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SYS 5390 Lecture #2, Slide 1
Model BasedCollaborative Systems Engineering
Stphane Bucaille, PhDElectrical and Computer Engineering Department
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SYS 5390 Lecture #2, Slide 2
GeneralInformation
Product/Teamarchitectureprinciple
SysML
Overview
Example
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SYS 5390 Lecture #2, Slide 3
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SYS 5390 Lecture #2, Slide 4
General Information
JPL project
Objective: Design a model for the electrical systems of a
generic spacecraft
Software: Magic Draw
JPL visit
Career fair
Additional recommended book
The Engineering Design of Systems: Models and Methods
(Wiley Series in Systems Engineering and Management),Dennis M. Buede, 2nd edition, 2009
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SYS 5390 Lecture #2, Slide 5
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SYS 5390 Lecture #2, Slide 6
Model
Toothbrush
head
Toothbrush
base
Toothbrush
body
Viewpoints
Perceptions
System
Toothbrush
head
Toothbrush
body
Toothbrush
base
Interface(external, i.e. with environment)
Interface
(internal)
System: a collection of (hardware, software & humanware) systems organized in order that
theirintegration allows to accomplish within a specificenvironment the missions it was
designed for
Systems overview
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Electronic
toothbrush
Users
Maintenance
Power
Internet
External
system
Externalsystems
External system
Internal
integration
External
integration
Basis
Internal sub-systems
Embedded
system
Corpse Head
Sales
Hardware systems
Software systems
Human systems
Introduction to MBSE
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ViewpointAnswers to
the question
Some associated
keywords
Examples
(e-toothbrush)
Operational Why ?
Operational
context, mission,
use case
Clean & healthy
teeth, gain of time,
fashion bathroom
Functional What ?
Service, function,
task, operation &
mode of operation
Brushing, speed
regulating,
brushing strength
programming
Constructional How ?
Component,
technical
architecture &
configuration
Head, base,
corpse, speed
regulator
Introduction to MBSE
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ConstructionalTo be
What the system shall be?
OperationalTo expect
What could be the problem?
FunctionalTo do
What the system shall do?
DynamicsStaticsControl
Lifecycle
(behavior)
Operational
contexts
(mission)
Operational
scenarios
(scenario)
Operation
mode
(behavior)
Function
(operation)
Functional
dynamic
(scenario)
Configuration
(behavior)
Ressource
(organization)
Constructional
dynamic
(scenario)
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States Static structure Dynamic behavior
Operationalvision
Functionalvision
Constructionalvision
Electronic
toothbrush
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The key system problem in practice: how to make the systems
stakeholders converge on a same vision of the same system?
Stakeholder 1
Stakeholder 2Stakeholder 3 Stakeholder 4
Human
system
Key human
problem:
CONVERGENCE
System 1System 3
System 2 System 4
Technical
system
Key technical
problem:
INTEGRATION 1
(to be prepared
as early as
possible)
1 I.e. defining the interfaces
Towards the Product / Team
Architecture Principle
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Chief
Architect
External
support
ProjectManager
Security
Verification
Engineer
Technical
Managers
Customer
Validation
Engineer
A system architect must interact
and take into account multiplecultures and stakeholders
System
Architect
User
Platform
director
Subsystems
directors
Industrial
Managers
Modules
managers
Towards the Product / Team
Architecture Principle
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Chief
Architect
Security / Quality
Engineer
Project
Manager
Industrial
Managers
Customer
UserNeeds
QualityDesign
Technical
Managers
Each stakeholderhas his own territoty and his skills.
He also interacts with the other stakeholders.
Planning
SystemD
esign
System
Architect
Validation
Validation
Engineer
DesignExpertise
Security/Quality
Expertise
Industrialization
Platform / Sub-
systems / ModulesDirectors
Management
Key difficulty: Identify and
manage organization interfaces
Towards the Product / Team
Architecture Principle
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Project
ManagerPlanning
Designer
(fashion)Design
MarketerNeeds
Engineer
TechnicalDesign
OrthodontistHealth
Beta-tester
REX
Industrial
EngineerIndustrialisation
Electric toothbrush stakeholders
Towards the Product / Team
Architecture Principle
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15
System
?
