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Augmented reality as a design tool for mobile interfaces
Olav W. Bertelsen & Christina Nielsen
University of Aarhus
Department of Computer Science
Aabogade 34, DK-8200 Århus N. Denmark
+45 89 42 31 88
{olavb | sorsha}@daimi.au.dk
ABSTRACT
This paper challenges user interface paradigms for mobile
devices, by using the technical classification of augmented
reality interfaces as a ‘thinking tool’ to develop ideas for
interaction with mobile devices. The paper presents future
work scenarios from a wastewater treatment plant
embodying PDA applications derived from the classification
of augmented reality interfaces. The focus on physical
interaction with objects of work and with the mobile device
provides us with a range of interaction styles, based on e.g.
gestures and manipulation of objects. Furthermore, issues
of transparency and directness are addressed. The future
scenarios indicate that the concepts of augmented reality
support solving context problems in mobile design.
Keywords
Thinking tools, augmented reality, mobile computing,
process control.
INTRODUCTION
It is widely acknowledged in the field of mobile computing
that there is a need for new interaction paradigms [5, 7, 12,
9]. Solving this problem requires insights from a broad
range of disciplines, including distributed systems, HCI,
CSCW and participatory design [5]. Established concepts in
desktop computing are not scaleable. E.g., the concept of
direct manipulation that historically has served as the main
vehicle for understanding the graphical workstation is not
applicable in the design of small mobile devices [9]. This
difficulty is due to the tunnel vision imposed by, otherwise
valuable, established cultural norms like the desktop
metaphor, the workstation concept, and the general thinking
in terms of database access.
Augmented reality is an approach to information systems
design augmenting physical objects instead of replacing or
representing them by purely computer based systems. The
argument is that non-computer based artefacts in the
workplace often mediate work in subtle ways that are
impossible to transfer to new computer based artefacts [10].
In a work-oriented terminology [4, 14], augmentation can
be understood as a basic feature of human action in the
sense that human action always is mediated by historically
developed artefacts which are invisible during use.
Augmentation and augmented reality can be seen as a
general attitude to design, realised through refinement of
mediating artefacts, acknowledging the historical
crystallisation of work into successive generations of
artefacts [1, 2].
Mackay [10] introduces augmented reality as a classification
of three technical approaches to design of interactive
devices, spanning a continuum of technical substrates for
mixed environments: augmenting the user, the physical
object and the environment (see Table 1 below). These
strategies describe the technical locus of the interface
assuming the analytical separation of function and
interaction in the computer artefact. From the work-oriented
point of view, introducing a new artefact is always a matter
of augmenting the acting subject.
In this paper, we explore new interface principles for small
mobile devices derived from the concept of augmented
reality interfaces. We use the concept as a tool for divergent
thinking, in line with the use of metaphors in participatory
design [11], and springboards in developmental work
research [6]. By definition, the concept of augmented reality
cannot be applied to small mobile devices; thus we abstract
defining features from the three directions in augmented
reality interfaces and apply them in the different technical
setting. Subsequently, the principles are further investigated
through future scenarios of PDA support for wastewater
treatment work built on the augmented reality classification
transformed to small mobile interfaces.
AUGMENTED REALITY IN A PDA
In applying the concept of augmented reality as a thinking
tool for the design of mobile artefacts, the specific technical
substrates in which augmented reality interfaces are
implemented are bracketed out. What we hold on to is the
principle of interaction with or through physical objects
(already existing) in the work setting. Below, we explore
the three directions in augmented reality interfaces described
by Mackay [10]. We use this classification to develop
metaphors for mobile applications not based on the idea
that the PDA is miniature workstation.
Published in: Proceedings of the Third Conference on
Designing Interactive Systems (DIS 2000), D. Boyarski &
W.A. Kellogg (Eds.), ACM ISBN: 1-58113-219-0, 2000, pp.
185 - 192.
Augmenting the user
The strategy of augmenting the user means that the
interface to the computer system is attached to the user as
e.g. VR helmets, goggles or data gloves. When
implemented in a PDA, this strategy is transformed to
applications where the PDA is physically attached to the
user (possibly hand held). The PDA functions as "glasses"
extending the users perceptual capabilities in (into) the
domain (work object), and as "gloves" extending the users
capabilities in acting onto the domain. Interaction may be
carried out through gestures performed holding the PDA.
