Frequency-domain weighted RLS model reduction for complex SISO linear system

During the analysis and design of control systems, the complex SISO linear system that consist of several single transfer functions plus different time delay are often encountered and need to be reduced order. However, due to the complicated characteristics, it is difficult for such high-order model to obtain the reduced-order model using the existing methods. In this paper, a frequency-domain weighted recursive least squares (RLS) method is proposed for model reduction of such complex SISO linear system. The involved algorithm is derived, and the computational procedure of the model reduction is presented. At last, numerical examples are offered to verify the effectiveness of the proposed scheme for model reduction.