INTERNATIONAL CONFERENCE ON ENGINEERING DESIGN ICED 03 STOCKHOLM, AUGUST 19-21, 2003 EVALUATION OF SOFT REQUIREMENTS DURING PRODUCT DESIGN

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1 INTERNATIONAL CONFERENCE ON ENGINEERING DESIGN ICED 3 STOCKHOLM, AUGUST 9-, 3 EVALUATION OF SOFT REQUIREMENTS DURING PRODUCT DESIGN Kjell Anderon Abtract Ti paper preent an approac to improve current metod for dealing wit cutomer requirement tat are of a more qualitative nature tan i common today. In addition, an approac to upport andling of qualitative meaure and to develop an evaluation metod tat can upport dealing wit tee totally different kind of demand i propoed. Ti metod will enable a kind of multi-criteria evaluation wit criteria coming from bot tecnical and aetetic iue. A firt approac a been baed on utilizing idea from value analyi a a bai for ti evaluation. Keyword: deign, evaluation metod, multi-criteria. Introduction Te global marketplace and an increaed competition ave forced indutry to become more efficient in development of new product. Flexibility and cutomer adaptation a become ome of te leading trategie in order to tay in te forefront of tecnical development today. Conumer oriented product, but alo oter type of product, a to an increaed degree ued tyling and uer adaptation a a way to gain competitive advantage. Ti mean tat indutrial deigner ave been ued in te project team, to give ti aetetic appearance and product identity. For new revolutionary product te new tecnical poibilitie enabled by a tecnical breaktroug i often enoug for a ucceful product launc. At ti time te company a a tecnical advantage by being te firt to bring te product on te market. For te next generation of te product te tecnical performance may not be ufficient to guarantee a ucceful product launc ince te competitor are now on te track and ave inveted a lot of money and man-time in learning te new tecnique. An often-ued approac i to involve indutrial deigner in parallel wit te tecnical development to improve te overall performance and uability of te product. Combining indutrial deign and engineering in te product development team i not eay and tere are many iue tat ave to be conidered. One main obtacle ere tat a to be tackled i ow to deal wit contradictory demand concerning tecnical performance and aetetic oft demand. Many of te oft, indutrial deign related, product propertie are not eaily meaurable or captured and expreed in engineering parameter.

2 . Background Te metod preented in ti paper i a reult from te Denni project []. In ti project we are uing a reearc metod, wic i baed on a combination of empirical tudie of indutrial deigner in Sweden and teoretical tudie of metod and tecnique for a upport metod. Te empirical tudie are performed bot a quetionnaire and interview of indutrial deigner. Te collaborative work of indutrial deigner and engineer in integrated product development team i alo tudied, in te companie participating in te project. Alo, te metod of interview of repreentative cutomer in focu group, on teir opinion of product prototype variant concerning uer interface and oter oft propertie, will be tudied, a a mean for gatering information on oft product propertie. For te pyical modelling of product variant and mock-up, computer baed tecnique like Rapid Prototyping i conidered. So far te quetionnaire and interview ave not been fully analyed and evaluated. Te finding preented in ti paper are baed on a combination of teoretical tudie of metod and tudie of collaborative work of indutrial deigner and engineer in integrated product development team. Te indutrial deigner i penetrating a company in dept wen an old product i to be given a new ape or wen a new product or product identity will be developed. Ti involvement by te indutrial deigner often concern emotional apect witin te producing company. It i ten important tat bot part can ave a mutual repect and undertanding for eac oter competence. We ave to create an undertanding of different way of tinking and addreing problem tak and to find metod for ow to utilie bot competence in te bet way. Concept Software Contractor Increaing company age Increaing degree of deign Detailed ketc Surface modelling program Roug ketc Fotoop ketc Model workop Surface modelling module in CAD CADCAM Figure. Workflow of a product definition project een from te indutrial deigner point of view [].

