Abstract: Strict dynamic operating accuracy is the prerequisite of the realization of the function of a precision rotor, which demands much higher vibration measurement precision than that for traditional industry rotors. Although the accurate extraction of vibration parameters, such as amplitude, frequency and phase, has been realized with several modified FFT methods, the initial phase zero shift error and its reduction method still require further investigation. An in-depth study on the source and the change rule of this error is made and an error reduction method suitable for precision measurement is presented. The theory and the implementation of this method are discussed. The effectiveness and feasibility of this method has been testified by the result of a simulation experiment and a real test, respectively. The analytical conclusion shows that this method provides a reliable solution scheme to improve the phase measurement precision.

Key words: Initial phase, Precision measurement, Vibration, Zero shift error