A multivariate maximum likelihood method for modal parameter estimation

A multivariate maximum likelihood procedure for the estimation of modal parameters is presented. The vibrating system is excited by a random force and sensors output only are used to estimate the natural frequencies and damping coefficients of the system. The method works on time domain and a vector autoregressive moving average (VARMA) process is used. The information about modal parameters is contained in the multivariate autoregressive part, which is estimated using an iterative maximum likelihood algorithm. This algorithm uses a score technique and output data only. A numerical example and an experimental result based on three beams show the efficiency of this maximum likelihood approach for modal parameter estimation.