bluuebunny/crossref_metadata_2025 huggingface dataset:
Updating Predictive Models: Calibration, Bias Correction and Identifiability
Authors: Arendt Paul D. , Chen Wei , Apley Daniel W.
Published: March 2011

Model updating, which utilizes mathematical means to combine model simulations with physical observations for improving model predictions, has been viewed as an integral part of a model validation process. While calibration is often used to “tune” uncertain model parameters, bias-correction has been used to capture model inadequacy due to a lack of knowledge of the physics of a problem. While both sources of uncertainty co-exist, these two techniques are often implemented separately in model updating. This paper examines existing approaches to model updating and presents a modular Bayesian approach as a comprehensive framework that accounts for many sources of uncertainty in a typical model updating process and provides stochastic predictions for the purpose of design. In addition to the uncertainty in the computer model parameters and the computer model itself, this framework accounts for the experimental uncertainty and the uncertainty due to the lack of data in both computer simulations and physical experiments using the Gaussian process model. Several challenges are apparent in the implementation of the modular Bayesian approach. We argue that distinguishing between uncertain model parameters (calibration) and systematic inadequacies (bias correction) is often quite challenging due to an identifiability issue. We present several explanations and examples of this issue and bring up the needs of future research in distinguishing between the two sources of uncertainty.
Design and Analysis of a Variable Stiffness Mechanism
Authors: Anubi Olugbenga M. , Crane Carl D. , Ridgeway Shanon
Published: March 2011

The design and analysis of a mechanism with variable stiffness is examined. The mechanism, which is a simple arrangement of two springs, a lever arm and a pivot bar, has an effective stiffness that is a rational function of the horizontal position d of the pivot. The external pure force acting on the system is constrained to always remain vertical. The effective stiffness is varied by changing d while keeping the point of application of the external load constant. The expression for the effective stiffness is derived. A reverse analysis is also carried out on the mechanism. Special design cases are considered. The dynamic equation of the system is derived and used to deduce the natural frequency of the mechanism from which some insights were gained on the dynamic behavior of the mechanism.
Conceptual Design of a Formula Hybrid Powertrain System Utilizing Functionality-Based Modeling Tools
Authors: Hutcheson Ryan S. , McAdams Daniel A.
Published: March 2011

Formula Hybrid is a collegiate design competition sponsored by the Society of Automotive Engineers. The competition is a spin-off of the Formula SAE series and requires that students design, build and race an electric-internal combustion engine hybrid automobile. To assist the design process of Texas A&M’s first Formula Hybrid entry, formal functionality-based conceptual design tools were applied to explore and select potential powertrain concepts. These tools included behavioral modeling along with a functionality-based sensitivity analysis. Two levels of model fidelity were used. The first (low) fidelity level was used to screen a large number of powertrain concepts. The second (high) fidelity level was used to select from a smaller but more refined set of concepts. Ultimately, four concepts were identified as suitable to use in a Formula Hybrid car. The results of this analysis were presented to the Texas A&M Formula Hybrid team. The team eventually selected a concept similar to one of the top four concepts in the study (the electric motor, battery capacity, IC engine and powertrain configuration were nearly identical as those used to parameterize the model in the analysis). Texas A&M’s Formula Hybrid team went on to win the 2009 Formula Hybrid competition by scoring 980.9 points out of 1000 (the 2nd place team scored 757.7 points). The results of the analysis done for the Texas A&M Formula Hybrid team are presented in this work along with the suggested powertrain concepts.
A Toolchain for the Design and Simulation of Foldable Programmable Matter
Authors: Gray Steven R. , Seo Jungwon , White Paul J. , Zeichner Nathan J. , Yim Mark , Kumar Vijay
Published: March 2011

This paper presents a toolchain for the design and simulation of reconfigurable robots that can be built from a single rigid sheet of smart material with embedded actuators and sensors along regular crease patterns. We call such sheets Foldable Programmable Matter (FPM). The toolchain we have created comprises an editor for drafting or modifying FPM, including locations and angles for folds. Algorithms for generating a class of folding structures are available for use. Also included is a dynamic simulation of the fold process, which provides collision detection and visualization. Thus our Foldable Programmable Matter Editor allows us to synthesize and design FPMs and simulate them in a virtual environment before committing to manufacture. The toolchain also incorporates a method of strength analysis, which is used to determine the suitability of a folded shape for specific loadings. Examples are shown for each subsection, including a beam example spanning the toolchain.
Targeted Energy Transfer to a Rotary Nonlinear Energy Sink
Authors: Hubbard Sean A. , McFarland D. Michael , Vakakis Alexander F. , Bergman Lawrence A.
Published: March 2011

