More Lego ev3 demos

[MartinT]

[Martin Taylor 2018.02.18,15.10]

But he didn't quote you, did he? I requote, with particular

emphases:
Yes, that is what I wrote, as quoted above.
The energy claims are indeed true, but I think irrelevant.
Equilibrium occurs when the restorative force (or more generally,
influence) is equal to the disturbing force, with no reference to
energy, since at every point in the movement from the
pre-disturbance equilibrium to the with-disturbance equilibrium, the
energy supplied by the disturbing influence is available for
restoration of the original state, allowing for the losses you
mention.
Why would you think there might be something wrong with it?
The truth of this is less evident. If you do an asymptotic analysis
of a control system with a reference value of zero, using the usual
symbols s_sensory input, p = perception, r=reference, e=error,
o=output, g = gain and d=disturbance you get:
p = s = o+d
  = ge + d
  = g(r-p) + d
p(1+g) = gr+d
p = (gr+d)/(1+g).
Set r = 0
p = d/(1+g)
p is proportional to d for all values of g.
Now, for the equilibrium system, asymptotically p = f(d). The
function f(.) depends on the physical structure. If the structure is
an ideal spring that obeys Hooke’s Law, then p is proportional to d,
and an appropriate choice of spring constant can produce
asymptotically the same result as the control system, no matter what
the value of g. Maybe the same is true of the leaky bucket, but I think some
manipulation of the definitions of disturbance and perception might
be required to make it true of the bowl, because the shape of the
bowl determines the vertical and horizontal components of the effect
of gravity as a function of height above the bowl bottom. If you
define the disturbing force to be horizontal, then it takes a very
specific bowl shape to make the asymptotic height proportional to d
(and what might “p” represent if not the height?). If you define
disturbance as force parallel to the bowl side and the force exceed
that of gravity (i.e. the weight of the ball), then the perceptual
value (the height of the ball) can go to infinity. The same is true
if d is a vertical force, except then either the ball doesn’t move
or it shoots up to infinity.
So sometimes there’s a mathematical identity between the asymptotic
results of control and of the operation of an equilibrium system,
sometimes there isn’t. But I think your point was more that there
could be mathematical identity between an equilibrium system and a
control system, rather than that they are always mathematically
equivalent (which you can indeed make happen by a careful choice to
f(.) and corresponding redefinition of d and p). It is less easy to
say that the dynamics of the two types of system are likely to
produce indistinguishable results, though again it is possible. All of this is rather beside the point, which has very little to do
with dynamics. A single control loop can be looked at in many ways,
especially if you ignore energy considerations. You can look at the
pure S-R nature of the internal processing, you can look at the
behavioural illusion that shows how the S-R processes must conform
to the nature of the environmental feedback path, you can look at
the emergent “control” property of the entire loop, you can compare
the output versus the perceptual sides of the loop, you can search
for the controlled variable. It is up to you. The point of PCT is that we do NOT much worry about single loops. As
soon as you get into multi-level control, everything changes. No
longer is a loop’s internal process identical to an S-R process.
Within a lower-level loop the variable reference value ensures that
control requires different outputs to achieve similar results. Apart
from that, multi-level control allows for “the same results by
different means”, which is very different from S-R.
Martin

···

On 2018/02/18 1:14 PM, Bruce Abbott
wrote:

        [From Bruce

Abbott (2018.02.18.1315 EST)]

Â

[Martin Taylor 2018.02.17.23.29]

              [Rick

Marken 2018-02-17_18:03:26]

Â

                    Â Bruce

Abbott (2018.02.17.1750 EST)–

                    ...

[RM] A negative feedback system (N system) is a
control system (see Powers, 1978). So if
equilibrium systems are N systems they are
control systems. But you say they are not
control systems because they don’t get their
disturbance resisting energy from an outside
source but, rather, from the disturbance itself
(per Richard’s criterion). But “disturbance
resistance” implies that there is a variable
being controlled.

      Why? Is the push of a ball up the side of a bowl not resisted

by gravity?

                    So

it sounds like you are saying that an
equilibrium system controls (in the sense that
is acts to resist disturbance to a controlled
variable) but it is not a control system because
it gets all its energy for this disturbance
resistance from the disturbance itself, which is
not enough energy to resist the disturbance.

      That last part "which is not enough energy to resist the

disturbance" has absolutely nothing to do with anything. You
brought it up out of your imagination, entire and complete.
The preceding part is also wrong: "it gets all its energy for
this disturbance resistance from the disturbance itself. Not
correct. The energy used by the disturbance in an equilibrium
system is stored as potential energy, which may be available
to restore the system to its initial state when the
disturbance goes to zero. It isn’t used in any way to “resist”
the disturbance. There is no such thing as “energy for
disturbance resistance” in this situation, in contrast to the
control situation in which there is.

Â

        Rick was

just quoting me about the restoring force in an equilibrium
system coming from the disturbance itself.Â

  So it sounds like you are saying that an

equilibrium system controls (in the sense that is acts to resist
disturbance to a controlled variable) but it is not a control
system because it gets all its energy
for this disturbance resistance from the disturbance itself, which
is not enough energy to resist the disturbance.

        If you push

the ball up the side of the bowl, thereby disturbing its
position relative to the bottom of the bowl, the energy you
expend is stored in the potential energy of the lifted
ball. When you remove the disturbance, this potential
energy gets converted to kinetic energy as gravity pulls the
ball back toward the bottom. This energy has “come from the
disturbance itselfâ€? rather than from some other source.Â
This restorative energy cannot exceed the energy that was
expended to lift the ball and in the absence of frictional
or other losses would exactly equal it.

Â

        In this

example it is the force of gravity, acting on the mass of
the ball, that supplies the resistance to the disturbing
force. Similarly, the energy expended to compress a spring
is stored in the spring. The spring resists being
compressed; once the compressing force is removed the force
stored in the compressed spring acts to restore the spring
to its former uncompressed state.

Â

        The classic

“leaky bucket� provides another example of an equilibrium
system. As the bucket fills, the water level in the bucket
rises, which increases the pressure exerted by the water on
the bottom of the bucket. This pressure forces water out
the hole in the bottom, and does so at an increasing rate as
the pressure increases. Eventually the rate at which the
water squirts out the bottom equals the rate at which the
water is being added, and the water-level stabilizes at that
equilibrium value. If increasing the flow of water into the
bucket is viewed as a disturbance to the water’s level, this
system resists that disturbance by increasing the rate at
which the water flows out of the hole as the water level in
the bucket rises further. If we then reduce the inflow back
to its previous value, the water level will return to its
pre-disturbance value. The extra pressure exerted by the
higher water level came from the disturbance (gravity acting
on the additional mass of water) and now acts to reduce the
water level until it reaches its former equilibrium value.

Â

        If there’s

something wrong with this analysis I’d like to hear about.

        Â 

Mathematically, this equates to a negative feedback system
with a gain of no more than 1.0.

Â

Bruce

[EetuP]

[Eetu Pikkarainen 2018-02-19_09:56:22 UTC]

[From Rupert Young (2018.02.18 18.15)]

Yes, exactly (Eetu also raised this) (though I think it’s just a matter of whether the motor goes forwards or backwards).
Whether the input reduces or increases is entirely dependent upon the environment, not the architecture (design) of the system. So, could this be said to be a control system?

I would say that it is a tragically bad control system, whose success of control depends on luck. With bad luck it runs with accelerating speed to fire when it tries to avoid heat. Bet perhaps
this is best you can get with only one sensor and one motor and nothing much more. With just an ability change the direction backwards if warmth is increasing it would be much better.

I think the crucial point here is that the design of Braitenberg’s Vehicles, and the whole of robotics, pretty much, is based upon a conceptual oversight.

Now, we could conceive of Vehicle 1 as a special, restricted case of a control system, where the reference is zero (the output is just to move). However, that is not at all readily apparent from the design. If we take that special case then the output
is a function of the error. The output, in this special case, is also a function of the input. However, only the latter is apparent from the design. So, the conceptual mistake that has been made is to not realise that the output is a function of the error
not of the input. Braitenberg made this conceptual error in Vehicle 1 and carried it on throughout his design of all the other vehicles. It is this same assumption that is made in robotics resulting in the perceived requirement for internal models.

