[From Rick Marken (950516.0800)]
Hans Blom (950516)--
I will demonstrate some worlds in which this [simple PCT] controller cannot
control at all or looses control temporarily.
Actually, as Bill Powers (950516.0530 MDT) just showed, this little PCT
controller hardly loses control at all, even with your rather extreme
disturbances (some of which are equivalent to the Oklahoma blast -- and not
many real control systems were able to main control after that). As Bill
Powers notes:
In the "clincher" example (4) it [the simple PCT controller] was able to
keep the error to 0.0039 of what it would have been without the opposing
output.
So Hans' demonstration of "control going down the drain" is (as usual)
pretty unimpressive, especially considering the fact that Hans' own very
complicated "model- based" controller (which, I presume, was supposed to
teach us a "lesson" about control) was unable to maintain control in the face
of ANY disturbance at all.
By the way, Hans, I have developed a simple PCT type control model that meets
and exceeds your specifications for a controller that has "approximately zero
response time" while it "tracks a repeating waveform". The response time of
this controller, measured as the average delay between target waveform and
cursor movement, can be 0 or even positive (the cursor leads the target)
depending on parameter adjustment. The model controls a perception of the
difference between cursor position and the sum of target's position and
derivative.
Hans, you've been hanging around csg-l for several years now? I am still
wondering what in the world you are trying to teach us. Do you agree that
all control systems -- living and non-living -- are typically organized
arouind the control of their own perceptions? Are you just trying to expand
the application of the control model to cases where the control system is
deprived of perceptual input? What is your point?
Best
Rick