A Continuous Wavelet-based Approach to Identifying Modal Parameters for the AR Model of Helicopters

摘要

The dynamic characteristics of helicopters have been a great consideration in the engineering field.This work presents a wavelet-based approach to determining modal parameters of a helicopter.Continuous wavelet transforms are applied to the dynamic responses of its fuselage.An auto regression (AR) model in the wavelet domain is established from the discrete equations of motion.Modal parameters such as modal frequency,damping ratio and mode shape are then computed from the coefficient matrices of AR models by solving an eigenvalue problem.The effects of wavelet transform scale coefficient and noise on the accuracy to estimate the modal parameters are further investigated.Results comparison are carried out with Least Squares Compiles Exponential estimation method and finite element analysis,to verify that the applied wavelet approach is with high resolution and insensitive to noise,suitable for modal parameters identification of helicopters.