current flowing through a circuit breaker exceeds its maximum ... the line current and the breaker settings may cause .... are color coded to match the colors of the.
/N--s/ NASA
Technical
AIAA-93-4657
Memorandum
106412
7F
i
Design and Implementation of a Status at a Glance User Interface for a Power Distribution
Expert
Eugene M. Liberman and David Sverdrup Technology, Inc. Lewis Research Center Group Brook Park, Ohio
System
B. Manner
and James
L. Dolce and Pamela
A. Mellor
National A eronautics and Space Administration Lewis Research Center Cleveland,
Ohio
Prepared for the AIAA: Computing in Aerospace 9 sponsored by American Institute of Aeronautics San Diego, California, October 19-21, 1993
and Astronautics
N94-21589 .......................
(NASA-TM-106412) DESIGN AND IMPLEMENTATION OF A STATUS AT A GLANCE USER INTERFACE FOR A POWER DISTRIBUTION EXPERT SYSTEM (NASA)
Unclas
7 p G3131
OlqBO/B
:
DESIGN AND IMPLEMENTATION OF A STATUS AT A GLANCE USER INTERFACE FOR A POWER DISTRIBUTION EXPERT SYSTEM
Eugene
M. Liberman
and David
B. Manner
James
Sverdrup Technology, Inc. Lewis Research Center Group Brook Park, Ohio 44142
National
L. Dolce
and
fault
features
are widely used in health monitoring
detection
applications. system
of knowledge
it was designed.
knowledge
base,
system's
it
reasoning as possible.
is part
of a process
system's
is difficult
require
attention.
integrate
expert
and
to focus
matters
essential
the
expert
and its conclusions
overload"
that
be as
an expert system
system,
must be combined
A human system
the user's a
attention
solution
sophisticated
spacecraft
board systems
ensure
Automating
safe and efficient
excellent
tools
system
designed
to the
to data
important
"information
an expert
to present
obfuscating
presenting The design Freedom
this
alone
cannot
and
user interface
the rationale below.
system
user
without
information.
is the key to clearly
status and expert
System
Human
expert
to the
of the user interface
Power
automation; solve all the
diagnostics. The
expert
for the design
to
systems
A both
system findings.
to the Space Station system,
specifics
Trouble,
and
will be discussed
problem.
This paper will discuss a user interface distribution
expert
The importance
to the power
of features
which simplify
assessing
status and which minimize
navigating
layers
of
discussed.
information and
SYSTEM
STATION
will
be
implementation
choices
will
through Design also
be
The Space
Station
for its day-to-day The
power
converting solar
presented.
for solar
flux
orbit.
"sunny" c
1993
SPACE
FREEDOM
Freedom
the
by the
Astronautics,
American Inc.
Institute All rights
of Aeronautics reserved.
"1
while
Station
energy
portion
is
into
is not available
To supply
requires
operation
the station
eclipse phase, excess
and
OF THE
system for Space Station Freedom.
system
Copyright
provide
information
2.0 POWER
rationale
Expert
to
required.
system's
the cause
this task is necessary operation.
the rest of the monitoring
well-designed
any by on
on the ground.
diagnosing
system
of monitoring
needs
aboard
as well as by specialists
can be tedious.
is the
is monitored
When the behavior is abnormal,
is always
to all the
system
Its behavior
expertise
it
Power System
power
to date.
problems
with process
to the
Freedom
with current
of the
interface
diagnoses
Station
however,
and respond
parts
most
are
For example, a user can confused if two or more
different
Space
the expert
Under these circumstances,
in
provides
a for
for a user to absorb
devices
key
this
monitoring
information. distracted and
unrelated
the
the application
If, in addition,
conclusions
of
is that it possesses
about
is
of the process.
available become
One
The
When the user consults
process
concise
events
1,0 INTRODUCTION
of an expert
large body which
A. Muller
Cleveland, Ohio 44135
Abstract
Expert systems
and Pamela
Aeronautics and Space Administration Lewis Research Center
power
of the orbit
electric
orbiting obtained
through
electricity,
throughout with power
power
the earth.
however, the
station's
during
the
must be stored during
the
(insolation).
