Journal of Materials Processing Technology 155156 (2004) 18341838

Virtual reality applications in manufacturing process simulationT.S. Mujber, T. Szecsi, M.S.J. Hashmi

School of Mechanical and Manufacturing Engineering, Dublin City University, Glasnevin, Dublin 9, Ireland

Abstract

Virtual reality (VR) is a rapidly developing computer interface that strives to immerse the user completely within an experimentalsimulation, thereby greatly enhancing the overall impact and providing a much more intuitive link between the computer and the humanparticipants. Virtual reality has been applied successfully to hundreds if not thousands of scenarios in diverse areas including rapid proto-typing, manufacturing, scientific visualisation, engineering, and education. This paper gives an overview on the virtual reality applicationsin manufacturing processes. 2004 Elsevier B.V. All rights reserved.

Keywords: Virtual reality; Virtual manufacturing; Virtual environment

1. Introduction

The current demand to reduce the time and cost involvedin taking a product from conceptualisation to production hasforced companies to turn to new and emerging technologiesin the area of manufacturing. One such technology is virtualreality (VR). The origins of virtual reality can be traced asfar back at least as the ultimate display [1]. Virtual realityallows a user to step through the computer screen into athree-dimensional (3D) world. The user can look at, movearound, and interact with these worlds as if they were real.The primary concept behind VR is that of illusion. It fo-cuses on the manifestation of the fantasy world of the mindin computer graphics. It is also a new media for informationand knowledge acquisition, and representing concepts ofideas in ways not previously possible [2]. With the advanceof computer technology, VR systems could contribute effi-ciently in various applications. Virtual manufacturing (VM)is one of the applications of applying VR technology inmanufacturing applications. Researchers at the University ofMaryland have introduced the concept of virtual manufac-turing in 1995 [3], while the contribution and achievementsof VM have been reviewed by Shukla et al. [4] Virtual man-ufacturing is defined as a computer system which is capableof generating information about the structure, status, andbehaviour of a manufacturing system as can be observed ina real manufacturing environment [5]. The vision of virtualmanufacturing is to provide a capability to manufacture inthe computer. That means VM will provide a modelling

Corresponding author. Tel.: +353 85 1420534.E-mail address: tariq.mujber2@mail.dcu.ie (T.S. Mujber).

and simulation environment so powerful that the fabrica-tion/assembly of any product, including the associated man-ufacturing processes, can be simulated in the computer [6].

1.1. Types of VR systemsIvan Sutherland has introduced in a seminal paper the

key concepts of immersion in a simulated world, and ofcomplete sensory input and output, which are the basis ofcurrent virtual reality research. His challenge was to setthe screen is a window through which one sees a virtualworld to make it looks real, acts real, sounds real, andfeels real [1]. Although it is difficult to categorize all VRsystems, most configurations fall into three main categoriesand each category can be ranked by the sense of immer-sion, or degree of presence it provides. These categoriesinclude non-immersive (Desktop) systems, semi-immersiveprojection systems and fully immersive systems as shownin Table 1. Vast amount of VR software packages availableon the market, which can be used to develop virtual envi-ronments for different applications (e.g. Superscape VRTand SENSE8). Moreover, software packages have beendeveloped for virtual applications in manufacturing (e.g.DELMIA). DELMIA package [7] provides authoring appli-cations that can be used to develop and create virtual man-ufacturing environment to address process planning, costestimation, factory layout, ergonomics, robotics, machining,inspection, factory simulation, and production management.

1.2. Virtual reality applications in manufacturingManufacturing industries are the most important contrib-

utors to prosperity in the industrialised countries. However,

0924-0136/$ see front matter 2004 Elsevier B.V. All rights reserved.doi:10.1016/j.jmatprotec.2004.04.401

T.S. Mujber et al. / Journal of Materials Processing Technology 155156 (2004) 18341838 1835

