-1-

VIRTUAL CONCEPTS AND EXPERIMENTS TO IMPROVE QUALITY OF TRAIN INTERIORS

Antonio Lanzotti, Giuseppe Di Gironimo, Giovanna Matrone, Stanislao Patalano, Fabrizio Renno

University of Naples Federico II Piazzale Tecchio 80 - 80125 Napoli - Italy

Phone/Fax +39 081 768 2506 / 2187 E-mail : antonio.lanzotti@unina.it

Abstract: The paper aims at providing a methodological contribution to the concept design of train interior in order to improve the quality perceived by users in compliance with railway standards. Indeed, the combined use of advanced CAD tools, experimental statistical methods and Virtual Reality tools allows developing, selecting and experimentally evaluating new concepts.

The design cycle starts both from designers’ proposal and the identification of user’s needs; then, it makes use of datum-based CAD models in order to generate virtual concepts that satisfy railway standards; the cycle proceeds with the immersive evaluation of virtual prototypes, performed by potential and expert users in Virtual Reality. The identification of the optimal concept closes the design process. This procedure can be iterated in order to improve the quality of railway seats, evaluated thanks to the user’s involvement in the design cycle.

In this work a case study on a regional train is presented, developed at the Virtual Reality laboratory, named “VRTest”, of the Regional Centre for the qualification of transportation systems set up by Campania Regional Authority.

Key words: Concept Design, Kano Methodology, CAD Models, Design for Quality, Virtual Reality.

1 - Introduction

The use of a participatory design strategy to develop new usable interfaces of consumer products is successful [1]. On the other hand, for the development of transportation vectors, like trains, a participatory design strategy is not really applied. In the traditional train development process, in fact, styling and engineering activities are usually separated. The first one is based on designer creativity and does not directly involve the users. The second one is mainly based on the technical specifications of the tender, in respect of design constraints defined in railway international standards. A participatory design strategy could be helpful at the early stage of the product design cycle to identify pleasant product features (i.e. Quality Elements, QEs). A successful key is the

use of effective methods, as QFD [2], Kano Model [3] or Kansei Engineering [4]. Further, if the design team chooses to work with participatory design strategies and/or with methods for eliciting customer’s needs [5], then the users can only interact with sketches or 3D CAD models. For this reason, some strategies to evaluate product features in Virtual Reality environments are recently proposed [6]. The design team can plan virtual experiments adopting Design of Experiments (DOE) techniques in order to systematically generate concepts and to analyze the influence of different factors (QEs) on product appearance and usability performances [7, 8]. After the generation of concepts, it is possible to involve again expert users to evaluate the concepts through virtual interactive experiments and to choose the optimal one. These users can cooperate with designers to verify the esthetical, ergonomic and usable properties of concepts, thanks to the interaction with virtual prototypes in an immersive environment. In order to reduce the distance between styling and engineering, some advanced CAD tools may be used to improve the early development of concepts, in accomplishment to railway standards. The CAD models, in fact, can be modelled using a top-down approach based both on datum elements and functional links [9]. The functional links associated to datum elements allow improving the generation of concepts complying with standards and design constraints. A set of product-oriented modelling guidelines, executed through a parametric CAD system, is also presented in [10]. Advanced CAD tools and Virtual Reality technologies are also used in the re-design of a railway locomotive according to ergonomic requirements [11]. So, a challenge for competition among railway companies would be to combine different tools, in participative design strategies, to satisfy user needs according to standards and design constraints. The aim of this paper is to show the possibility of improving product quality, for systems subjected to strict standards and constraints, through the use of statistical methodologies, advanced CAD tools and Virtual Reality technologies. This approach has been applied to the design of railway seats on regional trains.

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-2-

2 - Virtual Concepts and Experiments strategy

Starting from [12], the proposed strategy of participatory design consists of six phases [Fig. 1] customized for systems subject to strong constraints:

I) Definition of Style II) Identification and Classification of Quality Elements III) Implementation of the Standards IV) Generation of Product Concepts V) Evaluation of Product Concepts VI) Definition of the Optimal Concepts

In the Definition of Style phase, the designer plays a pivot role in order to research shapes and colours that can be

Figure 1: The six phases of the proposed participatory concept design strategy.

