An Actively Controlled Hydraulic Carbody Centering System for the Lateral Suspensions of High Speed Trains

High speed trains normally use pneumatic actuation systems to recenter the carbody with respect to the bogie when the train negotiates a curve. Pneumatic systems are used because of their compliance, necessary to ensure dynamic isolation between carbody and bogie, but have the drawbacks of large dimensions and slow response, often accompanied by a few damped oscillations. An innovative solution was developed using hydraulic actuators with an adaptive control law providing the actuators with artificial compliance, hence making them suitable for this application. A carbody centering system is thus obtained presenting fast response, small volume and the necessary compliance. The optimal control law for this system was defined, the system dynamic characteristics were analyzed and a technological demonstrator was built to assess the system merits. The paper presents the theoretical grounds for the system control, its implementation and performance, and the most significant test results obtained with the technological demonstrator.