We study computationally the passive, nonlinear targeted energy transfers induced by resonant interactions between a single-degree-of-freedom nonlinear energy sink and a uniform-plate model of a flexible, swept aircraft wing. We show that the nonlinear energy sink can be designed to quickly and efficiently absorb energy from one or more wing modes in a completely passive manner. Results indicate that it is feasible to use such a device to suppress or prevent aeroelastic instabilities like limit-cycle oscillations. The design of a compact nonlinear energy sink is introduced and the parameters of the device are examined. Simulations performed using a finite-element model of the wing coupled to discrete equations governing the energy sink indicate that targeted energy transfer is achievable, resulting, for example, in a rapid and significant reduction in the second bending mode response of the wing. Finally, the finite element model is used to simulate the effects of increased nonlinear energy sink stiffness, and to show the conditions under which the nonlinear energy sink will resonantly interact with higher-frequency wing modes.
Mixed Prototyping for Products Usability Evaluation
Authors: Bruno Fabio , Cosco Francesco , Angilica Agostino , Muzzupappa Maurizio
Published: March 2011

Mixed prototyping is an industrial practice that combines virtual and real components in order to realize a prototype of a product used to evaluate and assess the design choices. Recently, mixed prototypes have been also used to assess the usability of products interface. This particular application arises several problems related to the devices and the interaction techniques that, better than others, allow a natural interaction with the mixed prototype. This paper presents a mixed reality environment for usability evaluation that deals with two specific problems of this kind of application: the occlusion between real and virtual objects and the interpretation of the user’s gestures while he/she is interacting with the elements of the product interface. In particular we propose a technique able to manage both the problems by using only commodity hardware and video processing algorithms, thus avoiding the use of expensive data-gloves and tracking devices. The proposed approach has been validated through a user study addressed to establish whether and to what extent the augmented reality devices and the techniques proposed may distort the usability assessment of the product. Moreover, the user study compares the mixed reality environment adopted in this study with a classical virtual reality set-up.
E-Waste Stream Analysis and Design Implications
Authors: Behdad Sara , Kwak Minjung , Zhao Yuan , Kim Harrison , Thurston Deborah
Published: March 2011

The problem addressed in this paper is that the incoming stream of “feedstock” from product take-back systems is known to be widely variable, but the type and extent of that variability have not been well defined. This paper presents an analysis of data from an incoming e-waste stream for a computer refurbisher, and analyzes the type and degree of variability. The implications for design for sustainability are presented, along with a discussion of suggested future research needs.
Product Design Using Interface-Based Module Description
Authors: Godthi Vamsy , Yoo John Jung-Woon , Bryant Arnold Cari , Simpson Timothy W. , Kumara Soundar
Published: March 2011

To address emerging issues due to global product development and shortening product development cycles, we propose a modular product design methodology using interface-based module descriptions published through cyber-infrastructure. In this paper, we describe (1) a general way of defining interfaces, partially utilizing a standardized language of product functionality known as the Functional Basis, (2) a formal way of representing components in eXtensible Markup Language that defines a new Module Description Language (MDL), and (3) the application of the proposed methodology to the design of a product family of electronic screwdrivers, a mechanical product, extending previous work with electrical products.
Linear and Nonlinear Smooth Orthogonal Decomposition to Reconstruct Local Fatigue Dynamics: A Comparison
Authors: Segala David B. , Chelidze David , Gates Deanna , Dingwell Jonathan
Published: March 2011

Identifying physiological fatigue is important for the development of more robust training protocols, better energy supplements, and/or reduction of muscle injuries. Current fatigue measurement technologies are usually invasive and/or impractical, and may not be realizable in out of laboratory settings. A fatigue identification methodology that only uses motion kinematics measurements has a great potential for field applications. Phase space warping (PSW) features of motion kinematic time series analyzed through smooth orthogonal decomposition (SOD) have tracked individual muscle fatigue. In this paper, the performance of a standard SOD analysis is compared to its nonlinear extension using a new experimental data set. Ten healthy right-handed subjects (27 ± 2.8 years; 1.71 ± 0.10 m height; and 69.91 ± 18.26 kg body mass) perform a sawing motion by pushing a weighted handle back and forth until voluntary exhaustion. Three sets of joint kinematic angles are measured from the elbow, wrist and shoulder as well as surface Electromyography (EMG) from ten different muscle groups. A vector-valued feature time series is generated using PSW metrics estimated from movement kinematics. Dominant SOD coordinates of these features are extracted to track the individual muscle fatigue trends as indicated by mean and median frequencies of the corresponding EMG power spectra. Cross subject variability shows that considerably fewer nonlinear SOD coordinates are needed to track EMG-based fatigue markers, and that nonlinear SOD methodology captures fatigue dynamics in a lower-dimensional subspace than its linear counterpart.
Topology Optimization of Piezoelectric Energy Harvesting Devices Subjected to Stochastic Excitation
Authors: Lin Zheqi , Gea Hae Chang , Liu Shutian
Published: March 2011

