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Research Papers

J. Comput. Inf. Sci. Eng. 2017;17(3):031001-031001-9. doi:10.1115/1.4034737.

In the geometric simulation of multi-axis milling, a dexel representation solid model is frequently used. In this modeling method, the object shape is defined as a collection of vertical segments (dexels) based on a two-dimensional regular square grid in the XY plane. In this paper, the authors propose the quad pillars algorithm and its enhanced version named the delta pillars algorithm for converting a dexel model to an equivalent polyhedral stereolithography (STL) model. These algorithms define a series of vertical pillar shapes for each square cell of the grid to represent the object shape as a bundle of pillars. The final polyhedral model is obtained by performing a simplified Boolean union operation of the pillar shapes. Unlike prior methods, the proposed algorithms are simple and fast and are guaranteed to generate a watertight polyhedral model without holes, gaps, or T-junctions. An experimental system is implemented and conversion tests are performed. The system converted a dexel model based on a high-resolution grid to a polyhedral model in a practical amount of time.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031002-031002-16. doi:10.1115/1.4035673.

New business models and more integrated product development processes require designers to make use of knowledge more efficiently. Capture and reuse are means of coping, but support, techniques, and mechanisms have yet to be sufficiently addressed. This paper consequently explores how computer-aided technologies (CAx) and a computer-aided design (CAD) model-oriented approach can be used to improve the efficiency of design module capture and representation for product family reuse. The first contribution of this paper is the investigation performed at a Swedish manufacturing company and a set of identified challenges related to design capture and representation for reuse in product family development. The second contribution is a demonstrated and evaluated set of systems and tools, which exemplifies how these challenges can be approached. Efficient design capture is achieved by a combination of automated and simplified design capture, derived from the design implementation (CAD model definition) to the extent possible. Different design representations can then be accessed by the designer using the CAD-internal tool interface. A web application is an example of more general-purpose representation to tailor design content, all of which is managed by a product lifecycle management (PLM) system. Design capture is based on a modular view block definition, stored in formal information models, management by a PLM system, for consistent and reliable design content. It was, however, introduced to support the rich and expressive forms of capture and representation required to facilitate understanding, use, and reuse of varied and increasingly complex designs. A key element in being able to describe a complex design and its implementation has been capture and representation of a set of design states. The solution has been demonstrated to effectively be able to capture and represent significant portions of a step-by-step design training material and the implementation of complex design module through a set of design decisions taken. The validity and relevance of the proposed solution is strengthened by the level of acceptance and perceived value from experienced users, together with the fact that the company is implementing parts of it today.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031003-031003-10. doi:10.1115/1.4035674.

A competition for teams of three students using a prototype multi-user computer-aided design (MUCAD) tool was held to investigate various hypotheses regarding the performance of teams in such a setting. By comparing models from the competition to the same model in a single-user CAD environment, it is seen that use of a MUCAD system can significantly increase the value-added per unit of calendar time for a modeling effort. An investigation was also made into the causes of the performance differences among the various MUCAD teams which participated in the competition. Analysis of the results shows that teams that encouraged effective forms of communication and teams whose members scored similarly on the Purdue Spatial Visualization Test: Visualization of Rotations (PSVT:R) performed better than other teams. Areas of future research in analyzing teams in MUCAD environments are suggested.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031004-031004-6. doi:10.1115/1.4034740.

This paper presents the design process of a novel general-purpose electric vehicle chassis as agriculture payload carrier platform to perform agricultural tasks: detection, guidance, mapping, and action. This design applied a human-centered design frameworks and processes: Kumar's seven modes of the design innovation process, and the three lenses of human-centered design by IDEO. After approach from three design-project perspectives mapping, a universal electric-powered multiwheel independent drive and independent steering robotic vehicle platform is designed for agricultural application. A real size prototype has been built to prove the design.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031005-031005-4. doi:10.1115/1.4034742.

This paper presents a design process of a novel electric wheelchair controller to enable a dual control access for both the users in the wheelchair and their caregivers. This design applied human-centered design frameworks, processes, and tools: Kumar's seven modes of the design innovation process and IDEO, Palo Alto, CA, design method cards. After such design process, a design of dual control access controller of an electric wheelchair is established. A real-size prototype has been built to prove the design concept; and further, the method of control switching between people in and behind the wheelchair has been optimized with the established prototype.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031006-031006-9. doi:10.1115/1.4033994.

