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Product Architecture and Modularity
Systems EngineeringMG587
Karl T. Ulrich and Steven D. Eppinger3rd Edition, Irwin McGraw-Hill, 2004.
Product Architecture: DefinitionThe arrangement of functional elements into physical chunks which become the building blocks for the product or family of products.
Product
module
module
module
module
module
module
module
module
Other terms for “Chunks”
• A ‘Chunk’ is made up of a collection of components that carry out various functions/sub-functions of the product.
• Other terms for “Chunks” or elements that make up a chunk– Subsystem
– Cluster
– Module
– Building blocks
• ‘Interfaces’ connect these chunks together.
Architecture
• The Architecture of a product is the scheme by which the functional elements of the product are arranged into physical chunks and by which the chunks interact.
PlanningPlanning
Product Development Process
ConceptDevelopment
ConceptDevelopment
System-LevelDesign
System-LevelDesign
DetailDesign
DetailDesign
Testing andRefinement
Testing andRefinement
ProductionRamp-Up
ProductionRamp-Up
Product architecture is determined early in the development process.This is not a linear, sequential process.
Platform decision
Concept decision
Decomposition decision
Architecture Decisions
FunctionalElements
Interfaces
Modularity
Product Platform, Variety
Cost andManufactura
bility
Physical Elements
Product DevelopmentManagement
Architecture Decisions
Choosing the Product Architecture
Architecture decisions relate to product planning and concept development decisions:
– Product Change (copier toner, camera lenses)
– Product Variety (computers, automobiles)
– Standardization (motors, bearings, fasteners)
– Performance (racing bikes, fighter planes)
– Manufacturing Cost (disk drives, razors)
– Project Management (team capacity, skills)
How Does Architecture Happen?
• Ulrich and Eppinger – ‘Chunks’ approach.
• MIT – Design Structure Matrix.
• Buede – Decomposition,
– Physical mirrors Functional structures.
• Dominant Flow Heuristics - R. B. Stone
Architectures: Challenge X
Provide Transportation
Energy
Materials
Information
Transportation
Emissions
Modular or Integral Architecture?
Motorola StarTACCellular Phone
RollerbladeIn-Line Skates
FordExplorer
AppleiBook
Modular Product Architectures
• Chunks implement one or a few functions entirely.
• Interactions between chunks are well defined.• Modular architecture has advantages in
simplicity and reusability for a product family or platform.
Swiss Army Knife Sony Walkman
Trailer Example:Modular Architecture
box
hitch
fairing
bed
springs
wheels
protect cargofrom weather
connect to vehicle
minimizeair drag
supportcargo loads
suspendtrailer structure
transfer loadsto road
Trailer Example:Integral Architecture
upper half
lower half
nose piece
cargo hangingstraps
spring slotcovers
wheels
protect cargofrom weather
connect to vehicle
minimizeair drag
supportcargo loads
suspendtrailer structure
transfer loadsto road
Integral Product Architectures
• Functional elements are implemented by multiple chunks, or a chunk may implement many functions.
• Interactions between chunks are poorly defined.• Integral architecture generally increases
performance and reduces costs for any specific product model.
Compact Camera
Ford Taurus Integrated Control Panel
Discussion Question
• Is one type of product architecture (modular vs. integral) better than the other?– Performance– Platforms– Serviceability– Interfaces– Cost to manufacture– Cost to develop
