Report of the Second Piloted Aircraft Flight Control System - Acgsc.org

The constant k helped to improve the fit at low frequenciee. Using tuo
cam apeeda Tuatin studied eight frequencies from .018 to204 cp.
L. ~uesell~ in a recent MIT meatarts thesis conducted an eate~ive
series of experiments in a stdy of linear approximatione to human tracking
behavior. He used a beet linear model plue noise approach and
employed a signal of four harmonica whioh odd be presented at three
speeds. He thus had a range of from .Q442 to 1.43 cp in the input
signal. Russell evolved an eqmtion similar to the Phillip equation.
Russell indicated that the husrpn appears to adjust hia response parameters
in order to minimiru, the meen square error in tracking a signal of given
power epectrwn. In addition the humen appeera to set hla gain at a value
yielding a reasonable margin of stability. It is well to point out that
the parameters found for the four preceding operationel ~preseiona were
all different. The fact that a, b, and c differed indicates thet the
human's response ia peculiar to given apparatus and display problem.
The variation in L from .3 eeconda to .5 seconds is probebly a function
of the training of the operators and the predictability of the signal.
North? in a reoent paper on the humen transfer Function, he8 developed
a sophisticated framework for the study of human transfer functions.
A mean linear operator of simple form is postulated and in addition the
cbracteristice of a superimpdeed stochastic distribution are discussed.
In simple position treickfng North postulates a relation of the form
as the mean steady state operator; and, in addition, he posits a treneient
which is kept in a state of continuoue excitation by the stochastic
elements. This problem is studied by a epstem of finite difference
equations as well as by differential equations in vim of the evidence
for discontinuity of human operator tracking responses. The discontinuity
arises from the fact that there ia a refractory per,iod in tracking since
the human appears to prseet reaponsee in accordance with his beet esthate
fro@ available data, and that these responses, once initiated, can not be
cksnged continuously. The stochastic process arises from two sources8
one, is inaccurate eathatid of the input signal, and two, is the inability
of the operator to perform the appropriate response.