Metros have the problems of passenger crowding during the peak hours and waste of transport capacity during the non-rush hours. Virtual coupling (VC) is expected to be a good solution to this problem, by which train formation can be dynamically adjusted, thus the line capacity is adjusted. This paper introduces the concept and relevant research of VC, and the existing problems and possible solutions are presented. Train protection and operation control methods are two most important problems among them. For the former, although relative braking distance principle is adopted, the space-time relationship between successive trains is omitted, thus, a space-time-separation-based train protection principle is proposed in this paper; for the latter, most of the existing studies only focus on the cruising control of VC, while the problem of non-synchronous parking that exists in the process of VC arrival at a station is wrongly ignored, which is particularly important in metros, a cooperative-control-based train following method is presented to solve this problem. This paper can provide a reference for readers to understand the development trend of virtual coupling technology in metros and to engage in relevant research.

Metro  /  virtual coupling  /  train operation  /  train protection  /  cooperative control