Redundant Sensor Signal Path Diagnostics for Offset Error Detection
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Solution Overview
Problem
Magnetic field sensors in safety-critical applications, such as automotive control systems, face challenges in ensuring functional safety due to potential errors in sensor signal processing, which existing technologies fail to adequately address through redundant circuits or self-test capabilities.
Innovation Solution
The implementation of redundant signal paths and diagnostics within sensors to assess and compare characteristics like offset and gain between processing channels, generating fault signals to indicate errors and potentially place the sensor in a safe state, thereby enhancing fault detection and system reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant signal paths are implemented in sensors, then reliability is improved, but device complexity increases
Solution Approach 1:
The sensor is divided into multiple independent signal paths (first signal path including first sensing element and first front end, second signal path including second sensing element and second front end), each capable of independently sensing and processing the same physical quantity. This segmentation allows redundancy while maintaining functional independence of each path.
Solution Approach 2:
A second signal path is created as a copy of the first signal path, with corresponding sensing elements and front-end circuits. The second path replicates the functionality of the first path, providing redundant measurement capabilities. The copying approach ensures that both paths process the same input through identical circuit architectures.
2Reliability
If self-test capabilities are added to sensors, then reliability is improved, but device complexity increases
Solution Approach 1:
The sensor performs self-diagnostics by automatically comparing the outputs of its own redundant signal paths. The comparison circuitry is integrated within the sensor itself, allowing it to self-test and self-diagnose without requiring external test equipment. The sensor monitors its own health status and can indicate faults internally.
Solution Approach 2:
The comparison result between the first and second front end signals is fed back to indicate whether the difference is within a predetermined tolerance. This feedback mechanism enables continuous monitoring of signal path consistency and provides real-time diagnostic information about sensor health and reliability.
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 effectively identifies and communicates errors, improving the reliability and safety of magnetic field sensors by ensuring that any deviations in offset or gain between redundant channels are within predetermined tolerances, thus preventing system faults and ensuring safe operation.
Implementation Method 1
Some sensors include one or more magnetic field sensing elements, such as a Hall effect element or a magnetoresistive element
Implementation Method 2
Some sensors include one or more magnetic field sensing elements, such as a Hall effect element or a magnetoresistive element
Data Source
AI summary
A sensor includes a first sensing element configured to sense a parameter and generate a first sensing element output signal indicative of the parameter, a first front end element configured to receive the first sensing element output signal and to generate a first front end signal, a second sensing element configured to sense the parameter and generate a second sensing element output signal indicative of the parameter, a second front end element configured to receive the second sensing element output signal and to generate a second front end signal, a difference block configured to receive the first and second front end signals and generate a difference signal indicative of a difference between the first and second front end signals, an absolute value block configured to receive the difference signal and generate an absolute difference signal indicative of an absolute value of the difference signal, and an offset comparator configured to compare the absolute difference signal to an offset threshold to detect whether a difference between an offset associated with the first front end signal and an offset associated with the second front end signal is within a predetermined tolerance.