Integrated manufacture: A role for virtual reality?

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E L S E V I E R International Journal of Industrial Ergonomics 16 (1995) 411-425

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Industrial Ergonomics

Integrated manufacture: A role for virtual reality?

Sue V.G. C o b b *, M i r a b e l l e D. D ' C r u z , J o h n R. Wi l son

~rtual Reality Applications Research Team (VIRART), Department of Mant{facturing Engineering and Operations Management, University of Nottingham, Nottingham NG7 2RD, UK

Abstract

Virtual Reality iVR) is fast becoming an affordable technology with potentially wide-ranging applications in many professions including education, medicine and industry. Its advantages over existing technology are primarily that users can visualise, feel involvement and interact with virtual representations of real world activities in real time.

A recently completed study, funded by the EPSRC, examined the feasibility of VR as a tool for UK manufacturing industry. Of primary interest was whether manufacturers perceive a use for VR in their industry and, if so, what impact they envisage it will have within their company. A national survey was distributed to over 2,000 UK manufacturing companies randomly selected and interviews carried out with existing users of VR technology. A brief summary of these results is presented.

A demonstration application was developed in desktop VR representing the manufacture of a consumer product in which various stages of the manufacturing process were featured including initial design, manufacture, and testing. The demonstration application is described in detail and user assessments are presented. On the basis of these findings, the potential future role of VR in integrated manufacture is discussed.

Relevance to industry

In only a short time, virtual environments have become a focus of serious consideration as a tool for manufacturing and other industry. In order that VR has greatest industrial utility we need to examine and develop its potential as a specialism-free integrating medium within a simultaneous engineering approach.

Keywords: Virtual environments; Virtual reality; Simultaneous engineering; Integrated product development

I. Introduction

The last 3 years have seen rising interest in virtual reality (VR) technology. Of the numerous published articles, both in academic press and general media, VR is described in terms of tech-

* Corresponding author.

nical descriptions of system hardware and software (tor example see Ellis, 1994; Kalawsky, 1993), futuristic scenarios of how it will influence our everyday activities (Delaney, 1994; Walser, 1990) and discussion of the potential impact this may have on society (Beardon, 1992; Schroeder, 1993; Whitby, 1993).

Part of the reason for the variety in definitions

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is that VR technology is still in a transient state of development. Having been hailed as a "revolu- tionary technology" but also a "solution looking for a problem" (Delaney, 1994, p. 15), the technology is now beginning to evolve in accordance with different application requirements. As with any evolutionary process the final product may not resemble its current state and some elements may converge with other technologies or be developed in isolation for specific application areas. As the technology develops or evolves, so too its definitions are evolving in an attempt to pinpoint more precisely what it has to offer and its influence on its participants.

It is useful at this point to make a distinction between the terms virtual reality and virtual environment: virtual reality (VR) may be taken to denote the technology and its system elements; virtual environment (VE) denotes the 'worlds' or models built in VR and experienced by the user (or more precisely, the participant). In another view, VEs might be built within a variety of technologies, from sketches to CD to simulators; it is those built in VR systems we are concerned with here.

VR comprises different system elements which divide into: - the architecture and software to produce visual

and other images and to interface with input devices,

- interface systems including sensors, effectors and input devices,

- communications systems for networking and other purposes. In terms of virtual environments, one of the

most useful first descriptions was proposed by Zeltzer (1990, 1992), describing a VE as consist- ing of three key components: - autonomy (degree to which virtual objects can

react to events), - interaction (degree of real time manipulation

of object variables), - presence (degree of fidelity of sensory input

and output channels). Zeltzer's model provides a basis for deciding

what does and, perhaps more easily, what does not, constitute a VE. Further definitions, such as those by Ellis (1994), Latta and Oberg (1994) and