Steps to Establish the Product Architecture – Ulrich and Eppinger
1. Create a functional model or schematic of the product.
2. Cluster the elements on the schematic.
3. Make Geometric Layouts to achieve the types of product variety.
4. Identify Interactions– Fundamental (must interact)– Incidental
Step 1: Functional or Schematic Diagram
• Physical and/or Functional
• Connect Elements Which Have Fundamental Interactions
• Show “Motion” & “Flow”
Example: Rapid Prototyping Machine using laser sintering
Step 2: Cluster Elements into Chunks
• Reasons to Cluster
– close geometric relationship
– function sharing– modular– desire to outsource
Atmospheric Control Unit
Laser Table
Powder Engine
Control Cabinet
Step 3: Produce Geometric Layout
Note: If you can’t make a geometrical layout then go back and redefine chunks and identify interactions
Step 4: Identify Interactions
• Forces consideration of geometric interfaces to accommodate flows
• Illustrates possible problems caused by interactions– Fundamental
• Lines on the schematic that connect chunks• Usually a well understood property
– Incidental• Usually not shown on schematic• Higher order effects/interferences
Product Architecture Example:Hewlett-Packard DeskJet Printer
Part of a portfolio architecture and is composed of parts within a product architecture
DeskJet Printer Schematic
Flow of forces or energy
Flow of material
Flow of signals or data
StoreOutput
StoreBlankPaper
EnclosePrinter
ProvideStructuralSupport
PrintCartridge
PositionCartridgeIn X-Axis
PositionPaper
In Y-Axis
SupplyDC
Power“Pick”Paper
ControlPrinter
CommandPrinter
Connectto
Host
CommunicatewithHost
DisplayStatus
AcceptUser
Inputs
Functionalor PhysicalElements
Cluster Elements into Chunks
StoreOutput
StoreBlankPaper
EnclosePrinter
ProvideStructuralSupport
PrintCartridge
PositionCartridgeIn X-Axis
PositionPaper
In Y-Axis
SupplyDC
Power“Pick”Paper
ControlPrinter
CommandPrinter
Connectto
Host
CommunicatewithHost
DisplayStatus
AcceptUser
Inputs
Paper Tray PrintMechanism
Logic Board
Chassis
Enclosure
User Interface Board
Host Driver
Software
Power Cordand “Brick”
Functionalor PhysicalElements
Chunks
Geometric Layout
printmechanism
paper tray
user interface board
printcartridge
logicboard
chassis
chassis
paper
roller
print cartridge
paper tray
enclosure
logic board
height
Incidental Interactions
Enclosure
Paper Tray
Chassis
PrintMechanism
User InterfaceBoard
LogicBoard
Power Cordand “Brick”
Host DriverSoftware
Styling
Vibration
Thermal Distortion
Thermal Distortion
RF InterferenceRF
Shielding
Dominant Flow Heuristics
• Heuristic 1: “The set of sub-functions through which a flow passes, from entry or initiation of the flow in the system to exit from the system or conversion of the flow within the system, define a module.”
Function
System
Energy
Material
Information
The Wok Example
Generic Dominant Flow Illustration
Interface
Interaction
Material
Energy
Dominant Flow Example
• Fragment of the iced tea brewer FM
import solid
store solid
filter, teasecuresolid
importsolid
storesolid
icesecuresolid
importhumanforce
human force
importelectricity
actuateelectricity
electricity regulateelectricity
convertelect. to
therm. ener.
transmittherm. ener.
transportliquid
exportliquid
regulategas-flow
mix solid& liquid
refineliquid
regulateliquid-flow
mix solid & liquid
store liquid
exportliquid
importliquid
transportliquid
waterstoreliquid
stopliquid-flow
human force
human force
human force
tea, filter
heat
ice
ice
brewed teaMaterial flow
Energy flow
Identifiedmodules
transportliquid
therm. ener.
filter, tea
filter, tea
h.f. h.f.
h.f. h.f.
ice ice
waterwater
water
water
h.f.
elect.elect.
water
water water
tea, filter
t.e. t.e. t.e.tea
tea
brewed tea
therm.ener.
therm.ener.
brewed tea
guide liquid
filter,usedtea
steamt.e.
dissipatetherm. ener.
senseposition
therm.ener.
alignmentaligned
Signal flow
brewed tea brewed
tea
brewed tea
t.e.
Branching Flow
• Heuristic 2: “Parallel function chains associated with a flow that branches constitute modules. Each of the modules interfaces with the remainder of the product through the flow at the branch.”
