bluuebunny/crossref_metadata_2025 huggingface dataset:
Ball Bearing Fatigue and Wear Life Optimization Using Elastohydrodynamic and Genetic Algorithm
Authors: Abbas Mohamed H. , Youssef Ayman M. A. , Metwalli Sayed M.
Published: March 2011

The present work attempts to improve the performance of rolling element bearings through the increase of fatigue life and the reduction of bearing wear. The formulation is based on Elastohydrodynamic to maximize the realistically evaluated minimum film thickness without significant increase in viscous friction torque. Design vectors are reduced in the present study relative to previous studies as some variables are considered as dependent variables. Other design vectors are not considered as variables in the study due to machining accuracy. This paper presents a more viable method to solve the multi-objective optimization problem using genetic algorithms (GAs) to reduce the chances of getting trapped in local maximum or minimum. Using a utility function, optimal Pareto points are obtained by changing the weight coefficients. Specific weights can be used depending on the designer decision whether to increase fatigue and wear life, or decrease the power consumption.
Constraint-Based Limb Synthesis and Mobility-Change-Aimed Mechanism Construction
Authors: Gan Dongming , Dai Jian S. , Caldwell Darwin G.
Published: March 2011

Based on the newly invented reconfigurable Hooke joint which changes the joint property, this paper investigates synthesis of limbs using the new joint based on constraint analysis. The procedure of the limb synthesis is put forward to fully use the property of the new joint for generating the reconfigurable limbs. Further, the paper presents a way of synthesising the parallel mechanism with metamorphic characteristics by starting from the aim at mobility-change. This is then integrated into the forward-based limb synthesis. A general procedure is proposed and applied to construct two classes of metamorphic parallel mechanisms. Their topological configuration change is investigated by examining the constraint change stemming from the phase alteration of the reconfigurable Hooke joint.
Coordination of Complex Product Development Processes
Authors: Suss Samuel , Thomson Vincent
Published: March 2011

Product development processes of complex products are complex themselves and particularly difficult to plan and manage effectively. Although many organizations manage their product development processes by monitoring the status of documents that are created as deliverables, in fact the progress of the process is in large part based on the actual information flow which is required to develop the product and produce the documents. A vital element in making product development processes work well is the correct understanding of how information flows and how to facilitate its development. In this paper we describe an executable stochastic model of the product development process that incorporates the salient features of the interplay between the information development, exchange and progress of the technical work. Experiments with the model provide insight into the mechanisms that drive these complex processes.
Examining Interactions Between Solution Architecture and Designer Mistakes
Authors: Devendorf Erich , Lewis Kemper
Published: March 2011

When designing complex systems, it is often the case that a design process is subjected to a variety of unexpected inputs, interruptions, and changes. These disturbances can create unintended consequences including changes to the design process architecture, the planned design responsibilities, or the design objectives and requirements. In this paper a specific type of design disturbance, mistakes, is investigated. The impact of mistakes on the convergence time of a distributed multi-subsystem optimization problem is studied for several solution process architectures. A five subsystem case study is used to help understand the ability of certain architectures to handle the impact of the mistakes. These observations have led to the hypothesis that selecting distributed design architectures that minimize the number of iterations to propagate mistakes can significantly reduce their impact. It is also observed that design architectures that converge quickly tend to have these same error damping properties. Considering these observations when selecting distributed design architectures can passively reduce the impact of mistakes.
Exploring the Use of Category and Scale to Scope a Biological Functional Model
Authors: Nagel Jacquelyn K. S. , Stone Robert B. , McAdams Daniel A.
Published: March 2011

The natural world provides numerous cases for analogy and inspiration in engineering design. Biological organisms, phenomena and strategies, herein referred to as biological systems, are, in essence, living engineered systems. These living systems provide insight into sustainable and adaptable design and offer engineers billions of years of valuable experience, which can be used to inspire engineering innovation. This research presents a general method for functionally representing biological systems through systematic design techniques, affording conceptualization of biologically-inspired, engineering designs. Functional representation and abstraction techniques are utilized to translate biological systems into an engineering context. Thus, the biological system information is accessible to engineering designers with varying biological knowledge, but a common understanding of engineering design methods. Functional modeling is typically driven by customer needs or product re-designs; however, these cannot be applied to biological systems. Thus, we propose the use of biological category and scale to guide the design process. Mimicry categories and scales, in addition to answering a design question, aid the designer with defining boundaries or scope when developing a biological functional model. Biological category assists with framing the information in the right perspective, where as, biological scale deals with how much detail is required for an adequate representation of the biological system to utilize the information with a chosen engineering design method. In our case, the engineering design method is function-based design. Choosing a category serves to refine the boundary, but, like scale, its consideration might prompt the designer to consider the same biological system in a new and unique way leading to new ideas. General guidelines for modeling biological systems at varying scales and categories are given, along with two modeling examples.
Classification and Overview of Advanced Driver Assistance Systems According to the Driving Process
Authors: Rendon-Velez Elizabeth
Published: March 2011

