bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of Planetary Drives for Maximum Reduction Ratio by Use of Non-Standard Involute Gears
Authors: Tan Jie
Published: May 2009

Planetary drives offer high torque capacity and large reduction ratio within envelope constraints. This paper attempts to maximize the reduction ratio by applying non-standard (modified) involute gears. Two issues encountered in the effort are addressed: i) The reduction ratio is limited by outer diameter interference of the planets, and ii) commonly used non-standard gear calculation methods add significant complexity to the problem because of the center distance and the gear outer diameter being complex non-linear functions of the modification coefficient. A new gear modification coefficient is first defined which relates to the mid-working depth radius, tip circle radius and center distance in simple linear functions. Using the proposed method to greatly simplify conditions of center distance compatibility and outer diameter interference, the limit on reduction ratio is then derived and expressed in explicit relation to the modification coefficients, thus pointing out directions for maximizing the reduction ratio.
An Integrated Approach to Combine Computer-Based Training (CBT) and Immersive Training (ImT) for Mechanical Assembly
Authors: Kim YoungJun , Jayaram Uma , Jayaram Sankar
Published: May 2009

There is currently a vital need to improve effectiveness and efficiency of training technologies used in industry — especially in the areas of assembly, disassembly, maintenance, installation, and troubleshooting. Current training techniques vary from paper-based (books, manuals) to computer-based (presentations, web pages, on-line help, etc.) to immersive (VR-based) systems. This paper presents an integrated approach to combine Computer-Based Training (CBT) and Immersive Training (ImT). We coin this approach iTrain, integrated Training. iTrain consists of CBT, ImT, and a learning management tool. The goal is to enable transformational change of training through the creation of a new generation training ensemble. In this paper, the methodology, approaches, and algorithms for such integrated training systems are presented. A CBT application that allows interactive training using traditional computer tools (keyboard and mouse) and an ImT application have been integrated using this methodology. These applications are integrated with the Sharable Content Object Reference Model (SCORM) so that the training can be managed, tracked, and evaluated in an effective and efficient. A unified approach has been designed to manage common data such as model name, and model ID. A database has been designed and implemented for access from CBT, ImT, and LMS. This prototype integrated training system is presented and discussed in this paper.
OAM+: An Assembly Data Model for Legacy Systems Engineering
Authors: Murshed S. M. Mahbub , Shah Jami J. , Jagasivamani Vadivel , Wasfy Ayman , Hislop David W.
Published: May 2009

This paper presents a new assembly model named open assembly model plus (OAM+) to support legacy systems engineering (LSE). LSE is a collection of technologies for prolonging the life of old mechanical systems. Rapid Re-Engineering System (RRES), a subsystem of LSE is geared towards the fast production of redesigned parts customized to the manufacturing capability available. RRES requires the extraction of initial part geometry, parameters, interfacing constraints, kinematic constraints, and technical function. These specifications need to be imprinted on the CAD model before iterative redesign. A CAD data model is needed that can carry all the functional constraints. A detailed comparison of all the available assembly model shows that none of them can provide all these requirements in one place. Assembly feature based, object oriented assembly model OAM+ is developed to meet these requirements in one model. OAM+ can be used to perform kinematic analysis, force analysis and can exchange feature data using N-Rep feature definition language between different modules of RRES. OAM+ is based on part and assembly features in N-Rep.
Hysteresis and Creep Compensation for Piezoelectric Actuators Applied to the Feedforward Control Command of Flexible Structures
Authors: Becker Jens , Kra¨mer Thomas , Gaul Lothar
Published: May 2009

Piezoelectric materials are known to exhibit nonlinear effects if they are operated outside their linear small-signal regime, which significantly degrades the performance of structural control concepts. In this contribution, these nonlinear effects are experimentally investigated in the context of a feedforward control application, where a control command is designed to steer the tip of a cantilever beam by means of a piezoelectric patch actuator from initial to a prescribed desired final stationary deflection. As expected, the encountered nonlinear effects degrade the control performance with increasing applied electrical field. Hence, a modified feedforward control design procedure is proposed. The overall nonlinear system model is recast in a series connection of an input nonlinearity and the linear dynamics of the mechanical structure, which the feedforward control to be designed in two steps: First, a feedforward control for the linear model part is derived based on an approach exploting the notion of flatness in combination with modal analysis of the linear dynamics. It uses the finite-element method to derive the linear dynamics of the piezoelectric structure. Secondly, an inverse filter is designed to compensate for the nonlinear piezoelectric hysteresis and creep effects. By insertion of this inverse filter at the system input, i.e. by filtering the feedforward control, very good tracking control performance is recovered in both small and large-signal operation of the piezoelectric actuator. This filter itself is derived by inversion of a model of the nonlinearities in the discrete-time domain. The chosen model for the hysteresis is based on polynomial approximations of the hysteresis loops, appropriate scaling of these loops to the actual point of operation by keeping track of the input signal reversals and on implementation of the physically motivated Madelung rules that the piezoelectric hysteresis obeys. The creep is found to behave according to a Kelvin-Voigt viscoelastic model. Various experiments for the piezoelectrically actuated beam show that the modified feedforward control design yields very good tracking performance also outside of the small-signal regime by application of the compensation filter. The excellent feedforward tracking control performance predicted by simulations of the full (linear) finite-element model is verified. The designed feedforward control realizes very fast rest-to-rest transition in less than half of the period of the first structural mode. As an interesting application of such a feedforward control, a two-degree-of-freedom control concept combining the presented feedforward control and additional feedback control is investigated. By use of the feedforward control, the feedback can be relatively simple because it is only responsible for disturbance rejection and adding robustness.
Adaptive Periodic Noise Cancellation for Cooling Fans With Varying Rotational Speed
Authors: Kinney Charles E. , de Callafon Raymond A.
Published: May 2009

