If you're interested in learning how the legs on micromagic systems robots move so fluidly, you may find the following book a worth while purchase. Its not for the faint hearted, but it should give you all the information you need.
"After searching the web for a couple of days, one book seemed to stand out as a good starting point to learn about IK:- Introduction To Robotics, Mechanics And Control' by John J. Craig. This proved to be a worthy purchase, for it is from this book that I learned all that I have needed, so far, to get my PyE Legs working using IK equations." excerpt from : Matt Denton home page - project PyE