Process Actuator Fault Diagnosis Using Reference-Property Tests

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Solution Overview

Problem

Existing methods for diagnosing faults in process plants with actuators often fail to clearly identify the cause of faults, leading to unnecessary maintenance efforts and potential system interruptions, as they rely on imprecise identification of fault sources.

Innovation Solution

A diagnostic method and system that utilize a diagnostic database to assign state causes to system-reference-properties and provide test databases for determining diagnostic tests, allowing for unambiguous identification of fault causes by fulfilling necessary conditions through system-actual-property detection and testing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing diagnostic methods are used to identify fault causes, then fault detection capability is provided, but measurement precision of fault cause identification deteriorates

Engineering Contradiction:

Improvefault cause identification precisionVSAvoidinformation completeness for fault diagnosis

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The diagnostic method segments the fault diagnosis process into distinct phases: initial fault symptom detection, systematic evaluation against multiple hypotheses, and progressive refinement through additional tests. This segmentation allows each phase to focus on specific information needs, improving overall diagnostic precision while managing information requirements efficiently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary actions by pre-defining multiple potential fault hypotheses and their associated evaluation criteria before actual fault occurrence. This preparatory structuring enables rapid, precise fault identification when symptoms appear, as the diagnostic framework is already in place to systematically evaluate potential causes rather than searching from scratch.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If comprehensive diagnostic testing is performed to identify fault causes, then measurement precision improves, but loss of time increases

Engineering Contradiction:

Improvefault cause identification precisionVSAvoiddiagnostic time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The diagnostic system applies partial action by selectively evaluating hypotheses based on symptom matching and prioritizing the most likely causes first. Rather than performing all possible tests uniformly, the system performs only the necessary subset of tests required to confidently identify the fault cause, reducing diagnostic time while maintaining precision through targeted evaluation.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system incorporates feedback mechanisms where diagnostic results from initial tests inform subsequent testing decisions. Each test result provides feedback that refines the hypothesis set, allowing the system to converge on the correct fault cause more quickly by eliminating unlikely hypotheses and focusing resources on the most probable causes.

Inventive Principle:

Principle #23Feedback

3Reliability

If multiple potential fault causes are considered, then reliability of fault detection improves, but device complexity increases

Engineering Contradiction:

Improvefault detection reliabilityVSAvoiddiagnostic system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The diagnostic system segments the complex evaluation of multiple fault causes into structured hypothesis groups with defined relationships. Each hypothesis represents a potential fault cause with specific evaluation criteria, and the system systematically evaluates these segmented hypotheses rather than treating all possibilities as a single complex evaluation, making the system more manageable while maintaining comprehensive coverage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system manages complexity by dynamically changing evaluation parameters based on symptom patterns. Different symptom combinations trigger different evaluation strategies and hypothesis prioritizations, allowing the system to adapt its complexity level to the specific diagnostic situation rather than maintaining maximum complexity for all cases.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20240255937A1Method for diagnosing a control-and/or regulating system of a process facility comprising at least one actuator for adjusting a process fluid and control-and/or regulation system

Publication Date: 2024.08.01 SAMSON AG

AI summary

A method for diagnosing a control/regulating system of a process facility having an actuator for setting a process fluid, may include: providing a diagnostic database with assignment of multiple state causes to a respective set of specified system reference properties, where each system reference property is assigned a necessary condition; providing a test database with an assignment of different diagnostic tests for a specified system reference property; detecting an actual system property of the system; determining a first system reference property, the condition of which is satisfied by the actual system property; for at least one state cause with a set of specified system reference properties, for a second system reference property of the set, detecting whether the condition assigned to the second system reference is certain; and ascertaining a diagnostic test the second system reference property.