This paper presents a novel method of simultaneously tracking and rejecting time-varying sinusoids in the presence of random noise by using feedback control. The technique applies the internal model-principle to time-varying disturbances by using an extended Kalman filter to create time-varying gains and a time-varying internal model. The state feedback gain, however, is not time-varying and is designed using standard time-invariant LQR methods. This control algorithm is applied to active noise cancelation and in simulations is shown to converge quickly in the presence of noise. Methods of improving convergence of this algorithm are discussed.
Modeling Process Platform-Based Production Reconfiguration With Petri Nets
Authors: Jiao Roger Jianxin , Zhang Linda Lianfeng
Published: May 2009

The production processes of product families involve diverse changeovers in manufacturing and assembly processes in order to accommodate a high variety of component parts and assemblies. Reconfiguring production processes based on process platforms has been recognized as a promising means for companies to produce product variety while achieving mass production efficiency. Aiming at modeling support to production reconfiguration, this paper develops a multilevel system of nested colored object-oriented Petri nets (PNs) with changeable structures. In accordance with the fundamental issues of production reconfiguration, the modeling formalism is developed by taking advantages of several PNs techniques, including colored PNs, object-oriented PNs, changeable PNs, and nested PNs. The modeling formalism comprises a resource net, manufacturing net, assembly net and process net. The paper demonstrates how these net definitions are applied to specify production processes at different levels of abstraction. Also reported is a case study in an electronics company. The application results reveals the feasibility of the nested colored object-oriented PNs with changeable structures for capturing and representing the logic of production reconfiguration based on process platforms.
Process Platform Formation for Product Families
Authors: Jiao Roger Jianxin , Zhang Linda Lianfeng
Published: May 2009

In accordance with the product families, process platforms have been recognized as a promising tool for companies to configure optimal, yet similar, production processes for producing different products. This paper tackles process platform formation from large volumes of production data available in companies’ production systems. A data mining methodology based on text mining and tree matching is developed for the formation of process platforms. A case study of high variety production of vibration motors for mobile phones is reported to prove the feasibility and potential of forming process platforms using text mining and tree matching.
Finite-Time Controllability of Fractional-Order Systems
Authors: Adams Jay L. , Hartley Tom T.
Published: May 2009

In this paper the conditions that lead to a system output remaining at zero with zero input are considered. It is shown that the initialization of fractional-order integrators plays a key role in determining whether the integrator output will remain at a zero with zero input. Three examples are given that demonstrate the importance of initialization for integrators of order less than unity, inclusive. Two examples give a concrete illustration of the role that initialization plays in keeping the output of a fractional-order integrator at zero once it has been driven to zero. The implications of these results are considered, with special consideration given to the formulation of the fractional-order optimal control problem.
Embeddable Mobile-C for Runtime Support of Code Mobility in Multi-Agent Systems
Authors: Chou Yu-Cheng , Ko David , Cheng Harry H.
Published: May 2009

Agent technology is emerging as an important concept for the development of distributed complex systems. A number of mobile agent systems have been developed in the last decade. However, most of them were developed to support only Java mobile agents. Furthermore, many of them are standalone platforms. In other words, they were not designed to be embedded in a user application to support the code mobility. In order to provide distributed applications with the code mobility, this article presents a mobile agent library, the Mobile-C library. The Mobile-C library is supported by various operating systems including Windows, Unix, and real-time operating systems. It has a small footprint to meet the stringent memory capacity for a variety of mechatronic and embedded systems. This library allows a Mobile-C agency, a mobile agent platform, to be embedded in a program to support C/C++ mobile agents. Functions in this library facilitate the development of a multi-agent system that can easily interface with a variety of hardware devices.
On Selecting Assumed Modes in a Controlled Articulated Flexible Multibody Dynamics System
Authors: Mordfin Theodore G. , Tadikonda Sivakumar
Published: May 2009