Roberts and Warwick (1993), can be added to this model to produce a list of attributes which a VE must contain irrespective of what form of VR is used to create it. These attributes are: - the VE is generated by computer - the VE, or the participant's experience of it, is

three-dimensional - participants have a sense of presence in the

VE - participants can navigate around the VE - behaviour of objects in the VE can replicate

their behaviour in real life - participants can interact with the VE in real

time. More recent definitions are beginning to focus

on the 'experience' of VEs in relation to the objectives of its application. Thus, for manufacturing applications it is unlikely that the application objective will include trying to fool the user that the VE replicates the real world. What is important is to create experiences that appear and behave credibly, consistently and coherently, and that allow participants to relate the experience to the real world. The essence of the VE then is that it should enable participants to feel displaced to a new location and interact with that environment and the objects within it, and they should feel that the objects they are manipulating or observing are behaving appropriately. Partici- pants should be able to perceive some equiva- lence between the virtual and real environments, in terms of interactions with objects and of objects' interactions with each other. It is the quality of the virtual experience and its saliency (its meaning and value) for the participant that are important; the VE builder must carefully provide sensory cues to match the perceptual and motor performance the participant requires for task completion. What is not yet clear, but is of in- creasing interest, is the question of what parameters determine the quality of a virtual experience and its saliency for participants.

This paper examines the questions of VR value and requirements in manufacturing applications, with specific reference to integrated manufacture. The aim is to highlight the features of VR technology which may facilitate product development within the context of this philosophy.

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2. Virtual environments in manufacturing applications

Applications of virtual environments developed specifically for, or by, manufacturing industries are not widely reported in the academic literature. In part this may be due to the general infancy of commercially available VR technology as a whole and therefore we are at the ex- ploratory stage of application developments, some of which will remain confidential until success- fully completed. Early reports of applications for industry include the Virtual Reality and Simula- tion Initiative (Stone, 1994); network visualisation and information management at BT (Rea, 1993; Lowe, 1994) and GEC-Marconi (Stanger, 1992, 1993); and testing of a pilot virtual factory at BICC (Benford, 1994).

Related application areas such as robotics and telepresence have been explored extensively and have driven much of the development of applications in the VR field to date (see Bolas and Fisher, 1990; Degenhart et al., 1993; Ellis, 1994; Stone, 1991; Takahashi and Sakai, 1991). Reports on the use of VR for design are beginning to emerge (Breen, 1992; Spence et al., 1992; Speser and Barret, 1991; Tovey and Dekker, 1992) and, more recently, early developments of virtual assembly operations (Fernando et al., 1994; Taylor and Swift, 1994).

The use of VR in training is perhaps one of the most obvious application areas as the ability to interactively explore a virtual concept, without the restrictions or consequences presented by learning in the real world provides an ideal training environment (Bricken, 1991a,b; Kalawsky, 1993) and some development work has been applied to maintenance training (Breen, 1992; Wil- son et al., 1995).

The concept of virtual environments in integrated manufacture is not entirely new. Stone (1991) describes the advantages of computer- aided design in which both designer and end-user can observe, explore and manipulate computer- generated objects. Krishnaswamy and Elshen- nawy (1992) advocate the use of virtual reality to enrich the communication capabilities of concur-

rent engineering deployment and Haney and Romero (1994) envisage virtual environments which enable designers and developers to actually 'see' the piece or system being designed and the manner in which it functions in operational environments. On similar lines Kalawsky (1993) pro- poses virtual environments to prototype product designs in order to remove design and development risks early in the manufacturing life cycle. Such would be the advantage that "Manufactur- ing processes based on a virtual environment could revolutionise the way we design and manufacture things in the future" (p. 144). In support of this view is the virtual agile manufacturing vision described by Ross (1994) in which a customer seeking a new automobile specifies his/her own design modifications to a basic model represented in a virtual environment and takes delivery of the vehicle, exactly as specified, one week later.

3. Assessing the needs of manufacturing industry

A recent study conducted by the authors and colleagues examined the feasibility of virtual reality as a tool for UK manufacturing industry. The objectives were to identify: current perceptions of VR technology and its relevance to manufacturing industry; potential application areas of interest; and potential up-take of the technology within manufacturing (Wilson et al., 1995b).

