Mixed-Layer Fault Tree Modeling Across Logical and Physical Layers
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Solution Overview
Problem
Current safety assurance methods for complex systems, such as safety-critical systems in aerospace, healthcare, and automotive, lack a systematic approach to generate and maintain fault trees, leading to confusion and error-prone maintenance due to the mixture of different abstraction layers.
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 top failure events, elements, input/output ports, and interconnections from both layers, enabling semi-automated and reusable fault tree creation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fault trees are built manually mixing logical-functional and physical layers, then expert knowledge can be utilized, but confusion and errors increase due to lack of systematic approach
Solution Approach 1:
The patent segments the fault tree into distinct logical-functional layer and physical layer, with separate element types for each layer. This segmentation allows systematic handling of each layer independently while maintaining their relationships through port connections, resolving the confusion caused by mixing abstraction layers.
Solution Approach 2:
The patent introduces ports as intermediary elements that connect the logical-functional layer and physical layer. These ports serve as standardized interfaces that define failure propagation relationships between layers, enabling systematic integration without direct mixing of different abstraction concepts.
2Adaptability or versatility
If manual fault tree construction is used, then flexibility in expert knowledge application is achieved, but maintenance and evolution become cumbersome and error-prone
Solution Approach 1:
By segmenting fault trees into modular layers with standardized element types and port interfaces, the patent enables independent maintenance of each layer while preserving overall system behavior. This modular structure makes evolution and updates systematic rather than error-prone manual operations.
Solution Approach 2:
The patent uses parameter-based definitions for ports and elements, where failure propagation relationships are defined through parameters rather than hard-coded logic. This allows systematic modification of maintenance characteristics while preserving the underlying expert knowledge encapsulated in the model structure.
3Stability of the object's composition
If separate logical-functional and physical fault trees are created, then systematic layer separation is achieved, but integration complexity increases
Solution Approach 1:
The patent merges the logical-functional fault tree and physical fault tree into a unified mixed-layer fault tree model. This merging maintains the stability of separate layer definitions while integrating them through standardized port connections, avoiding the complexity of managing completely separate models.
Solution Approach 2:
Ports serve as intermediaries that systematically connect elements across layers. The port-based interface definition provides a standardized mechanism for integration, reducing the complexity that would otherwise arise from ad-hoc connections between separate fault trees.
Data Source
AI summary
A method for generating a fault tree of a multi-component system is provided. The multicomponent system includes 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 disclosed 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.