Application of high-redundancy actuation and feedback control to railway track switching

Li, Linxiao ORCID: 0000-0003-1204-6586 (2023). Application of high-redundancy actuation and feedback control to railway track switching. University of Birmingham. Ph.D.

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Abstract

Railway track switch systems are crucial components of the railway infrastructure and serve as the primary means of directing trains from one track to another. Conventional track switch systems operate through an open-loop control system, which energises the motor until the desired displacement of the switching track is reached and then de-energises the motor. However, conventional open-loop control systems have no redundancy, which may lead to failures, causing significant disruptions to train operations and threatening passenger safety. This research aims to fill the gap in the development of closed-loop control strategies for track switches in the UK and to add to the existing literature on control design and redundancy concepts to minimise track switch failures during operation. This thesis aims to design and implement a closed-loop control strategy for innovative actuated railway track switch systems to improve their performance. The focus of the control design is to position and adjust the front toe of the switch rail to ensure quick and accurate movement, enabling the safe passage of trains and thus ensuring the availability and reliability of the whole railway network.
The main research route adopted in this thesis is modelling, simulation, control design, and demonstration. The study establishes a validated and easily implementable track switch model using finite element analysis in MATLAB/Simulink. The feasibility of introducing redundancy into the actuators of the track switch system is then evaluated, followed by the implementation of two advanced controllers, PI (Proportional Integral) and PIP (Proportional Integral Plus), to optimise the motion design. The proposed approach is finally tested in a hardware-in-the-loop environment to validate its effectiveness.
The central idea of this research is that incorporating a closed-loop control mechanism, a redundant design, and a fault-tolerant control strategy into railway track switch systems will significantly enhance their system-level reliability. Experimental results demonstrated that classic and advanced control methods effectively control the switch displacement and meet practical requirements. When applied to HRA (High-Redundancy Actuator) track switch systems, the control method can control the switch effectively and provide a level of fault tolerance. The findings of this study provide evidence for the feasibility and practicality of the proposed HRA and control approaches and can serve as a valuable guide for future railway infrastructure design and maintenance. This research substantially contributes to improving the ability of a track switch to tolerate component-level failures, allowing continued operation after such events. Its implementation in rail could potentially reduce the number of delays to trains caused by track switches.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):