$z$ -Domain Orthonormal Basis Functions for Physical System Identifications

In this paper, novel z-domain orthonormal basis functions are presented for physical systems identification. The new basis functions yield guaranteed real-valued time-domain responses for physical systems containing both real and complex-conjugate poles. Also, application of the new basis functions is demonstrated by adopting them for z-domain orthogonal vector fitting algorithm. Necessary theoretical foundations and validating examples are presented.