A number of study methods were employed including a national survey distributed to over 2,000 manufacturing companies, follow-up sur- veys and in-depth interviews, site visits and hands-on tutorials. The national survey yielded 170 responses from a broad range of manufacturing companies. The results showed that, whilst there is considerable awareness of VR technology, most of this awareness is generated by media coverage and not many industrialists have yet considered its implications for manufacturing applications. Only 12 companies were identified as currently using VR and most of these have had their systems for less than 2 years. In conse-

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quence few had developed real working applications, but were exploring the potential of the technology via ' internal marketing' demonstra- tions. Applications under consideration included product design, plant layout, training, communication of ideas and concepts, product visualisation and sales and marketing.

During the course of the industrial feasibility study, it became evident that industry representatives, even those who were interested in exploring VR technology, had difficulty expressing and de- veloping ideas for specific applications of a technology they had little experience of. In order to address this problem, and to provoke more informed judgments of VR potential, a number of one-day industrial workshops were held aimed at providing hands-on experience of different types of VR systems. Central to these events was a tutorial based on a demonstration factory virtual environment built using a desktop VR system - Superscape VRT3.5, which incorporates a VR toolkit for building solid models and specifying their position and behaviour in the virtual environment. Spatial navigation is controlled using a 6-axis spaceball and interaction with virtual objects is achieved using a mouse and cursor. Out- put to the participant is via a standard PC moni- tor and stereo speakers.

Demonstration and evaluation of the virtual factory are explained below; full descriptions may be found in Wilson et al. (1995b).

4 . D e m o n s t r a t i o n a p p l i c a t i o n - V i r t u a l f a c t o r y

The demonstration factory VE embraces a design-manufacture-test facility to allow demonstration and examination of a number of attributes of virtual environments applicable to manufacturing, including: - modelling in 'virtual clay' - dimensioning, re-

forming and orienting, colouring. - rapid prototyping through interactive design

and test facilities. - walkthroughs around a factory floor. - rapid switching of viewpoints, at exocentric,

egocentric and object-centred locations - t r a i n i n g , for operation or maintenance of

equipment.

- visualisation of several stages in a manufacturing process.

- ergonomics assessment of 'fit' between different user sizes and product dimensions. In order to give coherence to the demonstra-

tion, an example scenario was created representing a virtual factory producing toy vehicles for 2-6-year-old children. The plastic body and roof components of the product are manufactured at this factory using the process of injection moulding. The participants had the facility to modify the product design in dimensional and aesthetic qualities, and could test the product's suitability for different users (e.g. children of different ages and sizes). It was also possible to view the injection moulding process in operation and follow the components along the production line.

The hands-on demonstration was divided into two main parts:

(1) Construction of a virtual environment This part provided experience of creating vir-

tual objects and placing them in the virtual environment with associated real world properties in order to illustrate how models are created. This also served to provide contrast between VEs and other technologies.

(2) Use of a virtual environment This part encouraged the participants to ex-

plore different attributes of the virtual environment within three broad categories: factory walkthrough, visualisation of a manufacturing process and design modification. Division into three dis- tinct categories such as these highlighted the features of the VE relevant to each application domain and provided a focus for appraisal of these features. In practice the participants had complete freedom to explore the VE and all its features in any order they chose.

4.1. Factory walkthrough

This feature demonstrated how the participant can navigate through the VE and examine it from different viewpoints. Eleven viewpoints were set up at different locations around the factory, some of which enabled movement control of virtual objects. The spaceball was used to control move-

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Fig. 1. Egocentric view as the participant walks around the factory floor.

Fig. 2. Object-centred view from inside the forklift truck. Movement of the spaceball replicates driving and the levers can be used to lift pallets.

