[From Bruce Buchanan 9940906.23:50 EDT)]
Rick Marken (940906.0900) writes:
...the only "problem" faced by a hierarchical control system is getting it's
perceptual signals to match its reference signals. There is no really other
problem - - real or imagined. . . .
. . .If a control system is successful at controlling a perceptual
variable, it has implicitly solved the "real world" problem of dealing with
the (often variable) physical constraints linking action to perceptual
input. . . .
(and also . . .)
. . . But it is true that the
nature of the lower level perceptual signals that can be varied by the
higher level systems as the means of achieving it's goals can present a
problem to the higher level systems if the appropriate lower level perceptual
variables are not available.
I appreciate the clarification. I guess that my own hierarchical control
system (at its level of systems concepts) is set to the view that any
control systems we can discuss are essentially made up of abstract
representations within the brain/mind of organisms that exist as part of
their environment. So the relationship of the control systems to the
context of living continues to interest me, although I realize that we can
only know the world in terms of our perceptions.
Cheers!
Bruce B.