The modeling and simulation of controlled-articulation flexible multibody dynamic systems often involves the use of approximating functions, or assumed modes, to represent the structural characteristics of the constituent component bodies. However, clear and complete guidance on appropriate component body modeling techniques is lacking. As a result, researchers and applications engineers encounter severe and unexplained numerical problems when simulating such systems. Earlier studies demonstrated these problems, explained their causes, and developed modeling guidelines from the perspective of accuracy, robustness, and simulation efficiency. In this study, the guidelines are tested and confirmed for a controlled-articulation flexible multibody dynamic system. In support of this effort, exact closed-form and numerical solutions are developed for the small elastic motions of a planar, flexible, two-link system in which each link is represented by an Euler-Bernoulli bar in transverse vibration. The inboard link is pinned to the ground, and the outboard link is pinned to the outboard end of the first link in an arbitrary configuration. Articulation is controlled by proportional and proportional/derivative feedback control laws. The exact solutions are “truth models” for the linear characteristics of an analogous non-linear large articulation model in which link deformations are represented by assumed modes. Using a linearized version of the non-linear large-articulation model as an assumed modes testbed, the modeling guidelines are tested against the exact solutions. The numerical results conform with expectation, and the efficacy of the guidelines is successfully confirmed.
A Mobile Agent-Based Framework for Flexible Control of Multi-Robotic Systems
Authors: Nestinger Stephen S. , Chen Bo , Cheng Harry H.
Published: May 2009

Modern manufacturing systems are increasingly becoming highly dynamic due to rapid changes in market and government regulations, as well as the integration of emerging technologies. To address the challenges of uncertainty, a flexible platform is critically needed for developing a new generation of manufacturing systems. This paper presents a mobile agent-based framework that supports dynamic deployment of control algorithms and operations in multi-robotic systems. The framework is based on a mobile agent system called Mobile-C. It uses Ch, an interpretive C/C++ environment, for robot programming. Since Ch has been ported to most existing computer platforms, the framework can control robots that work in different operating systems. Using a robot package in Ch as a middleware, control programs are portable to heterogeneous robots and associated mechatronic devices. The presented framework has been implemented and validated in an experimental robotic cell that consists of a Puma 560, an IBM 7575, and a conveyor system. The results show that the mobile agent approach can effectively deploy and execute new control algorithms and operations as mobile agents on any sub-system in a network.
Embedding a C/C++ Interpreter Into Virtual Instruments for Script Blocks
Authors: Duan Hong , Cheng Harry H.
Published: May 2009

Virtual Instruments (VIs) are popularly used for testing, measurement, simulation, and control of instruments and mechatronic systems. A virtual instrument is typically programmed using graphical icons, called a G language. Although using graphical icons is simple and easy, it is quite inefficient for development of applications with special requirements and operations which have not been implemented in advance in a VI. It would be desirable to combine the ease of use of the G language with traditional programming for development of complicated applications in VI. This paper describes the design, implementation and application of embedding a C/C++ interpreter into a VI for scripting blocks in C/C++. With a C/C++ interpreter enabled VI, complicated algorithms and operations can be achieved using a script code associated with a graphical icon called the C script block. The ideas are illustrated by embedding a C/C++ interpreter into a LabVIEW platform through both techniques of code interface node (CIN) and dynamic link library (DLL) available for interfacing external programs in LabVIEW. The application of script blocks in VI is illustrated by the harmonic wavelet analysis for the vibration of a traffic detection system on the highway. Embedding a C/C++ interpreter into VIs has a great potential for enhancing the VIs with easy programmability for handling complicated applications.
Using Flexible Constraints to Reduce Noise in Multibody Systems With Intermittent Contact
Authors: Cherry Michael S. , Ross Brant A.
Published: May 2009

The application of multibody dynamics software has extended to mechanical systems with hundreds of bodies and/or hundreds of contacts. Examples include gear trains, chains on sprockets and guides, belts on pulleys, and flexible body meshes in contact with each other. These types of models frequently have intermittent contacts and contact friction that can be the source of numerical noise. This noise produces large and rapidly fluctuating force outputs that may concern the engineer, particularly when attempting to design a component or perform a failure analysis. Rigid joints are often selected to constrain the bodies undergoing intermittent contact in order to minimize the degrees of freedom (DOFs) in the model. This paper demonstrates that the use of properly-tuned flexible constraints (bushings) and contacts can significantly reduce the noise in simple and complex models with intermittent and reversing contact.
Experimental Observations of Nonlinear Nonplanar Oscillations of a Cantilever Beam
Authors: Arafat Haider N. , Nayfeh Ali H. , Hammad Bashar K.
Published: May 2009

