bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of a Dynamic Stabilization Spine Implant
Authors: Bryndza J. , Weiser A. , Paliwal M.
Published: July 2009

Arthritis, degenerative disc disease, spinal stenosis, and other ailments lead to the deterioration of the facet joints of the spine, causing pain and immobility in patients. Dynamic stabilization and arthroplasty of the facet joints have advantages over traditional fusion methods by eliminating pain while maintaining normal mobility and function. In the present work, a novel dynamic stabilization spine implant design was developed using computational analysis, and the final design was fabricated and mechanically tested. A model of a fused L4–L5 Functional Spinal Unit (FSU) was developed using Pro/Engineer (PTC Corporation, Needham, MA). The model was imported into commercial finite element analysis software Ansys (Ansys Inc., Canonsburg, PA), and meshed with the material properties of bone, intervertebral disc, and titanium alloy. Physiological loads (600N axial load, 10 N-m moment) were applied to the model construct following the protocol developed by others. The model was subjected to flexion/extension, axial rotation, and lateral bending, and was validated with the results reported by Kim et al. The validated FSU was used as a base to design and evaluate novel spine implant designs, using finite element anlysis. A comparison of the flexion-extension curve of six designs and an intact spine was carried out. Range of motion of the new designs showed up to 4 degrees in flexion and extension, compared to less than one degree flexion/extension in a fused spine. The design that reproduced normal range of motion best was optimized, fabricated and prepared for mechanical testing. The finalized dynamic stabilization design with spring insert was implanted into a L4-L5 FSU sawbone (Pacific Research Laboratories, Vashon, WA) using Stryker Xia pedicle screws. The construct was potted using PMMA, and was subjected to flexion/extension, axial rotation, and lateral bending loads using MTS mechanical testing machine. The stiffness of the design was assessed and compared with computational analysis results.
Temperature Control at DBS Electrodes Using Heat Sinks: Experimentally Validated FEM Model of DBS Lead Architecture
Authors: Elwassif M. , Datta A. , Bikson M.
Published: July 2009

There is a growing interest in the use of Deep Brain Stimulation (DBS) for the treatment of medically refractory movement disorders and other neurological and psychiatric conditions. The extent of temperature increases around DBS electrodes during normal operation (joule heating and increased metabolic activity) or magnetic coupling (e.g., MRI) remain poorly understood, and methods to mitigate temperature increases are actively investigated. Indeed, brain function is especially sensitive to the changes in temperature including neuronal activity, metabolic functions, blood-brain barrier integrity, molecular stability, and viability. We developed technology to control tissue heating near DBS leads by modifying the thermal properties of lead materials. A micro-thermocouple was used to measure the temperature near DBS electrodes immersed in a saline bath. 3387 and 3389 Leads were energized using Medtronic DBS stimulators. The RMS of the driving voltage was monitored. Peak steady-state temperature was determined under different RMS values. A micro-positioning system was used, which allowed the generation of temperature field map. We developed and solved a finite element method (FEM) bio-heat transfer model of DBS incorporating realistic DBS lead architecture. The model was first validated using the experimental results (by matching saline thermal conductivity and electrical conductivity) and was then applied to develop methods to control temperature rises in the brain using heat-sink technology. Experimental measurements are consistent with theoretical predictions including: 1) Peak temperature increases directly with the RMS square of the applied voltage, such that different waveforms with the same RMS induce the same peak temperature rise; 2) Peak temperatures increases with contact proximity such the maximal temperature rise was observed using adjacent contacts of lead 3389; 3) Temperature decayed over ∼2 mm distance away from energized contacts. FEM results demonstrated the central role of lead materials (material properties and geometry) in controlling temperature rise by conducting heat: namely by acting as passive heat sinks. We report that the relatively high thermal conductivity of exiting DBS lead wiring affects the temperature field, indicating the importance of detailed lead architecture. We then demonstrate how modifying lead design to optimize heat conduction can effectively control temperature increases; the manifest advantages of this approach over complimentary heat-mitigation technologies is that heat-sink controls include: 1) insensitive to the mechanisms of heating (e.g., nature of magnetic coupling); 2) does not interfere with device efficacy (e.g., the electric fields induced in the tissue during stimulation are unaffected); and 3) can be practically implemented in a broad range of implanted devices (cardiac/neuro-prothethics, pumps...) without modifying device operation or implant procedure.
Biologically-Inspired Patterned and Coated Adhesives for Medical Devices
Authors: Glass P. , Chung H. , Lee C. , Tworkoski E. , Washburn N. R. , Sitti M.
Published: July 2009

