bluuebunny/crossref_metadata_2025 huggingface dataset:
Chaos Properties of a Rotor System With Nonlinear Hydro-Static Bearings
Authors: Chen Changping , Dai Liming
Published: May 2009

General motions of discs and shafts of large rotary machines appear with highly nonlinear behavior. The geometries of the shafts and the supporting systems of this machine can all be treated as nonlinear. This paper aims to investigate the chaos properties of the nonlinear rotating system. The nonlinear dynamic governing equations of the rotating bearing system are derived. The geometric nonlinearity of the shaft, nonlinear hydrostatic forces of the bearings, mass of the shaft and disc, deformation of the shaft and a disc mounted on the shaft, and the viscoelasticity of the supports are all taken into account. Numerical simulations are performed in the research for studying the bifurcation and chaos properties of the specified nonlinear rotating system. The effects of the shaft’s rotating speed and the mass eccentricity of the disc on the nonlinear dynamic properties of the system are investigated in detail. The results show that abundant of bifurcations and chaos exist in this nonlinear rotating system Corresponding to certain parameter values. The bifurcations and chaotic phenomena should be avoided when designing the rotating system by adjusting the design parameters. The results of this research can hereby be used for guiding the design and operation of rotor-bearing systems.
Reverse Kinematic Analysis of the Spatial Six Axis Robotic Manipulator With Consecutive Joint Axes Parallel
Authors: Mckinley Javier Rolda´n , Crane Carl , Dooner David B.
Published: May 2009

This paper introduces a reconfigurable one degree-of-freedom spatial mechanism that can be applied to repetitive motion tasks. The concept is to incorporate five pairs of noncircular gears into a six degree-of-freedom closed-loop spatial chain. The gear pairs are designed based on the given mechanism parameters and the user defined motion specification of a coupler link of the mechanism. It is shown in the paper that planar gear pairs can be used if the spatial closed-loop chain is comprised of six pairs of parallel joint axes, i.e. the first joint axis is parallel to the second, the third is parallel to the fourth, …, and the eleventh is parallel to the twelfth. This paper presents the detailed reverse kinematic analysis of this specific geometry. A numerical example is presented.
Study on the Noise Source Identification Based on a Novel Variable Step-Size Algorithm of Blind Sources Separation
Authors: Zhang Linke , He Lin , Jiang Yong
Published: May 2009

Some preknowledge of sources input signals or transmission paths were required in advance for traditional noise source identification. In this paper, a novel variable step-size algorithm of blind source separation (BSS) is proposed to identify noise source, which doesn’t need any preknowledge but some statistical assumptions about sources. Most BSS algorithms have been issued on fixed step-size, relatively little work has been focused on variable step-size. The output feedback of step-size update in the proposed algorithm is derived from the analysis of adaptive blind sources separation and adaptive filter. With the natural gradient algorithm based minimum mutual information, the iteration formula of separate matrix is also obtained. The availability of this algorithm is confirmed by simulations. Namely, the convergence rate of this algorithm is rapid, while ensuring low steady-state error.
Improving Confidence in Simulation-Based Design Through Error Functions
Authors: Goh Yee Mey , McMahon Chris , Booker Julian
Published: May 2009

Understanding of uncertainty in the data and models used in design simulations matures during the design process as the design progresses from vague requirements through to its full embodiment and detail. Failure to take account of uncertainty in the information that is used in and generated from simulation processes poses risks to decisions based upon these. This paper presents a classification scheme based on the extent and nature of uncertainty in the correlations between simulation predictions and the evidence for a specific performance criterion. The classification allows development of a confidence scale and associated error functions for characterizing the discrepancy between the correlations of design performance parameters and evidence, in the presence of uncertainty. Together, the confidence scale and error functions may provide a greater understanding of uncertainty and errors in simulation processes. In the context of parametric design, the approach provides a mechanism for building up greater understanding of the simulation performance across a feasible design space. A case study on the design of shrink-fits is used to illustrate the framework for handling uncertainty in a systematic and organized manner. The theoretical and practical limitations and further work will be discussed.
Robustness Analysis of Optimally Designed Feedback Control of Linear Periodic Systems With Time-Delay
Authors: Zhang Jie , Sun Jian-Qiao
Published: May 2009

