VIRTUAL REALITY IN MANUFACTURING

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Nov 14, 2013 (3 years and 10 months ago)

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VIRTUAL REALITY IN M
ANUFACTURING



Karunakaran Prabhu


Masters of Science Graduate Student



Submitted in Partial Completion of the Requirements of

INDEN 5303

Advanced Manufacturing Systems Design












This paper was developed by the above named gr
aduate student in partial
fulfillment of course requirements. No warranty of any kind is expressed or
implied. Readers of this document bear sole responsibility for verification of its
contents and assume any/all liabilty for any/all damage or loss resul
ting from its
use.







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i


Table of Contents

ABSTRACT

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1

Keywords

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1

INTRODUCTION TO VIRTUAL REALITY

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...

1

Components of Virtual Reality Syste
ms

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2

VIRTUAL REALITY AND SIMULATION

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4

VIRTUAL REALITY IN MANUFACTURING

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4

Virtual Design and Prototyping

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5

Virtual Assembly Planning

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6

VIRTUAL CORPORATIONS

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7

VIRTUAL REALITY SOFTWARE SYSTEMS

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8

BENEFITS OF VIRTUAL REALITY IN CIM

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9

RESEARCH ISSUES

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11

Limitations of CAD

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11

Network Communications

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11

Limitations of Virtual Reality Technology

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11

Human and Organizational Behavior

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11

Cost Efficiency

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11

CONCLUSIONS

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12

Bibliography

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13


List of Figures

Figure 1.1:

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3

Figure 1.2:

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3


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Figure 1.5:

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1


ABSTRACT

Virtual Reality (VR) as the name suggests, is the closest man can get to reality with his
present capabilities. Virtual Reality enables designers and engineers to move around and

interact with the objects in real
-
time. The three
-
dimensional effect produced by Virtual
Reality techniques helps the system designer to easily understand the dynamics that are
taking place inside the simulated system. This paper would briefly discuss the

scope of
Virtual Reality in manufacturing, cite some practical examples where Virtual Reality is
used, and list out some of the benefits of Virtual Reality in computer
-
integrated
manufacturing (CIM).

K
EYWORDS

Virtual Reality, Simulation, Real
-
time, Comput
er
-
Integrated Manufacturing.


INTRODUCTION TO VIRT
UAL REALITY

Information technology has seen progress in leaps and bounds through the years. It
allows computers to transfer and access information within seconds. This efficiency in
data transfer has result
ed in the invention of many tools, of which ‘Virtual Reality’ is the
most prominent. Virtual Reality as the name suggests, is the closest man can get to reality
with his present capabilities.


Virtual Reality is a method by which a user visualizes, manipul
ates, and interacts with
computers and extremely complex data [8]. It is basically a computer
-
based technology
that gives learners a realistic, three dimensional and interactive experience. Using Virtual
Reality, users can interact within a computer
-
genera
ted environment, without much
technical training. Sherard [16] defines Virtual Reality as,


“The computer aided simulation of a three
-
dimensional model that one can interact
with in order to get a better sense of the project.”






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2


According to Burdea [1],


“Virtual Reality is a high
-
end user interface that involves real
-
time simulation and
interaction through multiple sensorial channels. These sensorial modalities are
visual, auditory, tactile, smell, taste, etc.”


Another important feature is that, Virtual

Reality allows operation in real
-
time that is
mandatory for several applications [19]. Real
-
time refers to the immediate response to
some event in a system, such as process completion, part arrivals or machine
breakdowns. Response would include selecting
parts for a machine, starting a machining
process, re
-
routing a part etc. [4]. Virtual Reality application becomes practical when
creating a simulated environment and is more economical than placing the user in the real
environment. Speaking of application
s, Virtual Reality is such an adaptable tool, that it
can be used in almost all fields. Its application ranges from home entertainment to high
tech space craft simulation. Currently Virtual Reality is used in fields such as
architecture, medicine, military
, etc., but the most prominent use seems to be in
manufacturing industries [16]. Thus, Virtual Reality is gradually coming out of research
labs and penetrating into the shop floor of an industry.

