Acrobot swing-up control - Partial Feedback Linearization

Implementation of Mark Spong's swing-up controller for an underactuated double-pendulum.

This is based on Mark Spong's paper: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=407375&tag=1
It implements two swing-up controllers for a double pendulum with only a motor at the second joint (the "elbow"), also called the acrobot. I am not associated with the paper. I've just implemented it in order to play with it. The files include full animation and symbolic derivation scripts. Should be a good learning tool, I hope!

I don't recommend this as a method to control a physical acrobot. The results are very interesting to watch, but with torque-bounded actuators, you're going to have trouble.