Time-of-Flight Receiver Fault Detection via Reference Signal Evaluation
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Solution Overview
Problem
Current LIDAR systems lack an effective method to monitor and detect hardware faults and degradation in the receiver signal path, which is crucial for ensuring reliable operation and compliance with ISO26262 standards.
Innovation Solution
A time-of-flight light detection system with a plurality of circuits arranged sequentially along a signal path, including a reference signal source and an evaluation circuit to compare processed reference signals to expected results, allowing for the detection of faults and degradation in the signal channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a basic optical system check using an extra laser diode flash is performed, then the photodetector cell can be checked, but the receiver IC parameters (gain, cut-off-frequency, group delay) cannot be adequately monitored
Solution Approach 1:
The patent applies multi-functionality by using the existing signal processing infrastructure (readout elements, processing channels, evaluation circuit) to serve dual purposes: normal LIDAR operations and hardware fault monitoring. The same circuits that process reflected light signals are also used to inject, route, and evaluate reference signals for checking receiver IC parameters, eliminating the need for separate dedicated monitoring hardware.
Solution Approach 2:
The system performs self-diagnosis by using its own internal circuits to monitor its own health. The evaluation circuit compares processed reference signals against expected results using the system's native signal processing channels, allowing the receiver to detect its own faults without external testing equipment or separate monitoring systems.
2Reliability
If comprehensive monitoring of receiver IC parameters is implemented, then fault detection capability is improved, but the device complexity increases
Solution Approach 1:
The patent segments the monitoring function into discrete, manageable components: reference signal generation, signal routing through readout elements, processing through dedicated channels, and evaluation against expected results. This segmentation allows comprehensive monitoring of multiple parameters (gain, cut-off frequency, group delay) while keeping each component simple and the overall architecture modular.
Solution Approach 2:
The system performs preliminary testing by injecting reference signals through the signal path before actual LIDAR measurements are taken. This allows potential hardware faults to be detected in advance, ensuring that only functional components are used for critical measurements, thereby improving reliability without requiring complex real-time monitoring during operation.
Data Source
AI summary
A time-of-flight light detection system includes: a plurality of circuits arranged sequentially along a signal path that comprises a plurality of signal channels, the plurality of circuits including a first circuit and a second circuit arranged downstream from the first circuit; a reference signal source configured to generate a plurality of reference signals, where each of the plurality of signal channels at the first circuit receives at least one of the plurality of reference signals; and an evaluation circuit coupled to the plurality of signal channels to receive a processed reference signal from the signal path, the evaluation circuit further configured to compare the processed reference signal to a first expected result to generate a first comparison result.