Robust output feedback control of a magnetic levitation system via high-gain observer

This paper proposes a novel robust output feedback controller for an electromechanical system in the presence of external disturbance and uncertainties of physical parameters. By exploiting the cascade features of backstepping design, a simple disturbance observer is proposed to suppress the effects of the uncertainties, and a high-gain observer is applied to estimate the unmeasureable states of the system. Strict analysis of the nonlinear control system is given. Experimental results are provided to support the theoretical results.