CAD Constraint Graph Depth Analysis for Cycle Resolution

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Solution Overview

Problem

Current CAD systems face challenges in efficiently modifying industrial product designs due to constraint orientation issues, which complicate understanding the modification intent and can lead to cycles of dependencies, hindering fluent deformation of geometries.

Innovation Solution

A method that models constraints between geometries as a graph with nodes and edges, computes depth values to identify and reverse antagonistic constraints, allowing modifications to propagate according to design intent while preserving reference elements and restoring original orientations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If constraints are oriented at creation step to ensure predictable system behavior, then usability is improved, but modification becomes difficult because the orientation is not visible and the master/slave relationship cannot be easily understood

Engineering Contradiction:
ImproveusabilityVSAvoidmodification complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary mechanism (constraint orientation detection and automatic reversal system) that mediates between the user's modification intent and the constraint network. When a user attempts to modify a slave geometry, the system automatically detects the orientation issue and reverses the constraint orientation, allowing the modification to proceed without manual intervention while maintaining system predictability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The constraint network becomes self-service by automatically detecting and correcting its own orientation issues. When a modification operation is attempted on a slave geometry, the system automatically reverses the constraint orientation to make the geometry modifiable, eliminating the need for manual orientation management and making the system adaptive to user intent

Inventive Principle:
Principle #25Self-service

2Stability of the object's composition

If the CAD system maintains fixed constraint orientations to ensure predictable behavior, then system stability is improved, but productivity decreases because designers must manually reverse constraints and iterate changes

Engineering Contradiction:
Improvesystem stabilityVSAvoiddesign productivity
Core Design Contradiction:
Stability of the object's compositionVSProductivity

Solution Approach 1:

The patent makes the constraint network dynamic by allowing automatic reversal of constraint orientations during modification operations. The system adapts the constraint orientation based on the user's modification intent, transforming from a static fixed-orientation system to a dynamic system that automatically adjusts to user needs, thereby improving productivity while maintaining stability through automated control

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements feedback by detecting when a modification operation is attempted on a slave geometry and automatically reversing the constraint orientation in response. This closed-loop feedback mechanism allows the system to maintain stability through automated correction while eliminating manual iteration, thereby improving productivity

Inventive Principle:
Principle #23Feedback

3Adaptability or versatility

If designers are allowed to create cycles of oriented constraints for flexible design, then design versatility is improved, but convergence issues arise because the solution computation requires iterative processes

Engineering Contradiction:
Improvedesign versatilityVSAvoidsolution convergence
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by automatically reversing antagonistic constraints before the modification computation is performed. By proactively detecting and correcting constraint orientations that would create cycles or convergence issues, the system prepares the constraint network in advance, allowing flexible design while ensuring reliable solution convergence

Inventive Principle:
Principle #10Preliminary action

4Device complexity

If the system requires iterative modification of master elements to achieve design intent, then constraint orientation control is maintained, but time is lost because the designer must repeatedly try modifications to understand the constraint orientation

Engineering Contradiction:
Improveconstraint controlVSAvoidmodification time
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The constraint network becomes self-service by automatically detecting when a modification is attempted on a slave geometry and reversing the orientation to accommodate the user's intent. This eliminates the need for iterative trial-and-error modifications, allowing designers to immediately implement their intended changes without repeatedly testing to understand constraint orientations, thereby significantly reducing modification time

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2921978B1Designing industrial products by using geometries connected by geometrical constraints
Publication Date: 2021.09.29 DASSAULT SYSTEMES SA
  • EP2921978B1 patent drawingFigure 1~2
  • EP2921978B1 patent drawingFigure 3~5
  • EP2921978B1 patent drawingFigure 6~7

AI summary

The invention notably relates to a computer-implemented method of design of an industrial product wherein constraints between geometries of the industrial product are modeled with a graph of constraints comprising nodes and edges, a node representing a geometry and an edge representing a constraint between two geometries. The method comprising the steps of selecting at least one geometry of the product; computing a depth value of each node of the graph from a node representing the at least one selected geometry; identifying antagonistic constraint(s) in the graph, an antagonistic constraint being represented by an oriented edge wherein the depth value of the start node is larger to the depth value of the end node; reversing the identified antagonistic constraint(s); modifying the at least one selected geometry;