Automated fault tree generation and risk-based testing of networked automation systems

In manufacturing automation domain safety and availability are the most important factors to ensure productivity. In modern software intensive networked automation systems it became quite hard to ensure which non-functional requirements are related to these factors as well as whether these are satisfied or not. This is due to the prevalence of manual efforts in several analyses phases where complexity of the system often makes it hard to obtain comprehensive overview and thus makes it difficult to ascertain the presence of certain undesired consequences. Since design, development and following verification and validation activities are largely dependent upon the result of the analyses the product is largely affected. To address these problems automated fault tree generation is presented in this paper. It uses distinct modeling artifacts and information to automatically compose formal models of the system. Embedding hardware and network failures it is then ascertained through model checking whether the system satisfies certain safety and availability properties or not. This information is used to compose the fault tree. Proposed approach will improve completeness and correctness in fault trees and will consequently help in improving the quality of the system. Furthermore, it is also shown how the artifacts of this analysis can be used to produce test goals and test cases to validate the software constituents of the system and assure traceability between testing activity and safety requirements.