Constraints on Sensitivity Characteristics in Multi-Input Multi-Output Discrete-Time Control Systems

Abstract

This paper is concerned with the limitations on the sensitivity characteristics for discretetime MIMO control systems. By the Poisson inequality for the subharmonic functions, some integral-type constraints and the lower bounds of the weighted H_∞-norm imposed by unstable poles, unstable zeros, and their directions of the open-loop system or the given plant are developed by a factorization approach. These constraints and bounds are also characterized by the state-space forms, which are closely related to a special type of the algebraic Riccati equation.