In the field of automotive safety, Advanced Driver Assistance Systems (ADAS) that are systems designed to help the driver in its driver process, are receiving growing attention. Although the introduction of ADAS has contributed decreasing car accidents, the number of accidents is still high. This motivate us to explore the different available ADAS identifying the critical factors in order to find ways to enhance these systems. Some overviews and classifications of the ADAS field are available but the emphasis is more on the technical advances and the human machine interface rather than on the support they provide to the driver for the information processing. An overview and classification of the driver assistance systems field is presented with respect to that information processing performed by the driver when driving. The basic characteristics of these systems and the critical factors are provided. This approach allow for more appropriate identification of the priorities in the field of future research and development of ADAS regarding the driver. The proposed overview allocates the ADAS in 3 different categories on the basis of the sub process of driving they are helping (perception, analysis-decision, and action). This overview reveals that these systems besides being restricted by the sensors and the number of factors considered, they are specially limited in the consideration of drivers’ characteristics which is an important issue when human adaptation is considered.
Considering Secular and Demographic Trends in Designing for Present and Future Populations
Authors: de Vries Charlotte , Garneau Christopher J. , Nadadur Gopal , Parkinson Matthew B.
Published: March 2011

In products designed for human variability, the anthropometry (body measurements) of the target user population constitutes a primary source of variability that must be considered in the optimization of the spatial dimensions of the product. Accommodation, which describes the ability of a user to interact with a device or environment in their preferred manner, is a key measure of its performance. Other studies have considered various methods for accounting for the variability in anthropometry in a target user population to calculate estimated accommodation, but few have explicitly considered the effects of secular trends and demographic changes over time. This paper considers these changes in the context of a case study involving truck drivers and cab geometry. The truck driver populations are used to illustrate changes in body size and shape over a 30-year period and show how they affect user acceptability of designs. Changes in the gender split of the driver population are also considered, and are shown to have a significant effect on accommodation. The work demonstrates that secular trends and demographic changes over time significantly affect accommodation, but a well designed product will be more robust to these changes.
Analyses of Non-Kinematic Conical Roll Bending Process With Conical Rolls
Authors: Feng Zhengkun , Champliaud Henri
Published: March 2011

High quality cones can be successfully obtained in kinematic conical roll bending process due to the no-sliding between the conical rolls and the plate. However, the performance of the process is limited because the conical rolls cannot be reused to produce other cones with different size. For the purpose of reusing the existing conical rolls to reduce the manufacturing cost, an attachment is added to the top edge of the plate. In such configuration, the top side of the conical rolls slides over the plate to reduce the local velocity near the top edge. The appropriate velocity near the top edge of the plate makes it possible to roll the plate as using the kinematic conical roll bending process. This paper deals with the modeling and simulation of such non-kinematic conical roll bending process based on the finite element method. The numerical simulation results give the relation between the gap size of the bent cone and the friction at the plate/attachment contact. Well bent cones were obtained compared with the ideal cones.
Designing a Product Package Platform
Authors: Devendorf Margaret , Lewis Kemper
Published: March 2011

An essential part of designing a successful product family is establishing a recognizable, familiar, product family identity. It is very often the case that consumers first identify products based on their physical embodiment. The Apple iPod, DeWalt power tools, and KitchenAid appliances are all examples of product families that have successfully branded themselves based on physical principles. While physical branding is often the first trait apparent to designers, there are some products that cannot be differentiated based on physical appearance. This is especially common for consumable products. For example, it is impossible to differentiate between diet Coke, Classic Coke, and Pepsi when each is poured into separate glasses. When differentiation is difficult to achieve from a product’s physical characteristics, the product’s package becomes a vital part of establishing branding and communicating membership to a product family while maintaining individual product identity. In this paper, product packaging is investigated with a focus on the graphic packaging components that identify product families. These components include: color, shape, typography, and imagery. Through the application of tools used in facilities layout planning, graph theory, social network theory, and display design theory an approach to determine an optimal arrangement of graphic components is achieved. This approach is validated using a web based survey that tracks user-package interactions across a range of commonly used cereal boxes.
Development of a Microfluidic Mixer for Lab-on-a-Chip Applications With Active and Passive Actuations
Authors: Manoocheri Kasra , Du E.
Published: March 2011

