Estimator-based multiobjective robust control strategy for an active pantograph in high-speed railways

Active control of the pantograph is one of the promising measures for decreasing fluctuation in the contact force between the pantograph and the catenary. In this paper, an estimator-based multiobjective robust control strategy is proposed for an active pantograph, which consists of a state estimator and a robust H_∞ controller. The former serves as an essential tool for obtaining the states of the pantograph considering randomly missing measurements, and the latter is employed for decreasing the contact force fluctuation considering the limitation of the control force and collector uplift. Control performance is evaluated by implementing the control strategy with a nonlinear pantograph–catenary system model, in which the catenary is modeled based on nonlinear cable and truss elements. The robustness of the proposed control strategy is investigated under parameter perturbations and environmental disturbance, respectively. Furthermore, its advantage is verified by comparing it with an existing controller. Simulation results show that the control strategy can decrease the fluctuation in the contact force and reject parametric uncertainties and stochastic wind field.