C
OMPONENTS OF
V
IRTUAL
R
EALITY SYSTEMS

There are wide varieti
es of components that make up the Virtual Reality system. The
most commonly used are the head mounted display and the data glove. Head mounted
display (HMD) is a helmet or a facemask that holds the visual and auditory displays. A
typical HMD houses two min
iature display screens and an optical system that channels
the images from the screen to the eyes, thereby presenting a stereo view of a virtual
world.

When the user wears the HMD, he can view the computer
-
generated virtual image.
Today, with the developme
nt of modern HMDs, a high degree of reality can be obtained.
Some examples of HMD are [1],



LCD based HMD (Liquid crystal display)



CRT based HMD (Cathode ray tube)



Binocular Omni
-
orientation monitors (BOOM)



Cyberscope



Stereo glasses

Figure 1.1 shows a simpl
e head mounted display.


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3






FIGURE

1.1

-

HTTP
://
WWW
-
VRL
.
UMICH
.
EDU
/
INTRO
.
HTML

Though HMD allows the user to view the objects in three
-
dimensional, it does not allow
him to interact with the objects present in the virtua
l world. Without interaction, the user
cannot get a feel of the object. To combat this, a data glove can be used. The user can see
the glove through the HMD in the form of a floating hand. Some examples of data gloves
include [1],



Cyber glove



Power glove



D
exterous hand master (DHM)

From the above description, it is clear that Virtual Reality is immersive, interactive and
imaginative and can be represented as shown below.
















F
IGURE
1.2



THREE

I’
S
(B
URD
EA ET AL
[1])

The other devices include keyboard, mouse, joystick etc. A voice recognition system is
also a good augmentation to Virtual Reality systems, especially when user’s hands are
being used for different tasks [8], [18].


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4


VIRTUAL REALITY AND
SIMULAT
ION

Recent computer technology has enhanced simulation to run within Virtual Reality
environments. Simulation and Virtual Reality are growing fields and more and more
industries are using these technologies in their operations. The major limitation of a
co
nventional simulation system is that, the developer and analyst need to have coincident
skills. Virtual Reality, primarily an interface technology eliminates the need for the
analyst to possess skills necessary to operate the simulation [6]. Virtual Realit
y can also
emulate the simulation conditions exactly and make the simulation look very real [9].

This reduces the cognitive load on the analyst and allows him to concentrate more on his
task. Virtual Reality makes the simulation user friendly and allows im
mediate viewing of
results in real
-
time. With the results obtained from simulation, the analyst can make the
necessary changes and re
-
run the simulation till he gets an optimal solution. So the
experiments no longer need to be restricted to the simulation
programmer. Analysts from
different fields will be able to use their appropriate skills and at the same time, interact
with each other in real
-
time to get optimal solution. With this background, let us now
discuss the role of Virtual Reality in manufacturi
ng.

VIRTUAL REALITY IN M
ANUFACTURING

In recent years, the use of high quality graphics and animation has been on the rise in the
manufacturing systems. The present two
-
dimensional image systems suffer from the
setback of containing only a limited number o
f viewpoints. To offset these, three
-
dimensional graphic tools can be used. However, three
-
dimensional graphic tools require
high computation and may not be available on personal computers running in real
-
time.

“Virtual Reality could be the solution, gener
ating the three
-
dimensional graphic in real
-
time, concurrently with simulation generation, allowing users to move around and
interact with the process in a natural and interactive manner” [5], [6], [7]. Manufacturing
industry is particularly well positione
d to take advantage of the recent emergence of
affordable VR systems based on standard workstations or PCs [2]. Most of the new
products today exist as computer
-
aided design (CAD) models from the early stages of the
design cycle. Virtual Reality becomes ex
tremely powerful when combined with CAD. It
allows engineers and designers to view, manipulate, and modify complex designs. Virtual

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5


Reality is capable of presenting a realistic interface to a complex engineering model. For
example, if a user wants to handl
e and rotate a model, he can simply reach out, grasp the
object and twist his hand. Alternatively, he can also walk around the object to get a
different viewpoint.

V
IRTUAL DESIGN AND PR
OTOTYPING

In practice, the product is designed first and then the prot
otype is built. Prototyping is
done, so as to check the characteristics of the products under various conditions. The
product design is approved for manufacturing only if the prototype performs well. The
primary disadvantage associated with physical protot
ypes is that, they cost too much and
also consume a considerable amount of time in their development. Due to these
drawbacks, many innovative products were stopped from coming into the market even
before the design stage was completed.

