Comparison of suboptimal control methods in magnetic levitation system

The use of active magnetic bearings (AMB) is increasing in high-speed applications, because their low friction operation allows higher rotational speeds than the traditional bearings. The inherent instability and complexity of the AMB rotor system with high nonlinearities pose challenges to the controller design. This leads to a problem of robust design. Robustness of LQG and loop-shaping H_∞ controllers is compared with the help of the evolutionary algorithm both theoretically and based on experimental measurements.