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 ‘neurons’.

http://www.rossashby.info

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.

Braitenberg Vehicles

• <http://stevebattle.github.io/braitenberg/vehicle1.html>• <http://stevebattle.github.io/braitenberg/vehicle2.html>

Vehicle 1

Vehicle 2a

Vehicle 2b

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)

Ashby’s Mobile Homeostat

“Suppose U is mobile and is ultrastable, with its critical states set so that it seeks situations of high illumination.”

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”.

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

Systems of variables

left eyeright eye

distanceleft motorright 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 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.”

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

light intensity.

Brightness constancy maintained by scanning

sensor.

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 methodically finds a comfortable position and goes to sleep again.”

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

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.

✔

✘

✔

✔

✔✔

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.

Experimental results?Questions?