pleasant for users. The designer chooses some key-words that give an idea of the product architecture. This proposal can suggest the style, for each part, that has to be developed in the following generation of product concepts phase. In the Identification and Classification of Quality Elements phase, the user plays a pivot role to identify the main product features [6] according to the Kano Model. In order to select the product features connected with user’s needs the design team

listens the Voice of the Customer [13] through direct web-based interviews and the reference to trade magazines or scientific journals. Starting from these information the most significant product features, from the user point of view, are selected and classified in quality categories according to the Kano Model. The product features classified as Must-be, One Dimensional or Attractive with the highest importance scores define the Quality Elements (QEs) on which the design team will work in the generation of product concepts phase. In the Implementation of the Standards phase, railway standards can be implemented in a knowledge-based design environment. In this way the concepts can be generated and modelled in virtual environment accordingly to the standards. This phase is very useful because of in many industrial fields, particularly in the transport one, industrial products are subject to strong standards. So it is often very hard to manage these technical requirements at the early stage of product development process. In the Generation of Product Concepts phase, the synthesis of the previous ones is realised; all contributions from designers, users and standards, are gathered to generate the product concepts. DOE (Design of Experiments) techniques are applied to define new product architectures. The design team fixes a design of experiments for the selected QEs. Then, it generates the number of alternative design solution accordingly to the number of levels planned into the chosen design of experiments. The new concepts for each QE are developed in the CAD environment according to the standards and following the style defined by designers. In the Evaluation of Product Concepts phase, the optimal level for each QE and the optimal concept among those previously generated are evaluated. The design team has to involve users to have a feedback from them about the fulfilment of their needs. The activity in this phase consists of an evaluation session of product concepts performed in Virtual Reality environment. Here, the user can interact with the product and live an experience of product use restricted to some senses. In the Definition of the Optimal Concepts phase, the design team can generate the optimal expected concepts on the base of the answers given by expert users involved and interviewed in the evaluation session. A confirmatory test to verify the results is needed. If the final data do not satisfy designers, they can apply the proposed strategy again, looking for new design solutions, in a continuous innovation loop that stats again from style definition and identification of Quality Elements.

3 – The quality improvement of train interiors

The effectiveness of the proposed strategy is tested by applying it to the design of new railway seats for a regional train. The study is led at the University of Naples Federico II and at the Virtual Reality laboratory, named “VRTest”, of the Centre of Competence for Transport Systems of the Campania Region in collaboration with Firema Trasporti S.p.A., an Italian railway construction company.

3.1 – International Standards for train interior design

The identification of the standards and the implementation of

III. Implementation of the Standards

STRUCTURE OF DATUM ELEMENTS

I. Definition of Style

CREATIVITY

II. Identification and Classification of QE

KANO MODEL

IV. Generation of Product Concepts

DOE - CAD

V. Evaluation of Product Concepts

VRLAB

VI. Definition of the Optimal Concepts

CONFIRMATORY TEST

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-3-

the geometric and ergonomic constraints in the design are mandatory to obtain adequate virtual concepts. By means of the standards, in fact, it is possible to define the technical requirements of the seats and the dimensional rules. In Table 1 are listed the main standards available for the railway design and production.

Denomination Description

FS 306572 Stuffing of the seats, couches, couchettes and beds of Italian FS roadways

FS 307202 Decorative Textile Coatings

FS 306930 Metallic products for roadways furniture

FS 308212 Seats for railway vehicles FS 308484 Internal Coatings CEI EN 50122-1 Measures for electric safety

UNI CEI 11170-1,2,3 Guidelines for the protection from fire of the railway vehicles

NF F 31-119 Behaviour of the seats under static and fatigue solicitations

UIC 566 OR Loadings of coach bodies and their components

UIC 567 OR Railway vehicles mounting

Table 1: Some standards for railway vehicle design and development In particular, the Trenitalia FS308212 standard (Seats for railway vehicles), used for the passenger seats, and the international UIC 567 OR standard (Railway vehicles mounting), for the railway coaches, are analyzed. According to them, the following guidelines are considered. A railway seat has to be comfortable and integrated with the railway environment. It has to assure an ergonomic posture and it has not to be harmful for the passenger. The backrest has to be high enough to sustain the body, the neck and the head. For this reasons it has to present the headrest, the armrests and the lateral supports of the headrest. However, to avoid disturbs like cramps or tingling to the passenger it is needed to ensure space enough aimed to easily change posture. Therefore, it is important to predispose a suitable area for the feet in order to avoid obstacle during the sit and the rise. In particular, in Table 2 the dimensional and geometrical constraints recommended by the standard FS308212 and UIC 567 OR are presented.

Distance between the

ground and the sitting plane 400 mm

Depth of the sitting 500 mm Width of the sitting 500 mm

Backrest Perpendicular to the sitting plane with lumbar support to the shape of the spine

Height of the backrest 980-1005 mm Height of the

lumbar support 200 mm

Distance between the backrest of the seats 980-1005 mm

Table 2: Technical requirements of the railway seats according to

standards FS308212 and UIC 567 OR.

