A new approach to a sliding mode controller design for a magnetic levitation system

The problem of precisely controlling the position of a ferromagnetic ball above the ground by levitating it against the force of gravity using an electromagnet is of interest because the magnetic levitation system is open loop unstable and highly nonlinear. We have designed a sliding mode controller based on the concept of a proportional integral switching surface for this application. Furthermore, we have compared the proportional integral sliding mode controller and a feedback linearization controller for their performance in controlling the ball position in the presence of parametric and matched uncertainties. Simulation results show that the proportional integral sliding mode controller is more effective than a feedback linearization controller.