Early AI Diagnostics at Westinghouse
turbine diagnostic system, GTAID, is used to
follow over 1200 gas turbines.
Including the system shell programmers in
the team meant that a request for a new
feature could be accommodated in a few
days. Because roadblocks due to limitations
of PDS could be removed quickly, the
knowledge engineers could continue
working, almost without interruption.
The development group, at its peak about
1989, included two programmers who
maintained the expert system shell, two
chemists working on ChemAID, four
mechanical engineers working as knowledge
engineers on GenAID, four engineers
working on TurbinAID and a physicist who
acted as an instrument inventor so that
when a measurement was needed, there
was a way to get it. In addition, specialists
from the entire engineering staff of
Westinghouse made contributions to
individual rules.
A third important lesson for the construction
of such systems was the step by step
approach.
This approach promotes
transparency, and transparency is useful in
explaining a diagnosis. It is also valuable
when a section of the rulebase must be
modified. Modification of complex rules
invites
unintended
consequences.
Modification of simple, one-step rules is
much less likely to have unintended
consequences.
L ESSONS L EARNED
One important lesson to be found in this
narrative is that the audience for the expert
system is important to its potential
commercial success. GenAID ® was written
for the operator, who might know that
something was wrong, but was usually not
able to diagnose the problem. ChemAID ®
was written for the chemist, who could
generally diagnose the chemistry problems.
ChemAID ® did not survive the lean years of
the 1990s.
The author would like to acknowledge
helpful conversations with Eric Harper, one
of the PDS programmers, who first
suggested writing this paper. The author
would also like to thank all the people who
contributed to the development of the
Westinghouse AI Diagnostics systems for a
very rewarding and stimulating decade
during the 1980s.
A second important lesson was the
integration of the development team.
IIC Journal of Innovation
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