Design of Worth for Consumer Product Development(<Special Issue>What is "What's the Design"?)

(1)

NII-Electronic Library Service

Design

of

Worth

for

ConsumerProductDevetopment

KolchiOHTOMI

CorporateR&DCenter,ToshibaCorporation

Abstract

WorthisassessedthrougheuttheLifeCycle.Thenwecon$ider atrade-off between Worth, _Cost,and TLme Thismethodology

isaconcerningselectionotdesignsolutionsfromthousandsot combinations of design_parameters.The current DesigntorX

(DfX>

isconsidered tobeextended, and so themethodology is calied Extended DfX.Here,thismethodology isapplied to

consumer _productdevelopment,Worthof consumer _products

isespecially important, butWorth isnot always equivalent to

performances,whereas itu$ually i$ inthe case of other

products.Therefore,anove1approachisrequiredforassessing

Worth

in

eonsumer _product

development

The

design

for

product

sound

_quality

isalso introducedas the another approachforthedesignofworth.

Keywords

DfX; worth; cost; time; cu$tomer; function, structure; PC ;trade-off;method ;tool, optimization ;Sound ;Sound quality, SQ metrics ;Noise; Multipleclassiticatfon analysis

,

Psychoacoustic

1.Introduction

The _processof_productdevelopment varies _greatlydepending ontheproductfield.Fig.1.showsanexampieofcla$sMcationof

the _product development _pattern.The axis of absassas

indicatesthesizeofthe _product

_development

_in

_proportion_to the development cost. The venical a)cisindicateswhether the objective

is

mass production

tor

an unspecified clientor productionordered bya speciftcclient,Powerplantand space equipment correspond tothelowernghtregion.Thisregiontsa

productfieldin which development cost is high and the

performancecan beinvestigated thoroughly overa long_pertod oftime.The consumer _productthatisthetargetof this_paperis antithetical to_power_plantand space equipment Thjsreg]on is a _productfieldinwhich investment in_productdevelopment is

relatively small and development time isshort. The _productof

thisreglon 1$customer-driven, Flg2.shows various methodst

toolsforthe_productdevelopment

_[1

_,

2].These methodsftools can be extensively used forthe above-mentioned _plantand

space equipment. On theother hand,it_isnecessary _toapply themselectivelyandefficientlyinthecaseofconsumerproduct development 1largetSh Sm Fig.1 CgpecdiedCustumcr} ProductclassifFcation Strategrc Fig2 Methodolog}' ale De$rgnMethodfToelMethodfTool Practicat

lnthis

_paper,

we

_propose

a designconcept forconsumer

product deve[opment, lnthe case of consumer _product

development,a customer hastheabilitytodecidethe_product

priceinmany cases. This cause$ a manutacturer tomake a

productthat has Iess variety. _As a result, a manufacture

endeavors to reduce costs by improvingeffictency and

becomes caught up [nprice-driven cempetition lnorder to

breakthiscycle,itisnecessary to assess Worth from the

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JapaneseSociety for the Science of Design

manufacturer's _pointofview and toreflecttheresult inproduct development. Many studies have attempted toeva[uate wortht

value from the customer's _pointof view

[3,

4].That is,a potentialcustomer requirement isanalyzed, and

_quanttfted

as absolute worth

(we

definethisas Worth)independentofcosL

Then, we estimate Costtorealize theabove-mentioned Worth byusingWo rthtFunctionfStructurerelation

_graph

_[5],

We detine thisconcept as ExtendedDfXmethodology, an exiension ofthe current DfX

_[6]

toWorth-based

_product

development.