In order to overcome

the difficulties in building a physical prototype, manufacturers have
begun to use Virtual Reality. Developing a ‘virtual prototype’ will cost only a fraction of
what a physical prototype would have [3]. Virtual prototypes help in the integration of
desig
n and manufacturing personnel to ensure that engineering designs are producible.
Virtual prototyping not only simulates the way things look, but also simulates the way
things work.

Being immersed in a virtual design environment, engineers can create and mo
dify
potential designs in real
-
time, seeing the effects of their modifications and changes
immediately. Also the user can explore the geometries, relationships, and movements of
objects in three
-
dimensional spaces in an almost realistic way, as if the part

were
physically there [3].

Caterpillar Inc. that produces heavy equipment such as wheel loaders and backhoe
loaders use a Virtual Reality system known as the ‘CAVE’ developed by the University
of Illinois, Chicago. Earlier, Caterpillar used three
-
dimensio
nal programs, which did not
allow viewing of product from all sorts of angles. The new system which they are
currently using, allows product designers to go through many more iterations and
revisions than before, when the physical prototypes had to be buil
t before customers got
their first look at new product designs [13]. Boeing, with the help of Virtual Reality
created a virtual prototype model for its new aircraft Boeing 777. Virtual prototyping

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6


allows pilots and designers to test how well the new compon
ents work. Chrysler
Corporation, the automobile manufacturers use Virtual Reality for testing the interior of a
car. The user sitting in front of an actual steering wheel wears a head
-
mounted display to
view the virtual interior of the car. With the help o
f a wired glove, the user can turn on a
virtual radio or honk a virtual horn [16]. The above mentioned were some of the potential
applications of Virtual Reality systems in design and prototyping. There are many other
industries that use Virtual Reality fo
r similar purposes.


V
IRTUAL ASSEMBLY
P
LANNING

The assembly of extremely complex products, such as aircraft and electromechanical
products are difficult to automate, as the high demand dexterity required for assembling
them, are not easily achieved by robo
ts. Also, complex products may have many small
parts and reprogramming robots for these quantities is an expensive prospect. The
concept of virtual assembly planning can be used in such cases. Virtual Reality provides
an excellent environment for the clear

observation of assembly experts at work. As the
experts work, the movements of both the user and the components can be recorded by the
system. Once the user completes assembling the parts to his or her satisfaction, an
assembly plan can be automatically g
enerated from the stored usage data. One major
criticism in using Virtual Reality in assembly is that the virtual systems lack the sense of
touch i.e., the user cannot feel the object. The sense of touch is extremely important for
precise positioning of pa
rts during the assembly process. However, to overcome this
problem, two new methods called the “collision snapping” and “proximity snapping”
positioning have been developed. The explanation of these methods is beyond the scope
of this paper. However, a det
ailed discussion about these is found in the article by
Carpenter et al [2]. These techniques are analogous to the snapping methods used in CAD
systems.

Ford Motor Company uses Virtual Reality for automotive assembly. The vehicle parts are
represented in
a CAD system. The CAD file is then transferred to the system with Virtual
Reality equipment. A user manipulates the virtual part in real
-
time and attempts to
assemble it into a virtual vehicle. Also, the concept of networked virtual environment
enables col
leagues located at different sites to work together on design projects in some

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7


virtual space and perform real
-
time simulation of assembly and manufacturing processes
[13].

VIRTUAL CORPORATIONS

Large and multinational manufacturing companies have their vari
ous departments
dispersed at different geographic locations. For example, a company might have its
design team in United States of America and its manufacturing plant in Australia.
Moreover, the customers are spread throughout the world. In such cases, it
becomes
difficult for the departments to communicate with each other and make quick decisions.