As you say Vehicle 1 could have been designed differently. If it explicitly had a reference signal, which could be non-zero, e.g. such that the vehicle comes to rest at a particular temperature it would be obvious that the output (the speed) was a function
of the error and not the sensed input, i.e. it would explicitly be a perceptual control system. If that were the case then the design of all subsequent vehicles would have been very different. Unfortunately, Braitenberg’s book, which has been very influential
in robotics, has just perpetuated this conceptual error. The history of robotics could have been very different!

I see this conceptual point as very important and fundamental as depending upon which side of it one falls then it leads to very different architectures. One one hand complex input-output functions/models, on the other the relatively more simple perceptual
control system.

Braitenberg’s other vehicles were more complex dynamical systems, but I think rather than controlling a specific perception they would settle on various attractor points. If disturbed they may settle on a different attractor point. A perceptual control system
would always act to return to the same point.

That’s my take on it anyway.

That is a good point, I think! Control blindness is a case of conceptual blindness: If you cannot imagine that something could control then you cannot see it control
and you cannot build it to control.

Eetu

Regards,

Rupert

[rsmarken]

[Rick Marken 2018-02-19_09:48:29]

Rupert Young (2018.02.18 18.15)--

RY: With Vehicle 1 (<Notes On Vehicle 1: Getting Around) the output speed is proportional to the sensory input (in this case temperature). How does the effect of the output reduce the effect of the input?

RM: It depends on the direction of rotation of the wheel. If the wheel turns clockwise with the sensor to the right of the axle then movement of the wheel will move the sensor toward the heat source, increasing the heat at the sensor. So the effect of output on input is to increase the input effect on the output; there is positive feedback and the car will accelerate toward the heat source. No control:Â

RY: Yes, exactly (Eetu also raised this) (though I think it's just a matter of whether the motor goes forwards or backwards). Whether the input reduces or increases is entirely dependent upon the environment, not the architecture (design) of the system. So, could this be said to be a control system?

RM: It's a control system as long as increases in sensory input (heat) above zero cause increases in wheel velocity that move the vehicle away from the cause of the sensory input (the heat source) and decreases in sensory input below zero cause increases in wheel movement that move the vehicle toward the cause of the sensory input. With proper adjustment of gain and slowing this system will be stable and control sensed heat, keeping it at a perceptual level that corresponds to zero perceptual signal.Â
Â

RY: I think the crucial point here is that the design of Braitenberg's Vehicles, and the whole of robotics, pretty much, is based upon a conceptual oversight. Now, we could conceive of Vehicle 1 as a special, restricted case of a control system, where the reference is zero (the output is just to move). However, that is not at all readily apparent from the design. If we take that special case then the output is a function of the error. The output, in this special case, is also a function of the input. However, only the latter is apparent from the design. So, the conceptual mistake that has been made is to not realise that the output is a function of the error not of the input. Braitenberg made this conceptual error in Vehicle 1 and carried it on throughout his design of all the other vehicles. It is this same assumption that is made in robotics resulting in the perceived requirement for internal models.

RM: I agree with this. I think what PCT can do for robotics is provide a better conceptual orientation regarding what it means to get a robot to behave like a person. The orientation would be based on understanding that what are seen as consistently produced behaviors involved the control of perceptual variables (relative to secularly variable references) and those perceptual variables could be quite complex. If you want to design a system that produces a consistent sequence of outputs, for example, you have to design a perceptual function that can perceive the state of the sequence and do something about it if the sequence that is happening is not the desired sequence. That is, the design of robots should be largely oriented around the design of perceptual rather than output functions, though the latter are important too, of course. >

RY: I see this conceptual point as very important and fundamental as depending upon which side of it one falls then it leads to very different architectures. One one hand complex input-output functions/models, on the other the relatively more simple perceptual control system.

RM: Yes, I agree that the PCT conceptual orientation to robot design can result in more elegant architectures (you can certainly get rid of all the inverse kinematics for motion control, for example). But I also think the PCT orientation to design leads to serious consideration of the fact that the design of robots that can successfully carry out complex behaviors in the real world will require building perceptual functions that can perceive the state of the complex perceptual variables around which the observed behavior is organized. >

RY: Braitenberg's other vehicles were more complex dynamical systems, but I think rather than controlling a specific perception they would settle on various attractor points. If disturbed they may settle on a different attractor point. A perceptual control system would always act to return to the same point.

 RM: I think the people who build these vehicles are just being politically correct when they talk about "attractor points". Since these vehicles are control systems the reference state of the the variables they control are not attractor points (like the resting state of a pendulum or a mass on a spring); they are the reference states of controlled variables. The concept of attractor points is the politically correct way to refer to controlled (purposefully produced) results because it implies that these results can be produced by ordinary cause-effect processes. Â
BestÂ

···

On 17/02/2018 19:56, Richard Marken wrote:

That's my take on it anyway.

Regards,
Rupert

--
Richard S. MarkenÂ
"Perfection is achieved not when you have nothing more to add, but when you
have nothing left to take away.�
                --Antoine de Saint-Exupery

[wmansell]

Hi Alex, I think that’s a great point. A fruitful discussion about these system differences relies upon us being ‘at this level’ when discussing it?

···

[Rick Marken 2018-02-17_11:52:48]

Rupert Young (2018.02.16 16.30)–

RY: With Vehicle 1 (http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html )
the output speed is proportional to the sensory input
(in this case temperature). How does the effect of the
output reduce the effect of the input?

          RM: It depends on the direction of rotation of the

wheel. If the wheel turns clockwise with the sensor to the
right of the axle then movement of the wheel will move the
sensor toward the heat source, increasing the heat at the
sensor. So the effect of output on input is to increase
the input effect on the output; there is positive feedback
and the car will accelerate toward the heat source. No
control:

          RM: If, instead, the wheel turns counterclockwise

relative to the sensor on the right then movement of the
wheel caused by heat at the sensor moves the sensor away
from the heat reducing the effect of input on output; the
car eventually stops when the sensor is far enough from
the heat source that the input is zero; car stops when the
the input is at the virtual reference value, zero.

RY: Which Vehicle is this?

RM: One I saw as a student project.

                        RM: I think the line- following cars are

controlling the level of illumination in
each “eye”, trying to get it to zero; the
higher the illumination at an eye, the
greater the acceleration of the wheel on the
same side as the eye. So the car follows the
line by controlling for zero illumination in
both eyes, so that both wheels move at the
same velocity. That is, both eyes are
controlling for looking at the line. The
disturbance to this variable is the
curvature of the line. The car compensates
for this disturbance by accelerating the
wheel on the side of the car that is moving
off the line.

          RM: All control systems have the purpose of controlling

their inputs.

                          RY:

Rather I’d call them iterative
input-output systems, with the outputs
being continually updated based upon the
input states. They are certainly dynamic
systems, and, due to their complexity, appear
to do interesting things. But they are not
purposeful, in that they are not
controlling (perceptual) variables.

RY: What is the purpose within Vehicle 1?

          RM: If properly designed for stable negative feedback

(as I described above) vehicle 1 will control the heat
level at the sensor, maintaining it at a reference level
of zero.

                        RM: They are purposeful systems,

controlling the intensity of light in each
eye relative to a fixed reference
– zero. So they have a fixed purpose,
rather like Republicans whose fixed purpose
is quite obviously to destroy the country
for everyone except themselves and their
financial backers.

Alex Gomez-Marin
behavior-of-organisms.org

[Alex_Gomez-Marin]

so the phrasing “control system” can be misleading since it is not the system alone that makes itself be a control system or not, but its relation to the actual world it is in. the world changes, the system can stop being a control system. and the reverse too.

···

[Rick Marken 2018-02-17_11:52:48]

Rupert Young (2018.02.16 16.30)–

RY: With Vehicle 1 (http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html )
the output speed is proportional to the sensory input
(in this case temperature). How does the effect of the
output reduce the effect of the input?

          RM: It depends on the direction of rotation of the

wheel. If the wheel turns clockwise with the sensor to the
right of the axle then movement of the wheel will move the
sensor toward the heat source, increasing the heat at the
sensor. So the effect of output on input is to increase
the input effect on the output; there is positive feedback
and the car will accelerate toward the heat source. No
control:

          RM: If, instead, the wheel turns counterclockwise

relative to the sensor on the right then movement of the
wheel caused by heat at the sensor moves the sensor away
from the heat reducing the effect of input on output; the
car eventually stops when the sensor is far enough from
the heat source that the input is zero; car stops when the
the input is at the virtual reference value, zero.

RY: Which Vehicle is this?

RM: One I saw as a student project.