The challenge of having a medical device robustly and reversibly adhere to a tissue in a minimally-invasive way during a clinical procedure is significant and has yet to be solved. Materials that could perform this adhesion would be valuable for use in a wide array of devices, including wired and wireless endoscopes for gastrointestinal interventions; cardiovascular devices such as mobile robots that transverse the heart surface or fixation devices for open heart surgery; and for adhering craniectomy devices to the skull during decompressive treatment. Fibrillar patterned adhesives inspired by the micro- and nano-scale structures on the feet of geckos have been widely studied and synthesized and have shown great potential for reversible adhesion in dry environments. Preliminary work has also been conducted to enhance the adhesion of these materials in wet conditions by coating them with polymers that include dopamine methacrylamide (DMA), a synthetic sticky polymer inspired by the material found naturally in the holdfasts of mussels. These coated materials demonstrated wet adhesion enhancement at the nano-scale, but not at the macro-scale and not when compared to unpatterned materials. In this work, we take previously-developed gecko-inspired patterned arrays of fibers with mushroom-shaped tips which have demonstrated enhanced adhesion with respect to unpatterned materials in dry conditions and coat them with these same synthetic mussel-inspired polymers to enhance adhesion in fully-submerged wet environments. DMA-containing polymers were synthesized through a multistep process and applied to an array of micro-scale polyurethane fibers by stamping. Material samples were tested in a custom-built adhesion measurement system in contact with a 6 mm glass hemisphere in both dry and wet conditions. Flat DMA-stamped samples demonstrated as much as 7 times enhancement over uncoated samples, while patterned, coated samples demonstrated as much as 23 times adhesion enhancement. The sample also maintained 65% of its adhesive ability over 100 test cycles. These materials are the first to demonstrate reversible fibrillar adhesion in wet conditions at the macro-scale with respect to both unpatterned and uncoated materials on non-flat surfaces using intermolecular forces instead of suction forces. Versatile reversible materials capable of adhering to non-flat surfaces in wet conditions should continue to be studied for their value for a wide array of medical device applications.
Mid-IR Contact Probe for Examination of Live Cell Cultures
Authors: Saunders J. , Hilliard J. , O'Connor M. , Bhargava R.
Published: July 2009

Continuous monitoring of live cell cultures and in-vitro tissues is a major challenge in the study of model systems for cancer research. Specifically, monitoring chemical changes often requires the cells to be stained with specific fluorophores (limited chemical content) or harvested from culture (precluding longitudinal study). Recently, mid-infrared spectroscopy is being increasingly applied to measure chemical content of cells and tissues. There are no reports, however, of in-vitro monitoring of cell cultures. The major reason is the high absorption of water in this spectral region and lack of instrumentation to address this need. This project seeks to apply mid-IR in a non-destructive manner to live cell cultures and tissues while maintaining rich information content. We accomplish this by the design of a contact-method probe. We have designed a fiber optic-base beam guidance geometry and coupled it to a total internal reflection sensing element. The entire sensor is coupled to a commercial spectrometer, thus allowing for rapid translation to other laboratories. It is believed it can be a cost effective solution using current technologies with adequate SNR for down-stream chemometric analysis. One of the major design challenges was to optimally guide and utilize light from the spectrometer within the constraints of leveraging as many commercially available components, processes, and methods to most quickly translate this idea into a working device. Our major task was optical modeling and subsequent fabrication of the device. The optical models show 6 percent throughput is possible using currently available parts; 1 percent is required. The design was implemented with the optical system placed wholly within a single chassis. While a single chassis design allows for miniaturization, it presents substantial alignment challenges due to the lack of degrees of freedom for movement. These challenges are the current work focus. Proof of principle studies are on-going. We anticipate that the goal of continuous cell monitoring and in-vitro cell spectroscopy will be attained upon final integration of the device with our experimental setup.
Novel Photoinitiated Nitric Oxide Releasing Compounds for More Biocompatible Coatings on Blood and Tissue Contacting Medical Devices
Authors: Burgess B. M. , Frost M. C.
Published: July 2009

Biomedical devices that contact blood and tissue universally inspire a host response that often compromises the function of the device (i.e., intravascular sensors become coated with thrombi, artificial vascular grafts become occluded with thrombus formation and neointimal hyperplasia). Nitric oxide (NO) has been shown to be a potent inhibitor of platelet adhesion and activation and has been implicated in mediating the inflammatory response and promoting wound healing. We are currently developing NO-releasing compounds based on S-nitrosothiols derived from substituted aromatic compounds that utilize light as an external on/off trigger capable of releasing precisely controlled surface fluxes of NO. The level of NO generated is dependent on the wavelength and intensity of light shown on the compounds. Data will be presented that show the synthesis and NO-release properties of three novel compounds, S-nitroso-2-methoxybenzene, S-nitroso-3-methoxybenzene and S-nitroso-2-chlorobenzene. Ultimately, these compounds will be tethered to the surface of polymer fillers that will then be blended into hydrophobic polymers and used as coatings on biomedical devices. A model system that will be used to demonstrate the utility of this approach will be a multi-element fiber optic sensors that will contain sensing elements capable of measuring blood gases and NO-releasing fibers that locally generate enough NO to inhibit clot formation on the sensor surface, thus allowing the sensor to function reliably in vivo.
Joint Computational/Experimental Aerodynamic Study of a Simplified Tractor/Trailer Geometry
Authors: Veluri Subrahmanya P. , Roy Christopher J. , Ahmed Anwar , Rifki Rifki , Worley John C. , Recktenwald Bryan
Published: July 2009

