Abstract
A stable magnetic levitation system can levitate objects under system uncertainties and external disturbance through magnetic force without direct contact, it can avoid abrasion, noise and energy loss due to friction. To control a maglev system, however, encounters two crucial problems inevitably, i.e. nonlinearity and dynamic coupling. This thesis presents a control law combining Sliding Mode Control (SMC) and Mode Switching Control (MSC) to ease the adverse effect of these two problems and achieve precision positioning. The controlled system utilized a sliding-mode control scheme which is then switched to a sliding-mode controller with integral term added to the sliding variable while entering the vicinity of an operating point. This thesis also proposes a procedure to determine parameters and coefficients of the controller according to different operating characteristics. A pc-based controlled system has been deviced to perform different tasks for verification and performance evaluation. Experimental results on an actual maglev system have further validated its feasibility and practicability.