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ment of the participant and also virtual objects around the factory environment. Appropriate di- rectional control inputs were responsive according to the type of object being manipulated. Three different types of object manipulation were represented in the tutorial: (1) Human walking (egocentric view) in which

the eye height was set at approximately 1.6m and movement control restricted to 2 degrees of freedom (DOF) - forwards/back and left/right obeying natural physical laws - for example, doors must be opened before pass- ing through, the participant's 'body' is fixed to the floor and can only be raised by 'climb- ing' (Fig. 1).

(2) Driving a vehicle (object-centred view) in which the viewpoint represented that of an operator seated inside the vehicle and movement control assumed the characteristics appropriate to that type of vehicle (Fig. 2).

(3) 'Ghost mode' (exocentric view) in which the participant had complete freedom of movement around the virtual environment in all 6 DOF, defying all natural boundaries (e.g. movement through hard surfaces such as walls) (Fig. 3).

4.2. Visualisation of the manufacturing process

This feature demonstrated the effect of simu- lating operations and visualising interactions between different objects and related functions. It was possible to: - switch on both moulding machines to start

operation; - observe the process in operation from unusual

viewpoints (e.g. watching the hopper filling with plastic beads as viewed from above the machine) (Fig. 4);

Fig. 3. Exocentric view. Here the view is placed in the ceiling above the factory floor allowing the participant to see both the production line and the design room.


Fig. 4. Looking from above the hopper the participant can observe the material flow.

Fig. 5. By making the side panel invisible the participant can observe the injection moulding process.

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Fig. 6. The gyrotool enables modification of the product design by selecting the required function and direction of change

Fig. 7. The window inset shows changes to the product manufacture as a result of design modification.


- remove side panels of the machine to observe what is going on inside (Fig. 5);

- 'fly into' the machine to observe operations from within;

- observe finished parts moving down the con- veyor lines, identifying any bottlenecks.

4.3. Design modification

This feature demonstrated the use of a 3D sculpting tool for modification of the product design prototype. This gyrotool was developed on the basis of previous research which examined orientation issues in the remote control of industrial robots (Gray et al., 1992; Gray Cobb, 1991). The gyrotool is operated using the spaceball and effectively 'carried around' with the participant. In this way all directions (X,Y,Z) are always fixed relative to the object but the designer is not required to interpret which direction they need to alter - simply stretching the object along the direction required will be sufficient (Fig. 6). A menu is provided to select different design modification facilities (stretch, shrink, change colour).

The effects of changes made could be viewed both in terms of the manufacturing process (Fig. 7) and a crude ergonomics test for intended end- users (Fig. 8).

5. E v a l u a t i o n o f the v i r tua l factory

The virtual factory was demonstrated on site in companies, where informal evaluations and dis- cussions were used. The main formal evaluation was carried out at our workshops with twenty- three representatives from a wide range of industries including engineering, motor manufacture, construction, retail, telecommunications, information technology and computer systems manufacture. Attendees were divided into small groups and were encouraged to work as a team and to discuss the activities they were performing. They took control of operating the VR system and making decisions on how to interact with the virtual environment. At the end of each tutorial stage they completed response sheets indicating their impressions of the specific features demon-

Fig. 8. Placing the participant inside the product design (object-centred view) allows assessment of 'fit ' for the end user.

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strated and their utility for industrial applications.

The results are summarised according to the following categories: - usefulness of the features for industrial appli-

cations; - usability issues; - potential industry take-up of VR technology.

In design modification the respondents found all the operations, including selection of product components and design features, use of the gyrotool to change the product design, and viewing the consequences of changes in production and for the end-user, easy to perform.

5.3. Potential industry take-up of VR technology

5.1. Usefulness of the virtual factory to industry

The respondents considered the walkthrough facility to be useful to industry but were mixed in their opinions of the usefulness of the visualisation and design facilities. Reasons given for these responses were that the ability to walkthrough and interact with virtual models before applying findings to real life could be extremely useful, but that the current user interface is difficult and the system is not suitable for complex modelling. Moreover, although the design facility may be useful for design/planning activities, it was felt that the demonstration fell far short of current CAD systems in performing these functions. Sug- gested improvements to make these facilities more useful to industry were: the use of a better control interface, provision of navigation and visual cues, improved graphics quality and provision of appropriate sound effects.