3 A tudy of te workflow of a product definition project een from te indutrial deigner point of view ave been made by []. Ti tudy a been performed in term of viit and dicuion wit te producing companie Scania AB and Saab Sytem and Electronic AB and te indutrial deign companie ErgonomiDeign AB, HotSwap and No Picnic. Te workflow i illutrated in figure, were ome of te major difference are noted concerning te age of te indutrial deign company a well a concerning te degree of deign in te product to be developed. Anoter intereting ti to notice i te different deciion point tat occur wen ometing i preented to te contractor for input or to erve a a bae for a deciion. It i alo at tee point tat an evaluation metod can be beneficial. 3. Approac Te purpoe of ti approac i to allow boot ard tecnical demand to be evaluated togeter wit oft demand in a more complete decription of te product concept to be evaluated. Te approac preented in ti paper i baed on tree main aumption:. We can divide cutomer demand into two main categorie.. We can ue QFD a a mean to illutrate relation between oft demand and deign parameter a well a between ard requirement and deign parameter. 3. We can apply idea from value analyi for judging cutomer demand. To tart wit, diviion of te cutomer demand into ard and oft one give a firt idea of wat difficultie we ave to olve ince it o obviou tat it ard to treat tee demand in a uniform way. Some example on wat tee different group of demand can conit of are given in table. Table. Example of ard and oft demand Hard demand Max velocity Max acceleration Noie level Payload (weigt, volume) Service friendly Soft demand Color Sape Sound caracter Product identity Ergonomic - Biomecanic - Antropometric - Perception Service interval Energy conumption Life time Size/Batc Environment Hygienic Te workflow i ten, for eac cutomer requirement, to invetigate wat relation it a to te lited deign parameter and to judge ow trong ti relation i, e.g. a number,3 or 9 correponding to a low, medium or trong relation. In ti way we

4 can aure tat alo te oft requirement a been accounted for in te development of te requirement pecification. We till ave te problem to quantify te oft deign parameter tat are related to tee type of cutomer requirement in te matrix. Some kind of qualitative value given by repreentative cutomer can probably be te bet way of dealing wit tee parameter. Deign. param. Cutomer req. Weigt Cutomer evaluation Hard demand Soft demand Tecnical bencmarking Figure. Te oue of quality adapted for dealing wit oft demand. Evaluation of oft requirement a well a for ard requirement will take place continuouly during te wole development proce. In oppoite to te ard requirement, wic can be tranformed into quantitative meaure, we mut be able to andle qualitative meaure for te oft requirement. Tee qualitative meaure can be of different kind depending on in wic pae of te development proce tat we are in. For early etimation and evaluation of a concept color and ape, e.g. 3D CAD model can be ued to create a number of propoal tat can be own for a repreentative cutomer group (focu group). In later tage, pyical prototype of different kind are preferable, e.g. clay model, FFF-model, wic alo are preented to a focu group a a number of concept variant. It i alo important tat tee prototype can be ued for evaluating product function in a number of typical uer equence. We need a imilar diviion of deign parameter into ard and oft parameter. We alo need to define wat demand tat are mandatory and cannot be omitted. Ti definition i made in te requirement pecification for te product. Te proce of etabliing te requirement pecification will not be dicued any furter. I only

5 want to point out tat te deign parameter in te QFD cart i ued a bai for ti proce. It i alo important to point out tat te evaluation metod decribed later can only be applied on toe concept tat fulfill all mandatory demand. Te baic idea wit te evaluation metod (illutrated in figure 3) i tat all olution are of equal weigt concerning ard and oft demand in te beginning. Baed on te tructure of cutomer demand made in te QFD cart a value analyi diviion i performed and te demand are aigned different core, ee figure 3. Tee aignment of core are made by te development team and can be een a a balance to te weigting made by te cutomer. Hard demand Soft demand Figure 3. Illutration of value analyi applied on te tructure of ard and oft demand. Te cutomer wen evaluating different concept propoal ould aign a tird rating core. Depending on in wic pae te project i in te development different media are ued to preent concept to te cutomer, e figure. Te cale to be ued can e.g. be integer, -3, were tand for not applicable and 3 for te bet concept wit repect to te actual criteria. Te total core, S for a concept can ten be expreed a: S = n i= C V J + m i= C V J Were: C = Cutomer weigting of ard demand V = Value analyi weigting of ard demand J = Cutomer judging of ard demand n = number of ard demand C = Cutomer weigting of oft demand V = Value analyi weigting of oft demand J = Cutomer judging of oft demand m = number of oft demand Eq.