In this paper, we present an application of a semi-discretization method to the stability and robust analysis of optimally designed PID feedback control of a periodic linear system with time delay. The semi-discretization method uses a mapping of the system response in a finite-dimensional state space. Minimization of the largest absolute value of the eigenvalues of the mapping leads to optimal control gains. The robust analysis examines the stability region of system parameters with modeling errors when the control gains are set to be the optimal ones. Extensive numerical examples of stability regions are presented in the paper.
Concepts and Tools for the Test of the Communication Sub-System of Time-Triggered Distributed Embedded Systems
Authors: Horauer Martin , Armengaud Eric , Steininger Andreas
Published: May 2009

With the adoption of FlexRay, the time triggered paradigm has been widely accepted by the automotive industry as a means to tackle the requirements of future automotive electronics. However, when compared with traditional event-triggered systems like CAN, the benefits of higher reliability come at the cost of increased complexity during system design. In fact, to support the development of these systems adequate tool-support will be mandatory. In this paper we discuss the requirements and concepts for and present an implementation of a test and diagnosis toolset for FlexRay-based automotive distributed networks. Next to data monitoring and recording, this toolset provides facilities for fault injection and replay. Hence, the presented implementation is tailored for an embedded test and fault diagnosis and will enable an assessment of the reliability and dependability of future automotive solutions.
Solving Kinematics and Active Forces of Some Parallel Manipulators by a Block Diagram Modeling System
Authors: Lu Yi , Hu Bo
Published: May 2009

A novel CAD approach is proposed for analyzing kinematics and dynamics of spatial parallel manipulators by using a block diagram modeling system in Simulink/SimMechanics. First, some basic concepts, common modeling and simulation techniques of block diagram modeling system are described. Second, the block diagram modeling systems of various active limbs and their equivalent sub-systems are built, and the simulation mechanisms and the whole block diagram modeling systems of the 2UPU+SPR and 3SPS+SP parallel manipulators with 3, 4-dof are created. Third, the pose, the velocity, the acceleration as well as the active forces of the parallel manipulators are solved. This project is supported by NSFC (Nature Science Fund of China) 50575198.
On Multiple Hopf Bifurcations of Airflow Excited Vibration of a Translating String
Authors: Wang Yuefang , Lu¨ Lefeng , Liu Yingxi
Published: May 2009

This paper presents the stability and bifurcation of transverse motion of translating strings excited by a steady wind flowfield. The stability of the equilibrium configuration is presented for loss of stability and generation of limit cycles via the Hopf bifurcation. It is demonstrated that there are single, double and quadruple Hopf bifurcations in the parametric space that lead to the limit cycle motion. The method of Incremental Harmonic Balance is used to solve the limit cycle response of which the stability is determined by computation of the Floquet multipliers. For the forced vibration, it is pointed out that the periodic and quasi-periodic motions exist as parameters are changed. The quench frequency and the Neimark-Sacker (NS) bifurcation and flip bifurcation are obtained. The continuity software MATCONT is adopted and the Resonance 1:1, 1:3 and 1:4 as well as NS to NS bifurcations are presented. The bifurcation behavior reveals the complexity of the string’s motion response induce by aerodynamic excitations.
FEM Stress Analysis and Strength of Adhesive-Rivets Combination Joints Under Tensile Shear Loadings
Authors: Sawa Toshiyuki , Nogaito Ryo
Published: May 2009

