CAD Bump Recognition via Shortest Boundary Perimeter
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Solution Overview
Problem
Existing CAD systems face inefficiencies and ergonomics issues in recognizing and selecting faces representing bumps in mechanical parts, particularly in open B-reps where the concepts of protrusion and depression are visually ambiguous.
Innovation Solution
A computer-implemented method that displays a B-rep, allowing users to select one face, and automatically recognizes a set of faces representing a bump by determining both depression and protrusion sets, selecting the one with the shortest boundary curve perimeter, thereby simplifying the recognition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If users manually select all faces representing a bump in the B-rep, then complete bump recognition is achieved, but the operation time and user effort increase significantly
Solution Approach 1:
The system performs preliminary classification of faces into depression-set and protrusion-set based on geometric criteria (convexity/concavity of edges) before the user makes their final selection. This preliminary action reduces the user's workload by pre-organizing the selection task into manageable groups, allowing users to simply choose between the two classified sets rather than manually evaluating each face individually.
Solution Approach 2:
The system automatically computes the boundary curve perimeters and identifies which set (depression or protrusion) has the shorter boundary, then presents this information to the user for confirmation. The system serves itself by performing the complex geometric analysis and selection logic, requiring minimal user intervention beyond confirming the visually obvious choice.
2Ease of operation
If the system automatically recognizes bumps without user selection, then ergonomics improve, but recognition accuracy may deteriorate due to ambiguity between protrusions and depressions
Solution Approach 1:
The system provides visual feedback by displaying the two classified sets (depression-set and protrusion-set) to the user and allowing them to confirm their choice. This feedback loop ensures that automatic recognition does not sacrifice accuracy, as the user can verify that the system's classification matches their intent before finalizing the bump recognition.
Solution Approach 2:
The system performs more analysis than strictly necessary by computing both depression-set and protrusion-set classifications and their boundary perimeters, then uses this excessive information to present the user with a simplified choice. This partial action approach ensures accuracy by over-analyzing the geometry, then using the results to guide minimal user interaction.
3Manufacturing precision
If the system distinguishes between protrusions and depressions, then geometric precision is maintained, but the complexity of the recognition process increases
Solution Approach 1:
The system segments the bump recognition process into distinct phases: (1) classifying each face as belonging to the depression-set or protrusion-set based on edge convexity, (2) computing boundary curves for each set, (3) comparing boundary perimeters, and (4) presenting the result to the user. This segmentation of the complex recognition process into manageable steps maintains geometric precision while reducing overall process complexity.
Solution Approach 2:
The system performs partial classification by grouping faces into two sets based on geometric criteria, then performs excessive analysis by computing boundary perimeters for both sets. This approach maintains geometric precision through thorough analysis while managing complexity by organizing the work into systematic, repeatable steps that can be automated.
Data Source
AI summary
A computer-implemented method for designing, with a CAD system, a 3D modeled object representing a mechanical part. The method includes displaying a B-rep having faces and edges and representing at least a part of the mechanical part, selecting, by graphical user interaction, at least one face of the B-rep, and, automatically by the CAD system, recognizing a set of faces including the at least one face and representing a bump. The recognizing includes determining a first set of faces representing a depression and a second set of faces representing a protrusion, and selecting, among the first set of faces and the second set of faces, a set of faces having a shortest boundary curve perimeter and being different from both the selected at least one face and the B-rep. The first set of faces and the second set of faces both comprise the at least one face.