Freedom's
power system consistsof generation,
storage,
subsystem
and distribution.
collects
solar power
phase of an orbit using convert
solar
generated
power
electric
consumer
power
during
consists
of
photovol_c electric
The
of power
scientific astronaut.
experiment
to
This
energy
storage
to
carries
to an electric
pinpoint
the problem
and more accurate
problem
4.0 THE POWER
area,
DISTRIBUTION
power
supply
distribution
The power
distribution
expert system,
developed
at
Lewis
used by an
Cleveland,
NASA
power
distribution Bus
Isolators
(RPC), and
to
the
subsystem (RBI),
and v_'ous RPCs.
is designed
consumer. components Remote
Power
buses and cables These
The include
to
power Remote
subsystem
and
an
expert
corporation Explorer
II workstation.
process
system
detection, their
Data acquisition
the
Symptom
detection
RPC's
-
which
current flowing maximum
complexity
power
its
Diagnosis
the circuit breaker trips
symptoms
can
loss
faults and operating with
or the
may cause
protection
hardware
alone cannot be expected
explanations
advice. a
is also
of
the
graphical
the power
objects
is a set of rules
is responsible
for taking
searching
the
the latest
subsystem
is present
and
symptom interface.
for obtaining
distribution
corresponding
an anomaly's communicates
a multifollowing
user
or not an anomaly
in
and
Trouble.
that determine
failure
in the system. the
generated
database
cause. The graphical with the user.'
to user
An expert system of encountered user
INTERFACE
5.1 Implementation
details
The user interface
is built
to
Such an expert system,
well-designed
5.0 USER
margin between
settings
this complex.
PrOvide
explain interface
down the line.
insufficient
A human
deal with a system
combined
breaker exceeds
and the breaker
itself may fail.
whether
If
Inference
of this system can lead to
Operatingwith
the line current
assistan_t
value,
from
to overloads.
the flow of power
The inherent
inadvertent
power
through a circuit
allowable
interrupting
problems'
cut off
Reasoning
data acquisition, and
is responsible
updating
and the
consists
processes: diagnosis,
protected
" the RBI's
set-covering
by
Trouble
that
values
breakers
above.
and LISP running on a Texas Instrument
interconnections form the power distribution network. The distribution network and its hardware is by circuit
rule-based,
shell
in
faults in the
described
system
was
Center
OH to monitor and diagnose
distribution
independent
Controllers
connectin_s
components
Trouble,
Research
expert system written in ART (Automated
SUBSYSTEM
subsystem
to faster
EXPER
from a
Tool), The
leading
is and
resolution.
Trouble is an object-oriented, DISTRIBUTION
status
SYSTEM
power
3.0 POWER
The user is able
what the current
the
to many
ranging shaver
quickly
subsystem.
the status
batteries.
power
consumers
"at a glance"
subsystem
nickel-hydrogen
subsystem
types
to see
in the storage subsystem
recharge.able
different
arrays
power.
the user's task of understanding
of the power distribution
The generation
supplies
eclipse.
The distribution
simplifies
subsystems:
during the insolation
solar into
and is also stored
for use
three
interface,
2
Application developed (GSFC).
Environment by NASA The
user
using
(TAE+)
Goddard interface
the Transportable software
Space runs
package
Flight on
Center a
SUN
SparcStation 2 employing Ada
language
used
Motif under Unix with the
for programming.
system resides on a completely a method machines
(RPC)
protocol
protocol
protocols
and Remote
were
were
the
computer,
so
cycles.
ThE+
prototypmg
and
and conservative selected
Aria
programming
is designed
from the schematic
power
distribution
subsystem.
Both
the
use of
for its
for the power distribution
system
the top with the Roll Rings,
but RPC was the final
was
The user interface
Call
Procedure
top contenders.
implemented,
choice due to its reliability CPU
different
for sending information between different was needed. A socket-to-socket
communication
5.2 Screen layout
The expert
quick
language
power
distribution
generation
and
depicted
buses,
the
power
The
include loads,
at
connecting
with
subsystems.
on the schematic
(RBIs and RPCs),
The diagram begins a rotary joint
subsystem
storage
expert
diagram of the
devices
circuit
breakers
and lines connecting
the devices.
capabilities. The The user interface
screens
drawing package. are exercised
refined
souw_e
screens.
