bluuebunny/crossref_metadata_2025 huggingface dataset:
An Automated Design Synthesis Method for Compliant Mechanisms With Application to Morphing Wings
Authors: Wang Hongqing Vincent , Rosen David W.
Published: June 2008

An automated design synthesis method is developed to design an airfoil with a reconfigurable shape, which can change from one type of geometry to another. A design synthesis method using unit truss approach and particle swarm optimization is presented. In the unit truss approach, unit truss is used as a new unit cell for mechanics analysis of cellular structures, including lightweight structures and compliant mechanisms. Using unit truss approach, axial forces, bending, torsion, nonlinearity, and buckling in structures can be considered. It provides good analysis accuracy and computational efficiency. A synthesis method using unit truss approach integrated with particle swarm optimization is developed to systematically design adaptive cellular structures, in particular, compliant mechanisms discussed in this paper. As an example study, the authors realize the design synthesis of a compliant mechanism that enables an entire closed-loop airfoil profile to change shape from NACA 23015 to FX60-126 for the desired morphing wing. The nonlinear behavior of compliant mechanisms under large deformation is considered. The resulting design is validated by testing its robustness and considering nonlinearity.
Use of IRID (InfraRed IDentification) for Mobile Robot Localization
Authors: Bae Jungyun , Lee Sooyong
Published: June 2008

This paper presents mobile robot localization using IRID (InfraRed IDentification) as artificial landmarks. IRID is implemented with IR LEDs and photo transistors. Different from RFID, IRID has highly deterministic characteristics. By putting several IRID LEDs on the ceiling, the floor is divided into several sectors and each sector is set to have a unique identification. IRID tells which sector the robot is in, but the size of the uncertainty is still too large because the sector size is too large. This paper presents an algorithm which combines both the encoder and the IRID information so that the size of the uncertainty becomes smaller. It also introduces a framework which can be used with other types of the artificial landmarks. The characteristics of the developed IRID and the proposed algorithm are verified from the experiments.
Fast Layered Manufacturing Support Volume Computation on GPUs
Authors: Khardekar Rahul , McMains Sara
Published: June 2008

We present a GPU-accelerated algorithm for computing a fast approximation of the volume of supports required for layered manufacturing in a given build direction, one criterion often used to choose a direction that requires less time and material. In a sequence of rendering passes that project the part in the given build direction, we use depth peeling to identify faces bounding supports. We exploit programmable graphics hardware to compute the total height of all supports at each projected pixel location, scale the values by pixel area, and finally sum over all pixels to find the total volume of supports. For sample parts tested, our algorithm achieves over 99% accuracy and running times ranging from .2 seconds, for a part with 1,252 facets and depth complexity 2, to 1.86 seconds, for a part with 419,798 facets and depth complexity 9.
Dynamic Networks: Towards a Mechanical Design Visual Programming Language
Authors: Putti Shashidhar , Summers Joshua D.
Published: June 2008

The use of design exemplar in applications varying from model creation to developing feature recognition systems has been shown in the literature. Though exemplar authoring for small applications is simple, it is often seen that for complex applications, the authoring of exemplars becomes a tedious task. The use of exemplar networks (static exemplar networks) by linking smaller exemplars to form a huge exemplar has been suggested to reduce the authoring time and effort. This paper identifies the limitations of the static exemplar networks and proposes a more flexible form of networking called the “Dynamic Exemplar Network”. The use of a Dynamic node for this purpose is suggested. The structure of the dynamic node and the various types of networks that may be developed to efficiently solve a design problem is presented in the following sections.
Structural Dynamics and System Identification of Parallel Kinematic Machines
Authors: Wiens Gloria J. , Hardage David S.
Published: June 2008

One of the primary concerns associated with the machining process involves excess vibrations that can adversely affect the ability of the machine tool to accurately produce parts. This paper presents the development of a method by which the vibrational characteristics of machine tools exhibiting a parallel kinematic machine architecture may be modeled. Theoretical and experimental results are compared to demonstrate the validity of the modeling approach. The resulting model provides an effective means to guide the machine design process for the purposes of enhancing performance and improving control.
Kinematic Method for Roll Center Analysis of a Half-Car Model With Variable Wheel Tread Width
Authors: Lee Jae-Kil , Shim Jae-Kyung
Published: June 2008

A kinematic analysis method that determines roll center of a planar half-car kinematic model with variable tread width is proposed. For this, a half-car model whose wheels are assumed to be connected to the ground by revolute and prismatic joints are constructed, and instantaneous centers of the wheels with respect to the ground of the model is estimated by poles of the wheels with respect to the ground for small roll displacement. Then, the theorem of three centers is applied to determine the locus of roll center of the half-car model. Using the proposed analysis method, roll displacement of vehicle body, wheel angle variation, wheel contact point variation, and centrodes of relative motion between vehicle body and the ground, which is the locus of roll center, can be calculated.
Case Study Instrument Development for Studying Collaborative Design
Authors: Osborn Jonathan , Troy Timothy J. , Smith Gregory , Summers Joshua D.
Published: June 2008