6 4. Example: Deign of a bicycle A a mean to illutrate te idea wit te preented approac, I will ue te deign of a bicycle a an example. Firt of all I tart wit te aumption tat we ave made a market analyi and invetigated wat major demand tat te cutomer ave on a bicycle to be ued in terrain and on lippery trail. Figure 4. Example of bicycle from Skeppult, Sweden. Te reult of ti market analyi will reult in a QFD matrix were oft and ard demand are lited at te left ide togeter wit te correponding cutomer weigt factor. Tee demand are ten tranlated into deign parameter and te procee of developing concept olution take place. Here we will focu on te andling of oft and ard demand and ow tee can be ued for evaluating a concept wit te propoed metod. Terefore we are focuing olely on te ard and oft demand wit correponding cutomer weigt factor a own in table. Table C Hard demand C Soft demand Number of gear Ergonomic andle 4 Eay gearift 4 Ergonomic addle 3 Low weigt 5 Riding joy 3 Adjut damper 3 Cool Long Life 3 Nice Next I imply calculate te core for a fictive concept wit te propoed metod. In ti example te evaluation wit ti metod will reult in a total numerical value for te total core of te concept. It i alo important to tre te idea of te metod to erve a a mean to gater and preent te evaluation information for te project team opefully coniting of bot indutrial deigner and engineer. For a number of concept of different poible bicycle tat fulfil te mandatory demand of te requirement pecification we own and teted by a repreentative cutomer group. Tee concept were ten judged according to te earlier decribed cale from -3, were 3 i te top core. Te cutomer judgement togeter wit te value analyi rating by te deign team for one of tee concept i own in figure 5.

7 Hard demand Soft demand No. of gear Low weigt Adjut. damper Long life Ergonomic andle Eay gearift Ergonomic addle Riding joy Cool Nice Concept C V Concept C V J J 3 Figure 5. Illutration of te different core for a bicycle concept Te total core for ti concept calculated wit te equation; S = n i= C give S =.8 V J + m i= C V J 5. Concluion In current product development, te product tecnical performance can often be een a a contraint i.e. neceary requirement to be met. Te product oft requirement related to indutrial deign, e.g. uer interface, ergonomic, aetetic, and product emiotic, will ten be deciive for te cutomer. Te propoed metod to evaluate te oft propertie, a well a for aement of oft requirement and tranlation of tee into engineering pecification will ten repreent an important generic contribution to te product development proce. Ti metod alo aim to upport engineer to tudy trade-off between iue related to indutrial deign and iue related to more traditional product development. In addition will alo erve a a communication media between te indutrial deigner and te ret of te product development team. Furter development of te metod include dealing wit a more compreenive example a well a alternative way to preent te total core, e.g. uing ome kind of ymbol intead. Reference [] [] K. Anderon, J-G. Peron, T. Kjellberg, P. Joanon, KTH, T.Enlund, O. Scmidt, Kontfack, L. Svengren, H. Rynnel, SU, L. Avellán, B. Holmer, IVF. Produktframtagning för deign- oc nicamället krav DENNIS. Slutrapport del. Stockolm, Oktober [3] J-G. Peron, Produktframtagning för deign- oc nicamället krav Nytt Forkningprojekt, Mekaniten :4, Journal of te Swedi Society for Mecanical Engineer, Naval Arcitect and Aeronautical Engineer, Stockolm Dec.

8 Kjell Anderon, Royal Intitute of Tecnology, KTH, Dept of Macine Deign, SE- 44 Stockolm Tel: Int , Fax: Int , kan@md.kt.e