YouTube member AlmightyArjen has published details and a video of an awesome LEGO pneumatic compressor which has been automated using a little Arduino programming and hardware. Watch the demonstration ...

Modify config.ini for your Serial connection. This was primarily developed on linux. Super weird, but the one Windows machine that I tested required a delay after instatiating the Arduino class: ard = ...

This is a basic Arduino code which will allow you to drive the pressure of the pneumatic actuator to a certain value, as well as printing the debug value on the Serial Monitor every 200ms.