Fault Detection Circuit Design Using Three-Signal Implication Extraction
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Solution Overview
Problem
Conventional fault detection methods in in-vehicle LSI systems, such as those adhering to ISO26262 standards, face limitations in achieving sufficient diagnostic coverage for functional safety, leading to an inability to finely adjust the trade-off between area overhead and diagnostic coverage.
Innovation Solution
A method for designing a fault detection circuit that selects a fixed signal value to extract high-capability three-signal implication relationships, combining them with two-signal implication relationships to enhance fault detection capability while minimizing area overhead, by categorizing three-signal implication relationships based on their predictability from two-signal relationships and using appropriate indices for extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three-signal implication relationships are used to improve fault detection capability, then diagnostic coverage is improved, but area overhead increases significantly
Solution Approach 1:
The patent extracts and selects only the most effective three-signal implication relationships from the total possible combinations. By using selection criteria based on two-signal implication relationship results and circuit characteristics, it extracts a subset of high-value relationships rather than implementing all possible relationships, thereby reducing area overhead while maintaining diagnostic coverage.
Solution Approach 2:
The patent implements partial action by using only a portion of the total possible three-signal implication relationships. It applies excessive action to the most critical relationships while omitting less important ones, achieving sufficient diagnostic coverage without the full area cost of implementing all relationships.
2Reliability
If the number of three-signal implication relationships is increased to improve fault detection, then diagnostic coverage is improved, but the complexity of selection and implementation increases
Solution Approach 1:
The patent performs preliminary action by first identifying and analyzing two-signal implication relationships before selecting three-signal relationships. This preliminary analysis provides a foundation for making informed decisions about which three-signal relationships to implement, reducing the complexity of the selection process.
Solution Approach 2:
The patent uses feedback from two-signal implication relationship analysis to guide the selection of three-signal relationships. The results from analyzing pairs of signals provide feedback that informs which triplets of signals should be examined, creating a systematic approach that reduces selection complexity.
3Area of stationary object
If conventional fault detection methods are used, then area overhead is reduced, but diagnostic coverage is insufficient to meet functional safety standards
Solution Approach 1:
The patent merges conventional fault detection methods with implication relationship-based detection. It combines the area efficiency of conventional methods with the enhanced diagnostic coverage of implication relationships, creating a hybrid approach that achieves both goals.
Solution Approach 2:
The patent creates a composite fault detection system that integrates multiple detection techniques. It combines conventional detection methods with selected three-signal implication relationships, forming a composite approach that leverages the strengths of each method while mitigating their individual weaknesses.
Data Source
AI summary
A method for designing a fault detection circuit includes an extraction step of selecting a fixed signal value based on an index, and extracting, by using the fixed signal value selected, one or some but not all of three-signal implication relationships.