This paper outlines a research instrument developed to analyze the relationship between communication modes, leadership styles, and team composition. The instrument is a survey that captures this information from collaborative design team members. This information can be correlated with team success, and the productive characteristics can be encouraged in future groups. The survey was distributed and analyzed in small numbers, and first round recommendations and student feedback are gathered. The developed instrument gathers background information on the student, group, and project. The project itself was defined in four stages: Problem Definition, Concept Generation, Concept Selection, and Concept Expansion. The students were asked questions about the team leadership style based on the Vroom-Yetton Model. The students were then asked how often they used various communication modes (verbal, textual, and graphical) when communicating Peer-to-Peer, Peer-to-Group, and Group as a Whole. These questions were repeated for each of the design stages. The instrument was structured and refined in order to analyze the behavior of undergraduate design students. It is intended to provide researchers and educators a tool to evaluate and critique collaborative behavior in order to streamline the design process. However, the survey was formulated broadly enough to be used in an industrial setting with small changes in the format to accommodate more experienced designers. The analysis of the original distribution revealed that the survey should be broken down into four parts corresponding to the four design stages and administered longitudinally.
Augmenting Tools for Reverse Engineering Methods
Authors: Snider Mark , Teegavarapu Sudhakar , Hesser D. Scott , Summers Joshua D.
Published: June 2008

Reverse engineering has gained importance over the past few years due to an intense competitive market aiding in the survivability of a company. This paper examines the reverse engineering process and what, how, and why it can assist in making a better design. Two well known reverse engineering methodologies are explored, the first by Otto and Wood and the second by Ingle. Each methodology is compared and contrasted according to the protocols and tools used. Among some of the reverse engineering tools detailed and illustrated are: Black box, Fishbone, Function Structure, Bill of Material, Exploded CAD models, Morphological Matrix, Subtract and Operate Procedure (SOP), House of Quality matrix, and FMEA. Even though both methodologies have highly valued tools, some of the areas in reverse engineering need additional robust tooling. This paper presents new and expanded tooling to augment the existing methods in hopes of furthering the understanding of the product, and process. Tools like Reverse Failure Mode and Effects Analysis (RFMEA), Connectivity graphs, and inter-relation matrix increase the design efficiency, quality, and the understanding of the reverse engineering process. These tools have been employed in two industry projects and one demonstrative purpose for a Design for Manufacture Class. In both of these scenarios, industry and academic, the users found that the augmented tools were useful in capturing and revealing information not previously realized.
A Simple Method for Mobility Analysis Using Reciprocal Screws
Authors: Huang Z. , Ge Q. J.
Published: June 2008

The goal of this paper is to demonstrate that the Modified Gru¨bler-Kutzbach Criterion when combined with a simple procedure for determining the reciprocal screws offers a direct and simple method for analysing highly complex mechanisms including the over-constrained parallel manipulators. Since the scalar product of screws is not dependent on the choice of the origin, one can quickly obtain a simple expression of screws by selecting an appropriate coordinate system. In such simple expression, the coordinates of a screw would include 0 or 1, and thus greatly simplifies the procedure for determine the number of constraints in a mechanism. Seven rules have been presented to help simplify the analysis process. The advocated approach makes it possible to determine, within minutes, the mobility of a highly complex mechanism by using a pencil and a paper. Many over-constrained mechanisms, including three parallel mechanisms, are presented as examples.
Issues of Similarity in Engineering Design
Authors: Anandan Srinivasan , Teegavarapu Sudhakar , Summers Joshua D.
Published: June 2008

A useful way to generate solutions to engineering design problems is to compare the solutions of design problems similar to the one at hand and validate the solutions to satisfy the new design requirements. This process involves evaluating the similarity between the design problem at hand and the various design problems in the repository. The purpose of this paper is to investigate the meaning and the use of similarity in engineering design. Various similarity theories in literature have been explored. Previous applications of these theories are limited to the retrieval of similar computer-aided design models and process plans. This paper extends the applications of these theories to the various stages of the design process.
Preliminary Design of Amorphous Products
Authors: Beiter Kurt A. , Yang Tae G. , Ishii Kos
Published: June 2008

This paper addresses the early design and development of amorphous systems. As competitive differentiators, many companies are focusing on amorphous systems comprised of primarily non-physical components, such as software, firmware, and service or business processes. This paper contrasts the development of amorphous systems with that of traditional physical systems. Whereas many tools used in new product development do apply to amorphous systems, the process and the tools need adaptation. The key points are: 1) Modeling of the system using “solution elements” instead of parts, 2) Preliminary concept generation based on use scenarios, and 3) Early consideration of the business model in the context of a complex value chain. The paper presents our proposed 10 step guide to amorphous product development and illustrates it with a “smart refrigerator” example, as well as citing the guide’s deployment in industry.
Experimental Investigation of Input Device Suitability for CAD Operations
Authors: Bayanker Sudheer , Summers Joshua D. , Gramopadhye Anand K.
Published: June 2008

