Nonlinear Robust Control of a Magnetic Levitation System

This paper deals with the design of a nonlinear robust control scheme for a magnetic levitation system. We define a new switching function to form a variable structure feedback control in order to help improve tracking performance of the system. We practically implemented the controller in an experimental magnetic levitation system and investigated its tracking performance. Because not all state variables of the system can be measured, we used an alphabeta; filter to estimate the unknown state variables. The experimental results on the controlled magnetic levitation system indicate the newly developed control scheme is effective in face of the highly nonlinearities and uncertainties of the magnetic system