?
?? ?
?
? ?
?
?
?
What are the stakeholders of yoursystem of interest? Once you abstracted them,
identify theirrole and skills, and the way they interact.
Towards the Product / Team
Architecture Principle
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NEED
REQUIREMENT
TECHNOLOGICAL OPPORTUNITY
DEMONSTRATION
Whole consistency: animate & organize a
common system properties referential
A stakeholder shall
The system shall
A shall prove
that the system satisfies
A technology can
Needs referential
Technologicalopportunities
referential
Requirements referential
Demonstrationsreferential
Towards the Product / Team
Architecture Principle
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Caption
Is responsible of
Non
technological
environment
Sub-
systems &
modules
Product system
Project system
Use
cases
De-
mons-
tra-
tions
Needs Product requirements
Functional analysisInputs Outputs
REFERENTS
PM
Technologies
System
referentialsan
imation
(arc
hitecture,methods,tools,etc.)
QUALITY
Needs referential
T2M T3MT1M
Technologicalopportunities
referential
Requirements referential
Demonstrations
SS1 SS2 SS3 SS4
SS5 SS6
Involvement
Technological
needs Technological solutions
& proposals
Laboratory
(demonstrator)
LABO
Demosreferential
CT
Prod. M
TM
LM
QM
The Product / Team Architecture
Principle
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The RACI tool(s) R Responsible:
Those who do the work to achieve the task.There is typically one role with a participationtype of Responsible, although others can bedelegated to assist in the work required.
A Accountable The one ultimately accountable for the correct
and thorough completion of the deliverable or
task, and the one to whom Responsible isaccountable. In other words, an Accountablemust sign off (Approve) on work thatResponsible provides. There must be only one
Accountable specified for each task ordeliverable.
C Consulted Those whose opinions are sought; and with
whom there is two-way communication.
I Informed Those who are kept up-to-date on progress,often only on completion of the task ordeliverable; and with whom there is just one-way communication.
Variations RASCI, RACI-VS, RACIO, DACI, RSI, PARIS,
PACE, OARP
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Paradigm Analytical Architectural
Key principle Exhaustive understanding Global understanding
Perimeter Homogeneous systemHeterogeneous integrated
system
Building blocks Disciplinary knowledge Systems & interfaces
Mindset Uniqueness & certainty Diversity & relativity
Description mode Detailed representation Perceptions & viewpoints
Working mode Assembling Integration
Interaction mode Expertise & local Collaborative & global
Industrial specialist Engineer Systems architect
Paradigm opposition leads to acceptation and implementation difficulties!
Be didactic
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SYS 5390 Lecture #2, Slide 21
SysML purpose and Key Features
SysML is a general-purpose graphical modeling languagethat supports the analysis, specification, design,verification and validation of complex systems Systems might include hardware, software, data, personnel,
procedures, facilities, organizations
Links established with UML and VHDL for components designs
SysML can represents the following aspects: Structural composition, interconnection and classification
Function-based, message-based, and state-based behavior
Constraints on the physical and performance properties
Allocations between behaviors, structures and constraints(= functions allocated to components)
Requirements and their relationship to other requirements,design elements and test cases
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SYS 5390 Lecture #2, Slide 22
SysML Diagram overview
9 diagrams enable the complete engineeringprocess
Constraints apply to each diagram type Ex: an activity diagram
Can contain elements that represent actions, control flow andinput/output flow
But cannot contain elements for connectors and ports
SysMLDiagram
BehaviorDiagrams
ActivityDiagram
SequenceDiagram
StateMachineDiagram
Use CaseDiagram
RequirementDiagram
StructureDiagrams
BlockDefinitionDiagram
Internal BlockDiagram
ParametricDiagram
PackageDiagram
Same as UML
Modified from UML
Not in UML
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SYS 5390 Lecture #2, Slide 23
SysML Diagram details
Activity diagram represents behavior in terms of the ordering ofactions based on the availability of inputs, outputs, controls,
and how the actions transform the inputs to outputs
Sequence diagram represents behavior in terms of a sequence ofmessages exchanged between parts
State machine diagram represents behavior of an entity in terms ofits transitions between states triggered by events
Use case diagram represents functionality in terms of how asystem or entity is used by external entities (actors) to accomplish aset of goals
BehaviorDiagrams
ActivityDiagram
SequenceDiagram
StateMachineDiagram