Because the PDA acts as an extension to the user, the
connection between PDA and object is hidden and indirect.
Within this strategy, we may include context specific access
to a more general information system.
The augmenting the user approach to PDA design could
lead to applications resembling a well-designed remote
control for a TV set. The remote control is in the TV
viewing situation a transparent, almost invisible, extension
of the viewer. The viewer manipulates the TV-set directly
through gestures with the remote control. This sense of
direct manipulation is obtained through the layout and
shapes of the buttons.
Another existing example is the way wireless controls of
lifts are attached to the worker operating the machine from a
distance.
Augmenting the object
The strategy of augmenting the object means that the
interface to the computer system is attached to, or embedded
in the object. When implemented in a PDA, this strategy is
transformed to applications where the PDA is provisionally
attached to the object. Interaction with the PDA (or the
wider information system) is carried out through
manipulation of the physical object to which the PDA is
attached, and through showing information on the object by
way of the PDA display. Thus, the PDA augmenting the
object, turns the physical object into an interaction device
and at the same time makes the object more accessible for
the user.
Because the PDA becomes embedded in, or rather attached
to, the object, the connection between the PDA and the
object is visible and direct.
The augmenting the object approach to PDA design could
lead to applications resembling the help and guidance
system in many modern photocopiers. When a
compartment is open, the display on the copier indicates
which one and points to its physical location. In case of a
paper jam, the computer system guides the user through a
sequence of physical actions triggered by the user
manipulating e.g. hatches in different areas of the machine.
Another approach based on augmenting the object could be
to take the idea of augmented paper [10] to the extreme by
simply substituting existing notepads with a PDA based
application. Obviously, this is not augmented reality in any
strict sense of the concept.
Augmenting the environment
The strategy of augmenting the environment means that the
interface to the computer system is embedded in the
environment surrounding users and objects, projecting
images and recording remotely. When implemented in a
PDA, this strategy is transformed to applications where the
PDA is provisionally placed in the environment of the
work situation. Interaction with the PDA (or the wider
information system) is carried out through manipulation of
the physical objects that are tracked, by means of
technologies in a continuum from bar code readers to
cameras with image recognition build into the PDA, and
through projecting information onto the object. For the
latter, a lot of development of basic technology is required
— although more realistic, low cost solutions are being
developed, e.g. the Gesture Laser [15].
Because both user action and objects have to be tracked, and
images ideally should be projected onto objects, this
strategy is the most demanding to implement.
The augmenting the environment approach to PDA design
could lead to applications resembling the set-up at a
workstation at an assembly line, where
mechanical/electronic devices are assembled. Such devices
Augment Approach Technology Application
User Wear devices on the body VR helmets Goggles Data
gloves
Medicine,
Field service, Presentations
Physical Object Embed devices in objects Intelligent bricks, Sensors,
receptors, GPS, electronic
paper
Education,
office facilities, Positioning
Environment surrounding
objects and users
Project images and record
remotely
Video cameras, Scanners,
Graphics tablets, Bar code
readers, Video projectors.
Office work, Film-making,
Construction, Architecture
Table 1. Examples of augmented reality interfaces, with relevant technologies and applications (adopted
from Mackay 1998).
typically consist of a number of printed circuits, connectors
and shielding. The assembly is done by hand and requires
different electronic circuits depending on the type of device.
At a specific workstation for assembling flow meters we
have seen that, to aid the assembly procedure, each primary
component (not including screws, bolts and nuts) is
equipped with a bar code, which must be entered into the
computer responsible for testing the assembled product. The
assembly procedure cannot be completed until all primary
components have been entered into the system, and the
computer clearly indicates if wrong components have been
scanned. In a sense, the computer is tracking the physical
objects required for a specific flow meter and even though,
it has no direct, online connection to the components, e.g.
through sensors.
