LCS III Course: Chapter 1 Concepts of Control

[From Rick Marken (2014.01.27.1240)]

Well I’m glad to see my summary of the Foreward didn’t meet with any objections (so far) so let’s proceed with Chapter 1. Right up front Bill says this chapter is “not strictly necessary for what comes next” but we’ll treat it as necessary and spend the next two weeks discussing it. So here are some discussion questions:

  1. Bill starts by saying that “Whatever method of control one proposes the basic concept of control is the same.” He then defines control. Based on what we discussed regarding the Foreward (The Fact of Control) what do you think Bill is getting at in this paragraph.

2, In this chapter Bill discusses two approaches to explaining control – two versions of control theory: Modern Control Theory (MCT) and Classical Control Theory (which is what PCT is). Bill says that MCT has been a “formidable obstacle to the acceptance of PCT”. Based on your reading of the section on MCT why do you think this might have been the case? That is, why might the MCT approach to explaining control have been an obstacle to acceptance of PCT?

  1. On p. 9, paragraph 2 Bill says that “A negative feedback controller…doesn’t have to know what is causing the speed [controlled variable] to change.” The rest of the paragraph goes on to explain why this is so and why this distinguishes the PCT (classical) controller from the MCT controller. In your own words can you describe how this description of the PCT model of control differs from the MCT model.

  2. Why do you think Bill included the section on Simulation and Modeling in this chapter?

  3. What would you say is Bill’s point in the last section of the chapter on Philosophy of Science? Why do you think he would include it?

  4. Finally, consider the last sentence of the chapter: “Control, like digestion, is something everyone does but hardly anyone understands.” Is Bill talking about these things – control and digestion – as theories or facts?

Of course, feel free to comment on anything else you find to be of interest in Chapter 1 (or in the Foreward). Hopefully by the time we finish this chapter everyone will have a copy of the book and we can proceed to the meat of the book, starting with Chapter 2, with everyone on board.

Best regards

Rick

···


Richard S. Marken PhD
www.mindreadings.com
The only thing that will redeem mankind is cooperation.
– Bertrand Russell

[From Fred Nickols (2014.02.02.1520 EST)]

My responses to Rick’s questions are embedded below.

···

From: Richard Marken [mailto:rsmarken@GMAIL.COM]
Sent: Monday, January 27, 2014 3:41 PM
To: CSGNET@LISTSERV.ILLINOIS.EDU
Subject: LCS III Course: Chapter 1 Concepts of Control

[From Rick Marken (2014.01.27.1240)]

Well I’m glad to see my summary of the Foreward didn’t meet with any objections (so far) so let’s proceed with Chapter 1. Right up front Bill says this chapter is “not strictly necessary for what comes next” but we’ll treat it as necessary and spend the next two weeks discussing it. So here are some discussion questions:

Bill starts by saying that “Whatever method of control one proposes the basic concept of control is the same.” He then defines control. Based on what we discussed regarding the Foreward (The Fact of Control) what do you think Bill is getting at in this paragraph.

[Fred Nickols] I think he’s simply laying out the basic nature of control in a negative feedback sense.

In this chapter Bill discusses two approaches to explaining control – two versions of control theory: Modern Control Theory (MCT) and Classical Control Theory (which is what PCT is). Bill says that MCT has been a “formidable obstacle to the acceptance of PCT”. Based on your reading of the section on MCT why do you think this might have been the case? That is, why might the MCT approach to explaining control have been an obstacle to acceptance of PCT?

[Fred Nickols] For me, it all boils down to the age-old pursuit of either being able to control people or to replace them with machines. PCT says the first is difficult if not impossible and machines that could behave in accordance with PCT would present the powers that be with the same problems presented by people; namely, the need for autonomy.

On p. 9, paragraph 2 Bill says that “A negative feedback controller…doesn’t have to know what is causing the speed [controlled variable] to change.” The rest of the paragraph goes on to explain why this is so and why this distinguishes the PCT (classical) controller from the MCT controller. In your own words can you describe how this description of the PCT model of control differs from the MCT model.

[Fred Nickols] It is the difference between controlling some variable and calculating output.

  1. \Why do you think Bill included the section on Simulation and Modeling in this chapter?

[Fred Nickols] To set the stage for what follows and to lay the foundation for the importance of modeling.

  1. What would you say is Bill’s point in the last section of the chapter on Philosophy of Science? Why do you think he would include it?

