Abstract: Focusing on the problems of time-varying structure modal parameter estimation for a launch vehicle, a novel time-varying structure modal parameter estimation method in deterministic evolution based on the time-varying auto- regressive moving average (TARMA) model is proposed. The method takes the advantage of a wavelet function in detail representation and uses it as the basis function of time-varying parameters in the TARMA model, and the wavelet basis based FS-TARMA model is finally established. In order to estimate the time-varying parameters in a linear manner, the two-step least square estimation method is proposed. The proposed method is verified by the core stage of Ariane V time-varying finite element model with its counterpart Fourier basis FS-TARMA method, and the comparative identification results demonstrate that the superior achievable accuracy and enhanced tracking capabilities of the Mexican wavelet basis FS-TARMA method.

Key words: Launch vehicle, Time-varying structure, Dynamic modeling, Modal parameter estimation, Wavelet function