Modeling and Stochastic Analysis of Embedded Systems Emphasizing Coincident Failures, Failure Severity and Usage-profiles

by Kshamta Jerath, M.S. Washington State University August 2002 Chair: Frederick T. Sheldon The increasingly ubiquitous use of software systems has created the need of being able to depend on them more than before, and of being able to measure just how dependable they are. Knowing that the system is reliable is absolutely necessary for safety-critical systems, where any kind of failure may result in an unacceptable loss of human life. This study models and analyzes the Anti-lock Braking System of a passenger vehicle. Special emphasis is laid on modeling extra-functional characteristics of coincident failures, severity of failures and usage-profiles the goal is to develop an approach that is realistic, generic and extensible for this application domain. Components in a system generally interact with each other during operation, and a faulty component can affect the probability of failure of other correlated components. The severity of a failure is the impact it has on the operation of the system. This is closely related to the notion of hazard which defines what undesirable consequence will potentially result from the incorrect system operation (i.e., threat). Usage profile characterizes how the system is used for the purpose of modeling and reliability analysis. Only those failures that occur