Application of Oil-Hydraulic Actuator for Active Suspension of Railway Vehicle : Adoption of LQG Control Law to a Scale Model on a Test Apparatus

Active suspensions have been studied to improve the ride quality of railway vehicles. In many cases, pneumatic actuators were employed in these studies. This paper deals with the application of oil-hydraulic actuators, which are expected to have more control effect on the running vibration. They have been examined experimentally by using a 3 d. o. f. half-vehicle model. The LQG control law, in which state variables were estimated from measurable ones on actual railway vehicles, was adopted. The results show the possibility that the controllable frequency range is extended by the oil-hydraulic actuator under practical conditions. The addition of bogie acceleration measurement to body-related measurements provides a significant advantage for the performance. When actual body weight becomes lighter than that of the controller design value, the control performance and the stability deteriorate. Therefore, it is recommended that the empty car body weight be used for design of the active suspension controller. Moreover, the control effect can attain the maximum vibration isolation level if the sampling period is shortened to 2 ms