Torque Sensor Offset Correction for Aging Variations
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Solution Overview
Problem
Existing torque sensors, such as those in electric power steering devices, fail to accurately correct detection values due to aged deterioration and accuracy variations of parts, leading to potential errors in steering torque measurement.
Innovation Solution
A sensor device with a controller that calculates offset and gain correction values based on detection values, accounting for aged deterioration and accuracy variations, allowing for precise correction of detection values and improved steering torque measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature-based correction is applied to torque signals, then temperature-related errors are reduced, but aged deterioration and accuracy variation of parts are not addressed
Solution Approach 1:
The patent extends correction from single temperature parameter to multiple parameters including offset and gain values that account for aged deterioration and accuracy variation. The controller calculates corrected torque signals by applying both offset correction and gain correction based on stored correction values, thereby addressing comprehensive error sources beyond temperature alone.
2Device complexity
If simple temperature correction is used, then correction process is simple, but comprehensive accuracy including aged deterioration is not achieved
Solution Approach 1:
The patent performs preliminary calculation and storage of offset correction values and gain correction values under various conditions (temperatures, ages). These pre-calculated correction values are stored in memory and retrieved during operation, allowing the system to apply comprehensive corrections without real-time complex calculations, thus balancing accuracy with computational efficiency.
Data Source
AI summary
A sensor device includes a plurality of sensor elements and an output circuit in one sensor part, and a correction value calculator in an ECU, which obtains output signals from the sensor part and calculates an offset correction value based on a plurality of signal values that correspond to a detection value when a calculability condition is satisfied. The ECU also includes a control calculator that performs a calculation based on the corrected signal values that have been corrected by the offset correction value. Therefore, the offset correction value is calculated in view of an aging and an accuracy variation of the components used in the sensor device. In such manner, the detection value is appropriately corrected for the calculation.