The designfor_productsound _qualityisalso introduced a$the

another approach forthedesignof worth, This methodo[ogy

incorporates two evaluation methods. One is a sensory

evaluation method employing the semantic differential

(SD)

technique, whtch determines _{psychological}metrics tomeasure the[evelof_plea$antsound. The otherisa physicalevaluation method towhich Zwicker's sound _qualitymetrics analysis can

be

applied,which

determines

physicalmetrics to measure the levelof

_pleasant

sound,

map, a _groupof _productvarjeties can bevisualized. Then,the boundaryofthe lowestCost1imitand the highestWorthllmit come intoview. Thisboundary iscalled a Paretooptimal

solution.ProductsBand FinFig,3.correspond tothissolution Thatis,we can see agroup ofbestsolutions bymapping Cost and Worth on theWorthlCostmap

[ike

this.

_This

iswhy we

focuson Worth and compare

Worth

and Cost on an equal

tootlng.

We consider a trade-offbetween Worth and Cost,butwe may include _Time

_(schedule)

_inaddition teWorth and Cost,

Product B and product Fare optimal solution$ inthecurrent

state.The optimal solutiondoesnot always satisfy the target

solution. InthLscase, the reduction of Cost down and the increaseofWorthwj1Ibeneededinordertoapproachthetarget. Tab 1.ProductVarieties

ProductABcDEFGH Psrtaalalalaaa2a2a2a2 Partbbtblb2b2btblb2b2 Partccae2cac2cac2clc2 Worthxtx2xux4x5x6x7x8 Cestt2345678

32

2.

Trade-off

between

vvorth and cost

Here, forthe sake of simplictty, we consider a _product

composed of threeklndsof _parts:a,

b,

and c.Each ofthese partshastwo kindsof _grades

,

1and 2.Then,eight kinds ot productscan be considered inaccordance withthecube oftwo as shown inTab.1

.

Roughlyspeaking, thecost isdefinedas the

sum ofthecostofeach _partforeightkindsof products.On the

other hand,Worthatthecomponent 1evelincreases jfthe_grade ishigher,However,unlike inthecase of a CPU, Worthis not always proportionalto_priceThereare some nonlinear factors. Inaddition, _productWorth itselfisnot equal to the sum of component Worth.HarmonLousbalanceas the_product_greaUy

affects Worth.Inaddition, Worthstrongly

depends

on the user oftheproduct, when itisused, and where itisused.

We

assume that

Worth

ofeach oftheeight

kinds

ofproducts isobiained bysome means The result isplottedon the _Worthl Costmap as shown inFig3.IttherelatLonbetween Costand Worth is1inear,eight kindsof _pointsare _plottedon thestraight

lineHowever, $ince Worth isdefinedthrough a rather complex process,results willbescattered as shown inFtg.3,An actual

preduct consjsts ofdozens ofpartsand _grades Moreover,the

style,thecolor,weight, size, etc.should be considered for evaluatton ottherelation between Costand Worth Therefore, thousands of _productvaneties exist Once Cost and Worth for thousands of _productvarieties are _plottedon the Worth/Cost

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Worth

Fig.3WorthtCostMapforEightProducts 3. Extended DFX methodology

We

propose

Extended

DfXmethodology thatenhances the

DfX

desdgnprocedurefordigitalconsumer productdevelopment.

DtXisaphilosophyand practiceadvocated byGatenby otBell Laboratories,ofAT&T, in1990

_[6]

thatensure _quality_products and services, reduce the time tomarket fora _product,and

minlm-ze life-cyclecosts. That is,itLs a way ot evaluating various _problemsthroughoutthelifecycle atan earlystage ot productdevelopment as much as _possible,and decreasingthe

redesign inthelatterhalfof the_productdevelopment as much as _possibleln_practice,thedesign methodftooi shown jnFig,2.

issystematically applied according tothe DtX methodology. it

(3)

iscomparatively easy toapply the DtX methodo]ogy to

Iarge-scale _product development,butforconsumer _productsa more

concrete way offocusingon Worth isrequired. _So, the DfX

methodology isexpanded toincludethe

design

of

Worth

as shown LnFig,4.Worthissetfir$t,and Costisderivedthrough

functionaldesignand structuraldesign.Worth becomes the

targetforthecustomer and Costbecomes thetargetforthe manufacturer, thatis,thisisa trade-offbetween Worth and Cost.