(THE+
that
offers
languages.)
The source
the icons.
The
and to display
process.
to our
code
This
can be judged
in the development
generates
mode.
portions of the screens
effectiveness
are completed
's
are drafted they
rehearsal
the dynamic
screen's
early
screens
Once the screens
using TAE+'s
mode animates that each
are designed with ThE+
reflects a
bottom.
with
These
distribution
flow.
only animates
is to add code to acquire
data as well as to respond to the user's
e.g.
such
that
from the top at the
form
a power
perspective
conveys
as well as the direction
of
As a result, terms such as up-stream and
down-stream
are easier to understand.
if an up-stream immediate
oriented
components
tree. The top-down
power
several
been
the roll rings to the loads
power
the
inputs.
circuit
breaker
For example,
is open,
parent) then all breakers below
(descendants)
will not be energized.
top-down
power
hierarchy
capitalizes
on everyone's
was
(i.e.
the
the parent
This notion
chosen
intuitive
of
because
it
understanding
of
gravity.
The TAE + environment user input; however, system
had
protocol system.
to be
is used
data coming handled
system
from the expert
separately.
The
data from determines
RPC
Remote
side evaluate
action
to
take
procedures
the data based
on
e.g. update alpha-numeric
sent the
Another buttons.
portion These
information
the
expert
information
what
remote
especially
The data is sent as an input parameter
a remote procedure.
received,
to handle
to call based on the data that needs to be
transmitted. interface
is well-equipped
to receive
The expert
procedure
what
of the screen
has
to flow downhill,
to users the connectivity
designed
of
schematic
is shown
and
ThE+
the
choice
code generated
next step
After
satisfaction,
so
power
power
to
on the user and determine type
of
data
values or change
colors.
provide
displayed
upon
may
be
not
control creates
screen.
required
at
function.
as legends
Reducing
to match
that
the gold button controls
times,
information.
for the button's
monitoring
are color coded information
all
clutteron the
a more comfortable
screen
Some
mode. The buttons
the means for hiding or showing
The buttons the
the
in the normal operating
The button names serve
example,
3
of the screen is reserved for control buttons control the amount of
they
screen
environment. the colors
of
control.
For
the display
of the
names are
of the devices,
displayed
association
in
therefore,
gold.
between
the devices'
This
feature
the button
names
makes
the
and its data readily
apparent.
Another
portion
messages. is
to
of the screen
explain
annunciator
abnormalities
export system. in the
for each
anomaly
When an operator
annunciator,
emphasize
that
the selection.
line
also
the anomaly. up
the annunciator
diagram,
and
abnormality
the
the
together.
user
to
of
the device,
see
the
relationship
When a message
an acknowledge
new message present, a fact that might in an all text area of the screen.
and
icons,
large
for
the
reduced
description
elements
We preserved
were
clicking
Human-Computer
the
standards
to be applied
interfaces s. The
Program
the
"clickable"
elements
element
a mouse
is
button.
change
the
selected
by
The clickable
the obvious
choice
and the lists of text -- not so obvious.
buttons on the screen to avoid
messages
The
and
for The
are all the same size and shape
confusion.
clickable
the detailed
emphasizing
lists of text,
display
the clickability elements
window
the have
of these items. on the screen
are
not elickable.
5.4
Volume
of
information
a_..d color
and
size
relation.
The less cluttered
the
effective
on
is to convey
is also
that there
is a
be obscured
opposed
to
distribution
some
messages system
Flight
to all the SSFP-related
user-
adopted.
