Magnetic Sensor Self Test via Wire-on-Chip
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Solution Overview
Problem
Current magnetic sensor systems in safety-critical applications face challenges in identifying failed sensors without additional redundancy, leading to increased costs and potential system shutdowns, as they cannot determine which sensor is failing.
Innovation Solution
Implementing a 'wire-on-chip' (WOC) device on the sensor chip to generate a current flow and compare actual sensor outputs with expected outputs caused by a WOC magnetic field, allowing for self-testing and verification of sensor functionality using an electronic control unit (ECU) with integrated energy storage to manage high current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundancy is used to achieve safety integrity level, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The sensor performs self-diagnostics using an integrated WOC device that generates a magnetic field to stimulate the sensing element. The sensor autonomously tests its own functionality by comparing expected output signals with actual output signals, eliminating the need for additional redundant sensors while maintaining safety integrity requirements.
Solution Approach 2:
The sensor chip is designed to perform both its primary sensing function and self-diagnostics function through the integrated WOC device. This multi-functionality allows a single sensor to replace what would traditionally require multiple sensors (one for sensing, additional ones for redundancy), reducing overall system complexity while maintaining reliability.
2Reliability
If redundancy is used to identify failed sensors, then reliability is improved, but cost increases
Solution Approach 1:
The sensor autonomously identifies its own failure condition by performing self-diagnostics through the WOC device. The sensor compares its actual output signal with the expected output signal generated by the WOC magnetic field, enabling it to detect its own malfunction without requiring additional sensors for comparison or redundancy.
3Reliability
If self-test is implemented using WOC device, then reliability is improved, but use of energy increases
Solution Approach 1:
The self-diagnostics function is activated periodically or on-demand rather than continuously. The WOC device is stimulated only when self-test is required, allowing the sensor to maintain low power consumption during normal operation while periodically verifying its functionality through the self-test mechanism.
Solution Approach 2:
The system performs self-diagnostics proactively before actual sensor failure occurs. By periodically testing the sensor's functionality using the WOC device, the system can detect potential issues early and take preventive measures, ensuring reliability without requiring continuous high energy consumption for monitoring.
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 effective verification of sensor functionality, reducing the need for redundant sensors and maintaining system operation by identifying faulty sensors, thus enhancing safety integrity levels without excessive cost or shutdowns.
Implementation Method 1
a wire-on-chip (WOC) device disposed next to the sensing element... drive the WOC to create a WOC magnetic field
Data Source
AI summary
The disclosure provides a system for magnetic self test. The system includes an electronic control unit (ECU) including a controller. Only one sensor is electrically coupled to the ECU, wherein the sensor includes a sensing element, a signal conditioning element electrically coupled to the sensing element and the controller, and a wire-on-chip (WOC) device disposed next to the sensing element. The system further includes a WOC stimulus element provided in the ECU or the sensor to drive the WOC to create a WOC magnetic field, wherein the system is configured to compare an expected sensor output signal that is caused by the WOC magnetic field with an actual sensor output signal by the controller or an additional signal assessment element in the sensor to identify whether the sensor is still functioning correctly.