Sensor Diagnostic Circuits for Fault Detection and Reliability
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Solution Overview
Problem
Magnetic field sensors in safety-critical applications like automobile control systems face failures due to manufacturing or design defects, necessitating effective diagnostic methods to ensure operational integrity and compliance with safety standards like ASIL.
Innovation Solution
A sensor system with a detector, test circuits, and a checker that generates output signals to communicate the operational status of test circuits, allowing for fault detection and safe mode operation without immediate disruption, using a combination of magnetic field sensing elements, analog-to-digital converters, and digital processors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant identical circuits are used to meet safety standards, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the testing function from the redundant circuits by introducing a dedicated checker circuit that tests the test circuits. This allows the redundant circuits to be used for their primary function while the checker provides diagnostic capability, reducing the need for additional redundant testing circuits.
Solution Approach 2:
The checker circuit enables the test circuits to self-diagnose their operational status by testing themselves. This self-service capability allows the system to detect faults in the test circuits without requiring external intervention or additional redundant circuits, thereby maintaining reliability while managing complexity.
2Reliability
If self-test capabilities are implemented, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements self-test capabilities where the test circuits are tested by the checker circuit. This allows the sensor system to perform self-diagnosis and detect faults in the test circuits, improving reliability by ensuring the test circuits are functioning correctly without requiring external testing equipment.
Solution Approach 2:
The checker circuit provides feedback about the operational status of the test circuits to the output signal generator. This feedback mechanism allows the system to detect and report faults in the test circuits, improving reliability while the integrated nature of the feedback keeps the added complexity minimal.
3Reliability
If fault detection is implemented, then reliability is improved, but ease of operation deteriorates
Solution Approach 1:
The patent incorporates feedback mechanisms where the checker circuit continuously monitors the operational status of the test circuits and provides this information to the output signal generator. This feedback allows the system to automatically detect and report faults, improving reliability while maintaining ease of operation through automated fault detection rather than manual intervention.
Solution Approach 2:
The test circuits perform self-testing through the checker circuit, automatically detecting their own faults without requiring external operation or intervention. This self-service capability improves reliability by ensuring continuous monitoring while maintaining ease of operation as the system manages its own diagnostic functions.
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
Enables continuous operation and fault logging without automatic safe state transitions, ensuring system reliability and compliance with safety standards by providing a 'check of the checks' mechanism for sensor test circuits.
Implementation Method 1
Some sensors include one or magnetic field sensing elements, such as a Hall effect element or a magnetoresistive element, to detect aspects of movement of a ferromagnetic article
Implementation Method 2
Some sensors include one or magnetic field sensing elements, such as a Hall effect element
Implementation Method 3
Some sensors include one or magnetic field sensing elements, such as a Hall effect element or a magnetoresistive element
Data Source
AI summary
A sensor includes a detector configured to sense a parameter, at least one test circuit configured to detect a respective fault condition of the sensor and generate a fault signal in response to detecting the fault condition, a checker configured to test the at least one test circuit to determine the operational status of the at least one test circuit, and an output signal generator, coupled to receive the sensed parameter, the fault signal, and the operational status of the at least one test circuit. The output signal generator is configured to generate an output signal of the sensor to communicate the sensed parameter and the operational status of the at least one test circuit.