EXPLORING THE THREE STRATEGIES
During the past year, we have been engaged in a study of
wastewater treatment plants. Wastewater treatment is a low
risk process running continuously day and night. Work in
the plant is distributed to a degree where it seems to go on
elsewhere, no matter where you look. People working on
the plant have two general modes of relating to the plant
and the process. Totally mediated, i.e. through the process
control system or totally unmediated, by looking at and
smelling the water. The workers do not seem to have one
favourite tool; e.g. illustrated by one of the workers making
a sludge sample in a used plastic glove and stirring the
sample with a pen. For a more detailed description of the
project and the study, see (Bertelsen & Nielsen 1999).
In order to develop further the interface principles derived
from the concepts and classification of augmented reality,
we develop scenarios for support of situations in the
wastewater treatment plant. The scenarios are based on
applications for a standard PDA, in this case a 3Com Palm
Pilot IIIx.
Additional features to be built into the PDA are held to a
minimum and are as far as possible taken to be the same
across the future scenarios. That is to emphasise our focus,
namely the new interaction principles for the PDA rather
than futuristic gadgetry. Thus the way the PDA is
interfacing with the environment is limited to the standard
infra red port, a bar code reader, a standard cell phone and a
modem.
Augmenting the user
In implementing the principle of augmenting the user in a
PDA supporting work in a wastewater treatment plant, we
take the simple approach of the remote control. We use one
of the more peculiar situations we observed in our field
study, a repair situation, as our example/template to
illustrate and develop the approach.
The situation was a case of simple repair work. A wire
operating the scrapers in one of the clarifier tanks was
broken, causing the tank to shut down automatically. A
team of blacksmiths' was called in to fix the problem. As
part of the repair, it was necessary to operate the winch.
The winch motor was, however, only controllable from a
terminal in the central control room. Thus, the smith had to
make a telephone call to the central control room which,
incidentally, was occupied by a worker, and ask him to start
the motor. Unfortunately, this had no effect on the motor.
The worker in the control room suspected a failure in the
process control system and called the foreman, who was
working outside the plant that day, to let him know about
the problem with the system. The foreman explained that
the winch usually gets stuck if it gets into one of the
extreme positions. He asked the worker to tell the smith to
call him on the telephone so that he could guide him
through releasing the wire. The worker in the control room
was now waiting for the smith to call and tell him to start
the motor again, but nothing happened until the smith
called to inform him that he was done with the repair. In
addition to the information on how to unblock the wire, the
foreman had explained to the smith how to short circuit a
few cables in the motor to bypass the central control of the
motor locally.
Figure 1: Blacksmith fixing a broken wire in a
clarifier tank
By centralising and co-ordinating control of individual
component, the process control system ensures that
interdependencies are not violated. Mobile control is a
highly problematic possibility to integrate into a process
control system in that it may violate the purpose of having
a process control. However, the situation with the broken
wire illustrates the dilemma inherent with centralised
control. Either the smith would be on the telephone with
somebody in the control room (which is what happens over
and over again in all the wastewater treatment plants our
collages and we have studied), or he would "hack" the
control system, which would be a potential security
problem. The challenge is to find a solution that maintain
the consistency and security of local control, without
imposing cumbersome procedures that invites the operators
to bypass parts of the system.
This challenge is addressed by the following future scenario
with a PDA-application based on the augmenting the user
strategy. The "standard PDA" is extended with a bar code
reader and a modem for the cellular telephone the smith is
carrying anyway. During repair of the wire, when the smith
needs to operate the winch he reads the bar code on the
winch and calls up the process control system through the
telephone. Together with the identification of the particular
component, the smith is working with the PDA sends
identification of the smith. Thus, the process control
system has information enough to determine which kind of
access the smith needs to the component. The process
control system returns a list of the parameters the smith can
access, in the case of the winch, start, stop, reverse and
frequency of the motor, and it suggest a binding of the
parameters to standard PDA key. Now, the smith can start,
stop and reverse the motor through the up/down scroll
button on his own PDA. The overall system consistency is
maintained by only letting the smith control locally task
and location specific parameters.
This application augments the smith in interacting directly
with the motor in a gesturelike fashion. In the work-
oriented terminology introduced above, this means that the
PDA is handled through unconscious, automated operations
(scrolling up and down).