Table 1Types of VR systems

VR system Non-immersive VR Semi-immersive VR Fully-immersive VR

Input devices Mice, keyboards, joysticks and trackballs. Joystick, space balls and data gloves. Gloves and voice commands.Output devices Standard high-resolution monitor Large screen monitor, large screen

projector system, and multipletelevision projection systems

Head mounted display (HMD), CAVE

Resolution High High LowmediumSense of immersion Non-low Mediumhigh HighInteraction Low Medium HighPrice Lowest cost VR system Expensive Very expensive

it is becoming increasingly difficult to meet customersdemands and to compete. The advances in virtual realitytechnology in the last decade have provided the impetus forapplying VR to different engineering applications such asproduct design, modelling, shop floor controls, process sim-ulation, manufacturing planning, training, testing and veri-fication. VR holds great potential in manufacturing applica-tions to solve problems before being employed in practicalmanufacturing thereby preventing costly mistakes. Virtualreality not only provides an environment for visualisationin the three-dimensional environment but also to interactwith the objects to improve decision making from bothqualitative and quantitative perspectives [8]. The followingsection discusses the use of virtual reality in manufacturingapplications, which include, design, prototyping, machin-ing, assembly, inspection, planning, training and simulation.Virtual reality applications in manufacturing have beenclassified into three groups; operations management, man-ufacturing processes, and design. A brief description ofevery group and its relevant subgroups will be providedin the coming sections.

1.2.1. DesignVirtual reality may play very significant rule in design

a new product. VR technology has been applied into twodifferent applications in design; design and prototyping asshown in Table 2. The benefits of the applying VR in designare shown in Table 4. VR provides a virtual environment forthe designers in the conceptual design stage of designing anew product; the designer could produce 3D sketch of a

Table 2Manufacturing design applications

Application Definition Example

Product design Virtual design is the use of VR technology to provide the designerwith a virtual environment to evaluate the design, evaluatealternate designs, effectively interact with the product model andconduct ergonomic studies using full human body tracking.

A virtual workshop for mechanical design was developed atMassachusetts Institute of Technology. The goal of the project wasto develop a simulated workshop for designers to do conceptualdesign work while having to take into account manufacturingprocesses. The simulated workshop consists of a band saw, a drillpress, a milling machine, a radial arm saw and a table saw. [9]

Prototyping Virtual prototyping means the process of using virtual prototypesinstead of or in combination with physical prototypes, forinnovating, testing and evaluating of specific characteristics of acandidate design.

University of Illinois, Chicago, and Purdue University havedesigned and implemented a prototype of a virtual reality basedcomputer aided design system. The focus of this work is to allowa simplified method of designing complex mechanical partsthrough the use of virtual reality techniques [10].

product in the virtual environment. At this stage, functionalexperimentation of mechanical features such as hinges, as-sembly, etc. could be performed to evaluate the conceptualdesign and modifications could be made as required. Oncethe designers are satisfied with their design, then the de-sign could be detailed to make the necessary modifications.In the product development process, prototyping is an es-sential step. Prototypes represent important features of aproduct, which are to be investigated, evaluated, and im-proved. Virtual prototyping could be used before building thephysical prototype to prove design alternatives, to do engi-neering analysis, manufacturing planning, support manage-ment decisions, and to get feedback on a new product fromprospective customers. The virtual environment for proto-typing should include [6].

(a) Functionality: the virtual prototype should be clearlydefined and realistically simulated to address productfunctionality and dynamic behaviour.

(b) Human interaction: the human functions involved mustbe realistically simulated, or the human must be includedin the simulation.

(c) Environment: an offline computer simulation of the func-tions can be carried out, or a combination of computeroffline and real time simulation can be carried out.

1.2.2. Operations managementOperations management has been classified into three

categories; planning, simulation and training. The benefitsof applying VR technology to these categories are shown

1836 T.S. Mujber et al. / Journal of Materials Processing Technology 155156 (2004) 18341838

Fig. 1. Fully immersive VR environment.

in Table 4. Due to the necessity of a smarter factory plan-ning; Virtual reality is a useful method to improve theunderstanding of the plans and to support interdisciplinarydiscussions. Fig. 1 shows fully immersive VR environment,which has been used as a tool for future factory design.This environment has been developed to provide a visual,three-dimensional space in which to explore the effect ofvarious product mixes, inspection schedules, and workerexperience on productivity [11]. Virtual reality-based train-ing is the worlds most advanced method of teachingmanufacturing skills and processes to employees. Usingcutting-edge VR technology, training takes place in a real-istic, simulated version of the actual facility, complete withthe actions, sights, and sounds of the plant floor [12]. Someof the simulation products provide some form of visualisa-tion for depicting model output (e.g. Witness 2003, Simul8,and Flexsim). Fig. 2 shows a virtual environment createdby Witness VR for a factory [13]. Table 3 shows the appli-cations of VR technology on the operations managementcategories.

Table 3VR applications in operations management

Area VR applications

Planning VR can lead to an optimal planning of a manufacturing system by giving a visual environment to the all person involved in theplanning process to monitor the factors that lead to inadequate planning results and delay the start of product.Visual comparison of possible solutions based on human experiences and facts lead to a rapid start of production and robustmanufacturing processes [14].

