Active control of lateral vibration in a structurally modified train car

As trains are continually designed for higher speeds the problem of railcar vibration grows worse. Lateral vibrations in a train car are noticeable to passengers if the frequency contents are lower than approximately 20 Hz, and complaints of nausea are not uncommon. The passive solution of stiffening the car chassis to shift the vibrational frequencies higher results in inflated manufacturing and running costs, and opposes higher travel speeds due to increased weight. Semi-passive solutions, such as modifying the structural dynamics of the carbody by decoupling heavy underfloor equipment, do not sufficiently reduce the vibrations. However, by appending a multi-reference feedforward active vibration controller, a substantial reduction in the lateral vibration level is to be expected. Based on a dynamic computer model of a train car simulating the lateral vibration, which uses as input bogie acceleration data measured on a running train, multiple-input/single-output coherence spectra were estimated to determine a suitable set of reference signals to an active control system. A dual-reference controller implies a theoretical maximum attenuation of 28 dB at the objective frequency of 10 Hz. Control simulations are carried out using different reference signal combinations. Preliminary results indicate lateral vibration attenuation on the order of 15 dB.