                        RM: I think the line- following cars are

controlling the level of illumination in
each “eye”, trying to get it to zero; the
higher the illumination at an eye, the
greater the acceleration of the wheel on the
same side as the eye. So the car follows the
line by controlling for zero illumination in
both eyes, so that both wheels move at the
same velocity. That is, both eyes are
controlling for looking at the line. The
disturbance to this variable is the
curvature of the line. The car compensates
for this disturbance by accelerating the
wheel on the side of the car that is moving
off the line.

          RM: All control systems have the purpose of controlling

their inputs.

                          RY:

Rather I’d call them iterative
input-output systems, with the outputs
being continually updated based upon the
input states. They are certainly dynamic
systems, and, due to their complexity, appear
to do interesting things. But they are not
purposeful, in that they are not
controlling (perceptual) variables.

RY: What is the purpose within Vehicle 1?

          RM: If properly designed for stable negative feedback

(as I described above) vehicle 1 will control the heat
level at the sensor, maintaining it at a reference level
of zero.

                        RM: They are purposeful systems,

controlling the intensity of light in each
eye relative to a fixed reference
– zero. So they have a fixed purpose,
rather like Republicans whose fixed purpose
is quite obviously to destroy the country
for everyone except themselves and their
financial backers.

Alex Gomez-Marin
behavior-of-organisms.org

[EetuP]

[Eetu Pikkarainen 2018-02-21_09:07:00 UTC]

We had a psychology professor who was developing a theory of “organism-environment systems�. There is (after all) some sense in it. Isn’t it so that the feedback chain is part of the control system even though it is not
part of the organism? This talk becomes problematic if we think about an assumed elementary control system inside the control hierarchy: every elementary control system (ECU) seems to contain the whole hierarchy below it, the other ECUs and the environmental
feedback chain. But anyway, control system is a loop and so part of it is in its environment and thus outside of it…

Eetu

···

so the phrasing “control system” can be misleading since it is not the system alone that makes itself be a control system or not, but its relation to the actual world it is in. the world changes, the system can stop being
a control system. and the reverse too.

On Wed, 21 Feb 2018 at 09:25, Warren Mansell wmansell@gmail.com wrote:

Hi Alex, I think that’s a great point. A fruitful discussion about these system differences relies upon us being ‘at this level’ when discussing it?

On 18 Feb 2018, at 18:35, Alex Gomez-Marin agomezmarin@gmail.com wrote:

one of my comments got lost: a braitenberg or any other system is a control system depending also on the environment since N-systems are so by virtue of properties of both the f and the g function, so it is a organism-world relational property.

On Sun, 18 Feb 2018 at 19:16, Rupert Young rupert@perceptualrobots.com wrote:

[From Rupert Young (2018.02.18 18.15)]

On 17/02/2018 19:56, Richard Marken wrote:

[Rick Marken 2018-02-17_11:52:48]

Rupert Young (2018.02.16 16.30)–

RY: With Vehicle 1 (http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html )
the output speed is proportional to the sensory input (in this case temperature). How does the effect of the output reduce the effect of the input?

RM: It depends on the direction of rotation of the wheel. If the wheel turns clockwise with the sensor to the right of the axle then movement of the wheel will move the sensor toward the heat source, increasing the heat at the sensor. So
the effect of output on input is to increase the input effect on the output; there is positive feedback and the car will accelerate toward the heat source. No control:

Yes, exactly (Eetu also raised this) (though I think it’s just a matter of whether the motor goes forwards or backwards). Whether the input reduces or increases is entirely dependent upon the environment, not the architecture (design) of
the system. So, could this be said to be a control system?

RM: If, instead, the wheel turns counterclockwise relative to the sensor on the right then movement of the wheel caused by heat at the sensor moves the sensor away from the heat reducing the effect of input on output; the car eventually
stops when the sensor is far enough from the heat source that the input is zero; car stops when the the input is at the virtual reference value, zero.

RM: I think the line- following cars are controlling the level of illumination in each “eye”, trying to get it to zero; the higher the illumination at an eye, the greater the acceleration of the wheel on the same side as the eye. So the
car follows the line by controlling for zero illumination in both eyes, so that both wheels move at the same velocity. That is, both eyes are controlling for looking at the line. The disturbance to this variable is the curvature of the line. The car compensates
for this disturbance by accelerating the wheel on the side of the car that is moving off the line.

RY: Which Vehicle is this?

RM: One I saw as a student project.

My comments were specifically about Braitenberg’s Vehicles. Some of them may be PCT systems, but more by accident than by design.

RY: Rather I’d call them iterative input-output systems, with the outputs being continually updated based upon the input states. They are certainly dynamic systems, and, due to their complexity,
appear to do interesting things. But they are not purposeful, in that they are not controlling (perceptual) variables.

RM: All control systems have the purpose of controlling their inputs.

Well, yes, but are Braitenberg’s Vehicles control systems? Your comment above “No control” suggests not, necessarily.

RM: They are purposeful systems, controlling the intensity of light in each eye relative to a
fixed reference – zero. So they have a fixed purpose, rather like Republicans whose fixed purpose is quite obviously to destroy the country for everyone except themselves and their financial backers.

RY: What is the purpose within Vehicle 1?

RM: If properly designed for stable negative feedback (as I described above) vehicle 1 will control the heat level at the sensor, maintaining it at a reference level of zero.

Well, yes, but my question was about the current design of Vehicle 1, not if you change the design.

I think the crucial point here is that the design of Braitenberg’s Vehicles, and the whole of robotics, pretty much, is based upon a conceptual oversight. Now, we could conceive of Vehicle 1 as a special, restricted case of a control system, where the reference
is zero (the output is just to move). However, that is not at all readily apparent from the design. If we take that special case then the output is a function of the error. The output, in this special case, is also a function of the input. However, only the
latter is apparent from the design. So, the conceptual mistake that has been made is to not realise that the output is a function of the error not of the input. Braitenberg made this conceptual error in Vehicle 1 and carried it on throughout his design of
all the other vehicles. It is this same assumption that is made in robotics resulting in the perceived requirement for internal models.

As you say Vehicle 1 could have been designed differently. If it explicitly had a reference signal, which could be non-zero, e.g. such that the vehicle comes to rest at a particular temperature it would be obvious that the output (the speed) was a function
of the error and not the sensed input, i.e. it would explicitly be a perceptual control system. If that were the case then the design of all subsequent vehicles would have been very different. Unfortunately, Braitenberg’s book, which has been very influential
in robotics, has just perpetuated this conceptual error. The history of robotics could have been very different!

I see this conceptual point as very important and fundamental as depending upon which side of it one falls then it leads to very different architectures. One one hand complex input-output functions/models, on the other the relatively more simple perceptual
control system.

Braitenberg’s other vehicles were more complex dynamical systems, but I think rather than controlling a specific perception they would settle on various attractor points. If disturbed they may settle on a different attractor point. A perceptual control system
would always act to return to the same point.

That’s my take on it anyway.

Regards,
Rupert

–

Alex Gomez-Marin
behavior-of-organisms.org

–

Alex Gomez-Marin
behavior-of-organisms.org

[MartinT]

[Martin Taylor 2018.02.21.11.09]

I have always found it useful to distinguish in PCT the concepts of

“Elementary Control Unit” (ECU) from “Control Loop” or “Control
System”. A “unit” is a conglomeration of items that are useful
together. A “loop” is a particular structure. A “system” is a
structure of any form that functions in some describable way. I find
it helps to use the three words preceded by the adjectival “control”
in those same distinct ways.
An ECU consists of internal components specific to a particular
perception at one and only one level. In PCT, those are typically a
Perceptual Input Function, a Reference Input Function, a Comparator,
and an Output Function. A Control Loop includes an ECU and an
environmental feedback path, which may include components both
within the organism (lower level control loops and processes) and
outside the organism (External environmental feedback paths). An ECU is not a control system or a control loop. Its connection
pattern to lower levels may make it part of one, if the resulting
path through the external real reality (not the perceived external
reality) and the intervening processing layers allows its perception
to be controlled. As I have said before: “Control” is an emergent
property of a particular structure that includes at least an ECU and
an environmental feedback path that includes a property of the
external environment or within the organism that can be both
influenced and perceived by the corresponding elements of the ECU.
Martin

···

On 2018/02/21 4:02 AM, Alex Gomez-Marin
wrote:

      so the phrasing "control system" can be

misleading since it is not the system alone that makes itself
be a control system or not, but its relation to the actual
world it is in. the world changes, the system can stop being a
control system. and the reverse too.