This paper presents an experimental investigation into input suitability for human-computer interaction during computer aided design operations. Specifically, three types of operations, synthesis, interrogation, and modification, are examined with respect to three different types of user interfaces, mouse, direct tablet, and indirect tablet. The study, using undergraduate student participants in an introductory engineering graphics course, demonstrates that the mouse performs the highest across the dimensions of completion time and number of errors. However, the direct tablet, using a pen like device directly on the visualization screen, shows promise.
Generation of Globoidal Cam Surfaces With Conical Roller-Followers
Authors: Tsay Der-Min , Lin Sheng-Yang
Published: June 2008

Without solving any nonlinear contact equations usually encountered in traditional approaches, a relative simple, yet useful procedure to the profile determination of a globoidal cam with a conical roller-follower turret is presented. From the machining point of view for such a spatial cam cut by a conical milling/grinding tool by following its angular roller-follower turret motion, the surface geometry of the cam can be represented as the swept surfaces of the tool paths of the used cutter with a size equal to the conical roller-follower of the cam. To determine the swept surfaces of the conical tool paths, the pitch surface generated by the locus of the tool center is first identified. Subsequently, to locate the swept surfaces for the cam surfaces, the meshing vectors and meshing angles are then defined based on the pitch surface. To verify the feasibility and accuracy of the proposed procedure, both analytical formulations and numerical results are shown and compared to those obtained by an earlier technique based on the theory of screws.
Modeling Uncertainty for Planar Meso-Scale Manipulation and Assembly
Authors: Cappelleri David J. , Fink Jonathan , Kumar Vijay
Published: June 2008

While robotic assembly at the centimeter and meter length scale is well understood and is routine in the manufacturing industry, robotic grasping and manipulation for meso-scale assembly at the millimeter and sub-millimeter length scales are much more difficult. This paper explores an possible way to manipulate and assemble planar parts using a micro-manipulator with a single probe capable of pushing parts on a planar surface with visual feedback. Specifically, we describe a study of the uncertainty associated with planar surface friction with a goal of developing a model of manipulation primitives that can be used for assembly. We describe a series of experiments and data analysis algorithms that allow us to identify the main system parameters for quasi-static operation, including the friction coefficient and the force distribution, while characterizing the uncertainty associated with these parameters. This allows us to bound the range of motions resulting from the uncertainty, which is necessary to design robust open-loop meso-scale manipulation and assembly motion plans.
A Virtual Reality-Based Night Drive Simulator for the Evaluation of a Predictive Advanced Front Lighting System
Authors: Berssenbru¨gge Jan , Bauch Jochen , Gausemeier Ju¨rgen
Published: June 2008

Modern automobiles contain more and more mechatronical components to support the task of driving. Such mechatronical components are, e.g., an anti-lock braking system (ABS) and an electronic stability program (ESP) to support driving safety, or a predictive advanced front lighting system P-AFS) to enhance the lighting capabilities of a vehicle on a winding road. P-AFS uses GPS-data to locate the vehicle’s position plus digital map data to predict the curvature of the road in front of the vehicle. Based on this, P-AFS predicts the road scenario and swivels the front headlights accordingly. That way, the headlights follow the road’s curvature and optimally illuminate the road in front of the vehicle. To design, evaluate, and optimize the control algorithms within the electronic control unit (ECU) of the P-AFS component, up to 30 design variables need to be adjusted and tuned to ensure an optimal response of the system to the current road scenario. For this task, numerous time-consuming and costly test drives at night are necessary. This paper introduces a Virtual Reality-based night drive simulator that visualizes the complex lighting characteristics of automotive headlights in high detail and in real-time on a PC-based system. The user drives a simulated vehicle over a virtual test track at night, the vehicle’s motion directly influences the lighting direction of headlights, and the effect of the vehicle dynamics on the lighting can be evaluated directly in the simulator. The system is connected to the control algorithms of a P-AFS component to control the headlights swivelling for a close-to-reality simulation of a P-AFS based lighting system during the simulated night drive. That way, good combinations of the design variables can be found, based on virtual night drives in the simulator system, and the number of real test drives can be reduced significantly. Promising combinations of the design variables then can be validated in a test vehicle during a real test drive a night.
On Trigonometric Formulations of Polynomial Equations
Authors: Lipkin Harvey
Published: June 2008

