Switching logic-based robust control for trajectory control of levitation systems of maglev trains with external disturbances

Maglev vehicle is one of the important directions for the future development of rail transport, as it has the features of low operational energy consumption, strong climbing ability and environmental friendliness. The operation process of maglev vehicle is inevitably affected by random external disturbances such as track structure discontinuity, aerodynamic lift and passenger number change. At the same time, the levitation system of maglev vehicle has extremely complex nonlinear characteristics and is an open-loop unstable system, which brings challenges to the high-precision control of the levitation system. Previous studies have considered external disturbances as harmful disturbances and designed various control algorithms to suppress them. However, not all external disturbances are harmful, and some of them are favourable to the stable levitation of the maglev vehicle. Neglecting the favourable nature of external disturbances will significantly reduce the levitation control performance and substantially increase the energy consumption of the system. Therefore, this paper designs a nonlinear disturbance observer to estimate the unknown disturbances of the system, proposes a disturbance evaluation method to distinguish between harmful and beneficial disturbances, and introduces it into the controller to improve the levitation system control performance by utilising the beneficial disturbances. In addition, the proposed controller is designed based on a nonlinear model of the levitation system and does not require an exact system model, and has better performance even when the system is far away from the equilibrium point and under the system parameter uptake. Simulations verify the effectiveness and robustness of the proposed control method.