Intuitive and objective processes in automotive design

Intuitive and objective processes in automotive design Michael Tovey, School of Art and Design, Coventry Polytechnic, Gosford Street, Coventry CV1 5AZ, UK

The characteristics and specialist responsibilities which distinguish industrial designers from engineering designers are most strongly evident in the automobile industry. Car stylists use intuitive processes, and private form and graphic languages. Design managers control the styling process through a number of management intervention points which provide a precise objective framework for the process. If conventional processes are to be computerized then any system must both permit the intuitive processes and fit into the management's objective framework.

oventry Polytechnic's research project 'Computer-aided vehicle styling' funded by the Science and Engineering Research Council is concerned with the processes and procedures used by automotive stylists and how they might be modified, using CAD systems. It has the aim of not only devising procedures by which CAD systems can be integrated into stylists activities, but also that of producing a specification for a dedicated system suitable for use by automotive stylists. In this paper I describe some of the issues which the research team (Neil Birtley, Kay Dekker, Di Pryce-Evans and myself) have had to address in producing an outline specification for a dedicated system. In particular we have had to confront the peculiar, private and intuitive nature of much of the stylists' activity, which make specifying a general system particularly difficult. However, we believe that using the framework provided by management's project control structure such an outline specification is possible.

C

Keywords: car styling, graphic language, intuitive design, design processes

I Industrialdesign In the design of manufactured products the specialist activities of industrial design and a wide range of engineering design techniques are

0142-694X/92/01023-19 © 1992 Butterworth-Heinemann Ltd

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brought together. For all products where there is a conventional consumer then the industrial design specialist areas such as appearance design and the general consideration of the user interface are of immense importance. In today's marketplace the achievement of quality and reliability is a 'given' as an assumed prerequisite. Any product which is deficient in these respects is not a serious contender. However, if the product is to succeed against its competitors it must have much more. It must have designed in 'desirability' - perceived added value. This comes significantly, but not exclusively, from the industrial design contribution to the creation of the product. The engineering design inputs are concerned, amongst other things, with ensuring that the product has quality and reliability, is well made and will not break down. This gets it to the starting line, at the right price. But only one product can be the cheapest, the rest have to sell on the quality of their design. It is evident that the success of the design depends on the proper integration of the engineering and industrial design activities. How this happens varies from industry to industry, but is most particularly focused in the automobile industry.

2

Automotive design

The design of motor cars is almost always evolutionary; designs do not change radically from one model to the next. The basics stay the same, and such fundamentals as the number of wheels, the seating positions and so forth do not change. This has allowed the industry to structure its design to manufacturing processes in a very compartmentalized and sequential way, with a number of specialist inputs being involved. This has meant that more particularly than in any other product area the industrial design activities have become highly specialized and focused. The industrial designers overlap their engineering colleagues less than elsewhere, and specialize in determining the appearance and identity of the product. Until quite recently they were generally referred to as stylists. • Because they are more narrowly specialized automotive stylists exhibit the characteristics which distinguish them from engineering designers more clearly than other industrial designers. These are of particular interest in the creation of a general or integrated approach to product design for this reason • The first purpose-built styling department was created by Harley Earl at General Motors in 1927. He developed the method for creating designs on paper as various kinds of sketch, converting them to full-size orthogonal illustrations, using them to create templates etc., for the development of full size, three-dimensional models. These are usually in clay, though wood and plaster are sometimes used, especially in Italy. • The full-size model is used as the basis for all body surface information required by the engineering departments for structural design and analysis, and for tooling design and specification. It

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Design Studies Vol 13 No 1 January 1992

represents the main formal communication device between th~ stylists and the engineers.

3

1 Cornock S, 'Forms el knowing in the study of fine art', Paper

presented at the 2nd International Imagery Conference, Swan-

sea, 1985 2 Tovey M, 'Thinking styles and

modelling systems', Design Studies, Vol 7, 1986, pp 20-30 3 Rowland K, Visual education

and beyond, Looking and seeing, London (1976)