On Wed, 21 Feb 2018 at 09:25, Warren Mansell <wmansell@gmail.com >
wrote:

            Hi Alex, I think that’s a great point. A fruitful

discussion about these system differences relies upon us
being ‘at this level’ when discussing it?

            On 18 Feb 2018, at 18:35, Alex Gomez-Marin <agomezmarin@gmail.com                >

wrote:

                  one of my comments got lost: a

braitenberg or any other system is a control
system depending also on the environment since
N-systems are so by virtue of properties of both
the f and the g function, so it is a
organism-world relational property.

                    On Sun, 18 Feb 2018 at 19:16, Rupert Young

<rupert@perceptualrobots.com >
wrote:

[From Rupert Young (2018.02.18 18.15)]

                        On

17/02/2018 19:56, Richard Marken wrote:

                              [Rick Marken

2018-02-17_11:52:48]

                                    Rupert Young (2018.02.16

16.30)–

RY: With Vehicle 1 (http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html )
the output speed is proportional
to the sensory input (in this case
temperature). How does the effect
of the output reduce the effect of
the input?

                                RM: It depends on the direction

of rotation of the wheel. If the
wheel turns clockwise with the
sensor to the right of the axle then
movement of the wheel will move the
sensor toward the heat source,
increasing the heat at the sensor.
So the effect of output on input is
to increase the input effect on the
output; there is positive feedback
and the car will accelerate toward
the heat source. No control:

                      Yes,

exactly (Eetu also raised this) (though I
think it’s just a matter of whether the motor
goes forwards or backwards). Whether the input
reduces or increases is entirely dependent
upon the environment, not the architecture
(design) of the system. So, could this be said
to be a control system?

                                RM: If, instead, the wheel turns

counterclockwise relative to the
sensor on the right then movement of
the wheel caused by heat at the
sensor moves the sensor away from
the heat reducing the effect of
input on output; the car eventually
stops when the sensor is far enough
from the heat source that the input
is zero; car stops when the the
input is at the virtual reference
value, zero.

                                              RM: I think the

line- following cars
are controlling the
level of illumination
in each “eye”, trying
to get it to zero; the
higher the
illumination at an
eye, the greater the
acceleration of the
wheel on the same side
as the eye. So the car
follows the line by
controlling for zero
illumination in both
eyes, so that both
wheels move at the
same velocity. That
is, both eyes are
controlling for
looking at the line.
The disturbance to
this variable is the
curvature of the line.
The car compensates
for this disturbance
by accelerating the
wheel on the side of
the car that is moving
off the line.

RY: Which Vehicle is this?

                                RM: One I saw as a student

project.

                      My

comments were specifically about Braitenberg’s
Vehicles. Some of them may be PCT systems, but
more by accident than by design.

                                                RY:

Rather I’d call them
iterative
input-output
systems, with the
outputs being
continually updated
based upon the input
states. They are
certainly dynamic
systems, and, due to
their complexity, appear
to do interesting
things. But they are
not purposeful, in
that they are not
controlling
(perceptual)
variables.

                                RM: All control systems have the

purpose of controlling their
inputs.

                      Well,

yes, but are Braitenberg’s Vehicles control
systems? Your comment above “No control”
suggests not, necessarily.

                                              RM: They are

purposeful systems,
controlling the
intensity of light in
each eye relative to a
fixed reference
– zero. So they have
a fixed purpose,
rather like
Republicans whose
fixed purpose is quite
obviously to destroy
the country for
everyone except
themselves and their
financial backers.

                                  RY: What is the purpose

within Vehicle 1?

                                RM: If properly designed for

stable negative feedback (as I
described above) vehicle 1 will
control the heat level at the
sensor, maintaining it at a
reference level of zero.

                      Well,

yes, but my question was about the current
design of Vehicle 1, not if you change the
design.

                      I think the crucial point here is that the

design of Braitenberg’s Vehicles, and the
whole of robotics, pretty much, is based upon
a conceptual oversight. Now, we could conceive
of Vehicle 1 as a special, restricted case of
a control system, where the reference is zero
(the output is just to move). However, that is
not at all readily apparent from the design.
If we take that special case then the output
is a function of the error. The output, in
this special case, is also a function of the
input. However, only the latter is apparent
from the design. So, the conceptual mistake
that has been made is to not realise that the
output is a function of the error not of the
input. Braitenberg made this conceptual error
in Vehicle 1 and carried it on throughout his
design of all the other vehicles. It is this
same assumption that is made in robotics
resulting in the perceived requirement for
internal models.

                      As you say Vehicle 1 could have been designed

differently. If it explicitly had a reference
signal, which could be non-zero, e.g. such
that the vehicle comes to rest at a particular
temperature it would be obvious that the
output (the speed) was a function of the error
and not the sensed input, i.e. it would
explicitly be a perceptual control system. If
that were the case then the design of all
subsequent vehicles would have been very
different. Unfortunately, Braitenberg’s book,
which has been very influential in robotics,
has just perpetuated this conceptual error.
The history of robotics could have been very
different!

                      I see this conceptual point as very important

and fundamental as depending upon which side
of it one falls then it leads to very
different architectures. One one hand complex
input-output functions/models, on the other
the relatively more simple perceptual control
system.

                      Braitenberg's other vehicles were more complex

dynamical systems, but I think rather than
controlling a specific perception they would
settle on various attractor points. If
disturbed they may settle on a different
attractor point. A perceptual control system
would always act to return to the same point.

                      That's my take on it anyway.



                      Regards,

                      Rupert

–

Alex Gomez-Marin

                [behavior-of-organisms.org](http://behavior-of-organisms.org)

–
Alex Gomez-Marin

    [behavior-of-organisms.org](http://behavior-of-organisms.org)

[EetuP]

[Eetu Pikkarainen 2018-02-22_07:28:20 UTC]

Thanks Martin, that makes much sense. I tried to use those concepts in my reply but I mixed them up. Now I am wiser.

As for the Alex’s issue, an organism or a device may be a structured collection of (one or more) ECUs but whether it forms a control system depends on whether it has
a proper feedback path. If the environment doesn’t offer a functioning feedback path then it is only a potential control system.

(I think this issue should have some consequences for our traditional existential self-understanding as beings restricted inside the skin.)

···

Eetu

[Martin Taylor 2018.02.21.11.09]

On 2018/02/21 4:02 AM, Alex Gomez-Marin wrote:

so the phrasing “control system” can be misleading since it is not the system alone that makes itself be a control system or not, but its relation to the actual world it is in. the world changes, the system can stop being a control system.
and the reverse too.

I have always found it useful to distinguish in PCT the concepts of “Elementary Control Unit” (ECU) from “Control Loop” or “Control System”. A “unit” is a conglomeration of items that are useful together. A “loop” is a particular structure. A “system” is a
structure of any form that functions in some describable way. I find it helps to use the three words preceded by the adjectival “control” in those same distinct ways.

An ECU consists of internal components specific to a particular perception at one and only one level. In PCT, those are typically a Perceptual Input Function, a Reference Input Function, a Comparator, and an Output Function. A Control Loop includes an ECU and
an environmental feedback path, which may include components both within the organism (lower level control loops and processes) and outside the organism (External environmental feedback paths).

An ECU is not a control system or a control loop. Its connection pattern to lower levels may make it part of one, if the resulting path through the external real reality (not the perceived external reality) and the intervening processing layers allows its perception
to be controlled. As I have said before: “Control” is an emergent property of a particular structure that includes at least an ECU and an environmental feedback path that includes a property of the external environment or within the organism that can be both
influenced and perceived by the corresponding elements of the ECU.

Martin

On Wed, 21 Feb 2018 at 09:25, Warren Mansell wmansell@gmail.com wrote:

Hi Alex, I think that’s a great point. A fruitful discussion about these system differences relies upon us being ‘at this level’ when discussing it?

On 18 Feb 2018, at 18:35, Alex Gomez-Marin agomezmarin@gmail.com wrote:

one of my comments got lost: a braitenberg or any other system is a control system depending also on the environment since N-systems are so by virtue of properties of both the f and the g function, so it is a organism-world relational property.

On Sun, 18 Feb 2018 at 19:16, Rupert Young rupert@perceptualrobots.com wrote:

[From Rupert Young (2018.02.18 18.15)]

On 17/02/2018 19:56, Richard Marken wrote:

[Rick Marken 2018-02-17_11:52:48]

Rupert Young (2018.02.16 16.30)–

RY: With Vehicle 1 (http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html )
the output speed is proportional to the sensory input (in this case temperature). How does the effect of the output reduce the effect of the input?

