Synthesis of positive real multivariable feedback systems

This is a tutorial paper describing the application of infinity-norm optimal control theory to the synthesis of sector bounded and positive-real multivariable feedback systems. The paper gives a concise treatment of the practical aspects of the theory, describing how it has been implemented via state-space-oriented computer algorithms. Included is a concise summary of the state-space approach to infinity norm control developed by Doyle and by Safonov and Verma, based on the Hankel model reduction theory and incorporating the multivariable Hankel results of Glover.