Sliding Mode Controller Design for Gap Control in Virtual Coupling of Rail Vehicles

Abstract

This thesis focuses on investigating the feasibility and performance of a Sliding Mode Controller (SMC) for gap control in Virtually Coupled Train Sets (VCTS) compared to a previously built PID based gap controller. A literature study on SMC and its application in similar contexts was conducted, followed by the development of a simulation framework capable of simulating train and platoon dynamics. The SMC based gap controller was designed and implemented in the framework, and several performance indicators were identified and mathematically defined for evaluation. Various scenarios were simulated to assess the controllers’ performance, and the findings revealed that the SMC controller effectively regulated the gap and handled coupling and decoupling maneuvers with adaptive time headway. Performance indicators, such as actuation energy and time, velocity, and gap overshoot, were used to compare the controllers, and it was observed that the SMC controller outperformed the PID controller in terms of maneuver execution efficiency. The simulations also highlighted the influence of different distance policies, with the controllers exhibiting less overshoot using the Constant Distance Headway (CDH) policy compared to Constant Time Headway (CTH). However, the presence of noise posed a limitation, as the chattering behavior could not be fully eliminated in the SMC controller. The developed simulation framework provides a foundation for future enhancements, such as accommodating multiple trains for string stability evaluation and incorporating stations and stops for a more realistic VCTS simulation. The simulation framework also enables further optimization of the controllers based on specific requirements.