requirements
Yes
Continue?
No
Complete Subsystem Specs
(from John Watson/LMC
SysML Info Days presentation)
© Copyright Lockheed Martin Corporation All Rights Reserved

17. Typical Specification Tree
req.pkg.Specification.Tree «Requirements Diagram»
«Requirement» «Requirement»
Mission Requirements Specification Concept Of Operations
«trace» «trace»
«Requirement»
System Requirements Specification
ID = SC.00x
«trace» «trace»
«Requirement» «Requirement»
Module A Requirements Specification Module B Requirements Specification
ID = MB.00x
«trace» «trace» «trace»
«Requirement» «Requirement»
Subsystem 1 Requirements Specification Subsystem 2 Requirements Specification
ID = SS2.00x
© Copyright Lockheed Martin Corporation All Rights Reserved

18. Space Vehicle Doman
bdd.pkg.Structure.SpaceVehicleDomain «Block Definition Diagram»
«block»
«block» Space Vehicle Domain
Environment 1 1
1
«block,enterprise»
Space Vehicle Enterprise
0..*
Crew «block» «block»
Ground Control 1 1 Ground Support
«block»
1 1
«block» Launch Vehicle
1
Launch Stack 1
«block» «block» «block»
1 1 1 1
Space Vehicle Mission Control Ground Handling
© Copyright Lockheed Martin Corporation All Rights Reserved

19. Space Vehicle Context
External Interfaces
ibd.block.Domain.SpaceVehicleInContext «Internal Block Diagram»
«block,enterprise»
Space Vehicle Enterprise
1 sc:Space Vehicle
1 grndctrl:Ground Control
Attributes
mass:int
center of mass:int
1 flghtctrl:Mission Control moment of inertia:int
fuel:int
1 ghte:Ground Handling Operations
Execute Burn():void
Calculate Burn Parameters():void
Evaluate Position():void
1 grndctrl:Ground Control Sense Position():void
InitManeuver()
1 lv:Launch Vehicle
© Copyright Lockheed Martin Corporation All Rights Reserved

20. Typical System Use Cases
uc_pkg_Domain_ControlOrbit
SpaceVehicle System
Crew
Control Orbit
«include»
«include»
Mission Control
Translate Vehicle Rotate Vehicle
© Copyright Lockheed Martin Corporation All Rights Reserved

21. Translate Vehicle Activity Diagram
act_uc_SpaceVehicle_TranslateVehicle
cdh:CandDH gnc:GNC prop:Propulsion
Crew Cmd
targetPos:Quaternion
Receive Calculate
Command Burn
for Burn Parameters
currentPos:Quaternion [targetPos==CurrentPos]
FlgthCtrl Cmd initAbort:Command «continuous» propCmds:Command
pin_5:Quaternion
Execute
Evaluate
Burn
Position propCmds:Command
thrust:Newtons
currentPos:Quaternion
Thrust
«continuous»
currentPos:Quaternion
Sense
Sensor input Current
sd:Data Position
© Copyright Lockheed Martin Corporation All Rights Reserved

22. Space Vehicle Hierarchy
bdd.pkg.Structure.Subsystems «Block Definition Diagram»
«block»
Space Vehicle
1 1 1 1
«block,Subsystem» «block,Subsystem» «block,Subsystem» «block,Subsystem»
Propulsion GNC CandDH Electrial Power Supply
© Copyright Lockheed Martin Corporation All Rights Reserved

23. Space Vehicle Internal Block Diagram
ibd.block.Spacecraft.Subsystems «Internal Block Diagram»
1 DomainLevel::Structure::Space Vehicle Enterprise.sc:Space Vehicle
1 eps:Electrial Power Supply
elec1:Power elec2:Power
elec1:Power elec2:Power
1 ct:CandDH 1 gnc:GNC
cmd2:Command
cmd:Command sd:Data sd:Data
cmd:Command cmd2:Command
propCmd:Command
1 prop:Propulsion
thrust:Newtons propCmd:Command
thrust:Newtons
© Copyright Lockheed Martin Corporation All Rights Reserved

24. Georgia Tech Research Project
Integrating System Design Model with Simulation & Analysis Models

25. System Objective Function
Excavator SysML Parametrics
n n
GIT Project f = ∑ k moe + ∑ k moe moe
i i ij i j
i =1 i , j =1;i , ≠ j

26. Excavator System Breakdown
GIT Project

27. Simulation in Dymola
GIT Project
Modelica
Lexical Representation
(auto-generated from SysML)
[Johnson, 2008 - Masters Thesis]

28. Typical Integrated Tool
Environment
Project Management
SoS/Enterprise Modeling
Requirements Management
Product Data Management
UPDM
Simulation & Visualization
Verification & Validation
Engineering Analysis
System Modeling
SysML
CM/DM
Software Modeling Hardware Modeling
UML 2.0 VHDL, CAD, ..

