Semi-Active Suspension Systems for Railway Vehicles Based on Magnetorheological Fluid Dampers

In this paper, a seventeen degree-of-freedom (DOF) model for a full scale railway vehicle integrated with the semi-active controlled magnetorheological (MR) fluid dampers in its secondary suspension system is proposed to cope with the lateral, yaw, and roll motions of the car body, trucks, and wheelsets. The governing equation considering the dynamics of the railway vehicle integrated with MR fluid dampers in the secondary suspension system and the dynamics of the rail track irregularities are developed. The Linear Quadratic Gaussion (LQG) control law using the acceleration feedback is adopted, in which the state variables are estimated from the measurable accelerations with a Kalman estimator. In order to evaluate how the performances of the railway vehicle system integrated with the semi-active controlled MR fluid dampers can be improved, the lateral, yaw, and roll accelerations of the car body, trucks, and wheelsets of a full scale railway vehicle integrated with MR fluid dampers, which are controlled (the semi-active) and uncontrolled (the passive on and passive off) respectively, are analyzed under the random track irregularities based on the established governing equations and the modelled track irregularities. The simulation results not only show the control effectiveness of the railway vehicle with the semi-active suspension system based on MR fluid dampers for railway vehicles, but also illustrate that the semi-active railway vehicle suspension system based on MR fluid dampers combines the merits of the passive on and passive off railway vehicle suspension systems.