Mixed Sensitivity Design of Magnetic Suspension System

When the mixed sensitivity method is applied to the system design, the model of the augmented plant is often not satisfied with the standard H∞ control problem. Because of the rank \( D_{12} \) assumption, the design problem cannot be solved. In order to solve this problem, the augmented model of the system is established, and the selection of a decimal number is analyzed. The principle of selecting decimals in full rank \( D_{12} \) design is given, and the simulation of magnetic suspension system is carried out, which shows that the wrong design results can be easily obtained if the decimals are not properly chosen. This paper also points out that the Bode integral constraint should be taken into account in the design, based on which the weight function can be selected reasonably to achieve a better performance. The analysis method given in this paper is generally applicable to controlled plants whose direct transfer coefficient matrix is equal to zero.