It transcends the local control versus system consistency
problem by letting the user interact directly on the relevant
component through his own interaction device, but still
letting the process control system inhibit dangerous
violations of interdependencies in the system.
The PDA screen shown in figure 2 is designed for a Palm
Pilot. However, an implementation with WAP technology,
would probably prove even more suitable.
Figure 2: Display from a PDA application based
on the augmenting the user strategy
Augmenting the object
In implementing the principle of augmenting the object in
a PDA application supporting work in a wastewater
treatment plant we develop two future scenarios. The first
scenario is based on the photocopier example above in the
sense that it supplies local display and control, the second
is based on the concept of augmented paper.
Local display and control
The first future scenario build on the augmenting the object
strategy is derived from the photocopier control display
example above. It addresses the lack of local display and
control in newer generations of frequency converters
A wastewater treatment plant is equipped with a large
number of electrical motors most of which are driven by
alternating current. To regulate the speed of such a motor
the frequency of the power supply must be regulated by
means of a frequency converter.
Figure 3: An array of frequency converters
Contrary to the newer models, older frequency converters are
often equipped with a small display and controls for
operating it directly. The lack of local control and display in
the newer models is not a problem; in most situations, it is
controlled from a process control system. However, in the
occasional situations of breakdown, calibration,
maintenance, etc., local control of the unit is needed.
This occasional access to direct operation of the frequency
converter can be obtained with a PDA based application
augmenting the object, in this case the frequency converter
(see figure 4).
The wastewater worker or the external specialist who needs
local control of the frequency converter reads the bar code on
the unit and attach the PDA and cell phone to the housing.
Now, the PDA calls up the process control system through
the cell telephone modem, and "negotiates" the amount of
control of the frequency converter that can be given locally.
Upon initialisation, the controls on the new PDA-based
local interface consist of the subset of control over the
frequency converter it makes sense to have locally,
depending on who the person is, which dependencies there
are in the actual state of the plant, and the purpose of
working on the PDA. Some of these aspects may have been
decided beforehand and entered into the process control
system centrally.
The frequency converter is augmented with the interface of
the PDA that during the situation becomes a part of the
component rather than a personal digital assistant. The
advantage of this scenario over the direct local control is
that dependencies in the plant are not violated by the users'
local control. In general, mobile control of process control
systems is considered problematic. In this scenario, the
dangers are avoided through strong context specificity of
control. The cost of the scenario is low because the
wastewater treatment plant is extensively wired to the
process control system.
Figure 4: Display from a PDA application based
on the local display and control version of the
augmenting the object strategy
Augmented paper
The second future scenario exploring the principle of
augmenting the object as a principle in PDA support for
wastewater treatment work is based on the concept of
augmented paper.
Each day, one of the workers reads the meters related to the
production of electricity at the plant. The worker notes the
numbers on a protocol sheet, take all the numbers to a note
pad on a table performs some calculations, and writes the
numbers in a paper record. Finally, he carries some of the
numbers on a scrap of paper to the house where the
computer is located; there he inputs data to the process
control system.
Our study of wastewater treatment work indicated the
importance of several hand-written paper records for test
results as well as for the gas and electricity production.
These records, however, were also input to the Process
control system and therefore the object of rewriting two or
three times. This led to discussions of whether the rewriting
was a necessary evil caused by the lack of technological
support or whether it in fact served other purposes than
simply transferring the numbers from one medium to
another. To test this hypothesis, we implemented a
prototype for an augmented paper record based on the
CrossPad technology. The CrossPad was trained to read and
recognise the hand-written record and propagate/transfer it
the computer system. We set up a scenario where the
CrossPad served as a mobile link between the meters and
the Process control system, rendering the rewriting obsolete
but retaining the paper record. When we presented this
solution to workers and managers at the wastewater
treatment plant, it was refused. To them, there was no point
in hanging on to the paper records if it was possible to
solve the authentication issue in another way. Furthermore,
they did not believe that rewriting numbers guaranteed that
workers actually think about the numbers.
