Rotation Angle Sensor Diagnosis Using Adaptive Reference Thresholds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The accuracy of failure diagnosis in rotational angle sensors is compromised due to inherent variations in generating and processing circuits, causing the sum of squares of sine and cosine wave signals to deviate from a unique value, even when the sensor operates normally.
Innovation Solution
A diagnostic apparatus and method that obtain a reference value from correlated signals output by the rotational angle sensor, allowing for failure diagnosis based on whether the numerical value falls within a predetermined range, accounting for individual and non-reproducible variations in the circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed threshold is used for failure diagnosis based on the sum of squares of sine and cosine wave signals, then the diagnosis method is simple, but the accuracy is reduced due to circuit variations
Solution Approach 1:
The patent applies preliminary action by obtaining a reference value from the rotational angle sensor during a normal operation period before actual failure diagnosis. This reference value, which reflects the actual characteristics of the sensor including circuit variations, is stored and then used as a basis for setting dynamic thresholds during subsequent failure diagnosis. This approach allows the system to account for individual circuit variations without requiring complex predetermined threshold tables, thereby improving diagnosis accuracy while maintaining relative simplicity.
2Reliability
If individual variations in circuits are considered by setting wider thresholds, then false diagnoses are reduced, but the ability to detect actual failures is diminished
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the diagnosis threshold based on the obtained reference value. Instead of using fixed or overly wide thresholds, the system calculates thresholds relative to the reference value (e.g., reference value ± margin). This allows the threshold to adapt to the specific sensor characteristics while maintaining appropriate sensitivity for detecting actual failures, thus balancing reliability and detection precision.
3Measurement precision
If a predetermined threshold table is used for different rotational angles, then diagnosis accuracy is improved, but the complexity and memory requirements increase
Solution Approach 1:
The patent extracts only the essential characteristic (reference value) from the rotational angle sensor during normal operation, rather than storing comprehensive threshold tables for different rotational angles. By obtaining a single reference value that represents the overall characteristics of the sensor including its circuit variations, the system simplifies the diagnosis mechanism while maintaining accuracy. This reference value is then used to dynamically determine appropriate thresholds during failure diagnosis, eliminating the need for complex predetermined threshold tables.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A diagnostic apparatus for a rotational angle sensor that outputs two correlated signals, corresponding to the rotational angle, obtains a reference value from the two correlated signals. Thereafter, the diagnostic apparatus for the rotational angle sensor diagnoses whether or not a failure has occurred in the rotational angle sensor based on whether or not a numerical value obtained from the two correlated signals is within a predetermined range including the reference value.