[Fred Nickols] To illustrate the flaws in so-called “scientific thinking.”

  1. Finally, consider the last sentence of the chapter: “Control, like digestion, is something everyone does but hardly anyone understands.” Is Bill talking about these things – control and digestion – as theories or facts?

[Fred Nickols] Facts, but poorly understood ones.

[From Adam Matic 2014.02.03.0033 CET]

Rick Marken (2014.01.27.1240)
2, In this chapter Bill discusses two approaches to explaining control -- two versions of control theory: Modern Control Theory (MCT) and Classical Control Theory (which is what PCT is). Bill says that MCT has been a "formidable obstacle to the acceptance of PCT". Based on your reading of the section on MCT why do you think this might have been the case? That is, why might the MCT approach to explaining control have been an obstacle to acceptance of PCT?

AM: Perhaps it's because PCT seems very simple compared to MCT, and it's 'common knowledge' that behavior is very complex, so it couldn't be explained by simple negative feedback loops. Although, from my experience, once you get to multilevel structures, things quickly stop being simple.
Another obstacle is, of course, the fact that MCT (with some exceptions) refers to the output variable as the controlled variable. It's a different perspective that often results in very different designs of control systems. While PCT is more 'from the view of the control system' perspective, MCT takes an external, engineer-designer perspective.

3. On p. 9, paragraph 2 Bill says that "A negative feedback controller...doesn't have to know what is causing the speed [controlled variable] to change." The rest of the paragraph goes on to explain why this is so and why this distinguishes the PCT (classical) controller from the MCT controller. In your own words can you describe how this description of the PCT model of control differs from the MCT model.

AM:
The main difference is that in PCT there is no attempt to pre-calculate the future state of the controlled variable, either input or output, from some other perceived variables.
Related to the feedforward discussion, from what I understand, not all feedforward is prediction using formulas and complex mathematics. Some types of hybrid feedforward and feedback systems are constructed so that feedforward improves control,but this is only possible when the 'plant' is known. It might be that human memory works similar to these feedforward components. When we develop a skill, it might be that we use something 'more' than pure negative feedback (not something more then PCT, though).
I've been reading some flyball catching experiments, this one seems relevant:
The effects of baseball experience on movement initiation in catching fly balls (Oudejans, et all 1997) <http://dare2.ubvu.vu.nl/bitstream/handle/1871/28892/113994.pdf&gt;http://dare2.ubvu.vu.nl/bitstream/handle/1871/28892/113994.pdf
Abstract:
Previous research has shown that skilled athletes are able to respond faster than novices to skill-specific information. The aim of this study was to ascertain whether expert outfielders are faster than non-experts in acting on information about the flight of a fly ball. It was hypothesized that expert outfielders are better attuned to this information; as a result, faster and more accurate responses were expected. This hypothesis was tested by having non-expert and expert outfielders judge, as quickly as possible, where a ball would land in the front- behind dimension (perceptual condition) and, in another condition, to attempt to catch such balls (catching
condition). *** The results of the perceptual condition do not support the hypothesis that expert outfielders are more sensitive to ball flight information than non-experts, *** but the results of the catching condition reveal that experts are more likely to initiate locomotion in the correct direction.

What we can see is that skilled catchers are no better than unskilled ones in *predicting* where the ball will fall from initial flight information. That would be expected if humans were analyse-compute-act systems. Improving a skill would mean improving the ability to predict the end point from initial conditions.
On the other hand, there are some differences between skilled catchers and unskilled ones, for example - that the skilled ones start moving later then unskilled ones after the ball starts flying. So, something does change in their internal control systems, and perhaps it is only the gains of the visual 'ball catching' control systems, and perhaps it something else that we can try to explain.

4. Why do you think Bill included the section on Simulation and Modeling in this chapter?

AM:
Why it is in this chapter? I don't know. I could be a separate chapter from what I can tell. Modelling is a very important concept in PCT and other sciences.

5. What would you say is Bill's point in the last section of the chapter on Philosophy of Science? Why do you think he would include it?

AM:
The point is that what is missing from the study of life in sciences is the notion of control. He might have included this section to illustrate how fundamental the concept of control is to studying life, right down to the foundations of life acting according to physical laws.

6. Finally, consider the last sentence of the chapter: "Control, like digestion, is something everyone does but hardly anyone understands." Is Bill talking about these things -- control and digestion -- as theories or facts?