Virtual Reality could be used to bridge the gap between various departments involved in
the development of a product, thus saving valuable time and also the mon
ey spent on
travel. The above can be accomplished by using a shared environment, an extension of
the idea of teleconferencing. One such potential application could be the design of plant
layout for a new factory where architects, mechanics, and control eng
ineers can all work
in the same virtual environment without necessarily being in the same location. By using
each one’s particular skills and objectives, the issues like optimal scheduling, efficient
plant layout, maintenance and accessibility can be addre
ssed taking into consideration the
range of design and ergonomic factors. The actual operation of the factory could be
simulated and the results could be observed and analyzed. Virtual Reality applications
may have multiple simulations running on different

machines and the results produced
could be coordinated with the help of a simulation engine to represent a complex task [8],
[17]. Teleconferencing is a method of conducting discussion and research globally by
using Internet as the medium. This eliminates

the need for travel costs and organizing
specific meetings [15].


For example, Ford Motor Company has taken the initiative to incorporate Virtual Reality
in its manufacturing process. It has assigned a team in its FORD 2000 project to work on
the design o
f a car in such a way that the designers are physically at a different place,
whereas the manufacturing occurs somewhere else. All the individual parties must be
able to see, modify, and interact with the design in real
-
time to achieve optimality in
design

in accordance with the manufacturing constraints. Figure 5.1 shows two

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geographically separated users sharing information about a product model in a virtual
environment.








Shared information

















F
IGURE
5.1



(R
AGUSA ET AL
[14])

VIRTUAL REALITY SOFT
WARE SYSTEMS

University of Sheffield was involved in the development of three
software packages
namely SWOOP (Simulation with Object
-
Oriented Programming) for simulating discrete
and continuos systems, VROOM (Virtual Reality using Object
-
Oriented Methods) for
designing Virtual Reality environments that can run on any 386 PC with a V
GA card, and
SWOOPVR that has both the capabilities of SWOOP and VROOM. Models developed
using SWOOPVR can respond to instantaneous changes and make motion look more
Product

Model


Virtual Environment

Information Interests

Perspective

Virtual Environment

Information Interests

Perspective

User

User


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9


natural and realistic. The user can move through the simulated process and can view the
mo
del dynamics with the press of hot keys or with the help of any input devices. The
object
-
oriented structure present in SWOOPVR enables virtual prototyping to be done
more effectively. To illustrate the capabilities of this software, various virtual protot
yping
applications were modeled using this software [5], [6], [7].

The software that has won several awards is the World Tool Kit (WTK) developed by
Sense8 Inc [8]. It can run on a variety of platforms and can link the virtua
l world to the
data in real
-
time. Thus the user can interact with the virtual world and interact with the
objects present in the real world. There are also other software packages available for
developing Virtual Reality systems. These are of great help to

the manufacturing
industries for developing virtual prototypes. To know more about the available Virtual
Reality software systems, refer to the article by Teschler et al, 1995 [18]

BENEFITS OF VIRTUAL
REALITY IN CIM

Computer
-
Integrated Manufacturing (CIM)

is defined as,

“Systems which enable the integrated, rationalized design, development,
implementation, operation and improvement of production facilities and their output
over the life cycle of the product. These systems identify and use appropriate
techn
ology to achieve their goals at minimum cost and effort” [12].


There are four stages in a product life cycle in a CIM environment. They are conceptual
design, detailed design prototyping, manufacturing and product usage and disposal.
Among these stages, t
he design stage is the most critical as it sets the stage for product
success or failure in the market place. The reason is that, product design has a direct
impact on product cost, quality, and reliability. Typically 80% of the cost of a product is
fixed
at the design stage (Dransfield, 1994) [11].

Virtual Reality can play a crucial role in the design and prototyping process. Building a
physical prototype consumes more time and also is expensive. Developing a virtual
prototype will cost only a fraction of
what a physical prototype would have [3]. With the
help of devices like head mounted displays and data gloves, the designer can view and
interact with the virtual prototype of the model. By this he can make necessary
modifications to the design and also st
udy their behavior by simulation. Design problems
can be easily rectified and the product is taken for manufacturing. Evan Andricopoulos, a
project engineer at ARDEC says,


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10


“A Virtual Reality system allows a user to interact with a design during its
develop
ment phase, side by side with an engineer, and make design evaluation that
can be implemented quickly with zero cost impact” [15].