Steady-state Reynolds averaged Navier–Stokes (RANS) simulations are presented for the three-dimensional flow over a generic tractor trailer placed in the Auburn University 3×4 ft2 suction wind tunnel. The width of the truck geometry is 10 in., and the height and length of the trailer are 1.392 and 3.4 times the width, respectively. The computational model of the wind tunnel is validated by comparing the numerical results with the data from the empty wind tunnel experiments. The comparisons include the boundary layer properties at three different locations on the floor of the test section and the flow angularity at the beginning of the test section. Three grid levels are used for the simulation of the truck geometry placed in the test section of the wind tunnel. The coarse mesh consists of 3.4×106 cells, the medium mesh consists of 11.2×106 cells and the fine mesh consists of 25.8×106 cells. The turbulence models used for both the empty tunnel simulations and the truck geometry placed in the wind tunnel are the standard Wilcox 1998 k-ω model, the SST k-ω model, the standard k-ε model, and the Spalart–Allmaras model. The surface pressure distributions on the truck geometry and the overall drag are predicted from the simulations and compared with the experimental data. The computational predictions compared well with the experimental data. This study contributes a new validation data set and computations for high Reynolds number bluff-body flows. The validation data set can be used for initial assessment in evaluating RANS models, which will be used for studying the drag or drag trends predicted by the baseline truck geometries.
Ordered Structure and the Coupling Degree of Planar Mechanism Based on Single-Open Chain and Its Application
Authors: Yang Ting-Li , Liu An-Xin , Luo Yu-Feng , Kong Xianwen , Shen Hui-Ping , Hang Lu-Bin , Jin Qiong , Yao Fang-Hua
Published: July 2009

A new viewpoint on structural composition of mechanism is proposed in this paper: any mechanism can be decomposed into a group of ordered single-open-chains (SOC). Based on the ordered SOC and its constraint property, the following concepts or principles are proposed or established: (1) the criteria for determination of basic kinematic chain (BKC). (2) the coupling degree of BKC, (3) the criteria for determination of types of degree-of-freedom, (4) the formula for calculation of number of mechanism configurations, and (5) a new unified modular method for structural, kinematic and dynamic analysis of mechanism.
Actuator Gain Distributions in Serial Robotic Manipulators to Meet Specified Task Requirements
Authors: Rios Oziel , Tesar Delbert
Published: July 2009

A serial robotic manipulator arm is a complex electro-mechanical system whose performance is highly characterized by its actuators. The actuator itself is a complex nonlinear system whose performance can be represented by the speed and torque capabilities of its motor and its accuracy depends on the resolution of the encoder as well as its ability to resist deformations under load. The mechanical gain associated with the transmission is critical to the overall performance of the actuator since it amplifies the motor torque thus improving the force capability of the manipulator housing it, reduces the motor speed to a suitable output speed operating range, enables an improvement in responsiveness (acceleration) and amplifies the stiffness improving the precision under load of the overall system. In this work, a basic analytic process that can be used to manage the actuator gain parameters to obtain an improved arm design based on a set of desired/required performance specifications will be laid out. Key to this analytic process is the mapping of the actuator parameters (speed, torque, stiffness and encoder resolution) to their effective values at the system output via the mechanical gains of the actuators as well as the effective mechanical gains of the manipulator. This forward mapping of the actuator parameters allows the designer to determine how each of the parameters influences the functional capacity of the serial manipulator arm. The actuator gains are then distributed along the effective length of the manipulator to determine the distribution effects on the performance capabilities of the system. The analytic formulation is used to address the issue of configuration management of serial robotic manipulators where the goal is to assemble a system from a finite set of components that meets some required performance specifications. To this end, two examples demonstrating a solution of the configuration management problem are presented. In the first, a manipulator is configured that is intended for light-duty applications while in the second, several manipulators intended for medium and heavy-duty applications are configured. The analytic process developed in this work can reduce the effort in the initial phases of the design process and the total number of design iterations can be reduced.
Uncertainty Problems in Model-Based Control of Redundantly Actuated Parallel Manipulators
Authors: Mu¨ller Andreas
Published: July 2009