Mixing of analytes and reagents is a critical and difficult step in lab-on-a-chip applications. This paper presents a hybrid approach for mixing two laminar aqueous streams in a microchannel. It consists of patterned geometric features and electrokinetic actuation along the channel for improved mixing performance. The mixer can potentially mix reagents in a fluid medium from deionized water to electrically conductive fluids (0.2 S m−1) with low voltage supplies (3.5 Vrms). The mixing capacity of this hybrid microfluidic mixer is characterized and compared with that of the separate passive and electrokinetic actuations.
The Tactile Exploration of a Harsh Environment by a Manipulator With Joint Backlash
Authors: Mazzini Francesco , Dubowsky Steven
Published: March 2011

Here the tactile exploration by an autonomous robot when its joints are corrupted by significant backlash is studied. The motivation is the exploration of junctions in oil wells where the harsh conditions dictate the use of tactile exploration. These conditions also result in large, unknown, and variable backlash in the manipulator’s transmissions. Here, a method is developed to simultaneously identify the backlash and map the unknown surface. The method only needs joint encoders, and avoids the use of delicate force or tactile sensors. The mapped surface is described as a combination of geometric primitives. The robot probes the surface in several locations with its tip and computes the contact point through direct kinematics. These contact points are used simultaneously to construct a map of the environment and to identify its joint backlash, improving the precision of the map. The effectiveness of the approach is demonstrated in both simulation case studies and laboratory experiments.
Stochastic Analysis of a Nonlinear MEMS Force Sensor
Authors: Hassanpour Pezhman A. , Nieva Patricia M. , Khajepour Amir
Published: March 2011

In this paper, a sensing technique, based on the detection of Hopf bifurcation in the dynamic of a micro-bridge, is proposed. The governing equations of motion are derived, which take into account the fringe and large deflection effects. Moreover, a stochastic analysis approach is proposed for investigating the reliability of the sensor readings. It has been demonstrated that sensitivity of more than 2mV/μN is achievable with this sensing technique.
Design Method Selection to Satisfy Consumer Variation: A Meta-Design Approach
Authors: Cormier Phillip , Lewis Kemper
Published: March 2011

Scientific fields typically have meta-heuristics that help scientists select appropriate modeling, analysis, or testing procedures based on problem parameters. For instance, the Reynolds number calculation dictates to fluid dynamicists the classification of the flow and subsequent modeling and analysis tools most appropriate to use. As engineering design matures into a field defined by scientific principles, there is a need for similar meta-heuristics to help designers select appropriate design tools and methods. There has been significant work developing design methods to support product development including robust design, product platforms, and reconfigurable design, among others. Many of these methods have matured into design paradigms but are still undergoing validation, exercise, and extension. However, when faced with a new product design (or re-design) problem, it is a challenging task to determine what methods or paradigms to subscribe to and implement; part of this decision involves whether to design a single product or a set of similar products (i.e., a product line). This is fundamentally a metadesign problem — the design of the design method. This paper proposes an approach to support this meta-design decision using market segmentation data and appropriate contextual information.
Synthesis of the Pitch Surfaces of Non-Circular Skew-Gears
Authors: Figliolini Giorgio , Rea Pierluigi , Angeles Jorge
Published: March 2011

The subject of this paper is the synthesis of the pitch surfaces of non-circular skew gears, intended to generate any motion program with a periodically varying transmission ratio. This is done by extending an existing algorithm, which was formulated through the application of dual algebra and the Principle of Transference. In particular, the variable transmission ratio of N-lobed elliptical and logarithmical cylindrical gears is expressed and analyzed along with their main characteristics to test the proposed algorithm, which is implemented in Matlab. The code generates the pitch surfaces of N-lobed elliptical and logarithmical skew gears, along with those of indexing skew gears. Finally, significant numerical and graphical results are shown to analyze the geometrical characteristics of the gear engagement. Not unexpectedly, cylindrical and bevel non-circular gears become particular cases thereof.
Medial Axis Transform of Planar Shapes With Free-Form Curve Boundary
Authors: Fu Qiang , Chen Zezhong C.
Published: March 2011

