Conditional Risk Model Concept for Critical Space Systems Software
A software risk assessment approach described, based on the concept of software conditional risk and the ability to define analytically aided, risk-based software test strategies that seek to optimise test coverage. The functional-input space of the software is subdivided into a set of“condition contexts,” corresponding to operating environments and functional conditions for the space system controlled by the software. The formulation of a“conditional risk index,” based on a probabilistic formulation that expresses critical software risk in terms of“condition coverage,” is then enabled with the aid of a combination of logic modelling, automated test vector generation and software defect rate estimation techniques.
KeywordsFailure Probability Risk Index Condition Context Contingency Mode Attitude Control System
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- Garrett C. and, Apostolakis G., “Context and Software Safety Assessment,” Proceedings of the 2nd Workshop on Human Error, Safety and System Development (HESSD′98), pp. 46-57, Seattle, Washington, April 1-2, 1998.Google Scholar
- Guarro, S., Helgevold, D., and Ewell, G., “Integrating MEMS Quality and Reliability Goals with the Use of Multi-Valued Logic Analysis,” Proceedings of the 2nd International Conference on Integrated Micro/Nanotechnology for Space Applications (MNT99), Pasadena, California, Apr. 11-15, 1999.Google Scholar
- Schneidewind N.F. and, Keller T.W., “Applying Reliability Models to the Space Shuttle,” IEEE Software, pp. 28-33, July 1992.Google Scholar
- Yau, M., Wetherholt M., and Guarro, S., “Safety Analysis and Testing of Critical Space Systems Software,” Proceedings of the 4th International Conference on Probabilistic Safety Assessment and Management (PSAM-4), New York City, NY, September 13-18, 1998.Google Scholar