The inverse dynamics and control of redundantly actuated PKM in the presence of uncertainties is the focus of this paper. Actuation redundancy allows for a purposeful distribution of control forces, taking into account secondary tasks, such optimal force distribution, active stiffness, and backlash avoiding control. A closed form solution of the inverse dynamics problem for simply redundantly actuated PKM is given. The applicability of the augmented PD and computed torque control schemes is analyzed. It is shown that, in the presence of model uncertainties, adopting the standard control schemes leads to parasitic perturbation forces that can not be compensated by the controls. An amended version of these control scheme is proposed that does not suffer from such effects.
A Sequential Linearization Technique for Analytical Target Cascading
Authors: Chan Kuei-Yuan
Published: July 2009

Large-scale design problems are high dimensional and deeply-coupled in nature. The complexity of such large-scale systems prevents designers from solving them as a whole. Analytical target cascading (ATC) provides a systematic approach in solving decomposed large-scale systems that has solvable subsystems. By coordinating between subsystems, ATC can obtain the same optima as they were undecomposed. However, a convergent coordination requires series of ATC iterations that may hinder the efficiency of ATC. In this research, a sequential linearization technique is proposed to improve the efficiency of ATC. The proposed linearization technique is applied to each ATC iteration, therefore each iteration has all linear subsystems that can be solved with high efficiency. One further motivation of the proposed strategy is its perceived potential in handling multilevel problems with random design variables. As previously studied, the sequential linear programming (SLP) algorithm in [1] provides a good balances between efficiency, accuracy and convergence for single-level design optimization under random design variables. The proposed linearization technique can integrate with the SLP algorithm for multilevel systems. The global convergence of this approach is ensured by a filter to determine the acceptance of the optima at each iteration and the corresponding trust region. A geometric programming example and a structure design example demonstrate the efficiency of the proposed method over standard ATC solution process without loss of accuracy.
Kinematic and Dynamic Modeling of a Helicopter Rigid Main Rotor
Authors: Battezzato Alessandro , Pastorelli Stefano , Sorli Massimo
Published: July 2009

Analysis of the kinematics and dynamics of a helicopter main rotor is presented in the paper. A rigid rotor type is assumed, where feathering angle of the blade is controlled by a swashplate mechanism. Kinematic constrains and links equilibrium are studied in order to determine the mechanism movement and the forces on the servoactuators which drive the swashplate position and orientation. The modeling presented is intended to be part of a simulation platform to evaluate fly-by-wire actuation systems performances applied to helicopter main rotors control.
Kinematical Analysis of Overconstrained Mechanism Using Computational Geometric Algebra
Authors: Piipponen Samuli , Tuomela Jukka , Arponen Teijo
Published: July 2009

In this paper we will show how the methods of computational and geometric algebra can be used to analyze the kinematics of multibody systems. As an example we treat thoroughly the well known Bricard’s mechanism which is a classic example of so called overconstrained mechanism, but the same methods can be applied to wide class of rigid multibody systems. It turns out that the configuration space of Bricard’s system is a smooth closed curve which can be explicitly parametrized. Our computations also yield a new formulation of constraints which is better than the original one from the point of view of numerical simulations.
The Conceptual Design of a Perfusion Reactor Using a Complexity Measure
Authors: Bischof Andreas , Angeles Jorge , Blessing Lucienne
Published: July 2009

The conceptual design of a perfusion reactor is the subject of this paper. The main objective of the reactor is the provision of nutrients to living cells grown in a porous medium fabricated of a given ceramic foam. In order to increase reactor throughput, the nutrients should be provided in a minimum time, without affecting the cell life. Various layouts of identical ceramic-foam pieces hosting the cells are proposed, the purpose being to select the variant with the highest likelihood of optimum performance, in the absence of a detailed mathematical model. A simple model is proposed, drawn from the discipline of hydraulic dynamical systems, which leads to a flow-complexity measure. The variant with the lowest complexity is then selected, for which a possible embodiment is proposed.
Functional Characterization of Compliant Building Blocks Utilizing Eigentwists and Eigenwrenches
Authors: Kim Charles J.
Published: July 2009

Compliant mechanisms are devices which utilize the flexibility of their constituent members to transmit motion and forces. Unlike their rigid body counterparts, compliant mechanisms typically contain no traditional joints. The focus of this research is the development of a building block approach for the synthesis of compliant mechanisms. Building block methods better facilitate the augmentation of designer intuition while offering a systematic approach to open-ended problems. In this paper, we investigate the use of the eigentwists and eigenwrenches of a deformable body to characterize basic kinematic function. The eigentwists and eigenwrenches are shown to demonstrate parametric behavior when applied to the compliant dyad building block, and in special cases may be compared to compliance ellipsoids. The paper concludes by articulating future research in a building block approach to compliant mechanism synthesis.
Optimal Trajectory Planning for Redundant Manipulators Based on Minimum Jerk
Authors: Yang Jingzhou , Kim Joo , Pitarch Esteban Pena , Abdel-Malek Karim
Published: July 2009