Medial axis transform (MAT) is a very useful shape interrogation tool in NC tool path generation for pocket milling. This paper presents a new, efficient approach to calculating MATs of planar profiles with boundaries of free-form curves. The proposed approach is mainly based on profile boundary tracing and decomposition. By studying the basic elements of MAT and their geometric properties, several algorithms of finding contact circles are developed. The boundary tracing algorithm can handle profiles with/without internal holes. For a profile without internal holes, it is continuously divided into simpler sub-profiles while travelling along the boundary, and a tree data structure is adopted to keep track of the boundary decomposition process. For a profile with internal holes, it is divided into several simple profiles without internal holes. After generating the MAT of each simple profile, the completed MAT can be found by combining these MATs. This proposed approach is implemented and some illustrative samples are presented to demonstrate its advantages.
Subdivision-Based 3D Remeshing With a Fast Spherical Parameterization Method
Authors: Zhang Ruqin , Winer Eliot , Oliver James H.
Published: March 2011

3D mesh parameterization is widely investigated with various parameter domains and applied in many computer graphics applications. As many surface meshes are manifolds of genus zero, mapping these meshes onto a topologically equivalent sphere provides some advantages. We introduce an efficient parameterization method based on barycentric embedding for this spherical domain. This method provides an overlapping solution which emphasizes on eliminating the vertex overlappings to ensure bijectivity. Experimental results indicate that it works faster than existing spherical parameterization methods. And we also provide a robust spherical remeshing algorithm based on spherical mesh subdivision. A local recursive subdivision process is employed to cover all the geometric details from the original mesh. Such subdivision process can be controlled to match the desired level of details (LOD), which will create a group of mesh representations with different resolutions. This multi-resolution remeshing framework could benefit various graphical applications including geometry rendering, mesh simplification/refinement, model morphing and etc.
Computing Constrained Laplacian Navigation Function Paths in Configuration Space
Authors: Johnson David E. , Martin Tobias , Cohen Elaine
Published: March 2011

This paper demonstrates path-planning for complex geometric models using harmonic function solutions to Laplace’s equation in the configuration space of the robot. The principal elements of the system are an approximate representation of the configuration space obstacles, finite element meshing of the free space, and Laplacian solutions to a path between start and end configurations in the free configuration space. Paths found by this system are smooth and free of local minima. Additionally, the full field solution can be used in novel ways to enforce constraints on the computed robot path, such as needed for car-like robots and in the presence of moving obstacles. The system is tested on several scenarios, such as a moving, rotating robot and a translating robot with moving obstacles, that demonstrate the generality of the approach.
Efficient, Accurate Geometric Modeling for Three-Axis Sculptured Surfaces Milling
Authors: Fu Qiang , Chen Zezhong C.
Published: March 2011

Efficient, accurate geometric modeling for three-axis sculptured surfaces milling is quite challenging due to complexity of workpiece geometry change during machining. This paper presents an efficient, accurate approach to extracting the cutter/workpiece engagement (CWE) geometry and applying this geometry to an existing mechanistic force model in order to predict instantaneous cutting force, torque and power. In our research, a basic geometric modeling of chip removal in three-axis milling is investigated, and an effective model is proposed to represent the cutter swept profile. Computationally efficient, closed-form formulations are derived for general APT (Automatically Programmed Tools) cutter geometry. A Z-level B-Rep model is adopted to represent the in-process workpiece model, and an innovative geometric approach is used to extract the CWE geometry. Then, a mechanistic cutting force model is integrated to predict the cutting forces. As a result, a milling process simulation system is developed for three-axis virtual milling of sculptured surfaces. The developed system is experimentally verified by comparing the simulation results with actual forces measured from machining a test surface.
Exploring Automated Concept Generator Output Through Principal Component Analysis
Authors: Poppa Kerry R. , Stone Robert B. , Orsborn Seth
Published: March 2011

During conceptual design it is desirable to produce many potential solutions. Recently, computational tools have emerged to help designers more fully explore possible solutions. These automated concept generators use knowledge from existing products and the desired functionality of the new design to suggest solutions. While research has shown these tools can increase the variety of solutions developed, they often provide unmanageably large sets of poorly differentiated results. This work proceeds from the hypothesis that automated concept generator output includes many permutations of a relatively few principal solution variants. A method to discover these underlying solution types from the initial concept generator output is proposed. The proposed method employs principal component analysis for variable reduction followed by cluster analysis for classification. The method is applied to the automatically generated solutions of three sample design problems. Preliminary evidence of the utility and efficiency of the proposed method is presented based upon those sample problems. Finally, a method for extending the proposed technique to much larger solution sets is discussed.
Establishing Relationships Between Manufacturing Sustainability and Performance
Authors: Johnson Matthew , Durham Delcie
Published: March 2011

