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Ikuru OTOMO,Masahiko ONOSATO,Fumiki TANAKA (사)한국CDE학회 2013 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8
In the field of design and manufacturing, there are many problems on managing dynamic states of three-dimensional (3D) objects. In order to solve these problems, the four-dimensional (4D) mesh model and its modeling system have been proposed. The 4D mesh model is defined as a 4D object model that is bounded by tetrahedral cells, and it can represent spatio-temporal changes of a 3D object continuously. By using the 4D mesh model, it helps to solve dynamic problems of 3D models as geometric problems. However, the construction of the 4D mesh model is limited on timeseries 3D voxel data based method. This method is memory-hogging and requires much computing time. In this research, we propose a new method of constructing the 4D mesh model that is from 3D mesh model with continuous rigid body movement. This method is realized by making a swept shape of a 3D mesh model in the fourth dimension and its tetrahedralization. Here, the rigid body movement is screwed movement, which is a combination of translational and rotational movement. At first, this report introduces the summary of a 4D mesh model and its modeling system. Then, the proposed method of constructing the 4D mesh model is explained in detail.
Takahashi, Keita,Onosato, Masahiko,Tanaka, Fumiki Society for Computational Design and Engineering 2015 Journal of computational design and engineering Vol.2 No.2
Product Lifecycle Management (PLM) ranges from design concepts of products to disposal. In this paper, we focus on the production planning phase in PLM, which is related to process planning and production scheduling and so on. In this study, key decisions for the creation of production plans are defined as production-planning attributes. Production-planning attributes correlate complexly in production-planning problems. Traditionally, the production-planning problem splits sub-problems based on experiences, because of the complexity. In addition, the orders in which to solve each sub-problem are determined by priorities between sub-problems. However, such approaches make solution space over-restricted and make it difficult to find a better solution. We have proposed a representation of combinations of alternatives in production-planning attributes by using Zero-Suppressed Binary Decision Diagrams. The ZDD represents only feasible combinations of alternatives that satisfy constraints in the production planning. Moreover, we have developed a solution search method that solves production-planning problems with ZDDs. In this paper, we propose an approach for managing solution candidates by ZDDs' network for addressing larger production-planning problems. The network can be created by linkages of ZDDs that express constraints in individual sub-problems and between sub-problems. The benefit of this approach is that it represents solution space, satisfying whole constraints in the production planning. This case study shows that the validity of the proposed approach.
Otomo, Ikuru,Onosato, Masahiko,Tanaka, Fumiki Society for Computational Design and Engineering 2014 Journal of computational design and engineering Vol.1 No.2
In the field of design and manufacturing, there are many problems with managing dynamic states of three-dimensional (3D) objects. In order to solve these problems, the four-dimensional (4D) mesh model and its modeling system have been proposed. The 4D mesh model is defined as a 4D object model that is bounded by tetrahedral cells, and can represent spatio-temporal changes of a 3D object continuously. The 4D mesh model helps to solve dynamic problems of 3D models as geometric problems. However, the construction of the 4D mesh model is limited on the time-series 3D voxel data based method. This method is memory-hogging and requires much computing time. In this research, we propose a new method of constructing the 4D mesh model that derives from the 3D mesh model with continuous rigid body movement. This method is realized by making a swept shape of a 3D mesh model in the fourth dimension and its tetrahedralization. Here, the rigid body movement is a screwed movement, which is a combination of translational and rotational movement.
Dimension-driven deformation and untangling of tetrahedral meshes
Yuki Takano,Hiroaki Date,Masahiko Onosato (사)한국CDE학회 2010 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8
In this paper, we propose a dimension-driven deformation method of tetrahedral meshes using space-embedding. The vertices of the mesh are classified into surface vertices and interior vertices and each type of vertex is repositioned separately. Surface vertices are moved so as to satisfy the target dimensions using barycentric coordinates. Interior vertices are repositioned so that it follows the deformation of the surface mesh by using mean value coordinates. As a result of the tetrahedral mesh deformation, tangled tetrahedra often occur. The tangled tetrahedra affect the accuracy of the finite element analysis. Therefore, we propose a method for modifying the tangled tetrahedra. In this method, by solving the constrained nonlinear optimization problem, the vertices of the tangled tetrahedra are moved to the positions where the tangled tetrahedra do not occur and the mesh quality improves.