The displacement analysis of open and closed kinematic chains is based on polynomial equations whose variables are functions of relative joint displacements. The objective of this paper is to investigate new and interesting properties of the transformations between the canonical cosine-sine polynomials and the even degree tan-half angle polynomials associated with displacement kinematics. Using a homogeneous coordinate formulation, it is shown that the coefficients of the polynomials are linearly related by a projective transformation whose elements can be defined recursively. The canonical cosine-sine polynomial is then transformed to a cosine or a sine polynomial which can be rooted by usual techniques. However, all real roots are bracketed between −1 and +1 which can have numerical advantages over a corresponding tan-half angle polynomial for which the entire real axis must be searched. It is also demonstrated how polynomial solutions corresponding to circular points at infinity in the tan-half angle, which are typically introduced as extraneous roots via algebraic elimination, may be easily factored out by the transformation to the cosine-sine formulation.
An Internet Based Framework for Micro Devices Assembly
Authors: Gobinath N. , Cecil J. , Son T.
Published: June 2008

This paper outlines the design of an Internet based collaborative framework to support the rapid assembly of micro devices. With the help of an agent programming language called 3APL, a distributed approach to achieving the life cycle of the various phases in the assembly of micro devices has been implemented. A discussion of the various agent resources created for a VE oriented approach is also provided in this paper.
Mechanical Design and Modelling of a Robotic Planetary Drilling System
Authors: Liu Yinghui , Weinberg Brian , Mavroidis Constantinos
Published: June 2008

Deep space drilling is necessary for appropriate chemical and biological sampling for subsurface exploration. The Robotic Planetary Drilling System (RPDS), which is currently being developed by our team, is designed to be a compact self-propelled, steerable electromechanical drilling system that can penetrate into large depths in planetary bodies. In this paper we present the detailed innovative mechanical design of the RPDS. Its main components are: a) the drill bit/cuttings bucket, b) the rotary propulsion unit including novel three 3-degree of freedom (DOF) propulsion actuators, c) the power/control module, d) the non-rotating steering unit including three 1-DOF steering actuators and e) the communication module. Three 3-DOF propulsion actuators uniformly distributed around the rotary propulsion unit impart rotating, linear motion to the drilling bit, while another three 1-DOF steering actuators provide the steering force for automatic directional control. The RPDS is propelled in the manner of a turning screw, which offers simpler kinematics structure, higher efficiency and thus, potential for miniaturization and deep drilling. The mathematical modeling and analysis of the RPDS that were conducted to evaluate its performance are also being presented in this paper.
Design and Modeling of a Peptide Based NanoTweezer
Authors: Sharma Gaurav , Rege Kaushal , Mavroidis Constantinos , Yarmush Martin L.
Published: June 2008

The design hypothesis, architectures, and preliminary computational results of a peptide based nanoTweezer are presented in this paper. We engineered the α-helical coiled coil portion of the yeast transcriptional activator peptide called GCN4 to obtain an environmentally-responsive nanoTweezer. The dimeric coiled coil peptide consists of two identical ~4.5 nm long and ~3 nm wide polypeptide chains. The actuation mechanism depends on the modifying electrostatic charges along the peptide by varying the pH of the solution resulting in the reversible movement of helices and therefore, creating the motion of the tweezer. Preliminary molecular dynamics results indicated that pH changes led to a reversible deflection of 1–2 nm with the nanoTweezer. The force profile of the nanoTweezer motion and some potential applications are also discussed.
Reduction of Induced Vibration Using Motion-Doubling Linkage Mechanisms
Authors: Rastegar J. , Zhang J.
Published: June 2008

In recent studies, the authors presented a special class of planar and spatial linkage mechanisms in which for a continuous full rotation or continuous rocking motion of the input link, the output link undergoes two continuous rocking motions. Such linkage mechanisms were referred to as the “motion-doubling” linkage mechanisms. It was also shown that in a special case of such mechanisms, the fundamental frequency of the input motion is doubled. This class of mechanisms generally has dynamics advantage over regular mechanisms designed to achieve similar gross output motions. In the present study, it is shown that in general and for the same gross output motion, motion-doubling mechanisms require lower input torques, and that the high harmonics of the input torque have smaller amplitudes. The high harmonic components present in the input torque are the main source of vibration and control problems in the system or device that the mechanism operates and its own structure. It is therefore concluded that when vibration and motion precision is of concern, such as in high-speed and precision machinery, motion-doubling mechanisms are generally more suitable from the potential vibration excitation and control points of view and actuating torque requirements.
Analysis and Optimum Synthesis of Planar Mechanisms With Clearances and Tolerances Using Interval Analysis
Authors: Diab Nadim , Smaili Ahmad
Published: June 2008

