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 modelling 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.