Servo valve with asymmetrical redundant piezoelectric actuator

A driving stage of a servo valve, the driving stage including a hydraulic unit for ejecting a jet of fluid and a hydraulic unit for receiving the jet of fluid, the hydraulic units being able to be moved relative to each other so as to change their relative position and thereby to generate a pressure differential, one of the two hydraulic units being fixedly mounted on a body of the servo valve and the other hydraulic unit being integral with a mobile unit of the driving stage, movable relative to a body of the servo valve through actuating means, the actuating means comprising a first piezoelectric actuator and a second piezoelectric actuator connected in series, the maximum elongation (Amax41) of the first piezoelectric actuator being substantially equal to half the maximum elongation (Amax42) of the second piezoelectric actuator.