RM: It depends on the direction of rotation of the wheel. If the wheel turns clockwise with the sensor to the right of the axle then movement of the wheel will move the sensor toward the heat source, increasing the heat at the sensor. So
the effect of output on input is to increase the input effect on the output; there is positive feedback and the car will accelerate toward the heat source. No control:

Yes, exactly (Eetu also raised this) (though I think it’s just a matter of whether the motor goes forwards or backwards). Whether the input reduces or increases is entirely dependent upon the environment, not the architecture (design) of
the system. So, could this be said to be a control system?

RM: If, instead, the wheel turns counterclockwise relative to the sensor on the right then movement of the wheel caused by heat at the sensor moves the sensor away from the heat reducing the effect of input on output; the car eventually
stops when the sensor is far enough from the heat source that the input is zero; car stops when the the input is at the virtual reference value, zero.

RM: I think the line- following cars are controlling the level of illumination in each “eye”, trying to get it to zero; the higher the illumination at an eye, the greater the acceleration of the wheel on the same side as the eye. So the
car follows the line by controlling for zero illumination in both eyes, so that both wheels move at the same velocity. That is, both eyes are controlling for looking at the line. The disturbance to this variable is the curvature of the line. The car compensates
for this disturbance by accelerating the wheel on the side of the car that is moving off the line.

RY: Which Vehicle is this?

RM: One I saw as a student project.

My comments were specifically about Braitenberg’s Vehicles. Some of them may be PCT systems, but more by accident than by design.

RY: Rather I’d call them iterative input-output systems, with the outputs being continually updated based upon the input states. They are certainly dynamic systems, and, due to their complexity,
appear to do interesting things. But they are not purposeful, in that they are not controlling (perceptual) variables.

RM: All control systems have the purpose of controlling their inputs.

Well, yes, but are Braitenberg’s Vehicles control systems? Your comment above “No control” suggests not, necessarily.

RM: They are purposeful systems, controlling the intensity of light in each eye relative to a
fixed reference – zero. So they have a fixed purpose, rather like Republicans whose fixed purpose is quite obviously to destroy the country for everyone except themselves and their financial backers.

RY: What is the purpose within Vehicle 1?

RM: If properly designed for stable negative feedback (as I described above) vehicle 1 will control the heat level at the sensor, maintaining it at a reference level of zero.

Well, yes, but my question was about the current design of Vehicle 1, not if you change the design.

I think the crucial point here is that the design of Braitenberg’s Vehicles, and the whole of robotics, pretty much, is based upon a conceptual oversight. Now, we could conceive of Vehicle 1 as a special, restricted case of a control system, where the reference
is zero (the output is just to move). However, that is not at all readily apparent from the design. If we take that special case then the output is a function of the error. The output, in this special case, is also a function of the input. However, only the
latter is apparent from the design. So, the conceptual mistake that has been made is to not realise that the output is a function of the error not of the input. Braitenberg made this conceptual error in Vehicle 1 and carried it on throughout his design of
all the other vehicles. It is this same assumption that is made in robotics resulting in the perceived requirement for internal models.

As you say Vehicle 1 could have been designed differently. If it explicitly had a reference signal, which could be non-zero, e.g. such that the vehicle comes to rest at a particular temperature it would be obvious that the output (the speed) was a function
of the error and not the sensed input, i.e. it would explicitly be a perceptual control system. If that were the case then the design of all subsequent vehicles would have been very different. Unfortunately, Braitenberg’s book, which has been very influential
in robotics, has just perpetuated this conceptual error. The history of robotics could have been very different!

I see this conceptual point as very important and fundamental as depending upon which side of it one falls then it leads to very different architectures. One one hand complex input-output functions/models, on the other the relatively more simple perceptual
control system.

Braitenberg’s other vehicles were more complex dynamical systems, but I think rather than controlling a specific perception they would settle on various attractor points. If disturbed they may settle on a different attractor point. A perceptual control system
would always act to return to the same point.

That’s my take on it anyway.

Regards,
Rupert

–

Alex Gomez-Marin
behavior-of-organisms.org

–

Alex Gomez-Marin
behavior-of-organisms.org

[Alex_Gomez-Marin]

Indeed: we are not a simply a hierarchy of control loops in a brain, but the brain has a body, and the body is in the world, and the world (and the brain, and the body) are dynamical. A more process-oriented ontology makes more justice to the phenomenon than the usual “brain in a vat” kind of thinking, be it in open or closed loop.

···

On Thu, Feb 22, 2018 at 8:45 AM, Eetu Pikkarainen eetu.pikkarainen@oulu.fi wrote:

[Eetu Pikkarainen 2018-02-22_07:28:20 UTC]

Thanks Martin, that makes much sense. I tried to use those concepts in my reply but I mixed them up. Now I am wiser.

As for the Alex’s issue, an organism or a device may be a structured collection of (one or more) ECUs but whether it forms a control system depends on whether it has
a proper feedback path. If the environment doesn’t offer a functioning feedback path then it is only a potential control system.

(I think this issue should have some consequences for our traditional existential self-understanding as beings restricted inside the skin.)

Eetu

[Martin Taylor 2018.02.21.11.09]

On 2018/02/21 4:02 AM, Alex Gomez-Marin wrote:

so the phrasing “control system” can be misleading since it is not the system alone that makes itself be a control system or not, but its relation to the actual world it is in. the world changes, the system can stop being a control system.
and the reverse too.

I have always found it useful to distinguish in PCT the concepts of “Elementary Control Unit” (ECU) from “Control Loop” or “Control System”. A “unit” is a conglomeration of items that are useful together. A “loop” is a particular structure. A “system” is a
structure of any form that functions in some describable way. I find it helps to use the three words preceded by the adjectival “control” in those same distinct ways.

An ECU consists of internal components specific to a particular perception at one and only one level. In PCT, those are typically a Perceptual Input Function, a Reference Input Function, a Comparator, and an Output Function. A Control Loop includes an ECU and
an environmental feedback path, which may include components both within the organism (lower level control loops and processes) and outside the organism (External environmental feedback paths).

An ECU is not a control system or a control loop. Its connection pattern to lower levels may make it part of one, if the resulting path through the external real reality (not the perceived external reality) and the intervening processing layers allows its perception
to be controlled. As I have said before: “Control” is an emergent property of a particular structure that includes at least an ECU and an environmental feedback path that includes a property of the external environment or within the organism that can be both
influenced and perceived by the corresponding elements of the ECU.

Martin

On Wed, 21 Feb 2018 at 09:25, Warren Mansell wmansell@gmail.com wrote:

Hi Alex, I think that’s a great point. A fruitful discussion about these system differences relies upon us being ‘at this level’ when discussing it?

On 18 Feb 2018, at 18:35, Alex Gomez-Marin agomezmarin@gmail.com wrote:

one of my comments got lost: a braitenberg or any other system is a control system depending also on the environment since N-systems are so by virtue of properties of both the f and the g function, so it is a organism-world relational property.

On Sun, 18 Feb 2018 at 19:16, Rupert Young rupert@perceptualrobots.com wrote:

[From Rupert Young (2018.02.18 18.15)]

On 17/02/2018 19:56, Richard Marken wrote:

[Rick Marken 2018-02-17_11:52:48]

Rupert Young (2018.02.16 16.30)–

RY: With Vehicle 1 (http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html )
the output speed is proportional to the sensory input (in this case temperature). How does the effect of the output reduce the effect of the input?

RM: It depends on the direction of rotation of the wheel. If the wheel turns clockwise with the sensor to the right of the axle then movement of the wheel will move the sensor toward the heat source, increasing the heat at the sensor. So
the effect of output on input is to increase the input effect on the output; there is positive feedback and the car will accelerate toward the heat source. No control:

Yes, exactly (Eetu also raised this) (though I think it’s just a matter of whether the motor goes forwards or backwards). Whether the input reduces or increases is entirely dependent upon the environment, not the architecture (design) of
the system. So, could this be said to be a control system?

RM: If, instead, the wheel turns counterclockwise relative to the sensor on the right then movement of the wheel caused by heat at the sensor moves the sensor away from the heat reducing the effect of input on output; the car eventually
stops when the sensor is far enough from the heat source that the input is zero; car stops when the the input is at the virtual reference value, zero.