This paper presents an interval analysis based approach for analysis and optimization of planar mechanisms including the effect of link lengths tolerances and joint clearances. Mathematical models describing the effect of the mechanical errors on the desired output parameters of the mechanism are derived, followed by the commissioning of an ant-gradient based optimization scheme to find the maximum possible deviations in them. A new optimization approach is also devised to design a four bar mechanism with “minimal” sensitivity to clearances and tolerances. An analysis case study is presented and the results are displayed in the form of fuzzy membership functions and compared with results obtained using a similar approach. An example on optimum synthesis of a four-bar mechanism with joint clearances and link tolerances for hybrid exact/approximate points trajectory is also presented. Insights based on the assessment of the results are introduced.
A Flexible-Link Model for Compliant Member Synthesis
Authors: Smaili Ahmad , Hassanieh Mazen
Published: June 2008

A new approach for the synthesis of a compliant link experiencing nonlinear deformations is herein introduced. The model is being proposed as an alternative to the pseudo-rigid-body model widely used in compliant mechanisms synthesis. The proposed approach is based on the exact elliptic integral equations that govern beam deformations. The model entails the determination of a few parameters in an optimum sense that would move the endpoint of the beam through several desired positions with minimal error. A tabu-gradient optimization algorithm is employed to search the design space for an optimum solution that minimizes the square of the error between the desired and the generated endpoint positions while satisfying a set of relevant constraints. Attributes of the model are highlighted by way of several examples. A brief outline on how the proposed model is used as the basis for compliant mechanism synthesis is presented and demonstrated by way of two examples.
Stackable 5R Chains With Multiple End-Effectors: Architecture and Optimum Synthesis
Authors: Smaili Ahmad , Chaaya Bachir
Published: June 2008

Presented in this paper is a 4-dof robomech consisting of a stack of two five-bar (5R) chains with multiple end effectors to perform two distinct yet coordinated tasks simultaneously. The over-constrained kinematics chain cannot traverse continuous trajectories but may be synthesized to move the end effectors through a set of desired locations. The article elaborates on the architecture of the proposed robomech, establishes its kinematics relations and constraints, and provides dimensional synthesis scheme based on genetic algorithm and gradient search methods. A case study featuring the robomech performing spot welding operation along two distinct trajectories is included to demonstrate the applicability of the proposed robomech.
Effect of Loading Path and Specimen Shape on Inverse Identification of Elastic Properties of Composites
Authors: Michopoulos J. G. , Furukawa T.
Published: June 2008

This paper presents a methodology for using sensor-generated data from multi-degree-of-freedom mechatronic loading systems to identify the elastic moduli of a composite laminate material system. This is done not to demonstrate the method itself but rather to study how various features of the experimental and analytical procedure can affect the identification process. The analytical formulation of the identification problem is described first given the geometry of a test specimen and a loading path. The concept of singular value decomposition (associated with pseudo inversion factorization) is introduced for the purpose of parameter identification as it applies to the elastic moduli. Also, the concepts of distinguishability and uniqueness are introduced to evaluate the quality of parameter identification. The analysis is performed on a continuum model basis in order to evaluate if the proposed technique can work for specimens of arbitrary shape. Elastic coefficients were identified using pseudo-experimental (numerically synthesized) data created by finite element analysis (FEA) and the effect of the introduced distinguishability and uniqueness on the identification was investigated through several numerical examples. The effects of the form of the chosen multidimensional loading path(s) and the shape of the specimen on various features of the inverse identification process related to the elastic moduli parameter estimation are also determined. The results of the numerical studies demonstrate the efficacy of the proposed methodology and suggests subsequent avenues for optimizing the specification of the loading path both a priori and in real-time.
A Unified Subdivision Scheme for Arcs and Circles
Authors: Wang Shanglong , Ting Kwun-Lon
Published: June 2008

This paper proposes a subdivision scheme that is capable of expressing arcs and circles in a consistent form. This curve scheme is based on the unified subdivision rules for cubic B-splines, splines-in-tension, and some trigonometric splines that are capable of generating circles. The most important feature of the scheme is to change the end point rule such that the end points are forced to locate on lines connecting the center to the start point as well as the end point. With the proposed scheme, generating arcs and circles also becomes much more intuitive.
An Inverse Analysis Method for Design Optimization With Both Statistical and Fuzzy Uncertainties
Authors: Du Liu , Choi Kyung K.
Published: June 2008

Structural analysis and design optimization have recently been extended to consider various uncertainties. If the statistical data for the uncertainties are sufficient to construct the input distribution function, the uncertainties can be treated as random variables and RBDO is used; otherwise, the uncertainties can be treated as fuzzy variables and PBDO is used. However, many structural design problems include both uncertainties with sufficient data and uncertainties with insufficient data. For these problems, RBDO will yield an unreliable design since the distribution functions of uncertainties are not believable. On the other hand, treating the random variables as fuzzy variables and invoking PBDO may yield too conservative design with a higher optimum cost. This paper proposes a new design formulation using the performance measure approach (PMA). For the inverse analysis, this paper proposes a new most probable/possible point (MPPP) search method called maximal failure search (MFS), which is an integration of the enhanced hybrid mean value method (HMV+) and maximal possibility search (MPS) method. Some mathematical and physical examples are used to demonstrate the proposed inverse analysis method and design formulation.
Alternative Methods for Reliability-Based Robust Design Optimization Including Dimension Reduction Method
Authors: Lee Ikjin , Choi Kyung K. , Du Liu
Published: June 2008

