Research Of Synchronization In Triple Modular Redundancy System

Railway signal control systems applied in China are safety-critical one. Once suffering failure, not only economic loss will be resulted, but also their personal safety of people may be endangered. This calls for extraordinarily high request on safety and the reliability of these systems. Triple Modular Redundancy (TMR) system may perfectly satisfy such requirement on high reliability and safety.In a TMR system, as three computers are involved in the frequent comparison, the synchronization between these computers becomes the key technology, as the implementation of which will direct influence the correctness of functions and effectiveness of operations. Generally, a TMR system can be achieved with from synchronization methods: with hardware, or via software. The software based approach is widely adopted because of the high requirements of the hardware in the former synchronization method. This dissertation uses the software based task synchronization and achieves the comparing and voting of data in process states and application, by setting multiple voting points in one task, thus successfully solves the pivotal difficulties in processing the voting of data states and procedure states in the synchronization.First of all, this dissertation introduces the development situation of fault-tolerant computers and the main contents of research activities involved. After that, TMR systems based on hardware and software synchronization are introduced, and the task synchronization approach applied in this dissertation is discussed by using computer-based interlocking with software redundancy, as the solution under research. In the third chapter, the pattern of the system synchronization approach is constructed with Petri net, and analysis to its performance is also provided. Moreover, the detailed implementation of this synchronization process is expatiated, with introduction to key points of the synchronization process. The reliability of a TMR system is highly related to the synchronization strategy applied. The synchronization approach introduced in this dissertation makes possibility to the effective synchronization among redundant modules and thus ascertains the reliable, real-time and uninterrupted operation with security, of a TMR system.