4 - Definition of style

The first step of the proposed participatory design strategy is the definition of the style. In the analysed case study, three different ideas are presented. Inspired by the history of style in the railway field and by the rapid transformations in technological field, the style designers develop three different style solutions named “Yesterday”, “Today” and “Tomorrow”, respectively [Fig. 2]. The choice to turn attention to the past is due to the thought that innovation sometimes runs more than people can really understand. So, people can prefer to look at the past more than a far future. “Yesterday” is based on an ancient style and reproduces the typical environment of a steam engine but with higher comforts. “Today” reflects the present tendencies characterized by dynamism and functionality. So, in this style, the aesthetics is similar to the one now in use on trains or busses. “Tomorrow” is distinguished by futuristic shapes, by hi-tech materials, and the possibility of imagining a new idea of travel.

(a) (b)

(c)

Figure 2: Some drafts concerning the styles named “Yesterday” (a), “Today” (b) and “Tomorrow” (c).

5 – Identification and Classification of Quality Elements

The Kano Model [3] is applied to identify and classify the user’s needs. It is an effective method that allows designers to stratify product features in quality categories, according to the user’s viewpoint. The power of this method is to connect, in a very easily understandable way, the user’s needs with new or desirable product features. The first step is the identification of all those product features necessary for the definition and characterization of seats in a train. This phase is critical because it is important looking for all the possible sources of information. To this purpose a lot of direct interviews, researches on the net and trade journals are led. At the end, among all the identified features, the members of design team select fifteen main features on the

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-4-

basis of their experience:

1. coat stands 2. armrests 3. sober colours 4. direct lighting 5. handles 6. wastepaper baskets 7. footrests 8. plastic materials 9. headrests 10. air nozzles 11. sockets 12. lively colours 13. seat feed / back inclination systems 14. tip-top tables 15. wadded materials

Then, according to Kano Model [14], a questionnaire is drafted in three sections. The first one is aimed to a demographic analysis; the second one is aimed to the classification of the fifteen features in quality categories and, the third one, to fix the importance rating of features [Appendix A]. The questionnaire is sent by email to a group of potential users, between twenty and sixty-five years old. Indeed, the users of a regional train have different “characteristics” as, for example, age and travel motivations. In nearly two weeks 37 questionnaires are gathered and the answers are catalogued on a demographic principle, to emphasize the opinions of users who mainly use regional trains. The data results are analyzed through the Kano Evaluation Table and the identification of the quality categories for each product element is made according to the frequency of answers. In order to select the main quality elements two criterions are adopted: – to take into account Must-be, One-dimensional and Attractive elements and to reject the elements classified as Indifferent, Reverse or Skeptical; – to choose all those elements with an importance score higher than 6. Table 3 shows the quality elements selected, in compliance with the adopted criterions, among the starting fifteen product elements.

Elements Category Significance Rating

armrests O 7,9 seats moving systems M 7,5

air nozzles M 7,4 tip-top table O 7,2

footrests O 7,1 sockets O 6,6

direct lighting M 6,1

Table 3: Kano Classification, Quality Categories and Significance Rating.

Analysing these elements the design team choose do not take into account other three elements for the following reasons: – the air nozzles element cannot be modelled with the seat because, even if it is placed in the neighbourhood of seats, it belongs to the air conditioned system and is subjected to other

constraints; – the seat feed/back inclination systems is an adjustment element, and its quality is a performance that cannot be evaluated through a static experience in virtual environment without the use of a physical adjustable mock-up and other simulation devices; – the importance of the element sockets does not depend on aesthetics of the seat neighbourhood but it can be located also elsewhere. So, the chosen Quality Elements (QE) are: armrests, direct lighting, footrests and tip-top tables. These QEs are used by the members of design team to model many design solutions of railway seats.

6 – Implementation of the Standards

The standards considered in par. 3.1 are implemented and characterized in a set of virtual prototypes by means of a CAD software (NX3 by Siemens - UGS), using a top-down approach [15]. First, the structure of datum elements for the parts and the assemblies of the virtual prototypes of the seats for the three styles is defined. The construction of proper datum elements (points, axes, planes and sketched curves) and the use of the WAVE-Geometry Linker allow to realize and to modify the features that characterize hierarchically the assembly making easier the update of the complete structure. The structure of datum elements was defined starting from the railway standards showed in Table 4.

Denomination Type Description Ground Plane Horizontal Planes Plane coincident with the

railway wagon floor

Bolster Plane Horizontal Planes Plane coincident with the top surface of the fixing system of the seat

Plane A Min Horizontal Planes Inferior limit of the height of the seat

Plane A Max Horizontal Planes Plane A Max: superior limit of the height of the seat

Mirror Plane

Vertical Planes parallel to the XZ plane of the absolute reference system

Symmetry plane of the assembly coincident with the XZ plane of the absolute reference system

Right Bolster

Vertical Planes parallel to the XZ plane of the absolute reference system

Plane used for the "Today" model. It represents the limit of the right bolster of the seat fixing system to the floor. The position of this plane depends on the stress analyses performed on the structure