AM:
As facts. Humans digest and humans control. What is also important is that biological control is is hard to understand and we are just beginning to explore it.
Adam

[From Rick Marken (2014.02.06.1145]

Here's my quick take on the questions I submitted re: Chapter 1 of LCS
III. The replies I got were quite good. I really don't have much to
add. So this should be short, I hope!

1. Bill starts by saying that "Whatever method of control one proposes the
basic concept of control is the same." He then defines control. Based on
what we discussed regarding the Foreward (The Fact of Control) what do you
think Bill is getting at in this paragraph.

My take on this is that there are many designs that will achieve
control but that the basic fact of control is the same: maintaining a
variable in a predetermined (reference or goal) state protected from
undetectable and _unpredictable_ disturbances. I think he puts it this
way because he will describe in this chapter Modern Control Theory
(MCT), a means of control that works (because it operates in a
negative feedback loop) but can lead to a misunderstanding of how
control works when it's described.

2, In this chapter Bill discusses two approaches to explaining control --
two versions of control theory: Modern Control Theory (MCT) and Classical
Control Theory (which is what PCT is). Bill says that MCT has been a
"formidable obstacle to the acceptance of PCT". Based on your reading of
the section on MCT why do you think this might have been the case? That is,
why might the MCT approach to explaining control have been an obstacle to
acceptance of PCT?

I think MCT became an obstacle to acceptance of PCT because MCT
involves prediction of output based on input, which makes it seem like
control requires prediction of output in order to work. MCT also makes
it seem (to psychologists) like goal oriented behavior is based on
generating anticipatory outputs that achieve the goal. This conflicts
with the PCT message that goal oriented (purposeful) behavior is
organized around the control of input, not output. So the popularity
(and acceptance) of MCT is an obstacle to acceptance of PCT.

3. On p. 9, paragraph 2 Bill says that "A negative feedback
controller...doesn't have to know what is causing the speed [controlled
variable] to change." The rest of the paragraph goes on to explain why this
is so and why this distinguishes the PCT (classical) controller from the MCT
controller. In your own words can you describe how this description of the
PCT model of control differs from the MCT model.

In order to predict the output that will protect a controlled variable
from disturbances one has to know (perceive) what those disturbances
are. The negative feedback control loop doesn't need to know what is
disturbing a controlled variable; all it needs to know is the
perceived state of the controlled variable relative to the reference;

4. Why do you think Bill included the section on Simulation and Modeling in
this chapter?

I think it's because understanding control theory really requires an
understanding of how the model works. And evaluating control theory is
all base on comparing data to models. Although one can probably get
the gist of PCT without knowing how to build computer models, the
modeling really helps one get thgeir head around what's going on.

5. What would you say is Bill's point in the last section of the chapter on
Philosophy of Science? Why do you think he would include it?

I think this section was about dealing with arguments against (or for)
PCT based on basic physical principles; that since organisms are built
of matter their behavior must obey the causal laws that govern the
behavior of matter. But Bill points ot that it's the _organization_ of
matter that determines the kind of behavior generated by things made
of matter. Specifically I think Bill is saying that justifying the use
of a causal model of behavior in psychology because "that's science"
doesn't cut it. When matter is organized as a closed negative feedback
loop (rather than as a lineal causal -- open loop--process), the laws
that determine the behavior of that system are the laws of control
rather than causality.

6. Finally, consider the last sentence of the chapter: "Control, like
digestion, is something everyone does but hardly anyone understands." Is
Bill talking about these things -- control and digestion -- as theories or
facts?

Yes, again Bill is emphasizing what he uses as the subtitle of his
book: control is a fact, an observable fact and control theory is what
we use to understand that fact.

Now on to Chapter 2, for which I see David has already posted some questions.

Best

Rick

···

Of course, feel free to comment on anything else you find to be of interest
in Chapter 1 (or in the Foreward). Hopefully by the time we finish this
chapter everyone will have a copy of the book and we can proceed to the meat
of the book, starting with Chapter 2, with everyone on board.

Best regards

Rick
--
Richard S. Marken PhD
www.mindreadings.com

The only thing that will redeem mankind is cooperation.
                                                   -- Bertrand Russell

--
Richard S. Marken PhD
www.mindreadings.com

The only thing that will redeem mankind is cooperation.
                                                   -- Bertrand Russell