The application of energy operator demodulation approach based on EMD in mechanical system identification

The dynamic properties, such as the natural frequencies and damping ratios, of ultra-precise positioning systems are needed for accurately predicting the response to external excitations and achieving high precision. This paper proposes the energy operator demodulation approach based on the empirical mode decomposition (EMD) method for realizing parametric identification, which has high identification precision and low calculation. Firstly, the EMD method is used to decompose measured impulse response of a MDOF structure into a number of modal responses. Then the energy operator demodulation approach is applied to each modal response to calculate the instantaneous amplitudes and instantaneous frequencies. Finally, the linear least-square fit procedure is performed to accurately estimate the system parameters, such as the natural frequencies and damping ratios. The theoretical analysis and simulation results demonstrate that the energy operator demodulation approach based on EMD can be successfully applied to system identification.