The current computer-aided technologies in design and product development, the evolution of CAD modeling, and a framework of multi-volume CADmodeling system for heterogeneous object design and fabrication are presente...The current computer-aided technologies in design and product development, the evolution of CAD modeling, and a framework of multi-volume CADmodeling system for heterogeneous object design and fabrication are presented inthis paper. The multi-volume CAD modeling system is presented based on nonmanifold topological elements. Material identifications are defined as design attributes introduced along with geometric and topological information at the designstage. Extended Euler operation and reasoning Boolean operations for merging andextraction are executed according to the associated material identifications in thedeveloped multi-volume modeling system for heterogeneous object. An applicationexample and a pseudo-processing algorithm for prototyping of heterogeneous structure through solid free-form fabrication are also described.展开更多
Cloud manufacturing is one of the three key technologies that enable intelligent manufacturing.This paper presents a novel attribute-based encryption(ABE)approach for computer-aided design(CAD)assembly models to effec...Cloud manufacturing is one of the three key technologies that enable intelligent manufacturing.This paper presents a novel attribute-based encryption(ABE)approach for computer-aided design(CAD)assembly models to effectively support hierarchical access control,integrity verification,and deformation protection for co-design scenarios in cloud manufacturing.An assembly hierarchy access tree(AHAT)is designed as the hierarchical access structure.Attribute-related ciphertext elements,which are contained in an assembly ciphertext(ACT)file,are adapted for content keys decryption instead of CAD component files.We modify the original Merkle tree(MT)and reconstruct an assembly MT.The proposed ABE framework has the ability to combine the deformation protection method with a content privacy of CAD models.The proposed encryption scheme is demonstrated to be secure under the standard assumption.Experimental simulation on typical CAD assembly models demonstrates that the proposed approach is feasible in applications.展开更多
CAD model retrieval based on functional semantics is more significant than content-based 3D model retrieval during the mechanical conceptual design phase. However, relevant research is still not fully discussed. There...CAD model retrieval based on functional semantics is more significant than content-based 3D model retrieval during the mechanical conceptual design phase. However, relevant research is still not fully discussed. Therefore, a functional semantic-based CAD model annotation and retrieval method is proposed to support mechanical conceptual design and design reuse, inspire designer creativity through existing CAD models, shorten design cycle, and reduce costs. Firstly, the CAD model functional semantic ontology is constructed to formally represent the functional semantics of CAD models and describe the mechanical conceptual design space comprehensively and consistently. Secondly, an approach to represent CAD models as attributed adjacency graphs(AAG) is proposed. In this method, the geometry and topology data are extracted from STEP models. On the basis of AAG, the functional semantics of CAD models are annotated semi-automatically by matching CAD models that contain the partial features of which functional semantics have been annotated manually, thereby constructing CAD Model Repository that supports model retrieval based on functional semantics. Thirdly, a CAD model retrieval algorithm that supports multi-function extended retrieval is proposed to explore more potential creative design knowledge in the semantic level. Finally, a prototype system, called Functional Semantic-based CAD Model Annotation and Retrieval System(FSMARS), is implemented. A case demonstrates that FSMARS can successfully botain multiple potential CAD models that conform to the desired function. The proposed research addresses actual needs and presents a new way to acquire CAD models in the mechanical conceptual design phase.展开更多
An algorithm for compensating the varying section contour within the extent of each layer thickness is proposed to improve the rapid prototyping part’s shape and size precision.
