Machine Direction Sensor Cross-Direction Averaging
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Solution Overview
Problem
In continuous flat sheet processes like paper making, measuring process variables in the machine direction is challenging due to small sensor measurement windows, leading to significant cross direction variations influencing results from sensor alignment and sheet wander issues.
Innovation Solution
A machine direction sensor system with an increased cross direction sampling area, utilizing a sensor head that moves across the sheet to take multiple measurements and average them into a single reading, providing wider coverage without measuring the entire sheet width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If small sensor measurement windows are used, then sensor alignment and sheet wander issues are reduced, but cross direction variations significantly influence machine direction measurement results
Solution Approach 1:
The patent divides the measurement process into multiple discrete sampling points across the cross direction. Instead of using a single large measurement window, the system takes multiple measurements at different cross-directional positions and combines them through averaging, effectively segmenting the measurement task to achieve both precision and representativeness
Solution Approach 2:
The patent transitions from a single-point measurement approach to a multi-point approach by adding the cross-direction dimension to the measurement process. By sampling across multiple cross-directional positions and averaging, the system creates a more representative machine direction measurement that accounts for cross-directional variations
2Area of stationary object
If sensor measurement window is increased to cover more cross direction area, then cross direction averaging is improved, but sensor alignment and sheet wander issues worsen
Solution Approach 1:
Rather than using one large measurement window that would be sensitive to alignment errors, the patent segments the measurement into multiple smaller sampling points distributed across the cross direction. This segmentation maintains measurement precision while achieving cross-directional representativeness through the combination of multiple readings
Solution Approach 2:
The patent combines multiple individual measurements taken at different cross-directional positions into a single averaged reading. This merging process preserves the precision benefits of small measurement windows while achieving the representativeness of large-area sampling
3Measurement precision
If entire sheet width is measured, then most representative machine direction reading is achieved, but system complexity and cost increase significantly
Solution Approach 1:
The patent applies partial action by sampling at a sufficient number of cross-directional points to achieve representativeness without measuring the entire sheet width continuously. This selective sampling approach provides adequate representation while maintaining system simplicity and cost-effectiveness
Solution Approach 2:
The measurement system is segmented into a discrete number of sampling points across the cross direction rather than continuous measurement. This segmentation achieves representative measurements with reduced system complexity compared to full-width continuous measurement
Data Source
AI summary
Disclosed is a machine direction measurement system having an increased cross direction sampling area (significantly larger than the natural sensor measurement window) to generate a more representative and stable machine direction reading of the process. In effect, the sensor should have as wide a coverage area as possible without having to resort to the expense of measuring the entire width of the sheet.