Use CaseDiagram
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SYS 5390 Lecture #2, Slide 24
SysML Diagram details
Requirement diagram represents text-based requirements and
their relationship with other requirements, design elements,
and test cases to support requirements traceability
Requirement Diagram
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SYS 5390 Lecture #2, Slide 25
SysML Diagram details
Block definition diagram represents structural elements called
blocks, and their composition and classification
Internal block diagram represents interconnection and interfaces
between the parts of a block
Parametric diagram represents constraints on property values,such as F=m*a, used to support engineering analysis
Package diagram represents the organization of a model in
terms of packages that contain model elements
StructureDiagrams
BlockDefinitionDiagram
InternalBlock
Diagram
ParametricDiagram
PackageDiagram
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SYS 5390 Lecture #2, Slide 26
SysML and comparison with TTDSE(Traditional Top-Down Systems Engineering)
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SYS 5390 Lecture #2, Slide 27
Using SysML in support of MBSE
SysML enables the capture of the modeling information as part
of an MBSE approach without imposing a specific method on
how it is performed.
The selected method determines
Which activities are performed
The ordering of the activities
And which modeling artifacts are created to represent the system
Examples:
Traditional structured analysis
Use case driven approach
Different methods might produce different combinations of
diagrams
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SYS 5390 Lecture #2, Slide 28
Typical use
Capture and analyzeblack box system
requirements
Develop one or morecandidate systemarchitectures to
satisfy therequirements
Perform engineeringand trade-off analysisto evaluate and select
the preferredarchitecture
Specify componentsrequirements andtheir traceability to
system requirements
Verify that the systemdesign satisfies the
requirements byexecuting system-
level cases
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SYS 5390 Lecture #2, Slide 29
Typical use
Capture and analyzeblack box system
requirements
Capture text-based requirements in a requirementmanagement tool
Import requirements into the SysML modeling tool
Identify top-level functionality in terms of use cases
Capture the traceability between the use cases and
requirements Model the use case scenarios as activity diagrams, sequence
diagrams, and/or state machine diagrams
Create the system context diagram
Identify test cases to support system verification
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SYS 5390 Lecture #2, Slide 30
Typical use
Develop one or morecandidate system
architectures to satisfythe requirements
Decompose the system using theblock definition diagram
Define the interaction among the partsusing activity or sequence diagram
Define the interconnection among theparts using the internal block diagram
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SYS 5390 Lecture #2, Slide 31
Typical use
Perform engineering andtrade-off analysis to
evaluate and select thepreferred architecture
Capture the constraints on system properties usingthe parametric diagram to support analysis of
performance,
reliability,
cost, or other critical properties
Perform the engineering analysis to determine thebudgeted values of the system properties (typicallydone with a separate tool)
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SYS 5390 Lecture #2, Slide 32
Typical use
Verify that the systemdesign satisfies the
requirements by executingsystem-level cases
Capture the functional, interface, andperformance requirements for eachcomponent (block) in the architecture
Verify that the system design satisfiesthe requirements by executingsystem-level test cases
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SYS 5390 Lecture #2, Slide 33
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SYS 5390 Lecture #2, Slide 34
Problem summary
Marketing analysis shows needs to: increase automobile acceleration
fuel efficiency
MBSE selected aspects here to support initial trade-off analysis
Engine 4-cylinder engine
6-cylinder engine
vehicle controller and associated software to control air-mixture
maximize fuel efficiency and engine performance
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SYS 5390 Lecture #2, Slide 35
SysML Diagram
Header Frame
Content
A t bil ifi ti t
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SYS 5390 Lecture #2, Slide 36
Automobile specification capture:
Requirement Diagram
Depicts requirements usuallycaptured in a text specification
Shown in a containmenthierarchy
Relations types derive
satisfy verify
refine
trace
copy
with other requirements,
design elements
test cases
Top-level
requirement
Lower-level
requirement
Crosshair symbol:
