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CONTENTS
Volume 1, Number 1, January 2014
 

Abstract
In this paper, we propose a new method of reconstructing the hand models for individuals, which include the link structure models, the homologous skin surface models and the homologous tetrahedral mesh models in a reference posture. As for the link structure model, the local coordinate system related to each link consists of the joint rotation center and the axes of joint rotation, which can be estimated based on the trajectories of optimal markers on the relative skin surface region of the subject obtained from the motion capture system. The skin surface model is defined as a three-dimensional triangular mesh, obtained by deforming a template mesh so as to fit the land- mark vertices to the relative marker positions obtained motion capture system. In this process, anatomical dimensions for the subject, manually measured by a caliper, are also used as the deformation constraints.

Key Words
Digital human modeling; Digital hand; Motion capture; Joint center estimation

Address
Digital Human Research Center, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan

Abstract
Recently, renovations of plant equipment have been more frequent because of the shortened lifespans of the products, and as-built models from large-scale laser-scanned data is expected to streamline rebuilding processes. However, the laser-scanned data of an existing plant has an enormous amount of points, captures intricate objects, and includes a high noise level, so the manual reconstruction of a 3D model is very time-consuming and costly. Among plant equipment, piping systems account for the greatest proportion. Therefore, the purpose of this research was to propose an algorithm which could automatically recognize a piping system from the terrestrial laser- scanned data of plant equipment. The straight portion of pipes, connecting parts, and connection relationship of the piping system can be recognized in this algorithm. Normal-based region growing and cylinder surface fitting can extract all possible locations of pipes, includ- ing straight pipes, elbows, and junctions. Tracing the axes of a piping system enables the recognition of the positions of these elements and their connection relationship. Using only point clouds, the recognition algorithm can be performed in a fully automatic way. The algorithm was applied to large-scale scanned data of an oil rig and a chemical plant. Recognition rates of about 86%, 88%, and 71% were achieved straight pipes, elbows, and junctions, respectively.

Key Words
Laser scanning; Object recognition; As-built model; Piping system; Point clouds

Address
Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan

Abstract
Similar to the essential components of many mechanical systems, the geometrical properties of the teeth of spiral bevel gears greatly influence the kinematic and dynamic behaviors of mechanical systems. Logarithmic spiral bevel gears show a unique advantage in transmission due to their constant spiral angle property. However, a mathematical model suitable for accurate digital modeling, differen- tial geometrical characteristics, and related contact analysis methods for tooth surfaces have not been deeply investigated, since such gears are not convenient in traditional cutting manufacturing in the gear industry. Accurate mathematical modeling of the tooth surface geometry for logarithmic spiral bevel gears is developed in this study, based on the basic gearing kinematics and spherical involute ge- ometry along with the tangent planes geometry; actually, the tooth surface is a parametric surface defined on a parallelogrammic domain. Equivalence proof of the tooth surface geometry is then given in order to greatly simplify the mathematical model. As major factors af- fecting the lubrication, surface fatigue, contact stress, wear, and manufacturability of gear teeth, the differential geometrical characteris- tics of the tooth surface are summarized using classical fundamental forms. By using the geometrical properties mentioned, manufactura- bility (and its limitation in logarithmic spiral bevel gears) is analyzed using precision forging and multi-axis freeform milling, rather than classical cradle-type machine tool based milling or hobbing. Geometry and manufacturability analysis results show that logarithmic spiral gears have many application advantages, but many urgent issues such as contact tooth analysis for precision plastic forming and multi- axis freeform milling also need to be solved in a further study.

Key Words
Spiral bevel gear; Mathematical modeling; Parametric surface; Geometrical characteristics; Manufacturability

Address
Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, China

Abstract
We propose a new generic design methodology for different types of PSS. Product – Service System (PSS) has received much atten- tion recently from academia and industry because of its benefits. PSS can provide customers values and functionalities, as well as physi- cal products, to fulfill economic, social and environmental goals.Many methodologies have been proposed for designing PSSs. Most of the existing methodologies are domain specific and were proposed to solve specific problems in certain projects. Some methodologies are generic but they provide neither guideline to practitioners and designers nor reflect the differences in various PSS types. As a generic approach to guide practitioners and designers in designing PSS effectively, the proposed methodology also takes into account user in- volvement, business model and organizational structure. The proposed methodology is demonstrated through design examples of differ- ent types of PSSs.

Key Words
PSS; Product service system; Design methodology; Product service integration; Integrated design methodology

Address
Digital Product Lab, Department of Industrial and Systems Engineering, Dongguk University, Pil dong, Jung gu, Seoul, KOREA

Abstract
In this paper, the authors propose a system for assisting mold designers of plastic parts. With a CAD model of a part, the system auto- matically determines the optimal ejecting direction of the part with minimum undercuts. Since plastic parts are generally very thin, many rib features are placed on the inner side of the part to give sufficient structural strength. Our system extracts the rib features from the CAD model of the part, and determines the possible ejecting directions based on the geometric properties of the features. The system then selects the optimal direction with minimum undercuts. Possible ejecting directions are represented as discrete points on a Gauss map. Our new point distribution method for the Gauss map is based on the concept of the architectural geodesic dome. A hierarchical structure is also introduced in the point distribution, with a higher level

Key Words
Ejecting direction; Undercut detection; Injection molding; Feature recognition; Concurrent engineering; CAD

Address
Department of Intelligent Systems Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki, Japan

Abstract
A knee joint´s longevity depends on the proper integration of structural components in an axial alignment. If just one of the compo- nents is abnormally off-axis, the biomechanical system fails, resulting in arthritis. The complexity of various failures in the knee joint has led orthopedic surgeons to select total knee replacement as a primary treatment. In many cases, this means sacrificing much of an other- wise normal joint. Here, we review novel computational approaches to describe knee physiotherapy by introducing a new dimension of foot loading to the knee axis alignment producing an improved functional status of the patient. New physiotherapeutic applications are then possible by aligning foot loading with the functional axis of the knee joint during the treatment of patients with osteoarthritis.

Key Words
Instantaneous axes of the knee (IAK); Cylindroidal coordinates; Perception-action coupling manifold; Gibson

Address
Wangdo Kim, António P. Veloso and Duarte Araújo : Univ Lisboa, Fac Motricidade Humana, CIPER, LBMF, SPERTLAB, Estrada da Costa, P-1499-002, Lisbon, Portugal
Sean S. Kohles: Division of Biomaterials & Biomechanics, Department of Restorative Dentistry, Oregon Health & Science University, Portland, Oregon, USA

Abstract
Most engineering software tools use typical menu-based user interfaces, and they may not be suitable for learning tools because the so- lution processes are hidden and students can only see the results. An educational tool for simple beam analyses is developed using a pen- based user interface with a computer so students can write and sketch by hand. The geometry of beam sections is sketched, and a shape matching technique is used to recognize the sketch. Various beam loads are added by sketching gestures or writing singularity functions. Students sketch the distributions of the loadings by sketching the graphs, and they are automatically checked and the system provides aids in grading the graphs. Students receive interactive graphical feedback for better learning experiences while they are working on solv- ing the problems.

Key Words
Beam loading analysis; Pen-based interface; Education software; Shape matching

Address
Department of Mechanical Engineering, California State University, Sacramento, 6000 J Street, Sacramento, CA, U.S.A.


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