Self-Diagnostic Sensor Signal Path Using Inverse Processing
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Solution Overview
Problem
Conventional sensor systems, particularly magnetic sensor systems, face challenges in meeting safety standards like ASIL requirements without significantly increasing costs, as they often require duplicating sensors and processing circuitry for self-test capabilities during normal operation.
Innovation Solution
A sensor system with a first forward signal path and a second backward signal path, where the second path performs inverse operations with reduced precision, noise, or power, allowing fault detection without duplicating sensor units or adding multiplexers, by comparing signals at upstream and downstream positions within a predefined tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two identical sensors and processing paths are used to meet ASIL requirements, then reliability is improved, but cost increases significantly
Solution Approach 1:
The patent inverts the conventional approach by using a single sensor with a backward signal path that performs inverse operations to verify the main signal path. Instead of duplicating the entire sensor system, the invention creates a self-testing mechanism where the second path processes the signal in reverse (e.g., if the first path amplifies, the second path attenuates) and compares results, thereby detecting faults without requiring a complete duplicate sensor system.
Solution Approach 2:
The patent creates a simplified copy of the signal processing path that performs inverse operations. Rather than copying the entire sensor and processing chain, it creates a virtual copy through mathematical inversion of the processing operations, allowing fault detection with minimal additional hardware while meeting ASIL requirements.
2Reliability
If redundant functional blocks are implemented for self-tests, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent makes the single sensor system multi-functional by enabling it to perform both normal sensing operations and self-diagnostics simultaneously. The backward signal path uses the same physical sensor but processes signals in reverse to perform verification, allowing the system to serve dual purposes without requiring separate redundant sensor units.
Solution Approach 2:
The sensor system performs self-diagnostics through its own backward signal path, eliminating the need for external monitoring equipment or additional redundant sensors. The system monitors itself by comparing the forward and inverse processing results, thereby providing self-service functionality that improves reliability without adding external complexity.
3Device complexity
If a single-channel analog main signal path is used, then device complexity is reduced, but self-test capability is limited
Solution Approach 1:
The patent introduces feedback by creating a backward signal path that feeds processed signals back for comparison with the forward path. This feedback mechanism allows the system to verify its own operation continuously, detecting faults in the analog signal path without requiring complex digital monitoring systems or additional sensor channels.
Data Source
AI summary
A sensor system for providing a main signal and an error signal, comprising: a sensor unit providing a sensor signal; a first signal processor downstream of the sensor unit, adapted for receiving a second signal equal to or derived from a sensor signal, and for performing a first operations on the second signal so as to provide a first processed signal; a second signal processor for receiving the first processed signal and for performing second operations inverse of the first operations, so as to provide a second processed signal; and an evaluation unit for receiving the second signal and the second processed signal, and for evaluating whether the second signal matches the second processed signal within a predefined tolerance margin, and for providing the error signal.