Robust Nonlinear Control of a Feedback Linearizable Voltage-Controlled Magnetic Levitation System

This paper considers the position tracking problem of a voltage-controlled magnetic levitation system. It is well known that the control problem is quite complicated and challenging due to inherent nonlinearities associated with the electromechanical dynamics. And feedback linearization approach via coordinate transformation is considered to be a useful candidate to tackle the control problem. Usually however, feedback linearization control does not guarantee exact linearization and robustness in the presence of model uncertainties. In this paper, we propose a robust nonlinear controller in the presence of parametric uncertainties. The design procedure is carried out in a backstepping design manner, by employing nonlinear damping terms to suppress the effects of parametric uncertainties which may cause instability. Input-to-state stable property of the control system is analyzed, and experimental results are included to show the excellent position tracking performance of the designed control system.