Proposed Active-Standby Switch of the Digital Output for the Redundant ATO System

Abstract

By taking into account the hot standby structure of the redundant ATO system, the paper discusses the key technologies (including self-inspection feedback and fault clearing) for the digital output in the system and proposes a new method of the digital output in the redundant ATO system to discover any fault of its output channel in a timely manner and carry out the active-standby switch to make the system reliable. With development of the major cities, the rail transit becomes the most important urban public transport. The ATO system (automatic operation control system) provides the automatic control of the train through the improved algorithm to ensure less interferences of the driver with the train, so it plays a vitally important role in smaller operation interval and greater transport capacity. As such, the ATO system is catching ever-increased attention of the people for the reliability. The mainstream ATO systems are believed to apply the hot standby structure to improve the reliability at present. The hot standby-based ATO system has two similar systems of which one operates and the other is in a hot standby status more often than not. The working primary system will automatically switch to the standby one when any fault is detected. The active-standby switch involves that of the dual host server and the dual system communication and output. The paper discusses switch of the dual system output including self-inspection and switch of the fault exported from the channel. 2. Introduction to the System The ATO system is comprised of digital input, host server and digital output in general. However, for the purpose of the hot standby-based ATO system, redundancy is required for these units. By taking into account the restrictions (including space and wiring) of the vehicle, the digital input and output both serve as an individual node at a side of the vehicle, so the same channel shall be applied for the redundant digital input and output before the vehicle is provided. The digital output allows for simultaneous acquisition of the signals in the dual system, while the digital output signal shall be exported from the primary system with the standby one in a waiting state. The primary system which detects any output fault has the active-standby switch to ensure service of the standby system as the primary one before the digital output.