Converting ambient vibration energy into electrical energy using piezoelectric energy harvester has attracted much interest in the past decades. In this paper, topology optimization is applied to design the optimal layout of the piezoelectric energy harvesting devices. The objective function is defined as to maximize the energy harvesting performance over a range of ambient vibration frequencies. Pseudo excitation method (PEM) is applied to analyze structural stationary random responses. Sensitivity analysis is derived by the adjoint method. Numerical examples are presented to demonstrate the validity of the proposed approach.
Fuzzy Control of Vertical Jumping With a Planar Biped
Authors: Hester Matthew , Wensing Patrick M. , Schmiedeler James P. , Orin David E.
Published: March 2011

This paper develops a control strategy to produce vertical jumps in a planar biped robot as a preliminary investigation into dynamic maneuvers. The control strategy was broken into two functional levels to separately solve the problems of coordination and execution of the jump maneuver. A high-level fuzzy controller addresses the complexities that arise from the system’s hybrid nonlinear dynamics and series-elastic actuators embedded in the articulated legs. A novel fuzzy training scheme is used because the system is too complex for traditional training methods. A low-level controller is based on a state machine that sequences the legs through the phases of a jump. The modular nature of the control strategy allows quick adaptation to other dynamic maneuvers. Validity is demonstrated through dynamic simulation and testing with the experimental biped KURMET which result in stable successive jumps over a range of heights.
Damage Sensing by Inverse Estimation of Electrical Resistivity of Composite Structure
Authors: Zhang Sung-Uk , Kumar Ashok V.
Published: March 2011

Damage or defect in a composite structure can significantly alter the average resistivity of the structure. A method to estimate the resistivity of composite structures using an inverse problem solving algorithm is presented that uses voltage distribution on the structure as data. Electrodes attached to the surface of the structure are used to obtain voltage data in response to current injection through a pair of these electrodes. The forward problem involves using the finite element method to predict the voltages at the electrodes using known values of resistivity. The inverse problem involves solving for the resistivity values using the experimentally measured voltage data. If the material does not have uniform properties, the computed resistivity values are average values. To explore the possibility of using this approach to detect defects in manufacturing or damage due to loading, the effect of artificially induced damage/defect on the overall resistivity of the structure is studied.
Semi-Active Vibration Control of a Marine Structure With Magnetorheological (MR) Dampers Utilizing LQR Method
Authors: Daneshfard Mohammad Sajjad , Zabihollah A.
Published: March 2011

The developing of technology has discovered new materials which have been applied to improve the performance of structures. The researchers have recently increased the attention in controllable fluids and its applications. Magnetorheological (MR) dampers are devices that employ rheological fluids to modify their mechanical properties. Their mechanical simplicity, high dynamic range, lower power requirements, large force capacity, robustness and safe manner operation in case of fail have made them attractive devices to passive, semi-active and active control in mechatronic, civil, aerospace and automotive applications. The characteristics of the MR damper change when the rheological fluid is exposed to a magnetic field changing its stiffness and damping coefficients. For this study, a marine structure exposed to different excitations has been considered in which some members have been substituted by the MR dampers. Prevention of serious damage of marine structures like the problems are generated by vibrations might be achieved by monitoring the loading conditions and by inspecting the structural integrity. The concept of smart structures can be applied to marine applications. There are plenty of marine structures in huge dimensions, for example, the overall length of a very large crude carrier exceeds 50 m. This offshore structure has 12 links and 21 nodes in each sides and each node has 2 degrees of freedom in X, Y directions. It is applied 7 MR dampers on critical links and controls the environmental vibrations and loading. Environmental loadings are divided into three general groups; Winds, wave and currents. All of maintained points are considered in analyzing of the offshore structure. Control the vibration of a marine structure in order to prevent the collapse of these structures is final purpose of this research. The controlling and the suppressing of this vibration have been done through Magnetorheological (MR) fluid dampers. The controlling method is used by the linear quadratic Regulator (LQR) as controller of this system and the results shows that it acceptable method in order to the amplitude of these vibrations.
Optimal Synthesis of a Planar Reactionless Three-Degree-of-Freedom Parallel Mechanism
Authors: Collard Jean-Francois , Gosselin Cle´ment
Published: March 2011

