Figure 1 and VIDEO 1 depict an inverted pendulum driven by a pneumatic air cylinder. The big picture problem is maintaining the pendulum in its upright position. Solving this is important because an "inverted pendulum" is a classical model of control theories--robot arms or humanoid robots are often modeled as multi-link pendulums. This tutorial shows you how to build a pneumatic inverted pendulum and takes approximately a few days to finish.
VIDEO 2: the result of another student reduplicats this project independently by following this tutorial.