The objective of reliability-based robust design optimization (RBRDO) is to minimize the product quality loss function subject to probabilistic constraints. Since the quality loss function is usually expressed in terms of the first two statistical moments, mean and variance, many methods have been proposed to accurately and efficiently estimate the moments. Among the methods, the univariate dimension reduction method (DRM), performance moment integration (PMI), and percentile difference method (PDM) are recently proposed methods. In this paper, estimation of statistical moments and their sensitivities are carried out using DRM and compared with results obtained using PMI and PDM. In addition, PMI and DRM are also compared in terms of how accurately and efficiently they estimate the statistical moments and their sensitivities of a performance function. In this comparison, PDM is excluded since PDM could not even accurately estimate the statistical moments of the performance function. Also, robust design optimization using DRM is developed and then compared with the results of RBRDO using PMI and PDM. Several numerical examples are used for the two comparisons. The comparisons show that DRM is efficient when the number of design variables is small and PMI is efficient when the number of design variables is relatively large. For the inverse reliability analysis of reliability-based design, the enriched performance measure approach (PMA+) is used.
Dynamic Pace Controller for the Robotic Gait Trainer
Authors: Ward Jeffrey A. , Hitt Joseph , Sugar Thomas , Bharadwaj Kartik
Published: June 2008

With over 600, 000 people each year surviving a stroke, it has become the leading cause of serious long-term disability in the United States [1,2,3]. Studies have proven that through repetitive task training, neural networks can be re-mapped thus increasing the mobility of the patient [4–8]. This paper is a continuation of Kartik Bharadwaj’s and Arizona State University’s research on the Robotic Gait Trainer [9]. This work is funded in part by the National Institutes of Health (NIH), grant number - 1 R43 HD04067 01. Previously the gait cycle was fixed at two seconds. For a smooth gait the patient had to be trained to follow the frequency of the robot. Audible cues were sounded to help the patient keep rhythm with the robot. This device now has an updated control methodology based on a Matlab and Simulink platform that allows the robot to dynamically adjust to the patient’s pace of gait. Data collected from an able-bodied person walking with the new device showed that the device dynamically adjusted to any normal range of walking gait. This more flexible design will allow the patient to focus more on the therapy and walk at his/her natural pace.
Design of Dissipative and Stable Assist Robots
Authors: Agrawal Sunil K. , Ryu Ji-Chul
Published: June 2008

This paper presents a methodology for design of dissipative assist robots with proven stability during set-point control. A dissipative assist robot is defined as one where the actuators continuously dissipate energy from the robot until the robot reaches the desired set-point. It is shown in this paper that a general assist robot under well known control laws is not dissipative. However, by appropriately designing the robot through inertia redistribution, the dynamic equations can be modified so that the control laws can now be proven to be both dissipative and stable under set-point control. The proposed method is demonstrated through simulation of a 3-link planar manipulator used as an assist robot to modify human functional movements in a vertical plane.
On Data-Driven Modeling and Simulation of Aero-Thermo-Mechanically Degrading Nonlinear Continuum Systems
Authors: Michopoulos J. G. , Farhat C. , Bou-Mosleh C.
Published: June 2008

Recent advances on data-driven application systems, sensor and computational technologies as well as long-term needs for efficient and accurate systemic behavior prediction monitoring in the context of realistic system design and maintenance, have brought degrading continuum systems modeling and simulation in the forefront of our activities. This paper outlines the initial steps of a methodology for applying a data-driven inverse-problem approach on the area of modeling mass-conserving degrading thermo-mechanical multi-domain nonlinear continuum structural and material systems. The methodology is applied for composite materials under simultaneous mechanical and thermal multi-field excitation and is based on mechatronic and computational automation. Furthermore, the multi-domain multiphysics modeling necessary for addressing the fluid-structure interaction involved in such systems is also discussed in the context of jet platforms with aerodynamically induced heating. Finally, simulation demonstrations are presented for the F-16 fighter jet and for a sensor-driven data solution reconstruction of an aircraft wing to demonstrate the potential for developing a material and structural health monitoring system based on he concept of dissipated energy density as a material health metric.
Computational Parameterization Simplicity and Filtering of Data-Driven Inverse Analysis for Heat Deposition Processes
Authors: Lambrakos S. G. , Michopoulos J. G.
Published: June 2008