The
4
and
delivers
and busses.
color
screens,
by colors and sizes as numbers. power
the
The
(lines),
The user
circuit
are used to convey potential.
components
that
while a bright green color shows
are energized.
power
to the required
of the cables
Colors
flow and electrical
shows
the mere
One way to reduce clutter
information
loads through a hierarchy
green
certain
the user interface
the screen design.
breakers,
(SSFP)
were
Clickable
when
the
the graphical
into two groups,
are the buttons,
appears
Standard describes
requirements
To assist
of the interface,
on it with
were too distribution
and the
of components
Freedom Interface
our
the standards.
divided
interface
however, of
for the
the design of the icons and
from
and "non-clickable'.
energized The Space Station
load
complexity
the sizes
notion of power 5.3,.Graphical
and load
circuit breaker
among
button
This makes the user aware
breakers
as
lines.
line
These visual cues make it easy
and the icons.
annunciator,
activated.
it
depicted
The sizes specified
The rest of the graphical
on the schematic
explanation
link the message,
explanation
messages
arrow
detailed
of
This text is visible and
and the size of circuit
annunciator,
of the problem.
were
as thicker straight
specified.
clicking, of
or cables
icons were also
components
that
The highlighted
the purple the
area
The shapes
user
to
Selection
line is selected,
does not obscure the schematic'. on the annunciator,
by the
appears in its own portion
above the annunciator.
when
are one
a particular
a text
lines
lines and the buses
user in the navigation
on the schematic
a more detailed description
the screen
The
line is highlighted
opens
This detailed description
for
selects
describing
straight
schematic.
At the same time, a purple
that has detected
an anomaly contains
occur.
detected
appears next to the device
diagram
only
they
that appear on the annunciator
line descriptions
arrow
if
to text
and its purpose
is always present and cannot be hidden.
The messages
line
is dedicated
It is called the annunciator
icons
the
A dim are
not
those that
can clearly see the path that
the power takes to get to the scheduled load. Tripping a circuit breaker causes all the devices down-stream to lose power
causing
those
components
to change
frombrightto dim green.
An energized
and operating,
distribution
network.
up,
from bottom
When a load
current flows through file
salience
is used
current.
a thermometer.
to top,
Thus
margin which
increases.
the breaker's
on over-current.
the operating
using a bar
The graph fills
as the current
The top of the graph represents for tripping
values
compared
are provided
with the power
current
meters
the essential
normal
operating
viewed
from
and
representing
the
because
highlighted
monitoring
conditions.
breaker are small
icons
the
path
display
information The
of and
linking
screens,
high
salience
choices
with
failure
explanation effective
arrows,
from
an
features,
namely:
reduced
design
information
content
anomaly
icons,
detection expert
distribution.
presents
diagnostic
This
of current
convey
concepts
complex
and
and
system
user
provides
an
system
for
interface
without events.
color
diagnostic
monitoring
reasoning
the monitoring
can
design
compromising The display
in terms
can
that are clear to its
scanned
be REFERENCES
at a
the system's
status.
When
an anomaly
on the display,
1. D.B. J.L.
when greater
detail
is needed.
Managing
D.D.
Problem The "statns-at-a-glance" the focus
user interface of the user's
design
strives
attention.
Color
Interaction Press,
E.M.
Liberman,
"Reducing
Computing
2.
using color and size
Manner,
Dolce,
(1993).
the
Power
Systems,"
in Aerospace
Woods,
"The
P.A.
Mellor
Cognitive
in Proc.
Conference,
Cognitive
Representation,"
and
Workload: 9th
AIAA
1,
Engineering
of
Human-Computer
and Complex Systems,
London,
Academic
(1991).
is one way to make an object distinguishable the
energized components ones.
by
the faulty device.
status-at-a-glance
power
available
from
of these
message
Trouble
salience
detected
is depicted
6.0 CONCLUSION
taking a closer look at the numerical values. Thus numeric information does not clutter the screen but is
to control
An anomaly
for example,
the need to know the actual numbers
occurs, the user naturally concentrates
5.6 Salience
on components
under
screen
or quickly
Size
with
to the operator.
dominate
a distance
glance without
component
importance
components
provide
for currents,
The characters
behavior.
breaker,
the graph shows
can be determined
and voltages.
energized
anomalous
in a circuit
is with the size.
attention
drawing a larger box around
charaetfrs
they are of secondary The
to focus
The amalgamation
5.5 Size of alphanumeric
trip values,
exhibiting
object
setpoint
a quick glance.
Numeric
color. Another way of drawing the user's
to a graphical
Current is depicted
graph that resembles
background attention
has voltage but not necessarily is connected
component
rest.
components: clearly
Similarly,
grey which
Color
is used the
stand
to
bright
florescent
out from
the annunciator
is clearly
distinguishable
emphasize
the dim
window from
the
3.
