| Abstract: | In forward flight, the helicopter performance is seriously affected by the airframe vibration caused by asymmetrical airflow through the rotor disk. so the higher harmonic rotor blade pitch control technique is becoming an active subject in the 1980's, which is one of the active control techniques of helicopter vibration reduction and whose effectivity has been demonstrated by flight testing. In the view of control theory, this paper interprets the basic principles of higher harmonic control(HHC) and proposes mathematical models of the rotor and of airframe vibration, as well as methods for identification of the parameters. A higher harmonic controller is designed and the results of numerical simulation show that the vibration level is reduced effectively. |
