This page is about the simple Robots I have built. This started off after seeing an episode of “The X-Files”, where they were bugged, if you’ll excuse the pun, by an infestation of cockroaches. If you’ve seen the episode, you’ll know what I mean.
I discovered a company called millford instruments, who produced a kit of something similar. It was only after I had built it, I saw the episode again, and realised that they had cheated in the X-files, using wheels instead of legs!
Mk I Cockroach
The mark one cockroach uses a small processor called the “Basic Stamp 1”, produced by a company called Parallax, for a ‘brain’. Locomotion is achieved using three model servos connected to the legs in pairs. Two micro switches are used for antennae and two LEDs for flashing eyes.
The cockroach walks in a straight line, until one of its antennae comes into contact with an object. It then takes three steps backwards, and turns away from the object, and then starts walking forward again. Its continues this behavior until it’s batteries run down.
MKI CockroachMk II Cockroach
After building the millford kit I wanted to make the cockroach more aware of it’s surroundings. I was limited by the capacity of it’s ‘brain’, so the mark 2 was created. This one used another device by Parallax, the logically named “BASIC Stamp 2”. This device has twice as many input/output lines and eight times the program memory of the Stamp 1, making it ideal for the mark 2 cockroach. The mark 2 moves in the same way as the mark 1, but in addition to its antennae, it has several other senses.
Two light dependant resistors were used to sense light and shade and a pair of ultra-sonic transducers act as a primitive “sonar”. A microphone is used to detect load noises and a loud-speaker emits a rather pitiful squeak. The behaviour of the mark 2 is slightly different due to its extra senses. It will take two steps forward, use its sonar to detect if anything is moving in front of it. If there is movement it will compare the light levels between its two LDR “eyes” and turn one step towards the darker side. If it hears a loud noise, it will stop and wait for a few seconds before continuing. As a result of it’s extra sensors the mark 2 tends to scuttle around the edges of rooms, trying to stay away from any movement or light.
Visit the Millford Instruments Web Site, for more information on their kits and the Parallax Inc. Web Site, for more information on the BASIC Stamp controllers. The Robot Science and Technology site has some interesting articles and links to other robot related sites.