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Ashby’s Mobile
Homeostat
Steve Battle

@stevebattle www.stevebattle.me
Experiment:
http://stevebattle.github.io/homeostat/
W. Ross Ashby’s Homeostat
• four surplus RAF bomb
control switch-gear
kits, refashioned into
electro-mechanical
artificial...
Not just stable but
ultra-stable
• homeostasis: As a queen bee
lays her eggs, bees maintain a
stable cluster temperature a...
Braitenberg Vehicles
• <http://stevebattle.github.io/braitenberg/vehicle1.html>
• <http://stevebattle.github.io/braitenber...
Simulated Environment
•The homeostat represented both brain & anti-brain.
•This changes with the mobile homeostat.
Velocit...
Ashby’s Mobile Homeostat
“Suppose U is mobile
and is ultrastable,
with its critical
states set so that it
seeks situations...
Experiment

http://stevebattle.github.io/homeostat/
• “Marina severed the attachments of the ..
muscles of a monkey’s eyeb...
Sensory Inversion
1. Manual
deflection
on unit 2
2. Positive
response
from unit 1
3. Reverse
polarity from
unit 1 to 2
4. U...
Systems of variables
left eye
right eye
distance
left motor
right motor
unit 1
unit 2
manual parameter
reduced connectivity
The Law of 

Requisite Variety
“An organism should be as intelligent as its
environment - no more no less.”
• If we add mo...
Does it learn?
Cybernetics

Transactions of the Ninth Conference
Josiah Macy Foundation, 1952.
U Robot
“Suppose U is mobile and is ultrastable.”
Eyes mounted 90° apart.
Forward and rear facing
sensors return cosine of...
Connections between even a
small number of brain cells can
produce complex behaviours.
William Grey Walter, Bristol 1948
ELSIE: Electro-mechanical robot,
Light Sensitive with Internal
and External stability.
Machina Speculatrix
Machina sopora
• Walter likened the
homeostat to a “fireside
cat or dog which only
stirs when disturbed,
and then methodic...
The dimensions of autonomy*
A. The extent to which response to the
environment is direct or indirect.

B. The extent to wh...
M.speculatrix is not
just reactive, it has
internal state
M.sopora is not just
reactive but has
internal feedback loops
M....
A shortcoming
• “Further variables are
put between the
environment and the
essential variables
(the relay). The relay
thus...
Experimental results?
Questions?
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Ashby's Mobile homeostat

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In Design for a Brain, W. Ross Ashby speculates about the possibility of creating a mobile homeostat "with its critical states set so that it seeks situations of high illumination." This talk explores an embedding of Ashby's homeostat within a simulated robot and environment, exploring the question as to whether the classic homeostat architecture is able to adapt to this environment. Remaining faithful to the physical design of Ashby's device, this simulation enables us to quantitatively evaluate Ashby's proposition that homeostasis can be achieved through ultrastability.

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Ashby's Mobile homeostat

  1. 1. Ashby’s Mobile Homeostat Steve Battle
 @stevebattle www.stevebattle.me Experiment: http://stevebattle.github.io/homeostat/
  2. 2. W. Ross Ashby’s Homeostat • four surplus RAF bomb control switch-gear kits, refashioned into electro-mechanical artificial ‘neurons’. http://www.rossashby.info
  3. 3. Not just stable but ultra-stable • homeostasis: As a queen bee lays her eggs, bees maintain a stable cluster temperature at around 20ºC. Bees on the outside of the cluster form an insulating shell while those on the inside can generate heat by contracting their thoracic muscles. • Maintaining temperature is essential to bee survival. • Ultrastability is about maintaining essential variables within limits.
  4. 4. Braitenberg Vehicles • <http://stevebattle.github.io/braitenberg/vehicle1.html> • <http://stevebattle.github.io/braitenberg/vehicle2.html> Vehicle 1 Vehicle 2a Vehicle 2b
  5. 5. Simulated Environment •The homeostat represented both brain & anti-brain. •This changes with the mobile homeostat. Velocity is average of the 2 wheels • 2D kinematic model based on the Rossum Project
 <http://rossum.sourceforge.net/papers/DiffSteer/> Proportional to the difference between the 2 wheels Cosine of the angle to the light source (brightness constancy)
  6. 6. Ashby’s Mobile Homeostat “Suppose U is mobile and is ultrastable, with its critical states set so that it seeks situations of high illumination.”
  7. 7. Experiment
 http://stevebattle.github.io/homeostat/ • “Marina severed the attachments of the .. muscles of a monkey’s eyeball and re- attached them in a crossed position” • “Sperry severed the nerves supplying the .. muscles in the arm of a spider monkey, and rejoined them in a crossed position” • See Di Paolo, “Homeostatic adaptation to inversion of the visual field and other sensorimotor disruptions”.
  8. 8. Sensory Inversion 1. Manual deflection on unit 2 2. Positive response from unit 1 3. Reverse polarity from unit 1 to 2 4. Unit 1 goes out of bounds 5. Unit 1 restabilizes 6. Manual deflection on unit 2 7. Negative response from unit 1
  9. 9. Systems of variables left eye right eye distance left motor right motor unit 1 unit 2 manual parameter reduced connectivity
  10. 10. The Law of 
 Requisite Variety “An organism should be as intelligent as its environment - no more no less.” • If we add more units than are necessary, the time taken to reach stability increases. • If we reduce connectivity (while maintaining functionality) the time taken is reduced. “coordination can take place through the environment; communication within the nervous system is not always necessary.”
  11. 11. Does it learn? Cybernetics
 Transactions of the Ninth Conference Josiah Macy Foundation, 1952.
  12. 12. U Robot “Suppose U is mobile and is ultrastable.” Eyes mounted 90° apart. Forward and rear facing sensors return cosine of light intensity. Brightness constancy maintained by scanning sensor.
  13. 13. Connections between even a small number of brain cells can produce complex behaviours. William Grey Walter, Bristol 1948
  14. 14. ELSIE: Electro-mechanical robot, Light Sensitive with Internal and External stability. Machina Speculatrix
  15. 15. Machina sopora • Walter likened the homeostat to a “fireside cat or dog which only stirs when disturbed, and then methodically finds a comfortable position and goes to sleep again.”
  16. 16. The dimensions of autonomy* A. The extent to which response to the environment is direct or indirect.
 B. The extent to which the controlling mechanisms were self-generated rather than externally imposed.
 C.The extent to which inner directing mechanisms can be reflected upon, and/or selectively modified. Autonomy is the greater, the more behaviour is directed by self-generated (and idiosyncratic) inner mechanisms, nicely responsive to the specific problem-situation, yet reflexively modifiable by wider concerns. *Boden, Autonomy and Artificiality
  17. 17. M.speculatrix is not just reactive, it has internal state M.sopora is not just reactive but has internal feedback loops M.spec's mechanisms were hand-crafted by Grey Walter M.sopora’s internal connectivity is randomly self-generated M.spec is adapted for survival, anticipating threats to its essential variables M.sopora is highly adaptive to change being ultrastable A. B. C. ✔ ✘ ✔ ✔ ✔✔
  18. 18. A shortcoming • “Further variables are put between the environment and the essential variables (the relay). The relay thus never 'sees' the environment directly.” • “This picture must be used if any severe test of a reacting system (artificial brain) is to be applied.” • This is like growing a shell rather than using intelligence.
  19. 19. Experimental results? Questions?

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