Robots come in many shapes and sizes, and one could argue that those which move around on legs are the most interesting. Six legs or more is relatively easy as your bot can maintain three points of contact while the others move around; once you get to four or fewer points of contact, things get a bit more complicated. Oracid1, however, has developed his own series of linkage-based quadrupeds, using an interesting LEGO linkage system and an Arduino for control.
The robot shown in the video below shuffles around on four legs, guided by a trio of ultrasonic sensors that help it avoid obstacles. It does an admirable job until around 6:45 where it gets skewered on a chair leg that sticks out in a bit of a precarious position, but what is interesting here is the way that the legs move. Instead of shoulder and elbow-type joints, everything is handled by linkages in the shoulder which house four SG90micro servos. Two pairs of servos are employed to actuate a front and back section of each leg, which are linked together with a system of joints for excellent positional control in a single plane. Having two servos positioned back-to-back is also a notable technique, allowing for enhanced torque and better symmetry.
Arduino Code is available on GitHub if you’d like to examine how the autonomous vehicle is controlled.
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Author: Jeremy S. Cook