Modelling of railway vehicle suspension system and vibration control

The main objective of this thesis is to model and control the suspension systems of railway vehicles. Since track irregularities are the main vibration source for railway vehicles, the railway track structure and track irregularities were examined in detail in the thesis. The Hunt linear track model was adapted to the vehicle model and simulation studies were carried out. In addition, for the measurement data taken from the Konya-Polatlı high-speed main line, an analytical model with the characteristics of these data was created using statistical methods. To investigate the railway vehicle performances, half-car and full-car models of the vehicle were obtained. Semi-active and active controllers were designed that can increase passenger comfort and safety. The skyhook and groundhook variable value dampers are used for semi-active controllers. Gradient-based method and linear matrix inequalities were used to solve the problem that finding optimal values of these dampers. As a solution method to active controller design problem, H2, Hinf with H2/ Hinf modern control methods and the LQG method have been used. Polytopic vehicle suspension models were obtained for the uncertainty of the vehicle body mass and the Hertzian spring stiffness, whose value could not be determined clearly. Active controllers were synthesized for these polytopic models. We synthesized low-order controllers by using MATLAB HIFOO toolbox. All theoretical results were compared regarding bode diagrams and the RMS values of vehicle response. The vehicle model has been updated to include flexible and rigid modes. With the active controller design, rigid and flexible modes have been suppressed.