Development of a HIL railway roller rig model for the traction and braking testing activities under degraded adhesion conditions

The longitudinal train dynamics is controlled by traction and braking on board subsystems, such as Wheel Slide Protection (WSP) system and antiskid device. The integration and mutual interaction between the two systems are continuously increasing on high speed applications, especially when degraded adhesion conditions occur. Traditionally, braking and traction performances should be verified on a full-scale roller rig to avoid expensive on line tests. In this work the authors investigate a complex application in which the braking and traction systems are tested using a full scale roller rig able to perform the simulation of a known wheel-rail adhesion pattern (especially degraded adhesion) applying a HIL (Hardware In the Loop) approach. This approach is also followed by the innovative roller rig built by RFI (Rete Ferroviaria Italiana) and Trenitalia in the Research and Approval Center of Firenze-Osmannoro. The analysis is performed considering the complex interaction between vehicle on board subsystems and the test rig logics and it is validated considering experimental results available from previous research activities acquired by Trenitalia and RFI.