Research Papers

J. Comput. Inf. Sci. Eng. 2012;12(4):041001-041001-10. doi:10.1115/1.4007401.

In the field of minimally invasive surgery (MIS), trainers based on virtual reality provide a very useful, nondegradable, realistic training environment. The project of building this new type of trainers requires the development of new tools. In this paper, we describe a set of new measures that allow calculating the optimal position and orientation of haptic devices versus the virtual workspace of the application. We illustrate the use of these new tools applying them to a practical application.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2012;12(4):041002-041002-12. doi:10.1115/1.4007403.

Current parametric CAD systems are based on solving equality types of constraints between geometric objects and parameters. This includes algebraic equations constraining the values of variables, and geometric constraints constraining the positions of geometric objects. However, to truly represent design intent, next-generation CAD systems must also allow users to input other types of constraints such as inequality constraints. Inequality constraints are expressed as inequality expressions on variables, or as geometric constraints that force geometric objects to be on specific sides or have specific orientations with respect to other objects. The research presented here investigates whether the frontier algorithm can be extended to solve geometry positioning problems involving systems of equality- and inequality-based declarations in which the inequality-based declarations are used as solution selectors to choose from multiple solutions inherently arising when solving these systems. It is found that these systems can be decomposed by the frontier algorithm in a manner similar to purely equality-based constraint systems, however they require tracking and iterating through multiple solutions and in many cases may require backtracking through the solution sequence. The computational complexity of the new algorithm is found to be the same as the frontier algorithm in the planning phase and linear in the execution phase with respect to the size of the problem but exponential with respect to the distance of solution selection steps from the satisfaction steps they control.

Topics: Algorithms
Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2012;12(4):041003-041003-7. doi:10.1115/1.4007447.

The use of the image space of planar displacements for planar motion approximation is a well studied subject. While the constraint manifolds associated with planar four-bar linkages are algebraic, geometric (or normal) distances have been used as default metric for nonlinear least squares fitting of these algebraic manifolds. This paper presents a new formulation for the manifold fitting problem using algebraic distance and shows that the problem can be solved by fitting a pencil of quadrics with linear coefficients to a set of image points of a given set of displacements. This linear formulation leads to a simple and fast algorithm for kinematic synthesis in the image space.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2012;12(4):041004-041004-10. doi:10.1115/1.4007404.

The geometric variations in a tolerance-zone can be modeled with hypothetical point-spaces called Tolerance-Maps (T-Maps) for purposes of automating the assignment of tolerances during design. The objective of this paper is to extend this model to represent tolerances on line-profiles. Such tolerances limit geometric manufacturing variations to a specified two-dimensional tolerance-zone, i.e., an area, the boundaries to which are curves parallel to the true profile. The single profile tolerance may be used to control position, orientation, and form of the profile. In this paper, the Tolerance-Map (Patent No. 6963824) is a hypothetical volume of points that captures all the positions for the true profile, and those curves parallel to it, which can reside in the tolerance-zone. The model is compatible with the ASME/ANSI/ISO Standards for geometric tolerances. T-Maps have been generated for other classes of geometric tolerances in which the variations of the feature are represented with a plane, line or circle, and these have been incorporated into testbed software for aiding designers when assigning tolerances for assemblies. In this paper the T-Map for line-profiles is created and, for the first time in this model, features may be either symmetrical or nonsymmetrical simple planar curves, typically closed. To economize on length of the paper, and yet to introduce a method whereby T-Maps may be used to optimize the allocation of tolerances for line-profiles, the scope of the paper has been limited to square, rectangular, and triangular shapes. An example of tolerance accumulation is presented to illustrate this method.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2012;12(4):041005-041005-14. doi:10.1115/1.4007765.

Design resources such as design tools, knowledge, and data play important roles in the product variant design. The requirements for these resources as well as the resource integration mechanisms are evolving along the life-cycle based product design process. It is expected by designers that not only right design resources but also appropriate integration methods can be found and applied timely to realize design variations efficiently and effectively. In this paper, a hybrid design resource integration framework is proposed based on the design process and resource modeling in order to satisfy the evolutionary requirements for design resources in the process. The integration framework is divided into two levels, namely the abstract integration of virtual resource classes into task templates in the design process modeling and the concrete integration of resource instances into design activities in the design project runs. Based on the two-level integration framework, a hybrid integration mechanism including flexible and stiff integration models and three integration transition methods is proposed to adapt to the from-abstract-to-concrete design evolution process. The system structure and behavior models are given, according to the analysis of integration framework. A hypo-pneumatic spring design case is used to demonstrate the utility of the hybrid integration system. Design results obtained based on the resource integration tool and the traditional manual design approach are compared to assess the tool performance, which shows substantive improvements of design efficiency and efficacy.

Topics: Design , Modeling , Mechanisms
Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2012;12(4):041006-041006-14. doi:10.1115/1.4007764.