The dynamics of a thin cantilever beam undergoing combined torsion and bending vibrations are examined experimentally. The beam’s fundamental natural frequencies in the two orthogonal bending motions and in torsion are fv1 = 5.719 Hz, fw1 = 189.730 Hz, and fφ1 = 138.938 Hz, respectively. A base-excitation shaker imparts a harmonic load that acts parallel to the width of the beam. First, the response of the beam is examined when the excitation frequency is equal to the fundamental torsion natural frequency (i.e., f = 138.9 Hz). For low levels of excitation, the motion consists mainly of hardly noticeable twisting vibrations. For high levels of excitation, the energy of the first torsion mode excites the first out-of-plane bending mode. In this case, the beam responses exhibit modulated vibrations containing both high-frequency and low-frequency components. Second, the beam is excited at the frequency f = 132.0 Hz, which is in the neighborhood the difference of these two natural frequencies. For large excitation levels, the beam vibrates with large-amplitude out-of-plane bending motions that exhibit chaotically intermittent behaviors.
A New Variable Fidelity Optimization Framework Based on Model Fusion and Objective-Oriented Sequential Sampling
Authors: Xiong Ying , Chen Wei , Tsui Kwok-Leung
Published: May 2009

Computational models with variable fidelity have been widely used in engineering design. To alleviate the computational burden, surrogate models are used for optimization without recourse to expensive high-fidelity simulations. In this work, a model fusion technique based on Bayesian Gaussian process modeling is employed to construct cheap, surrogate models to integrate information from both low-fidelity and high-fidelity models, while the interpolation uncertainty of the surrogate model due to the lack of sufficient high-fidelity simulations is quantified. In contrast to space filling, the sequential sampling of a high-fidelity simulation model in our proposed framework is objective-oriented, aiming for improving a design objective. Strategy based on periodical switching criteria is studied which is shown to be effective in guiding the sequential sampling of a high-fidelity model towards improving a design objective as well as reducing the interpolation uncertainty. A design confidence (DC) metric is proposed to serves as the stopping criterion to facilitate design decision making against the interpolation uncertainty. Numerical and engineering examples are provided to demonstrate the benefits of the proposed methodology.
Novel Motion-Doubling Linkage Mechanisms for Vehicle Suspension: Performance Simulation Results
Authors: Rastegar Jahangir , Feng Dake
Published: May 2009

In recent studies, a new class of planar and spatial linkage mechanisms was presented in which for a continuous full rotation or continuous rocking motion of the input link, the output link undergoes two continuous rocking motions. Such linkage mechanisms were referred to as the “motion-doubling” linkage mechanisms. This class of mechanisms was also shown to generally have dynamics advantage over regular mechanisms designed to achieve similar gross output motions. In a recent study, the application of such motion-doubling linkage mechanisms to vehicle suspension system was investigated. In the present study, the performance of a vehicle using such a suspension system is compared to a suspension system regularly used in vehicles. For a typical set of vehicle and tire parameters, the parameters of both suspension systems are optimally determined with a commonly used objective function. The performance of the two systems in the presence of various input disturbances is then determined using computer simulation. It is shown that suspension systems constructed with motion-doubling linkage mechanisms can provide a significantly superior performance as compared to a commonly used suspension system.
Nonlinear Dynamics of Planetary Gears With Equal Planet Spacing
Authors: Bahk Cheon-Jae , Parker Robert G.
Published: May 2009

Planetary gears are parametrically excited by the time-varying mesh stiffness that fluctuates as the number of gear tooth pairs in contact changes during gear rotation. The resulting vibration causes tooth separation leading to nonlinear effects such as classical jump phenomena and sub- and superharmonic resonance. The nonlinear dynamics of the planetary gear is examined by both numerical and analytical methods over the meaningful mesh frequency ranges. Concise, closed-form approximations for the dynamic response are obtained by perturbation analysis. The analytical solutions give insight into the nonlinear dynamics and the impact of system parameters on dynamic response. The harmonic balance method with arclength continuation confirms the perturbation solutions. The accuracy of the analytical and harmonic balance solutions is validated by parallel finite element and numerical integration simulations.
Active Roll Control of Heavy Single Unit Vehicles Employing MEMS Angular Rate Sensors
Authors: Asokanthan Samuel F. , Tian Ye , Wang Tianfu
Published: May 2009

