expensive
ment.
"shell."
gram with
stem, the
inference
built in.
wledge is
engineer.
more cost
ince the
read over
widespread
has been
Is. Until
| powerful
| the past
as expert
| computer
le. This
ore viable
the cost
[ON
alls under
ce. Most
nventional
y they can
le. AI or
oduce some
neering.
ions where
ties is in
g, optics,
plications
nd design.
and optics
ert system
scribe the
it is used
blems for
OR
sor expert
ighting and
of machine
1all parts
of machine
jf possible
rification,
gauging,
initially,
ited to one
system has
h little or
n use it.
n knowledge
pert system
cess became
see how his
o facts and
re are over
three hundred rules in the Lighting Advisor
expert system data base at the time this paper
is being written.
PENN VIDEO LIGHTING ADVISOR
What is the purpose of this consultation?
Yes:
* LIGHTING
* LENS CALCULATION
* COLOR ANALYZING
1. Use arrow keys or first letter of item to position cursor.
2. Select all applicable responses.
3. After making selections, press RETURN/ENTER to
continue.
PENN VIDEO LIGHTING ADVISOR
What is the feature of interest?
HOLE OR CAVITY
RAISED SURFACE (SUCH AS A BRACKET)
FEATURE SILHOUETTE
FEATURE PRESENCE OR ABSENCE
SURFACE FLAWS (CRACKS OR CAVITIES)
FEATURE OR SURROUNDING AREA FLUORESCES
UNDER ULTRAVIOLET LIGHT
1. Use the arrow keys or first letter of item to position the
Cursor.
2. Press RETURN/ENTER to continue.
Figure 2
Two examples of questions asked
in Lighting Advisor
The Lighting Advisor uses a personal computer
as its work station. The software is menu
driven with help available at all times. The
user tells Lighting Advisor about his/her
application by answering a series of questions
and making choices from the menus. See figure
2. The questions pertain to the nature of the
PENN VIDEO LIGHTING ADVISOR
How close can you put the light source to the feature of
interest? (in inches)
Help ooo
One of the factors in suggesting appro-
priate lighting is the minimum distance
that a light source can be placed to the
feature. Consider any physical restric-
tions in the process or environment. If
you are not sure of the physical limita-
tions, rerun the Expert System choos-
ing a different light distance each time.
**End- RETURN/ENTER to continue
1. Enter a positive number.
2. Press RETURN/ENTER to continue.
Figure 3
Help in understanding questions
about an application
application, the feature and background surface
qualities, whether the object is moving or
stationary during the inspection, etc.
On-line help is available for each question at
any menu level. One of the help screens is
shown in figure 3.
Structured
Camera Lighting
(Shadow Casting)
Light / S 7
g J
- Shadow
ut.
Part
Press ENTER to continue
Figure 4
A graphic representation of
a suggested lighting technique
The expert system reviews the answers given and
returns a set of conclusions that include:
1. The lighting technique. For example:
Front-light field.
2. The light source. For example: Quartz
halogen lamp with reflector.
3. The camera lens. For example: The
calculated focal length is 89.6. Use a 75
mm fixed focal length lens. Use a zoom
lens with a focal length of 89.6 included
as its usable range.
4. Possible color or polarized filtration or
special optics requirements. For example:
Use a beam splitter.
To help explain the Lighting Advisor
conclusions, the system shows several color
illustrations using the PC's graphics
capabilities. Figure 4 shows the camera and
light position when structured lighting is used
to cast shadows.
A Case Study
This application was done two years prior to
the development of the Lighting Advisor expert
system. It was among many of the applications
used to help prove and debug the expert system.
The application requires a machine vision
inspection of a critical dimension on an
aluminum transmission case. The measurement
needed is between an area on the side of the
case and a mounting hole perpendicular to that
plane. The arrows in figure 5 show the two
points that the measurement is between. The
accuracy of this distance insures that there is
adequate clearance for the starter assembly to
be attached.