No problem with you posting here, Carmen, and welcome to the IAPCT Discourse forum. I’ll be glad to talk further outside the forum if you wish, but I hope you will have more to say here in the future. You can email
- Bruce Nevin <bnhpct@gmail.com>
I try to keep PCT-related email there. We can also use zoom or phone if appropriate.
Simulation and test goes beyond my computational chops (and evidently beyond my willingness to devote time to building programming skills) so your engagement is very important and exciting.
‘Standard control theory’ often incorporates some complications that have not been necessary for modeling behavior of living things, and in some cases are not plausible. In many cases, the set point is determined from outside the system, and this is in general not accessible in living things. The ‘controller’ is sometimes conceived as containing a model of relevant aspects of the environment, or that plus a model of an observer. A crucial principle of PCT is adopting the point of view of the control system and its purposes. Control engineering typically has the point of view of an observer or analyst in which the control system is understood as serving purposes that are posited from that external point of view. Unwitting equivocation across points of view (organism, observer, experimenter, analyst, designer) has sometimes confused discussion.
A 1999 post by Mary Powers is pertinent. Mary reiterated the obvious fact that stability is a prerequisite for survival, and the control systems that have evolved as and within living organisms, sans pathology, patently are stable. It is possible that means of stability in engineered systems mimic what has evolved, and in any case the deep preoccupation of control engineering with stability is necessary for a similiation.
I’m in the middle of a deep dive into the neurophysiology of the cerebellar system. Bill published a first essay at modeling this evolved system in Chapter 9 of Behavior: The control of perception (familiarly called B:CP). Knowledge of the neuroanatomy and of details of functioning has advanced greatly since the publications of (Nobel Prize winner) Eccles and his colleague Ito in the late 1960s, but understanding lags, in part due to myopic attention to one or another part of this distributed system, in part clouded by presuppositions. A deep dive certainly does mean over my head. I hope to resolve this to a tight presentation (in 30 minutes) that more capable minds can pursue aright.