RM: I think the line- following cars are controlling the level of illumination in each “eye”, trying to get it to zero; the higher the illumination at an eye, the greater the acceleration of the wheel on the same side as the eye. So the
car follows the line by controlling for zero illumination in both eyes, so that both wheels move at the same velocity. That is, both eyes are controlling for looking at the line. The disturbance to this variable is the curvature of the line. The car compensates
for this disturbance by accelerating the wheel on the side of the car that is moving off the line.

RY: Which Vehicle is this?

RM: One I saw as a student project.

My comments were specifically about Braitenberg’s Vehicles. Some of them may be PCT systems, but more by accident than by design.

RY: Rather I’d call them iterative input-output systems, with the outputs being continually updated based upon the input states. They are certainly dynamic systems, and, due to their complexity,
appear to do interesting things. But they are not purposeful, in that they are not controlling (perceptual) variables.

RM: All control systems have the purpose of controlling their inputs.

Well, yes, but are Braitenberg’s Vehicles control systems? Your comment above “No control” suggests not, necessarily.

RM: They are purposeful systems, controlling the intensity of light in each eye relative to a
fixed reference – zero. So they have a fixed purpose, rather like Republicans whose fixed purpose is quite obviously to destroy the country for everyone except themselves and their financial backers.

RY: What is the purpose within Vehicle 1?

RM: If properly designed for stable negative feedback (as I described above) vehicle 1 will control the heat level at the sensor, maintaining it at a reference level of zero.

Well, yes, but my question was about the current design of Vehicle 1, not if you change the design.

I think the crucial point here is that the design of Braitenberg’s Vehicles, and the whole of robotics, pretty much, is based upon a conceptual oversight. Now, we could conceive of Vehicle 1 as a special, restricted case of a control system, where the reference
is zero (the output is just to move). However, that is not at all readily apparent from the design. If we take that special case then the output is a function of the error. The output, in this special case, is also a function of the input. However, only the
latter is apparent from the design. So, the conceptual mistake that has been made is to not realise that the output is a function of the error not of the input. Braitenberg made this conceptual error in Vehicle 1 and carried it on throughout his design of
all the other vehicles. It is this same assumption that is made in robotics resulting in the perceived requirement for internal models.

As you say Vehicle 1 could have been designed differently. If it explicitly had a reference signal, which could be non-zero, e.g. such that the vehicle comes to rest at a particular temperature it would be obvious that the output (the speed) was a function
of the error and not the sensed input, i.e. it would explicitly be a perceptual control system. If that were the case then the design of all subsequent vehicles would have been very different. Unfortunately, Braitenberg’s book, which has been very influential
in robotics, has just perpetuated this conceptual error. The history of robotics could have been very different!

I see this conceptual point as very important and fundamental as depending upon which side of it one falls then it leads to very different architectures. One one hand complex input-output functions/models, on the other the relatively more simple perceptual
control system.

Braitenberg’s other vehicles were more complex dynamical systems, but I think rather than controlling a specific perception they would settle on various attractor points. If disturbed they may settle on a different attractor point. A perceptual control system
would always act to return to the same point.

That’s my take on it anyway.

Regards,
Rupert

–

Alex Gomez-Marin
behavior-of-organisms.org

–

Alex Gomez-Marin
behavior-of-organisms.org

[rupert]

[From Rupert Young (2018.02.22 16.00)]

one of my comments got lost: a braitenberg or any other system is a control system depending also on the environment since N-systems are so by virtue of properties of both the f and the g function, so it is a organism-world relational property.

Sure, though, I guess, it depends on the definition of "control system". Is a positive feedback system a control system?

There has been some discussion on csgnet on this topic this month. Was it boiled down to a formal definition? Is a power drill a control system? Is a thermostat in its box a control system?

Regards,
Rupert

···

On 18/02/2018 18:35, Alex Gomez-Marin wrote:

[rupert]

[From Rupert Young (2018.02.22 16.05)]

(Rick Marken 2018-02-19_09:48:29]

This system would run straight into a heat source (if it were

straight ahead), so does that mean it is not a control system?

I agree, partially. Controlled results are attractor points within

dynamical systems. But not all attractor points within dynamical
systems are controlled results. For example, the predator/prey
relationship between penguins and seals may stabilise at a certain
value. It is an attractor point within a dynamical system, but it is
not a controlled result. Add a disturbance with a bunch of polar
bears to the environment and the relationship between penguins and
seals would probably stabilise at a different value; i.e. a
different attractor point. I think this is what Braitenberg’s
vehicles are like, rather than a perceptual control system, which
would oppose disturbances to return to the same “attractor point”.

Regards,

Rupert

···

Rupert Young (2018.02.18 18.15)–

                On

17/02/2018 19:56, Richard Marken wrote:

            RY: Yes, exactly (Eetu also raised this) (though

I think it’s just a matter of whether the motor goes
forwards or backwards). Whether the input reduces or
increases is entirely dependent upon the environment,
not the architecture (design) of the system. So, could
this be said to be a control system?

          RM: It's a control system as long as increases in

sensory input (heat) above zero cause increases in wheel
velocity that move the vehicle away from the cause
of the sensory input (the heat source) and decreases in
sensory input below zero cause increases in wheel movement
that move the vehicle toward the cause of the
sensory input. With proper adjustment of gain and slowing
this system will be stable and control sensed heat,
keeping it at a perceptual level that corresponds to zero
perceptual signal.

                          RY:

With Vehicle 1 (http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html )
the output speed is proportional to the
sensory input (in this case temperature).
How does the effect of the output reduce
the effect of the input?

                        RM: It depends on the direction of

rotation of the wheel. If the wheel turns
clockwise with the sensor to the right of
the axle then movement of the wheel will
move the sensor toward the heat source,
increasing the heat at the sensor. So the
effect of output on input is to increase the
input effect on the output; there is
positive feedback and the car will
accelerate toward the heat source. No
control:

            RY: Braitenberg's

other vehicles were more complex dynamical systems, but
I think rather than controlling a specific perception
they would settle on various attractor points. If
disturbed they may settle on a different attractor
point. A perceptual control system would always act to
return to the same point.

          RM: I think the people who build these vehicles are

just being politically correct when they talk about
“attractor points”. Since these vehicles are control
systems the reference state of the the variables they
control are not attractor points (like the resting state
of a pendulum or a mass on a spring); they are the
reference states of controlled variables. The concept of attractor
points is the politically correct way to refer to
controlled (purposefully produced) results because it
implies that these results can be produced by ordinary
cause-effect processes.

[PHILIP_JERAIR_YERANO]

Re Bruce
Please direct me to the book or publication describing Bill Power’s “Crowdâ€? demo in “Lorenzâ€? mode.Â

···

On Thu, Feb 22, 2018 at 8:04 AM, Rupert Young rupert@perceptualrobots.com wrote:

[From Rupert Young (2018.02.22 16.05)]

(Rick Marken 2018-02-19_09:48:29]

This system would run straight into a heat source (if it were

straight ahead), so does that mean it is not a control system?

 

I agree, partially. Controlled results are attractor points within

dynamical systems. But not all attractor points within dynamical
systems are controlled results. For example, the predator/prey
relationship between penguins and seals may stabilise at a certain
value. It is an attractor point within a dynamical system, but it is
not a controlled result. Add a disturbance with a bunch of polar
bears to the environment and the relationship between penguins and
seals would probably stabilise at a different value; i.e. a
different attractor point. I think this is what Braitenberg’s
vehicles are like, rather than a perceptual control system, which
would oppose disturbances to return to the same “attractor point”.

Regards,

Rupert

Rupert Young (2018.02.18 18.15)–

                On

17/02/2018 19:56, Richard Marken wrote:

            RY: Yes, exactly (Eetu also raised this) (though

I think it’s just a matter of whether the motor goes
forwards or backwards). Whether the input reduces or
increases is entirely dependent upon the environment,
not the architecture (design) of the system. So, could
this be said to be a control system?

          RM: It's a control system as long as increases in

sensory input (heat) above zero cause increases in wheel
velocity that move the vehicle away from the cause
of the sensory input (the heat source) and decreases in
sensory input below zero cause increases in wheel movement
that move the vehicle toward the cause of the
sensory input. With proper adjustment of gain and slowing
this system will be stable and control sensed heat,
keeping it at a perceptual level that corresponds to zero
perceptual signal.

                          RY:

With Vehicle 1 (http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html )
the output speed is proportional to the
sensory input (in this case temperature).
How does the effect of the output reduce
the effect of the input?