A reactionless mechanism is one in which no reaction forces nor moments are transmitted to the base for any arbitrary motion. This interesting property often requires to increase the total mass and the moments of inertia, leading to reduced dynamical performances. Therefore, this paper presents an optimization approach to synthesize and improve the dynamical performance of a reactionless three-degree-of-freedom planar mechanism. The three legs of this original mechanism are composed of reactionless four-bar mechanisms dynamically balanced with only one counter-rotation at the base. The optimization variables are the geometric and inertial parameters, while the goal is to minimize the global moment of inertia of each leg. This will reduce the power consumption of the three actuators and increase the agility. To meet physical and realistic requirements, the optimization problem is also constrained with bounds on the parameters, with the reachability of a given workspace and with a given range on a kinematic sensitivity index. Since different initial guesses of the optimization lead to similar objective results, it is proposed to search for several local solutions (morphologies) in the design space. The final choice among these solutions is made using additional design criteria based on the sensitivity in terms of dynamic balancing and power consumption with respect to the design parameters.
A Framework for Building Behavioral Models for Design-Stage Failure Identification Using Dimensional Analysis
Authors: Coatane´a Eric , Ritola Tuomas , Tumer Irem Y. , Jensen David
Published: March 2011

In this paper, a design-stage failure identification framework is proposed using a modeling and simulation approach based on Dimensional Analysis and qualitative physics. The proposed framework is intended to provide a new approach to model the behavior in the Functional-Failure Identification and Propagation (FFIP) framework, which estimates potential faults and their propagation paths under critical event scenarios. The initial FFIP framework is based on combining hierarchical system models of functionality and configuration, with behavioral simulation and qualitative reasoning. This paper proposes to develop a behavioral model derived from information available at the configuration level. Specifically, the new behavioral model uses design variables, which are associated with units and quantities (i.e., Mass, Length, Time, etc…). The proposed framework continues the work to allow the analysis of functional failures and fault propagation at a highly abstract system concept level before any potentially high-cost design commitments are made. The main contribution in this paper consists of developing component behavioral models based on the combination of fundamental design variables used to describe components and their units or quantities, more precisely describing components’ behavior.
The Main Elements Brought by MOKA (KBE Method) to Promote an Accelerated Technology Transfer Process Between Aerospace and Automotive Industries
Authors: Malkoun Jimmy , Gardoni Mickae¨l , Rivest Louis
Published: March 2011

Successful technology transfer process is a continuous, interactive process where individuals exchange knowledge simultaneously and continuously [1]. This article concerns the evaluation of Knowledge Management methods to support the technology transfer process. The article focuses on an analysis to be performed in order to choose the best combination of methods to meet technology transfer process needs. This paper will present the elements brought by MOKA (KM method) in order to promote technology transfer, so to solve engineering problems, develop new capabilities and improve work practice using innovative solutions. Indeed, the article will present the different stages of technology transfer process, and how the MOKA methodology responds to the various technology transfer stages criteria.
A Hybrid Reliability Approach for Reliability-Based Design Optimization
Authors: Lin Po Ting , Jaluria Yogesh , Gea Hae Chang
Published: March 2011

Reliability-based Design Optimization problems have been solved by two well-known methods: Reliability Index Approach (RIA) and Performance Measure Approach (PMA). RIA generates first-order approximate probabilistic constraints using the measures of reliability indices. For infeasible design points, the traditional RIA method suffers from inaccurate evaluation of the reliability index. To overcome this problem, the Modified Reliability Index Approach (MRIA) has been proposed. The MRIA provides the accurate solution of the reliability index but also inherits some inefficiency characteristics from the Most Probable Failure Point (MPFP) search when nonlinear constraints are involved. In this paper, the benchmark examples have been utilized to examine the efficiency and stability of both PMA and MRIA. In our study, we found that the MRIA is capable of obtaining the correct optimal solutions regardless of the locations of design points but the PMA is much efficient in the inverse reliability analysis. To take advantages of the strengths of both methods, a Hybrid Reliability Approach (HRA) is proposed. The HRA uses a selection factor that can determine which method to use during optimization iterations. Numerical examples from the proposed method are presented and compared with the MRIA and the PMA.
A Visual, Interactive Approach to Synthesis of Spherical 6R Closed Chains for Rational Motions via Constraint Manifold Modification
Authors: Purwar Anurag , Wu Jun , Gupta Aditya , Ge Q. Jeffrey
Published: March 2011

In this paper, we present an interactive, visual design approach for the dimensional synthesis of spherical 6R closed chains for a given rational motion using constraint manifold modification. This work is an extension of our previous work on the dimensional synthesis of planar 6R closed chains using the aforementioned approach. The theoretical underpinning of this work is based on representation of spherical displacements by quaternions and the kinematic mapping approach. In this way, motion of the coupler of a spherical 6R chain motion maps to a rational curve and the kinematic constraints of a spherical 6R closed chain map to hyper-dimensional algebraic surfaces in the image space of spherical displacements. Thus, the problem of determining dimensional parameters of the chain is reduced to finding the surface parameters that satisfy the geometry of the curve. This, in turn, resolves into satisfying the kinematic constraints of the chain. We provide designers an interactive, user friendly graphical tool that allows them to visually contain the image curve by simple geometric manipulation of the size, orientation, and the location of the constraint surfaces. This simple and straightforward design process lends designers an understanding of the mechanism design methodology.
On the Kinematics of Solar Mirrors Using Massively Parallel Binary Actuation
Authors: Lee Seung J. , Bilton Amy M. , Dubowsky Steven
Published: March 2011

