Simultaneous Reduction of Helicopter Rotor Hub Vibratory Loads and Fuselage Vibration using the Higher Harmonic Control Technique

A numerical study was performed on the simultaneous reduction of helicopter rotor hub vibratory loads and fuselage vibrations using the higher harmonic control (HHC) technique. A CAMRAD II model for a medium utility helicopter was constructed for aeromechanical analysis. A linear system model incorporating vibratory hub loads and fuselage vibration characteristics was identified offline; subsequently, an optimal control input for vibration reduction was calculated. By adjusting the weights in the objective function, we implemented and compared three cases. When using weights that consider both hub vibratory loads and fuselage vibrations, the simultaneous vibration reduction was achieved. We also confirmed that when the calculated optimal control inputs were applied to the CAMRAD II model, the expected vibration reduction performance was achieved.