5.2. Usabifity issues

Usability of VR was measured in terms of how easy or difficult the respondents found it to perform specific operations. They differed widely in their ability to recognise where they were in the virtual environment, drive the forklift truck and lift the pallet. However, determining where to go in the virtual environment and moving around using walk view presented no difficulties to the respondents.

In visualisation of the manufacturing process the respondents had no difficulty in identifying the most useful viewpoint to use but differed in their ability to select or move to the viewpoint required. Most of them found the use of 'ghost mode' to fly into the machine and recognising where they were inside the machine very difficult.

The respondents were given six criteria and asked to indicate whether these features would be good enough to encourage engineers or designers (as appropriate) to use VR At least 50% of the respondents were positive about the following aspects of each feature explored: - Walkthrough - walkview, use of viewpoints,

feeling of immersion, graphics; - Visualisation - use of viewpoints, movement

control virtual objects; - Design - use of viewpoints for user testing,

sculpting tool for resizing, facility to change product features. At least 50% of the respondents were negative

about the amount and quality of detail represented in both the visualisation and design features.

The overall finding of the feasibility study, from both survey and demonstration methods, was that in spite of current limitations of VR technology, largely due to its immaturity, it is seen as offering potential utility in manufacturing applications. All but one of the respondents sur- veyed in-depth considered VR to have a future in their company and expect to be using it within the next 5 years. More information is required about the technology in general and how it might be applied. Applications suggested as appropriate include plant layout, training, marketing and communication, and a large majority of respondents indicated that they would expect to use VR in concurrent engineering. Potential advantages of VR include cost and time benefits, sales aid, visualisation, added value to simulation and communication, although the respondents were not able to specify how these benefits would be re- alised. The perceived disadvantages of VR are the initial cost of implementation and current immaturity of the technology. Specific require-

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ments for manufacturing applications include: greater detail of display whilst maintaining re- drawing speed, easier programming and file transfer, improved texture mapping and an easier user interface. In addition, the lack of detailed case studies demonstrating benefits of VR to industry may be restricting implementation.

Perhaps the view of manufacturing industry in general can best be expressed in the words of one respondent: "At the moment I know of it but very little about it. I believe VR will become important but only as it becomes cost effective".

Although they had the opportunity to try a number of different systems during a full day, the majority of the respondents indicated that they did not consider a head mounted device or sound effects would improve the use of VR for visualisation or design but had mixed views about the walkthrough facility. Most of the respondents reported that they did feel ' immersed' or 'involved' in the desktop virtual environment and were im- pressed with its potential indicating that it would be the most suitable VR system for their industry at least in the foreseeable future.

6. Discussion

The objective of the virtual factory environment was to explore and demonstrate the potential use of VR for manufacturing applications in order to promote informed judgment and com- ment of its future role in manufacturing from industry representatives. One of the most important features of the demonstration as a whole was that any changes made by the participant within one facility (e.g. design modification) influenced the activities or results in another facility (e.g. production visualisation) and so participants were exploring all of the world interactively. In this way a simple representation of the utility of the virtual factory in integrated manufacture was explored by potential industrial users.

As the users explored the design facility it was found that because the design model is calculated in real time, it is possible to explore the virtual object in a similar way to how one would explore a real object. The designer can move freely around

the VE examining the object from different angles, s / h e can pick it up and rotate it, try it out for 'fit' with other virtual objects and can interact with it to explore and test its functional behaviour (Wilson et al., 1995a). The primary advantage of VR in design then is that it provides a good medium for visualisation of the prototype. Its specific strength is that it can give properties to virtual objects not within the scope of conven- tional design activities. The designer and others can view a simplified model of the product - simplified in that it does not carry all the exact details specified in the design model but is not necessarily graphically poorer - and can examine it visually very quickly from alternative angles and viewpoints. It is also possible to explore some of the functional features of the design such as opening doors, sitting in chairs or operating control panels.

