CAD Sketch Constraint Generation for Solver-Convergent Dimensioning

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Solution Overview

Problem

Conventional constraint solvers in CAD software often result in over-constrained or under-constrained conditions, leading to solver failures and unpredictable constraint sets, while machine learning models struggle with training data limitations and generate incorrect constraints due to hidden correlations and unlabeled feature variants.

Innovation Solution

A computer-implemented method for training a constraint generation model using a tokenization and embedding-based architecture, combined with preference-based optimization and reinforcement learning, to generate accurate and convergent constraint sequences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional constraint solvers insert every identifiable constraint or dimension, then constraint completeness is improved, but solver reliability deteriorates due to over-constrained conditions

Engineering Contradiction:
Improveconstraint completenessVSAvoidsolver reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The system implements feedback mechanisms where the constraint solver communicates with the user interface to report over-constrained or under-constrained conditions. Users receive feedback about constraint status and can manually adjust or remove inappropriate constraints, creating a closed-loop system that adapts to design intentions and resolves contradictions between completeness and reliability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically changes constraint parameters based on detected conditions. When over-constrained situations are identified, the system can selectively disable or modify specific constraints while maintaining others, allowing flexible adaptation to different design scenarios and preserving both completeness and reliability through parameter adjustment.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conventional constraint solvers use heuristic techniques to limit search space, then solver reliability is improved, but constraint accuracy deteriorates due to guesswork

Engineering Contradiction:
Improvesolver reliabilityVSAvoidconstraint accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The system introduces an intermediary layer between the sketch parsing and constraint generation processes. This intermediary analyzes geometric relationships more thoroughly before constraint creation, acting as a mediator that filters out inaccurate heuristics while preserving reliable constraint candidates, thereby improving overall constraint accuracy without sacrificing solver reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system replaces traditional mechanical constraint solving with a hybrid approach that incorporates machine learning models trained on design patterns. This substitution enables the system to learn from historical data what constraints are typically appropriate, replacing guesswork-based heuristics with data-driven accuracy while maintaining reliability through validated constraint generation processes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Quantity of substance

If machine learning models rely on constrained or sparsely labeled training examples, then training data requirements are reduced, but constraint generation accuracy deteriorates due to hidden correlations and unlabeled feature variants

Engineering Contradiction:
Improvetraining data quantityVSAvoidconstraint generation accuracy
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The system segments the constraint generation task into multiple components: geometric relationship detection, constraint type classification, and constraint validity verification. This segmentation allows the machine learning model to focus on pattern recognition from available data while separate modules handle the complexity of hidden correlations and feature variants, improving accuracy without requiring proportionally more training data.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs preliminary actions by pre-processing sketch data to identify and label common geometric patterns and relationships before they are used for constraint generation. This preliminary labeling of feature variants and correlation patterns enables the machine learning model to learn from richer data representations, improving constraint generation accuracy while still working with limited training examples.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS20260080127A1Generative constraining and dimensioning of computer-aided design sketches
Publication Date: 2026.03.19 AUTODESK INC
  • US20260080127A1 patent drawing
  • US20260080127A1 patent drawing
  • US20260080127A1 patent drawing

AI summary

Generative constraining and dimensioning of CAD sketches includes receiving training data comprising a plurality of training data elements, each training data element comprising an input sketch and a ground truth constraint sequence, selecting a first training data element from the plurality of training data elements, generating a variable length prompt from the first training data element, presenting the variable length prompt to a constraint generation model to generate a first constraint sequence, generating a loss based on the first constraint sequence, and updating the constraint generation model based on the loss.