The improvement and the massive diffusion of additive manufacturing (AM) techniques have fostered the research of design methods to exploit at best the feature introduced by these solutions. The whole design paradigm needs to be changed taking into account new manufacturing capabilities. AM is not only an innovative method of fabrication, but it requires a new way to design products. Traditional practices of mechanical design are changing to exploit all potential of AM, new parameters and geometries could be realized avoiding technologies constrains of molding or machine tooling. The concept of “manufacturing for design” increasingly acquires greater importance and this means we have the chance to focus almost entirely on product functionality. The possibility to confer inhomogeneous properties to objects provides an important design key. We will study behavior and structure according to desired functions for each object identifying three main aspects to vary: infill type, external topology and shape, and material composition. In this research work, we focus on fused deposition modeling (FDM) technology of three dimensional (3D) printing that easily allows to explore all previous conditions. We present a new way to conceive design process in order to confer variable properties to AM objects and some guidelines to control properties of deformation and elasticity using classic infills. The ultimate aim is to apply new design rules provided by AM in the prosthetic field of lower limb amputees. The socket of the prosthesis represents a deformable interface between the residual limb and the artificial leg that must be optimized according to geometry and loads distribution of patient. An application for a transfemoral patient will be discussed.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031007-031007-14. doi:10.1115/1.4035675.

Energy consumption in manufacturing has risen to be a global concern. Material selection in the product design phase is of great significance to energy conservation and emission reduction. However, because of the limitation of the current life-cycle energy analysis and optimization method, such concerns have not been adequately addressed in material selection. To fill in this gap, a process to build a comprehensive multi-objective optimization model for automated multimaterial selection (MOO–MSS) on the basis of cloud manufacturing is developed in this paper. The optimizing method, named local search-differential group leader algorithm (LS-DGLA), is a hybrid of differential evolution and local search with the group leader algorithm (GLA), constructed for better flexibility to handle different needs for various product designs. Compared with a number of evolutionary algorithms and nonevolutionary algorithms, it is observed that LS-DGLA performs better in terms of speed, stability, and searching capability.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031008-031008-13. doi:10.1115/1.4034436.

Engineering design is increasingly recognized as a decision making process. Providing decision support is crucial to augment designers' decision-making capability in this process. In this paper, we present a template-based ontological method that integrates the decision-making mechanism with problem-specific information; thus, it can provide design decision support from both the “construct” and the “information” perspectives. The “construct,” namely, decision-making mechanism, is the utility-based Decision Support Problem (u-sDSP), which is a rigorous mathematical model that facilitates designers making multi-attribute selection decisions under uncertainty, while the information for decision making is archived as u-sDSP templates and represented using frame-based ontology to facilitate reuse, execution, and consistency-maintaining. This paper is an extension of our earlier work on the ontological modeling of the compromise decisions. The unique advantage of this ontology is that it captures both the declarative and procedural knowledge of selection decisions and represents them separately, thus facilitating designers reusing, executing previous documented decision knowledge to effect new decisions. The efficacy of ontology is demonstrated using a rapid prototyping (RP) resource selection example.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031009-031009-11. doi:10.1115/1.4034387.

Freehand sketching is an integral part of early design process. Recent years have seen an increased interest in supporting sketching in computer-based design systems. In this paper, we present finite element analysis made easy (FEAsy), a naturalistic environment for static finite element analysis. This tool allows users to transform, simulate, and analyze their finite element models quickly and easily through freehand sketching. A major challenge here is to beautify freehand sketches, and to this extent, we present a domain-independent, multistroke, multiprimitive method which automatically detects and uses the spatial relationships implied in the sketches for beautification. Further, we have also developed a domain-specific rules-based algorithm for recognizing commonly used symbols in finite element analysis (FEA) and a method for identifying different contexts in finite element modeling through combined interpretation of text and geometry. The results of the user study suggest that our proposed algorithms are efficient and robust. Pilot users found the interface to be effective and easy to use.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031010-031010-9. doi:10.1115/1.4035001.

With design teams becoming more distributed, the sharing and interpreting of complex data about design concepts/prototypes and environments have become increasingly challenging. The size and quality of data that can be captured and shared directly affects the ability of receivers of that data to collaborate and provide meaningful feedback. To mitigate these challenges, the authors of this work propose the real-time translation of physical objects into an immersive virtual reality environment using readily available red, green, blue, and depth (RGB-D) sensing systems and standard networking connections. The emergence of commercial, off-the-shelf RGB-D sensing systems, such as the Microsoft Kinect, has enabled the rapid three-dimensional (3D) reconstruction of physical environments. The authors present a method that employs 3D mesh reconstruction algorithms and real-time rendering techniques to capture physical objects in the real world and represent their 3D reconstruction in an immersive virtual reality environment with which the user can then interact. Providing these features allows distributed design teams to share and interpret complex 3D data in a natural manner. The method reduces the processing requirements of the data capture system while enabling it to be portable. The method also provides an immersive environment in which designers can view and interpret the data remotely. A case study involving a commodity RGB-D sensor and multiple computers connected through standard TCP internet connections is presented to demonstrate the viability of the proposed method.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031011-031011-11. doi:10.1115/1.4035528.