The process planner can decide upon the operation sequence for how products are to be made and which equipment should be used. VR may provide a visualisation tool to assist the process planner in gaining a 'feel ' for the compo- nent rather than relying upon a static drawing. In process scheduling decisions are made concern- ing some optimum or preferred use of machines to manufacture the product. A VR representation of the process could be used to visualise material flow via different production routes and to identify potential bottlenecks.

In assembly planning the process engineers need to specify methods and sequencing of assembly. This may require putting together several sub-assemblies and decisions need to be made about how these sub-assemblies should fit together physically and in what order; the assembly task itself will involve parts manipulation (transfer and orientation) and insertion with other sub-assemblies. These decisions are currently aided using design for assembly (DFA) systems but these usually represent the relevant information qualitatively in terms of task difficulty. VR can provide similar information in a visual form, which offers great potential for the assessment of task difficulty in both assembly and disassembly. A visual representation of the physical position- ing of objects within a specified space will allow

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the user to explore access space available and define reach parameters, including the need for specialised tooling.

Two of the main attributes that VR technology offers to industry are rapid visualisation and real-time interactivity. This means that one of the most obvious applications of VR is within a pro- gramme of rapid prototyping (RP) leading even- tually to integrated product development. At present, discussion of this sort of application has centred on the linkage of VR and RP in product development, with the virtual environment used to facilitate and enhance visualisation and under- standing of a situation or object or data, allowing exploration from different viewpoints. However, a wider approach, embracing the philosophy of support for integrated manufacture may produce a VR application with great utility. In this view, VR becomes an integrating technology both for technical systems and, just as important, also between all the different personnel involved, including suppliers and customers.

The interactive way in which users can take control of and explore situations makes virtual environments ideal for training and maintenance purposes. This has been a focus of much in-company work with VR with perceived advantages of reducing the need for on-the-job training, thus reducing machine down-time; limiting the need for manuals, and allowing discussion around virtual models which should be much easier to un- derstand and interpret. What is required now is a formal evaluation of the effectiveness of virtual reality, assessing both how it fits within existing training programmes and evaluating outcomes against those found from other training media. The research should also seek to produce guid- ance on appropriate forms of VEs for training in terms of level of detail, degree of interactivity, use of prompts or explanatory windows and so o n .

Perhaps the greatest advantage of these attributes is in how they will facilitate the communication of ideas and concepts. Discussion around a virtual model could produce rapid design itera- tions with inputs from multi-skilled design and production teams. Extending the virtual environment to include the production process will facili-

tate exploration of the process and assessment of the demands placed upon operators. For example, VR may allow 'walk through' types of assessment, perhaps of workspace layout, and also 'capacity limits' assessments, perhaps of allow- able forces or postures in work tasks. A first suggested domain is planning and design for assembly (Fernando et al., 1994).

In order to be valuable in these ways, and because of technological limitations, the virtual model detail may have to be kept to a minimum. Thus it may not be rich enough to contain all the domain-specific information but will be a simplified representation that contains only the relevant information. It is often the case that we do not need to replicate 'reality' closely, but some- times we might wish to accurately model materi- als, for instance, individual molecular behaviour. The problem with VR is that these calculations are usually too complex to perform in real time. Therefore, by definition, VR will restrict its own use for applications. The solution may be that the system accesses a calculated data set to produce the visual model.

The question of sheer processing power, and its use, is critical of course. CAD models in, say, motor manufacture, may require files of about 80Mbytes; clearly, at the moment, files of this size would cause VR systems to 'seize up'. However, CAD files are this size because the emphasis is on detailed rendering of models whereas the emphasis of VR is on interactivity and presence. It is a classic case of apples and pears - CAD is intended for certain uses and VR for others; needs of user companies will determine which system is to be employed. Beyond the present however, these two technologies - or at least the foci of rendering and representation faithfulness, interactivity and presence - will merge and development work carried out n o w in VR will pay dividends.