Automotive design

Industrial design processes

The sequence of activities in which the automotive stylists are given control of the early stages of the design programme and then hand over to engineers serves to further emphasise the difference between their methods of designing. The stylists are responsible for the initial conceptual thinking in the creation of the new product, and they.take that to a fairly detailed stage with fully defined surfaces, before engineering assumes control. By contrast and partly as a consequence, the purpose of much of the engineering design is to make the stylist's proposals work. This involves a lot of analytical thinking, and often considerable ingenuity. It is not, however, in any large measure creative. For virtually all motorcar manufacturers the engineering design processes are now largely computerized with CAD/CIM and much finite element work • By contrast there is little use of computing in the styling processes. To a significant extent styling is an intuitive process, with a strongly nonverbal culture, and it thus seems to be difficult to analyse and externalize its detailed processes. Furthermore the processes may vary considerably from one designer to another. It is thus problematic to devise C A D systems which are readily usable by stylists. • Automotive stylists are expected to display visual flair within a controlled and yet changing formal vocabulary. The group culture is such that they recognize their shared but exclusive language, but are unable to explain it to others. Their ability is in the form of tacit knowing, an apparently subliminal appreciation of the shapes acceptable for car design and trends in automotive styling. • Cornock I has described the thinking processes of painters and sculptors as involving an internal dialogue between an articulate critical appraiser and the proposer, which operates in the realm of nonverbal ineffable knowledge. I have suggested that for visual designers a similar internal dialogue may take place. I have identified a number of alternative thinking styles which may be employed, and they have in common the use of holistic thinking 2. The development of an overall solution proposal conceived as a whole seems to be fundamental to the process. The critical dialogue may be employed in moving it from a diffuse and undetailed concept to a sharply detailed complete proposal. This proces may employ unfocused perception 3 as an aid to initial creativity. Or the suspension of the critical appraisal may be employed to liberate the designer into contemplating alternative visual stimuli or metaphoric excursions. Wild and improbable influences may catalyse the designer's imagination. The same designer may then emp!oy carefully controlled serial techniques to refine and develop the design • A number of such thinking styles have

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been observed. It is quite possible there are more, and it is difficult to accept any one of them as the definitive standard approach. They may all be described as intuitive and most designers are quite unable to give them external expression.

4

The stylist's form language

Although the design thinking process may be private and difficult to put into words there are aspects of the activity for which a vocabulary has been developed. Groups of stylists of necessity exchange views on the body form of the vehicle design as part of the design process. This requires them to label different shapes and features being used. • Because such groups are small, and they may work together for a n u m b e r of years, their group language may be idiosyncratic and atypical. Indeed it may be used to exclude others and maintain the mystique of the styling group. For this reason it is not possible to produce a list of terms which are generally accepted, but only to produce typical examples. • My colleague Neil Birtley has documented the whole styling process for use by the research group at Coventry 4. He has characterized stylists' form vocabulary, stressing that they are liable to improvize (indeed such invention is part of what keeps them motivated), describing it thus Form and featurelines must be put into automobile body panels to give them stiffness and strength, and to stop them from wobbling under vibration ('oil canning'). The stylist's job is to use this requirement to advantage and produce aesthetically pleasing forms and shapes that still perform their structural function. Virtually no surface on an automobile is fiat, almost every panel or surface is curved in more than one direction and frequently creased and folded at the same time, possibly with other identations and piercings in the basic surface. The automobile form is built up of several such surfaces which meet at intersections, are filleted, or blend smoothly into each other. The forms may be hard and rigid, or soft and flowing or a judicious combination of both. They consist of compound curved planar surfaces, meeting, blending and intersecting with curved cones, conic sections, spheroidal segments and generating all manner of complex connecting shapes. 4 BlrUey N, 'The conventional automobile

styling process',

Bill Porter (Head of General Motors' Buick Studio) quoted by Armi 5 in The Art of

Coventry Polytechnic, 1990

American Car Design, says that car surfaces a r e . . . 'Ellipsoids, cones, warps,

5 Edson Arrnl C, 'The art of

parabolas and cantilevered shapes'.

American car design', The Pennsylvania State University Press (1980)

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Words such as 'slippery', 'exciting', 'fluid', 'soap bar', 'bath tub', 'tailored', 'sheer', 'razor look', 'taut', 'splined line', 'blitz line' (zig zag). 'whiplash line', 'Tiffany',