Precision mirrors are required for effective solar energy collectors. Manufacturing such mirrors and making them robust to disturbances such as thermal gradients is expensive. In this paper, the use of parallel binary actuation to control the shape of mirrors for solar concentrators is explored. The approach embeds binary actuators in a compliant mirror substructure. Actuators are deployed in a specified pattern to correct the mirror shape. The analysis for binary-actuated compliant mirror structures is presented. Analytical models are developed for one-dimensional and two-dimensional compliant structures with embedded binary actuators. These analytical models are validated using finite element analysis and experimental studies. The models and experiments demonstrate the capabilities of binary actuated mirrors. System workspace is explored, the principle of superposition required for their control is demonstrated, as is the mirror ability to correct its figure.
Developing a Kinematic Estimation Model for a Climbing Mobile Robotic Welding System
Authors: O’Toole Aaron T. , Canfield Stephen L.
Published: March 2011

Skid steer tracked-based robots are popular due to their mechanical simplicity, zero-turning radius and greater traction. This architecture also has several advantages when employed by mobile platforms designed to climb and navigate ferrous surfaces, such as increased magnet density and low profile (center of gravity). However, creating a kinematic model for localization and motion control of this architecture is complicated due to the fact that tracks necessarily slip and do not roll. Such a model could be based on a heuristic representation, an experimentally-based characterization or a probabilistic form. This paper will extend an experimentally-based kinematic equivalence model to a climbing, track-based robot platform. The model will be adapted to account for the unique mobility characteristics associated with climbing. The accuracy of the model will be evaluated in several representative tasks. Application of this model to a climbing mobile robotic welding system (MRWS) is presented.
Combined Plant and Controller Design Using Decomposition-Based Design Optimization and the Minimum Principle
Authors: Allison James T. , Nazari Sam
Published: March 2011

An often cited motivation for using decomposition-based optimization methods to solve engineering system design problems is the ability to apply discipline-specific optimization techniques. For example, structural optimization methods have been employed within a more general system design optimization framework. We propose an extension of this principle to a new domain: control design. The simultaneous design of a physical system and its controller is addressed here using a decomposition-based approach. An optimization subproblem is defined for both the physical system (i.e., plant) design and the control system design. The plant subproblem is solved using a general optimization algorithm, while the controls subproblem is solved using a new approach based on optimal control theory. The optimal control solution, which is derived using the the Minimum Principle of Pontryagin (PMP), accounts for coupling between plant and controller design by managing additional variables and penalty terms required for system coordination. Augmented Lagrangian Coordination is used to solve the system design problem, and is demonstrated using a circuit design problem.
A Systematic Methodology for Accurate Design-Stage Estimation of Energy Consumption for Injection Molded Parts
Authors: Weissman Alexander , Ananthanarayanan Arvind , Gupta Satyandra K. , Sriram Ram D.
Published: March 2011

Today’s ubiquitous use of plastics in product design and manufacturing presents significant environmental and human health challenges. Injection molding, one of the most commonly used processes for making plastic products, consumes a significant amount of energy. A methodology for accurately estimating the energy consumed to injection-mold a part would enable environmentally conscious decision making during the product design. Unfortunately, only limited information is available at the design stage. Therefore, accurately estimating energy consumption before the part has gone into production can be challenging. In this paper, we describe a methodology for energy estimation that works with the limited amount of data available during the design stage, namely the CAD model of the part, the material name, and the production requirements. The methodology uses this data to estimate the parameters of the runner system and an appropriately sized molding machine. It then uses these estimates to compute the machine setup time and the cycle time required for the injection molding operation. This is done by appropriately abstracting information available from the mold flow simulation tools and analytical models that are traditionally used during the manufacturing stage. These times are then multiplied by the power consumed by the appropriately sized machine during each stage of the molding cycle to compute the estimated energy consumption per part.
Fastener Pattern Optimization of an Eccentrically Loaded Multi-Fastener Connection
Authors: Watkins Matthew , Jakiela Mark
Published: March 2011

This paper presents the use of a genetic algorithm in conjunction with geometric nonlinear finite element analysis to optimize the fastener pattern and lug location in an eccentrically loaded multi-fastener connection. No frictional resistance to shear was included in the model, as the connection transmitted shear loads into four dowel fasteners through bearing-type contact without fastener preload. With the goal of reducing the maximum von Mises stress in the connection to improve fatigue life, the location of the lug hole and four fastener holes were optimized to achieve 55% less maximum stress than a similar optimization using the traditional instantaneous center of rotation method. Since the maximum stress concentration was located at the edge of a fastener hole where fatigue cracks could be a concern, reduction of this quantity lowers the probability of crack growth for both bearing-type and slip-resistant connections. It was also found that the location of the maximum von Mises stress concentration jumped from the fastener region to the lug as the applied force angle was decreased below 45 degrees, thus the fastener pattern could not be optimized for lower angles.
Fostering Innovation Through Experiential Learning
Authors: Siddique Zahed , Hardre´ Patricia , Bradshaw Amy , Saha Mrinal , Mistree Farrokh
Published: March 2011

