Optimal control for rail vehicle pantograph systems with actuator delays

This study exploits an optimal control approach for solving the general robust control problem of active pantograph suspension systems with actuator delays and time-varying contact force such that both the stabilisation and optimal performance are achieved. On the basis of Bellman´s optimality principle and Razumikhin theorem, the general robust control design problem can be equivalently transformed into an optimal control problem with the amount of matched uncertainties involved in the performance index. A stability criterion has been developed under which the time varying stiffness of contact force and time-delayed actuation force can not only achieve stability, but also acquire the guaranteed level of performance for regulation. A suitable linear state feedback control law is characterised via Lyapunov stability theory to ensure quadratic stability and performance robustness of the closed-loop systems. The effectiveness of the proposed design is demonstrated through simulation studies.