Design Studies Vol 13 No 1 January 1992

'sweep spear', 'windsplits' etc., all enter the language of the car stud~, especially in the USA, to describe particular forms or-connote a 'feeling'. Some forms could be described as 'bowed planar surfaces folded along carefully controlled creaselines'. Surfaces which are heavily curved in both planes would be described as 'loaded' or 'meaty', very flat surfaces or those with crisp edges or features might be described as 'taut', as having some 'tension'; flowing lines as being 'fluid'. Features are frequently applied to surfaces by cutting in a constant 'dragged' or extended form, only fading it out at the extremity o.f the paael, or stopping it and closing it off on itself. Some lines have been described as having tension like bending a piano wire, or like a bow, or a wire framework covered by a taut fabric. The VW Golf has been described as a 'sphere trying to get out of a cube' - an inflated look. Birtley stresses that lines on the body surfaces must always have a 'visual purpose', to stiffen or lighten an otherwise heavy area, or to link one visual c o m p o n e n t to another. A crowned surface may carry a 'feature', or ' b r e a k ' line, to determine the linear position. Surfaces may then build tangentially on either side to intersect on the chosen line, and where surfaces intersect softly a constant radius may follow the locus of intersection. • He also emphasises the wide range of form creation techniques which may be used. Every styling technique imaginable may be employed, moulding, squeezing, stretching, cutting, extruding, sculpting, paring and even sand papering, anything which will achieve the desired effect.

5

The graphic language of the stylist

All drawing systems use representational codes. The sketches used by automotive stylists are informal and loose, and they use a vocabulary which has many characteristics in c o m m o n with the form language. It is intended to be interpreted by a small group and it often uses a suggestive shorthand. • Thus a few lines may suggest the overall profile, with blacked-in areas to provide a reverse silhouette. A stretched ellipse may denote a highlight and hence a crowned surface or flare. A minimal half shading to a glass area may suggest a reflected horizon and indicate that the glass area is curved. A variety of touches and hints convey profile, body section, front and rear plan, suggest wheel arch cut outs, glass areas and pillar forms. The figures show typical sketches with explanatory annotations. They employ a n u m b e r of conventions in which lines represent outlines, corners, edges and high points of radii, and areas may be missed out and completed only in the viewer's mind. They also employ a n u m b e r of exaggerations including perspective, contrast, colour and

Automotive design

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texture. • The sketch design stage of the process is of relatively short duration. The sketches are intended to facilitate the rapid production of a multitude of ideas, and their communication to others in the design team.

6

Management intervention points

It is evident that the way in which stylists work, and their graphic and 3D modelling techniques do not of themselves give an objective picture of the design process. Such intuitive, nonverbal processes with the use of exclusive languages mitigates against any such description. • The problem for the Coventry research team is that if what they do cannot be defined satisfactorily then producing a CAD system or systems which will assist this process is very difficult. • One approach to the problem is to look at the overall process and to see what is already defined. The styling activity takes place within a programme which is managed, with deadlines and specified deliverables. However they work individually the stylists must produce design proposals in a proscribed format with sufficient detail for management to make decisions about the design. I have called these stages the 'management intervention points'. Management intervention points Week Issue of brief and product specification Issue of package

Automotive design

0

2

Review of competition and influences Informal discussion of concept sketches

3

Informal selection of concept sketches

4

Management review of concept proposals

5

Tape drawing presentation (some companies) Scale model presentation (some companies)

6

Presentation of reworked tape drawings or scale models

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Presentation of full-size clay model

18

8

Re-presentation as required

22

9

Approval of 3D model

26

6 (7) 9 (10)

33

At each of these management intervention points the designer or designers are expected to present to their line managers design proposals in specified forms. This may be to the section leader, studio manager, programme manager, head of department, design director or whoever. It is liable to include nondesigners at various stages, including engineers, product planners and top management. On these occasions it is of course necessary for the presentation to be in a language they will understand, and so the private form and graphic vocabularies of the stylists would be inappropriate. • The illustrative sketches of the management intervention points by Neil Birtley are based on typical procedures at Ford (Figures 6-13). Other companies will employ similar techniques although some place less emphasis on full size tape drawings, and more on scale models. • For each of these intervention points it is possible to define the people who will be involved, the location and environment, to say what will be shown, what representations and their scale, and what are the management intentions, and hence what sort of questions are asked. Out of this it should be possible to say what characteristics any alternative system must have in order for it to operate so that management can control the process, and so that it delivers what management wants. In other words we should be able to define the system which management would want its designers to use. (This may or may not be what the designers think they want!).

7

Brief, product spec. and package

This is the starting point for the designers and it is not in the same sense as the others, a management intervention point, as it does not entail the designers producing anything for evaluation. The stylists/designers receive the brief which is a document from the planning group which gives the vehicle specification (size, model range, engine sizes, features, target cost, launch date). The package is produced by engineering with planning and design and it is the form of a full-size three-view layout giving the mechanical, ergonomic and legal parameters of the proposed vehicle.