Globalization has put engineering education and the profession at a challenging crossroad. The impact of rapid technological innovations on modern societies has been amplified by the globalization of the economy. The competitiveness of the U.S., which is linked to our standard of living, is dependent on our ability to produce a large number of sufficiently innovative engineers prepared to address issues related to complex systems. Hence, our focus is on the research and development of instructional activities that address the engineering competencies related to innovation. Engineering educators and practitioners have suggested that collaborative-competitive team design events promote innovation. These competitions are popular, and they attract sponsors and participants. Beyond being popular, they are believed to provide rich learning opportunities for students. The University of Oklahoma’s Formula SAE (Society of Automotive Engineers) Racing team is highly ranked in the U.S. and world. We are in the early stages of designing, implementing, and testing a four course curriculum, around the FSAE race car, that fosters meaningful learning, innovation, systems level thinking, and the attainment of career-sustaining skills as a result of authentic experiences. We plan to identify the activity features that match with the theoretical frameworks of innovation, match them to the professional competencies, translate the events from extracurricular to curricular activities, and assess their effects on student learning and development in four technical courses our curriculum. With a view to stimulating discussion, in this paper, we highlight some of the salient features of our plan and some issues that warrant further investigation.
Output Power Optimization for Electromagnetic Vibration Energy Harvesters
Authors: Soliman M. S. M. , Abdel-Rahman E. M. , El-Saadany E. F. , Mansour R. R.
Published: March 2011

In this work, we present a procedure to optimize the output power of electromagnetic vibration energy harvesters, or micropower generators (MPGs). The procedure is based on optimizing both the electrical damping coefficient and the coil configuration, wire gauge and number of turns, to maximize the power flow from the input mechanical source to the electrical load for different load values. Also, we present a closed analytical form for the maximum efficiency of the electromagnetic MPGs.
Singularity-Free RPR and SPS Chains for Actuating Single Degree of Freedom Planar and Spherical Mechanisms
Authors: Perkins David A. , Murray Andrew P.
Published: March 2011

This paper presents a method of selecting joints relative to a fixed and moving (coupler) frame that can be used to actuate a single degree of freedom planar mechanism using a revolute-prismatic-revolute (RPR) chain or a spherical mechanism via a spherical-prismatic-spherical (SPS) chain. Given a single degree of freedom mechanism, a moving reference frame attached to any link has a motion that can be described with a single parameter. A point relative to this moving frame is sought such that it either continually increases or decreases in distance from a point in the fixed frame over the entire motion. The mechanism can then be moved by placing an actuated prismatic joint between the two points. Moreover, the singularities relative to the joints in the original mechanism are not a concern and the dimensional synthesis can focus on creating the set of circuit-defect free solutions. From this analysis, a unique fixed point is determined relative to two positions and their velocities with the following characteristic. All points in the moving reference frame that are moving away from it in the first position are approaching it in the second position, and vice versa.
Mechanism Designs for Natural Orifice Surgery: A Review
Authors: Chin Wei Jian , Nelson Carl A.
Published: March 2011

Surgery, especially intra-abdominal surgery, has taken large steps away from the conventional method of open incisions during the last two decades. Intra-abdominal surgery is now successfully performed through minimally invasive approaches. This paradigm overcomes problems encountered in the conventional method, which include substantial blood loss and long recovery periods for patients. However, a newer approach to surgery involves inserting tools through natural orifices of the patient rather than creating skin incisions. Natural orifice surgery is performed through body orifices like the esophagus or anus. This approach has substantially reduced certain disadvantages of both the conventional and minimally invasive surgeries. Natural orifice surgery has been extensively researched of late, and many institutions and companies have filed patents regarding this approach. Due to the constraints on motion and manipulation, coupled with the continued need for precise control of tool position and forces, mechanical design is an important aspect of these new technologies.
Enabling Integrated Material and Product Design Under Uncertainty Through Stochastic Constitutive Relations
Authors: Greene M. Steven , Liu Yu , Chen Wei , Liu Wing Kam , Huang Hong-Zhong
Published: March 2011

