Meter Secondary Offset Calibration for Piecewise Linear Error Correction
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Solution Overview
Problem
Existing piecewise linear calibration methods for meters fail to adequately correct measurement errors within predefined values over a measurement range, limiting the accuracy of fluid flow meters, and existing methods incur additional cost and complexity in rebuilding or removing meters that cannot achieve desired accuracy.
Innovation Solution
A secondary offset calibration method is applied, which defines regions based on initial calibration points and selects recalibration points within these regions to adjust the B value, centering measurement accuracy around zero and reducing maximum errors, thereby improving overall meter accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piecewise linear calibration is applied to the meter, then calibration factors can be calculated at calibration points to adjust error values to 0%, but measurement errors cannot be adequately corrected to be within predefined values over the entire measurement range
Solution Approach 1:
The measurement range is divided into multiple regions based on calibration points, and a secondary offset calibration is performed within each region. This segmentation allows for more precise error correction in each sub-region while maintaining the overall piecewise linear calibration structure.
Solution Approach 2:
A secondary offset calibration parameter is introduced to adjust the calibration curve within each region. This additional parameter enables fine-tuning of measurement accuracy within predefined error limits without requiring a complete recalibration or increasing the number of calibration points.
2Measurement precision
If more calibration points are utilized to improve measurement accuracy, then measurement errors can be reduced, but memory size and meter configuration limitations prevent utilizing additional calibration points
Solution Approach 1:
Instead of increasing the number of calibration points (which would require more memory and configuration space), a secondary offset parameter is introduced to each existing calibration region. This parameter change achieves improved accuracy without increasing device complexity or memory requirements.
Solution Approach 2:
The secondary offset calibration applies a partial correction within each existing calibration region rather than requiring a complete recalibration with additional points. This partial action achieves sufficient accuracy improvement without the resource cost of full recalibration.
3Measurement precision
If piecewise linear calibration is repeated to further improve accuracy, then measurement errors can be adjusted, but errors are already at 0% at calibration points so repeating calibration would not further improve accuracy
Solution Approach 1:
The secondary offset calibration focuses on local error correction within each calibration region rather than repeating the global piecewise linear calibration. This local quality improvement targets specific error patterns between calibration points without requiring a complete recalibration process.
Solution Approach 2:
The calibration process is segmented into two distinct stages: the initial piecewise linear calibration that sets calibration factors at discrete points, and the secondary offset calibration that fine-tunes accuracy within each region. This segmentation allows each stage to address specific error types efficiently.
Data Source
AI summary
A method and a system for improving measurement accuracy of a meter previously calibrated are provided. A region over a measurement range of the meter is defined based at least in part on a plurality of calibration points utilized to previously calibrate the meter, where the region includes a first calibration constant and a second calibration constant. A quantity output of the meter is recalibrated by: selecting one or more recalibration points within the region; measuring one or more corresponding error factors at the one or more recalibration points; and determining a revised second calibration constant based on the one or more corresponding error factors and the second calibration constant. The recalibrated quantity output of the meter is then generated based on a measured quantity output by the meter, the first calibration constant, and the revised second calibration constant.