In this paper, we present a framework for automated component sizing to extend a designer's ability to evaluate a particular configuration during the architecture exploration phase of a design process. Component sizing is a hard problem to solve, both from a computational and modeling aspect. This is because of competing objectives, requirements from multiple disciplines, and the need to find a good solution quickly for the architecture being considered. In current approaches, designers rely on heuristics and iterate over the multiple objectives and requirements until a satisfactory solution is found. To improve on this state of practice, we introduce advances in the following two areas: (a) solving the problem efficiently so that all of the imposed requirements are satisfied simultaneously and the solution obtained is mathematically optimal and (b) modeling a component sizing problem in a manner that is convenient to designers. An acausal, algebraic, equation-based, declarative modeling approach using mathematical programming (GAMS) is taken to solve these problems more efficiently. The object management group systems modeling language (OMG SysML™) is used to model component sizing problems in order to facilitate problem formulation, model reuse and automatic generation of low-level code that can be solved using GAMS and its solvers. This framework is demonstrated by applying it to an example of a hydraulic log splitter. Based on this initial example, we discuss two advantages of this framework—total time taken in solving multiple scenarios for a given configuration and the graphical representation of a problem in SysML.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2012;12(4):041007-041007-7. doi:10.1115/1.4007839.

When designing a product that needs to fit the human shape, designers often use a small set of 3D models, called design models, either in physical or digital form, as representative shapes to cover the shape variabilities of the population for which the products are designed. Until recently, the process of creating these models has been an art involving manual interaction and empirical guesswork. The availability of the 3D anthropometric databases provides an opportunity to create design models optimally. In this paper, we propose a novel way to use 3D anthropometric databases to generate design models that represent a given population for design applications such as the sizing of garments and gear. We generate the representative shapes by solving a covering problem in a parameter space. Well-known techniques in computational geometry are used to solve this problem. We demonstrate the method using examples in designing glasses and helmets.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2012;12(4):041008-041008-10. doi:10.1115/1.4007862.

A web-based architecture of an radio frequency identification (RFID) tracking solution is proposed and deployed. The architecture attempts to depart from the typical localized approach of most RFID middlewares. The middleware has been replaced by a web service residing in a cloud. The traditional roles of the middleware such as tag data filtering, sorting, storage, and event processing have been redistributed amongst an RFID reader-based application and the web service. This architecture provides more flexibility and control to large scale RFID-based supply chain operations which are global in nature and unsuitable to the traditional localized middleware-based architecture of RFID tracking solutions. The feasibility of the web-based architecture is further augmented by validating performance parameters such as tag processing and primitive and complex event processing delay. Different subarchitectures are also proposed based on performance data for different scales of operations.

Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2012;12(4):041009-041009-10. doi:10.1115/1.4007986.

Mechatronic design is traditionally supported through domain-specific design activities throughout the product development process. The partitioning into domain-specific problems leads to a situation where product properties influence each other, hence giving rise to dependencies. These dependencies play a key role in the prediction of properties and, as a result, in the decision-making process. The important question is how to manage the dependencies for efficient and effective decision making? The aim of this paper is threefold. First, we investigate the nature of dependencies and study how to model them. The paper proposes appropriate terminology taking into account the synthesis and analysis nature of both the properties and the dependencies. This terminology will be the core of the new dependency modeling language. The concepts related to dependency modeling are then illustrated through a simple robot design example, where the creation and importance of a dependency model are explained. Second, we study practical approaches for consistency management and model management in the presence of dependencies. Six levels-of-detail in modeling dependencies are presented; emphasizing that modeling at a higher level-of-detail ensures that more inconsistencies are avoided. Available languages such as OMG SysML™ are evaluated for a possible creation of the dependency models leading toward executable dependency networks. However, at present, SysML does not provide sufficiently rich language constructs to model dependencies. Third, we compare our dependency modeling approach to other state-of-the-art approaches such as dependency modeling with a design structure matrix (DSM), and highlight the benefits of the terminology proposed in this paper. We aim to convince the reader that there is substantial value in modeling dependencies explicitly, especially to avoid inconsistencies, which is not the current state of practice. However, an overall value from dependency modeling can only be obtained if the cost of creating the dependency model is reasonable. Issues such as human interaction/effort and model management through product lifecycle management (PLM) are discussed.

Topics: Robots , Design , Modeling , Networks
Commentary by Dr. Valentin Fuster
J. Comput. Inf. Sci. Eng. 2012;12(4):041010-041010-7. doi:10.1115/1.4007988.

The optimization of mixed-integer problems is a classic problem with many industrial and design applications. A number of algorithms exist for the numerical optimization of these problems, but the robust optimization of mixed-integer problems has been explored to a far lesser extent. We present here a general methodology for the robust optimization of mixed-integer problems using nonuniform rational B-spline (NURBs) based metamodels and graph theory concepts. The use of these techniques allows for a new and powerful definition of robustness along integer variables. In this work, we define robustness as an invariance in problem structure, as opposed to insensitivity in the dependent variables. The application of this approach is demonstrated on two test problems. We conclude with a performance analysis of our new approach, comparisons to existing approaches, and our views on the future development of this technique.

Commentary by Dr. Valentin Fuster

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