Space
Station Freedom
green
Computer
Interface
green
September
1991
is bright the dark
5
Program
Standards,
SSP
Flight 30570,
Humandraft
REPORT
DOCUMENTATION
Public reportingburden for this c_on
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collectionof information,includingsuggestionsfor reducingthis burden, to washington Headquarters5ennces, u=rec_oratetor Intormat_onUperatmns ans Hepons, ]z]_) uenerson Da_,rls Highway, Suite 1204, Adington,VA 22202.-4302, end to the Office of Managementand Budget, PaperworkReduction Projec_{0704-0188), Washington, DC 20503. 1. AGENCY
USE ONLY
(Leave blank)
2. REPORT
DATE
3. REPORT
December 4. TITLE
AND
TYPE
1993
AND
DAYE$
Technical
SUBTITLE
COVERED
Memorandum
5. FUNDING
Design and Implementation of a Status at a Glance Power Distribution Expert System
NUMBERS
User Interface for a WU-476-14-10
6. AUTHOR(S) Eugene M. Liberman, David B. Manner, James L. Dolce, and Pamela A. Mellor
7. PERFORMING
ORGANIZATION
NAME(S)
6. PERFORMING OR_A'.kATIO.
AND ADDRESS(ES)
REPORT
National Aeronautics and Space Administration Lewis Research Center Cleveland,
Ohio
D.C.
11. SUPPLEMENTARY
12a.
AGENCY
Aeronautics
Washington,
E-8248
44135-3191
9. SPONSORING/MONITORING
National
NAME(S)
AND
10. SPONSORING/MONITORING AGENCY REPORT NUMBER
ADDRESS(ES)
and Space Administration NASA TM-106412 AA-93--4657
20546-0001
NOTES
Prepared October,
for the AIAA: Computing in Aerospace 9, sponsored by the American Institute of Aeronautics 19-21, 1993. Eugene M. Liberman and David B. Manner, Sverdrup Technologies, Inc., Lewis
Parkway,
Brook
Park,
Ohio
44142,
Research Center_ Responsible DISTRIBUTION/AVAILABILITY
Unclassified Subject
13. ABSTRACT
NUMBER
(work
funded
by NASA
persona James L. Dolce, STATEMENT
(216)
Contract
NAS3-25266);
and James
L. Dolce
and Astronautics, Research Center and Pamela
San Diego, California, Group, 2001 Aerospace
A. Mellor,
NASA
Lewis
433--8052. 12b.
DISTRIBUTION
CODE
- Unlimited
Category
(Maximum
31
200 words)
Expert systems are widely
used in health monitoring
and fault detection
expert system is that it possesses a large body of knowledge about the user consults this knowledge base, it is essential that the expert as concise as possible. If, in addition, an expert system is part of a conclusions must be combined with current events of the process.
applications.
One of the key features
the application for which it system's reasoning process process monitoring system, Under these circumstances,
of an
was designed. When and its conclusions be the expert system's it is difficult for a user
to absorb and respond to all the available information. For example, a user can become distracted and confused if two or more unrelated devices in different parts of the system require attention. A human interface designed to integrate expert system diagnoses with process data and to focus the user's attention to the important matters provides a solution to the "information overload" problem. This paper will discuss a user interface to the power distribution expert system for Space Station Freedom. The importance of features which simplify assessing system status and which minimize navigating through layers of information will be discussed. Design rationale and implementation choices
14.
SUBJECT
will also be presented.
TERMS
GUI, Human factors; Human Man machine interface 17.
SECURITY CLASSIFICATION OF REPORT
Unclassified NSN
7540-01-280-5500
15.
NUMBE_
16.
PRICE
OF PAGES
6 interface;
Expert system;
Space power
systems;
CODE
A02 18.
SECURITY CLASSIRCATION OF THIS PAGE
Unclassified
19. SECURITY CLASSIFICATION OF ABSTRACT
20.
LIMITATION
OF AB$-i-_ACT
Unclassified Standard
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2-89)
Prescribed by ANSI Std. Z39-18 298-102