This paper presents an optimization-based method to solve the smooth trajectory planning problem where the user knows only the start and end points of the end-effector or the via point plus the start and end target points. For the start and end target points, we use an optimization approach to determine the manipulator configurations. Having obtained the desired minimum jerk path in the Cartesian space using the minimum jerk theory and having represented each joint motion by the third-degree B-spline curve with unknown parameters (i.e., control points), an optimization approach, rather than the pseudoinverse technique for inverse kinematics, is used to calculate the control points of each joint spline curve. The objective function includes several parts: (a) dynamic effort; (b) the inconsistency function, which is the joint rate change (first derivative) and predicted overall trend from the initial point to the end point; and (c) the nonsmoothness function of the trajectory, which is the second derivative of the joint trajectory. This method can be used for robotic manipulators with any number of degrees of freedom. Minimum jerk trajectories are desirable for their similarity to human joint movements, for their amenability to limit robot vibrations, and for their control (i.e., enhancement of control performance). Illustrative examples are presented to demonstrate the method.
Creative Thinking in a First Year Mechanical Engineering Design Course at the Massachusetts Institute of Technology: A Community of Practice Model
Authors: Rush Monica , Wallace David , Newman Dava
Published: July 2009

This paper investigates student acquisition of creative thinking skills in Solving Real Problems, a first year engineering design course in the Mechanical Engineering Department at the Massachusetts Institute of Technology. This class was developed around a service-learning model where teams of two to six students worked with community-based partners to design products for use in their communities. Each team also had at least one faculty member and one teaching assistant working alongside the students as additional team members. Teaching techniques used in the class included multiple in-class idea generation exercises, individual and group assignments, concept, visualization, and fabrication instruction. There were thirteen students total enrolled in the class, two of whom were upperclassmen, one of whom was cross-registered from another university. The participants of this study are the ten first-year MIT students that took Solving Real Problems (2.00B) in spring semester 2007, consisting of five females and five males. At the end of the semester, eleven students total, including each of these ten first-year MIT students, participated in focus groups and responded affirmatively to the question “Thinking about Solving Real Problems in particular, do you think that the class improved your ability to be creative?” Thirty minute follow-up interviews with each student explored this improvement in creativity and make up the core data analyzed in this paper. Common themes discussed by students in relation to creativity include the interactive lecture and lab environment, the involvement of the professors and confidence and hands-on practice, suggesting a community of practice model of learning creativity in the classroom.
Forward Displacement Analysis of a Quadratic Planar Parallel Manipulator: 3-RPR Parallel Manipulator With Similar Triangular Platforms
Authors: Kong Xianwen , Gosselin Cle´ment M.
Published: July 2009

A quadratic parallel manipulator refers to a parallel manipulator with a quadratic characteristic polynomial. This paper revisits the forward displacement analysis (FDA) of a quadratic parallel manipulator: 3-RPR planar parallel manipulator with similar triangular platforms. Although it has been revealed numerically elsewhere that for this parallel manipulator, the four solutions to the FDA fall, respectively, into its four singularity-free regions (in its workspace), it is unclear if there exists a one-to-one correspondence between the four formulas, each producing one solution to the FDA, and the four singularity-free regions. This paper will prove that such a one-to-one correspondence exists. Therefore, a unique solution to the FDA can be obtained in a straightforward way for such a parallel manipulator if the singularity-free region in which it works is specified.
An Effective Random Field Characterization for Probability Analysis and Design
Authors: Xi Zhimin , Youn Byeng D.
Published: July 2009

So far manufacturing tolerance variability over samples has been widely considered in many engineering design problems. Traditionally the tolerance variability is modeled as a spatially independent random parameter although the variability is a function of spatial variables (x, y, and z) in many engineering applications. Little attention has been paid to spatial variability (or random field) in manufacturing and operational conditions, which may dominantly affect system performances in smaller scale applications. This paper presents an effective approach to characterize a random field for probability analysis and design. The Proper Orthogonal Decomposition (POD) method is employed to extract the important signatures of the random field over product samples. A normalized posteriori error is defined to automatically decide the minimal number of the important signatures while preserving a prescribed accuracy in approximating the random field. The random projected values of the spatial variability over the samples onto each important signature are modeled as a random parameter. The signatures and corresponding random parameters are thus used for modeling the random field. A Chi-Squae goodness-of-fit test is used for determining statistical models of random parameters. This proposed approach can facilitate to characterize the random field for probability analysis and design. By modeling the random field with the most significant random signatures, the Eigenvector Dimension Reduction (EDR) method can be employed for probability analysis because of its relatively high efficiency and accuracy. Two examples (one beam and Micro-Electro-Mechanical Systems (MEMS) bistable mechanism) are used to illustrate the effectiveness of the proposed approach while considering only a geometric random field. Compared to Monte Carlo Simulation (MCS), the proposed random field approach is appeared to be very accurate and efficient. Moreover, the results show that the random field variation cannot be neglected for probability analysis and design practices.
Modeling Variability in Torso Shape for Chair and Seat Design
Authors: Reed Matthew P. , Parkinson Matthew B.
Published: July 2009

