Position tracking control of magnetic levitation system based on continuous sliding mode control*

摘要

In this paper, aiming at the problem of position tracking control of magnetic levitation system under parameter uncertainties and unknown external disturbance, a continuous sliding mode control(CSMC) method based on extended state observer(ESO) is proposed. Firstly, in order to suppress the adverse effects of disturbance and system unmeasurable states on control performance, an ESO for the system was designed to estimate system disturbances and unmeasured states. Meanwhile, in order to improve the robustness of the system and eliminate the chattering phenomenon caused by the high-frequency switching function in the sliding mode control law, a position tracking controller based on continuous sliding mode control is designed. Then combined with disturbance estimation technology and continuous sliding mode control technology, a composite position tracking controller(CSMC+ESO) is designed for the magnetic levitation system. Simulation and experimental results shows that compared with the general continuous sliding mode control(CSMC), the proposed control method improves the tracking accuracy, convergence rate, obtain better anti-interference capability and noise filtering performance for control input.