Stress distributions in adhesive-rivets combination joints under tensile shear loadings are analyzed using a three-dimensional finite element method. The effects of the adherend thickness, the number of rivets and the rivet locations on the stress distributions at the interfaces are examined. Experiments to measure the rupture loads of the joints were carried out. As the results, it was found that the peel stress near the edges of the interfaces decreased as the adherend thickness increased. The maximum value of the maximum principal stresses near the edges of the interfaces decreased as the interval between the two rivets in the longitudinal direction decreased in the case where two rivets were combined. However, small effect of the interval between the two rivets in the lateral direction was found in the case of two rivets. The maximum value of the maximum principal stresses near the edges of the interfaces decreased as the interval between the four rivets in the longitudinal direction decreased and that in the lateral direction increased in the case where four rivets were combined. Discussion on the rupture loads of adhesive-rivets combination joints was made. The rupture loads of the joints increased as the number of rivets increased. The rupture loads of the adhesive-rivets combination joints could be increased more than those of only-riveted joints in the case of two rivets. The rupture loads of adhesive-rivets combination joints were found to be almost the same as those of only-riveted joints in the case of four rivets.
Longitudinal Study of Learning Outcomes in a New Product Development Class
Authors: Cobb Corie L. , Agogino Alice M. , Beckman Sara L.
Published: May 2009

This paper reports on a longitudinal study of lessons learned from a graduate-level New Product Development course taught at the University of California at Berkeley, comparing lessons learned by students during the course with alumni perceptions one to ten years after graduation. Previous research on student learning outcomes in New Product Development (NPD) found that on the last day of class students identify working in multifunctional teams and understanding user needs as their most important lessons learned. This study raises the question of whether or not students maintain the same emphasis on learning outcomes once they have moved on to careers in industry. To answer this question, we conducted 21 in-depth interviews with alumni who took the course between 1995–2005 and are now working in industry. A qualitative and quantitative analysis of the alumni interviews reveals that former students still highly value what they learned about team work and understanding user needs, but see more value in tools for concept generation, prototyping, and testing after gaining work experience. The results reaffirm the value of engaging students in multidisciplinary design projects as a vehicle for developing the professional skills needed in today’s competitive new product development environment.
Modeling and Tracking Control System of Shape Memory Alloy Actuator
Authors: Ren B. Y. , Chen B. Q.
Published: May 2009

The different Shape Memory Alloy (SMA) actuators have been widely used in the fields of smart structures. However, the accurate prediction of thermomechanical behavior of SMA actuators is very difficult due to the nonlinearity of inherence hysteresis of SMA. Therefore, the tracking control accuracy of SMA actuator is very important for the practical application of the SMA actuator. A dynamic hysteresis model of bias-type SMA actuator based on constitutive law developed by Brinson et al. and hysteresis model developed by Ikuta et al. is presented. The control systems composed of the Proportional Integral Derivative (PID) controller as well as a fuzzy controller or a fuzzy-PID composite controller for compensating the hysteresis is proposed. The effort of tracking control system is analyzed according to the simulation on the displacement of SMA actuator with the three kinds of controllers. The result can provide a reference for the application of SMA actuator in the fields of smart structures.
Minimization of Bounded Cable Tensions in Cable-Based Parallel Manipulators
Authors: Hassan Mahir , Khajepour Amir
Published: May 2009

In this work, the application of the Dykstra’s alternating projection method to find the minimum-2-norm solution for actuator forces is discussed in the case when lower and upper bounds are imposed on the actuator forces. The lower bound is due to specified pretension desired in the cables and the upper bound is due to the maximum allowable forces in the cables. This algorithm presents a systematic numerical method to determine whether or not a solution exists to the cable forces within these bounds and, if it does exist, calculate the minimum-2-norm solution for the cable forces for a given task force. This method is applied to an example 2-DOF translational cable-driven manipulator and a geometrical demonstration is presented.
A Rigorous Dynamical-Systems-Based Analysis of the Self-Stabilizing Influence of Muscles
Authors: Eriten Melih , Dankowicz Harry
Published: May 2009