Containment relationship
Each requirement includes:
Unique identification
Text Other properties
Verification status
Rationale
Risks
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SYS 5390 Lecture #2, Slide 37
Define the Vehicle and its external environment:
Block Definition Diagram
Block: general modeling concept used to model entities (SYS, HW, SE, physical objects,
abstract entities The Block Definition Diagram captures the relation between blocks such as block hierarchy
Top-level
Block
Driver, Passenger
subclasses of
vehicle occupant
Diamond symbol:
Contains relationship
Sys of Interest:
Car
External blocks
External
entities: # from
0 to unlimited
Ex: Traffic light
Blocks also include:
Properties
Behaviors, in
terms of activities
allocated to the
block
Operations of the
block
Ports (Interfaces)
U C Di
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SYS 5390 Lecture #2, Slide 38
Use Case Diagram
forOperate Vehic le
Use case diagram forOperate Vehicle depicts the major functionality for operating the vehicle
Use Case define how the system is used to achieve a user goal. The goals are accomplished by interactions between the actors and the subject. (Sequence Diagram)
Other Use Case Diagrams can represent how the system is used across its life cycle
Relate Use Cases to Requirements using refine relationship
Actor
(external)
Subject of the Use Case
(Used by the actors)
Represent ing Drive Vehic le Behavior
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SYS 5390 Lecture #2, Slide 39
Represent ing Drive Vehicle Behavior
Sequence Diagram
Sequence diagram specifies the interaction
between the Driverand the Vehicle as indicated by the names at the top of the lifelines
Time proceeds vertically down the diagram
The interaction occurrences each reference a more
detailed interaction (ref). The reference interaction is
another sequence diagram
These three interactions Control Power, Brake and
Direction occur in parallel (par)
These three interactions Control Neutral, Forwardand
Reverse occur in alternative (alt)
Reverse Powerinteraction occurs as a condition of the
vehicle state is reverse. (State Machine Diagram)
St t V hi l
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SYS 5390 Lecture #2, Slide 40
Start Vehic le
Referenced Sequence Diagram
Sequence diagram depicts an interaction that is referenced in the previous sequence diagram.
Sequence diagrams can include multiple message exchanges between multiple lifelines thatrepresent interacting entities.
Sequence diagrams provides considerable additional capability to express behavior that includes other message types,
Timing constraints
Additional control logic
the ability to decompose the behavior of a life line into the interaction of its parts
Driver sends a message to the
vehicle to start.
Message is synchronous
(filled arrowhead): operationcall that specify a request for
service)
Arguments of the operation call
represent the input data andreturn
The Vehicle responds with
the Vehicle on replymessage (dashed line).
The message is
asynchronous (open
arrowhead): the sender
does not wait for a reply
Once the reply has been
received, the driver and vehicle
can proceed to the next
interaction
C t l P
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SYS 5390 Lecture #2, Slide 41
Contro l Power
Activity Diagram
Activity Diagram is a more efficient representation of continuous types of behaviors
such as Control Power, Control Brakes, orControl Direction Activity Diagram shows the actions required of the Driverand the Vehicle to Control Power
Contains semantics for precisely specifying terms of the flow of control, inputs and outputs
Action output:Accelerator Cmd,
continuous= Input to the Provide Power
action
Initial node: Execution start.
Transition to the Control
Accelerator Position is performedby the Driver
Activity Partitions (Swimlanes): Actions in the
partitions specify functional requirements that
the Driverand the Vehicle must perform
Action output: TorqueContinuous torque generated
by the wheels to the road to
produce the force thataccelerates the Vehicle
Drive Vehic le States
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SYS 5390 Lecture #2, Slide 42
Drive Vehic le States
State Machine Diagram State Machine diagram shows the states of the
Vehicle and the events that can triggera transition
between the states. It can specify the life-cycle of blocks in terms of its
states and transitions
When the Vehicle is ready to be driven, it starts in the vehicle offstate
An ignition offevent triggers the transition back to the vehicle offstate
The text indicates the turn off vehicle behavior is executed prior to
entering the vehicle offstate
//
An ignition on event triggers the transition back to the vehicle on state
The text indicates the start vehicle behavior is executed prior to
entering the vehicle on state
After entry to the vehicle on state,
Vehicle immediately transitions to
the neutralstate.
