Application of ILQ-based frequency-shaping control to a magnetic levitation system

We deal with a magnetic levitation system with a Y shape iron plate as a levitated vehicle. The control problem is to suppress a spillover due to unmodeled dynamics. This problem has been solved by a high order H/sub /spl infin// controller. Here, we solve it by designing an observer-based stabilizing controller based on ILQ servo design method. The design is carried out by specifying two frequency responses for tracking and noise suppression asymptotically as the gain tuning parameters tend to infinity. As a result, a lower order controller suppressing the spillover is obtained and its efficiency is confirmed by experiment.