bluuebunny/crossref_metadata_2025 huggingface dataset:
Fold Bifurcation in the State-Dependent Delay Model of Milling: Analytical and Numerical Solutions
Authors: Bachrathy Daniel , Stepan Gabor
Published: June 2012

The standard models of the milling process describe the surface regeneration effect by a delay-differential equation with constant time delay. In this study, an improved two degree of freedom model is presented for milling process where the regenerative effect is described by an improved state dependent time delay model. The model contains exact nonlinear screen functions describing the entrance and exit positions of the cutting edges of the milling tool. This model is valid in case of large amplitude forced vibrations close to the near-resonant spindle speeds. The periodic motions of this nonlinear system are calculated by a shooting method. The stability calculation is based on the linearization of the state-dependent delay differential equation around these periodic solutions by means of the semi-discretization method. The results are validated by an advanced numerical time domain simulation where the chip thickness is calculated by means of Boolean algebra.
Prediction of Horseshoes Chaos in Active Magnetic Bearings With Time-Varying Stiffness
Authors: Kitio Kwuimy C. A. , Nataraj C.
Published: June 2012

The paper considers a model of an active magnetic bearing with time-varying stiffness and investigates the effects of the control gain parameters on the appearance of horseshoes chaos. The Melnikov method is used to derive the critical conditions for chaos and numerical simulations are performed to determine the basins of attraction. It is shown that the domain of chaotic motion strongly depends on the gain parameters and that this domain increases with the magnetic force and decrease with the static current. The controller frequency ω is found to be a key parameter and has a critical effect on the enlargement of the chaotic domain.
Random Field Characterization With Insufficient Data Sets for Probability Analysis and Design
Authors: Xi Zhimin , Jung Byung C. , Youn Byeng D.
Published: June 2012

Random field is a generalization of a stochastic field, of which randomness can be characterized as a function of spatial variables. Examples of the random field can often be found as a geometry, material, and process variation in engineering products and processes. It has been widely acknowledged that consideration of the random field is quite significant to accurately predict variability in system performances. However, current approaches for characterizing the random field can only be applied to the situation with sufficient random field data sets and are not suitable to most engineering problems where the data sets are insufficient. The contribution of this paper is to model the random field based on the insufficient data sets such that sufficient data sets can be simulated or generated according to the random field modeling. Therefore, available random field characterization approaches and probability analysis methods can be used for probability analysis and design of many engineering problems with the lack of random field data sets. The proposed random field modeling is composed of two technical components including: 1) a Bayesian updating approach using the Markov Chain Monte Carlo (MCMC) method for modeling the random field based on available random field data sets; and 2) a Bayesian Copula dependence modeling approach for modeling statistical dependence of random field realizations at different measurement locations. Three examples including a mathematical problem, a heat generation problem of the Lithium-ion battery, and a refrigerator assembly problem are used to demonstrate the effectiveness of the proposed approach.
Discovering Structure in Design Databases Through Functional and Surface Based Mapping
Authors: Fu Katherine , Cagan Jonathan , Kotovsky Kenneth , Wood Kristin
Published: June 2012

This work presents a methodology for discovering structure in design repository databases, toward the ultimate goal of stimulating designers through design-by-analogy. Using a Bayesian model combined with Latent Semantic Analysis for discovering structural form in data, an exploration of inherent structural forms, based on the content and similarity of design data, is undertaken to gain useful insights into the nature of the design space. In this work, the approach is applied to uncover structure in the U.S. patent database. More specifically, the functional content and surface content of the patents are processed and mapped separately, yielding structures that have the potential to develop a better understanding of the functional and surface similarity of patents. These results may provide a basis for automated discovery of cross domain analogy, among other implications for creating a computational design stimulation tool.
Conceptual Design of Freeform Surfaces From Unstructured Point Sets Using Neural Network Regression
Authors: Yumer Mehmet Ersin , Kara Levent Burak
Published: June 2012

This paper presents a new point set surfacing method that employs neural networks for regression. Our technique takes as input unstructured and possibly noisy point sets representing two-manifolds in R3. To facilitate parametrization, the set is first embedded in R2 using neighborhood preserving locally linear embedding. A neural network is then constructed and trained that learns a mapping between the embedded 2D parametric coordinates and the corresponding 3D space coordinates. The trained network is then used to generate a tessellation that spans the parametric space, thereby producing a surface in the original space. This approach enables the surfacing of noisy and non-uniformly distributed point sets, and can be applied to open or closed surfaces. We show the utility of the proposed method on a number of test models, as well as its application to freeform surface creation in virtual reality environments.
A Continuous Modulated Wave-Form Command Shaping for Damped Overhead Cranes
Authors: Alhazza Khaled A. , Al-Shehaima Asmahan H. , Masoud Ziyad N.
Published: June 2012

