Abstract
In this paper, we clarify a new relationship between the finite invariant zeros of the generalized plant and the order reduction of the standard H∞ controller. A reducible order is characterized by using the geometric multiplicities of the invariant zeros in the open right half plane. Moreover we show a way to obtain the reduced-order H∞ controller by using the two-Riccati-equation approach. An experiment using a magnetic levitation system as well as numerical examples show that our result is useful.
