Imaging Subsystem Self-Test via Software-Based Fault Detection
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Solution Overview
Problem
Advanced Driver Assistance Systems (ADAS) face challenges in ensuring the functional safety of imaging subsystems, particularly in detecting intermittent and latent faults, which are not effectively addressed by existing hardware-based self-tests, and require a comprehensive self-test strategy to guarantee safe operation throughout the lifecycle.
Innovation Solution
Implementing a software-based self-test method for imaging subsystems in camera-based ADAS, involving periodic execution of test software instructions on a system-on-a-chip (SoC) processor, processing reference image data to verify correct operation, and using cyclic redundancy check (CRC) computations to detect faults, thereby identifying both intermittent and permanent faults during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hardware-based self-tests are used, then device complexity is reduced, but reliability is insufficient for detecting intermittent and latent faults
Solution Approach 1:
The patent replaces hardware-based self-test mechanisms with software-based self-test instructions that execute on the processor. This substitution allows for more sophisticated fault detection algorithms (including intermittent and latent fault detection) without adding physical test hardware, thereby improving reliability while avoiding increased device complexity.
Solution Approach 2:
The processor is designed to execute multiple functions: normal ADAS processing and self-test operations. By making the processor universal, the system can perform both image processing and self-testing using the same hardware resources, eliminating the need for separate dedicated test hardware and maintaining low device complexity while achieving high reliability.
2Reliability
If software-based self-tests are implemented, then reliability improves for detecting intermittent faults, but device complexity increases due to additional processing requirements
Solution Approach 1:
The self-test instructions are executed periodically at predetermined intervals rather than continuously. This periodic execution reduces the processing burden and complexity while still maintaining the ability to detect intermittent faults that may occur between test cycles. The interval-based approach balances reliability improvement with acceptable processing complexity.
Solution Approach 2:
The system performs preliminary self-test checks during normal operation by executing test instructions that verify processor functionality before critical failures occur. This preliminary action allows the system to detect potential issues early without requiring complex real-time monitoring mechanisms, thus improving reliability while keeping processing complexity manageable.
3Reliability
If comprehensive self-test strategy is implemented throughout lifecycle, then functional safety is improved, but loss of time increases due to periodic testing
Solution Approach 1:
The system implements partial self-testing by executing only critical self-test instructions periodically rather than performing exhaustive tests at all times. This approach provides sufficient functional safety coverage for the most important safety-critical functions while minimizing the time lost to testing. The selective execution of essential test routines balances safety requirements with operational time constraints.
Data Source
AI summary
A method for testing an imaging subsystem of a system-on-a-chip (SOC) is provided that includes executing imaging subsystem test software instructions periodically on a processor of the SOC, receiving reference image data in the imaging subsystem responsive to the executing of the test software instructions, performing image signal processing on the reference image data by the imaging subsystem to generate processed reference image data, and using the processed reference image data by the test software instructions to verify whether or not the imaging subsystem is operating correctly.