A new command-shaping control strategy for oscillation reduction of damped harmonic oscillators is derived and implemented on damped overhead cranes. The effect of damping on the shaper frequency and duration is investigated. The performance of the proposed simper is simulated numerically and compared with the classical double-step input-shaper for different system properties. It was shown that, the proposed wave-form command profiles are capable of eliminating the travel and residual oscillations for systems with different damping ratio. Further, unlike traditional impulse and step command shapers, the proposed command profiles have smoother intermediate acceleration, velocity, and displacement profile.
Definition and Evaluation of Modular Product Structures in the Context of Design for Assembly
Authors: Halfmann Niklas , Elstner Steffen , Krause Dieter
Published: June 2012

The determination of modular product structures requires a continuous evaluation of the measures taken. Modularization is an appropriate method for product structuring. It provides the opportunity of taking into account the requirements from different product life phases, such as the development, production or after-sales phase. The assembly, as an essential part of the production for the company, demands easy mountable products. Short lead times and flexible processes are the main requirements among others. The methodical procedure presented in this paper proposes the integrative representation of the product structure and its resulting assembly sequence in a single diagram. The developed tool provides the opportunity to perform structuring measures to the product and coincidently show the impact on the assembly process. For the evaluation the use of key figures is proposed. The relevant input for the calculation of these key figures is similarly extracted from the diagram. Conclusively, the procedure is applied to an example of aircraft interior development.
Nonlinear Transient Dynamics of Pendulum Torsional Vibration Absorbers
Authors: Monroe Ryan J. , Shaw Steven W.
Published: June 2012

This paper describes an analytical and experimental investigation of the transient dynamics of centrifugal pendulum vibration absorbers, which are used for reducing torsional vibrations in rotating machines. Recently these absorbers have been proposed for use in automotive engines, to aid with fuel saving technologies such as cylinder deactivation and torque converter lockup. In order for them to operate effectively with minimal mass, they must be designed to allow for large amplitude, nonlinear responses. In this paper we consider the transient dynamics of these absorbers, focusing on the response during startup. During these transient events the absorbers experience a beating type motion, resulting in overshoot of the absorber response before reaching steady state conditions. Using a perturbation analysis of the system equations of motion, an approximate analytical expression for nonlinear overshoot is derived, relating the overshoot to the system and excitation parameters. These predictive results are derived for a general class of absorbers, and are verified by simulations of the full equations of motion and by experiments using a fully instrumented spin rig. It is found that the overshoot for absorbers with softening nonlinearity, such as circular path absorbers, can be well over the 100% upper limit for a linear absorber, and can be as high as 173%. For absorbers with tautochronic paths, the overshoot remains quite close to that of the linearized system, even for large amplitudes. These results provide a useful tool for the design of absorbers to meet transient response specifications.
Shape and Topology Optimization With Medial Zones
Authors: Eftekharian Ata A. , Ilies¸ Horea T.
Published: June 2012

Shape optimization (with topological changes) has become a de facto standard approach for synthesizing new designs. Current approaches heavily rely on voxelized modifications of the initial domain, followed by heuristic reconstruction procedures that result in a detailed shape design. The initial domain is almost always conservatively estimated so that the design space spans a sufficiently large set of possible solutions. We propose a novel approach to shape optimization that exploits the geometric and topologic properties of medial zones and a new shape modification paradigm to synthesize shapes with topological guarantees. The medial zone is a ‘thick skeleton’ of the domain induced by prescribed boundary conditions, and represents an initial solution that is topologically valid. We modify such an initial solution by adding or subtracting ‘bubbles’ of material defined via prescribed shape functions. The proposed approach has many advantages in terms of topological guarantees, shape control, and computational cost, supports parametric optimization of free-form geometry, and can be implemented in any geometric representation that supports distance computations.
Efficient Solution of Maggi’s Equations
Authors: Garci´a de Jalo´n Javier , Callejo Alfonso , Hidalgo Andre´s F. , Gutie´rrez Mari´a D.
Published: June 2012

According to a recent paper by Laulusa and Bauchau [1], Maggi’s formulation is a simple and stable way to solve the dynamic equations of constrained multibody systems. Among the difficulties of Maggi’s formulation, Laulusa and Bauchau quoted the need for an appropriate choice (and change, when necessary) of independent coordinates, as well as the high cost of computing and updating the basis of the tangent null space of constraint equations. In this paper, index-1 Lagrange’s equations are first considered, including the not-so-rare case of having a singular mass matrix and redundant constraints. The existence and uniqueness of solution for acceleration vector and Lagrange multipliers vector is studied in a very simple way. Then, following Von Schwerin [2], Maggi’s formulation is described as the most efficient way (globally speaking) to solve these index-1 equations. Next, an improved double-step method, which implements the matrix transformations of Maggi’s formulation in an efficient way, is described. Finally, two large real-life examples are presented.
Reduced Order Model of Nanoelectromechanical Systems to Include Casimir Effect
Authors: Caruntu Dumitru I. , Zapata Roberto J. , Knecht Martin W.
Published: June 2012

