A two-step procedure for estimation of instantaneous rotational speed with large fluctuations

This paper addresses the issue of estimating the machine rotational speed based on vibration signal measurement. Advantages and limitations of existing methods are presented. Most of these methods give insufficient results when dealing either with significant variations of the rotational speed or with signals of relatively complex spectral characteristic. In order to overcome these obstacles, a new two-step method for instantaneous frequency estimation is proposed. The described method is based on principles of phase demodulation and joint time-frequency analysis, taking advantage of both of them. The paper presents the method and the algorithm for its implementation on the example of a simulated vibration signal. Finally, test rig experiment vibration data is used to test the efficiency of the method.