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