This looks like the beginnings of a nice NXT based delta robot.
This fine delta robot was built by Viacheslav Slavinsky. He has extensive information about the robot here, including some of the math for the kinematics. Thought he doesn't provide the full differential equations of motion, a simplified model is probably sufficient to get started.
While this isn't a delta robot, it is a parallel manipulator and awesome. The increased workspace is a nice touch.
This one reminds me of marionettes.
Maybe I'll have some delta robot packed biscotti for breakfast.