Simulation VR convince the people who do not believe, know in the simulation tools and understand the capabilities of simulation. [21]VR helps to verify the model logic and real-world behaviour of the model [15].VR is an important factor in the verification process as it provides a visual trace of events as they happen.VR gives an opportunity to the people who have not built the model to verify it.VR supports the simulation tools to understand the results and the dynamic behaviour of the model.VR provides virtual environment to the employees, mangers and non-technical audience to communicate and understand thestatistical outcome of a simulation.

Training VR offers the best training by allowing each employee have a full access to the entire facility.The virtual environment of the facility will allow the employees to practice existing and new tasks in safe, and see how aproduct takes shape as it moves through the manufacturing system, which result more effective training.

Fig. 2. Virtual factory created by witness VR.

1.2.3. Manufacturing processesManufacturing processes has been classified into three

different areas; machining, assembly, and inspection. Table 4gives a brief description on the benefits of using VR inmanufacturing processes.

1.2.3.1. Machining. Virtual machining mainly deals withcutting processes such as turning, milling, drilling, andgrinding, etc. The VM technology is used to study the fac-tors affecting the quality, machining time of the materialremoval process as well as the relative motion between thetool and the workpiece. Fig. 3 shows an engineer uses aVirtual reality semi-immersive environment to simulatethe use of a hexapod machine tool. [16] University of Bathin Bath has developed an interactive virtual shop floor con-taining a three axis numerical control milling machine anda five axis robot for painting. The user can mount a work-piece on the milling machine, choose a tool and performdirect machining operations, such as axial movements orpredefined sequences [17].

T.S. Mujber et al. / Journal of Materials Processing Technology 155156 (2004) 18341838 1837

Table 4Summary for virtual reality benefits in manufacturing applications

Area Benefits

DesignDesign To allow the whole design team to work together in the virtual environments.

To improve visualisation of the product by allowing the user to co-exist in the same environment with the product model.To improved interaction with design in terms of more intuitive model manipulation and functional experimentation.

Prototyping To reduce significantly the amount of hardware prototypes during conception, design, and evaluation of new products.To provide a virtual environment for innovating, testing and evaluating of specific characteristics of a candidate design.

Operations managementPlanning To improve the understanding of the plans and to support interdisciplinary discussions.

To allow the users to interact and change the model during runtime.To enable unskilled users to understand and participate in the planning process.To support the technological as well as the economical modelling of diverse production planning scenarios.

Simulation To convince the use the simulation tools.To verify and validate a simulation model.To enable the user to understand the results.To provide a virtual environment for communication of results.To achieve the credibility for the simulation. [21]

Training To duplicates an entire manufacturing process to a virtual environment to give trainers their own factory to learn in.To provide a user with an environment to explore the outcomes of their decisions without risk themselves or equipment.To allow the employees to practice existing and new tasks in safe.

Manufacturing processesMachining To evaluate the feasibility of a part design and the selection of processing equipment.

To allow the user to study the factors affecting the quality, machining time and costs based on modelling and simulationAssembly To reduce design cycle time, re-design efforts, and design prototypes. [18]

To predict the quality of an assembly, product cycle and costs.To address assembly and disassembly verification.

Inspection To model and simulate the inspection process, and the physical and mechanical properties of the inspection equipment.To provide an environment for studying the inspection methodologies, collision detection, inspection plan, factors affecting theaccuracy of the inspection process, etc [20].

1.2.3.2. Assembly. Virtual assembly is a key component ofvirtual manufacturing and is defined as: the use of computertools to make or assist with assembly-related engineeringdecisions through analysis, predictive models, visualisation,and presentation of data without realization of the productor support processes. In assembly work [18], VM is mainlyused to investigate the assembly processes, the mechanical

Fig. 3. Virtual machine tool.

and physical characteristics of the equipment and tooling,the interrelation among different parts and factors affectingthe quality based on modelling and simulation. Virtual re-ality can be used for assembly/disassembly operations. Forexample, can a human worker assemble a part or a com-ponent? And then can the part be disassembled for ser-vice and maintenance at latter stages? Other questions needto be addressed, too: is it difficult or easy to assem-ble/disassemble a part? How long does it take? How stressfulis it in terms of ergonomics? Is there enough room for tools?.

1.2.3.3. Inspection. Virtual inspection makes use of theVM technology to model and simulate the inspection pro-cess, and the physical and mechanical properties of the in-spection equipment. This aims at studying the inspectionmethodologies, collision detection [19], inspection plan, fac-tors affecting the accuracy of the inspection process, etc.[20].

