Fast Non-singular Terminal Sliding Controller for Magnetic Levitation Systems: A Disturbance-Observer Scheme

This paper proposes a nonsingular fast terminal sliding mode approach integrated with finite-time disturbance observer (DO-NFTSMC) for a magnetic levitation system exposed to uncertainties and external disturbances. A finite-time disturbance observer is first proposed to handle disturbances and modeling uncertainties. Then a nonsingular fast terminal sliding mode control (NFTSMC) approach is formulated relying on a newly constructed sliding surface to ensure fast transient convergence to the equilibrium. Overall stability and finite-time estimation were verified using the Lyapunov stability theory. Computer experiments using a highly nonlinear magnetic levitation (maglev) system showed promising results in terms of finite-time attainability, disturbance rejection and effective continuous control with reduced chattering. Additionally, performance comparison to that of a dynamic sliding mode control (DSMC) design was carried over and showed that the proposed controller outperformed the DSMC in all aspects.