Application of Vague set to Software rating ascertainment for space camera

Software rating ascertainment is very important in development of space camera software system. It can guide the software measurement and management, and help designer improve system reliability finally. Fault Tree Analysis is a common method to analyze the danger reason and fix on bottom events. The most significant step is calculating the occurrence probabilistic of top event, namely the occurrence probabilistic of dangerous event. Because software failure cause is anfractuous and available data are hard to get, a modeling method for bottom event is proposed based on Vague set to calculate the occurrence probabilistic of top event. Experimental results show that the new approach of Vague set can guide the Software rating ascertainment which is ascertained using qualitative analysis. The results also show that the new method makes software rating ascertainment have the quantificational evidence.