Market share and profitability are the major determinants of the success of any
organization. The cornerstone of increased m
arket share and profitability is the edge an
industry has over its competitors. Concurrent engineering has emerged as a discipline to
help achieve the objectives of reduced cost, better quality, and improved delivery
performance [11]. The U.S Institute of
Defense has defined concurrent engineering as
follows:

“Concurrent Engineering is a systematic approach to the integrated, concurrent
design of products and their related processes, including manufacture and support.
This approach is intended to cause the
developers, from the outset, to consider all
elements of the product life cycle from conception to disposal, including quality,
cost, schedule, and user requirements. (Pennell and Winner, 1989)”


Fostering communication is an important aspect in computer
-
i
ntegrated manufacturing
systems. One of the greatest benefits of Virtual Reality is that, it serves as a
communication tool that will assist concurrent engineering teams in exploring all aspects
of a design [16].


Flexible manufacturing system (FMS) is an
important application of CIM. FMS is an
automated, midvolume, midvariety, central computer controlled manufacturing system.
One of the essential physical components of the FMS is the Automated guided vehicle
system (AGVS). An AGVS is a battery
-
powered driv
erless vehicle with programming
capabilities for destination, path selection, and positioning [11]. However, implementing
automated guided vehicle system is an expensive investment and hence has to be proven
worthy. Virtual Reality can be used to test the
performance of AGVS by three
-
dimensional discrete
-
event simulation [3]. From this test, it is possible to decide whether
or not to implement an AGVS. Virtual Reality could also benefit industrial robotics
through robot design, environment modeling, off
-
lin
e programming and teleoperation.


Thus, Virtual Reality when combined with simulation tools can reduce design and
production costs, ensure product quality, and reduce the time required to go from product
concept to production, while being highly responsive

to continually changing market and
world condition.


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11


RESEARCH ISSUES

Though Virtual Reality has many applications in the field of manufacturing, it is yet to be
fully exploited by the industries. Many research issues need to be resolved before it can
be fu
lly operational. Some of the research issues are [14],

L
IMITATIONS OF CAD

Current computer aided design (CAD) technologies do not fully support concurrent user
operations in either a stand
-
alone or networked mode, and moreover variable perspectives
are not

yet possible. Considerable amount of Research & Development remains to be
accomplished and many user issues need to be addressed.

N
ETWORK COMMUNICATION
S

While great strides are being made, present network technologies and capabilities would
only marginall
y support the throughput requirements of distributed CAD and Virtual
Reality concurrent design environments.

L
IMITATIONS OF
V
IRTUAL
R
EALITY TECHNOLOGY

Virtual Reality technology does not have the potential to handle the networked,
interactive needs of a di
stributed real
-
time design system. In addition a basic premise, yet
to be validated, is to determine if visualization techniques significantly clarify shared
information and improve decision making by multiple team members working in an
interactive environ
ment.

H
UMAN AND ORGANIZATIO
NAL BEHAVIOR

There is a number of human and organizational issues which must be better understood if
Virtual Reality based manufacturing has to be implemented. The use of technology,
regardless of its promise, does not guarantee
that humans working in a virtual
environment will perform better than those using present systems will.

C
OST EFFICIENCY

Whatever systems are developed, positive cost
-
benefit will be an important part of the
determination of industrial use of Virtual Realit
y.


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12


CONCLUSIONS

In this paper, some of the potential application areas of Virtual Reality in CIM have been
discussed and some practical examples where Virtual Reality is used have been outlined.
Virtual Reality, when properly implemented can offer many adva
ntages to manufacturing
industries. It could enable manufacturers to reduce costs, reduce manufacturing lead
-
time
and improve product quality. Inspite of this, Virtual Reality is not exploited by many of
the industries due to certain limitations. Numerous
research issues and technical
challenges remain.

“Virtual Reality is not something that an average user will have this year or next year,”
says Larson
-
Mogal. “There is lot of work still to be done both in the technology and in
the software before it is goi
ng to be broadly available and usable” [15]. This gives us
more optimism regarding the scope of Virtual Reality in manufacturing, as we see that it
is highly powerful even when not fully explored and developed.















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13


BIBLIOGRAPHY

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d P. Coiffet,
Virtual Reality Technology
, John Wiley & Sons, Inc.,
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[2] Carpenter, I.D., Ritchie, J.M., Dewar, R.G., and J.E.L. Simmons,
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Manufacturing Engineers, IEE, UK, 76, pp.113
-
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Manufacturing Engineers, IEE, UK, 75,
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