The current LCA methods assess a product’s sustainability over its full life cycle, cradle-to-grave. While the number(s) obtained detail the contributions a process makes to a product in terms of energy intensity or the generation of wastes, it is insufficient to optimize a process for both sustainability and performance objectives. The Economic Input/Output Life Cycle Analysis (EIO-LCA) was used to investigate whether metrics could be identified which address sustainability — performance issues in materials processing. This method lends itself to the assessment of processes on a unit time basis while allowing for calculation of resources used and byproducts expelled. Productivity of manufacturing processes is also based on time. For example, material removal rate is related to processing feed, speed, and the geometry and tolerances established during design. A scaled waterjet cutting process was tested to investigate the unit time relationships. The EIO-LCA was conducted and the subsequent environmental impact in the form of total energy consumed and equivalent CO2 expelled evaluated per unit time, establishing the relationship to cutting speed. Although this is a static LCA at set conditions, it suggests that relationships can be explored between the regulation of resources, productivity, cost and environmental impact by varying the processing parameters.
The Mathematical Model of a Procedure for Percutaneous Annuloplasty
Authors: Azar Toufic , Angeles Jorge , Ko¨vecses Jozsef , Cecere Renzo
Published: March 2011

Existing mathematical models of the mitral valve allow the simulation of ring open-heart annuloplasty procedures intended to reduce the lumen of the valve. Using these models, only a posteriori effects can be predicted. With the advent of novel percutaneous annuloplasty approaches, there is a need to describe a priori effects; in particular, this paper focuses on a technique which consists of sequentially installing interconnected anchors around the mitral annulus, whose lumen is reduced by the tightening of the tethered wire. We develop here a static mathematical model of the mitral annulus that takes into account the mechanical response of its tissue and the surrounding muscular tissue. A number of roughly coplanar points corresponding to anchor positions, at about equal distantes, are identified on the annulus. Each of these points is then attached to a linearly elastic spring of a given stiffness, The spring-end is connected to a fixed pinned support, the other end supporting the wire, that forms a loop. With this model we estimate the anchor-points position vectors after lumen reduction and the wire tension that is needed to reduce the perimeter of the polygon defined by the anchor points to a given value, which, for each patient, is related to the desired lumen. This formulation leads to the minimization of the potential energy of the mechanical system over the position vectors of the anchor points after tightening, which are the design variables. These are found by solving the first-order normality conditions of the equality-constrained optimization problem. Preliminary experimental data obtained on cadaveric swine hearts validate the model: it can be used to predict, for a given perimeter size reduction, the wire tension as well as the anchor position after repair.
Complex Modal Extraction for Estimating Wave Parameters in One-Dimensional Media
Authors: Feeny B. F.
Published: March 2011

A method of complex orthogonal decomposition is applied to the extraction of modes from simulation data of multi-modal traveling waves in one-dimensional continua. The decomposition of a transient wave is performed on a nondispersive pulse. Complex wave modes are then extracted from a two-harmonic simulation of a dispersive medium. The wave frequencies and wave numbers are obtained by looking at the whirl of the complex modal coordinate, and the complex modal function, respectively, in the complex plane. From the frequencies and wave numbers, the wave speeds are then estimated, as well as the group velocity associated with the two waves. The group velocity is also extracted directly from a decomposition of the traveling envelope of the waveform. The observations from the first two examples are used to help interpret the decomposition of a simulation of the traveling waves produced by a Gaussian initial displacement profile in an Euler-Bernoulli beam. While such a disturbance produces a continuous spectrum of wave components, the sampling conditions limit the range of wave components (i.e. mode shapes and modal coordinates) to be extracted. Within this working range, the wave numbers and frequencies are obtained from the extraction, and compared to theory. The frequency distribution is then approximated. The results are robust to random noise.
Exploring Spatial Reasoning Ability and Design Cognition in Undergraduate Engineering Students
Authors: Williams Christopher B. , Gero John , Lee Yoon , Paretti Marie
Published: March 2011