Fig4.ConceptefExtended DfXMethoddogy

ln

general,

therelationbetweenWorthand Costismapped on theWorth!Cost_graphas shown inFig.5.An achievable area Ls obtained by trade-offanalysis, but

generally

neither an achievable area nor a _goalarea corresponds, Thisisakindof

trade-off,A trade-offanalysjs method thatuses GA has

recent]y been established and can be applaed. Thus, the problembecomes ciear by_plottingcurrent designen theWorthi

Cost _graph.For instance,the cooling method becomes a

problemwhen the _generatedheat _grows _by advancing CPU

(1)Targetsetting

on WorthtCostMap<2)MappmgachievahleareaunWorthiCostMap

performanceas shown inFig.6.innotebook PC design.Ifwe mtroduce a targe fansystem te remove the _generatedheat from notebook PC with high-performanceCPU, the entire PC

becomes

large,

and Worth forcustomer

decreases

overal].

Therefore,a technicalbreakthroughforheat relection is

required -moo Fig,5 osre>tse: Jer WorthVCestMap

Worth

Fig,6. otoU CPUPerformancc NeedforBreak-throughTechnology

(3)Mappmgrc-deslgn

Tesultgonprevious Worth!CostMap(4) Re-evaluate mitial

targetandmove target

teachievab]epomt on WortblCostMap Worth tzoU Worth ntao/t

tttx

Worth tioU Fig.7.ProcedureofExtendedDfX g Worth

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lmagh]gspeea Quiet Souiid HigliqLtHlity

'Noise

Lo]glife Rigidity ?ewercensttmption

Longtermusc

Funnt'o"mership {]nnvenic]icc Usabi]ity AffbrdHble Portability Reliable Expatidable Tpustworthy Ct]lor Goeddesiun Size "rcight Goodimage E¢e-fi'icndly Brandimage

Fig.8.Worth/FunctiontStructureRelation We explain theprocedure oftheextended DfX byreferring to Fig.7,Firstofali,thetargetisset on theWorth/Costmap. Thjsi$

atthe_p[anningstage. Forexample, PC with Worthequivalent

to

_$4000

lsdevelopedataCostof

$2000

forthe_powerPC user. Next,"Design

of Worth",'`Functional _design", and "Structura] design"are executed inaccordance with theDfXmethodology, Worth isobtained trom ''De$ign

of Worth'',

eo$tis

asse$sed trom`Design

ofthe structure", and, as a result,Worthand Cost

are plottedon _theWorthlCostmap. In_general,

because

_the

designachievable area doesn't satisfy thetargetat_thisstage,

we need toredesign toobtainnew Worthand Costclose tothe

targetbycontrollingdesign_parametersand designrestrictions. New Worthand Costare _plottedon the WorthtCostmap again,

This_procedureenable$ us toapproach the target.An initial

targetisre-evaluated when we

judge

thatthe achievement of

aninitialtargetisdifficult,andtheagreementpointofthedesign feasib[eregion and the designtarget i$$et. In_practice,thls

design process i$ executed by using the Worth/Functioni

Structurerelation _graphshown inFig.8.

4. Design for

_product

seund _quality

AIIthesounds _generatedby an operating _producthave been considered to be noise so far.Theretore, both users and

manufacturers have tendedto view a productwith a lower

noi$e levelas abetterproduct.However, sound isa keyfactor inKansetemotional information, whereas noise reductjon is

subiect to a Iimitation.The _productsound shou[d not be considered as a negative directionof noise buttreated as one