This paper studies the problem of planar four-bar motion generation from the viewpoint of extraction of geometric constraints from a given set of planar displacements. Using the image space of planar displacements, we obtain a class of quadrics, called generalized- or G-manifolds, with eight linear and homogeneous coefficients as a unified representation for constraint manifolds of all four types of planar dyads, RR, PR, and PR, and PP. Given a set of image points that represent planar displacements, the problem of synthesizing a planar four-bar linkage is reduced to finding a pencil of G-manifolds that best fit the image points in the least squares sense. This least squares problem is solved using singular value decomposition (SVD). The linear coefficients associated with the smallest singular values are used to define a pencil of quadrics. Additional constraints on the linear coefficients are then imposed to obtain a planar four-bar linkage that best guides the coupler through the given displacements. The result is an efficient and linear algorithm that naturally extracts the geometric constraints of a motion and leads directly to the type and dimensions of a mechanism for motion generation.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031012-031012-10. doi:10.1115/1.4036552.

Spatial variation of material structures is a principal mechanism for creating and controlling spatially varying material properties in nature and engineering. While the spatially varying homogenized properties can be represented by scalar and vector fields on the macroscopic scale, explicit microscopic structures of constituent phases are required to facilitate the visualization, analysis, and manufacturing of functionally graded material (FGM). The challenge of FGM structure modeling lies in the integration of these two scales. We propose to represent and control material properties of FGM at macroscale using the notion of material descriptors, which include common geometric, statistical, and topological measures, such as volume fraction, correlation functions, and Minkowski functionals. At microscale, the material structures are modeled as Markov random fields (MRFs): we formulate the problem of design and (re)construction of FGM structure as a process of selecting neighborhoods from a reference FGM, based on target material descriptors fields. The effectiveness of the proposed method in generating a spatially varying structure of FGM with target properties is demonstrated by two examples: design of a graded bone structure and generating functionally graded lattice structures with target volume fraction fields.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031013-031013-15. doi:10.1115/1.4036921.

In the past few years, there have been some significant advances in consumer virtual reality (VR) devices. Devices such as the Oculus Rift, HTC Vive, Leap Motion™ Controller, and Microsoft Kinect® are bringing immersive VR experiences into the homes of consumers with much lower cost and space requirements than previous generations of VR hardware. These new devices are also lowering the barrier to entry for VR engineering applications. Past research has suggested that there are significant opportunities for using VR during design tasks to improve results and reduce development time. This work reviews the latest generation of VR hardware and reviews research studying VR in the design process. Additionally, this work extracts the major themes from the reviews and discusses how the latest technology and research may affect the engineering design process. We conclude that these new devices have the potential to significantly improve portions of the design process.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031014-031014-16. doi:10.1115/1.4036991.
FREE TO VIEW

The importance of physiotherapy is becoming more significant with the increasing number of countries with aging populations. Thus, the education of physiotherapists is a crucial concern in many countries. Information and communications technologies, such as motion capture systems, have been introduced to sophisticate the training methods used in physiotherapy. However, the methods employed in most training schools for physiotherapists and occupational therapists remain dependent on more conventional materials. These materials include conventional textbooks with samples of traditional gait motion photographs and video archives of patients' walking motion. Actual on-site clinical training is also utilized in current physiotherapy education programs. The present paper addresses an application of a previously developed digital human model called the kinematic digital human (KDH) to physiotherapy education with a focus on improving students' understanding of the gait motion of disabled patients. KDH models for use in physiotherapy were constructed based on Rancho Los Amigos National Rehabilitation Center (RLANRC) terminology, which is considered the preferred standard among clinicians. The developed KDH models were employed to allow the three-dimensional visualization of the gait motion of a hemiplegic patient.

Topics: Kinematics
Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031015-031015-8. doi:10.1115/1.4037229.

