Identification of rational approximate models in H-infinity using generalized orthonormal basis

Robust identification with FIR models fails to be successful when the numbe r of coefficients to be estimated becomes large, caused by Lightly damped m odes of the plant or poles very close to the unit circle. The paper present s a two-stage algorithm to obtain a low-order approximate model in frequenc y domain in a generalized orthonormal basis with guaranteed H-infinity erro r bound for deterministic linear time-invariant stable systems, the first s tage being an L-infinity rational approximation and the second nonlinear st ep being an H-infinity rational approximation.