This paper presents preliminary results from the first phase of a longitudinal study of design cognition and the effects of design education on design practice. The study aims to monitor the development of engineering design thinking through a three-year protocol study of control and experimental groups of engineering students. Using innovations in cognitive science that include ontologically-based coding of protocols and new methods of protocol analysis, the study is intended to characterize students’ cognitive development, identify differences over time, and relate those differences to students’ educational experiences. The first phase of this study focuses on assessing students’ spatial reasoning ability. Spatial reasoning is the ability to process and form ideas through spatial relationships among objects. It has been found to correlate strongly with the design ability associated with one’s ability to generate, conceptualize, and communicate solutions to problems. Sophomore students entering two different majors took four spatial reasoning tests (Paper Folding, Vandenberg, Mental Rotation, and Spatial Imagery Ability) that addressed their ability to visualize objects and mentally manipulate them over an ordered sequence of spatial transformations. The results of these tests are presented in this paper. Tests were conducted to determine statistical significance in order to evaluate whether a student’s spatial reasoning ability correlates with their choice of engineering major. The students’ test performances are also compared with existing data from other fields (e.g., architecture, visual arts, science, and humanities).
The Multi-Relationship Evaluation Design Framework: Designing Testing Plans to Comprehensively Assess Advanced and Intelligent Technologies
Authors: Weiss Brian A. , Schmidt Linda C. , Scott Harry A. , Schlenoff Craig I.
Published: March 2011

As new technologies develop and mature, it becomes critical to provide both formative and summative assessments on their performance. Performance assessment events range in form from a few simple tests of key elements of the technology to highly complex and extensive evaluation exercises targeting specific levels and capabilities of the system under scrutiny. Typically the more advanced the system, the more often performance evaluations are warranted, and the more complex the evaluation planning becomes. Numerous evaluation frameworks have been developed to generate evaluation designs intent on characterizing the performance of intelligent systems. Many of these frameworks enable the design of extensive evaluations, but each has its own focused objectives within an inherent set of known boundaries. This paper introduces the Multi-Relationship Evaluation Design (MRED) framework whose ultimate goal is to automatically generate an evaluation design based upon multiple inputs. The MRED framework takes input goal data and outputs an evaluation blueprint complete with specific evaluation elements including level of technology to be tested, metric type, user type, and, evaluation environment. Some of MRED’s unique features are that it characterizes these relationships and manages their uncertainties along with those associated with evaluation input. The authors will introduce MRED by first presenting relationships between four main evaluation design elements. These evaluation elements are defined and the relationships between them are established including the connections between evaluation personnel (not just the users), their level of knowledge, and decision-making authority. This will be further supported through the definition of key terms. An example will be presented in which these terms and relationships are applied to the evaluation design of an automobile technology. An initial validation step follows where MRED is applied to the speech translation technology whose evaluation design was inspired by the successful use of a pre-existing evaluation framework. It is important to note that MRED is still in its early stages of development where this paper presents numerous MRED outputs. Future publications will present the remaining outputs, the uncertain inputs, and MRED’s implementation steps that produce the detailed evaluation blueprints.
Static Analysis of Single-Input/Multiple-Output Tendon-Driven Underactuated Mechanisms for Robotic Hands
Authors: Baril Mathieu , Laliberte´ Thierry , Guay Franc¸ois , Gosselin Cle´ment
Published: March 2011

Considering the many advantages of underactuation in anthropomorphic hands, such as lightness, ease of control and compactness, it is of interest to develop mechanisms that aim at achieving underactuation between the fingers. This paper presents several tendon-driven underactuated mechanisms that can drive four outputs from one input. These mechanisms could typically be used to drive four fingers of an underactuated hand from a single input. Among these mechanisms, some are built by combining one-input/two-output differential mechanisms, while others are fully integrated systems of pulleys. For each mechanism, a static analysis is presented. Then, a discussion based on the static analysis and experimentation on models highlights their strengths and weaknesses. Finally a new anthropomorphic hand used as an experimental platform to test these mechanisms is introduced.
A Geometric Parametric Analysis of a Magnetorheological Engine Mount
Authors: Anderson Walter , Ciocanel Constantine , Elahinia Mohammad
Published: March 2011