This paper presents a computational framework that mathematically propagates material microstructure uncertainties to coarser system resolutions for use in multiscale design frameworks. The computational framework uses a homogenized stochastic constitutive relation that links microstructure uncertainty with stochastic material properties. The stochastic constitutive relation formulated in this work serves as the critical link between the material and product domains in integrated material and product design. Ubiquitous fine resolution uncertainty sources influencing prediction of material properties based on their structures are categorized, and stochastic cell averaging is achieved by two advanced uncertainty quantification methods: random process polynomial chaos expansion and statistical copula functions. Both methods confront the mathematical difficulty in randomizing constitutive law parameters by capturing the marked correlation among them often seen in complex materials, thus the results proffer a more accurate probabilistic estimation of constitutive material behavior. The method put forth in this research, though quite general, is applied to a plastic, high strength steel alloy for demonstration.
Additive Manufacturing Based on Multiple Calibrated Projectors and Its Mask Image Planning
Authors: Zhou Chi , Chen Yong
Published: March 2011

Additive manufacturing (AM) processes based on mask image projection such as digital micro-mirror devices (DMD) have the potential to be fast and inexpensive. More and more research and commercial systems have been developed based on such digital devices. However, a digital micro-mirror device such as a digital light processing (DLP) projector has limited accuracy and resolution. Based on the principle of pixel blending, we present a novel AM process by using multiple DMDs to significantly improve the accuracy and resolution of built components. In order to achieve the desired pixel blending result for a given layer, it is critical to plan the mask images that will be used by the multiple projectors. In addition, the mask image planning needs to compensate the calibrated light intensity in a projection image that is usually non-uniform and non-linear. We present a general optimized pixel blending method based on direct discrete search (DDS). Its mathematic model and computing method for the mask image planning are presented. Various test cases have been performed to verify its effectiveness and efficiency.
Topological Synthesis of All 2D Mechanisms Through Assur Graphs
Authors: Shai Offer
Published: March 2011

It is well known that every planar kinematical linkage can be decomposed into basic topological structures referred as Assur Groups. A new reformulation of Assur Group concept into the terminology of rigidity theory, as Assur Graphs, has yielded the development of new theorems and methods. The paper reports on an algorithm for systematic construction of Assur Graph classes, termed fundamental Assur Graphs. From each fundamental Assur Graph it is possible to derive an infinite set of different Assur Graphs. This mapping algorithm is proved to be complete and sound, i.e., all the Assur Graphs appear in the map and each graph in the map is an Assur Graph. Once we possess the mapping of all the Assur Graphs, all valid kinematical linkage topologies can be constructed through various Assur Graph compositions.
Design of an Extended-Range Electric Vehicle for the EcoCAR Challenge
Authors: Bayar Kerem , Bezaire Beth , Cooley Brad , Kruckenberg John , Schacht Eric , Midlam-Mohler Shawn , Rizzoni Giorgio
Published: March 2011

The EcoCAR Challenge team at The Ohio State University has designed a range-extending electric vehicle capable of 40 miles all-electric range via a 22 kWh lithium-ion battery pack, with range extension and limited parallel operation supplied by a 1.8 L dedicated E85 engine. This vehicle is designed to drastically reduce fuel consumption, with an estimated fuel economy of 89 miles per gallon gasoline equivalent (mpgge), while meeting Tier II Bin 5 emissions standards. This paper documents the team’s control system development effort, starting with the vehicle architecture selection and specifying the powertrain configuration, explaining a detailed control system development process, summarizing the selected control hardware architecture at vehicle and component level, describing supervisory control algorithm design and implementation for fuel economy optimization and performance improvement, and concluding with the use of MIL and HIL techniques for system development and validation.
Some Experiences on the Teaching of Kinematics and Robotics in Mexican Universities
Authors: Rico J. M. , Cervantes-Sa´nchez J. J. , Tadeo-Cha´vez A. , Pe´rez-Soto G. I.
Published: March 2011

This paper presents some experiences on the teaching of kinematics and robotics in Mexican universities. A short sociological background information together with generalities about the curricula of mechanical and mechatronics engineers is shown. After that, the contents of two courses Mechanisms and Robotics are presented in detail. Finally, three unrelated examples of learning aids design and the introduction of more advanced mathematical tools to the study of kinematics of machinery and robotics are discussed. Nevertheless, the examples show the effort to overcome some of the deficiencies of our incoming engineering students.
The Effect of Functional Modeling on Understanding Complex Biological Systems
Authors: Helms Michael , Vattam Swaroop , Goel Ashok
Published: March 2011

Biologically inspired engineering design requires understanding of complex biological systems for use as analogues in engineering designs. In this study we seek to understand how functional representations, in particular Structure-Behavior-Function (SBF) models, enable understanding complex biological systems. Results from this study indicate that SBF representations may enable more accurate inferences about biological systems for complex and abstract questions than purely textual, or textual and diagrammatic, representations. They also suggest that no one representation is best for all types of inferences.
Structural Synthesis of Serial Robotic Manipulators Subject to Specific Motion Constraints
Authors: Kuo Chin-Hsing , Dai Jian S.
Published: March 2011