Right Armrest

Vertical Planes parallel to the XZ plane of the absolute reference system

Plane positioned at the middle of the right armrest

Left Bolster

Vertical Planes parallel to the XZ plane of the absolute reference system

Plane symmetric to the previously described two planes respect to the mirror plane

Left Armrest

Vertical Planes parallel to the XZ plane of the absolute reference system

Plane symmetric to the previously described two planes respect to the mirror plane

Point B Plane

Vertical Planes parallel to the YZ plane of the absolute reference system

Limit plane for the bolster of the lumbar section

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-5-

Point H Plane

Vertical Planes parallel to the YZ plane of the absolute reference system

Plane parallel to the Point B Plane

Point A Plane

Vertical Planes parallel to the YZ plane of the absolute reference system

It is used to control the max depth of the seat (according to “UIC 567 OR - Annexed 4.1 e 4.2” regulations must be equal or superior to 430 mm)

Table 4: Datum elements defined starting from the standards FS308212 and UIC 567 OR.

In particular, the standards FS308212 and UIC 567 OR allow to define twelve reference planes: a) four horizontal planes, and b) eight vertical planes, two of them containing the main sketched profiles [Fig. 3]. Datum elements control the main parameters of the prototypes as the height, the width, the depth of the seat and the dimensions of the backrest and of the armrests.

Plane A Min

Plane A Max

Mirror Plane

Bolster Plane

Right Armrest

Point B Plane Point H Plane

Right Bolster

Left Bolster

Left Armrest

Ground Plane

Point A Plane

Plane A Min

Plane A Max

Mirror Plane

Bolster Plane

Right Armrest

Point B Plane Point H Plane

Right Bolster

Left Bolster

Left Armrest

Ground Plane

Point A Plane

Figure 3: Structure of datum elements

for the CAD modelling of the seats.

After the realization of the structure of the datum elements, it is possible to define the sketches and the features according to the standards. Figure 4 shows a preliminary virtual prototype obtained starting from the sketches of the main features of the seat built on the mirror and right armrest planes. In Figure 5 some sketches usable for the definition of the datum points and of the profiles, needed for the construction of CAD models of the seat, are showed and, in particular, they are positioned on the Mirror Plane. All the elements of these sketches (except for the D and E points) have one degree of freedom to allow to modify the profile of the seat. For example, it is possible to change the height of the seat varying the position of the A point. The dimensions are defined according to the standard UIC 567 OR. The recommended distance between the backrests of the seats, able to assure a suitable space for the legs of the passenger, is set to 940 mm. Similarly, the distance between the B and the 0 points that represents the depth of the sitting is set to 430 mm (the standard suggests that it can vary in the 410 and 530 mm range), the backrest has to be perpendicular to the sitting plane and its height of the back can vary in the 980-1005 mm range.

Mirror PlaneRight Armrest Plane

Mirror PlaneRight Armrest Plane

Figure 4 – Example of some sketches built

on the datum planes defined in Figure 3. Therefore, sketches in Figure 5 define the limits of the bolster and of the headrest. The A’ point is the intersection between the Point A Plane and the A Min Plane (the height and the minimum depth of the bolster). The double chain lines represent the tracks of some of the planes defined in Figure 3.

A

A’

Ground Plane

B

C

E

D

0

X

X’•• ••

•

•

•

•

•

820600

Point B Plane

Point A Plane

400

Point H Plane18

0

Plane A Max

Plane A Min

Bolster limit

Headrest limit

A

A’

Ground Plane

B

C

E

D

0

X

X’•• ••

•

•

•

•

•

820600

Point B Plane

Point A Plane

400

Point H Plane18

0

Plane A Max

Plane A Min

Bolster limit

Headrest limit

Figure 5: Sketches on Mirror plane needed for the

construction of the models of the seat, the bolster and the base.

7 – Generation of Product Concepts

The generation of product concepts is performed through Factorization and Combination Methods based on Design of Experiments [7], [8]. The choice of the experimental design begins from the number of identified QEs, that is equal to four. So, each QE is considered as a factor and, for each of them, two levels are selected. The choice of only two levels is due to the conceptual nature of first stages in product development

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-6-

process, when designers are interested in discovering the optimal design to satisfy customer’s needs. Starting from four factors with two levels, a full factorial design is characterized by 24= 16 runs. Nevertheless, a full factorial design used for three different seats imply a high number of product concepts (16×3=48). So, to pursue an effective strategy of experimentation, the design team chooses to work with a lower number of runs for each style. For this reason a fractionated factorial design with 24-1= 8 runs is used [Tab. 5].

FACTOR Prototype A B C D

I –1 –1 –1 +1 II –1 –1 +1 –1 III –1 +1 –1 –1 IV –1 +1 +1 +1 V +1 –1 –1 –1 VI +1 –1 +1 +1 VII +1 +1 –1 +1 VII +1 +1 +1 –1

Table 5: Fractionated factorial design 24-1 used for experimentation.