A forward selectevent triggers a transition to the forwardstate if the
guard condition[speed>=0]is true.
In this state, the Vehicle performs the Provide Powerbehavior in the
previous activity diagram.
The neutral selectevent triggers a transition back to the neutralstate.
A reverse selectevent triggers a transition to the reverse state if the
guard condition [speed
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SYS 5390 Lecture #2, Slide 43
Vehicle Con text
Internal Block Diagram
Internal Block Diagram describes Vehicle context.
It shows the interfaces between the Vehicle, the Driver, and the Physical Environment(i.e. Road,Atmosphere, External Entity), cf. Block Definition Diagram
It represents the internal structure of a higher level block (bddAutomobile Domain block).
Item Flow: represents the
item flowing between parts
May include mass, energy,
informationInputs and Outputs from the
activity diagram are allocated
to the item flows on the
connectors.
Ports (Flow port, Standard
port)specify interactions points with
other parts
Connectors (shown if of interest) show
how parts are connected.
Ex: rear/front wheels (Power/Direction)
V hi l hi h
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SYS 5390 Lecture #2, Slide 44
Vehicle hierarchy
Block Definition Diagram
This diagram focuses on showing the decomposition of the Vehicle into its components
Indicates different usages of a
Wheelin the context of thePower train
Only one engine is part of a particularVehicle. They
represent a complete set of sub-classes and are
mutually exclusive or disjoint ({complete, disjoint}
constraint)
The Vehicle controller
software is allocated to theVehicle Processor.
The Vehicle Processoris the
execution platform for the
Vehicle Controllersoftware.
Components specification
(Interaction and interaction
analysis)
P id P
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SYS 5390 Lecture #2, Slide 45
Provide Power
Activity Diagram
The activity diagram Control Powershowed that the Vehicle must Provide Powerin
response to the Driver Accelerator Cmdand generate Wheel-Torque at the road surface.
The Provide Power activity diagram shows how the Vehicle components generate this
torque.
The actions in the activity partitions that are allocated to the Vehicle components realize the
provide poweraction that the Vehicle perform, as shown in the activity diagram Control Power.
This approach is used to decompose the system behavior.
External inputs
External
outputs
Nonstreaming input: only available prior the start of the action execution
Nonstreaming output: produced only at the completion of the action execution
Power subsys tem
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SYS 5390 Lecture #2, Slide 46
Power subsys tem
Internal Block Diagram
This diagram shows how the parts are interconnected to achieve the functionality previously described.
It is a structural view vs. the behavioral view expressed in the activity diagram.The diagram includes only
parts that collaborate withProvide Power
Frame is the Vehicle
Fuel stored
(store) Same approach for
provide breaking
provide steering
Left and right rear
are different usages
of the Wheelblock.
: is used todistinguish the part
(usage) from the
block (definition)
The expression to
the right is the
generic definition
The expression to
the left is the
particular usage
Other example : Fuel
Defining the Equations to Analyze
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SYS 5390 Lecture #2, Slide 47
Defining the Equations to Analyze
Vehicle Performance (1/2)
Critical requirements are for the design of this automobile To accelerate from 0 to 60 mph in less than 8 seconds
To achieve a fuel efficiency greater than 25 mpg
Two alternative solutions: 4 and 6-cylinder engines Alternatives shown in the Vehicle Hierarchybdd
Other impacts with different engines:
Vehicle weight Body shape
Electrical power
The Vehicle controller controls Fuel and air mixture
When the gear changes in the automatic transmission
to optimize engine and overall performance
Defining the Equations to Analyze
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SYS 5390 Lecture #2, Slide 48
Defining the Equations to Analyze
Vehicle Performance (2/2)
Block Definition Diagram forAnalysis Contextdefines the equations for analyzing the vehicle
acceleration requirement.
