[Martin Taylor 930622 11:30]
(Hans Blom, 930621)
It seems to me that just as a power gain is an essential element of
the outflow side of a control system, so a corresponding power loss
is an essential element of the inflow (perceptual) side. The
perceiving of the state of a CEV should not contribute as a disturb-
ance any more than it must (Heisenberg showed that it must, to some
extent).How true. Very familiar, too. In my blood pressure controller, the
arterial pressure must be measured. Imagine what a thick needle in a
thin blood vessel can do to disturb the circulatory system and thence
the pressure measured!On the other hand, the output power of the control
system wants to have maximum effect on the CEV, or as tight coupling
and as high power gain as is feasible, given the information limita-
tions on the perceptual side.Feel that micromanipulator carefully tear a single cell away from its
surrounding tissue as your hand squeezes on the macroscopic counter-
part of the micro-pincer. Power GAIN? No! Very carefully scale the
power down! Almost Virtual Reality...
You are mixing up different control systems, I think. The perceptual
energy levels must be greatly reduced from levels that would tear
away that single cell; the corresponding output must come back up to
a level that permits the cell to be torn away. You have to look at
both in the same environment. The output must have enough energy to
dominate any random effects on the CEV, and enough to counter whatever
disturbance there might be (which normally would be substantially greater
than the random effects). The perceptual input, on the other hand, must
be based on sensors that work below the level of the random effects on
the CEV, or at worst at the same energy level. There has to be a
substantial power gain on the output side that (to an order of magnitude)
compensates for the power loss between CEV and sensor.
The fact that in your example there are several intervening control
systems that work at very different power levels is irrelevant. There
may be great power gains and losses on both sides of the multi-level
circuit, but in the end, they must more or less compensate when measured
between the CEV and the perceptual signal that corresponds to the CEV.
Martin