8 Review of competition and influences Informal discussion of concept sketches This will take place in the design studio around the designers' workstation, and probably involve the designers, section leader and studio manager. • What is shown will be two kinds of information, firstly for the competition and influences there will be an area of (say) 2 x A0 noticeboards covered with A4/A3 (or larger) photographs, and brochure illustration of competitive vehicles, and of lifestyle artifacts, advertising information, avant garde design trends and so forth. • Secondly the

34

Design Studies Vol 13 No 1 January 1992

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designer will show in detail sketches of design concepts, loose impressionistic representations of overall design proposals. This will probably entail 20 or so A3 drawings being discussed at the drawing board. • The management intervention in this is to ensure that the design process has begun, and is going in an appropriate direction.

9

Informal selection of concept sketches

This will take place at one end of the design studio, and it will involve a number of designers, the section leader and studio manager. • What is shown will be 10-50 A3 or A2 drawings displayed on one or more display panels (approx. 1.3m x 3m). The management intervention will be to ensure that a design scheme, something which will give the produce an appropriate identity is beginning to emerge.

10

Management review of concept proposals

This will involve the design manager, design engineering manger, and the

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Automotive design

35

cua~r UOaEL

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senior product planner. It may or may not involve the designers. They will use a viewing room in which there will be several of the display panels, covered with illustrations. • What is shown will consist of a tidy and well organized display of A3 pictures of the competition and their specifications, an A2 or larger display of the existing models and its spec., and an array of 20--40 selected design concept proposals, A3/A2 and some A1. These will be both loose theme sketches and package related, dimensionally constructed drawings. • This is a more significant point in the process than the two previous intervention points. Management is here selecting the broad design theme, the visual identity and overall character of the proposed new vehicle from the concept designs displayed. This selection will determine the approach taken for the rest of the project by the design team.

11 Tape drawingpresentation This will involve the design director, design manager, section leader, design engineering manager, the senior product planner and others, possibly the designers. They will use the large viewing room. • What is shown will consist of a selection of the relevant material from the previous intervention, 3 full-size tape drawings showing the alternative vehicle design proposals in side elevation, and a full-size drawing of the side elevation of the package with 1/2 elevations of the front and rear. • Management's intention is to select one from the three alternatives and to assess whether or not it incorporates the theme, character and identity which it was expected to have. It will be expected that design ideas from more than one will be incorporated. • They will also wish to confirm that the package requirements have been accommodated in the proposed design.

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Design Studies Vol 13 No 1 January 1992

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Scale model presentation

This is an alternative to the tape drawing presentation which is essentially the same except that instead of the three full-scale tapes, three models of 1/4 scale or similar will be displayed. Management will otherwise be making the same judgments.

13

Presentation of the re-worked tape drawings

This will involve the same group as the tape drawing presentation and an additional number of senior managers, and it will be a similar presentation except that instead of three side elevations of alternative designs, only one design will be shown as a full-size elevation, plus front and rear. This will be rendered to look like the actual vehicle. • Management at this point is making the key decision to go ahead and make a full-size clay model. If they are not happy with the design a further iteration of the tape presentation may take place. If they are largely happy but want small modifications, then it will be approved subject to their inclusion. • There

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Automotive design

37

Figure 11

is once more a V4 scale model equivalent of this stage of the process, used in some companies.

14

Presentation of the full-size clay model

This will involve all senior management in the larger viewing room. What is shown will be at least two actual vehicles, the current model and a major competitor, shown alongside a fully di-noced full-size clay model. There will be a selection of the drawings presented at earlier stages, the full-size rendered tape drawings, and the package drawing. • Management is making the major judgments to approve or otherwise the design proposal. If they are not happy with the design then they will insist on modifications and a re-presentation. If they are happy with it then the design will be approved for detailed engineering and productionizing. At this point they are asessing whether or not it will succeed in the market place. It must not only have the potential to become a manufacturable product meeting all the functional requirements of the specification, fulfilling the package

Figure 12

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Design Studies Vo113 No 1 January 1992

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Figure 13

requirements, but it must have desirability, that particular form of added value brought to the product by the flair of the industrial designers. Assessing whether or not the design has these qualities is a matter of informed judgement. However, in order to do this, management needs to see a presentation which is as close as possible to showing what the finished product would look like in the show room, or on the road.