This paper underscores two important computational aspects associated with algorithms for data-driven inverse analysis and characterization of heat deposition processes. The first involves the fact that the mathematical foundation of these algorithms suggests that a very large class of temperature fields, associated with different types of heat deposition processes and different domain geometries can be represented parametrically by a relatively small set of functions. They include linear combinations of solutions to the heat conduction equation. Issues concerning the use of algorithms based on different types of parametric representations related to different types of heat deposition processes are discussed. A prototype analysis is presented to demonstrate many characteristics of these algorithms that are significant for their practical application. The second aspect relates to the filtering property of inversion itself due to the nature of the kernel function involved with the description of the heat source. Both of these aspects are crucially beneficial to developing methodologies that effect the real-time dynamic data-driven production parameter adjustments of manufacturing processes involving heat deposition.
The Increase of the Dynamic and Static Stiffness of a Grinding Machine
Authors: Simnofske Marc , Hesselbach Ju¨rgen
Published: June 2008

The dynamic stiffness of a grinding machine influences the process stability enormously. Among other things the stability of the grinding process is affected by influences like the specification of the grinding wheel, the condition of the workpiece and machine parameters. Unfavorable combinations of these lead to chatter vibrations of the machine and chatter marks on the workpiece. This paper presents the results of experimental and theoretical investigations of the vibration behavior of a grinding machine and the design of active modules. These modules will be implemented in the structure of the machine to minimize the vibrations and additionally increase its static stiffness of the machine.
Energy-Free Adjustment of Gravity Equilibrators With Application in a Mobile Arm Support
Authors: van Dorsser Wouter D. , Barents Rogier , Wisse Boudewijn M. , Herder Just L.
Published: June 2008

Static balancing is a useful concept to reduce operating effort of mechanisms. Very often, spring mechanisms are used to achieve a constant total potential energy, thus eliminating any preferred position. The springs and the mechanism dimensions are designed to exactly or approximately balance other forces present in the mechanism, such as gravity. Quasistatically, the mechanism, once statically balanced, can be moved virtually without operating energy. In some cases it is desirable to adjust the balancer characteristic, for instance due to a change of payload in a gravity balanced mechanism. The adjustment of present static balancers requires significant operating energy. This paper will present a novel principle to adjust spring and linkage-based static balancers with no need for external energy. This principle will be explained and several variants will be shown. A mobile arm support for people with neuromuscular diseases is used as a design example. These people have very limited force and rely on their arm support to move their arms. When picking up objects their support mechanism should ideally be adjusted. Due to the limited available muscle force, this application greatly benefits from an energy-free adjustment.
Dynamic Model Verification Process for a Rotating, Elastic In-Space Tether
Authors: Mankala Kalyan K. , Agrawal Sunil K. , Canfield Stephen L. , Peddieson John
Published: June 2008

MXER-type tether systems are envisioned to transfer payloads from low-energy orbits to higher-energy orbits using propellant-free thrust. This paper deals with the process of dynamic model verification of these MXER-type tether system. The dynamics is solved using two different formulations. Four different test cases are considered for comparision. These different cases attempt to isolate and observe some component of tether dynamic response.
Optimization of Chemical Vapor Deposition Process
Authors: George Pradeep , Gea Hae Chang , Jaluria Yogesh
Published: June 2008

Chemical Vapor Deposition (CVD) process is simulated and optimized for the deposition of a thin film of silicon from silane. The key focus is on the rate of deposition and on the quality of the thin film produced. The intended application dictates the level of quality need for the film. Proper control of the governing transport processes results in large area film thickness and composition uniformity. A vertical impinging CVD reactor is considered. The goal is to optimize the CVD system. The effect of important design parameters and operating conditions are studied using numerical simulations. Then Compromise Response Surface Method (CRSM) is used to model the process over a range of susceptor temperature and inlet velocity of the reaction gases. The resulting response surface is used to optimize the CVD system.
Topology Optimization Considering Gravitational and Centrifugal Forces
Authors: Zheng Bin , Gea Hae Chang
Published: June 2008

In this paper, topology optimization problems with two types of body force are considered: gravitational force and centrifugal force. For structural design under both external and gravitational forces, a total mean compliance formulation is used to produce the stiffest structure. For rotational structural design with high angular velocity, one additional design criteria, kinetic energy, is included in the formulation. Sensitivity analyses of the total mean compliance and kinetic energy are derived. Finally, design examples are presented and compared to show the effects of body forces on the optimized results.
Mechanics of the Whole Skin Locomotion Mechanism Concentric Solid Tube Model: The Effects of Geometry and Friction on the Efficiency and Force Transmission Characteristics
Authors: Ingram Mark , Hong Dennis
Published: June 2008

