Railway virtual coupling: A survey of emerging control techniques

This paper provides a systematic review of emerging control techniques used for railway virtual coupling (VC) studies. Train motion models are first reviewed, including model formulations and force elements involved. Control objectives and typical design constraints are then elaborated. Next, existing VC control techniques are surveyed and classified into five groups: consensus-based control, model prediction control, sliding mode control, machine learning-based control, and constraints-following control. Their advantages and disadvantages for VC applications are also discussed in detail. Furthermore, several future directions for achieving better controller development and better controller implementation are envisioned, respectively. The purposes of this survey are to help researchers to achieve a comprehensive understanding regarding VC control, to spark more research into VC, and to further speed-up the realization of this emerging technology in railway and other relevant fields such as road vehicles.