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

The data suggest the need for rethinking the task of continuous
control of hlgher-order systems. In all cases the major period of aileron
control activity was on the order of 8-12 seconds. Data for elevator
control (Figure 5) indicate a major period on the order of 3-10 seconds
depending on the display dynamics used. It may be that these major
control decisions are made discretely at the cognitive level, whereas the
trial and error searching for more information as seen in the lower-order
predictor displays and in the conventional crosspolnter display is made in
a continuous fashion. Clearly, predictive display dynamics have a
considerable effect on the amount and types of cognitive processing (and
control movements required for perceptual processing) required in the
control of an aircraft on a curved approach.
..... Figure 5 here ......
Figure 5. Power spectral analysis of elevator control responses.
Flight Task Analysis
In an analysis of the pilot's control task, a significant component
that can be identified is cognitive prediction resulting from the mental
transformations required by the aircraft control hierarchy. For example,
to correct an error (due to dishurbance inputs, pilot control errors, or
course curve adjustments) in the horizontal direction, the pilot estimates
the amount of heading change that is necessary to effect an optimum
correction. Given this estimate of the necessary heading adjustment, the
pilot estimates the optimum bank for that heading change. Finally, given
an estimate of the necessary bank and pitch, the pilot estimates the
amount of aileron control movement appropriate for that amount of bank
change. Considering the vertical component that must be controlled
simultaneously, the cognitive prediction task is very demanding. This
task is the major element to be learned initially in instrument approach
instruction and it is often the first to be forgotten in the loss of
instrument "currency." If the amount of control power is proportional to
the amount of cognitive processing involved, then the most effective
display would be that which causes pilots to produce the least amount of
control power and error in both the lateral and vertical modes.
The Perceptlon-Actlon Cycle
The research work by Owen and his associates (Owen, Warren, Jensen,
Mangold, and Hettlnger, 1979) suggests that perception is a active
process. They have advanced the idea that a considerable amount of the
control activity input by the operator of a vehicle is made for the
purpose of obtaining information rather than correcting error. This may
explain the phenomena that we see in the lower-order display where a high
level of control activity is evidenced. These results suggest that a
detailed analysis of control style is essential for an understanding of
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