ROBUST-CONTROL OF MAGNETIC-LEVITATION SYSTEMS BY MEANS OF H-INFINITY CONTROL MU-SYNTHESIS

This study is concerned with an application of H(infinity) control and mu synthesis to magnetic levitation sysems which have special flexibl e structures and the solution of the spillover problem. At first, we s how the typical spillover phenomenon caused by the interaction between the control system and the flexible structure system using PID contro l. Next, applying mixed-sensitivity H(infinity) control to the magneti c levitation system, we design the control system for it without spill over and describe in detail how to design an H(infinity) controller. F inally, we analyze the structured singular value and design the mu con troller using D-K iteration. In this paper, we assume the magnetic lev itation system as an uncoupled system between the X and Y directions f or simplicity, which is the third-order system with the exception of t he guideway. As a result, it has been clarified that the H(infinity) c ontroller and mu-controller have the characteristics of two kinds of f ilters, a low-pass filter and a notch filter. It is found that the mu controller is superior to the H(infinity) controller in terms of robus t stability and robust performance. From experiments, we obtained good data on the magnetic levitation without spillover.