Usually servo motors are limited in the circular motion in which they can twist. In the video below, Vincent Groenhuis demonstrates that with some fabrication added to the servos (like 3D printed parts) one can make a servo-controlled pneumatic valve.

The servo valve allows to control pneumatic devices using standard or micro RC servos, making it a very cost-effective solution for controlling pneumatic projects.

The valve body is the same as in the manual valve, so the connections are compatible with the manifold base, connectors/valves and logic gates.

After assembling the servo valve(s) these can be controlled using suitable servo controller hardware and software. There is one important peculiarity in controlling this type of servo valve: the setpoint is often not reached due to friction between the valve and switch (undershoot). If not accounted for, this would keep the motor powered and cause high current consumption, a buzzing noise and stress on the servo teeth. A good solution is to initially add 2° to the setpoint and revert to the original setpoint after 350 ms.

The motors are controlled using an Adafruit Motor Shield. There is an Arduino library for programming motors and other devices using these valves.

See the video below and the modeling on Thingiverse. Also see Vincent’s blog on his designs.