H2 Periodic Control on Active Twist Rotor for Vibration Reduction

This paper investigates the application of an active control strategy to reduce vibrations in forward flight through active twist design. The blade twist is actively induced at high frequencies by piezoelectric actuators distributed along the blade span. Macro-fiber composite (MFC) are considered as actuators, allowing a high actuation power with low voltages. The multibody software MBDyn is used to model the isolated rotor of the Bo 105, whose original blades are replaced with blades embedding distributed piezoelectric actuators. The reduction of vibratory loads acting on the hub is obtained through the minimization of appropriate harmonics of the blade root loads, hence working on the rotating reference frame. Due to the periodicity of the system in forward flight, the actuation is governed by a periodic linear H2 controller, designed on an appropriately identified model.