Anthropometric data are widely used in the design of chairs, seats, and other furniture intended for seated use. These data are valuable for determining the overall height, width, and depth of a chair, but contain little information about body shape that can be used to choose appropriate contours for backrests. A new method is presented for statistical modeling of three-dimensional torso shape for use in designing chairs and seats. Laser-scan data from a large-scale civilian anthropometric survey were extracted and analyzed using principal component analysis. Multivariate regression was applied to predict the average body shape as a function of overall anthropometric variables. For optimization applications, the statistical model can be exercised to randomly sample the space of torso shapes for automated virtual fitting trials. This approach also facilitates trade-off analyses and other the application of other design decision-making methods. Although seating is the specific example here, the method is generally applicable to other designing for human variability situations in which applicable body contour data are available.
Calibration Approach for Thermomechanical In-Plane Microactuator Self-Sensing
Authors: Teichert Kendall B. , Jensen Brian D.
Published: July 2009

Microelectromecahanical system (MEMS) actuation is a growing area of research. One obstacle for use of actuation in MEMS applications is the difficulty of proper sensing. Recent work has been done that shows the potential for thermomechanical in-plane microactuators (TIMs) to act as self-sensors by using the piezoresistive characteristic of silicon. However, in order to implement this technology a calibration method needs to be devised to account for variations between TIMs. This work presents an approach for this calibration consisting of two parts that compensate for variation in fabrication and material properties. Test structures are presented that will enable this calibration to be done on-chip, and validation is given for the usability of this approach. Two validation approaches are used. For the first approach, data previously gathered was analyzed using the TIM itself for calibration. This approach showed significant correlation with the model; however, this approach confounds any sensing signal and therefore was used only for general model validation. The second approach uses a novel calibration structure that decouples the mechanical and electrical characteristics. This approach showed correlation with test data within the bounds of experimental uncertainty in nearly all cases. Suggestions are given concerning implementation.
An Approach to Automate Concept Generation of Sheet Metal Parts Based on Manufacturing Operations
Authors: Patel Jay , Campbell Matthew I.
Published: July 2009

This paper describes an approach to automate the design for sheet metal parts that are not only novel and manufacturable but also satisfies multiple objective functions such as material cost and manufacturability. Unlike commercial software tools such as Pro/SHEETMETAL which aids the user in finalizing and determining the sequence of manufacturing operations for a specified component, our approach starts with spatial constraints in order to create the component geometries and helps the designer design. While there is an enormous set of parts that can feasibly be generated with sheet metal, it is difficult to define this space systematically. To solve this problem, we currently have 88 design rules that have been developed for four basic sheet metal operations: slitting, notching, shearing, and bending. A recipe of the operations for a final optimal design is then presented to the manufacturing engineers thus saving them time and cost. The technique revealed in this paper represents candidate solutions as a graph of nodes and arcs where each node is a rectangular patch of sheet metal, and modifications are progressively made to the sheet to maintain the parts manufacturability. They are presented in the form of Standard Tessellation Language files (.stl) that can be transferred into available modeling software for further analysis. The overall purpose of this research is to provide creative designs to the designer granting him/her a new perspective and to check all the solutions for manufacturability in the early stage of design process. An example sheet metal design problem is shown in this paper with some of the preliminary designs that our approach created.
Shape Optimization of a Camoid Follower Surface
Authors: Aguib Karim A. , Hekman Keith A. , Nassef Ashraf O.
Published: July 2009

Camoids are three dimensional cams that can produce more complex follower output than plain disc cams. A camoid follower motion is described by a surface rather than a curve. The camoid profile can be directly synthesized once the follower surface is fully described. To define a camoid follower motion surface it is required that the surface pass by all predefined constraints. Constraints can be follower position, velocity and acceleration. These design constraints are scattered all along the camoid follower surface. Hence a fitting technique is needed to satisfy these constraints which include position and its derivatives (velocity and acceleration). Furthermore if the fitting function can be of a parametric nature, then it would be possible to optimize the follower surface to obtain better performance according to a specific objective. Previous research has established a method to fit camoid follower surface positions, but did not tackle the satisfaction of derivative constraints. This paper presents a method for defining a camoid follower characteristic surface B-Splines on two steps first synthesizing the sectional cam curves then using a surface interpolation technique to generate the follower characteristic surface. The fitting technique is parametric in nature which allows for its optimization. Real coded Genetic algorithms are used to optimize the parameters of the surface to meet a specified objective function. A demonstration problem to illustrate the suggested methodology is presented.
A Strategic Module-Based Platform Design Method for Developing Customized Products in Dynamic and Uncertain Market Environments
Authors: Moon Seung Ki , Simpson Timothy W. , Kumara Soundar R. T.
Published: July 2009

