Integrated system design by separation

This paper shows, by a numerical example, that there is a certain separation property in the design of mechanical control systems. In particular, we point out that the control bandwidth of a servo-tracking system, achievable by a dynamic output feedback controller with reasonable amount of control effort, is closely related to the frequency range where the open-loop transfer function exhibits positive-realness. A finite frequency positive real property is characterized in terms of linear matrix inequalities. Finally, a systematic procedure for designing a mechanical system having such property is proposed, utilizing powerful convex programming techniques