The present paper is concerned with the use of active roll control to improve the roll stability of heavy road-vehicles and the application of Micro-electro-mechanical System (MEMS) angular rate sensors in the feedback monitoring. For this purpose, mathematical models that represent the roll/yaw dynamics for a torsionally rigid Single Unit Vehicle (SUV) is presented. The state-space models that represent the vehicle dynamics are also developed for the purpose of performing numerical simulations. A linear Quadratic Gaussian (LQG) based controller, using Kalman estimator to estimate certain states, is employed to design a full-state active roll control system. A mathematical model that represents the dynamic behavior of a low-cost MEMS gyroscope is derived for the purpose of investigating the suitability of applying this class of angular rate sensor in the roll control of heavy vehicles. Some reliability issues related to MEMS sensors, such as noise and drift, are introduced and included in vehicle dynamic models.
Mesh Phasing Relations of General Compound Planetary Gears
Authors: Guo Yichao , Parker Robert G.
Published: May 2009

This paper systematically studies the mesh phase relations of general compound planetary gears. The mesh phase relations are described by the relative phases between mesh tooth variation functions of all gear meshes. The analysis allows for the fact that compound planetary gears may have gear meshes with different mesh periods. A numbering method is proposed for the accurate definitions of the relative phases in a general compound planetary gear. The phases of all gear meshes relative to the base referred mesh are calculated analytically. Important relations among these relative phases are also studied. The results from this study are important for the clarification of the mesh phasing properties of general compound planetary gears, and they are necessary for the dynamic analysis of compound planetary gears, which involves time-varying mesh stiffnesses.
Sensitivity of General Compound Planetary Gear Natural Frequencies and Vibration Modes to Model Parameters
Authors: Guo Yichao , Parker Robert G.
Published: May 2009

This paper studies sensitivity of general compound planetary gear natural frequencies and vibration modes to all inertia and stiffness parameters. The results are expressed in compact formulae for tuned and mistuned compound planetary gears. Analysis reveals that for tuned (i.e., cyclically symmetric) compound planetary gears, eigenvalue sensitivities to stiffness parameters are directly proportional to modal strain energies, and eigenvalue sensitivities to inertia parameters are proportional to modal kinetic energies. Furthermore, the eigenvalue sensitivities to all model parameters are determined by inspection of the modal strain and kinetic energy distributions for a given mode. For mistuned systems, the results differ for the cases of tuned one mistuned parameter, two or more independent mistuned parameters, and two or more dependent mistuned parameters. For cases of one mistuned parameter, and two or more independent mistuned parameters, compact formulae of eigensensitivities are derived, and they are proportional to modal strain/kinetic energies. For the case of two or more dependent mistuned parameters, however, only general expressions of eigensensitivities are derived. These eigensensitivities depend not only on modal energies, but also on how the dependent mistuned parameters are related. Hence inspection of modal energies alone may fail to locate the parameter that is most effective in tuning natural frequencies.
Relative Motion Emulating Robotic System as a Test Bed for Aerial Refueling Using VISNAV and Mobile Stewart Platforms
Authors: Cho Changhwa , Junkins John
Published: May 2009

This paper describes a relative motion emulating robotic system (RMERS) which is made up with a vision navigation (VISNAV), a novel method for proximity navigation and mobile Stewart platforms, parallel manipulators to have six degrees of freedom. The RMERS is a ground-based test bed for aerial refueling and enables already simulated results to physically demonstrate their performance in a ground level. The scope of REMES can reach any relative dynamical system which requires experimental tests. This paper presents theoretical introduction prior to making REMES tangible in the lab. The VISNAV system and the kinematics and dynamics of the Stewart platform will be shortly introduced and dynamical mapping from aerial refueling to mobile Stewart platforms will be given. Finally, some numerical results are simulated.
Characteristics and Optimization of Series Multiple Tuned-Mass Dampers
Authors: Zuo Lei
Published: May 2009

Tuned-mass damper (TMD), or dynamic vibration absorber (DVA), is a very practical and effective device for vibration suppression. Various types of tuned-mass dampers have been proposed in literature, including the classic TMD, (parallel) multiple TMDs, multi-degree-of-freedom (DOF) TMD, and three-element TMD. In this paper we study the characteristics and optimization of a new type of TMD system, in which multiple absorbers are connected to the primary system in series. Structured H2 and H∞ control methods are adopted to optimize the parameters of spring stiffness and damping coefficients for random and harmonic vibration. It is found that series multiple TMDs are more effective and robust than all the other types of TMDs of the same mass ratio. The series two TMDs of total mass ratio 5% can appear to have 31%–66% more mass than the classical TMD, and it can perform better than parallel ten TMDs of the same total mass ratio. The series TMDs are also less sensitive to the parameter changes of the primary system than other TMD(s). Unlike the parallel multiple TMDs, the optimal mass distribution among absorbers in series TMDs is far from the case of equal masses, but instead the first absorber mass is much larger than the second one. Similar to the two-DOF TMD, the optimal series two TMDs also have zero damping in one of its two connections and further increased effectiveness can be obtained if negative dashpot is allowed.
Influence of Tensioner Dry Friction on the Vibration of Belt Drives With Belt Bending Stiffness
Authors: Zhu Farong , Parker Robert G.
Published: May 2009