Product family design facilitates mass customization by allowing highly differentiated products to be developed around a platform while targeting products to distinct market segments. Therefore, effective platforming of products is a cost-effective way to achieve mass customization The objective in this research is to develop a Strategic Module-based Platform Design Method (SMPDM) to determine a platform design strategy to support product family design in a dynamic and uncertain environment. Ontologies are used to represent products and enable sharing and reuse of design information. Data mining techniques are used to identify a platform and modules by utilizing design information stored in a large database or repository. To determine a platform for family design in dynamic and uncertain market environments, the SMPDM uses agent-based decision-making, involving a market-based negotiation mechanism and a game theoretic approach based on module-based platform concepts and a mathematical model. To demonstrate and validate the usefulness of the proposed method, it is applied to a family of power tools and tested in multiple scenario-based experiments. The SMPDM provides an optimal platform design strategy that can be adapted to various dynamic and uncertain market environments. Therefore, the SMPDM can help develop design strategies to manage and create a cost-effective variety of products based on a platform in support of mass customization.
Tolerance Analysis in Machining: An Approach Combining the Model of Manufactured Part and the Jacobian-Torsor Model
Authors: Kamali Nejad Mojtaba , Desrochers Alain , Villeneuve Franc¸ois , Vignat Fre´de´ric
Published: July 2009

To perform tolerance analysis in machining, a combined approach which blends the benefits of the Model of Manufactured Part (the MMP model) and the Jacobian-Torsor model is proposed. The former is based on the CAD nominal model, where deviations are described relative to the nominal part using small displacement torsor. The later starts with the kinematic dimension chains and expresses the relative position and orientation of the various components of the chosen kinematic chain by Jacobian matrices. The Jacobian-Torsor model uses interval arithmetic for expressing the possible variation of the functional elements and for calculating the extreme bounds of the functional requirements. In the following sections, the two aforementioned models will first be outlined before the new combined approach for tolerance analysis in machining is presented. This new approach uses the advantages of the MMP model to simulate the machining operation, taking into account positioning and machining defects. Furthermore it takes advantages of the interval-based formulation which has been used in the Jacobian Torsor model. The combined approach is finally applied on an example.
An Optimization-Based Approach for Grasp Posture Generation of Digital Hand
Authors: Endo Yui , Kanai Satoshi , Miyata Natsuki , Kouchi Makiko , Mochimaru Masaaki , Konno Jun , Ogasawara Michiyo , Shimokawa Marie
Published: July 2009

Recently, as handheld information appliances, such as mobile phones, PDAs, have widely spread, the development of these appliances should pay more attention in their ergonomic design. However, the user tests for developing the “ergonomic” appliances are usually done by many real subjects testing a variety of these physical mockups, and the process of these tests usually requires the expensive cost and has to take a long time. So, we propose a software system of an automatic ergonomic assessment system for designing handheld information appliances by integrating the digital hand model with the 3D product model of the appliance. Our system has the following four feature functions for ergonomic assessment: 1) Generation of kinematically and geometrically accurate digital hand models with rich dimensional variation, 2) automatic grasp posture generation and evaluation of the posture stability by estimating the force-closure and the grasp quality, 3) automatic evaluation of ease of the finger motion in operating the user interface, 4) aiding the designers to re-design the housing shapes and user-interfaces in the product model. In this paper we propose a new optimization-based method the 2) of the above functions. As the objective function, we use the number of the contact points, the fit of the specific part of the hand surface for the feature edges of the product surface and the margin for the constraints on the joint angle limits of the figures. The experimental studies on the grasp posture generation for the digital camera indicate that more realistic grasp posture could be generated using the proposed optimization-based method than the one using our former method.
Active Vibration Control of Storage and Retrieval Machines
Authors: Go¨rges Daniel , Kroneis Jens , Liu Steven
Published: July 2009

In this paper a novel concept for active vibration control of storage and retrieval machines is presented. The storage and retrieval machine is modeled based on the Bernoulli-Euler beam theory, yielding an infinite-dimensional model, and the assumed modes method in order to obtain a finite-dimensional model. The resulting model is of low order, a fourth-order model regarding the first and the second eigenfrequency describes the dynamics sufficiently. The model is verified on an experimental storage and retrieval machine. Several active vibration control strategies are studied, including trajectory planning approaches like higher-order trajectory planning, feedforward control approaches like trajectory filtering and input shaping, and feedback control approaches like state-feedback control. The strategies are evaluated by simulation and compared via performance measures.
Using a Virtual Reality-Based Night Drive Simulator as a Tool for the Virtual Prototyping of an Advanced Leveling Light System
Authors: Berssenbru¨gge Jan , Kreft Sven , Gausemeier Ju¨rgen
Published: July 2009

