Software Safety Assurance Framework And Safety Technology Application

In recent years, the software has taken more and more important role in aerospace launching tasks. Software failure can lead to the failure of whole task even tragedy. It must be avoided especially in manned spaceflight program. How to avoid software failures, and improve software safety has been a very important research task for China aerospace.A well-designed guidebook is needed to carry out software safety assurance. In this guidebook Hazard Analysis and some other frequently used technologies for software safety and reliability can be combined together. And also, effective management is necessary to the assurance activities.First of all, this paper surveys the development of software safety around the world, and summarizes several rules for software safety research. Secondly, a guidebook for software safety analysis and design is proposed. The guidebook includes system safety, Primary Hazard Analysis (PHA), software safety plan, software safety effort, tailoring software safety effort and management in software safety development etc. All of them include the whole tasks and the process of software safety activities. Thirdly, this paper focuses on two safety technologies, SFMEA and SFTA and summarizes their advantages and disadvantages, as well as detail analysis process. At present, the research of software safety assurance is far from enough, extra software tests are needed to ensure software safety sometimes. However, it is a good start to improve the software safety and make sure of the success of the launching tasks.Finally, an enhanced SFTA technology based on Statecharts is proposed on the basis of regular SFTA. It is an advanced graphic software safety analysis technology and designed for real-time embedded software analysis. To validate its feasibility, it is applied to automobile Cruising Control System (CCS), researching the safety for the real-time embedded software requirements. The analysis process is strict to be sure of the result's effectiveness and reliability. As the research of software safety in China is only in its first step, such method makes a good guidance to the software safety requirements analysis for the future.