Robotics Reference
In-Depth Information
Figure 10.
William Grey Walter soldering one of his tortoise robots (circa 1948) from
The Robot topic
by Richard Pawson (Windward, U.K., 1985, page 14)
third was for steering. The tortoise's “sense organs” were extremely sim-
ple, consisting only of a photo-electric cell
2
to give it sensitivity to light
and some electrical contacts mounted on the tortoise's surface and serv-
ing as touch sensors, which enabled the creature to respond to anything
with which one of its sensors came into contact. A telephone battery
provided the tortoise's power and a plastic shell covered the whole assem-
bly and provided a measure of protection against physical damage to the
tortoise's innards.
The tortoise's “nervous system” was also rather primitive. An elec-
tronic circuit incorporating two vacuum tubes
3
controlled the wheel
motors and the tortoise's sense of direction, using information about its
surroundings that had been acquired by the sensors. The tortoise could
perform only two actions: it could avoid big obstacles, which it detected
by a contact sensor, retreating when it hit one; and it was attracted to
sources of light that were detected by its photo-electric cell, though if the
light was too intense the robot backed off rather than moving towards the
light. Until it saw a light, the photo-electric cell was constantly rotating,
scanning its horizon for light signals.
2
A photo-electric cell is a device for converting light into electrical energy.
3
Vacuum tubes (called valves in the U.K.) were glass tubes containing complicated-looking
arrangements of electronic components in the form of metallic plates. They were employed in
amplifiers, radios and other electronic products before the introduction of transistors.