After selecting the experimental design, for each QE two alternative design solutions are supposed as levels, according both to tenders and design team experience. In this way, four factors are defined with two levels codified with -1 and +1, respectively [Tab. 6].

LEVEL FACTOR -1 (low) +1 (high)Armrests Fixed Moving

Direct lighting Rear LateralFootrests No Yes

Tip-top table No Yes

Table 6: Factors and levels for virtual experiments.

Firstly, a “basic model” is modelled for each style. Then each QE, according to the corresponding level, is added to the basic model [Tab. 7]. This task is made possible using the structure of datum elements, carried out for each concept. For example, the CAD model of one of the QE, the right footrest, consists of several parts: a) two supports with two tracks on the sides of the hollow realized under the sitting plane, b) a pinion, c) a cylindrical bar, d) a pedal and a no slip rug. The position of the footrest is defined by some of the planes of Figure 3. In particular, Figure 6 shows the dimensions usable for the realization of the rectangular sketch (blue line) on the Point B Plane needed for the positioning of the footrest. In fact, the maximum length of the rectangular hollow is defined by the distance between the Mirror and the Right Armrest Planes, i.e. the width of the sitting (500 mm). The maximum height is defined by the distance between the ground and the bolster planes (400 mm). Starting from the sketch on the Point B Plane the limits of the asymmetric cut-out feature are the Point A Plane and the backside of the seat.

The footrest is designed to be moved to assume different positions along two guides that are symmetric to the Footrest Middle Plane shown in Figure 7.

500

Mirror PlanePoint B Plane

400

500

Right Armrest Plane

Bolster Plane

Point A Plane

500

Mirror PlanePoint B Plane

400

500

Right Armrest Plane

Bolster Plane

Point A Plane

Figure 6 - Datum planes, limit dimensions and sketches used for

the realization of the hollow needed for footrest positioning.

Mirror Plane

Ground Plane

Footreast Middle PlaneMirro

r Plane

Ground Plane

Footreast Middle Plane

Figure 7 – CAD model of the right footrest (one of the QE).

Two sliding bars are mounted on the tracks to realize the translation of the pedal. Therefore, there is a cylindrical bar located on the bottom plane of the pedal to allow small rotation of it. The translation is obtained by means of a rack coupled with the pinion. The CAD model of the pinion is a revolution feature characterized by the gear teeth (obtained by means of a circular array of the profile of the teeth). The main element of the footrest is the pedal that is a parallelepiped with 10mm rounds. Therefore, it has four rectangular arrays of an elliptical extrusion feature realized on the top face of the pedal to create a no slip rug. Finally, the CAD model of left footrest is obtained using the WAVE-Geometry Linker tool with a mirroring feature respect to the Mirror Plane.

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-7-

Factor A B C D

QEs Armrests Direct lighting Footrests Tip-top table

- 1

Absent Absent

Yes

terd

ay

+1

- 1

Absent Absent

Toda

y

+1

- 1

Absent Absent

Tom

orro

w

+1

Table 7: Virtual concepts of QEs chosen as design factors at two levels.

7.1 – “Yesterday” virtual concept

The basic model for “Yesterday” style [Fig. 8 (a)] is made up of a single structure with fasteners to floor, the basement and the back. Moreover, there are comfortable cushions that cover the seat. The 3D CAD model of the concept n.6 [Fig. 8 (b)] has armrests characterized by two fixed lateral parts and one moving central part. The lighting systems have the shape of fifties table lamps; the footrests are in wood covered with anti-slip rubber and they can be moved under the anterior seat.

7.2 – “Today” virtual concept

The basic model for “Today” style [Fig. 9 (a)] is characterised by the possibility to change back inclination and to modify the seat base position. The fastener system consists of two lateral supports tightened through tie plates. There is also a handle on

side corridor. The 3D CAD model of the concept n.6 [Fig. 9 (b)], for example, has the following characteristics: the armrests are simple and they can be easily moved; the lighting systems are large to allow a big lighting area on the tip-top tables; the footrests are joined with a central pin to the anterior seat.

7.3 – “Tomorrow” virtual concept

In “Tomorrow” style [Fig. 10 (a)] an innovative system is implemented to orient the seats in the same direction of train. Indeed this system allows the seats to rotate for 180°. The structure is characterized by a single body placed on a central support able to rotate. The single body consists of the base, the back and the headrest. Moreover, handles placed on both sides facilitate the rotation. For example, in the 3D CAD model of the concept n.6 [Fig. 10 (b)] the armrests are simple

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-8-

and they can be easily moved; the lighting systems are small but able to light all the area on the tip-top tables; the footrests are joined to the anterior seat with an innovative systems of armrests.

