A Vibration-Rejection Control for a Magnetic Suspension System

This paper presents a vibration-rejection control design for a magnetic suspension system which has strong non-linearity, open-loop unstable characteristics, high-order flexible modes, and parameter variations. The target plant to be controlled consists of a U-core electromagnet and a flexible rail. We describe the test rig and formulate the mathematical model and then we set up a control problem as the mixed sensitivity problem where the augmented plant is constructed with frequency weighting functions and the feedback controller is designed by using the H$\infty$ controller. The effectiveness of the designed controller for the magnetic suspension system with high-order flexible modes is validated and justified using several simulations. These results show that the magnetic suspension system is robustly stable against disturbance and gives the well-damped tracking performance ...