                        RM: It depends on the direction of

rotation of the wheel. If the wheel turns
clockwise with the sensor to the right of
the axle then movement of the wheel will
move the sensor toward the heat source,
increasing the heat at the sensor. So the
effect of output on input is to increase the
input effect on the output; there is
positive feedback and the car will
accelerate toward the heat source. No
control:Â

            RY: Braitenberg's

other vehicles were more complex dynamical systems, but
I think rather than controlling a specific perception
they would settle on various attractor points. If
disturbed they may settle on a different attractor
point. A perceptual control system would always act to
return to the same point.

          Â RM: I think the people who build these vehicles are

just being politically correct when they talk about
“attractor points”. Since these vehicles are control
systems the reference state of the the variables they
control are not attractor points (like the resting state
of a pendulum or a mass on a spring); they are the
reference states of controlled variables. The concept of attractor
points is the politically correct way to refer to
controlled (purposefully produced) results because it
implies that these results can be produced by ordinary
cause-effect processes.Â

[MartinT]

Philip,

  Since you don't identify your two messages today, I will do you

the same (dis)courtesy, and since you make a request to Bruce in a
reply to Rupert, I will be Bruce for you and answer your question:
The “Konrad” demo in Chapter 9 of LCS III.

Martin

···

On 2018/02/22 1:39 PM, PHILIP JERAIR
YERANOSIAN wrote:

Re Bruce

    Please direct me to the book or publication describing           Bill

Power’s “Crowdâ€? demo in “Lorenzâ€? mode.Â

      On Thu, Feb 22, 2018 at 8:04 AM, Rupert

Young rupert@perceptualrobots.com
wrote:

[From Rupert Young (2018.02.22 16.05)]

(Rick Marken 2018-02-19_09:48:29]

Rupert Young (2018.02.18 18.15)–

                            On

17/02/2018 19:56, Richard Marken wrote:

                                      RY: With

Vehicle 1 (http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html )
the output speed is
proportional to the sensory
input (in this case
temperature). How does the
effect of the output reduce
the effect of the input?

                                    RM: It depends on the

direction of rotation of the
wheel. If the wheel turns
clockwise with the sensor to the
right of the axle then movement
of the wheel will move the
sensor toward the heat source,
increasing the heat at the
sensor. So the effect of output
on input is to increase the
input effect on the output;
there is positive feedback and
the car will accelerate toward
the heat source. No control:Â

                        RY: Yes, exactly (Eetu also raised

this) (though I think it’s just a matter of
whether the motor goes forwards or
backwards). Whether the input reduces or
increases is entirely dependent upon the
environment, not the architecture (design)
of the system. So, could this be said to be
a control system?

                      RM: It's a control system as long as

increases in sensory input (heat) above zero
cause increases in wheel velocity that move
the vehicle away from the cause of the
sensory input (the heat source) and decreases
in sensory input below zero cause increases in
wheel movement that move the vehicle toward
the cause of the sensory input. With proper
adjustment of gain and slowing this system
will be stable and control sensed heat,
keeping it at a perceptual level that
corresponds to zero perceptual signal.

           This system would run straight into a heat source

(if it were straight ahead), so does that mean it is not a
control system?

            Â 

                        RY:

Braitenberg’s other vehicles were more
complex dynamical systems, but I think
rather than controlling a specific
perception they would settle on various
attractor points. If disturbed they may
settle on a different attractor point. A
perceptual control system would always act
to return to the same point.

                      Â RM: I think the people who build these

vehicles are just being politically correct
when they talk about “attractor points”. Since
these vehicles are control systems the
reference state of the the variables they
control are not attractor points (like the
resting state of a pendulum or a mass on a
spring); they are the reference states of
controlled variables. The concept of attractor
points is the politically correct way to
refer to controlled (purposefully produced)
results because it implies that these
results can be produced by ordinary
cause-effect processes.Â

           I agree, partially. Controlled results are

attractor points within dynamical systems. But not all
attractor points within dynamical systems are controlled
results. For example, the predator/prey relationship
between penguins and seals may stabilise at a certain
value. It is an attractor point within a dynamical system,
but it is not a controlled result. Add a disturbance with
a bunch of polar bears to the environment and the
relationship between penguins and seals would probably
stabilise at a different value; i.e. a different attractor
point. I think this is what Braitenberg’s vehicles are
like, rather than a perceptual control system, which would
oppose disturbances to return to the same “attractor
point”.

          Regards,

          Rupert

[rsmarken]

[Rick Marken 2018-02-22_14:35:41]

Rupert Young (2018.02.22 16.05)

RM: It's a control system as long as increases in sensory input (heat) above zero cause increases in wheel velocity that move the vehicle away from the cause of the sensory input (the heat source) and decreases in sensory input below zero cause increases in wheel movement that move the vehicle toward the cause of the sensory input. With proper adjustment of gain and slowing this system will be stable and control sensed heat, keeping it at a perceptual level that corresponds to zero perceptual signal.Â

RY: This system would run straight into a heat source (if it were straight ahead), so does that mean it is not a control system?

RM: It would if it would so that. But the system I described would be control control system controlling teh level of heat at it's sensor, maintaining it at a level that corresponds to the zero level of perceptual signal.Â

 RM: I think the people who build these vehicles are just being politically correct when they talk about "attractor points". Since these vehicles are control systems the reference state of the the variables they control are not attractor points (like the resting state of a pendulum or a mass on a spring); they are the reference states of controlled variables. The concept of attractor points is the politically correct way to refer to controlled (purposefully produced) results because it implies that these results can be produced by ordinary cause-effect processes.Â

RY: I agree, partially. Controlled results are attractor points within dynamical systems.

 RM: That's a metaphorical way of putting it.

RY: But not all attractor points within dynamical systems are controlled results.

RM: Right, the one's that aren't are the one's that are not protected from disturbance, such as the position of a mass on a spring or the resting position of a pendulum. Â

RY: For example, the predator/prey relationship between penguins and seals may stabilise at a certain value. It is an attractor point within a dynamical system, but it is not a controlled result. Add a disturbance with a bunch of polar bears to the environment and the relationship between penguins and seals would probably stabilise at a different value; i.e. a different attractor point.

RM: Right. The constant ratio of seals to penguins is an equilibrium point, not the reference state of a controlled variable, because it is not protected from disturbance.Â

RY: I think this is what Braitenberg's vehicles are like, rather than a perceptual control system, which would oppose disturbances to return to the same "attractor point".

RM: Braitenberg vehicles are control systems that do protect the variables they control from disturbance. My little heat control vehicle keeps the heat level at its sensor near zero, protected from disturbances such as moving a heat source closer to or farther from the sensor.Â
Best
Rick
 >

···

On Thu, Feb 22, 2018 at 8:04 AM, Rupert Young <<mailto:rupert@perceptualrobots.com>rupert@perceptualrobots.com> wrote:

Regards,
Rupert

--
Richard S. MarkenÂ
"Perfection is achieved not when you have nothing more to add, but when you
have nothing left to take away.�
                --Antoine de Saint-Exupery

[rupert]

[From Rupert Young (2018.03.17 15.00)]

(Rick Marken 2018-02-22_14:35:41]

Have you ever thought of becoming a politician :) ? I must have

asked three times if you thought Braitenberg vehicles were control
systems, to which you answered yes, though each time the system you
described was not the one I brought up, i.e. not a Braitenberg
vehicle (#1). Perhaps I should assume that you think that
Braitenberg vehicles are not control systems.

Regards,

Rupert

···

Rupert Young (2018.02.22 16.05)

            RY: This system would run straight into a heat

source (if it were straight ahead), so does that mean it
is not a control system?

          RM: It would if it would so that. But the system I

described would be control control system controlling teh
level of heat at it’s sensor, maintaining it at a level
that corresponds to the zero level of perceptual signal.

        ....
          RM: Braitenberg  vehicles are control systems that do

protect the variables they control from disturbance. My
little heat control vehicle keeps the heat level at its
sensor near zero, protected from disturbances such as
moving a heat source closer to or farther from the sensor.

                        RM: It's a control system as long as

increases in sensory input (heat) above zero
cause increases in wheel velocity that move
the vehicle away from the cause of
the sensory input (the heat source) and
decreases in sensory input below zero cause
increases in wheel movement that move the
vehicle toward the cause of the
sensory input. With proper adjustment of
gain and slowing this system will be stable
and control sensed heat, keeping it at a
perceptual level that corresponds to zero
perceptual signal.

