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1Massachusetts Institute of Technology © Ed Crawley 2002
System ArchitectureAn Overview and Agenda
Ed CrawleyOli deWeck
Aeronautics and AstronauticsEngineering Systems
MIT
With inspiration from:Rechtin, Maier, Koopman, Hastings, Vetrivius
2Massachusetts Institute of Technology © Ed Crawley 2002
Today’s Topics
! Objectives and Opportunities! 6 Views and Definitions! Architecture Case! Research Agenda
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" To develop principles, methods andtools for system architecture synthesis,which:" Contain a holistic view" Represent emergence
" Insures the delivery of value" Have utility to real practitioners
Objectives
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Opportunities! Expressed need! Great leverage of architecture, and
even greater leverage of architectureprocess and tools
! Great room for improvement andaddition for rigor
! Opportunity for education andorganizational change
We have to build the intellectual foundationfor the field of System Architecture
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Progression of a Discipline
! Observation! Classification! Symbolic representation! Symbolic manipulation! Analysis! Synthesis
Where are we in System Architecture?
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Architecture - 6 Views
Principles
Methods &Tools
ThemesCasesFrameworksRoles &Definitions
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A Definition! Architecture
– The embodiment of concept, and the allocation ofphysical/informational function (process) toelements of form (objects) and definition ofstructural interfaces among the objects
! Consists of:– Function– Related by Concept– To Form
Form
Func
tion
Concept
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Architecture – Civil
ContemporaryBeach
Source - www.coolhouseplans.com
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Architecture – Mechanical
Suspension bridge
Cable-stayed bridge
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Architecture - Informational
Insert scanned image of cannon camera system
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A Tool - Object Process Modeling! Object: that which has the
potential of stable, unconditionalexistence for some positiveduration of time. Objects havestates.
! Form is the sum of objects! Process: the pattern of
transformation applied to one ormore objects. Processes changestates.
! Function emerges from processes! All links between objects and
processes have precisesemantics
Objects
Processes
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A Case - Refrigerator! It is essential for ground system architecture in
real world strength cases! Examine the flow of information through three
phases:– Reducing ambiguity*, by transforming a
statement of value to goals– Exercising creativity* by defining concept– Managing the evolution of complexity*
! * The three themes are pervasive in architecture
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Goals! Start by examining the
operand associatedwith value
! Next identify theattribute of the operandwhose change isassociated with value
! Next define thetransformation of theattribute associatedwith value, in solutionneutral form
This will reduce ambiguity and lead you to a valuefocused, solution neutral statement of goals on process
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Concept! Concept: a system
vision, which embodiesworking principles, amapping from functionto form
! Choose from among thesystem operatingprocessing thatspecialize to the desiredsolution neutral, valuerelated process
! Specialize the relatedgeneric concept to theproduct form
This is theexercise ofcreativity
Concept
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Decomposition of Function and Form
! Identify form of thewhole productsystem
! Zoom the processesof function
! Decompose the formof the product object
! Establish the objectprocess links
Establishing the complexity of the object-process architecture
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Framework - Precedence of Processes! Sub-processes which support the primary
externally-delivered process linked to value
! Other sub-processes linked to other necessaryexternally-delivered processes
! Interfacing processes
! Supporting/connecting processes
! Powering processes
! Controlling/regulating processes
! Normal operation processes
! Contingency/alternative operational processes
Then -
Then -
Then-
Then-
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Structure of the Form! Examine the
interactions impliedby thedecomposition ofform
Establishing the complexity of the object-object architecture
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Design vs. Architecture! Architecture selects the
concept, decomposition andmapping of form to function
! Architecture establishes thevector of design andoperating parameters
! Design selects of the valuesof the vector of parameters
! This is what optimization isgood for
! Some work in “architecture”is just an exhaustive searchover the design of onearchitecture
OperatingParameters
DesignParameters
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Decomposition of the Refrigerator
! More one to onecorrespondenceof objects andprocesses
! Note the wholeproduct elementssuppressed:– Food– Support structure– Heat load– Operator
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Structure of the Refrigerator
Considerably moreobject - objectcomplexity
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So Why Refrigerators and not Coolers?
! Refrigerators have significantly morecomplexity than coolers
! Refrigerators have more functions,performance and robustness thancoolers.
Principle: underlying and long enduringfundamentals that are always (or almostalways) valid.
Is a principle lurking here?
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Robust Functionality DrivesEssential Complexity
! Essential complexity is that which is essential to deliverfunctionality before gratuitous complexity slips in
! Functionality drives complexity in any given concept! But “Functionality” is often defined as a surrogate for a
much broader set of functions which the product willactually be use for.
! Therefore, it is the (often implicit) robust functionality whichdrives essential complexity
A Principle
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Architecture - 6 Views
Principles
Methods &Tools
ThemesCasesFrameworksRoles &Definitions
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Research Agenda! We must identify, codify and build the principles,
methods and tools of system architecture! These must follow the deployment and delivery of value
to the customer! To do this we must trace the flow of information through
the Product Development Process! The tools we develop must work for systems of real
complexity! They must also have utility to the real potential users.
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A New Research Partnership
University Research
Education
IndustryGov Labs
“Laboratory”
Lear
nersFlow-down
Results
Org.
Cha
nge
Critique
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Building Blocks! There are many disciplines upon which we can build
– Mech Eng. - Formal Design Theory– Management - System Dynamics, Options Theory– Control - Robust Hybrid Systems Theory– AI - Computational Design Theory– Mathematics - Topology, Graph Theory
! We must build on (and build something more usefulthan) Generalized System Theory of the 60’s
We must build the intellectual foundation for the fieldof System Architecture