Engine vibration has caused a great deal of research for isolation to be performed. Traditionally, isolation was achieved through the use of pure elastomeric (rubber) mounts. However, with advances in vehicle technology, these types of mounts have become inadequate. The inadequacy stems from the vibration profile associated with the engine, i.e. high displacement at low frequency and small displacement at high frequency. Ideal isolation would be achieved through a stiff mount for low frequency and a soft mount for high frequency. This is contradictory to the performance of the elastomeric mounts. Hydraulic mounts were then developed to address this problem. A hydraulic mount has variable stiffness and damping due to the use of a decoupler and an inertia track. However, further advances in vehicle technology have rendered these mounts inadequate as well. Examples of these advances are hybridization (electric and hydraulic) and cylinder on demand (VCM, MDS & ACC). With these technologies, the vibration excitation has a significantly different profile, occurs over a wide range of frequencies, and calls for a new technology that can address this need. Magnetorheological (MR) fluid is a smart material that is able to change viscosity in the presence of a magnetic field. With the use of MR fluid, variable damping and stiffness can be achieved. An MR mount has been developed and tested. The performance of the mount depends on the geometry of the rubber part as well as the behavior of the MR fluid. The rubber top of the mount is the topic of this study due to its major impact on the isolation characteristics of the MR mount. To develop a design methodology to address the isolation needs of different hybrid vehicles, a geometric parametric finite element analysis has been completed and presented in this paper.
Using Level Set Method in Order to Design Structures Against Buckling
Authors: Kasaiezadeh Alireza , Khajepour Amir , Jahed Hamid
Published: March 2011

The level set approach has been used as a powerful tool in designing structures with a proper safety margin against stability and buckling issues. In this article a closed form equation for critical buckling load of any arbitrary topology has been proposed and employed in Level Set formulation in order to maximize it. Results show that the Level Set Method is straight forward and easy to implement, with fewer limitations overall in the topology optimization of engineering structures.
An Enhanced Stability Model for Electrostatic Comb-Drive Actuator Design
Authors: Trutna Tristan T. , Awtar Shorya
Published: March 2011

This paper presents a stability model for predicting the snap-in behavior of electrostatic comb-drive actuators, while taking into account the bearing direction stiffness and error motion of the associated flexure suspension. Error motions typically arise from the flexure suspension kinematics or manufacturing variations. The presented model allows for a more accurate determination of the comb-drive actuator’s motion range, limited by snap-in instability, as well as robustness against this instability over the motion range. Ultimately, this model is used as an effective design tool to help evaluate several existing and new flexure suspension geometries for range and robustness.
Real Time HPC Architecture for Engineering Applications
Authors: Nelson Dawn , Spetka Scott
Published: March 2011

The need to increase the performance of real time systems is growing along with system complexity. High performance computers (HPCs) with real-time scheduling support can be used to control and improve the performance of real time engineering applications. The latency that develops when parallel programs finish at dissimilar times is referred to as jitter. Jitter and latency can develop due to interference by other processes, interrupt handlers, or the Linux operating system. Experiments that used the Real Time Application Interface (RTAI) in conjunction with the Message Passing Interface (MPI) to implement parallel applications, reduced or eliminated jitter for experimental codes that have characteristics typical of engineering applications. The experimental HPC test bed is a Linux cluster with nine Intel Pentium IV, 3.4 GHz computers, connected by 100 Mb Ethernet using a switch. Each Linux system has 1 GB main memory, and is running Linux release 2.6.23 patched with RTAI 3.6.
When to Transform? Development of Indicators for Design Context Evaluation
Authors: Camburn Bradley A. , Guillemette Jason , Crawford Richard H. , Wood Kristin L. , Jensen Dan J. , Wood John J.
Published: March 2011

Transformable products (or transformers), those with two or more functional states, are increasingly utilized by our society. As the mobility and complexity of life increases, so must the adaptability of the products which we use. To develop more adaptable products and systems, we need new design techniques. Transformer design methodology is a discipline with opportunity for expansive development. In particular, the question of deciding when a transformable design is applicable, is as yet unanswered by current research. The purpose of this study is to propose a response to the question “When to implement a transformable design approach?”, by developing and assessing a technical design method. Our novel method identifies, at an early stage in the design process, when developing a transformable product is likely to be advantageous. A brief review of how prior research efforts which categorize transformers has been included. This review helps define what a transformer is, and acts as a segue to understanding when to use transformational designs. Both a deductive and an inductive study are used to identify transformation indicators, primary context properties and usage factors that identify “When to transform?” Our technique seeks to enhance the process of design by simultaneously reducing process complexity and broadening the design scope. The result of this study is a set of basic transformation indicators. Two applications are provided for the use of these indicators: identification of whether transformation is a viable solution branch to a particular design problem statement; and simplified development of new transformers by functionally examining a usage environment or process.
Improving Engineering Design Education: From Skills to Educational Objectives
Authors: Vargas Hernandez Noe , Davila Rangel Gabriel
Published: March 2011

