SYSTEM-IDENTIFICATION USING FREQUENCY SCANNING AND THE EIGENSYSTEM REALIZATION-ALGORITHM

The application of the eigensystem realization algorithm to flexible s tructures excited with nonimpulse type inputs is described. Sinusoidal pulses are a special subset of such inputs, and a discussion is given on their use to lock on to particular modes. The determination of imp ulse response functions from nonimpulse response functions is performe d via a two step procedure. In the first step, free decay data is anal yzed by the eigensystem realization algorithm to determine the structu ral frequencies and damping. Forced response data is analyzed in the s econd step, by solving an overdetermined set of linear equations for t he modal coefficients of the impulse responses. It is shown that the n umber of impulse response coefficients is halved if displacement, velo city, and/or acceleration sensors are used in conjunction with force a ctuators. System identification is completed after the eigensystem rea lization algorithm is used on the impulse responses to produce a linea r state space model of the structure. Numerical examples are given in which structural models are determined from simulated data corrupted w ith noise.