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Imperial-Drone The-Nevik by David Buckley
November 1997

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    A friend wanted to learn about robots so while he was learning how to solder I made two Imperial-Drone robots, The-Nevik and The-Gotan so he could then learn how to program before building and programing a robot himself for his school project. The two robots were identical apart from The-Gotan having green bump sensors instead of red. I kept The-Nevik while Edward kept The-Gotan.

    Each was powered by a single 9v battery and was controlled by a Stamp1 from Parallax Inc see Links page. Two motors from cassette players drive the two wheels through simple friction drives, the motor shafts bear directly on the tyres. This eliminated gearing but I had to hunt round toy shops for suitable rubber tyres which were both smooth and round.

    The Stamp1 has only eight I/O pins and the motor controller uses four of them and since I wanted the robots to be responsive to light, which used two more pins, it only left two for the bump sensors. As can be seen from the photos there are six microswitches, two have the feelers mounted on them and the other four have the bump plates mounted. The three switches on each side are simply wired in parallel since the action required if a feeler or a bumper hits is the same - generally back up a little and turn away before continuing.

    The motor controller used is an L293E which doesn't have internal diodes to suppress the inductive transient motor currents. I forgot about this hence the diodes soldered across the L293E chip on the motherboard by the switches.

    The switch at the rear is the main On/Off switch while the one at the side is the On/Off switch for the motors. Underneath is a charging socket for if a rechargeable 9v battery is used. Just before I built these robots I had made a Stamp development board and standardised on a 12-way connector for all my Stamp add-on boards. Two of these are at the front of the mother board and a Stamp brain is plugged into one and a board with a buffered set of eight LEDs plugged into the other. The photo above shows version two of the Stamp Brain.