1 5 Representation as required, and approval of 3D model The presentation of the full-size clay model may produce recommendations for changes in which case the process will be repeated, with a re-presentation of the design incorporating the modifications. • Once this has happened there will be a confirmatory presentation of the design for final approval. Further work on presenting the design will include the development of a full-size glass reinforced polyester vehicle with interior, to be used largely as a communication device to explain the proposal within the company.

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Variations on the process: multiple studio inputs

What has been described is the process as it occurs wholly within a company, using one design studio. Quite frequently companies employ more than one studio, and have them working in competition. They may also use an external consultancy to provide competitive proposals. When this happens the early stages of the process will be private to the sponsoring studio, but the management review of concept proposals, presentation of tape drawing as scale model, presentation of reworked tape drawings or scale models, presentation of full-size clay model and subsequent re-presentations, are all liable to be concerned with proposals from two or more studios. In these cases management intentions will be

Automotive design

39

the same, except that they will either be selecting between alternative proposals, or permitting the parallel development of two or more designs. Ultimately only one will be chosen. The process is otherwise similar.

17

Presentation requirements for the general process

It is evident that for management to control the stylists' design process it needs to be able to see the design proposals in ways which both permit evaluation and allow the process to continue productively. From current practice we can identify what seems to be needed. The process would seem to split into two broad categories of presentation: concept design, and design development. • Preceding each of these is the issue of the brief, specification and package

1)

Concept design requires a) Influences: simultaneous presentation of 2 x A0 area of influence illustrations b) Concept sketches: simultaneous presentation of up to 50 A3 or A2 sketches of two types (i) Theme sketches (ii) Dimensionally constrained sketches

2)

Design development requires a) Tape drawings: simultaneous presentation of three full-size elevational views, available as either line drawings or rendered Or alternatively b) Scale models: simultaneous presentation of three models of t/4 or similar scale c) Full-size clay: one (or more?) full-size di-noced representation of the design

The key characteristic of the concept design presentation would seem to be the simultaneous presentation of a large number of illustrations or sketches. The sketches are liable to be either dimensionally rigorous or loose and informal in the stylists' graphic language. • The key characteristic of the design development would seem to be the attempt to present the design as a full size realistic representation of the product. Both the full-size rendered tape drawing and the scale model are approximations, to having the actual design real size in front of you. The full-size clay is trying to do the same thing. 6 Alsh R, 'CAD software design to augment the creation of form',

YRM Architects and Planners (1990)

40

1 8 Specifying a CAD system Aish 6 has shown that in architectural practice most C A D users have abandoned the idea of one system which can do everything for them in

Design Studies Vol 13 No 1 January 1992

designing a building, in favour of using a variety of systems each with its own specialist application. Currently automotive design studios seem to be moving in a similar direction, with some use of paint box, draughting and solid modelling systems, but no integrated approach. • Concept design takes a relatively small proportion of the time taken in the design process overall. It should reduce lead times relatively little to computerize it. There may be other reasons for doing this, for instance to facilitate a total design approach in which concept engineering design took place alongside concept styling design. However, for current m~inagement control the presentation requirements are tough, requiring a multiplicity of simultaneous presentations. • Design development takes a longer period, and interfaces with the already computerized engineering procedures. It should be more amenable to a CAD approach. If a system is to be regarded as satisfactory it would seem to be necessary for it to allow designers and managers to see the design proposal full-size looking as much like the finished product as possible. There are paint box systems which will project full-size images onto a screen already in use, but they do not seem to offer great advantages over conventional techniques. • It may be possible to speed up the process of producing the scale model or full-size representation. Currently such models are produced by conventional methods, and then used as the basis for digitizing surface information onto the CAD system. If the designer had already specified the form then the model could be machined by a CNC process as an output from the C A D system. This would require the much earlier use of C A D by the stylist. Because their design processes are individual, various intuitive and private, specifying a system for them is problematic. However, it has been shown that to be usable by them in form creation it must have the following characteristics 6. a) b) c) d) e) f) g)

7 Tovey M, 'Drawing and CAD in industrial design', Design Studies, 1989, Vo110, pp 24-39

Automotive design

Inputting geometric information must be quick Geometry must be easy to specify Representations must not be overly precise Geometry must be easy to modify Reviewing alternatives must be readily possible Visual display quality must be adequate for evaluation The overall interface must be user-friendly

A system with these characteristics would probably not inhibit intuitive design processes. As products such as automobiles are evolutionary it may be possible to build from pre-existing CAD models of vehicle forms rather than starting from scratch each time. This might entail a standard list of parts as building blocks for the form design. Such an approach would more easily meet the requirements listed above.

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