Based on the principles of differential geometry and kinematics, a mathematical model is developed to describe the grinding wheel axial cross-section with the radial cross-section of the flute in a given drill under t...Based on the principles of differential geometry and kinematics, a mathematical model is developed to describe the grinding wheel axial cross-section with the radial cross-section of the flute in a given drill under the basic engagement condition between the generating flute and the generated grinding wheel (or disk milling tool). The mathematical model is good for the flute in the radial cross-section consisting of three arcs. Furthermore, a CAD system is also developed to represent the axial cross-section of the grinding wheel (or disk milling tool). With the system, the grinding wheel (or disk milling tool) axial cross-section that corresponds to the three-arc flute cross section can be conveniently simulated. Through the grinding experiment of drill flutes, the method and the CAD system are proved to be feasible and reasonable.展开更多
We present the solid model edit distance(SMED),a powerful and flexible paradigm for exploiting shape similarities amongst CAD models.It is designed to measure the magnitude of distortions between two CAD models in bou...We present the solid model edit distance(SMED),a powerful and flexible paradigm for exploiting shape similarities amongst CAD models.It is designed to measure the magnitude of distortions between two CAD models in boundary representation(B-rep).We give the formal definition by analogy with graph edit distance,one of the most popular graph matching methods.To avoid the expensive computational cost potentially caused by exact computation,an approximate procedure based on the alignment of local structure sets is provided in addition.In order to verify the flexibility,we make intensive investigations on three typical applications in manufacturing industry,and describe how our method can be adapted to meet the various requirements.Furthermore,a multilevel method is proposed to make further improvements of the presented algorithm on both effectiveness and efficiency,in which the models are hierarchically segmented into the configurations of features.Experiment results show that SMED serves as a reasonable measurement of shape similarity for CAD models,and the proposed approach provides remarkable performance on a real-world CAD model database.展开更多
Three-dimensional(3D)tracking of rigid objects plays a very important role in many areas such as augmented reality,computer vision,and robotics.Numerous works have been done to pursue more stable,faster,and more accur...Three-dimensional(3D)tracking of rigid objects plays a very important role in many areas such as augmented reality,computer vision,and robotics.Numerous works have been done to pursue more stable,faster,and more accurate 3D tracking.Among various tracking methods,edge-based 3D tracking has been widely used owing to its many advantages.Furthermore,edge-based methods can be mainly divided into two categories,methods without and those with explicit edges,depending on whether explicit edges need to be extracted.Based on this,representative methods in both categories are introduced,analyzed,and compared in this paper.Finally,some suggestions on the choice of methods in different application scenarios and research directions in the future are given.展开更多
Logic components are used to support the conceptual design Taking the stamping die structure as the research object,several logic components are defined for the conceptual die construction design A new method log...Logic components are used to support the conceptual design Taking the stamping die structure as the research object,several logic components are defined for the conceptual die construction design A new method logic assembly modeling is presented to satisfy the characteristic of the top down die design process Representing shapes and spatial relations in logic can provide a natural,intuitive method of developing complete computer systems for reasoning about die construction design at the conceptual stage This method can reflect the designer's thought clearly and provide the designer with a test bed for generating alternatives and performing reasoning work at the conceptual die design stage展开更多
Model classification is essential to the management and reuse of 3D CAD models.Manual model classification is laborious and error prone.At the same time,the automatic classification methods are scarce due to the intri...Model classification is essential to the management and reuse of 3D CAD models.Manual model classification is laborious and error prone.At the same time,the automatic classification methods are scarce due to the intrinsic complexity of 3D CAD models.In this paper,we propose an automatic 3D CAD model classification approach based on deep neural networks.According to prior knowledge of the CAD domain,features are selected and extracted from 3D CAD models first,and then preprocessed as high dimensional input vectors for category recognition.By analogy with the thinking process of engineers,a deep neural network classifier for 3D CAD models is constructed with the aid of deep learning techniques.To obtain an optimal solution,multiple strategies are appropriately chosen and applied in the training phase,which makes our classifier achieve better performance.We demonstrate the efficiency and effectiveness of our approach through experiments on 3D CAD model datasets.展开更多
The geometrical and topological information of 3D computer aided design (CAD) models should be represented as a neut- ral format file to exchange the data between different CAD systems. Exchange of 3D CAD model data...The geometrical and topological information of 3D computer aided design (CAD) models should be represented as a neut- ral format file to exchange the data between different CAD systems. Exchange of 3D CAD model data implies that the companies must exchange complete information about their products, all the way from design, manufacturing to inspection and shipping. This informa- tion should be available to each relevant partner over the entire life cycle of the product. This led to the development of an international standard organization (ISO) neutral format file named as standard for the exchange of product model data (STEP). It has been ob- served from the literature, the feature recognition systems developed were identified as planar, cylindrical, conical and to some extent spherical and toroidal surfaces. The advanced surface features such as B-spline and its subtypes are not identified. Therefore, in this work, a STEP-based feature recognition system is developed to recognize t--spline surface features and its sub-types from the 3D CAD model represented in AP203 neutral file format. The developed feature recognition system is implemented in Java programming language and the product model data represented in STEP AP203 format is interpreted through Java standard data access interface (JSDAI). The developed system could recognize B-spline surface features such as B-Spline surface with knots, quasi uniform surface, uniform surface, rational surface and Bezier surface. The application of extracted B-spline surface features information is discussed with reference to the toolpath generation for STEP-NC (STEP AP238).展开更多
文摘The current computer-aided technologies in design and product development, the evolution of CAD modeling, and a framework of multi-volume CADmodeling system for heterogeneous object design and fabrication are presented inthis paper. The multi-volume CAD modeling system is presented based on nonmanifold topological elements. Material identifications are defined as design attributes introduced along with geometric and topological information at the designstage. Extended Euler operation and reasoning Boolean operations for merging andextraction are executed according to the associated material identifications in thedeveloped multi-volume modeling system for heterogeneous object. An applicationexample and a pseudo-processing algorithm for prototyping of heterogeneous structure through solid free-form fabrication are also described.
