Reduced Order Observer Design for Discrete Time Descriptor Systems With Unknown Inputs: An Linear Matrix Inequality Approach

Abstract

Reducedorder observer design methods for both linear and nonlinear discretetime descriptor systems based on the linear matrix inequality (LMI) approach are investigated. We conclude that the conditions under which a fullorder observer exists can also guarantee the existence of a reducedorder observer. By choosing a special reducedorder observer gain matrix, a reducedorder unknown input observer is proposed for linear system with unknown inputs, and then an unknown input reconstruction is provided for some special cases. We also extend above results to the cases of nonlinear systems. Finally, three numerical comparative simulation examples are given to illustrate the effectiveness and merits of proposed methods.