This paper deals with electrostatically actuated nanoelectromechanical (NEMS) cantilever resonators. The dynamic behavior is described by a second order partial differential equation. The NEMS cantilever resonator device is actuatedby an AC voltage resulting in a vibrating motion of the cantilever. At nano scale, squeeze film damping, Casimir force, and fringing effects significantly influence the dynamic behavior or the cantilever beam. The second order partial differential equation is solved using the Reduced Order Model (ROM) method. The resulting time dependent second order differential equations system is then transformed into a first order differential equations system. Numerical simulations were conducted using Matlab solver ode15s.
Physical Interpretations of Mathematical Expressions, as a Potent Tool of Engineering
Authors: Yedidiah Shmariahu Sam
Published: June 2012

The presented study demonstrates the enormous potentials of translating mathematical expressions into their relevant physical meanings. In the past, such translations have proven capable of explaining the cause(s) of phenomena, which seemed to defy all principles of common sense. In other cases, they were able to rectify deeply rooted misconceptions, which haunted the engineers for many decades. Among others, they have revealed the need for revising everything what has been done in the last eight decades in relation to the head developed by an impeller. All the above conclusions are here supported by actual case histories from past experience. The discussions presented in this study relate directly to the design of centrifugal and other rotodynamic pumps. However, there exist strong indications, that such translations may prove equally useful also in other fields of engineering.
Rethinking Design: The Formal Integration of Engineering Innovation Into a Design Process
Authors: Naim Aziz M. , Lewis Kemper E.
Published: June 2012

Innovation has been a hallmark of progress throughout human history. There are many innovative products that have had a tremendous impact on mankind’s quality of life. As engineering design matures into a field defined by scientific principles, there is a need for guidelines to help the designer select and apply appropriate tools and methods to support the development of innovative products. There has been significant work developing design methods to support the development of innovative products. There has been significant work developing design methods to support the development of innovative products as well as to understand the characteristics of the innovative products. Many of these methods however present themselves as a unique solution to develop innovative products but fail to fully define innovation. Furthermore, few guidelines are provided to the designer as to when to use the available tools with respect to the market dynamics, making the use of these methods sometimes ineffective. With a general push for US companies to become increasingly more innovative, it is important more than ever to understand and situate innovation in design practices in order to promote successful and consistent development of innovative products. This paper proposes a set of new “innovation for engineers” guidelines that are defined and used along existing engineering design theory and cyberinfrastructure design tools in a design process.
On Usage Context of Hybrid Electric Vehicles in Choice Studies
Authors: He Lin , Chen Wei , Conzelmann Guenter
Published: June 2012

Considering usage context attributes in choice modeling has been shown to be important when product performance highly depends on the usage context. To build a reliable choice model, it is critical to first understand the relationship between usage context attributes and customer profile attributes, then to identify the market segmentation characterized by both sets of attributes, and finally to construct a choice model by integrating data from multiple sources. This is a complex procedure especially when a large number of customer attributes are potentially influential to the product choice. Using the hybrid electric vehicle (HEV) as an example, this paper presents a systematic procedure and the associated data analysis techniques for implementing each of the above steps. Usage context and customer profile attributes extracted from both National Household Travel Survey (NHTS) and Vehicle Quality Survey (VQS) data are first analyzed to understand the relationship between usage context attributes and customer profile attributes. Next the principal component analysis is utilized to identify the key characteristics of hybrid vehicle drivers, and to determine the market segmentations of HEV and the critical attributes to include in choice models. Before the two sets of data are combined for choice modeling, statistical analysis is used to test the compatibility of the two datasets. A pooled choice model created by incorporating usage context attributes illustrates the benefits of context-based choice modeling using data from multiple sources. Even though NHTS and VQS have been used in the literature to study transportation patterns and vehicle quality ratings, respectively, this work is the first to explore how they may be used together to benefit the study of customer preference for HEVs.
Development of a Control Method of a Walking Assistance Apparatus for the Elderly or Rehabilitants
Authors: Tanaka Eiichirou , Ikehara Tadaaki , Yusa Hirokazu , Sato Yusuke , Sakurai Tomohiro , Saegusa Shozo , Ito Kazuhisa , Yuge Louis
Published: June 2012

