Model-based controller design for a lift-and-drop railway track switch actuator

Track switches are essential in order to enable railway vehicles to change routes; however, they are also the largest single cause of failure on the railway network. A new generation of switching concepts are emerging from projects like In2Rail, REPOINT, and S-Code that promise to improve rail network performance through the use of new mechanisms, monitoring, and control systems. This paper focusses on modeling and control of a lab-demonstrator from the REPOINT project. Unlike conventional track switch machines, this actuator needs closed loop feedback control. First, a detailed simulation model of the actuator is developed and validated against experimental results. Two model-based control designs are then developed and tested: a classical cascaded P/PI controller and a modern state feedback controller. The two controllers are compared and it is found that, whilst there are some performance differences, both meet the requirements for use in a redundantly actuated REPOINT switch.