Design and control of a passive magnetic levitation carrier system

A passive magnetic levitation (maglev) carrier is a transportation device that is based on magnetic levitation and does not have any electric circuits on the moving part. Because the actuation devices are not in the moving platform for passive operation, the levitation forces are non-homogenous. This characteristic makes the design and control of the system challenging. We present design and control procedures for a passive maglev carrier system. To achieve stable and accurate levitation, mechanical analyses were performed to determine the configuration and locations of the levitation magnets. The key challenge in the control design is that the locations and magnitudes of the levitation forces are not continuous around the edge of the moving platform when it passes the magnet. Therefore, the longitudinal positions of the magnets relative to the moving platform are a noise (uncontrollable) factor for the controller. The control parameters should be robust against the noise factor to achieve reliable performance. The Taguchi method was used to determine the optimal control parameters in the presence of the noise factor. The optimized gain reduced the position variation of the levitated carrier by 50% in terms of the root mean square error.