Generic Branching Flow Illustration
Interface
Material
Module/Chunk #1
Module/Chunk #2
Branch
Branching Flow Example
• Fragment of the iced tea brewer FM
import solid
store solid
filter, teasecuresolid
importsolid
storesolid
icesecuresolid
importhumanforce
human force
importelectricity
actuateelectricity
electricity regulateelectricity
convertelect. to
therm. ener.
transmittherm. ener.
transportliquid
exportliquid
regulategas-flow
mix solid& liquid
refineliquid
regulateliquid-flow
mix solid & liquid
store liquid
exportliquid
importliquid
transportliquid
waterstoreliquid
stopliquid-flow
human force
human force
human force
tea, filter
heat
ice
ice
brewed teaMaterial flow
Energy flow
Identifiedmodules
transportliquid
therm. ener.
filter, tea
filter, tea
h.f. h.f.
h.f. h.f.
ice ice
waterwater
water
water
h.f.
elect.elect.
water
water water
tea, filter
t.e. t.e. t.e.tea
tea
brewed tea
therm.ener.
therm.ener.
brewed tea
guide liquid
filter,usedtea
steamt.e.
dissipatetherm. ener.
senseposition
therm.ener.
alignmentaligned
Signal flow
brewed tea brewed
tea
brewed tea
t.e.
Conversion-Transmission Modules
• Heuristic 3: A conversion sub-function or a conversion-transmission pair or proper chain of sub-functions constitutes a module.
transmit(transport)
flow B
convert flow A to
flow B
function flow B
conversion-transmission chain
… …
Conversion-Transmission Example
• Fragment of the iced tea brewer FM
import solid
store solid
filter, teasecuresolid
importsolid
storesolid
icesecuresolid
importhumanforce
human force
importelectricity
actuateelectricity
electricity regulateelectricity
convertelect. to
therm. ener.
transmittherm. ener.
transportliquid
exportliquid
regulategas-flow
mix solid& liquid
refineliquid
regulateliquid-flow
mix solid & liquid
store liquid
exportliquid
importliquid
transportliquid
waterstoreliquid
stopliquid-flow
human force
human force
human force
tea, filter
heat
ice
ice
brewed teaMaterial flow
Energy flow
Identifiedmodules
transportliquid
therm. ener.
filter, tea
filter, tea
h.f. h.f.
h.f. h.f.
ice ice
waterwater
water
water
h.f.
elect.elect.
water
water water
tea, filter
t.e. t.e. t.e.tea
tea
brewed tea
therm.ener.
therm.ener.
brewed tea
guide liquid
filter,usedtea
steamt.e.
dissipatetherm. ener.
senseposition
therm.ener.
alignmentaligned
Signal flow
brewed tea brewed
tea
brewed tea
t.e.
The Design Structure Matrix (DSM):
An Information Exchange Method
Interpretation:• Task D requires information from tasks E, F, and L.• Task B transfers information to tasks C, F, G, J, and K.
Donald V. Steward, Aug. IEEE Trans. on Eng. Mgmt. 1981
Note:• Information flows are easier to capture than work flows.• Inputs are easier to capture than outputs.
DSM (Partitioned, or Sequenced)
Note:Manipulate the matrix to emphasize features of the process
flow.Sequential, parallel and coupled tasks can be identified.
