Stable Routh-Padé-type approximation in model reduction of interval systems

An interval Padé-type approximation is introduced and then Routh-Padé-type method (IRPTM) is presented to model reduction in interval systems. The denominator in reduced model is obtained from the stable Routh table, and its numerator is constructed by the interval Padé-type definition. Compared to the existing Routh-Padé method, IRPTM does not need to solve linear interval equations. Hence, we do not have to compute interval division in the process. Moreover, theoretical analysis shows that IRPTM has smaller computational cost than that of Routh-Padé method. A typical numerical example is given to illustrate our method.