Context-Free Grammar CAD Design Priority Ordering
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Solution Overview
Problem
Existing CAD systems face challenges in managing complex design modifications, particularly when design features overlap, leading to difficulties in maintaining geometry computation and requiring significant user expertise, which limits collaborative design and increases design time and costs.
Innovation Solution
A computer-implemented method using a context-free grammar with a seed structure and set of rules allows for flexible priority ordering of design features, enabling declarative design and high user handiness by modifying the priority order between design features, thus maintaining the advantages of history-based systems without the limitations of fixed seed structure capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If history-based CAD systems are used to maintain design feature order, then design modifications can be tracked, but the resulting geometry becomes dependent on feature creation order which complicates collaborative design
Solution Approach 1:
The patent inverts the traditional history-based approach by using a declarative grammar-based system where the final geometry is determined by grammatical rules rather than creation order. Instead of tracking feature history, the system evaluates design features against a context-free grammar that defines valid part structures, allowing collaborative design without order dependency while maintaining design integrity through grammatical validation.
2Device complexity
If fixed seed structure capabilities are used in grammar-based systems, then geometry computation is simplified, but user handiness and flexibility are reduced
Solution Approach 1:
The patent implements a dynamic grammar-based system where the seed structure is not fixed but can be adapted through grammatical rules. The context-free grammar allows the system to dynamically evaluate and transform design features based on defined production rules, providing both computational simplicity through structured evaluation and user flexibility through rule-based customization of part designs.
3Shape
If design features are created in a specific order in history-based systems, then the physical structure of the part is determined, but modifying existing designs requires understanding and maintaining that specific order which increases learning time
Solution Approach 1:
The patent replaces the mechanical history-based system with a declarative grammar-based system. Instead of requiring users to understand and maintain feature creation order (mechanical process), the system uses grammatical rules to automatically determine the correct evaluation order and physical structure. This substitution eliminates the need for users to learn complex feature sequencing while still producing accurate part geometries.
4Manufacturing precision
If overlapping design features are managed in traditional CAD systems, then geometry computation can be maintained, but significant user expertise is required which limits collaborative design
Solution Approach 1:
The patent introduces a grammar-based evaluation system as an intermediary between design features and geometry computation. This intermediary automatically handles the complex logic of overlapping features by evaluating them against grammatical rules, eliminating the need for users to possess expert knowledge of feature interaction while maintaining precise geometry computation through systematic rule-based evaluation.
Data Source
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AI summary
The invention relates to a computer implemented method for designing a part modeled by using: - a seed structure of a context-free grammar, - a set of rules of the grammar, - at least two design features, each design feature being defined by at least one rule of the set, - a priority order between the design features determined by the seed structure and the set of rules. The method comprises the steps of: - displaying a representation of the part in a graphical user interface according to the priority order, - modifying the priority order between said two design features by modifying the set of rules, - displaying a representation of the part according to the modified priority order.