Identifying a Transfer Function From a Frequency Response

In this paper, the classic Levy identification method is reviewed and reformulated using a complex representation. This new formulation is able to solve the well known bias of the classic method at low frequencies. The formulation is generic, addressing both integer order and fractional order transfer functions. A new algorithm based on a stacked matrix and its pseudo-inverse is proposed to accommodate the data over a wide range of frequencies. Several simulation results are presented, together with a real system identification. This system is the Archimedes Wave Swing, a prototype of a device to convert the energy of sea waves into electricity.Copyright © 2007 by ASME