Özet:

In this study, a six-degrees-of-freedom half-car model for a freight wagon is used to study the ride motions of the vehicle under random rail inputs. As a rail input, the track profiles taken from Federal Railroad-Administration (FRA) international standard are used. A coupled vertical vehicle-track system is formed as a polytopic function of the track roughness parameter and vehicle speed and their influence on the vehicle dynamics is discussed. Then an optimization problem with a single objective function is formulated for a range of track roughness parameters and vehicle speeds. H_∞ control focuses on obtaining a robustness concerning the uncertainty of the system. So, we used H_∞ optimization to obtain the solutions while maximizing the trade-off between the respective performance indices. Later, a controller with a fixed speed value is synthesized and the results are compared by using the frequency response plots and the root-mean-square values of the car body accelerations and secondary and primary suspension deflections. The simulation results demonstrate that the active system is effective in improving ride comfort while keeping the rail holding within allowable limits.

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