Electronic Control Unit Indeterminate State Diagnosis
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Solution Overview
Problem
Existing electronic control units cannot accurately identify the three states of disconnection, earth fault, and power fault, including an indeterminate state, due to the slower operation processing device compared to the drive circuit, leading to potential misdiagnosis during self-diagnosis.
Innovation Solution
An electronic control unit is designed with a drive circuit that measures voltage or current of an electromagnetic load and stores abnormality occurrence information, allowing the operation processing section to transmit ON/OFF commands and acquire information to distinguish between normal and indeterminate states, enabling accurate abnormality diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the operation processing device performs self-diagnosis at a slower speed than the drive circuit, then the device can operate reliably, but the diagnosis accuracy deteriorates because mask signals may rise during communication, creating indeterminate states that cannot be identified
Solution Approach 1:
The patent segments the diagnostic information into two distinct types: abnormality occurrence information (indicating whether an abnormality exists) and information for distinguishing states (indicating whether the system is in a normal state, abnormal state, or indeterminate state). This segmentation allows the operation processing device to separately evaluate and identify the indeterminate state, thereby improving diagnosis accuracy without compromising operational reliability.
Solution Approach 2:
The drive circuit performs preliminary diagnostic processing before communicating with the operation processing device. It pre-evaluates the abnormality status and prepares both the abnormality occurrence information and the state distinction information in advance. This preliminary action ensures that when communication occurs, the operation processing device receives complete diagnostic data, eliminating the indeterminate state identification problem caused by slower processing speeds.
2Reliability
If the drive circuit performs comprehensive abnormality detection, then the diagnosis coverage is improved, but the device complexity increases due to the need for additional measurement and storage functions
Solution Approach 1:
The drive circuit is designed with multi-functionality, combining electromagnetic load driving, voltage/current measurement, abnormality detection, and state distinction evaluation within a single integrated circuit. By making the drive circuit universal and capable of performing multiple functions, the patent avoids the need for separate dedicated diagnostic circuits, thereby improving diagnosis coverage while controlling device complexity.
Solution Approach 2:
The patent merges the diagnostic functions with the drive circuit itself. The measurement unit, abnormality detection logic, and state evaluation capabilities are all integrated into the drive circuit that already controls the electromagnetic load. This merging approach eliminates the need for separate diagnostic hardware, reducing overall system complexity while achieving comprehensive abnormality detection.
Data Source
AI summary
An electronic control unit having a self-diagnosis function is realized in which an operation processing section is capable of identifying not only the presence or absence of the occurrence of NG of disconnection, an earth fault, and a power fault, but also three states of NG, OK, and indetermination. Therefore, when a diagnosis opportunity is present, a mask signal maintains a state of Not Mask even if the mask signal is subsequently brought into a mask state. When an operation processing device requests a drive circuit for communication therewith, the mask signal is set to the state of Mask, and information stored in a register is cleared. Further, when the mask signal is in the state of Mask when the operation processing device performs communication with the drive circuit, the operation processing device is capable of identifying that an indeterminate state free of the opportunity of the diagnosis is present.