29. INCOSE MBSE Initiative

30. INCOSE MBSE Initiative Charter
Promote, advance, and institutionalize the practice of
MBSE to attain the MBSE 2020 Vision through broad
industry and academic involvement in:
– Research
– Standards
– Processes, Practices, & Methods
– Tools & Technology
– Outreach, Training & Education

31. Integrated Systems Engineering Vision
Hydraulic
Fluid:
SAE 1340
not-
Power compliant
Rating:
18 Amps
Thermal/He
at
Dissipation:
780°
Ergonomic/P
edal
Feedback: 34
ERGS
Hydraulic
Pressure:
350 PSI
Sensor
MTBF:
3000 hrs
Minimum Turn Radius: 24 ft.
Minimum Turn Radius: 24 ft.
Dry Pavement Braking Distance at
Dry Pavement Braking Distance at
60 MPH : 110 ft. 90 ft
60 MPH: 110 ft. FIGURE NOT INCLUDED IN VISION

32. Challenge Teams
Telescope System Modeling – Robert Karban (ESO)
Space Systems – Chris Delp *
Mechatronics / Model Interoperability Team – Russell Peak (GIT)
GEOSS Architecture Modeling – Larry McGovern
Intelligent Enterprises – Jack Ring *
INCOSE Enterprise Model – Michael Dee (Regina Griego)
MBSE Applied to Urban Transportation – Larry Head (UofA)
Avionics Systems and Software Integration – Leon Corley

33. INCOSE Telescope Modeling Challenge Team
Robert Karban – Lead
APE Project
APE will be installed at the telescope in
the Chile desert.

34. Model Organization
Telescope MBSE
Challenge Team Site
http://mbse.sysmod.de/
Presented to the INCOSE 2008 Symposium by Robert Karban

35. MBSE Observations

36. MBSE Observations
Transition from document-centric to model-centric
is a cultural change
Well defined MBSE method is essential
Multiple tool vendors providing a range of price
point, capability, and standards conformance
MBSE training should include language, method,
and tools
Employ pilots to validate your MBSE approach
Scope model based on program objectives and
constraints
A lot has been learned, but much more remains

37. Summary

38. Summary
MBSE is a key practice to advance complex systems
development
Standards such as SysML are critical enablers of MBSE
Multiple tool vendors implementing the standard
System architecture model and standards based
approach facilitate Integration across modeling domains
Growing interest and application of MBSE
INCOSE MBSE helping to advance and promote MBSE

39. MBSE References
(there are many more)
INCOSE MBSE Connect Site
– http://www.incose.org
Multiple INCOSE Journal/Insight Articles, Symposium Papers
OMG SysML Website
– http://www.omgsysml.org
SE^2 Telescope MBSE Challenge Team Site
– http://mbse.sysmod.de/
Estefan, Jeff “Survey of Candidate Model-Based Systems Engineering (MBSE)
Methodologies”, Rev. B, May 23, 2008
Cantor, Murray, Rational Unifi ed Process ® for Systems Engineering, RUP SE Version 2.0,
IBM Rational Software white paper, IBM Corporation, May 8, 2003
Hoffmann, Harmony-SE/SysML Deskbook: Model-Based Systems Engineering with Rhapsody,
Rev. 1.51, Telelogic/I-Logix white paper, May 24, 2006
Lykins, Friedenthal, Meilich, Adapting UML for an Object-Oriented Systems Engineering
Method (OOSEM), Proceedings of the INCOSE International Symposium. Minneapolis, July
15–20, 2000
Friedenthal, Moore, Steiner, ”A Practical Guide to SysML: The Systems Modeling Language”
Morgan Kaufmann, 2008
Tim Weilkiens, “Systems Engineering with SysML/UML” Morgan Kaufmann, 2008
Wymore , W. , Model-Based Systems Engineering, CRC Press , 1993

40. Backup

41. INCOSE Telescope Modeling Challenge Team
Robert Karban – Lead
APE Project
APE will be installed at the telescope in
the Chile desert.

42. Model Organization
SE^2 Telescope MBSE
Challenge Team Site
http://mbse.sysmod.de/
Presented to the INCOSE 2008 Symposium by Robert Karban

43. System Context
3 modeling
approaches for
interfaces
Presented to the INCOSE 2008 Symposium by Robert Karban

44. High Level Structure
Example for system structure: “Product tree” of Opto-Mechanical Bench
Presented to the INCOSE 2008 Symposium by Robert Karban

45. Traceability
Example for automatic dependency matrix
between objective and user requirements:
Presented to the INCOSE 2008 Symposium by Robert Karban