An intuitive approach for the structural synthesis of serial robotic manipulator subject to specific motion constraints is presented in this paper. According to the required f-DOF αRβT motion of the end-effector, for f = 2, 3, … or 6 and α, β = 0, 1, 2 or 3, all feasible serial-type robot structures can be systematically generated via the proposed method. The approach begins at the enumeration of joint connectivity, proceeds with the assignment of joint types, and continues by the consideration of motion constraints for the robot. A couple of examples, including the synthesis of the 3-, 4- and 5-DOF serial manipulators, are furnished for illustration. It shows that this method is especially exploitable when the end-effector is required to be immovable in certain orientations or directions with respect to either local coordinate system or global coordinate system. The result is particularly beneficial for practical industrial applications.
Wafer Scale Factories Using Assembled MEMS Robots
Authors: Murthy Rakesh , Popa Dan O.
Published: March 2011

This paper presents recent research progress in the manufacturing of MEMS based robotic positioning technology. The goal is to configure a nanofactory consisting of multiple microrobots that combine high precision with high throughput along with other application-specific requirements such as strength, dexterity, and work volume. This requires design to satisfy part mobility and dexterous manipulation with high precision. The first microrobot called the Articulated Four Axes Microrobot (AFAM) is a 3D dexterous micromanipulator robot, and we describe nano indentation experiments using AFM tips mounted on the microrobot. By combining positioning data obtained using laser interferometers and SEM imaging of nano indentation data, precision metrics such as accuracy, repeatability and resolution of the AFAM robot are determined. Preliminary reliability findings are presented. The second robot type is the ARRIpede microcrawler, and we present recent progress in microrobot precision evaluation including motion resolution and repeatability. Using these two microrobots as basic positioning and manipulation units, a nanoassembly module concept for hybrid nano assembly applications is proposed. In this paper we present recent progress in fabricating, assembling and evaluating the basic microfactory modules.
Nonlinear Constraint Model for Symmetric Three-Dimensional Beams
Authors: Sen Shiladitya , Awtar Shorya
Published: March 2011

The constraint-based design of flexure mechanisms requires a qualitative and quantitative understanding of the constraint characteristics of flexure elements that serve as constraints. This paper presents the constraint characterization of a slender, uniform and symmetric cross-section, spatial beam, which is one of the most basic flexure elements used in three-dimensional flexure mechanisms. The constraint characteristics of interest, namely stiffness and error motions, are determined from the non-linear load-displacement relations of the beam. Appropriate simplifying assumptions are made in deriving these relations so that relevant non-linear effects (load-stiffening, kinematic, and elastokinematic) are captured in a compact, closed-form, and parametric manner. The resulting spatial beam constraint model is shown to be accurate, using non-linear finite element analysis, within a load and displacement range of practical interest. The utility of this model lies in the physical and analytical insight that it offers into the constraint behavior of a spatial beam flexure, its use in 3D flexure mechanism geometries, and fundamental performance tradeoffs in flexure mechanism design.
Stabilization of a Parallel-Plate Microactuator via Control Lyapunov Functions
Authors: Lajimi S. A. M. , Heppler G. R.
Published: March 2011

This work aims at developing a new nonlinear control scheme based on control Lyapunov functions combined with backstepping to stabilize parallel-plate electrostatic MEMS actuators. Parallel-plate electrostatic MEMS actuators are not linearly controllable at the origin due to a strong non-linearity which comes from electrostatic forces. In the present study, a robust method is used to derive a new controller to thoroughly remove the instability region, and minimize the possibility of hitting the fixed electrode by the moveable plate. A large number of numerical simulations are performed to verify the analytical model. The resulting parallel-plate microactuator system shows no region of instability using the proposed controller. A comparison shows the robustness of the method in comparison with other solutions, and demonstrates a significant improvement in performance.
Turning Black-Box Into White Functions
Authors: Shan Songqing , Wang G. Gary
Published: March 2011

Modeling of high dimensional expensive black-box (HEB) functions is challenging. A recently developed method, radial basis function-based high dimensional model representation (RBF-HDMR), has been found promising. This work extends RBF-HDMR to enhance its modeling capability beyond the current second order form and “uncover” black-box functions so that not only a more accurate metamodel is obtained, but also key information of the function can be gained and thus the black-box function can be turned “white.” The key information that can be gained includes 1) functional form, 2) (non)linearity with respect to each variable, 3) variable correlations. The resultant model can be used for applications such as sensitivity analysis, visualization, and optimization. The RBF-HDMR exploration is based on identifying the existence of certain variable correlations through derived theorems. The adaptive process of exploration and modeling reveals the black-box functions till all significant variable correlations are found. The black-box functional form is then represented by a structure matrix that can manifest all orders of correlated behavior of variables. The proposed approach is tested with theoretical and practical examples. The test result demonstrates the effectiveness and efficiency of the proposed approach.