A model of dry friction tensioner in a belt-pulley system considering transverse belt vibration is developed, and the influence of the dry friction on the system dynamics is examined. The discretized formulation is divided into a linear subsystem including linear coordinates and a nonlinear subsystem addressing tensioner arm vibration, which reduces the dimension of the iteration matrices when employing the harmonic balance method. The Coulomb damping at the tensioner arm pivot mitigates the tensioner arm vibration but not necessarily the vibrations of other system components. The extent of the mitigation varies for different excitation frequency ranges. The critical amplitude of the dry friction torque beyond which the system operates with a locked arm is determined analytically. Superharmonic resonances are observed in the responses of the generalized span coordinates but their amplitudes are small. The energy dissipation at the tensioner arm hub is discussed, and the stick-slip phenomena of the arm are reflected in the velocity reversals near the arm extreme location. Dependence of the span tension fluctuations on Coulomb torque is explored.
Piece-Wise Linear Dynamic Analysis of Serpentine Belt Drives With a One-Way Clutch
Authors: Zhu Farong , Parker Robert G.
Published: May 2009

A prototypical three-pulley serpentine belt drive with belt bending stiffness is extended to include a one-way clutch in order to understand the nonlinear dynamics of the system with the one-way clutch performance. The clutch is modeled based on the relative velocity of the driven pulley and its accessory. The clutch locks (engages) the pulley and accessory for zero relative velocity and produces a positive inner clutch torque. Zero clutch torque initiates clutch disengagement, allowing unequal velocities of the two components. This model leads to a piece-wise linear system. The transition matrix is used to evaluate the system response in discrete time series for the two linear configurations, saving significant computation time. The system dynamics including response and dynamic tension drop are examined for varying excitation frequency, inertia ratio of the pulley and accessory, and external load. The investigation of vibration reduction due to the single-direction power transmission of the clutch provides design guidelines in practice.
Pseudo-Hierarchical Multistage Model for System of Systems Design and Operations
Authors: Kim Harrison M. , Hidalgo I. Jessica
Published: May 2009

This paper describes a multilevel, multistage approach to system of systems design optimization where a system design is linked with system allocation along the multistage decision making horizon. The approach is composed of two parts: pseudo-hierarchical formulation (i.e., how to model the stages of multiple, separate decision making processes), and multistage coordination (i.e., how efficiently the proposed model would perform). The pseudo-hierarchical formulation integrates multilevel optimization and multistage programming to capture level-by-level and stage-by-stage system design optimization. The multistage coordination is based on the alternating directions method that is incorporated as an efficient means to solve this inherently largescale optimization problem. An example on collaborative system operation and design between an airline and an aircraft manufacturer validates the methodology where an airline plans to introduce multiple new aircraft to capture dynamically changing demand of the customers. The proposed methodology is validated against the all-in-one approach and the sequential approach.
Energy Scavenging for Wireless Sensor Networks
Authors: Xue Xin , Gonzalez-Argueta Luis , Sundararajan V.
Published: May 2009

Conventional condition monitoring of electrical machinery is conducted by measuring signals such as currents and vibrations outside the motor. Wireless sensors now provide a means of accessing and measuring useful signals inside the motor where the phenomena responsible for failure occur. These sensors are capable of not merely sensing, but also processing, storage and eventually communication. Since all these activities require power that is supplied conventionally by batteries, the useful life of the sensor node is limited by the life of the battery. This paper describes the design of an energy scavenger capable of collecting energy from the fringing field in a three-phase induction motor. The field in the magnetic filed is converted to electrical energy for use in intelligent wireless sensor nodes. The alternating magnetic field in a three phase induction motor is first measured by the hall-effect sensors. A coil wound on a ferrite core harvests the leaked energy. The experimental results are compared to the theoretical calculations of induced voltage. The paper describes results from tests conducted with a prototype coil that is used to power wireless sensor nodes in a motor running at full speed.
Random Vibration Suppression of Non-Uniform Curved Beams Using Optimal Tuned Mass Damper
Authors: Yang F. , Sedaghati R. , Esmailzadeh Ebrahim
Published: May 2009

