The Pneumatic valves are still coming back to "close" position.
Now the air bottle is always "open" to keep the valves "open".

The 30Hz noise is still here. We tried to cut off all the air flows. It only decreased the noise intensity but didn't change its shape.

21/11/2019 :

The pneumatic valves are now connected permanently to the university airflow network.
there is a small air leakage but it is not an issue anymore.

the 30Hz noise has been fixed too as it was coming from the extreme position of M1 and M4 (plan mirrors) and due to mechanical instability in this position (motor "outside")