This paper presents a design methodology for a system of linkages that can trace planar Bezier curves that represent cursive handwriting of the alphabet and Chinese characters. This paper shows that the standard degree n Bezier curve can be reparameterized so that it takes the form of a trigonometric curve that can be drawn by a one degree-of-freedom coupled serial chain consisting of 2n links. A series of cubic Bezier curves that define a handwritten name yields a series of six-link coupled serial chains that trace these curves. We then show how to simplify this system using cubic trigonometric Bezier curves to obtain a series of four-link serial chains that approximate the system of Bezier curves. The result is a methodology for the design of a mechanical system that draws complex plane curves such as the cursive alphabet and Chinese characters.

Topics: Linkages , Chain , Design
Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031016-031016-9. doi:10.1115/1.4037178.
FREE TO VIEW

The need for capturing knowledge in the digital form in design, process planning, production, and inspection has increasingly become an issue in manufacturing industries as the variety and complexity of product lifecycle applications increase. Both knowledge and data need to be well managed for quality assurance, lifecycle impact assessment, and design improvement. Some technical barriers exist today that inhibit industry from fully utilizing design, planning, processing, and inspection knowledge. The primary barrier is a lack of a well-accepted mechanism that enables users to integrate data and knowledge. This paper prescribes knowledge management to address a lack of mechanisms for integrating, sharing, and updating domain-specific knowledge in smart manufacturing (SM). Aspects of the knowledge constructs include conceptual design, detailed design, process planning, material property, production, and inspection. The main contribution of this paper is to provide a methodology on what knowledge manufacturing organizations access, update, and archive in the context of SM. The case study in this paper provides some example knowledge objects to enable SM.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031017-031017-10. doi:10.1115/1.4037179.

This paper presents the use of subassembly models instead of the entire assembly model to predict assembly quality defects at an automotive original equipment manufacturer (OEM). Specifically, artificial neural networks (ANNs) were used to predict assembly time and market value from assembly models. These models were converted into bipartite graphs from which 29 graph complexity metrics were extracted to train 18,900 ANN prediction models. The size of the training set, order of the bipartite graph, selection of training set, and defect type were experimentally studied. With a training size of 28 parts, an interpolation focused training set selection with a second-order graph seeding ensured that 70% of all predictions were within 100% of the target value. The study shows that with an increase in training size and careful selection of training sets, assembly defects can be predicted reliably from subassemblies' complexity data.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2017;17(3):031018-031018-11. doi:10.1115/1.4037228.

The software is often responsible for controlling the behavior of mechanical and electrical components, as well as interactions among these components in cyber-physical systems (CPS). The risks in CPS systems could result in losing tools, features, performance and even life. Therefore, safety analysis for software in these systems is a highly critical and serious issue. In general, safety and reliability approaches play a major role in a risk management process in CPS. In this paper, after reviewing the major techniques of software reliability and safety in CPS, an software fault tree analysis (SFTA)-based approach is presented for analysis of operational use-cases (UC) in a CPS system. In our approach, the events related to use-cases are extracted, and the related SFTA is then obtained using the proposed algorithm. Moreover, a semi-automatic method is presented in this paper to produce software failure mode and effects analysis (SFMEA) from SFTA. The results of our approach are applicable for software safety analysis in a real CPS system, including the control system of Iranian National Observatory telescope. Assessment of the suggested method is performed through numerous safety/reliability criteria and the qualitative/quantitative analysis based on these criteria.

Commentary by Dr. Valentin Fuster

Technical Brief

J. Comput. Inf. Sci. Eng. 2017;17(3):034501-034501-6. doi:10.1115/1.4037180.

The saxophone mouthpiece is an important, sound generating component of this instrument. The structure of mouthpiece has undergone several design changes since its invention by Adolphe Sax in the mid-18th century. Very few antique mouthpieces survived through the years, and unfortunately, those available are not playable on modern saxophones due to geometric discrepancies. This paper investigates the possibility of using three-dimensional (3D) X-ray tomography and 3D printing combined with solid modeling and reverse engineering concepts to bring back the sound of saxophones as intended by its inventor. We have imaged the interior and exterior of an extant mouthpiece nondestructively using 3D X-ray tomography, and used solid modeling and reverse engineering along with sound testing, to optimize the geometry of a mouthpiece that is faithful to its original design and yet playable on a modern saxophone. To perform sound testing of our design iterations, 3D printed prototypes have been used and proven to generate sufficient sound quality for testing. We have successfully obtained the optimized geometry after a series of iterations that taught us valuable lessons about modeling for 3D printing and correlating geometric features of a mouthpiece to its sound quality. Though the developed principles are applied to saxophone mouthpieces, the present work can be readily extended to various musical instruments that have evolved through time, particularly woodwind instruments and instruments with mouthpieces.

Commentary by Dr. Valentin Fuster

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