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My Tetrabot


Four-legged of course.The first 'bot I built. Powered by "El cheapo" servos, one per leg. In the beginning I used a Basic Stamp I to control the servos but after a short PIC intermezzo I took to AVR's ( AT90S2313, in fact ). The programming is done using the Bascom Basic Compiler by Mark Alberts and MCSELEC. There is a really generous trial version available at the MCSELEC site. There are even some servo specific instructions, making the driving of a servo real easy.
I am writing more and more code in 'C', though.


This 'bot has the first beginnings of "interaction": it "reacts" on crashing into something ;). This really elaborate behaviour is done by two Cherry type switches under the front bumper. Hitting something with just one end of the bumper will make the 'bot back up and turn it's rear to the same side, thus trying to evade the obstacle. After a few moments it starts going forward again. Hitting an obstacle with both switches simultaneously (yes, it does happen!) will make it go backwards straight. And keep on bouncing forever :)


The design of the legs was a bit of a problem :) . I used a plastic rod with an L-profile: light but stiff enough. But there was not enough traction. So I needed feet as well. In the beginning I used a green rubber eraser (take a close look at the first picture). Then I read about using PVC tubes for that purpose. That actually works well and makes for nice green feet, too. The antennae are a tribute to my kids :)


As mentioned elsewhere this 'bot doesn't walk, it sort of "hops" or "gallops". I don't care ;). Steering it will be a heck of a task yet ... There's no "behaviour" so far. No use really, as long as I can't steer it :) ...

[GIF of the trike]

An "animated GIF" (1.4Mb) showing the Tetrabot "in action". Sorry about the poor quality.