The objective of this paper is to propose an engineering design educational pedagogy on how to improve the engineering design skills. The design engineering activity is a complex mix of skills and knowledge that has been taught over decades by directly delivering to the students the design methodologies developed by design researchers and by exposing the students to open ended projects that can develop their design skills. From this we can conclude that the three main pedagogical components of a successful educational design experience are: the design skills, the design methods and the design projects. However the individual design skills must be properly developed in the student prior to the project experience and since this is generally not the case, makes it an overwhelming challenge for the student. We present an approach to design engineering teaching through four main steps: First, define the desired knowledge and skills to be acquired by the student during the learning process. Second, organize the skills to be acquired in complexity levels. Third, generate educational objectives for each of the skills. Although the scope of this paper stops here, the educational objectives can be transformed in educational tasks (i.e. lectures, problems, exams, etc.) by using educational theories (teaching styles, learning styles, etc.) in such a way that the student will be able to develop those skills. This model could serve initially as a diagnostic tool to characterize the current set of skills of a given design course or program. The model can also be used to implement educational tasks into the classroom and labs depending on the desired student profile.
Combining Mathematical Programming and SysML for Automated Component Sizing of Hydraulic Systems
Authors: Shah Aditya A. , Paredis Christiaan J. J. , Burkhart Roger , Schaefer Dirk
Published: March 2011

In this paper, we present a framework that improves a designer’s capability to determine near-optimal sizes of components for a given system architecture. Component sizing is a hard problem to solve because of competing objectives, requirements from multiple disciplines, and the need for finding a 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) Formulating a component sizing problem in a manner that is convenient to designers and b) Solving the problem efficiently so that all of the imposed requirements are satisfied simultaneously and the solution obtained is mathematically optimal. An acausal, algebraic, equation-based, declarative modeling approach using mathematical programming (GAMS) is taken to solve these problems more efficiently. In addition the Systems Modeling Language (OMG SysML™) is used to formulate component sizing problems to facilitate problem formulation, model reuse and the automatic generation of low-level code that can be solved using GAMS and its solvers (BARON). This framework is demonstrated by applying it to an example of a hydraulic log splitter.
Type Synthesis Principle and Practice of Flexure Systems in the Framework of Screw Theory: Part III—Numerations and Synthesis of Flexure Mechanisms
Authors: Li S. Z. , Yu J. J. , Pei X. , Su Hai-jun , Hopkins J. B. , Culpepper M. L.
Published: March 2011

In recent years, the increasing of application requirements call for development of a variety of flexure mechanisms with high precision or large motion and both. Therefore, in Part III of this series of papers we demonstrate how to use the methodology addressed in Part I to synthesize concepts for two kinds of flexure mechanisms, i.e. kinematics-type flexure mechanisms (KFMs) and constraint-type flexure mechanisms (CFMs) with the specified-DOF (Degree of Freedom) characteristics. Although most of them utilize parallel configurations and flexure elements, there is a clear difference in the behavior of flexures between KFMs and CFMs, The resultant type synthesis approaches fall into two distinct categories i.e. freedom-based and constraint-based one, both of which have presented in Part I. In order to derive useful flexure mechanism concepts available for different applications, a general design philosophy and rules are summarized firstly. As the main content of this part, the classifications, numerations, and synthesis for KFMs and CFMs are made in a systematic way. As a result, a majority of new precision flexure mechanisms are developed. In addition, qualitative comparisons are provided to demonstrate the performance and application differences between kinematic-type and constraint-type flexure mechanisms with the same DOF.
On Designing Structured Soft Covers for Robotic Limbs With Predetermined Compliance
Authors: Berselli Giovanni , Piccinini Marco , Vassura Gabriele
Published: March 2011

In order to overcome the limits due to the fact that homogeneous layers of soft material placed over robotic limbs behave differently with respect to biological models, this paper suggests the adoption of soft covers (pads) with differentiated structure. In particular, it is proposed to divide the allowable pad thickness into two layers: a continuous external layer (skin) and a discontinuous internal layer, so that the overall stiffness can be adjusted by properly shaping the discontinuous layer. The methodology adopted for designing the internal layer is composed of two steps. Firstly, the cover surface is conceptually split into finite elementary triangular sub-regions. Secondly, the internal layer of each triangular element is designed in order to replicate the shape of the non-linear compression law which is typical of endoskeletal structures covered by pulpy tissues. A series of symmetrically-disposed inclined micro-beams is used for the purpose. Once the compression law of each triangular element is known, the overall pad compliance can be modulated by correctly choosing the number and size of the elements composing the pad. Equipment and results of a combined experimental and numerical analysis (FEM) are presented. The results confirm that the proposed concept can be an effective solution when designing soft covers whose behavior need to match the compliance of the biological counterpart. As an example, artificial pads which mimic the human finger behavior are presented.