Robinson's Robots



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Note: George Simmons spotted some discrepencies in the spinal cord circuit. I'm in the process of figuring out which part of the diagram is wrong. BNR: 2005-03-20

Hider is a successful attempt to build a robot with complex behaviours using simple BEAM technology. It has no processor, no programing, and no high tech sensor devices. Everything is built from simple components, very basic sensor elements, and simple IC's. The complex behaviours arise in part from the use of 9 sensor elements, illustrating the first law of robotics; "The capability for complex behaviour is limited by the number of sensors." (That's my first law, not Asimov's or Tilden's.)

Hider - watching a wooden column.
Hider looking at a wooden column.

Hider is concerned with survival. Normally it parks itself in bright light where it is easily seen. If the light gets dim, it looks for a brighter place. In the dark it stays still and flashes a beacon every few seconds so it won't get stepped on. And if it hears a loud noise, such as a door slamming or people talking, it "runs away" and looks for a dark place to hide in.

While Hider performs more or less as intended, there have been a few surprises. For example, in the above photo Hider is "looking" at the darkest thing in a sunlit room -- a wooden column. While we might think of a shadow as being darker, Hider doesn't see it that way; it's "eyes" look at the walls, not the floor. In a room with white walls and pale furniture, a nearby column of reddish coloured wood looks very dark.

Hider - side view.
Side view of Hider, showing the HDPE wheel extensions.

In the view above Hider is tilted quite sharply. On carpet the wheels sink in slightly and the body is almost level. You can clearly see the feelers (made from #18 music wire). These were made from a single piece of wire carefully shaped and inserted through holes drilled through the sides of two momentary-contact push buttons. The wire distorts just enough so only the switch closest to an obstacle is depressed. Also visible just behind the wire is the yellow-coloured IR LED used in the edge detector. Directly behind the LED, on the opposite side of the circuit board, is the dark blue (black in the photo) IR photodector which senses pulses reflected off the floor. If an edge is encountered, the PD stops receiving pulses and the robot backs away from the edge.

The following pages describe Hider's structure and circuits. If you want to build your own version of Hider you can use this information as presented, or you devise your own control circuits. The pages are presented in the order I built the robot.

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If you want to take a side trip to see more images or some specifications, you can click here. There's about 400 k of images to load.

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Copyright © 2001 - 2005 Bruce N. Robinson. Last updated 2005-03-20.