18th annual conference on manual control.pdf - Acgsc.org

absolute levels of control performance between experiment and model disagree
slightly, relative performance levels agree well. This is demonstrated by comparing
model predictions (at a fixed fc_6) for cases 1-3 with the experimental
results. The eRMs experimental results for cases 1-3 are consistently higher
than the model predictions. An explanation for this fact is that the OCM assumes
a well-trained subject, whereas the actual subjects -- not being pilots -- were
not fully trained with respect to the AI0 dynamics. While it is possible to
model this effect a posteriori in the OCM by increasing observation!motor noise
and/or TN, this was not an objective of our efforts. On the other hand, the
absolute performance levels for model and data in case 4 are in close agreement.
The reason for this is that the "system" dynamics as perceived by the subject
are similar to K/s. These dynamics are trivial to learn, so that training
effects (after but a few trials) are inconsequential.
CONCLUSIONS
An analytic, pilot model-based, display design methodology has been applied to
study workload and performance trade-offs in a high-speed, terrain-following
task. The methodology combines pilot limitations, aircraft dynamics and performance
requirements in order to determine the requisite information that
must be supplied to the pilot.
Man-in-the-loop experiments that evaluated the performance of the four candidate
display systems were conducted at the University of Connecticut. The
objective of these experiments was to validate the overall display design procedure,
including the flight director design synthesis process. Two positive
conclusions resulted from this effort.
VALIDATION OF DISPLAY SYSTEM PERFORMANCE
The fixed-base experiments invoived a terrain-following control task. (A secondary
monitoring task was also included but is discussed elsewhere [6].)
The experimental relative rank-ordering of the four display systems, based on
control performance, was identical to that predicted analytically at the display
element level. It suggests that a large number of potential display (or
control augmentation) systems can be evaluated analytically at low expense,
and then the most promising options can serve as the candidates for subsequent
manned simulation. The time and cost savlngs of a model-based "front-end" to
the complete design process can be substantial.
The spread in absolute levels of performance between the first three display
systems and the flight director display was found to be much greater in the
experiments than in the mode! predictions. Our explanation of this result is
that the model assumes a well-trained pilot, whereas the subjects were not
well-trained on AI0 dynamics and so their performance was not at the modelpredicted
levels. On the other hand, the flight director essentially normalizes
out the aircraft dynamics, rendering the control task much simpler and
requiring virtually no learning. Here model and data absolute performance
levels were commensurate.
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