H_∞ control design for unstable plants  

作　　者：何朕 孟范伟 周荻 王广雄 

机构地区：[1]Dept. of Control Science and Engineering,Harbin Institute of Technology

出　　处：《Journal of Harbin Institute of Technology(New Series)》2010年第3期401-404,共4页哈尔滨工业大学学报（英文版）

基　　金：Sponsored by the National Natural Science Foundation of China (Grant No.60674102)

摘　　要：For the control of unstable plants,it is required that the Nyquist locus of the system should encircle anticlockwise the point-1+j0,and the performance weighting function must be selected based on the specific requirement of the mid-frequency gain. Besides,the performance limitation imposed by the Bode's integral also must be considered. Therefore the H∞ design for unstable plants is different from that in the regular case. It is pointed out that the sensitivity function for unstable plants must remain constant over the mid-frequency range to ensure a robust design. The selection of weighting functions to meet these requirements in the H∞ design is discussed in detail in the paper. A mixed sensitivity H∞ design example is also given to demonstrate the special considerations of the design.For the control of unstable plants, it is required that the Nyquist locus of the system should encircle anticlockwise the point - 1 ＋ j0, and the performance weighting function must be selected based on the specific requirement of the mid-frequency gain. Besides, the performance limitation imposed by the Bode＇s integral also must be considered. Therefore the H∞ design for unstable plants is different from that in the regular case. It is pointed out that the sensitivity function for unstable plants must remain constant over the mid-frequency range to ensure a robust design. The selection of weighting functions to meet these requirements in the H, design is discussed in detail in the paper. A mixed sensitivity H∞ design example is also given to demonstrate the special considerations of the design.

关 键 词：unstable plant H∞ design mixed sensitivity electromagnetic levitation 

分 类 号：TP273[自动化与计算机技术—检测技术与自动化装置]