A prototype for a walking assistance apparatus for the elderly or rehabilitants of motor palsy patients was developed as a next-generation vehicle or movable neuro-rehabilitation training appliance, using a novel spatial parallel link mechanism and a bearing lift. The flat steps of the apparatus move in parallel with the ground; the apparatus can support entire leg alignment (including soles) and assist; walking behavior at ankle, knee and hip joints simultaneously. To respond to the variation of equipped person’s walking velocity, the length of stride and walking cycle while walking with wearing the apparatus were compensated by using walking ratio. Therefore the apparatus can be controlled in response to equipped person’s will. Next, we developed a control method of the apparatus by using impedance control, taking into account the dynamics of the apparatus and the legs of an equipped person, and assist ratio for the equipped person. By adjusting the value of natural angular frequency of the desired dynamic equation for the equipped person, this apparatus can assist walking according to the equipped person’s desired response of the apparatus. Furthermore, motor palsy and muscle weakness patients can walk by themselves by using the apparatus; patients who have ambulation difficulty can use the apparatus with weight bearing lift that we developed. Using the apparatus with the weight bearing lift prevents stumbling and enables input of walking movement to the brain motor area. From the results of measured %MVC, the validity of the weight bearing lift was shown.
Evaluating Genetic Algorithms on Welding Sequence Optimization With Respect to Dimensional Variation and Cycle Time
Authors: Segeborn Johan , Carlson Johan S. , Wa¨rmefjord Kristina , So¨derberg Rikard
Published: June 2012

Spot welding is the predominant joining method in car body assembly. Spot welding sequences have a significant influence on the dimensional variation of resulting assemblies and ultimately on overall product quality. It also has a significant influence on welding robot cycle time and thus ultimately on manufacturing cost. In this work we evaluate the performance of Genetic Algorithms, GAs, on multi-criteria optimization of welding sequence with respect to dimensional assembly variation and welding robot cycle time. Reference assemblies are fully modelled in 3D including detailed fixtures, welding robots and weld guns. Dimensional variation is obtained using variation simulation and part measurement data. Cycle time is obtained using automatic robot path planning. GAs are not guaranteed to find the global optimum. Besides exhaustive calculations, there is no way to determine how close to the actual optimum a GA trial has reached. Furthermore, sequence fitness evaluations constitute the absolute majority of optimization computation running time and do thus need to be kept to a minimum. Therefore, for two industrial reference assemblies we investigate the number of fitness evaluations that is required to find a sequence that is optimal or a near-optimal with respect to the fitness function. The fitness function in this work is a single criterion based on a weighted and normalized combination of dimensional variation and cycle time. Both reference assemblies involves 7 spot welds which entails 7!=5040 possible welding sequences. For both reference assemblies, dimensional variation and cycle time is exhaustively calculated for all 5040 possible sequences, determining the optimal sequence, with respect to the fitness function, for a fact. Then a GA that utilizes Random Key Encoding is applied on both cases and the performance is recorded. It is found that in searching through about 1% of the possible sequences, optimum is reached in about half of the trials and 80–90% of the trials reach the ten best sequences. Furthermore the optimum of the single criterion fitness function entails dimensional variation and cycle time fairly close to their respective optimum. In conclusion, this work indicates that genetic algorithms are highly effective in optimizing welding sequence with respect to dimensional variation and cycle time.
Command-Shaping Control System for Double-Pendulum Gantry Cranes
Authors: Masoud Ziyad N. , Alhazza Khaled A.
Published: June 2012

Traditionally, multi-mode command-shaping controllers are tuned to the system frequencies. This work suggests an opposite approach. A frequency-modulation (FM) strategy is developed to tune the system frequencies to match the frequencies eliminated by a single-mode command-shaper. The shaper developed in this work is based on a double-step command-shaping strategy. Using the FM Shaper, a simulated feedback system is used to modulate the closed-loop frequencies of a simulated double-pendulum model to the point where the closed-loop second mode frequency becomes an odd multiple of the closed-loop first mode frequency, which is the necessary condition for a satisfactory performance of a single-mode command-shaper. The double-step command-shaper is based on the closed-loop first mode frequency. The input commands to the plant of the simulated closed-loop system are then used to drive the actual double-pendulum. Performance is validated experimentally on a scaled model of a double-pendulum gantry crane.
Parametric Vehicular Simulator in the Evaluation of HELVIS Mini-HEV EDS Control
Authors: Sampaio Rafael C. B. , de Lima Gabriel S. , Fernandes Vinicius V. M. , Hernandes Andre´ C. , Becker Marcelo
Published: June 2012

