Low-order H∞ controller design with an application in flexible servomechanisms

This paper considers a design problem involving a servomechanism system with a flexible axis which has a high-order nominal model used for controller design. The controller obtained by a standard H^∞ algorithm is the same order as the generalized plant. This paper investigates low-order H^∞ controller design in the chain-scattering matrix framework. The method uses positive-real matrices to construct a low-order controller generator which is able to generate a set of low-order H^∞ controllers