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Whatis'WhaL'stheDesign'? Speciallssueof}apaneseSode.±ytottheSciemcetiibeslgn voL16-2 na62 200g Structure cptj pttcmo.rv Graphicschip Display Hard disedrivc(HDD) Buttery CID,,DVD CooJjngsystem Cotnmunicationkit Interf'ace Keyboard l'ointimgdevicc I.oudspeHker Powersupply Chassis Metherboard Connccter OperHtingsystem(OS) Applicatiansoftwarc Customerservice Tndusttiuldesign

sound. Productworth can be enhanced by Improvingthe

product sound. That is,the targeted _product sound is

appropriate or not forthe customer, ifnot, how _torealizethe

appropriate _product sound. This approach is important

because itenables the manufacturer _toadd worth tothe

product,

The performanceand thesound

(noise)

ot theproductare

closely related jnthecase of home appliances. Forexamp]e, "collecting

garbage''

and "sound"

cannot be considered

separately inthecase ofavacuum cleaner. In

_product

sound desjgn,noi$e reductjontechniques havebeenexecuted mainly from the viewpoint of `'noise". _Moreover,

noise reduction

techniques have been applied to _productsthatare already completedtosomedegree.

Fig.9.shows thedesignnnethodoiogy for_productsounci by comparing the''as-i$i"

and the'to-be"

productsound definition.

Inthetraditionalapproach tonoise reduction, _productsound i$

treatedas noise thatshould beminimized as much as _possible, Moreover,because_periormanceisthefirst_priorityand noise reductjon isa secondary issue,countermeasures to reduce noise are usually implementedatter _prototyping,Thus,the productworth _generatedisdeterminedbythedecreaseofa

negatjveimpression.

On the other hand, inthe design tor_productsound _quaiity,

the _productsound istreated as $ound thatadd$ worth tothe

product.Therefore,the customer's _preferenceinterm$ of

sound isdefinedand a strategy torealize thisisrequired. The worth realized bythisapproach can endow theproduct with an

(5)

NII-Electronic Library Service attributethat_givesa _positiveimpressiontotheuser,However,

forthispurpose,itisneces$ary toembrace theview that`fthe productsound isnotanoise" and themetricsfordesigningthe sound atthe

_product

designstage shou1d bedefined.

The conventional

_product

development_processisshown in

Fig.10,The new ideaforthe next _productisdecided by

analyzing thesensory evaluatlon and the evaluation ot sound qua[itymetrjcs. Inthiscase, thesensory evaluation and the evaluation of sound _qualitymetrics are _performedseparately.

Forthe next _productembodying the new idea, the sound

evaluation can be_performedafterprototyping, When thesound afterprototyping isunsatistactory, countermeasures $hould be

implementodwithinthetimeandcostcon$traints.

On theother hand,the designfor

_product

sound _quality determinesthemetrics for_productsound, considerjng boththe

sensoty evaluation and theevaluation ofsound _qualitymetrics, Thetargetsound forthenext _productisdeterminedaccording

tothemetrics forproductsound. Asthetargetsound i$defined physically,thiscanbeproducedvirtuallybyadigitalsoundtoel. Therefore,the sound evaluation forthe next _productcan be performedbeforeprototyping.Next,the _pFoductsound

design

is _performed to realize the target sound, considering

performanceetc, Fjnally,a _productwith excellent _periormance andsoundcanberealized,

Fig.11.shows the_procedureofthe_desjgnfor_productsound quality.Itisnecessary to define two metrics to_perform the

productsound de$ign.First,an impressionevaluation is

performedby sensory analysis toevaluate thecustomer's

impressionof the targeted _productsound. Inthe impres$ion

evaluation, targetcustomers listentothetargeted sound. Then,

t"

etttt -g:.te "-' _setet,-l.

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causes

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[ voL16-? no.6? 2009

(6)

the VoC

_(Voice

of Customer) revealing potential needs

concerning _the sound isanalyzed by the SD

(semantic

differentiabmethod andlor the method ot _pairedcomparison,

etc,The results are transformedintothemetric$ for_product

sound bymultipleclassificationanalysis, The metrics obtained bytheimpressionevaluation isdefinedas the _{psychological} metrics here.