However, communication links between VR and other technologies are not yet refined enough to support such information transfer (Stanger, 1993). Technology integration generally is an obvious requirement for VR to be used within integrated manufacture. Moves towards improved communication facilities are underway, as illus-

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trated by the recent link-ups between two of the UK's three main VR developers and major international computer companies. Virtuality and IBM have announced their collaboration on 'Project Elysium', an immersive/desktop reality development system which should include relatively affordable world-building facilities. Division and HP have also signed a product development agree- ment, which amongst other advances should provide improved VR graphics performance. With these developments, together with the growing research into computer networking (see for example Benford and Fahlen, 1993; Henderson, 1991; Li and Mantei, 1992), it is possible that 'virtual manufacturing' concepts such as those suggested by Onasato and Iwata (1993) and Ross (1994) will be achievable in the near future.

7. Conclusions

The facility of computer-generated solid models of virtual objects and environments that can be interactively explored in 3D, and modified and recreated in real time, offers enormous potential for integrated manufacture. The designer would be able to quickly visualise the product concept and represent alternative design solutions. Per- sonnel from other manufacturing and business functions would be able to view the product design in ways which offer less ambiguous interpre- tation. One specific benefit from using virtual environments for this kind of co-operative communication is that all participants can have some influence on design solutions in an interactive fashion and will be able to view the consequences of changes made almost immediately.

VR does have a potential role in integrated manufacture but is probably not yet ready to fulfill this role. User up-take has been slow to date, and the lack of demonstrated benefits, together with high anticipated costs, and the immaturity of the technology are causes. If VR is to be widely used in integrated manufacture, system developers must provide adequate and effective integration with existing technologies. At present this is difficult with CAD files, never mind stan-

dards such as STEP and CALS. However, com- mercial facilities and collaborations as mentioned above will mean that this may soon be rectified. Current technical limitations almost certainly will not be a problem of the future as improvements are continually being made. However, it is important that the needs of industry users with regard to this technology are taken into consideration in future system development. The researcher com- munity must work closely with manufacturing industry to define and explore the real utility of VR within integrated manufacture. More effort is required in the development of existing applications that demonstrate actual benefits to industry.

Virtual Environments have a great potential for manufacturing applications, with advantages over existing technologies in several areas, but they will not be a panacea for industry even when further developed. We need to be sure about what the attributes of VR are that give it an edge, for certain applications, over existing technologies or by integration with them. VR is a very flexible technology with vast possibilities for development. Our feeling is that slow take-up at present is due more to questions of how to inte- grate VEs within existing technologies and operations, for instance facilitating file transfer, and of how VR fits into the company infrastructure, than to intrinsic deficiencies in VEs themselves.

The costs of a company 'investing' in VR are difficult to establish. Capital costs are relatively low - less than £ 5,000 for desktop capability, and between £ 15,000-£60,000 for reasonable quality head-mounted device systems. Competent technical staff would be producing useful worlds in a matter of months. However, capital costs and world-building facilities (and thus building and training times) are improving all the time. The unknown costs are to do with integration - technical with other systems and organisational with how the., work of all company functions will be affected.

Already many potential user companies feel that VR is an important technology of the future and will be good for communicating ideas and adding value to 3D visualisation, and several are investigating the technology using different VR systems. One of the key application areas, which

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itself will guide VR system development, is integrated product development and manufacture. It is essential that the ongoing development of VR technology is directed toward providing what is actually required if it is to have any place within manufacturing industries.

Acknowledgements

Much of the work described in this paper was carried out under grant G R / J57643 funded by the Control, Design and Production Group of the EPSRC. We would like to thank all of the companies who took part in the study as well as the other members of the VIRART research group, especially Richard Eastgate and Brendan Collins for their vital input to the research study and development of the factory virtual environment. Dr. Richard Cobb and Professor Nabil Gindy are thanked for their advice on both the manufacturing process demonstrated and also the utility of VR for integrated manufacture.

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Documents

Integrated manufacture: A role for virtual reality?