This controller is designed to be moved with the left hand of the musician. Five potentiometers with a rudimental "self return" mechanism are wired to the fingers, outputting the position as voltage. Arduino outputs the raw values of the potentiometer, and in addition the mean of the sensors and the radius and angle of the barycentrum of the shape with respect to the center. Below you can see a picture of the whole system and the quoted design of the mechanism.
Picture about Gesture Controller.
Quoted design of a self return mechanism for potentiometer.