[From Rick Marken (960118.0800)]
CHUCK TUCKER (960117A) --
What might be confusing is that Rick states that the "perceptual variable,
p." is "controlled" while Bill states that "The prime mover is the reference
signal, not the behavior." so it may appear that there is a conflict between
Rick and Bill when they describe the "loop."
Ok. This is a good point.
I was talking about the fact that the perceptual variable is the only
variable in a control loop that is kept under control (kept in a reference
state and protected from disturbance). Bill was talking about what makes this
control (of perception) happen; what the "prime mover" or ultimate "cause" of
the fact that a variable is kept in a particular, controlled state is.
The prime mover is not any variable in the loop because every variable in the
loop is both "mover" and "moved" at the same time. So the prime mover is not
"behavior", where this term could refer to changes in any variable in the
loop -- perception, error, action, input -- or to the loop as a whole. The
prime mover - - the variable that determines that the perceptual variable is
controlled at a particular value -- is the reference signal.
I think what Bill said complemented what I said. I talked about "what" is
controlled (perception); Bill talked about "why" perception is controlled
(reference signal). The discussion with Bruce Abbott about closed loops has
to do with "how" perception is controlled (simultaneous effect of input on
output and output on input).
Hans Blom (960116) --
Remember that my controller was able to remain in control when no
observations were forthcoming
I remember that your controller maintained its output while input
(observations) were cut off. I also remember that the controlled variable
remained in the reference state as long as no disturbances were added during
the non-observation period (or the observation period, for that matter). But
I don't remember it remaining in _control_ (keeping a variable in a reference
state and protecting it from disturbances) when no observations (perceptions)
were forthcoming. But Bill might remember differently.
Best
Rick