关键词: 控制器降阶, 信息论, 交叉格莱姆矩阵, 最小信息损失, 圈量子引力（LQG）最优控制

Abstract: The issue of designing reduced-order LQG controller is considered from the view of information theory.By exploring the description of the internal state information of the system，two approaches based on cross-Gramian matrix by the principle of minimum information loss are proposed to design LQG reduced-order controller.The performances of the reduced-order LQG closed-loop systems are compared with both the high-order LQG closed-loop and the low-order closed-loop system obtained by the minimum K-L information distance controller reduction method.As the numerical simulation shows the reduced-order closed-loop systems obtained by these two approaches have satisfied performances which prove the efficiency of the controller reduction methods.

Key words: controller reduction, information theory, cross-Gramian, minimum information loss, Loop Quantum Gravity（LQG） optimal control