scholarly journals Computer-aided-design-model-assisted absolute three-dimensional shape measurement

2017 ◽  
Vol 56 (24) ◽  
pp. 6770 ◽  
Author(s):  
Beiwen Li ◽  
Tyler Bell ◽  
Song Zhang
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Design Model ◽  
Shape Measurement ◽  
Computer Aided ◽  
Dimensional Shape ◽  
Aided Design ◽  
Three Dimensional Shape

scholarly journals Rail wear inspection based on computer-aided design model and point cloud data

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881678 ◽  
Author(s):  
Peng Chen ◽  
Yong Hu ◽  
Wen-Tao Li ◽  
Pei-Jun Wang
Keyword(s):  
Computer Aided Design ◽  
Point Cloud ◽  
Structured Light ◽  
Three Dimensional ◽  
Point Clouds ◽  
Design Model ◽  
Inspection System ◽  
Rail Wear ◽  
Computer Aided ◽  
Aided Design

Railway transportation demands more efficient and accurate rail wear inspection systems to ensure the train operation safety. To obtain continuous three-dimensional data, a structured light rail wear inspection system is developed in this article, and the data processing method for aligning the point cloud from structured light scanning to the nominal computer-aided design model of the rail is investigated. For further data registration, the point cloud of the computer-aided design model is generated and the normal vectors of these points are calculated. In the coarse registration, conformal geometric algebra is applied to align the segmented point clouds by intuitive geometric calculations to those from the computer-aided design model. In the fine registration, the accurate alignment of the point clouds is implemented by the iterative closest point algorithm. The vertical and lateral wear amounts are obtained on the cross section by slicing the aligned three-dimensional point clouds data. Finally, the proposed system and method are validated by comparing the vertical wear amounts with the two-dimensional laser scanning and contact measurement results.

scholarly journals Determination of appropriate level of detail of a three-dimensional computer-aided design model from a permissible dissimilarity for fully automated simplification

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401770712 ◽  
Author(s):  
Soonjo Kwon ◽  
Hyungki Kim ◽  
Duhwan Mun ◽  
Soonhung Han
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Level Of Detail ◽  
Design Model ◽  
Prototype System ◽  
Design Models ◽  
Automated Method ◽  
Level Of Details ◽  
Computer Aided ◽  
Aided Design

The level of detail required for a three-dimensional computer-aided design model varies according to its purpose. Thus, it is necessary to develop an automated method for controlling the level of detail of three-dimensional computer-aided design models to facilitate the use of three-dimensional computer-aided design models in different application areas. When multiple three-dimensional computer-aided design models need to be simplified in a batch mode without user intervention, it would be advantageous if the appropriate level of details for the models were automatically determined. This study proposes a new and automated method to determine the appropriate level of detail of each three-dimensional computer-aided design model during the simplification phase. To achieve this goal, the concept of an “appropriate level of detail for simplification” was defined from the viewpoint of shape dissimilarity. After that, an algorithm was developed to determine the appropriate level of detail of a model by adopting the feature-based simplification method and the shape distribution–based comparison method. Finally, a prototype system was invented to verify the proposed method through experiments, in which the appropriate level of details for test cases were determined by the system.

scholarly journals Automatized Evaluation of Students’ CAD Models

2021 ◽  
Vol 11 (4) ◽  
pp. 145
Author(s):  
Nenad Bojcetic ◽  
Filip Valjak ◽  
Dragan Zezelj ◽  
Tomislav Martinec
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Computer Application ◽  
Test Cases ◽  
Cad Model ◽  
Computer Solution ◽  
3D Cad ◽  
Computer Aided ◽  
Cad Models ◽  
Aided Design

The article describes an attempt to address the automatized evaluation of student three-dimensional (3D) computer-aided design (CAD) models. The driving idea was conceptualized under the restraints of the COVID pandemic, driven by the problem of evaluating a large number of student 3D CAD models. The described computer solution can be implemented using any CAD computer application that supports customization. Test cases showed that the proposed solution was valid and could be used to evaluate many students’ 3D CAD models. The computer solution can also be used to help students to better understand how to create a 3D CAD model, thereby complying with the requirements of particular teachers.

Determination of the Workspace of a Three-Degrees-of-Freedom Parallel Manipulator Using a Three-Dimensional Computer-Aided-Design Software Package and the Concept of Virtual Chains1

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Andrew Johnson ◽  
Xianwen Kong ◽  
James Ritchie
Keyword(s):  
Computer Aided Design ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Workspace Analysis ◽  
Computer Aided ◽  
Aided Design

The determination of workspace is an essential step in the development of parallel manipulators. By extending the virtual-chain (VC) approach to the type synthesis of parallel manipulators, this technical brief proposes a VC approach to the workspace analysis of parallel manipulators. This method is first outlined before being illustrated by the production of a three-dimensional (3D) computer-aided-design (CAD) model of a 3-RPS parallel manipulator and evaluating it for the workspace of the manipulator. Here, R, P and S denote revolute, prismatic and spherical joints respectively. The VC represents the motion capability of moving platform of a manipulator and is shown to be very useful in the production of a graphical representation of the workspace. Using this approach, the link interferences and certain transmission indices can be easily taken into consideration in determining the workspace of a parallel manipulator.

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