Nonlinear robust control of a levitation system with hybrid electromagnets

In this study; we present a model based robust controller for a one degree-of-freedom magnetic levitation system with hybrid electromagnets. Nonlinear equations of the magnetic force model have been used to develop the model based controller. The proposed controller can handle parametric uncertainties and only requires air gap and coil current measurements. The output of the controller is the voltage input of the coils and back-stepping procedure have been applied to reach the voltage dynamics over current dynamics. The stability and convergence of the closed loop system have been proved via Lyapunov-type arguments. Simulation results are presented to illustrate the performance of the proposed robust controller.