Research On Partition Software For Train Control Safety Computer Platform Based On Virtualization

With the rapid development of high-speed railway and urban rail transit,the functional requirements of the train control system are increasingly complicated,such as high-density traffic control,energy-saving optimization,unmanned.Safety computer is an important role supporting the train control system applications,the complexity of real-time software on its platform was also more obvious.For the trends of safety and reliability caused by the increasingly complicated software on train control system,a design method of multi-application safety computer partition software based on virtualization was proposed in this paper.Firstly,the characteristics of train control safety computer and the requirements of domestic and international software safety standards are analyzed,then ideas of modular and abstracted,and the safety software kernel technologies in complex systems were determined.According to the requirements about safety,the theory and application of partition software based on virtualization were studied,which shows that the partition software was suitable for solving the software complication problems faced by the safety computer platform.At the same time,it was also demonstrated that the concurrency and sharing features of the partitioned system posed a safety risk to the train control system,then several typical methods of concurrent system safety were summarized,and the formalized verification based on the concurrent separation logic were alse proposed.Then,according to the design requirements of fault-tolerant,real-time and hierarchical,the design of partition software was carried out from the four aspects,they were time-space isolation mechanism,concurrency control strategy,inter-partition communication mechanism and real-time fault tolerant scheduling algorithm.Firstly,according to the design goal of fault isolation,a space isolation method based on memery mamage unit(MMU)and a time separation model based on forced time scheduling were respectively proposed to meet the requirements of fault isolation;Secondly,a concurrent control mechanism based on transactional memory system was designed.And it uses the concurrent separation logic and invariant proofs to formally verify the mechanism.The results show that this mechanism can ensure the correctness of concurrent system programs.Thirtly,in terms of the inter-partition communication mechanism,according to the requirements like as real-time and reliability,a real-time communication mechanism based on client-server(C/S)model was designed.Lastly,in real-time fault-tolerant scheduling strategy,the improved periodic scheduling algorithm based on constant bandwidth scheduling algorithm(CBS)was designed,which have used dynamic strategy.So that it have improved the real-time of the safety computer with this scheduling algorithm.At the same time,the primary and secondary version mechanism have been used to achieve redundancy fault tolerance with partition.Finally,the prototype of partition software was designed and tested on the double two vote of two safety computer platform.The results show that the existing platform can safely run with different periodic applications with the partition software.And the system realizes the functions of fault isolation,concurrent safety and real-time fault-tolerant scheduling,and meet the requirements of safety and reliability of train control safety computer.