2. Conclusions

VR can be a powerful tool for testing and evaluating newproducts and ideas, decreasing the time to market and reduc-ing product cost. Today, only large companies use virtualtechnologies and benefit from its competitive advantages.VRs widespread use and acceptance will require devices

1838 T.S. Mujber et al. / Journal of Materials Processing Technology 155156 (2004) 18341838

and software with higher quality and lower cost. ExistingVR technology has been applied to solve clients real-worldproblems, and has increased profitability, decreased time tomarket, and increased worker safety. Manufacturing pro-cesses and design can be defined, modelled and verified be-fore they can be actually implemented. Virtual realty offersthe engineers new ways to not only visualize their prob-lems but also to interact with the environment to solve theproblems effectively and efficiently. These visualisations,combined with interaction can improve the decision-makingcapabilities of engineers thereby improving quality and re-ducing the development time for new products. If these VRtechnologies are effectively implemented, it can result inimproved product design, with superior quality leading tobetter customer satisfaction.

Acknowledgements

The authors gratefully acknowledge the financial supportreceived through a grant from AMT Ireland.

References

[1] I.E. Sutherland, The ultimate display. Proceedings of IFIPS Congress,vol. 2, New York, NY, 1965, pp. 506508.

[2] K. Pimentek, K. Teixeira, Virtual reality: Through the New LookingGlass, first ed., Windcrest/McGraw-Hill, PA, 1993.

[3] E. Lin et al., Contribution to Virtual Manufacturing BackgroundResearch, http://www.isr.umd.edu/Labs/CIM, 1995.

[4] C. Shukla, V. Michelle, F.F. Chen, Virtual manufacturing: anoverview, Comput. Ind. Eng. 31 (1996) 7982.

[5] K. Iwata, M. Onosato, K. Teramoto, S. Osaki, Virtual manufacturingsystems as advanced information infrastructure for integrated manu-facturing resources and activities 46 (1997) 335338.

[6] Melissa Saadoun, Virtual Manufacturing and its Implications, France,1999.

[7] DELMIA, http://www.delmia.com.[8] R.S. Tiruvannamalai, Virtual Reality in Design and Manufacturing

Applications, 2002.[9] J.W. Barrus, The Virtual Workshop: A Simulated Environment for

Mechanical Design, Ph.D. Dissertation, Massachusetts Institute ofTechnology, September 1993.

[10] S.N. Trika, P. Banerjee, R.L. Kashyap, Virtual Reality Interfaces forFeature-Based Computer-Aided Design Systems, 1996.

[11] Virtual Reality applications centre, http://www.vrac.iastate.edu/research archive/manufacturing/factory/index.php.

[12] Manufacturing training, Sunrise Company, http://sunrisevr.com.[13] Anthony P. Waller, John Ladbrook, Experiencing Virtual Factories

of the Future, 2002.[14] D. Schaefer, C. Borgmann, D. Scheffter, Factory Planning and the

Potential of Virtual Reality, 2001.[15] S. Robinson, Simulation Model Verification and Validation: Increas-

ing the Users confidence, Winter Simulation Conference, 1997,p. 57.

[16] NIST, http://www.nist.gov/public affairs/gallery/vrmanu.htm.[17] G.M. Bayliss, A. Bower, R.I. Taylor, P.J. Willis, Virtual Manufac-

turing, Presented at CSG 94Set Theoretic Modelling Techniquesand Applications, Winchester, UK, 1994, pp. 1314.

[18] S. Jayaram, H. Connacher, K. Lyons, Virtual assembly using virtualreality techniques, Comp. Aided Des. 29 (1997) 557584.

[19] R. Tesic, P. Banerjee, Exact collision detection using virtual objectsin virtual reality modelling of a manufacturing process, J. Manufact.Syst. 18 (1999) 367376.

[20] W.B. Lee, C.F. Cheung, J.G. Li, Applications of virtual manufacturingin materials processing, J. Mater. Process. Technol. 113 (2001) 416423.

[21] Matthew W. Rohrer, Seeing is believing: The Importance of Visual-isation in Manufacturing Simulation, Winter Simulation Conference,2000.

Virtual reality applications in manufacturing process simulationIntroductionTypes of VR systemsVirtual reality applications in manufacturingDesignOperations managementManufacturing processesMachiningAssemblyInspection

ConclusionsAcknowledgementsReferences