3D Surface Uneven Shape Measurement via Segmentation
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Solution Overview
Problem
Existing methods for measuring the fine uneven shape on a three-dimensional curved surface, such as a gear tooth surface, fail to provide sufficient accuracy due to mechanical corrections and errors when extracting minute undulations of several μm from surfaces with height changes on the order of millimeters.
Innovation Solution
A method involving the acquisition of three-dimensional surface shape data, division into orthogonal straight lines, curve equation approximation, difference calculation, and combination of two-dimensional data to generate three-dimensional uneven shape data, allowing for high-accuracy extraction of minute undulations with amplitudes between 0.5 μm to 5 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If surface shape data is divided into multiple segments to approximate geometric shape, then the measurement process becomes feasible, but measurement precision deteriorates due to increased error when extracting uneven shape components
Solution Approach 1:
The patent divides the three-dimensional curved surface into multiple two-dimensional divided portions using straight lines orthogonal to a dividing direction. This segmentation enables processing of large curved surfaces while maintaining accuracy by treating each small portion independently with its own curve equation approximation, thereby reducing cumulative errors.
Solution Approach 2:
The patent extracts only the uneven shape component by calculating the difference between actual surface data and the approximated curve equation for each divided portion. This extraction isolates the fine unevenness (several μm) from the overall curved surface geometry, eliminating errors introduced by segmenting the large-scale surface shape.
2Ease of manufacture
If mechanical correction is used with a reference member, then the measurement setup is established, but measurement precision remains insufficient for extracting fine uneven shapes
Solution Approach 1:
The patent replaces mechanical correction methods with a computational approach. Instead of using physical reference members for mechanical alignment and correction, the system acquires three-dimensional surface shape data and uses mathematical curve equations to approximate and subtract the overall surface geometry, thereby extracting fine unevenness with higher precision.
3Shape
If the entire three-dimensional curved surface is processed as a whole, then the overall shape is captured, but fine uneven shapes are lost due to the large change in height
Solution Approach 1:
The patent segments the three-dimensional curved surface into multiple two-dimensional divided portions. By processing each small portion independently with its own curve equation, the method captures the overall shape through aggregation of local approximations while simultaneously revealing fine unevenness that would be lost in a whole-surface analysis.
Solution Approach 2:
The patent transitions from processing the entire three-dimensional surface as a single entity to dividing it into multiple two-dimensional portions. This dimensional reduction for local processing enables precise capture of fine unevenness in each segment, while the collection of all segments reconstructs the overall three-dimensional shape.
Data Source
AI summary
A method of measuring an uneven shape on a three-dimensional curved surface for measuring an uneven shape present on a three-dimensional curved surface of a measurement object and finer than the three-dimensional curved surface, the method comprising: a surface shape data acquiring step of acquiring three-dimensional surface shape data representative of a surface shape of the measurement object; a dividing step of extracting data of a divided portion representative of a surface contour shape of the divided portion from the three-dimensional surface shape data, for each of the divided portions acquired by dividing a surface of the measurement object in a certain dividing direction at regular intervals by a multiplicity of straight lines orthogonal to the dividing direction; a curve equation setting step of obtaining a curve equation approximating the entire area of the surface contour shape represented by the data of the divided portion for each of the divided portions; a difference calculation step of calculating a difference between the data of the divided portion and the curve equation for the entire area of the divided portion for each of the divided portions; and a difference combining step of combining two-dimensional data of the difference calculated for the entire area of the divided portion for each of the divided portions in the dividing direction to generate three-dimensional shape data representative of the uneven shape.