motors drive left and right legs to walk and turn, just like a differential drive mobile
third motor moves the head if an obstacle get too near.
motors drive with a gear ratio of 8:24 a gear train that moves
eccentrically the legs,
moving them in circle up forward, down and
This robot has a behaviour modelled with a Finite State Machine,
that makes it resemble a real turtle! Building and programming
instructions are inside my book
"Creating Cool MINDSTORMS NXT Robots".