[rsmarken]

[Rick Marken 2018-03-18_15:31:52]

[From Rupert Young (2018.03.17 15.00)

RY: Have you ever thought of becoming a politician ?

RM: Well, I was the unanimous choice for president of the senior orchestra in junior high. For two terms! But I decided to quite while I was ahead (doing a job that mainly consisted of just showing up for class;-)

RY: I must have asked three times if you thought Braitenberg vehicles were control systems, to which you answered yes, though each time the system you described was not the one I brought up, i.e. not a Braitenberg vehicle (#1). Perhaps I should assume that you think that Braitenberg vehicles are not control systems.Â

RM: I'm sorry. I don;t remember which vehicle was which or where they were. But the vehicle is a control system if it controls. I think all Braitenberg vehicles control something, like the relative amount of light at two sensors. Maybe you could give me a description of a Braitenberg vehicle that is not a control system and you could see if I agree or not.Â
Best
Rick

···

--
Richard S. MarkenÂ
"Perfection is achieved not when you have nothing more to add, but when you
have nothing left to take away.�
                --Antoine de Saint-Exupery

[rupert]

[From Rupert Young (2018.03.19 10.30)]

(Rick Marken 2018-03-18_15:31:52]

High time for a political comeback then! 2020 to replace the orange
blob? If you knew any ways of ‘controlling people’ it should be a
cinch!
The place to start is vehicle 1 as the conceptualisation of this
permeates the remainder of the vehicles,
It is a one-dimensional system with a single motor and a single
(temperature) sensor. The motor speed is a direct function of the
temperature. So, it goes slowly in cold areas and faster in hotter
areas. What is this controlling, would you say?
Regards,
Rupert

···

[From Rupert Young (2018.03.17 15.00)

RY: Have you ever thought of becoming a politician ?

          RM: Well, I was the unanimous choice for president of

the senior orchestra in junior high. For two terms! But I
decided to quite while I was ahead (doing a job that
mainly consisted of just showing up for class;-)

            RY: I must have

asked three times if you thought Braitenberg vehicles
were control systems, to which you answered yes, though
each time the system you described was not the one I
brought up, i.e. not a Braitenberg vehicle (#1). Perhaps
I should assume that you think that Braitenberg
vehicles are not control systems.

          RM: I'm sorry. I don;t remember which vehicle was which

or where they were. But the vehicle is a control system if
it controls. I think all Braitenberg vehicles control
something, like the relative amount of light at two
sensors. Maybe you could give me a description of a
Braitenberg
vehicle that is not a control system and you could see
if I agree or not.

http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html

[rsmarken]

[Rick Marken 2018-03-19_10:12:19]

[From Rupert Young (2018.03.19 10.30)]

RM: Well, I was the unanimous choice for president of the senior orchestra in junior high. For two terms! But I decided to quite while I was ahead (doing a job that mainly consisted of just showing up for class;-)

RY: High time for a political comeback then! 2020 to replace the orange blob? If you knew any ways of 'controlling people' it should be a cinch!

 RM: I'll think about it;-)

RM: I'm sorry. I don;t remember which vehicle was which or where they were. But the vehicle is a control system if it controls. ..

RY: The place to start is vehicle 1 as the conceptualisation of this permeates the remainder of the vehicles, <Notes On Vehicle 1: Getting Around

RY: It is a one-dimensional system with a single motor and a single (temperature) sensor. The motor speed is a direct function of the temperature. So, it goes slowly in cold areas and faster in hotter areas. What is this controlling, would you say?

RM: This vehicle NOT a control system but it is a closed loop system. It's not a control system because the feedback effect of output on input is positive. So it is an example of what Powers (1978) called a P-system. You could easily turn it into an N-system (a control system) by having motor speed be negatively related to sensed temperature. Then the car would control its distance from heat sources, the distance being proportional to the temperature that produces 0 sensory signal and, hence, no movement toward or away from the heat source.Â
BestÂ
Rick

···

--
Richard S. MarkenÂ
"Perfection is achieved not when you have nothing more to add, but when you
have nothing left to take away.�
                --Antoine de Saint-Exupery

[rupert]

[From Rupert Young (2018.03.25 17.40)]

(Rick Marken 2018-03-19_10:12:19]

Yes, it seems that way. (Is this reference, “Quantitative Analysis
of Purposive Systems etc”?). I’d call it a continuous
stimulus-response system. There is no explicit reference and, hence,
no apparent error to minimise or goal to achieve. I think the effect
of the output on input is sometimes positive and sometimes negative
(if the forward temperature gradient is downwards), it’s entirely
dependent on the environment. Given that this system is the conceptual foundation for all other
Braitenberg’s vehicles it is questionable whether any of them are
control systems. Perhaps, some are, but that is likely to be more by
accident than design. It would be interesting if people could
identify which systems within Braitenberg’s vehicles are controlling
perceptions.
To do that you’d need to sense the temperature gradient wouldn’t
you? Also to control distance it would need to perceive distance
wouldn’t it? Isn’t the only temperature that produces a sensory
signal of 0 a temperature of 0? Did you mean error signal?
Regards,
Rupert

···

                    RM: I'm sorry. I don;t remember which vehicle

was which or where they were. But the vehicle is
a control system if it controls. …

            RY: The place to

start is vehicle 1 as the conceptualisation of this
permeates the remainder of the vehicles,
http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html

            RY: It is a one-dimensional system with a single motor

and a single (temperature) sensor. The motor speed is a
direct function of the temperature. So, it goes slowly
in cold areas and faster in hotter areas. What is this
controlling, would you say?

      RM: This vehicle NOT a control system but it is a closed loop

system. It’s not a control system because the feedback effect
of output on input is positive. So it is an example of what
Powers (1978) called a P-system.

      You could easily turn it into an

N-system (a control system) by having motor speed be
negatively related to sensed temperature. Then the car would
control its distance from heat sources, the distance being
proportional to the temperature that produces 0 sensory signal
and, hence, no movement toward or away from the heat source.

[EetuP]

[Eetu Pikkarainen 2018 03 26]

Powers differentiates three systems: Z is causal stimulus-response system where output does not affect input; P and N are positive and negative feedback systems. Braitenberg 1 is not Z because its output consistently affects its input. Whether it is N or Z
depends on whether the heat source happens to be in front or back of it. If the heat source is in the back side then its output movement decreases its warmth input and it controls the warmth with the zero value where there is so cold that its motor stops.
I would not say say that it controls for distance but onlu for warmth (or rather coldness).

Eetu

Kohteesta: Rupert Young

Lähetetty: sunnuntai 25. maaliskuuta klo 19.39

Aihe: Re: More Lego ev3 demos

Vastaanottaja: csgnet@lists.illinois.edu

[From Rupert Young (2018.03.25 17.40)]

(Rick Marken 2018-03-19_10:12:19]

RM: I’m sorry. I don;t remember which vehicle was which or where they were. But the vehicle is a control system if it controls. …

RY: The place to start is vehicle 1 as the conceptualisation of this permeates the remainder of the vehicles,

http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/Vehicle.1.html

RY: It is a one-dimensional system with a single motor and a single (temperature) sensor. The motor speed is a direct function of the temperature. So, it goes slowly in cold areas and faster in hotter areas. What is this controlling, would you say?

RM: This vehicle NOT a control system but it is a closed loop system. It’s not a control system because the feedback effect of output on input is positive. So it is an example of what Powers (1978) called a P-system.

Yes, it seems that way. (Is this reference, “Quantitative Analysis of Purposive Systems etc”?). I’d call it a continuous stimulus-response system. There is no explicit reference and, hence, no apparent error to minimise or goal to achieve. I think the effect
of the output on input is sometimes positive and sometimes negative (if the forward temperature gradient is downwards), it’s entirely dependent on the environment.

Given that this system is the conceptual foundation for all other Braitenberg’s vehicles it is questionable whether any of them are control systems. Perhaps, some are, but that is likely to be more by accident than design. It would be interesting if people
could identify which systems within Braitenberg’s vehicles are controlling perceptions.

You could easily turn it into an N-system (a control system) by having motor speed be negatively related to sensed temperature. Then the car would control its distance from heat sources, the distance being proportional to the temperature that produces 0 sensory
signal and, hence, no movement toward or away from the heat source.

To do that you’d need to sense the temperature gradient wouldn’t you? Also to control distance it would need to perceive distance wouldn’t it? Isn’t the only temperature that produces a sensory signal of 0 a temperature of 0? Did you mean error signal?

Regards,

Rupert