Beam type structures have many applications in mechanical, aerospace and civil engineering fields. Due to low damping and recent trend for light weight design (especially for aerospace vehicles and transportation systems), these structures may easily vibrate in their low natural frequencies which may subsequently lead to failure of structure. Thus vibration control of these structures is a very important task which should be considered in preliminary structural design optimization. One of the engineering concerns is to design non-uniform beam type structures with changing geometry. In this study, the structural vibration analysis and design of a curved beam with attached tuned mass dampers under random excitations are presented. The finite element formulation of the curved beam with attached tuned mass dampers has been derived and combined with Sequential Quadratic Programming optimization algorithm to find optimal design variables in tuned mass dampers to minimize the vibration. Illustrative examples are provided to demonstrate the methodology.
Application of Independent Component Analysis for Sound Source Separation
Authors: Tan Chin An , Gupta Arvind , Li Shaungqing
Published: May 2009

In this paper, experiments on the application of the independent component analysis (ICA) technique to separate unknown source signals are reported. ICA is one of the fastest growing fields in signal processing with applications to speech recognition systems, telecommunications, and biomedical signal processing. It is a data-transformation technique that finds independent sources of activity from linear mixtures of unknown independent sources. The statistical method to measure independence is to find a linear representation of the non-Gaussian data so that the components are as independent as possible and the mutual information between them is minimum. Although extensive simulations have been performed to demonstrate the power of the learning algorithm for the problems of instantaneous mixing and un-mixing of sources, its application to the noise diagnosis and separation in an industrial setting has not been considered. Noise separation in machinery has a strong basis in the “cocktail problem” in which it is difficult to separate/isolate the voice of a person in a room filled with competing voices and noises. The experiments conducted consist of separating several artificially generated sources of noise. Our results demonstrate that ICA can be effectively employed for such kinds of applications. The underdetermined problem in which there are fewer sensors than sources in the ICA formulation is also examined by applying a time-invariant linear transformation of the acquired signals to identify a single source.
What Skills Will Future Engineering Graduates Need in Global Organizations?
Authors: Hayes C. C. , Pande A.
Published: May 2009

The globalization of the marketplace is rapidly transforming business organizations, the nature of the products they sell, product design teams, and the skills and knowledge required to operate effectively in this environment. These changes include global distribution of talent within international organizations, an increasing reliance on virtual collaboration in design teams, greater need to make usable products, and the rise of new markets in emerging economies which have very different needs from tradition markets. This paper discusses the additional knowledge and skills engineers will need to succeed in global organizations, how these skills may be introduced into curricula, and challenges in making these changes. While change is difficult, educational organizations that can do so rapidly will become leaders in future engineering education.
Study on Product Life-Cycle Genetic Engineering Theory
Authors: Huang Kezheng
Published: May 2009

Widespread IT application leads up to the idea of integrating all the information related with products. It is the ultimate goal to design a product creatively and automatically acquiring all the updated information through close interaction with Product Life-cycle Management (PLM) system starting from conceptual design phase. In this paper, Product Genetic Engineering (PGE) concept for innovative design automation is introduced, and extended to Product Life-Cycle Genetic Engineering (PLCGE) which has genes for downstream processes and can interact with all the real-time information through PLM, and so provides real-time support for PGE decision-making. A basic framework for PLCGE is proposed in which the product development can be divided into two main phases: the generation of product “genome” and the growth of the “genome” into its physical form. In the former phase, the product genome originates from and serves as an extension to human genome, and forms a complete genome through design process dealing with life-cycle factors. In the latter phase, the product genome acquires “protein” to grow inside its mother body (the factory), and PLM system acts as an “umbilical cord” between the product genome and its mother body. Finally, a case study of PLCGE application in Mass Customization is made for validity of PLCGE.
A Novel Structure for Cantilever-Beam MEMS Power Generator
Authors: Wang Jun , Chang Scott , Tan Chin An , Auner Greg
Published: May 2009

A novel cantilever-beam type MEMS power generator is proposed for the conversion of vibration mechanical energy to electrical energy through piezoelectric effects. In the various MEMS-based micro power generating schemes, piezoelectric conversion usually achieves a higher efficiency than that of electromagnetic or electrostatic schemes. Currently, most cantilever-beam type MEMS power generators are suitable for harvesting energy in relatively high frequency ranges (500 Hz to 14 kHz), but are not effective in harvesting low frequency (<10 Hz) vibration energy, such as energy from human walking or ocean wave, for which MEMS power generators are most desired. In this paper, a new cantilever-beam MEMS power generator is proposed, which can greatly improve the power conversion for low frequency circumstances. The power generator consists of two sets of cantilever beams: 1. A properly designed mm-size cantilever-beam with metal as the proof mass, and having low resonant frequency matching that of the external low frequency excitation sources. This is to be used to effectively couple the external motion. 2. An array of micro thin film piezoelectric (PZT) cantilever-beams, each with metal as proof mass, and having higher resonant frequencies. The external excitation is coupled to the single cantilever beam with kinetic energy. Through impact between the mm-size cantilever beam (low frequency) and the micro cantilever beam array (high frequency), the coupled mechanical energy is transferred to electrical energy through piezoelectric effect. Simulation results show that energy conversion efficiency can be greatly improved by using such a coupled structure as compared to that of only using MEMS cantilever beams with high frequency or a single mm-size beam structure. This may have a wide range of applications in pervasive computing and biomedical engineering.
Algorithms for Bayesian Model Class Selection of Higher-Dimensional Dynamic Systems
Authors: Cheung Sai Hung , Beck James L.
Published: May 2009

