Super-twisting sliding mode control of magnetic levitation systems under disturbance and parametric uncertainty: A comparative study with nonlinear controller

The magnetic levitation system is nonlinear, inherently unstable, and highly sensitive to disturbances and parametric uncertainty, making robust control essential. This paper proposes a super-twisting sliding mode control (STSMC) strategy for the magnetic levitation system and compares its performance with feedback linearization with integral state feedback, backstepping, synergetic control, and conventional sliding mode control (CSMC). The evaluation is conducted through simulations under nominal conditions, external disturbances, and inductance uncertainty. The results show that STSMC provides the best overall performance in terms of rise time, settling time, overshoot, and steady-state error. Under nominal conditions, STSMC achieves the fastest response, with a rise time of 0.0665 s and a settling time of 0.1150 s. Under inductance uncertainty, it maintains zero steady-state error with a rise time of 0.0632 s and a settling time of 0.1138 s. In disturbance tests, SMC-based controllers show the strongest robustness, with STSMC demonstrating the best overall tracking and disturbance-rejection performance.