W. Grey Walter: The Machina speculatrix

Renato M.E. Sabbatini, PhD

A snapshot of "Machina speculatrix", taken by Walter,
as it enter its "hutch", where it can be "fed" with energy.
The light inside the shelter attracted the tortoise to
its interior, as the battery weakened,
making it overcome the phototropism.

Original drawing of the electronic control (with vacuum tubes)
of one of W. Grey Walter's tortoises. It's an extremely simple
circuit, but that was able to generate complex and impredictable behavior as its sensors interacted with the environment.

Elsie's original photo, with its components identified.
The robot nicknamed "tortoise", due to its appearance
had three wheels, each one with an independent motor.
Power was supplied by a DC battery.
(right side, at the back of the system).

Light path generated by Elsie as it speculatively
approached the lit "hutch". Walter got these pictures
by means of a candle glued over the robot's shell
and overexposing the film.

The "dance" of two turtles, each with a light sensor and a
light source over its shell, produces a strange movement,
that reminds the mating behavior of animals,
fascinated Walter and his readers

Next: W. Grey Walter: A Short Biography