Hydraulic actuation system with active control for the lateral suspensions of high speed trains

Abstract

High speed trains normally use actively controlled pneumatic systems to recentre the car body with respect to the bogie when the train negotiates a curve. Pneumatic systems are used because of their softness, which adds a little contribution to the elastic force generated by the mechanical springs of the lateral suspension system, thereby allowing the necessary dynamic isolation between car body and bogie. However, pneumatic systems have the drawbacks of large dimensions and slow response, often accompanied by a few damped oscillations. An innovative solution was developed that makes use of hydraulic actuators, providing them with artifi cial compliance generated by an appropriate control, hence making the hydraulic actuators suitable for this application. A car body centring system is thus obtained that presents fast response, small volume and a softness comparable to that of a pneumatic system. The optimal control law for this system was defi ned, the system dynamic characteristics were analysed and a technological demonstrator was built to assess the system merits. The paper outlines the theoretical grounds for the system control, its performance and the most signifi cant results obtained during a test campaign conducted on the technological demonstrator.