MODEL-REDUCTION OF SISO SYSTEMS BY ROUTH EXPANSION AND BALANCING METHOD

Among various model reduction methods for single-input single-output (SISO) systems, the balancing method has recently received much attention due to its many attractive properties. However, it is often criticized that the method fails to give a reduced-order model without having steady-state response error for a step input. To remedy this drawback, we propose in this paper. a new reduction procedure. It utilizes the Routh canonical expansion to decompose the full SISO system, and then applies the balancing method to reduce the order of a decomposed subsystem. A reduced-older model is then synthesized from the first Routh expansion coefficients and the reduced-order subsystem. The reduced-order model obtained shares good properties that are inherent to the Routh approximation method and the balancing truncation method.