Model-independent Robust Control for Electromagnetic Suspension Systems of Maglev Vehicles

During real operation of the maglev train, the electromagnetic levitation system is susceptible to external disturbances and parameters uncertainty induced by wind, track irregularity, the change of the passengers load, and so on, which make the stable suspension of the maglev vehicle difficult. To address the stability problem of electromagnetic suspension systems for maglev vehicles with external disturbance, unmodeled dynamics and uncertain parameters, this paper designs a proportional-derivative sliding mode controller (PDSMC) without model information. Firstly, according to the dynamic model of electromagnetic suspension system, the design of model-free robust controller is realized by closed-loop feedback. Then, the asymptotic stability of the proposed controller is proved tightly by using Lyapunov's second law and Schur theory. Finally, to verify the performance of the PD-SMC controller on the actual physical system, a set of hardware-in-theloop experiments were conducted on the experimental platform for single-point suspension control. The experimental results are included to illustrate that the proposed control method effectively mitigates the impact of the external disturbances and parameters uncertainty. Specifically, 50.82% reduction of vibration amplitude in vibration amplitude after external disturbance for PD-SMC controller compared to linear quadratic regulator (LQR) controller, and the time to restore the steady state of the system is reduced by 43.17 %.