Periodic Output Feedback Control for Helicopter Vibration Reduction

This paper investigates the potentiality of the periodic direct output feedback (POF) control to reduce rotor vibrations in forward flight. The blade control strategy relies on their active twist actuation. The blades are twisted by means of macro-fiber composite (MFC) piezoelectric actuators distributed along the span. The multibody software MBDyn is used to model the isolated rotor of the Bo105, with the original blades replaced by actively controlled ones. The periodic output feedback controller reduces the hub loads by minimizing selected harmonics of the blade root shear force. The results are compared with those obtained with a periodic H2 optimal controller. All the closed loop analysis are performed by simulating the rotor dynamics with MBDyn while running the control code in Simulink. A specialized communication library is used to coordinate the co-simulation and exchange data between the two codes.