Rotor/active magnetic bearing transient control using wavelet predictive moderation

A novel method for predicting the ultimate steady-state vibration amplitudes from measured transient responses in multi-input, multi-output flexible rotor/magnetic bearing systems is presented. The technique is based around a multi-level wavelet coefficient analysis with in-built transient system dynamics. The relation between an input disturbance wavelet coefficient acting on the system and a measured vibration wavelet coefficient is identified theoretically for non-identical wavelets. A controller is formulated in the wavelet coefficient domain with control forces derived from proportional feedback of displacement wavelet coefficients. Improved transient performance is achieved using wavelet coefficient steady-state prediction to moderate the control signal. Experimental validation of the controller using mass-loss tests demonstrates the manner in which transient vibration attenuation may be achieved.