Mode-Specific Fault Tree Generation for Multi-Mode Systems

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Solution Overview

Problem

Conventional fault tree analysis methods are inadequate for complex multi-mode systems with multiple operational modes, as they fail to accurately represent and analyze failure behaviors in varying system states, especially in safety-critical systems with reused components.

Innovation Solution

A method and apparatus for generating a fault tree that incorporates component fault tree elements representing failure-relevant operation modes, allowing for the selection and combination of these elements to create a fault tree that represents system failure behavior, which can be evaluated using Boolean logic to reduce complexity and quantify/qualify failure modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional fault tree analysis methods are used for multi-mode systems, then the analysis process is simple, but the failure behavior in varying system states cannot be accurately represented

Engineering Contradiction:

Improveaccuracy of failure behavior representationVSAvoidcomplexity of fault tree analysis method

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The fault tree analysis is segmented by system modes. Each operational mode (start-up, calibration, degraded, emergency) has its own fault tree representation. This segmentation allows accurate representation of failure behaviors specific to each mode while maintaining manageable complexity through modular analysis structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fault tree analysis transitions from a static conventional approach to a dynamic mode-specific approach. The system dynamically selects and applies the appropriate fault tree model based on the current operational mode, enabling accurate representation of varying failure behaviors across different system states.

Inventive Principle:

Principle #15Dynamics

2Reliability

If mode-specific component fault tree elements are incorporated, then failure behavior in different operational modes can be accurately analyzed, but the complexity of generating and managing fault trees increases

Engineering Contradiction:

Improvereliability of safety analysisVSAvoidcomplexity of fault tree generation process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Component fault tree elements are segmented by operational modes. Each component has mode-specific fault tree elements that represent its failure behavior in particular operational states (start-up, calibration, degraded, emergency). This segmentation improves reliability by capturing mode-specific failure characteristics while organizing complexity through structured modular elements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fault tree analysis incorporates parameter changes based on operational mode. Component parameters and failure modes are adjusted according to the active operational state, allowing the system to accurately reflect how component behavior and failure probabilities change across different modes while systematically managing the complexity through parameter-based adaptation.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If a comprehensive fault tree covering all operational modes is created, then all failure behaviors can be captured, but the analysis becomes computationally intensive and time-consuming

Engineering Contradiction:

Improvecompleteness of failure analysisVSAvoidtime for safety analysis

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The comprehensive fault tree is segmented into mode-specific fault trees. Instead of analyzing one large comprehensive tree, the system divides the analysis into separate fault trees for each operational mode (start-up, calibration, degraded, emergency). This segmentation maintains completeness of failure analysis by covering all modes while reducing computational intensity and analysis time through smaller, focused trees.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The analysis applies partial action by focusing on the fault tree relevant to the current operational mode only. Rather than processing all possible failure modes simultaneously, the system performs partial analysis on the active mode's fault tree, achieving sufficient completeness for the current state while significantly reducing computation time and resource requirements.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS10481989B2Method and apparatus for generating a fault tree for a failure mode of a multi-mode system

Publication Date: 2019.11.19 SIEMENS AG

AI summary

A method and apparatus for generating a fault tree for a failure mode of a multi-mode system which includes a plurality of system components, the method includes the steps of providing component fault tree elements of the system components, wherein each component fault tree element includes at least one component fault tree mode element, representing a failure-relevant operation mode of the respective system component; selecting at least one component fault tree mode element representing a system state of the system; and generating the fault tree by incorporating the selected component fault tree mode elements the generated fault tree representing a failure behaviour of a system state of the system.