Figure 5: Wastewater operator reading the gas
meters
The radical application, based on the augmenting the object
strategy, of support for reading the electricity production
related meters eliminates the former object and replaces it
with the PDA. In the meter-room, the worker reads the bar
code on the desk for the PDA to invoke the electricity and
gas production record. As he reads the meters, he writes the
reading on the number-pad on the PDA screen. Upon
reading the meters, the PDA calculate the results and
present the worker with the results together with the results
from the previous day. The worker leaves the meter-room
and goes to the central control room where he "beams" the
results into the process control system by way of the infra
red port build into the PDA. This application could as well
be classified as augmenting the user.
The PDA would ideally have a number keypad, but for the
sake of consistency across examples, we keep with the
standard PDA (see figure 6). Again, a WAP based approach
is an elegant alternative.
Figure 6: Display from a PDA application based
on the local augmented paper version of the
augmenting the object strategy
Augmenting the environment
In implementing the principle of augmenting the
environment in a PDA supporting work in a wastewater
treatment plant, we take the simple approach of the
assembly station, and use it as the basis for the design of an
automatic, context sensitive on-line manual.
A wastewater treatment plant is a complex technical
system. Becoming familiar with the technical system is not
done overnight but is a yearlong learning process. The
scope of the task has been very aptly put by one of the
unskilled workers at the studied wastewater treatment plant:
"I have been working on this plant for four years and am
starting to ‘know’ the plant, but I think it will take another
two years before I know it well enough – where all the
machines are, etc. For example, we have pipes running
through this building and they are normally working fine so
you can basically work here for years without knowing
there’s a (throttle) valve up there [pointing]" (..) You never
find out before something happens (..) We work with
50.000 components – you don’t learn about them on your
first day”.
One of the responsibilities of this specific worker is to
mind an array of motors producing electricity from gas
produced from sludge in the plant. Maintenance of the gas
motors is divided between workers at the plant, the
municipal blacksmith department, and technicians from the
manufacturer. Minor repair and maintenance tasks performed
by one of the unskilled workers are coordinated with major
repair, inspection and maintenance, in order to reduce down
time. One of the frequent tasks is the cleaning and
adjustment of spark plugs in the motor.
Figure 7: The gas motors
The principle of augmenting the environment through the
PDA may be implemented to aid this assignment in the
following manner. The wastewater treatment worker enters
the area with the gas motors and starts the procedure by
turning off the relevant motor manually. He then scans the
bar code on the motor with his PDA, connects to the
process control system through the mobile phone attached
to it and checks on it that the shut down has been
acknowledged there. He places the PDA on a shelf next to
the motor so the display is visible from his current
position. The PDA displays a simple blueprint-type
drawing of the motor, highlighting the front panel, and a
short textual description of how to remove it (see figure 8).
After having removed the front panel he runs its bar code
past the scanner on the PDA; the display changes to show
the next step of the disassembly procedure. In this manner,
he works his way into the motor to the spark plugs. The
PDA presents instructions in which order to remove and
replace the spark plugs, triggered by scanning the individual
units. He then acknowledges on the PDA that no more
motor components will need replacement, and is now
guided through the procedure of reassembling it, scanning
the components in reverse order. For users experienced with
a specific type of motor and task, the online manual serves
only as a peripheral guide with the purpose of making sure
the relevant motor components are removed and (in
particular) re-inserted. For novice users, the online manual
may serve as a component specific, context dependent
learning guide.
This future scenario illustrates how we may support the
vast learning task involved in maintaining the multitude of
components in this wired wilderness through externalising
the relevant information through the PDA.
A far more elegant solution, but far from realistic today, for
this application would be to embed a camera with effective
pattern recognition features to seamlessly do what the
worker in the example has to do by hand and bar code
reader.
