elektor june 75
M. Keul and H. Lohr
the moth
This is a design for a simple cybernetic model, based on an electric toy car, that will be attracted towards a light source like a moth, negotiating obstacles in its path.
The car has two motors, one to propel it and one for the steering mechanism.
The principle is quite simple. A light-sensitive element is mounted obliquely to the right at the front of the car.
Normally, the steering motor keeps the car on a left turn, but this motor can be reversed by a relay, so that the car turns to the right. This happens each time the light-sensitive elelent receives light.
If the car, travelling to the left, passes a light source, it swerves to the right in the direction of the light. However, it keeps turning to the right, so that after some time the element receives no more light. Then the car will automatically swerve to the left again until the element again receives light from the source, and so on. Thus the car zigzags towards the light source. It behaves more-or-less like a moth, hence the name of this apparatus.
see full pdf here.