The _{psychological}metrics isimportantfor_quantifyinghow thecustomer]s impressionofthetargeted sound.

However,

itis difficulttocombine thetargeted sound withthesound design only on thebasisof the psychologicalmetrics. Itisa[so necessary toexpress thetargetedsound _physicallybymeans

ofan objective eva]uatjon. As measurable design_parameters of the

_product

sound, we use fourbasicSQ

(Sound

Quality)

metrics

_[7]

: loudness,sharpness, roughness, and fluctuation strength. The$e are widely used and well detjned.

These basicmetrics are not always defined_physicallybut derivedthrough many $ensory evaluations. These

SQ

metrics

can beapplied directlytotheobjective evaluation, butas the number ofSQ metrics isratherbig,itisnecessary todefinea

new metrics using these _SQ metrics. Moreover,itisnotable

thatsome productsounds cannot be definedby theseSQ

metrics. 1nthiscase, we should definethenew metrics forthe

principle

of the _physicalmeaning. The metrics obtained bythe physjcaleva[uationisdefinedasthephysicalmetricshere.

Generally,the _{psychological}metrics isused forsound

design. However, because the target$ound isnot expressed

numerically

(physical

metrics), itisdifficulttodesign _product

sound directlyfrom the _{psychorogical}metrics.

So,

the psychologicalmetrics should be reflected inthe design of productsound through the_physicalmetrics.

For

this_purpose,

therelation betweenthe_{psychological}metrics andthe _physical

metrics should be defined. This relation isthe metrics for productsound. Afterdetiningthemetrics for_productsound, the

target _productsound isset,The targetsound set inthe psychologica[domainismapped intothe_physicaldomain,The targetsound mapped inthe_physica]domain isnot unique.

Finally,the target sound isdetermined,considering the

easiness of realization etc. Thistarget sound becomes a specification of the design tor _productsound qualitythat achievestheworthyseund.

5.

Application

ofdesign

for

_product

sound

quality

The application ot the _designfor_productsound

_quality

toa vacuum cleaner isintroduced.A vacuum cleaner makes a

continuous sound duringoperation. The _productsound is

classified intocontinuous sounds, discontinuoussounds, unexpected sounds, etc. Continuoussounds are common and fundamentaltothe _productsound. Inthe case of vacuum

cleaner sound design,we weuld _pursue"sounds _like vacuum

cieanerf', `fee]ing

of ]uxury",and "$ounds _heard

sottiY'.

Our

target forvacuum cleaner sound jsthe jnclusion of these ambiguous requirements inthe _productdevelopment. This paperpresentsthefir$tsteptowardrealizingthattarget,

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Here,

thesensory evaluation,thephysical evaluation, and

the mapping between sensory evaluation and sound _quality

rnetricsare_performedforthesounds of1OmodeIs.

Fig.12.showstheapplicationofthedesignforproductsound

qualitytoavacuum cleaner.The design_processisdividedinto two_parts:`'sensory

evaluation'' and "physical

evaluation". The stationary sounds from 10 selected models of different manufacturers are reco rded inan anechoic chamber and used as evaluation samples.

Inthesensory evaluation, 22 examinees listen_tothesounds

of the tO models, The SD

(semantic

differential)method i$

applied toresponses consisting of25 pairsofadjectives

(16

pairsof genera[adjective$ and 9 pairs of product-specific adjectives).When theSD method jsapplied tothe sensory

evaluation,itisimportanttoselect a _pairof adject[ves carefully, First,thetargetwas clarifiedand thena_pairofadjectives tobe extracted isse]ected.

The22examinees aredividedintofour_groupsand seated in frontofa speaker. Each sound is_playedforfiveseconds and the examinees _give their impressionsot the sound

by

completing a _{questionnaire}consisting ofadjective _pairs.Two

tria]sof the same experiment are conducted totestthe reliabilityof the data.To avoid the influence of the learning

curve, the examinees _practiceresponding betore the

experimentisperformed.