Modern automobiles contain various mechatronical components to support the task of driving. To enhance driver vision and driving safety at night time, advanced lighting systems, such as a predictive advanced front lighting system (PAFS) enhance automotive lighting by swiveling the headlights horizontally into approaching curves on a winding road. In addition to this, basic leveling light systems tilt the headlights vertically, in order to adjust to the vehicle chassis pitch due to the vehicle load or suspension effects based on the vehicle dynamics from driving on a rough road. More advanced leveling systems even account for the vertical course of an undulating road using GPS-data to locate the vehicle’s position plus digital map data to predict the vertical course of the road in front of the vehicle. That way, the headlights follow the road curvature and illuminate the road ahead of the vehicle without glaring oncoming traffic. In order to design, evaluate, and optimize the control algorithm within the electronic control unit (ECU) of the leveling light system, various control parameter values need to be adjusted and fine-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 proposes to use a Virtual Reality-based night driving simulator as tool to simulate and evaluate an advanced leveling light system. The PC-based night drive simulator visualizes the complex beam patterns of automotive headlights in high detail and in real-time. The user drives a simulated vehicle over a virtual test track at night, while the vehicle motion directly affects the lighting direction of headlights. Thus, the effect of the vehicle dynamics on the lighting can be evaluated directly in the simulator. The system is connected to the control algorithm of the advanced leveling light system, which controls the headlights tilting angle. This provides a close-to-reality simulation of the advanced leveling light system during a simulated drive at night. That way, within the virtual prototyping process of the advanced leveling light system, good combinations of control parameter values can be indentified, based on virtual test drives in the night driving simulator, and the number of real test drives can be reduced significantly. Promising combinations of the control parameter values then can be validated during a real test drive a night.
Sensitivity Analysis of Relative Worth in Empirical and Simulation-Based QFD Matrices
Authors: Kalapurackal Robins M. , Takai Shun
Published: July 2009

Quality function deployment (QFD) is one of the most popular tools used in the product development process. It relates customer requirements to product requirements and enables engineers to determine which product requirement is more important than the others in satisfying customers. Some of the benefits of QFD are cost reduction, fewer design changes at the start of production, and improved communication among engineers. QFD applications use various approaches (i.e., worth calculation schemes and rating scales) to calculate the worth of requirements. The purpose of this paper is to study the change in the relative worth (normalized worth) of product requirements yielded by different rating scales and calculation schemes. We studied empirical and simulation-generated QFD matrices to determine how calculation schemes and rating scales influence the relative worth of requirements. Two representative scales and two calculation schemes are used to find the most and least sensitive cases, and the influence of the number of rows and columns in the relative worth of requirements. From the results, we identified the least sensitive and most sensitive combination of calculation scheme and rating scale. We also learned that QFD matrices become less sensitive to changes in rating scale and calculation scheme as the number of columns increases.
Path Planning for a Digital Robotic Arm
Authors: Zhang Yanrong , Cipra Raymond J.
Published: July 2009

Discretely actuated or digital robotic manipulators have become popular because they are highly repeatable, need no feedback control, and are relatively less expensive and lightweight compared to continuously actuated manipulators. This research investigates trajectory planning for discretely actuated manipulators within a static environment without obstacles and with known initial and final positions. In particular, the focus will be on minimizing oscillations of a path trajectory and minimizing the deviation from the ideal path, as well as minimizing the torque required to actuate each joint. Motion strategies are developed and their effect studied.
Displacement and Blocking Force Modeling for Piezoelectric Uniflex Microactuators
Authors: Kommepalli Hareesh K. R. , Yu Han G. , Tadigadapa Srinivas A. , Rahn Christopher D. , Trolier-McKinstry Susan , Muhlstein Christopher L.
Published: July 2009

Microactuators provide controlled motion and force for applications ranging from RF switches to rate gyros. Large amplitude response in piezoelectric actuators requires amplification of their small strain. This paper studies a uniflex microactuator that combines the strain amplification mechanisms of a unimorph and flexural motion to produce large displacement and blocking force. An analytical model is developed with three connected beams and a reflective symmetric boundary condition that predicts actuator displacement and blocking force as a function of the applied voltage. The model shows that the uniflex design requires appropriate parameter ranges, especially the clearance between the unimorph and aluminum cap, to ensure that both the unimorph and flexural amplification effects are realized. With a weakened joint at the unimorph/cap interface, the model accurately predicts the displacement and blocking force of four actuators.