基金supported by the National Natural Science Foundation of China(62072348)the Science and Technology Major Project of Hubei Province(Next-Generation AI Technologies,2019AEA170).
文摘Cloud manufacturing is one of the three key technologies that enable intelligent manufacturing.This paper presents a novel attribute-based encryption(ABE)approach for computer-aided design(CAD)assembly models to effectively support hierarchical access control,integrity verification,and deformation protection for co-design scenarios in cloud manufacturing.An assembly hierarchy access tree(AHAT)is designed as the hierarchical access structure.Attribute-related ciphertext elements,which are contained in an assembly ciphertext(ACT)file,are adapted for content keys decryption instead of CAD component files.We modify the original Merkle tree(MT)and reconstruct an assembly MT.The proposed ABE framework has the ability to combine the deformation protection method with a content privacy of CAD models.The proposed encryption scheme is demonstrated to be secure under the standard assumption.Experimental simulation on typical CAD assembly models demonstrates that the proposed approach is feasible in applications.
基金Supported by National Natural Science Foundation of China (Grant No.51175287)National Science and Technology Major Project of China (Grant No.2011ZX02403)
文摘CAD model retrieval based on functional semantics is more significant than content-based 3D model retrieval during the mechanical conceptual design phase. However, relevant research is still not fully discussed. Therefore, a functional semantic-based CAD model annotation and retrieval method is proposed to support mechanical conceptual design and design reuse, inspire designer creativity through existing CAD models, shorten design cycle, and reduce costs. Firstly, the CAD model functional semantic ontology is constructed to formally represent the functional semantics of CAD models and describe the mechanical conceptual design space comprehensively and consistently. Secondly, an approach to represent CAD models as attributed adjacency graphs(AAG) is proposed. In this method, the geometry and topology data are extracted from STEP models. On the basis of AAG, the functional semantics of CAD models are annotated semi-automatically by matching CAD models that contain the partial features of which functional semantics have been annotated manually, thereby constructing CAD Model Repository that supports model retrieval based on functional semantics. Thirdly, a CAD model retrieval algorithm that supports multi-function extended retrieval is proposed to explore more potential creative design knowledge in the semantic level. Finally, a prototype system, called Functional Semantic-based CAD Model Annotation and Retrieval System(FSMARS), is implemented. A case demonstrates that FSMARS can successfully botain multiple potential CAD models that conform to the desired function. The proposed research addresses actual needs and presents a new way to acquire CAD models in the mechanical conceptual design phase.
基金Supported by College Science Foundation of Jiangsu(07KJB460113)
文摘An algorithm for compensating the varying section contour within the extent of each layer thickness is proposed to improve the rapid prototyping part’s shape and size precision.
基金This project is supported by National Natural Science Foundation of China (No.50675065).
文摘Based on the principles of differential geometry and kinematics, a mathematical model is developed to describe the grinding wheel axial cross-section with the radial cross-section of the flute in a given drill under the basic engagement condition between the generating flute and the generated grinding wheel (or disk milling tool). The mathematical model is good for the flute in the radial cross-section consisting of three arcs. Furthermore, a CAD system is also developed to represent the axial cross-section of the grinding wheel (or disk milling tool). With the system, the grinding wheel (or disk milling tool) axial cross-section that corresponds to the three-arc flute cross section can be conveniently simulated. Through the grinding experiment of drill flutes, the method and the CAD system are proved to be feasible and reasonable.
