Research Of Onboard2-vote-2Computing Platform Of Urban Rail Transit

In Communications-based Train Control system, train-borne equipments are responsible for supervision of train speed, automatic control of braking system and train overspeed protection。It relates directly to affect safety of passengers’life and property。As a control system of high security requirement, a vital computer with software and hardware of high security and high reliability must be Provided as its system platform。At present, domestic research on train-borne safety platform is late started,so there is a large gap between foreign technology and domestic ones。However, with the development of rail transit,safety platform research develops rapidly。The paper focuses on2-vote-2safety kernel unit of train-borne safety platform redundancy structure。Based on the analysis of train-borne safety platform structure, safety-related standards and technical specifications, the paper builds a research platform for train-borne2-vote-2。Through the platform, we analyze, research and realize the key technology of2-vote-2dual-module such as data communication, synchronous processing and data comparisonTrain-borne2-vote-2research platform’s hardware is comprised of single board computer modules, which are based on3U CPCI architecture and including Inter Atom processor-based CPU board,CAN communication card, Ethernet communication card and serial communication card。The platform uses VxWorks embedded real-time operating system to ensure the need of real time。 VxWorks completes its transplantation in hardware platform through the compiling and configuration of BSP and board driver, tailor of operating system component。The platform is divided into four layers:the2-vote-2hardware layer, the operating system layer, the2-vote-2software layer and the ATP application function layer。 Communication between2-vote-2dual-modules on redundant link, which is provided by CAN card, ensures the real-time and reliability of communication。Dual-module synchronization is achieved by combining Software task-level synchronization with clock synchronization。That is, dual-module system sends synchronization message to the other computer at task point or comparison point and waits for a response in real time to realize task-level synchronization。At the same time, after several working cycles, the dual-module system uses clock mutual feedback technology and PTP protocol to do the system clock correction so the clock deviation is limited within a certain tolerance。Data comparison is the core of the system。The paper realizes comparison of dual-module software through strategies like data classification comparison, and provides interface to ATP application function and2-vote-2platform。 The Implementation of train-borne2-vote-2research platform and the key technology of2-vote-2dual-module are described in the last of paper。It proves that the whole system can steadily work in a synchronized environment。...