Abstract:To improve ride comfort in railway vehicles, the suppression of vertical bending vibration and rigid-body-mode vibration in the car body is essential. In this paper, a system is proposed that aims to reduce bending and rigid-body-mode vibration simultaneously by introducing damping control devices in the primary and secondary suspensions. The technique involves a control system of primary vertical dampers and air springs; the former are used to suppress the first bending mode vibration; the latter, to suppress the rigid-body-mode vibration. The results of both simulations and vehicle running tests on the Sanyo-Shinkansen line demonstrate that this system reduced vertical vibrations in the bogies and the car body using the sky-hook control theory. In the running tests in particular, the system reduced the vertical vibration acceleration PSD peak value in the first bending mode to almost 20 per cent and in the rigid body mode to almost 50 per cent compared with the case when the system was not used. As a result, the ride quality level L T (a widely used index of ride comfort in Japan) decreased by at least 3 dB, indicating greater ride comfort.

To improve the riding comfort of railway vehicles equipped with the air suspension system now in widespread use, we tested a semi-active air suspension control system with a variable orifice. The system is installed between the air spring and the auxiliary air chamber, and is adjusted using a controller with a design based on the H ∞ control algorithm. We carried out numerical simulations using a half railway vehicle model with a 4-element air suspension model, as well as performing excitation tests using a half carbody at a rolling stock test plant. The results show that the proposed system effectively reduces the power spectral density (PSD) of acceleration of the carbody floor. Additionally, little difference was observed between the vibration mitigation effectiveness of a reduced-order controller and that of the original one.

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Suppression of the vertical bending vibration of carbodies has recently become essential in improving the ride comfort of railway vehicles. In this paper, we propose a method of controlling vibration in the primary suspension of rolling stock to reduce carbody vibration. Systems conceivable for this purpose include a semi-active suspension system with variable axle dampers that can control damping force continuously by command current to the damping force control valve. Based on LQG control theory, we carried out numerical simulations and performed excitation testing with a carbody equivalent to an actual Shinkansen vehicle fitted with variable axle dampers to selectively suppress the first mode bending vibration of the carbody. The results show that this LQG control method reduces the power spectral density (PSD) of acceleration on the floor more effectively than the sky-hook control method, which does not consider the vibration modes of the carbody.