(a)

(b)

Figure 8: (a) 3D CAD basic model and (b) concept n.6 for the “Yesterday” style.

(a)

(b)

Figure 9: (a) 3D CAD basic model and (b) concept n.6 for the “Today” style.

8 – Evaluation of Product Concepts

Finally, the product concepts are evaluated in Virtual Reality environment to identify the optimal concept for each style and, then, to analyze the results comparing the three style. For this reason, the concepts previously modelled in 3D CAD environment, are transferred in Virtual Reality using vrcom Virtual Design 2® software. Moreover they are enriched with lights and textures to augment the realism of visualization. A

virtual prototype of a regional train previously developed is chosen as background to contextualize the new seat concepts [Fig. 11].

(a)

(b)

Figure 10: (a) 3D CAD basic model and (b) concept n.6 for the “Tomorrow” style.

Figure 11: The virtual train for the “Today” style.

An evaluation session is performed at the Virtual Reality laboratory VRTest. There, two groups of expert/potential users, respectively engaged in style and engineering activities, are involved; the first one is composed of seven postgraduates attending the Master “Product Design” of University of L’Aquila and the second one is composed of fifteen students enrolled at the Faculty of Industrial Design of the Second University of Naples. They are asked to compile a satisfaction questionnaire through a Likert scale from 1 (totally unsatisfied) to 10 (totally satisfied); this way they can express their opinion about the proposed concepts in terms of goodness, effectiveness, comfort and aesthetics [Fig. 12].

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-9-

Figure 12: The evaluation session at the VRTest. For each style the eight concepts are showed adopting real size for seats and using random sequence to reduce possible noise effects due to the order of presentation. Moreover the same navigation way is used for each concept in order to equally highlight the QEs. In particular, for each evaluation three points of sight are used. These points are related to different positions assumed by the users. The users are standing up in the coach entrance [Figure 13] or they are walking along the coach corridor [Figure 14] or they are seated on the railway seat [Figure 15].

Figure 13: Point of view of the user standing up in the coach entrance (Yesterday virtual concept).

Figure 14: Point of view of the user walking

along the coach corridor (Today virtual concept).

Figure 15: Point of view of the seated user

(Tomorrow virtual concept).

9 – Definition of the Optimal Concepts

In order to identify the optimal concepts according to the user judgment, the data results from questionnaires of the evaluation session are analyzed through the Pareto Anova [Tab. 8] and the mean effects analysis [Tab. 10]. In this way the significant factors are recognized and, then, their expected optimal combination is identified.

0

0

0

0

0

0

ay 4,19 4,924,76 5,64

ow 4,52 5,19

C - C +

y 4,69 4,424,92 5,48

w 5,13 4,58

B - B +3,50

4,00

4,50

5,00

5,50

6,00

Yesterday 4,26 4,85

Today 5,11 5,28

Tomorrow 4,75 4,96

A - A +

3,92 5,194,67 5,734,42 5,29

D - D +

Table 10: Main Effect Plots for each QE and each style.

The meaningful factors are the QEs Footrests and Tip-top table; indeed they maximize, at their high level, the perceived quality whatever the style. For this reason the development cycle will carry on with the implementation of these two

elements. According to the Pareto Anova, whereby the meaningful factors are the ones whose cumulative contribution ratio gets to 90%, the QE Armrests result not significant for the style

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-10-

“Today”, whilst the QE Direct lighting result not significant for the style “Yesterday”. So, in the definition of the expected optimal concepts, these last two QEs are chosen at the level selected by designers on the basis of their experience.

Style Pareto Anova Expected Optimal

Concept D C A B Yesterday 63% 20% 14% 3% A+B–C+D+

D C B A Today 50% 35% 14% 1% A–B+C+D+

D C B A Tomorrow 49% 29% 19% 3% A–B–C+D+

Table 8: Results from Pareto Anova and expected optimal concepts.

At the end, a confirmatory test is performed for each style in order to verify the expected results in homogeneous conditions. The fifteen students enrolled at the Faculty of Industrial Design of the Second University of Naples previously mentioned, are involved again as exert/potential users. The comparison among the first data results (Experimental optimal concept) and those of the confirmatory test (Expected optimal concept) [Figure 16] show that for each style there is an increase of the mean value, more or less strong.

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

Expe

rimen

tal V

S Ex

pect

ed

Experimental 5,73 6,09 6,05Espected 7,08 6,92 6,08

Yesterday Today Tomorrow

Figure 16: Comparison between the experimental optimal concepts (Yellow) and expected optimal concept (Red).

Nevertheless, to assess the best style for the users it is useful to carry out an hypothesis test. Indeed, even if the higher mean value is for the “Yesterday” style, the variability of the data around this value did not give the certainty to assure that style as the best one.

t α t(α;ν) Difference Yesterday

Today 0,27 0,10 1,36 Not Significant

Yesterday Tomorrow 1,59 0,10 1,36 Significant

Today Tomorrow 1,52 0,10 1,36 Significant

Table 9: Results from the Student test.

