Periodic Rate Sensor Self-Test via Signal Injection
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Solution Overview
Problem
Existing vehicle sensor systems lack a method for periodic self-testing during operation, leading to potential delayed detection of sensor malfunctions, which can compromise vehicle directional stability and safety.
Innovation Solution
A method for testing sensor operation by generating a test signal and comparing the induced output signal to predetermined criteria, with error signals and fault flags generated as necessary, allowing for continuous monitoring of sensor functionality during vehicle operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-testing is limited to initial vehicle start-up, then device complexity is reduced, but reliability deteriorates due to increased operational time between self tests
Solution Approach 1:
The patent implements periodic self-testing during vehicle operation by injecting test signals at predetermined intervals. The test signal is injected into the sensor signal line between consecutive sampled output signals, creating a periodic testing mechanism that occurs during normal vehicle operation rather than only at start-up. This periodic action ensures timely detection of sensor malfunctions while maintaining manageable system complexity through structured, interval-based testing.
2Reliability
If periodic self-testing is implemented during vehicle operation, then reliability is improved, but device complexity increases due to additional test signal injection and monitoring circuitry
Solution Approach 1:
The patent merges the test signal injection function with the existing sensor signal processing path. The test signal is injected into the sensor signal line at a point where it combines with the normal sensor output signals, and both are processed through the same signal conditioning and sampling circuitry. This merging approach enables periodic testing without requiring separate dedicated testing hardware paths, thereby improving reliability while limiting the increase in device complexity.
Solution Approach 2:
The signal conditioning circuit performs dual functions: it processes both normal sensor output signals and injected test signals through the same processing path. The sampling circuit and comparison logic are used universally for both operational signal processing and self-testing, eliminating the need for separate dedicated testing hardware. This multi-functionality approach enables periodic self-testing while maintaining reasonable system complexity.
3Measurement precision
If test signal is injected between consecutive sampled output signals, then measurement precision is maintained, but device complexity increases due to precise timing requirements
Solution Approach 1:
The system determines in advance the optimal timing for test signal injection by analyzing the timing relationship between sampled output signals. The test signal is injected at a predetermined interval that is synchronized with the sampling sequence, ensuring it occurs between consecutive sampled output signals. This preliminary timing determination and synchronization approach allows precise test signal injection without requiring complex real-time timing control mechanisms.
Data Source
AI summary
A periodic test signal (44) is injected into a sensor and the sensor output (46) is compared to a threshold to determined whether the sensor is functioning properly.