The multiple classification analysis jsapplied tothevalue of 25 _pairsof adjectives

(mean

value of 22examinees) forthe

sound$ trom 1O models. Asa result,the

_principal

components

shown on the[eftinFig.12.are obtained. Here,the _primary

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Fig,13.show$ the relation between the _physica[and

psychologicalmetrics based on Fig.12.We call thisrelation "sound

measure forvacuum cleanerf'.

This

figure

means that the smaller the _{psychological}metrics,thebetterthe sound

quality

by

the sensory evaluation ot 22 examinees, The

physicalmetrics _for_thesounds from 1Omodels are widely

scattered. The sounds thatexistinthe vicjnity on thisfigure have similar sound

_qualjty.

The

_physjcal

metrics isrelated directlytothesounddesign,

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Fig,13.Relationbetween physical&psychoeogicalmetricsforsetting

oftargetsound&finalproductsound

Next,thetargetsound isset interms of the_physicalmetrics. Fig.13.also shows the_procedureot the targetsound settlng.

ModelsH,D,and C are bythe same manufacturer and the

designhas been improved inthisorder. The conventional productdevelopmentresults inthe jmprovement ofthe_product

sound.The targetsound issetbased on thecurrentmodel Cas

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Xl:Loudness X2:Sharpness X3:Roughness X4:Fluctuationstrength

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Psychological metrics = O,47*Physicalmetrics 1

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O.5'Physicalmetrics 2

Fig.12.

u-Applicationofdesignforproductsoundqualitytovacuumcleaner

ma

1 _{fif-f;.yenfikEF.--what/s'What'stheDesign'O} $pe:iallssueof]apaneseSocFetvfoFtheSclenceofDeslgn vol,16-2po.622009 NII-Electronic Mbra37y

(8)

38

shown inFig.13.Thisfigurealso shows the results forthe prototypeand the final_product.The sound forthe _prototype

satisfies thetargetsound, butthe sound forthetinal_productis set

based

on a con$ideration oftheauditoryevaluation ofthe prototype.Inorder to realize the target sound, the newly deve[opedsupporting system and theabsorbing _procedureare

app[ied,

6.Future

_prospects

tordesigntor_productsound _quality

Designisan importantelement of

_product

development

_[8].

On the other hand,the designgreatlydepends on the designer's abiMies and standardization isinsufficient.Itistherefore

necessary to clarify what the requirements are at the design stage inorder todevelopa_productstrategically and efficientiy.

The design for_productsound _qualityisone of the best

examples ottop-down design.Lyonmentions theimportanceof the design for_productsound _quaiity

[9],

and also refers _the

difficulty

of reailzing _that,_The _diffjcultycomes from the

quantificationof the ambiguous customer's needs. The

physicalevaluation can be done by fourbasicSQ

_(Sound

Quality)metrics, but these metrics cannot be applied to

discontinuoussounds such as a copier sound. The _physical

metrlcs todefinediscontinuoussounds shou]d bedevelopedto

extend applicable

_products

forthedesigntor_productsound quality.Alotoftechnicalissuesexist forrealizing thedesignfor

productsound _quality,but the most seFious _problem is

innovations of the _productdevelopment environment. Itis

importanthow to change the designphilosophyto lead

innovations[10].

7.Conclusjon

lnthispaper,featuresotconsumer product designwere first describedfromtheperspectiveofthedesignofWorth.Next,we

introducedthe Exiended DfX methodology toenhance DfX

(Design

forX)thatwas already established forconsumer products.We also introduceda practicalexample oftrade-off analysis and thesatisfying designthatisthekeytechnology

when Extended DtX isapplied. Moreover,the designfor

product sound _quaMy isalso introducedas the another

approachtorthedesignofworth.

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