HELVIS (Hybrid Electric Vehicle In Low Scale) is a mini-HEV platform used on the research of HEVs (Hybrid Electric Vehicles), through which students of all degrees have the opportunity to be introduced to the universe that surrounds HEVs in many aspects. In this work the HELVIS-Sim is presented. HELVIS-Sim is a full dynamic & kinematic vehicular simulator for the HELVIS platform, consisting of a Simulink™ environment through which the states of a large number of variables related to the vehicle can be observed and analyzed. Specially in this paper, the focus is in the control of HELVIS EDS (Electronic Differential System), presenting classic, A.I.-based (Artificial Intelligence) and optimal robust controllers in the problem of the adjustment of the rear angular speeds. HELVIS-Sim results are then compared to experimental data obtained from the real HELVIS EDS, with the aid of a dSpace™ real time interface board.
Identifying Product Scaling Principles: A Tool for Bioinspired Design and Beyond
Authors: Perez Angel G. , Linsey Julie S.
Published: June 2012

There are countless products that perform the same function but are engineered to suit a different scale. Designers are often faced with the problem of taking a solution at one scale and mapping it to another. This frequently happens with design-by-analogy and bioinspired design. Despite various scaling laws for specific systems, there are no global principles for scaling systems, for example from a biological nano-scale to macro-scale. This is likely one of the reasons bioinspired design is difficult. Very often scaling laws assume the same physical principles are being used, but this study of products indicates that a variety of changes occur as scale changes, including changing the physical principles to meet a particular function. Empirical product research was used to determine a set of principles by observing and understanding numerous products to unearth new generalizations. The function a product performs is examined in various scales to view subtle and blatant differences. Principles are then determined. This study provides an initial step in creating new innovative designs based on existing solutions in nature or other products that occur at very different scales. Much further work is needed by studying additional products and bioinspired examples.
Development of a Full-Sized Bipedal Humanoid Robot Utilizing Spring Assisted Parallel Four-Bar Linkages With Synchronized Actuation
Authors: Han Jeakweon , Hong Dennis
Published: June 2012

Besides the difficulties in control and gait generation, designing a full-sized (taller than 1.3m) bipedal humanoid robot that can walk with two legs is a very challenging task, mainly due to the large torque requirements at the joints combined with the need for the actuators’ size and weight to be small. Most of the handful of successful humanoid robots in this size class that exist today utilize harmonic drives for gear reduction to gain high torque in a compact package. However, this makes the cost of such a robot too high and thus puts it out of reach of most of those who want to use it for general research, education and outreach activities. Besides the cost, the heavy weight of the robot also causes difficulties in handling and raises concerns for safety. In this paper we present the design of a new class of full-sized bipedal humanoid robots that is lightweight and low cost. This is achieved by utilizing spring assisted parallel four-bar linkages with synchronized actuation in the lower body to reduce the torque requirements of the individual actuators which also enables the use of off the shelf components to further reduce the cost significantly. The resulting savings in weight not only makes the operation of the robot safer, but also allows it to forgo the expensive force/torque sensors at the ankles and achieve stable bipedal walking only using the feedback from the IMU (Inertial Measurement Unit.) CHARLI-L (Cognitive Humanoid Autonomous Robot with Learning Intelligence - Lightweight) is developed using this approach and successfully demonstrated untethered bipedal locomotion using ZMP (Zero Moment Point) based control, stable omnidirectional gaits, and carrying out tasks autonomously using vision based localization.
Mechanix: A Sketch Recognition Truss Tutoring System
Authors: Atilola Olufunmilola , Field Martin , McTigue Erin , Hammond Tracy , Linsey Julie
Published: June 2012

Mechanix is a sketch recogniton tool that provides an efficient means for engineering students to learn how to draw truss free-body diagrams (FBDs) and solve truss problems. The system allows students to sketch these FBDs into a tablet computer or by using a mouse just as they would by hand. Mechanix is then able to provide immediate feedback to the students and tells them if they are missing any components of the FBD, without providing answers. The program is also able to tell them whether their solved reaction or member forces are correct or not. This paper presents studies to evaluate the effectiveness and advantages of using Mechanix in the classroom, as a supplement to traditional teaching and learning methods. Current results demonstrate that students believe Mechanix enhances their learning and are highly engaged when using it. Future work on the refinement of the program is also discussed.
Sensitivity Analysis of Mobile Robots for Unstructured Environments
Authors: Ghotbi Bahareh , Azimi Ali , Ko¨vecses Jozsef , Angeles Jorge
Published: June 2012

Simulating mobile robots in unstructured environments requires knowledge of the wheel/terrain interaction phenomena. Even assuming that the terramechanics models available accurately represent the physics of the interaction, estimation of soil parameters can be a source of error. In applications where high robot reliability is mandatory, it is important to realize the influence of possible sources of error on the system behavior. The effect of small variations of parameters on system performance can be studied under sensitivity analysis. In this work, sensitivity analysis is conducted to investigate the effect of perturbations in the soil parameters on the behavior of a single rigid wheel and a vehicle on soft terrain. For the first system the two widely used terramechanics models, Bekker’s and Wong and Reace’s are studied, sensitivity analysis being conducted using direct differentiation. The second system is modeled using Bekker model, sensitivity being obtained using finite differences.
The Status of Design for Sustainability in Mechanical Engineering Design Education
Authors: Mountain Jeffrey R.
Published: June 2012

