Control design for a high speed railway vehicle via fixed and non-fixed order optimization

In this paper, the Root-Mean-Square (RMS) responses of the heave and pitch accelerations, the suspension travels, and the wheel deflections of a high-speed railway vehicle excited by random road inputs are studied. The road excitations at the front wheels are modelled by a second-order linear shape filter driven by white-noise inputs; and the temporal correlations between the front and the rear wheels are predicted by second order Pade filters. The derived model is used to study the influence of correllation structure on the ride performance of the actively controlled railway vehicle. Next, a multi-objective control problem is formulated as a nonconvex and nonsmooth optimization problem with controller order restricted to be less than or equal to the passive system model order. For a range of orders, controllers are synthesized by using the HIFOO toolbox.