Figure 8: Display from a PDA application based
on the augmenting the environment strategy
DISCUSSION
We have presented future scenarios for wastewater treatment
work with PDA applications developed by using the
technical classification of augmented reality interfaces as a
thinking tool. The applications in these scenarios are
designed for a standard PDA extended with a bar code reader
and a modem for a cellular telephone. Thus, we have been
emphasising solutions that can be implemented with
limited resources today. The use of bar codes is clumsy, but
has the advantage of being cheap, and making the choice of
context totally explicit. In this respect, our contribution is
in radical contrast to achievements like the Cy-Phone,
which is an all-purpose personal tool based on Pico Cells
[13]. Our future scenarios address some of the specifics of
wastewater treatment work: the distributedness, the number
of different component the workers have to deal with, the
wired wilderness enabling most of the designs. In a setting
with a lower degree of interdependency and "wiredness",
PDA support might be different. However, the principle of
designing PDA applications as augmentation of the user,
physical objects or the environment is likely to be
applicable in a broader context.
The applications in the four future scenarios have been
developed into horizontal prototypes, i.e. screen layouts
with no underlying functionality. In general horizontal
prototypes and mock-ups are suitable means of testing
design ideas with users. However, in this particular case, we
believe that some amount of functionality and integration
with the process control system is needed investigate into
the ideas beyond the level waving our arms. This is an
obvious problem because outside interaction with a control
system can have dangerous effects, and because it requires
access to the control system software.
Using the concept of augmentation and the classification of
augmented reality interfaces as a thinking tool gave us
several advantages. Using the augmented reality principles
as thinking tools sparked our imagination and at the some
time steered us clear of pure science fiction.
Initially, the concept "augmented reality" seemed to be
impossible to apply in PDA design; it seemed that a PDA
application would always end up being based on the
"augmenting the user" class of interfaces. This apparent
impossibility turned out to be an important source of
creativity. This technique is generally applicable. That is,
when established design principles impose tunnel vision on
designers, proceed by selecting technical concepts that
obviously not fit the design problem, and then structuring
the new solutions according to the misfit concepts.
We saw that the classification of augmented reality
interfaces seemed to blur when applied to PDA design.
However, taking the second scenario as an example, even if
the PDA based record looks like an augmentation of the
user the design is still based on automating and augmenting
the paper based record. This seeming confusion is due to
augmented reality being a pragmatic technical classification
of a class of interfaces technologies.
Focussing on interaction with physical objects in the work
setting provided us with specific boundaries to work within
and thus became an effective guide in deciding what to
include in each of the PDA applications. Thus, the concepts
of augmented reality worked as a tool for handling the
context problem. Most of the information and control made
accessible with the suggested PDA applications is present
in the existing process control system. The strong focus on
interaction with physical objects around the plant, however,
helped in specifying actual physical and situational context
for the applications in the future scenarios.
The three different strategies of augmenting the user the
object and the environment enabled us to transcend the
image of interaction with a PDA as the users introvert
fiddling with his little pen on his personal four square inch
pad. Through our future scenarios, a broader range of
physical postures in interaction with a PDA emerged: hand
waving, writing, walking around, etc. The original
formulation of augmented reality was primarily a concept of
interface technology, the way we have used it in this paper
turns it into an interaction style concept. Thus, augmented
reality may be abstracted into interaction concept
independent of the concrete technical substrate of
implementation.
As stated in the introduction, direct manipulation as a
general user interface principle falls short in relation to
mobile devices. In particular the lack of screen space
inhibits detailed representation of the object of work at the
screen. Basing PDA design on concepts of augmented
reality interfaces, forced us to think beyond direct
manipulation; it simply does not make sense to represent
the object of work naturalistically on the screen if it is
physically present in the situation of work. However, as
illustrated in our future scenarios, principles of direct
manipulation interfaces, e.g. directness and transparency,
apply nicely for mobile devices just as well as for full-
fledged augmented reality systems.
ACKNOWLEDGMENTS
We thank the people at the wastewater treatment plant for
their time and effort. Susanne Bødker, Wendy Mackay,
Astrid Søndergaard and Christian Yndigegn have all been a
great inspiration in the wastewater project. Christian
Yndigegn programmed the augmented paper prototype for
the CrossPad. We acknowledge the effort of the people at
Danfoss and at Malmö University College. The Danish
Basic Research Foundation, Centre for Human-Machine
Interaction and The Danish National Centre for IT-Research,
project no. 23 (Usability Work in the Danish Industry) have
supported our work on the wastewater project.
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