Sustainability is gaining national and global prominence as a key external constraint in engineering design. Courses in solar energy and wind energy have been common offerings, but due to their power production focus, do not address sustainability in the broader context of design. The question becomes, are undergraduate mechanical engineering programs evolving to introduce design for sustainability concepts, such as life cycle assessment, the triple bottom line, and carbon balance, in the broader context of mechanical engineering design? A review of mechanical engineering programs at well recognized universities indicates that most course offerings with definable sustainable design content remain focused on sustainable energy production. In addition, most of these courses are primarily graduate level offerings, indicating a substantial population of recent graduate engineers with limited knowledge of the scope of design for sustainability. Isolated efforts to broaden awareness of sustainability concepts were also identified and will be reported. These programs may serve as models for integration of sustainability into the general mechanical design education.
Identifying Enablers and Barriers to Successful Platform-Based Product Development: A Case Study From Business-to-Business Products
Authors: Jorgensen Jens , Havens David , Salvatore Paul , Rojas Arciniegas Alvaro J. , Esterman Marcos
Published: June 2012

Product development teams are facing continued pressure to develop more products in less time and with fewer resources. Platform-based developed is commonly seen as a solution to increase capacity of the product development pipeline. This research identified enablers and barriers to successful platform-based product development. This was achieved through a comprehensive literature review of the current state of the art and an exploratory case study of product development practices within a business-to-business environment from companies with significantly different cultures and experiences with platform-based product development. Key enablers identified in this research include institutionalizing systems engineering, development and communication of product development roadmaps, augmentation of phase gate review process and critical parameter characterization. Operational recommendations from this research are considered to be possible to implement without significant changes to existing processes and organizational structures.
Multi-Functional Surgical Robot for Laparo-Endoscopic Single-Site Colectomies
Authors: Wortman T. D. , McCormick R. L. , Markvicka E. J. , Frederick T. P. , Farritor S. M. , Oleynikov D.
Published: June 2012

This paper presents work to develop a miniature in vivo robot for Laparo-Endoscopic Single-Site (LESS) colectomy. Colon resections are generally not done laparoscopically and would benefit from a robotic platform that reduces the limitations that are currently encountered. This paper looks at the workspace, forces, and speeds of a recently developed miniature in vivo surgical robot platform and analyzes the ability to perform a colon resection based on these criteria. The robotic platform used in this study consists of a two armed robotic prototype and a remote surgeon interface. For the surgical procedure, each arm of the robot is inserted individually into a single five centimeter incision and then assembled within the abdominal cavity. A surgeon then utilizes a user interface that is remotely located within the operating room. The current robotic platform has recently been demonstrated successfully in an in vivo procedure.
Compliant Mechanism Design Using a Strain Based Topology Optimization Method
Authors: Liu Xiaobao , Lee Euihark , Gea Hae Chang , Du Ping An
Published: June 2012

Energy based topology optimization method has been used in the design of compliant mechanisms for many years. Although many successful examples from the energy based topology optimization have been presented, optimized configurations of these designs are often very similar to their rigid linkage counterparts except using compliant joints in place of rigid links. It is obvious that these complaint joints will endure large deformations under the applied forces in order to perform the specified motions and the large deformation will produce high stress which is very undesirable in compliant mechanism design. In this paper, a strain based topology optimization method is proposed to avoid localized high deformation design which is one of the drawbacks using strain energy formulation. Therefore, instead of minimizing the strain energy for structural rigidity, a global effective strain functional is minimized in order to distribute the deformation within the entire mechanism while maximizing the structural rigidity. Furthermore, the physical programming method is adopted to accommodate both flexibility and rigidity design objectives. Comparisons of design examples from both the strain energy based topology optimization and the strain based method are presented and discussed.
On the Spatial Modeling of a Vibratory Micro-Pin Feeder Using Rigid-Body Dynamics
Authors: Rimai Benjamin E. , Cipra Raymond J.
Published: June 2012

