Mixed-Layer Fault Trees for Multi-Component Safety Analysis
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Solution Overview
Problem
Current safety assurance methods for complex systems, such as safety-critical systems in aerospace, healthcare, and automotive, face challenges in systematically generating and maintaining fault trees, leading to confusion and error-prone maintenance due to the mixture of different abstraction layers, especially in larger and more complex systems.
Innovation Solution
A computer-implemented method for generating a mixed-layer fault tree that combines logical-functional and physical system layers, allowing for the systematic creation and modification of comprehensive component fault trees by integrating failure propagation models from both architectures, enabling easy extension and reuse during the system's life-cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fault trees are built manually combining logical-functional and physical layers, then comprehensive safety analysis is achieved, but confusion and error-prone maintenance occur in larger and more complex systems
Solution Approach 1:
The patent segments the fault tree into distinct logical-functional layers and physical layers, allowing each layer to be developed, analyzed, and maintained independently. This segmentation resolves the contradiction by maintaining comprehensive safety analysis through layered decomposition while improving maintainability by isolating modification impacts to specific layers rather than requiring full-tree revisions.
Solution Approach 2:
The patent introduces an intermediary mapping layer that connects logical-functional elements to physical elements. This intermediary structure enables comprehensive safety analysis by preserving the relationship between abstract safety requirements and concrete physical components, while simultaneously improving maintenance by providing a clear translation path that reduces confusion when modifying either layer.
2Reliability
If mixed-layer fault trees are used to represent both logical-functional and physical layers, then comprehensive system coverage is achieved, but complexity and difficulty in maintenance increase
Solution Approach 1:
The patent divides the fault tree structure into separate logical-functional segments and physical segments, each with its own internal consistency and validation rules. This segmentation achieves comprehensive system coverage by ensuring both layers are represented, while reducing apparent complexity by allowing analysts to work within the boundaries of individual layers without constantly navigating the entire mixed structure.
Solution Approach 2:
The patent adds a dimensional separation between logical-functional representation and physical representation, organizing the fault tree along multiple abstraction dimensions rather than mixing them in a single flat structure. This dimensional organization achieves comprehensive coverage by capturing both abstract safety logic and concrete physical failures, while managing complexity by providing clear navigational paths through each dimension independently.
3Reliability
If manual construction of fault trees is performed, then expert knowledge can be incorporated, but systematic generation and consistency are difficult to maintain
Solution Approach 1:
The patent performs preliminary action by establishing standardized templates and structures for both logical-functional layers and physical layers before populating them with specific system details. This preliminary framework incorporation allows expert knowledge to be systematically integrated into predefined safety logic patterns, while maintaining consistency through the predetermined structure, thereby easing the generation process by reducing ad-hoc decision-making.
Solution Approach 2:
The patent implements feedback mechanisms that validate the consistency between logical-functional elements and physical elements during fault tree construction. This feedback loop ensures expert knowledge is properly integrated by checking whether the physical implementation matches the intended safety logic, while systematically maintaining consistency through automated validation rules that prevent contradictory configurations.
Data Source
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AI summary
The present invention pertains to a method for generating a fault tree of a multi-component system. The multicomponent system comprises a logical-functional system layer and a physical system layer as different layers of abstraction. The physical system layer may correspond, for example, to software and/or hardware implementing the functional aspects of the logical-functional system layer. The method first provides a logical-functional fault tree for the logical-functional system layer and a physical fault tree for the physical system layer, the latter having elements corresponding to elements in the logical-functional fault tree. Next, a mixed-layer fault tree is generated by combining aspects of both fault trees in a systematic way. The present invention is particularly relevant for analyzing safety-critical systems. However, the present concepts are not limited to these applications and may be applied to general use cases where fault tree analysis is applicable. The solution of the present invention advantageously provides a systematic approach to generate fault trees taking into account both the logical-functional and the technical-physical aspects of a multi-component system. The resulting fault tree can thus be easily extended, modified and/or reused during a system's life-cycle.