So a one-tailed Student’s test is performed [16] for the differences between the mean value measured for the expected optimal concept of each style and the mean value for the expected optimal concept of all other styles [Tab. 9]. Table 9 shows that the difference between “Yesterday” and “Today” styles are not statistically significant even with a high risk of 10% (α=0,10) while the other two differences are significant for a high risk level (α=0,10) but not for a risk of 5%. These results show that, in this case, statistics did not go to help designers to discriminate between the two styles “Yesterday” and “Today” to elect the best one [Figure 17]. The evaluation about the optimal style to develop for the train interior will be taken by the design team in the following steps of design process and starting from the briefing with the design of the train exterior.

Figure 17: The expected optimal concepts for “Yesterday” and “Today” style, respectively.

10 - Conclusions

In this paper a participatory design strategy is presented to improve the quality of new train interiors involving users in key phases of concept design process. This strategy has three main aims: – to reduce the actual separation between the style and engineering activities; – to involve potential users since first stages of product development process both in the identification of new features and in their evaluation; – to support the design team in the management of design constraints that are defined by international standards. The capacity of this strategy is to promote the combined use of different tools and methods for the design of products with strict constraints, also with the support of advanced IT systems as virtual reality environments.

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-11-

The case study, concerning railway seats, shows the possibility of developing product concepts in compliance with standards constraints and, at the same time, that improve users’ satisfaction. The virtual experiments show a significant quality increment of the final concepts if compared with the initial ones. Further, this strategy helps the design team to choose the style and the product features more pleasant for the users. If the final quality do not satisfy design team, it is possible to apply the proposed strategy again, looking for new design solutions, in a continuous innovation loop.

11 - Acknowledgments

The present paper was developed with the economic support of MIUR, performing the activities of PRIN 2006 project: “PUODARSI: Product User-Oriented Development based on Augmented Reality and interactive SImulation” and of the project “Test X Transport”, Law 297/1999 Art. 12/lab, DM 23175. The authors deeply thank Firema Trasporti SpA for the knowledge of international standards on “Railway Seats” and “Coach Arrangements” and engineers Alejandro Cadarso, in his Erasmus project from the University of Vigo, Stefano Papa and Andrea Tarallo at VR Test Lab for the indispensable technical support.

12 - References

[1] Sanoff, H.: (ed) Special issue on participatory design, Design Studies, 28(3): 213-214 (2007) [2] Akao, Y.: Development History of Quality Function Deployment , The Customer Driven Approach to Quality Planning and Deployment. Minato, Tokyo 107 Japan: Asian Productivity Organization, 339 (1994). ISBN 92-833-1121-3. [3] Kano, N. et al.: Attractive Quality and Must-be Quality. Hinshitsu, The Journal of the Japanese Society for Quality Control, 14(2):39-48 (1984) [4] Nagamachi M. (2008), Perspectives and the new trend of Kansei /affective engineering, The TQM Journal, Emerald Group Publishing Limited, Vol. 20, 4, 290 – 298, DOI: 10.1108/17542730810881285. [5] Chen, C., Chuang, M.: Integrating the Kano model into a robust design approach to enhance customer satisfaction with product design, Int. J. Production Economics, 114:667– 681 (2008) [6] Lanzotti, A., Matrone, G., Tarantino, P., Vanacore, A.: Statistical Design for Innovation in Virtual Reality. In Erto, P. (2008) "Statistics for Innovation", Springer, ISBN 978-88-470-0814-4 (2008). [7] Otto, K., Wood K., Product Design, Prentice Hall, (2001) [8] Shah, J.: Experimental Investigation of Progressive Idea Generation Technique in Engineering Design, CD-ROM Proc. of the ASME DETC'98, paper no. DETC98/DTM-5676, Sept. 13-16, Atlanta, GA, 1998. [9] Mosca, F., Di Martino, C., Aleixos, N.: Complex CAD project management by means of designing criteria control tools. Deployment of a vehicle gearbox archetype with the aid of Wave by Unigraphics. CD-ROM Proceed. of XII ADM International Conference, Rimini, Italy - Sept. 5th-7th (2001)