The use of micro-scale metallic pins in small engineering devices poses numerous problems due to their physical size and the dominant forces which act on micro-scale objects. Assembly and handling of devices with micro-scale parts is problematic because the components are below the threshold of practical, unaided human manipulation and most robotic manipulation. Previous experimental work has shown that applying forced vibrations to unsorted batches of micro-scale objects can order and singulate the objects or produce assemblies of several parts. Planar rigid-body dynamic simulations, which have been previously developed, lack the accuracy necessary for a-priori prediction of the performance of these processes. This paper presents a spatial simulation, based on an impulse-momentum rigid-body model, which more accurately predicts the behavior of micro-pins in a vibratory feeder bowl. The validity of the spatial simulation is verified by improved agreement with previously obtained experimental data.
A Programming Language Approach to Parametric CAD Data Exchange
Authors: Altidor John , Wileden Jack , McPherson Jeffrey , Grosse Ian , Krishnamurty Sundar , Cordeiro Felicia , Lee-St. John Audrey
Published: June 2012

Data exchange between different computer-aided design (CAD) systems is a major problem inhibiting information integration in collaborative engineering environments. Existing CAD data format standards such as STEP and IGES enable geometric data exchange. However, they ignore construction history, features, constraints, and other parametric-based CAD data. As a result, they are inadequate for supporting modification, extension and other important higher-level functionality when accessing an imported CAD model from another CAD system. Achieving such higher-level functionality therefore often requires a time-consuming, error-prone, tedious process of manually recreating the model in the target CAD system. Based on techniques adapted from programming language research, this paper presents an approach to exchanging parametric data between CAD systems using formally-defined conversion semantics. We have demonstrated the utility of our approach by developing a prototype implementation that automates the conversion of 2D sketches between two popular CAD systems: Pro/ENGINEER and SolidWorks. We present examples showing that our approach is able to accurately convert parametric CAD data even in cases where models were constructed using operations from the source CAD system that have no direct counterpart in the target CAD system. Although the case study focuses on 2D interoperability, our approach provides formal foundations for supporting 3D and semantic interoperability between CAD systems.
Sustainable Vehicle Design for Transportation System: A Technical and Social System of System Based Approach
Authors: Ali-Qureshi Zulfiqar
Published: June 2012

Sustainable life cycle based vehicle design has many perspectives. It holds a socio technical system based aspect and approaches for future development of automobile Industry. In this paper an Axiomatic design theory based approach is presented to find out the sustainable solutions for ongoing debate with regards to the self sustaining solutions of different nature for electric car. In this context the wind turbine and as well as the fuel cell technology are the top most contenders. The author has tried to demonstrate the technical system level aspect and social dynamics of the system which needed to be develop and shape the future of transportation industry.
Ontology-Based Representation and Verification to Enable Feature Interoperability Between CAD Systems
Authors: Tessier Sean , Wang Yan
Published: June 2012

Data interoperability between computer-aided design (CAD) systems remains a major obstacle in the information integration and exchange in a collaborative engineering environment. The standards for CAD data exchange have remained largely restricted to geometric representations, causing the design intent portrayed through construction history, features, parameters, and constraints to be discarded in the exchange process. In this research paper, an ontology-based framework is proposed to allow for the full exchange of semantic feature data. The Ontology Web Language (OWL) is used to represent feature types as well as the concepts and properties that define features, which allows the use of existing ontology reasoning tools to infer new relationships and information between heterogeneous data. Boundary representation (B-Rep) data corresponding to the output of the feature operation is also stored for purposes of feature identification and translation verification. The base ontology and a small feature library are built in OWL, and a combination of OWL and SWRL (Semantic Web Rule Language) rules are developed to allow a feature from an arbitrary source system to be automatically classified and translated into the target system through the use of a reasoner. These rules relate input parameter and reference types to expected B-Rep objects, allowing classification even when feature definitions vary or when little is known about the source system. In cases when the source system is well known, this approach also permits direct translation rules to be implemented. With such a flexible framework, a neutral feature exchange format could be developed.
Two-Directional Switching of Bistable Curved Micro Beams by Fringing Electrostatic Fields
Authors: Krylov Slava , Ilic Bojan R. , Lulinsky S.
Published: June 2012

In this work we investigate the feasibility of two-directional switching of a pre-buckled electrostatically actuated micro beam operated by a single electrode fabricated from the same structural layer. The distributed electrostatic force, which is engendered by the asymmetry of the fringing fields in the deformed state, acts in the direction opposite to the deflection of the beam and is of a restoring nature. The reduced order model was built using the Galerkin decomposition and verified using the results of the numerical solution of the differential equation. The actuating force was approximated by fitting the results of the numerical solution of the electrostatic problem. Static stability analysis reveals that the presence of the restoring electrostatic force may result in the suppression of the snap-through instability. We show that two-directional switching of a pre-buckled beam between two stable configurations and bistability cannot be achieved using quasistatic loading but are possible through dynamic instability mechanism. We demonstrate that switching associated with the dynamic snap-through takes place within certain interval of actuation voltages and pulse durations. Theoretical results illustrate the feasibility of the suggested operational principle as an efficient mechanism with application to nonvolatile mechanical memory devices.
An Accurate Spatial Discretization and Substructural Method With Application to Moving Elevator Cable-Car Systems: Part I—Methodology
Authors: Ren H. , Zhu W. D.
Published: June 2012