基金Supported by National Science Foundation of China(61373071)
文摘We present the solid model edit distance(SMED),a powerful and flexible paradigm for exploiting shape similarities amongst CAD models.It is designed to measure the magnitude of distortions between two CAD models in boundary representation(B-rep).We give the formal definition by analogy with graph edit distance,one of the most popular graph matching methods.To avoid the expensive computational cost potentially caused by exact computation,an approximate procedure based on the alignment of local structure sets is provided in addition.In order to verify the flexibility,we make intensive investigations on three typical applications in manufacturing industry,and describe how our method can be adapted to meet the various requirements.Furthermore,a multilevel method is proposed to make further improvements of the presented algorithm on both effectiveness and efficiency,in which the models are hierarchically segmented into the configurations of features.Experiment results show that SMED serves as a reasonable measurement of shape similarity for CAD models,and the proposed approach provides remarkable performance on a real-world CAD model database.
基金Special Program of the Ministry of Industry and Information Technology of China.
文摘Three-dimensional(3D)tracking of rigid objects plays a very important role in many areas such as augmented reality,computer vision,and robotics.Numerous works have been done to pursue more stable,faster,and more accurate 3D tracking.Among various tracking methods,edge-based 3D tracking has been widely used owing to its many advantages.Furthermore,edge-based methods can be mainly divided into two categories,methods without and those with explicit edges,depending on whether explicit edges need to be extracted.Based on this,representative methods in both categories are introduced,analyzed,and compared in this paper.Finally,some suggestions on the choice of methods in different application scenarios and research directions in the future are given.
文摘Logic components are used to support the conceptual design Taking the stamping die structure as the research object,several logic components are defined for the conceptual die construction design A new method logic assembly modeling is presented to satisfy the characteristic of the top down die design process Representing shapes and spatial relations in logic can provide a natural,intuitive method of developing complete computer systems for reasoning about die construction design at the conceptual stage This method can reflect the designer's thought clearly and provide the designer with a test bed for generating alternatives and performing reasoning work at the conceptual die design stage
基金Project supported by the National Natural Science Foundation of China(Nos.61163016 and 61173125)
文摘Model classification is essential to the management and reuse of 3D CAD models.Manual model classification is laborious and error prone.At the same time,the automatic classification methods are scarce due to the intrinsic complexity of 3D CAD models.In this paper,we propose an automatic 3D CAD model classification approach based on deep neural networks.According to prior knowledge of the CAD domain,features are selected and extracted from 3D CAD models first,and then preprocessed as high dimensional input vectors for category recognition.By analogy with the thinking process of engineers,a deep neural network classifier for 3D CAD models is constructed with the aid of deep learning techniques.To obtain an optimal solution,multiple strategies are appropriately chosen and applied in the training phase,which makes our classifier achieve better performance.We demonstrate the efficiency and effectiveness of our approach through experiments on 3D CAD model datasets.
文摘The geometrical and topological information of 3D computer aided design (CAD) models should be represented as a neut- ral format file to exchange the data between different CAD systems. Exchange of 3D CAD model data implies that the companies must exchange complete information about their products, all the way from design, manufacturing to inspection and shipping. This informa- tion should be available to each relevant partner over the entire life cycle of the product. This led to the development of an international standard organization (ISO) neutral format file named as standard for the exchange of product model data (STEP). It has been ob- served from the literature, the feature recognition systems developed were identified as planar, cylindrical, conical and to some extent spherical and toroidal surfaces. The advanced surface features such as B-spline and its subtypes are not identified. Therefore, in this work, a STEP-based feature recognition system is developed to recognize t--spline surface features and its sub-types from the 3D CAD model represented in AP203 neutral file format. The developed feature recognition system is implemented in Java programming language and the product model data represented in STEP AP203 format is interpreted through Java standard data access interface (JSDAI). The developed system could recognize B-spline surface features such as B-Spline surface with knots, quasi uniform surface, uniform surface, rational surface and Bezier surface. The application of extracted B-spline surface features information is discussed with reference to the toolpath generation for STEP-NC (STEP AP238).