Research On I/O Acquisition Module Of Trackside Controller Of Tram Signal System

As the rapid development of economy, the pollution of environmental and congestion of road much more serious. The developing of modern tram which have the advantages of economical and practical, moderate traffic volume, green and beautiful and so on, become one of the developing trends of modern urban traffic. In addition, to comparing with the bus,subway, bus rapid transit(BRT), light rail and other transportation methods, modern new trams’ cost and capacity is moderate, and its high ratio of performance to price has attracting more and more people.I/O acquisition module is one modular of switch controller which belongs to modern new tram signal system’s controller next to the rail. And it is important to the traffic safety and efficiency. Currently, the manufacturers of new modern tram in the world such as Germany’s Siemen, France’s Alstom, Canada’s Bombardier Inc. and others are foreign companies, but the R&D about modern tram in our courtry is not much. The research on the tram signal system mostly focused on the discussion of framework, there is little literature specific to a particular part of product’s R&D. In this context, this paper, to service to the trackside controller of signal system, developed a highly reliable safety I/O acquisition system for the relevant signal’s acquisition. In addition, the research also laid a solid foundation for the modern new tram system localization signal.First of all, introduced the current development of the tram signal system and trackside controller, clear the function requirement of I/O acquisition module accrording to the tram signal’s characteristics and the external interface characteristics. Putting forward strict rule propose to I/O acquisition module according to the fail safe principle.Secondly, analyzing and designing the hardware circuit and software flow chart of I/O acquisition module. The system uses two take two work structure. In the aspect of hardware design, the overall structure of the circuit are introduced in detail, followed by analysis of the circuit design and working principle of the micro controller control circuit, sampling circuit and communication and interface circuit etc..For the software design, proposed security requirements and software sub module structure of the software about the I/O acquisition module, based on the software design technology firstly, and studyed the acquisition scheme. Introducing the software sub module’s working principle and designing flow chart in detail which include microcontroller’s initialization, module’s communication, synchronization and acquisition. What’s more,emphatically analyzes the communication protocol of synchronous processing and CAN communication and the security analysis of CAN communication.Finally, using RAMS analysis method such as fault tree analysis and reliability blockdiagram to analysising I/O acquisition module’s reliability, maintainability, usability, security,by some qualitative analysis and quantitative calculation. Firstly, according to the reliability block diagram by using the components’ basic failure rate get module’s MTBF; and then through the qualitative analysis of the modules get it’s MTTR, and according to MTBF and MTTR get the module’s availability; finally, establishing a fault tree of modules, and of the quantitative analysis, get the module’s risk rate. The conclusion shows that the RAMS index can meet the relevant requirements of the I/O acquisition module.The results show that the design of this module is stable and reliable, the reliability,maintainability and usability are fully meet the relevant standards, safety grade reaches SIL4 grade. Therefore, this paper’s design and analysis’ result has great significance for the design of tram signal system in future, which is aiming I/O acquisition at the tram signal system controller next to the rail. And the design have important reference value to the future system’s operation, maintenance and improvements.