Dual PIO-Based Controller Design for Robustness Improvement of a Magnetic Levitation System

Magnetic levitation systems have a high potential in industrial applications. However, their nonlinear and open-loop unstable nature combined with susceptibility to system parameter uncertainties and external disturbances poses a challenging control problem. As a result, most control techniques applied to these systems are advanced but complex. This paper proposes a proportional–integral observer (PIO)-based control scheme still using a simple conventional cascade controller to enhance robustness. Design of the controller is presented along with computer simulations to verify that the controller is capable of maintaining nominal performance even under such severe conditions. In addition, the performance of the observer’s compensatory action is analyzed according to the singular perturbation theory.