Tricks, Bruce and Gary and Autonomy

[From Rick Marken (950516.2045)]

Martin Taylor (950516 11:00) --

The models you are throwing back and forth do not seem to be
realistic models of continuous systems. Much of their behaviour is
likely to be due to computational artefacts, which obscures the main
message of Hans's "difficult disturbances" and of Bill's model's
(in?)ability to compensate for them.

Since the model to which you refer accounts for 99.9% of the variance
in the behavior of living control systems, I'd say those "computational
artefacts" are considerably less important than you seem to think? The
integral control model is a realistic digital implementation of a control
system operating in a continous environment.

Bill's model is not representative of any real control system, because
real systems do not have infinite power available

To say that the model is not represetnative of any real control system is
misleading. The model is precisely representative of real living control
system when the proper parameters are selected. It is the organization
of the model that is "representative", not the specific parameters.

But Bill finds that unless he plays a trick, even his computer model
lacks power and will fail to control

There was no trick. Hans was trying to say that the simple, integral
control model could not control under certain common disturbance
conditions and that, therefore, a "model based" control system is
necessary . Hans' own data show that he is wrong; the perceptual control
model maintains control even under the most adverse disturbance

This "liberty" taken with the model makes Hans's point, that
assumptions about the disturbances are implicit in the structure of the
control system.

This is wrong. The "liberty" of which you speak was dividing the
disturbance by 160 to prevent overflow; the division could have been
avoided (and the control system would have continued to work) if Bill
had cast the distrubance and output variables to floating point. This
division had nothing to do with "assumptions about disturbances...implicit
in the structure of the control system". There are no such assumptions
in a control system; this claim of yours is (more) nonsense.

The ability of a control system to control depends on how much output
it can generate per unit error (gain), the upper limit of this output
(strength) and speed (integral and transport lag).Is this what you're
trying to reveal unto us?

Bruce Abbott (950516.1110 CDT) --

Guess where I am? Why, visiting the net god, that's where!

Worship him for me.

I'm here showing Gary Cziko how everything is S-R after all. I
wouldn't have believed it myself, but Gary showed me Rick's
"Autonomy" stack, and that did it.

I thought there might be a problem with that one. I'll have to let Bill
fix it up with one of those "tricks" of his;-)

Have a great time you guys.