[10] Aleixos, N., Company, P., Contero M.: Integrated modeling with top-down approach in subsidiary industries. Computers in Industry, 53(1): 97-116, ISSN 0166-3615 (2004) [11] Di Gironimo, G., Patalano, S.: Re-design of a railway locomotive in virtual environment for ergonomic requirements. International Journal of Interactive Design and Manufacturing, 2:47–57, DOI 10.1007/s12008-007-0035-z (2008) [12] Di Gironimo, G., Lanzotti, A, Vanacore, A.: Concept Design for Quality in Virtual Environment. Computers & Graphics, 30(6):1011-1019, ISSN: 0097-8493 (2006) [13] Griffin, A., Hauser, J. R.: The Voice of the Customer. Marketing Science, 12(1):1-27 (1993) [14] Berger, C. et al.: Kano’s Method for Understanding Customer-defined Quality. The Center for Quality Management Journal, 2(4) (1993) [15] Patalano, S., Renno, F.: CAD Modelling of Complex Shape Products: Planning and Development of a Gearbox Model, CD-ROM Proceedings of the 6th IPMM Conference, Salerno, Italy, 25-29 June (2007) [16] Erto, P.: Probabilità e statistica per le scienze e l’ingegneria, (in Italian) 3th ed., McGraw-Hill (2008)

Virtual Concepts and Experiments to Improve Quality of Train Interiors

-12-

13 - Appendix A

KANO’S QUESTIONNAIRE This is a questionnaire developed according to the Kano Model in the ambit of a concept design of railway seats for regional trains. The objective is to study the impact of the seat’ features on the customer satisfaction.

SECTION 1 – DEMOGRAPHIC This part of the questionnaire contains some demographic questions about the interviewed. Please mark the alternatives which better describe your situation: 1.1 GENDER 1.2 AGES 1.3 PROFESSION 1.4 How many times in a month you catch the train? 1.5 For which reason you catch the train? 1.6 What kind of train you use? SECTION 2 ― REQUIREMENTS OF THE USER In this part of the questionnaire for each seats feature there are two questions about both the presence and absence of them. It is requested to consider each question individually and to mark the options that better describe your experience. Please only mark one option for each question.

2.1 a. If there is a coat-rack nears the seat how would you feel? 2.1 b. If there is not a coat-rack nears the seat how would you feel? 2.2 a. If there are armrests between the seats how would you feel? 2.2 b. If there are not armrests between the seats how would you feel? 2.3 a. If are used sober colors how would you feel? 2.3 b. If are not used sober colors how would you feel? 2.4 a. If there is a system of direct illumination how would you feel? 2.4 b. If there is not a system of direct illumination how would you feel? 2.5 a. If there are handles on the corridor side how would you feel? 2.5 b. If there are not handles on the corridor side how would you feel? 2.6 a. If there is a shelf with a wastebasket how would you feel? 2.6 b. If there is not a shelf with a wastebasket how would you feel? 2.7 a. If there is a support for your feet how would you feel? 2.7 b. If there is not a support for your feet how would you feel? 2.8 a. If the armrests are modeled in plastic material how would you feel? 2.8 b. If the armrests are not modeled in plastic material how would you feel? 2.9 a. If the headrests are endowed with earmuffs how would you feel? 2.9 b. If the headrests are not endowed with earmuffs how would you feel?

2.10 a If the nozzles position of the air conditioning are such that they didn't create direct flows how would you feel? 2.10 b. If the nozzles position of the air conditioning are not such that they didn't create direct flows how would you feel? 2.11 a. If there are electric plugs for each seat how would you feel? 2.11 b. If there are not electric plugs for each seat how would you feel? 2.12 a. If are used alive colors how would you feel? 2.12 b. If are not used alive colors how would you feel? 2.13 a. If there is a system of seat advancement and backrest inclination how would you feel? 2.13 b. If there is not a system of seat advancement and backrest inclination how would you feel? 2.14 a. If there are folding tables how would you feel? 2.14 b. If there are not folding tables how would you feel? 2.15 a. If the armrests are lined how would you feel? 2.15 b. If the armrests are not lined how would you feel?

SECTION 3 ― SELF STATED IMPORTANCE QUESTIONNAIRE In this section of the questionnaire there are questions about the importance of the different features previously specified. This importance is measured in a scale from 1 to 10, where 1 means nothing important and 10 that it is really important.

3.1 How such important is for you the presence of the coat-racks near the seat? 3.2 How such important is for you the presence of the armrests between the seats? 3.3 How such important is for you the use of sober colors? 3.4 How such important is for you the presence of a system of direct illumination? 3.5 How such important is for you the presence of handles on the corridor side? 3.6 How such important is for you the presence a shelf with a wastebasket? 3.7 How such important is for you the presence of support for your feet? 3.8 How such important is for you that the armrests were modeled in plastic material? 3.9 How such important is for you that the headrests were endowed with earmuffs? 3.10 How such important is for you that the nozzles position of the air conditioning is such that doesn’t create direct flows? 3.11 How such important is for you having a electric plug near your seat? 3.12 How such important is for you the use of alive colors? 3.13 How such important is for you the presence of a system of seat advancement and backrest inclination? 3.14 How such important is for you the presence of folding tables? 3.15 How such important is for you that the armrests were lined?