ClusteringAlgorithms
System Team AssignmentBased on Product Architecture
F G E D I A C B1 K1 J P N Q R B2 K2 O L M H S T U V
Crankshaft F F l l l l l l l l l l l l
Flywheel G l G l l l l
Connecting Rods E l E l l l l l l
Pistons D l l l D l l l l l l l l lLubrication I l l l l I l l l l l l l l l
Engine Block A l l l l l A l l l l l l l l l l
Camshaft/Valve Train C l l l l C l l l l l l
Cylinder Heads B1 l l l l l B1 l l l l l lIntake Manifold K1 l l l l K1 l l l l l
Water Pump/Cooling J l l l l l l J l l l l l l l l l
Fuel System P l P l l l l l l l l l l
Air Cleaner N l N l l l l l lThrottle Body Q l l l Q l l l l l l l l l
EVAP R l l R l l l
Cylinder Heads B2 l l l B2 l l l l l l l lIntake Manifold K2 l l l l l l K2 l l l l l l l
A.I.R. O l l l l l l O l l l l l l
Exhaust L l l l l l l l l L l l l l l l
E.G.R. M l l l l l l l l M l l l l l
Accessory Drive H l l l l l l l l l l l l l l l l H l l l l
Ignition S l l l l l l l l l l l l l l l l S l l lE.C.M. T l l l l l l l l l l l l l l l l l l T l l
Electrical System U l l l l l l l l l l l l l l l l l l l U lEngine Assembly V l l l l l l l l l l l l l l l l l l l l l l V
Frequency of PDT Interactions
l Daily l Weekly l Monthly
Team 1
Team 2
Team 3
Team 4
Integration Team
From “Innovation at the Speed of Information”, S. Eppinger, HBR, January 2001.
Modularity
• Modularity is a product development strategy in which interfaces shared among components in a given product architecture become specified and standardized to allow for greater substitutability of components across product families.
Types of Modular Designs
• Slot
• Bus
• Sectional
• All retain a 1-to-1 mapping of functional to physical elements
Modular vs. Integral
• Modular • Integral
Example of Modularity
K. Ulrich, “The Role of Product Architecture in the Manufacturing Firm” Research Policy, 24, 419-440 (1995)
Example of Modularity
K. Ulrich, “The Role of Product Architecture in the Manufacturing Firm” Research Policy, 24, 419-440 (1995)
Example of Modularity
K. Ulrich, “The Role of Product Architecture in the Manufacturing Firm” Research Policy, 24, 419-440 (1995)
Sony Walkman
Product Model Lifetime
From Sanderson and Uzumeri, The Innovation Imperative, Irwin 1997.
0 1 2 3 4 5Survival Time (years)
1.0
0.8
0.6
0.4
0.2
0
FractionSurviving Sony
AIWAToshibaPanasonic
Sony1.97 yr
Others1.18 yr
Average Life
About 200 versions of the Sony Walkman from four platforms!
Platforms and Modularity
Some Modularity Benefits
• Production of a great variety of end products from a limited number of building blocks
• Platform strategy permitting many product variants based on a stable architecture
• Facilitate changes to current and future products
• Simplifies parallel testing
• Serviceability
• Allows for parallel development of design teams
• Allows for outsourcing
Some Limitations to Modularity
• Cannot discriminate look alike products
• Increases the risk of competitors copying designs
• Generally increases unit cost ( more components), volume (size) or weight of the product
• More interfaces are less reliable (why??)
• Depends on the capabilities of designers
Impact of Modularity Decisions on Later Design Processes
Product Architecture Example:Hewlett-Packard DeskJet Printer
Planning a Modular Product Line:Commonality Table
Differentiation versus Commonality
Trade off product variety and production complexity
Planning a Modular Product Line:Differentiation Table
Differentiation versus Commonality
Trade off product variety and production complexity
Supply Chain Issues of
Postponing Differentiation
Examples of Postponing Differentiation
• Paint in Hardware Store• Cake in Grocery Store• Your experiences….
Product Configurators
• Satisfy customer demand by creating a product composed of a number of pre-defined components
• Select and arrange parts to fit product and operational constraints
• Requirements:– Modularization– Custom assembly operations– Up-front engineering and testing
Fundamental Decisions
• Integral vs. modular architecture?• What type of modularity?• What type of interfaces?• How to assign functions to chunks?• How to assign chunks to teams?• Which chunks to outsource?
Product Architecture: Conclusions
• Architecture choices define the sub-systems and modules of the product platform or family.
• Architecture determines:– ease of production variety– feasibility of customer modification– system-level production costs
• Key Concepts:– modular vs. integral architecture– clustering into chunks– planning product families