Qunfen Qi

Modeling the integration between specifications and verification for cylindricity based on category theory

Geometrical product specifications (GPS) is a standard system defined by ISO/TC213 which covers the standardization for micro- and macro-geometry specifications to make it suitable for the requirements of modern technologies. In addition, it integrates specifications and verification to make geometrical specifications more unambiguous and unique. Data modeling is a primary task in building an integrated information system for the application of geometrical characteristics consistent with the GPS standard system. It is feasible to extend this data modeling method to the whole GPS information system. This paper presents data modeling for the integration between specifications and verification for cylindricity consistent with GPS based on the category theory. The categorical data modeling method represents and stores all the elements and the relationships between them concerning the specifications and the verification process for cylindricity by categories, objects and morphisms; the established categories can be extended flexibly; the relationships between the objects were refined by pull back structures; and the manipulations of the model, such as query and the closure of query, are realized successfully by functor transforms in category theory.

Design and implementation of an integrated surface texture information system for design, manufacture and measurement☆

Abstract The optimized design and reliable measurement of surface texture are essential to guarantee the functional performance of a geometric product. Current support tools are however often limited in functionality, integrity and efficiency. In this paper, an integrated surface texture information system for design, manufacture and measurement, called “CatSurf”, has been designed and developed, which aims to facilitate rapid and flexible manufacturing requirements. A category theory based knowledge acquisition and knowledge representation mechanism has been devised to retrieve and organize knowledge from various Geometrical Product Specifications (GPS) documents in surface texture. Two modules (for profile and areal surface texture) each with five components are developed in the CatSurf. It also focuses on integrating the surface texture information into a Computer-aided Technology (CAx) framework. Two test cases demonstrate design process of specifications for the profile and areal surface texture in AutoCAD and SolidWorks environments respectively.

Status, comparison, and issues of CAD model data exchange methods based on standardized neutral files and OWL file

Exchanging CAD model data among heterogeneous CAD systems is indispensable for collaborative product development. Currently, the industry mainly uses the standardized neutral files based methods to implement such exchange. While at the same time, the application of Web Ontology Language (OWL) file and underlying Semantic Web technologies in CAD model data exchange is gaining importance and popularity within the academia. The coexistence of different types of methods has generated a series of controversies and questions within the industry and the academia. Yet, can the neutral files based exchange methods completely implement model data exchange among heterogeneous CAD systems? What challenges have been addressed to date by the developed CAD model data exchange standards? Why OWL has been introduced to CAD model data exchange? Does CAD model data exchange really need OWL? Are there any issues in existing neutral files based exchange methods and OWL file based exchange methods need to be addressed in future studies? This paper proposes to conduct a study of the standardized neutral files based exchange methods and OWL file based exchange methods. An in-depth analysis of the widely used STandard for the Exchange of Product model data (STEP) method and the newly emerging OWL methods is firstly provided. Then the paper makes a detailed comparison between these two types of methods based on this analysis. Finally, some issues in the two types of methods that need to be addressed in the future are discussed

Towards an ontology-supported case-based reasoning approach for computer-aided tolerance specification

Abstract In this paper, an ontology-supported case-based reasoning approach for computer-aided tolerance specification is proposed. This approach firstly considers the past tolerance specification problems and their schemes as previous cases and the new tolerance specification problems as target cases and uses an ontology to represent previous and target cases. Then certain ontology-based similarity measure is used to assess the similarity between the toleranced features of target and previous cases, the similarity between the part features of target and previous cases, and the similarity between the topological relations of target and previous cases. Based on these similarities, an ontology-based similarity measure for computing the similarity between target and previous cases is designed, and an algorithm for establishing such similarity measure with high accuracy and retrieving similar previous cases for a target case with this similarity measure is presented. This algorithm shows how to linearly combine the similarity of toleranced features, the similarity of part features, and the similarity of topological relations to assess the similarity between target and previous cases to implement retrieval of previous cases under the prerequisite of ensuring the highest accuracy of the similarity measure. The paper also reports a prototype implementation of the proposed approach, provides an example to illustrate how the approach works, and evaluates the approach via theoretical and experimental comparisons.

Selecting a semantic similarity measure for concepts in two different CAD model data ontologies

Semantic similarity measure technology based approach is one of the most popular approaches aiming at implementing semantic mapping between two different CAD model data ontologies. The most important problem in this approach is how to measure the semantic similarities of concepts between two different ontologies. A number of measure methods focusing on this problem have been presented in recent years. Each method can work well between its specific ontologies. But it is unclear how accurate the measured semantic similarities in these methods are. Moreover, there is yet no evidence that any of the methods presented how to select a measure with high similarity calculation accuracy. To compensate for such deficiencies, this paper proposes a method for selecting a semantic similarity measure with high similarity calculation accuracy for concepts in two different CAD model data ontologies. In this method, the similarity calculation accuracy of each candidate measure is quantified using Pearson correlation coefficient or residual sum of squares. The measure with high similarity calculation accuracy is selected through a comparison of the Pearson correlation coefficients or the residual sums of squares of all candidate measures. The paper also reports an implementation of the proposed method, provides an example to show how the method works, and evaluates the method by theoretical and experimental comparisons. The evaluation result suggests that the measure selected by the proposed method has good human correlation and high similarity calculation accuracy.

A Surface Texture Information System Integrated with AutoCAD for Next Generation GPS

To meet the requirements of next generation Geometrical Product Specification and Verification (GPS), a surface texture information system integrated with AutoCAD is developed. The information system mainly consists of three parts: a surface texture database containing large amount of surface texture specification information, inference algorithms and interfaces with AutoCAD, so that unambiguous, explicit and complete specification for design, manufacture and verification of surface texture can be provided in AutoCAD for function assurance.

Categorical data model for Cylindricity Consistent with Geometrical Product Specifications Standard System

Geometrical Product Specifications is an international standard system regarding standardization of dimensional, tolerancing, surface texture and related metrological principles and practices in the charge of ISO/TC213. Integrated information system is necessary to encapsulate the knowledge in GPS to extend its application in digital manufacturing. Establishing a suitable data structure for GPS data is one of the main works in building the integrated information system. This paper is focused on cylindricity and the main points are as follows: proposes the complete verification operator and the complete drawing indication for cylindricity consistent with GPS standard system; models the inter/intra relationships between the elements of operations involved in cylindricity and integrates them by category theory; solves the storage format and closure of query for the categorical data model by the pull-back structure and functor transform in category theory respectively.