In recent years, Bayesian model updating techniques based on measured data have been applied in structural health monitoring. Often we are faced with the problem of how to select the ‘best’ model from a set of competing candidate model classes for the system based on data. To tackle this problem, Bayesian model class selection is used, which provides a rigorous Bayesian updating procedure to give the probability of different candidate classes for a system, based on the data from the system. There may be cases where more than one model class has significant probability and each of these will give different predictions. Bayesian model class averaging provides a coherent mechanism to incorporate all the considered model classes in the probabilistic predictions for the system. However, both Bayesian model class selection and Bayesian model class averaging require the calculation of the evidence of the model class which requires the nontrivial computation of a multi-dimensional integral. In this paper, several methods for solving this computationally challenging problem of model class selection are presented, proposed and compared. The efficiency of the proposed methods is illustrated by an example involving a structural dynamic system.
A Selection Framework for Derivative Products
Authors: Rojas Alvaro J. , Esterman Marcos , Wesline Jeanne M. , McLaughlin Matthew R. , Goldstein Carol-Lynn
Published: May 2009

Firms today increasingly seek to leverage product platforms via derivative product versions of the base platform, but successfully doing so is a significant challenge. Numerous enablers are required, such as robust product development processes, effective and well trained organizations, R&D activities that are aligned to support product strategies, and a clearly defined corporate strategy. In derivative product development firms struggle to identify the optimum derivatives to develop and bring to market. Evaluating which feature to improve upon, which technologies to incorporate, which markets to pursue, and ultimately which derivative product to develop is an uncertain proposition that has significant implications to future profitability. There majority tools and processes that exist to provide guidance in these activities largely focus on platform development strategies and decisions. A limited number are known to apply specifically to derivative products, after the platform has been design and implemented. This work proposes a derivative product concept generation and selection framework that extends the design for variety methodology to analyze derivative product alternatives.
The Realization of the “SFT” and “HFT” Method on the CNC Hypoid Cutting Machine
Authors: Liu Huran , Liu Quanhong , Zhao Dongfu , Song Deyu , Wang Jiande
Published: May 2009

The “SFT” and “HFT” is a highly effective means of generating spiral-bevel and hypoid gears. The current paper presents a method for realizing, and indeed improving, the conventional gear cutting method associated with a traditional machine tool upon a CNC Hypoid Cutting Machine.
A Framework for Designing Balanced Product Platforms by Estimating Versatility of Components
Authors: Kang Chang Muk , Hong Yoo Suk
Published: May 2009

Mass customization is a common trend in industries and platform-based product family strategy is widely used for an efficient mass customization. While commonization of a platform is a viable mean for reducing the customization cost, it also has a risk of losing some market share due to its limitation on differentiating individual products. This trade-off requires a platform to be balanced between commonality and distinctiveness of products. In this paper, we focus on developing a versatile platform that maximizes the use of common components while facilitating differentiations which are highly effective for increasing the market share of a product family. A versatile platform is comprised of versatile components which do not restrict effective differentiations even if it is commonized. To determine a certain component is versatile or not, we considered which specifications are preferred to be differentiated in the market and how much change would be required for the component to differentiate a specification. With these two measures, we define a versatility index representing how versatile a component is. Components with higher versatility values are appropriate to be platformized since they are less likely to be changed for differentiations. Furthermore, identification of non-versatile components may provide a clue for improving architecture of the product. The proposed method is applied to the PC mouse design, which yields reasonable alternatives for platform design.
Kinematics and Dynamics of a 3-CRU Spherical Parallel Robot
Authors: Callegari Massimo , Cammarata Alessandro , Gabrielli Andrea , Sinatra Rosario
Published: May 2009

This paper describes the kinematics and dynamics of a spherical parallel wrist called 3-CRU after the topology of its legs. After a mobility analysis showing the geometrical conditions that yield motions of pure rotation, its kinematics is worked out in closed-form for both position and velocity problems. Then inverse and direct dynamics models are developed and the latter is investigated by the use of the multibody NOC method. Seven bodies are considered by the models: two links for each one of the three legs and the moving platform, while inertial joints parameters have been neglected. Finally, numerical simulations are presented to validate the model. This architecture adopts kinematic pairs that make it suitable for being realized at a mini- or microscale. The Authors are presently developing the design of a robot based on such a concept.