Redundant Signal Path Filter Testing for Fault Isolation
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Solution Overview
Problem
Detecting failures in redundant signal paths within industrial control systems is challenging, especially when the input signal remains constant, as existing methods rely on signal changes to identify faulty components, potentially allowing failed components to go undetected for extended periods.
Innovation Solution
A method and system that generate a test signal at a predefined frequency and inject it into both signal paths, measuring and comparing the frequency responses of filters in each path to identify any differences exceeding a threshold, thereby determining if a failure has occurred, regardless of the input signal state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diagnostic programs compare digital values from redundant signal paths, then safety faults can be detected, but the specific location of the fault cannot be identified without further investigation
Solution Approach 1:
The patent segments the fault detection process by injecting test signals at specific points in the signal path and measuring responses at multiple locations. This divides the overall system into testable segments, allowing identification of which specific component (filter, conductor, or sensor) is faulty rather than just detecting that a fault exists somewhere in the redundant path.
Solution Approach 2:
The patent introduces test signals as intermediary elements to diagnose the system. These test signals act as mediators that interact with potential fault points, allowing the diagnostic system to locate faults by analyzing how the test signals are affected at different measurement points without requiring direct access to or disassembly of the suspected faulty components.
2Reliability
If the system relies on changing input signals to detect component failures, then constant signals cannot reveal failed components, but generating additional test signals increases system complexity
Solution Approach 1:
The patent makes the existing signal paths multi-functional by using them both for normal operation and for diagnostic testing. The same conductors and filters that carry process signals are also used to carry test signals, eliminating the need for separate dedicated test equipment and reducing overall system complexity while maintaining reliable failure detection.
Solution Approach 2:
The system performs self-diagnosis by using its own existing infrastructure to generate and analyze test signals. The redundant signal paths serve their primary function while simultaneously serving as their own diagnostic tools, detecting failures without requiring external testing equipment or increasing system complexity.
3Ease of repair
If technicians must conduct further investigation to identify fault sources, then maintenance time increases, but automated diagnostic systems increase device complexity
Solution Approach 1:
The patent performs preliminary diagnostic actions automatically by analyzing test signal responses and identifying the specific location of faults before technician intervention is needed. The system pre-processes diagnostic information and presents ready-to-act fault location data, eliminating the need for technicians to conduct time-consuming manual investigations while keeping the automated system relatively simple.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the precise identification of failed components in redundant signal paths, even when the input signal is constant, ensuring timely detection and maintenance, thereby enhancing the reliability and safety of industrial control systems.
Implementation Method 1
A test signal is generated at a predefined frequency. The test signal is injected into a signal path. A frequency response of the filter in the signal path is determined based on the test signal and an output signal from the filter.
Data Source
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AI summary
A system and method for detecting a failure in a redundant signal path during operation of the redundant path is disclosed. A test signal is sequentially injected into each signal path while an input signal is conducted by the other signal path not receiving the test signal. The test signal is selected at a frequency to verify operation of a filter connected in series along each path. A processor generates the test signal, injects the test signal at the input of the filter, and receives the output of the filter. The processor then generates a frequency response of the filter in each signal path as a function of the output from the filter and of the original test signal. The frequency response obtained along each of the redundant signal paths is compared to each other to detect a failure of one of the filters present along the respective signal paths.