Robust nonlinear control of a magnetic levitation system via backstepping approach

Proposes a robust nonlinear controller for the position tracking problem of a magnetic levitation system, which is governed by a SISO second-order nonlinear differential equation. The controller is designed in a backstepping manner, based on the nonlinear system model in the presence of parameter uncertainties. The effects of the parameter uncertainties are reduced by a nonlinear damping term and the effects of position error are removed by a PI controller. Input-to-state stability of the control system is analyzed and experimental results are included to show the excellent position tracking performance of the designed control system.