The equations and their parameters are specified using constraint blocks.
Constraint block defines:Parameters (with units)
Generic equations (if
definition not deferred to
detailed analysis)
Diagram also
referencesAutomobile
Domain:
Identify both the
equations for the
analysis and the subjectof the analysis
Equations can
constraint the
properties of the
Vehicle, its components
and the physical
environment.
Vehicle Ac celerat ion analysis
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SYS 5390 Lecture #2, Slide 49
Vehicle Ac celerat ionanalysis
Parametric Diagram
The Parametric Diagram shows how the equations are used to analyze the time for the
Vehicle to accelerate from 0 to 60 mph.
It shows a network of constraints (equations). Each constraint is a usage of a constraint blockdefined in the previous bdd
The diagram can then be exported to the appropriate simulation tools for property values
evaluation.Binding connector: Output
total force ft is equal to input f
in theAcceleration equation
Parameters can be bound toproperties of blocks:
it makes the parameter equal
to the property.
a.v.b = Bodyof the Vehicle of
the Autmobile Domain
Analysis Results from
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SYS 5390 Lecture #2, Slide 50
Analysis Results from
Vehicle Ac celerat ion
Results from Engineering analysis can then be incorporated into the SysML model, or using other
incorporated models.
Ex: UML timing diagram
Using the Vehicle Control ler
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SYS 5390 Lecture #2, Slide 51
Using the Vehicle Control ler
to Optimize Engine Performance
This activity diagram is a refinement of a portion of the Provide Poweractivity diagram
Vehicle Controller software has been added as an activity partition to support the analysis needed to
optimize fuel efficiency and engine performance
The specification of the algorithms require further analysis
A parametric diagram can specify the required fuel and air mixture in terms of RPM and engine
temperature to achieve optimum fuel efficiency, and they can be used to constrain the inputs and outputs
of the actions
The algorithms can be captured either in an activity diagram or directly in code
The Vehicle Controllerincludes
an action to Control Fuel Air
Mixture that produces the Engine
Acceleration Command.
The Vehicle Controllerincludes
an action to Control Gearto
determine when to change gear
based on engine speed (i.e.
RPM)
Specifying the Vehicle
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SYS 5390 Lecture #2, Slide 52
Specifying the Vehicle
and its components
The Block definition diagram Vehicle Structure defined the blocks for the Vehicle and its
components.
The preceding analysis was used to specify the features of the blocks in terms of
Functions they perform,
Interfaces
Performances
And physical properties.
Component example: 6-Cylinder Engine block
Selected properties are indicated along
with their units
The 6-Cylinder Engine performs a
function called generate torque, with
specified inputs and outputs
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SYS 5390 Lecture #2, Slide 53
Requirement traceability
Capturing theAutomobile System Requirements in the SysML model provides the means
to establish traceability between the requirements and other parts of the model
Example: Requirement for the Maximum Acceleration
Requirement is satisfied by the
Power Subsystem shown in its
own bdd
Rationale refers the
engineering analysisbased on the Vehicle
Acceleration Analysis
parametric diagram
Test case is shown as the
method to verify the requirement
is satisfied
Engine Powerrequirement
is derived from the
Maximum Acceleration req.
and contained in the
Engine Specification.
The 6-cylinder Engine block
refines the Engine Specification
by restating the requirements in
the model
Package Diagram
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Package Diagram
for Organizing the Model
Integrated system model is the fundamental concept of MBSE
The Model contains all of the model elements
The model elements and their relationships
are captured in a Model Repositery
And can be displayed on diagrams
Model elements on one diagram may have relationships to
model elements on other diagrams.
Thus, a model organization is essential to manage the model.
The Package diagram shows how the model elements are
organized into packages.
Each package contains a set of model elements.
Model elements in one package can be related to model
elements in another package
BUT, model organization enable each model element tobe uniquely identified by the package that contains it
View is generally similar to a tool browser.