Tolerance Evaluation Using Boundary Point Extraction
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Solution Overview
Problem
Conventional data reduction methods for metrology, such as averaging techniques, fail to accurately preserve surface information for tolerance compliance evaluations, leading to potential acceptance of defective parts.
Innovation Solution
A method that reduces the number of measured points by identifying and representing each subset with boundary points or three-dimensional shapes that encompass all points, allowing for quick and accurate comparison to tolerance limits, using non-contact measuring techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional averaging techniques are used for data reduction, then processing speed is improved, but measurement precision deteriorates because surface information is not adequately preserved for tolerance comparison
Solution Approach 1:
The patent extracts only the essential boundary information from the complete point cloud data. By identifying and retaining only the boundary points that define the extremities of the part geometry, the method removes redundant internal points while preserving the critical surface information needed for accurate tolerance evaluation. This extraction approach maintains measurement precision while significantly reducing data volume for faster processing.
Solution Approach 2:
The patent creates a simplified copy of the original point cloud by generating a boundary representation that captures the essential geometric features. Instead of processing the entire dense point cloud, a reduced boundary point cloud is created that replicates the critical surface information needed for tolerance comparison, enabling fast processing without sacrificing accuracy.
2Measurement precision
If all measured points are retained for tolerance evaluation, then measurement precision is improved, but processing time increases making it difficult to handle large data clouds
Solution Approach 1:
The patent extracts only the essential boundary information from the complete point cloud data. By identifying and retaining only the boundary points that define the extremities of the part geometry, the method removes redundant internal points while preserving the critical surface information needed for accurate tolerance evaluation. This extraction approach maintains measurement precision while significantly reducing data volume for faster processing.
Solution Approach 2:
The patent segments the point cloud data into boundary points and internal points, then processes only the boundary points for tolerance evaluation. This segmentation separates the critical information (boundary defining the extremities) from the redundant information (internal points), enabling efficient processing while maintaining evaluation accuracy.
3Productivity
If averaging techniques are applied to reduce data points, then productivity is improved, but reliability deteriorates because extreme points determining tolerance compliance are lost
Solution Approach 1:
The patent extracts only the essential boundary information from the complete point cloud data. By identifying and retaining only the boundary points that define the extremities of the part geometry, the method removes redundant internal points while preserving the critical surface information needed for accurate tolerance evaluation. This extraction approach maintains measurement precision while significantly reducing data volume for faster processing.
Solution Approach 2:
The patent applies different treatment to different regions of the point cloud: boundary points are retained with full precision while internal points are removed. This local quality approach ensures that the critical regions (boundaries determining tolerance compliance) maintain high fidelity while non-critical regions are simplified, preserving reliability in the evaluation process.
Data Source
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AI summary
A method of determining whether a part satisfies tolerance criteria includes making a multiplicity of measurements of the part, reducing the number of measured points to a number of boundary points that define a boundary within which all measured points are encompassed and comparing the boundary to a tolerance limit of a normal surface to determine whether the part conforms to the tolerance.