In this paper, the effects of cross-sectional geometry and friction on the mechanical advantage and efficiency of the whole skin locomotion (WSL) mechanism concentric solid tube (CST) model are presented. WSL is a novel locomotion mechanism for mobile robots, which is inspired by the motility mechanisms of single celled organisms that use cytoplasmic streaming to generate pseudopods for locomotion. It works by way of an elongated toroid which turns itself inside out in a single continuous motion, effectively generating the overall motion of the cytoplasmic streaming ectoplasmic tube in amoebae. WSL can be considered as a new class of mechanism that converts the expanding and contracting motion of rings to an everting motion of the body. A brief description of the WSL mechanism is presented first, followed by the mechanics of a single and multiple actuator rings over a CST showing the relationship between the input ring tension force and the output propulsion force for a quasi-static case. Then a study of the force transmission characteristics is presented by studying the effects of cross-section geometry and friction on the efficiency and mechanical advantage of a single actuator ring over a semicircular and composite cross section CST.
Three-Dimensional Kinematic Analysis of the Actuated Spoke Wheel Robot
Authors: Laney Doug , Hong Dennis
Published: June 2008

A current problem for mobile robots in unstructured environments is their lack of general mobility. Wheeled, treaded, and legged robots each have their advantages and disadvantages, but they all lack the flexibility to be able to cope with a wide range of terrain. The actuated spoke wheel system was presented in an earlier work as an alternative locomotive method that allows unique mobility capabilities to cope with various situations. This paper presents the three-dimensional kinematic analysis of the actuated spoke wheel system with no slip and no bounce constraints at the ground contacts for a robot using a two actuated spoke wheel configuration. The first analysis will cover the case when the axle is coplanar with the line connecting the contact points, called the pivot line, and show results from two examples, corresponding to steady state turning and, in the special case, straight-line walking. The second case will describe the configuration when the pivot line is skew with the axle, comparing the robot in this configuration to an SPPS spatial mechanism. This comparison will lead to the recommendation of a more general model, based on the SPPS mechanism, that will be used to analyze the motion in both configurations.
Elastic Averaging in Flexure Mechanisms: A Muliti-Beam Parallelogram Flexure Case-Study
Authors: Awtar Shorya , Sevincer Edip
Published: June 2008

Over-constraint is an important concern in mechanism design because it can lead to a loss in desired mobility. In distributed-compliance flexure mechanisms, this problem is alleviated due to the phenomenon of elastic averaging, thus enabling performance-enhancing geometric arrangements that are otherwise unrealizable. The principle of elastic averaging is illustrated in this paper by means of a multi-beam parallelogram flexure mechanism. In a lumped-compliance configuration, this mechanism is prone to over-constraint in the presence of nominal manufacturing and assembly errors. However, with an increasing degree of distributed-compliance, the mechanism is shown to become more tolerant to such geometric imperfections. The nonlinear load-stiffening and elasto-kinematic effects in the constituent beams have an important role to play in the over-constraint and elastic averaging characteristics of this mechanism. Therefore, a parametric model that incorporates these nonlinearities is utilized in predicting the influence of a representative geometric imperfection on the primary motion stiffness of the mechanism. The proposed model utilizes a beam generalization so that varying degrees of distributed compliance are captured using a single geometric parameter.
The Analysis of Planetary Gear Trains
Authors: Raghavan Madhusudan
Published: June 2008

The Generalized Lever is a new tool in gear train representation. It extends the traditional concept of a lever representation of a planetary gear set to one that includes negative lever ratios. This allows an exhaustive permutation of the nodes of a lever, thereby leading to all possible topological arrangements of a planetary gear train. Consequently, we achieve a compact representation of large families of planetary gear trains, which would otherwise have to be dealt with on a case-by-case basis.
ELECTRIC MODULUS AND DIELECTRIC STUDIES OF ALIZARIN DOPED ANTHRAQUINONE
Authors: CHANDRA K. P. , GUPTA R. N. , PRASAD K.
Published: June 2008

The electrical properties of alizarin doped anthraquinone were investigated using a complex impedance spectroscopy technique. Dielectric study revealed a phase transition from the semiconducting to the conducting state at 53°C. The dielectric relaxation was found to be of non-Debye type. Evidence of temperature-dependent electrical relaxation phenomena as well as a positive temperature coefficient of conductivity character were observed in the sample. The frequency dependence of AC conductivity data followed a power law. Electric modulus as well as AC conductivity analyses indicated the possibility of a hopping mechanism for electrical conduction in the system. The activation energy and minimum hopping distance were estimated from the AC conductivity data.
PHASE TRANSITIONS IN SOCIAL SCIENCES: TWO-POPULATION MEAN FIELD THEORY
Authors: CONTUCCI PIERLUIGI , GALLO IGNACIO , MENCONI GIULIA
Published: June 2008

A new mean field statistical mechanics model of two interacting groups of spins is introduced, and the phase transition is studied in terms of their relative size. A jump of the average magnetization is found for large values of the mutual interaction when the relative percentage of the two populations crosses a critical threshold. It is shown how the critical percentage depends on internal interactions and on the initial magnetizations. The model is interpreted as a prototype of resident-immigrant cultural interaction, and conclusions from the social sciences perspectives are drawn.