A spatial discretization and substructure method is developed to calculate the dynamic responses of one-dimensional systems, which consist of length-variant distributed-parameter components such as strings, rods, and beams, and lumped-parameter components such as point masses and rigid bodies. The dependent variable, such as the displacement, of a distributed-parameter component is decomposed into boundary-induced terms and internal terms. The boundary-induced terms are interpolated from the boundary motions, and the internal terms are approximated by an expansion of trial functions that satisfy the corresponding homogeneous boundary conditions. All the matching conditions at the interfaces of the components are satisfied, and the expansions of the dependent variables of the distributed-parameter components absolutely and uniformly converge. The spatial derivatives of the dependent variables, which are related to the internal forces/moments, such as the axial forces, bending moments, and shear forces, can be accurately calculated. Assembling the component equations and the geometric matching conditions that arise from the continuity relations leads to a system of differential algebraic equations (DAEs). When some matching conditions are linear algebraic equations, some generalized coordinates can be represented by others so that the number of the generalized coordinates can be reduced. The methodology is applied to moving elevator cable-car systems in Part II of this work.
Dynamics of Multibody Haptic Systems
Authors: Shayan Amin Sara , Ko¨vecses Jo´zsef
Published: June 2012

An essential requirement in haptics is accuracy and transparency of the haptic interface. Haptic devices are usually lightweight robotic systems with which a human operator interacts. In the current literature, dynamic analyses of haptic devices are limited to single degree-of-freedom (DoF) point mass models. In this paper, experimental and simulation studies are conducted to investigate the effects of mechanical design parameters on the performance of such devices. For this purpose two commonly used haptic devices were considered: a two-DoF PANTOGRAPH and a three-DoF PHANToM. The results show that dynamic coupling between the rendered (controlled) and free directions of motion can influence the desired performance. An alternative formulation is outlined in which dynamic behavior of a haptic interface is modeled as a multibody system. The dynamic equations are separated to two sets of equations associated with the rendered and admissible motions. Effects of time delay and discretization stemming from digital realization of the virtual environment can be analyzed using the rendered dynamic equations, while the equations associated with the admissible motions can serve as a basis for performance measure. This formulation can be efficiently used for the complex nonlinear dynamics and stability analyses of haptic interfaces and can provide essential details on the performance of these devices. Stability analysis of a two-DoF five-bar linkage is presented as an example using the proposed formulation.
Influence of Nonlinear Friction and Disturbance in the Control of a Mechatronic System: CNC Machine Tool Application
Authors: Rincon Liz K. , Rosario Joa˜o M.
Published: June 2012

The CNC (Computer Numerical Control) machine tools are complex mechatronic systems applied to the manufacture with high precision and high speeds. To achieve high accuracy and operational efficiency, the disturbance and friction, which occur during machining process, should be reduced as low as possible. This paper develops an analysis of influence by cutting force and friction effect in the control of machine tool based on the CNC dynamic model and parameters identification. For this purpose, the study focuses on Coulomb and Viscous nonlinear friction and the external disturbances. The analysis uses control position error, contour error, and stability to determine the influence of friction and disturbance. The results show that Viscous friction has more critical influence on system than the Cutting force and Coulomb. The work contributes in recognizing which parameters have greater influence on the machine behavior through dynamic analysis with the identification strategy, in order to design and improve the control structure for a real CNC system.
Nonlinear Dynamic Simulation of Hypoid Gearbox With Elastic Housing
Authors: Yang Junyi , Lim Teik C.
Published: June 2012

A methodology to predict the nonlinear dynamic response of hypoid gearboxes with elastic housing structure is proposed. The dynamic substructure strategy is applied to assemble the hypoid gear pair, shaft-bearing assembly and elastic housing models. The pinion and gear are modeled as rigid bodies with backlash nonlinearity and time-varying mesh coupling. The kinematic transmission error is assumed to be the excitation. The shaft-bearing assemblies are condensed using the finite element technique as stiffness matrices to support the pinion and gear. A lumped parameter representation of the elastic housing is established by applying the modal parameters extracted from an appropriate set of frequency response functions. In order to obtain the rotational coordinates, a rigid body interpolation of the translational responses at the bearing locations on the housing structure is applied. To demonstrate the salient features of the proposed methodology, a practical application is studied to analyze the effect of housing flexibility on the dynamic mesh force, and the effect of external excitation exerted on the housing on the dynamic mesh force and housing surface vibration. The parametric analysis reveals the sensitivity of dynamic mesh force to housing flexibility. Finally, the effect of external force exerted on the housing on gear dynamic responses can be significant and also appears to be location dependent.