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System ArchitectureAn Overview and Agenda

Ed CrawleyOli deWeck

Aeronautics and AstronauticsEngineering Systems

MIT

With inspiration from:Rechtin, Maier, Koopman, Hastings, Vetrivius

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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