Vehicle OBD Fault Isolation Using Diagnostic Estimator Ratios
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Solution Overview
Problem
Current on-board diagnostic (OBD) systems often generate broad, system-level fault codes, making it difficult for technicians to identify the specific failure mode causing performance loss in vehicle systems, as they typically require separate fault isolation mechanisms to pinpoint the faulty component.
Innovation Solution
A system that includes processing circuits and memory devices configured to store a fault isolation table with a relationship matrix of diagnostic estimators and failure modes, allowing for the acquisition and comparison of OBD capability data from multiple monitors to isolate faulty components within the vehicle system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If system-level fault codes are used to alert drivers and technicians to issues, then the coverage of fault detection is improved, but the precision of fault identification deteriorates
Solution Approach 1:
The patent segments the vehicle system into multiple control volumes, each monitored by specific diagnostic estimators. Instead of providing a single system-level fault code, the system divides the diagnostic space into smaller regions (control volumes) that can be independently analyzed. This segmentation allows technicians to identify which specific control volume contains the fault, thereby improving fault identification precision while maintaining comprehensive coverage through the complete set of control volumes.
2Reliability
If multiple diagnostic monitors are deployed to monitor different portions of the vehicle system, then the coverage of fault detection is improved, but the complexity of fault isolation increases
Solution Approach 1:
The patent introduces control volumes as intermediary structures that organize the relationship between diagnostic estimators and failure modes. Each control volume acts as a mediator that groups specific estimators and failure modes together. This intermediary structure simplifies fault isolation by providing a hierarchical framework: first identify which control volume contains the fault, then use the pre-defined relationships within that control volume to pinpoint the specific failure mode, reducing the complexity compared to analyzing all monitors simultaneously.
3Ease of manufacture
If broad system-level fault codes are generated, then the ease of implementation is improved, but the time required for fault isolation increases
Solution Approach 1:
The patent performs preliminary action by pre-defining control volumes and their associated diagnostic estimators and failure modes before actual fault occurrence. The relationship between estimators, control volumes, and failure modes is established in advance through system design and configuration. When a fault occurs, technicians can immediately query which control volume is affected and what failure modes are possible within that volume, eliminating the need for time-consuming trial-and-error diagnostic procedures and significantly reducing fault isolation time.
Data Source
AI summary
A system is configured to store a relationship data set of a plurality of diagnostic estimators and a plurality of failure modes, each failure mode represents a type of failure that can occur with a sensor or a vehicle component of a vehicle system, each diagnostic estimator is associated with a respective subset of the failure modes, each subset defines a control space within the vehicle system that contains at least one of (i) one or more sensors or (ii) one or more vehicle components. The system is configured to store a healthy diagnostic vector regarding nominal operational parameters of the vehicle system; acquire diagnostic information regarding current operational parameters of the vehicle system to generate an error diagnostic vector; apply the error diagnostic vector to the healthy diagnostic vector to generate a ratio diagnostic vector; and apply the ratio diagnostic vector to generate a value for each failure mode.