Design Of Vital Computer's Output Module And Its Reliability And Safety Research

With the rapid development of safety technology, high reliable vital computer system has more and more applications in the field of rail transportation, aerospace, energy and so on. In the vital computer system, safety output module is always the most important part, its reliability and safety directly affects the whole system. This paper proposed a novel 2-out-of-3 output module with high reliability and safety which can be used in the triple modular redundancy vital computer system.Firstly, some classic designs of output module were introduced and the methods which can improve the reliability and safety used in them were analyzed. And then, some parameters that used to evaluate the vital computer system's reliability and safety were introduced and the calculation and design methods were described.Secondly, the requirements of 2-out-of-3 vital computer system's output module were described. Two novel voting models were proposed and one of them was proved has higher reliability and safety than the traditional voting model by Markov theory. Depend on the design of the dynamic pulse modulation circuit, the hardware logic voting circuit and the dynamic back detection circuit, the output module board was implemented. And its functions and performance were tested. The results showed that the design of output module can be used in the real vital computer system.Finally, the output module board's reliability and safety were estimated by using the components'failure rates based on MIL-HDBK-217F. The results indicated that this design has high reliability and safety. In addition, the designed output module's failure modes and failure reasons were analyzed by fault tree analysis.