In this paper, dynamical systems analysis and optimization tools are used to investigate the local dynamic stability of periodic task-related motions of simple models of the lower-body musculoskeletal apparatus and to seek parameter values guaranteeing their stability. In particular, the dynamics of a two-link model of a leg undergoing periodic excitation through one or several contractile muscle elements corresponding to a simple knee-bending motion is studied. Several muscle models incorporating various active and passive elements are included and the notion of self-stabilization of the rigid-body dynamics through the imposition of muscle-like actuation is investigated. It is found that self-stabilization depends both on muscle architecture and configuration as well as the properties of the reference motion. Additionally, antagonistic muscles (flexor-extensor muscle couples) are shown to enable stable motions over larger ranges in parameter space and that even the simplest neuronal feedback mechanism can stabilize the repetitive motions. The work provides a review of the necessary concepts of stability and a commentary on existing incorrect results that have appeared in the literature on muscle self-stabilization.
Synthesis of the Body Swing Rotator Joint Aligning Mechanism for the Abductor Joint of a Novel Tripedal Locomotion Robot
Authors: Hong Dennis W. , Lahr Derek F.
Published: May 2009

The unique three-legged walking robot STriDER (Self-excited Tripedal Dynamic Experimental Robot) utilizes a novel tripedal gait which incorporates aspects of passive dynamic walking into a stable tripedal platform to walk efficiently, and is also capable of changing directions. This unique tripedal gait, however, requires three abductor joints to align two of the three body swing rotator joints in the body, depending on the direction of the step the robot takes. In an earlier prototype of STriDER, the three abductor joints were independently actuated using three DC motors to align the rotator joints which made the robot heavy and inefficient. In this paper, we present the synthesis, analysis, and mechanical design of a novel mechanism for actuating the three abductor joints of this unique three-legged walking robot to generate the required motion using only a single actuator. The mechanism utilizes an internal gear set to generate a Hypotrochoid path curve and uses pin-in-slot joints to coordinate the motion of the three abductor joints to guide them through the four sets of positions required to enable the robot to walk efficiently. A brief description and background of the tripedal locomotion robot STriDER is presented first, followed by the design constraints and requirements of the abductor joint mechanism. Synthesis and kinematic analysis of the mechanism is presented with a study of the force transmission characteristics for a quasi-static case. A description of the detailed mechanical design, results from the experiments, and a conclusion with a discussion for future work is presented next.
Design Optimization of a Novel Tripedal Locomotion Robot Through Simulation and Experiments for a Single Step Dynamic Gait
Authors: Heaston Jeremy R. , Hong Dennis W.
Published: May 2009

This paper presents the concept and design of a unique three-legged walking robot, and results from the simulation and experiments of a single step tripedal gait. The STriDER (Self-excited Tripedal Dynamic Experimental Robot) incorporates aspects of passive dynamic walking into a stable tripedal platform and is capable of changing directions. To initiate a step, the legs are oriented to push the center of gravity outside of the stance polygon, and as the body of the robot falls forward, the swing leg naturally swings in between the two stance legs and catches the fall. Once all three legs are in contact with the ground, the robot regains its stability and the posture of the robot is then reset in preparation for the next step. The changing of the direction is done by a unique way of changing the sequence of which of the three legs is the swing leg. To guide the design of the robot, a dynamic model was developed and a simulation of a single step tripedal gait was performed to allow for tuning of several design parameters, including the mass properties and link dimensions. By considering the two stance legs as a single effective link connected to the ground, the robot can be modeled as a planar four-link pendulum in the sagittal plane. Further development of the simulation also allowed for optimization of the design parameters to create an ideal gait for the robot. A self-excited method of actuation, which seeks to drive a stable system toward instability, was used to control the robot. This method of actuation was found to be robust across a wide range of design parameters and relatively insensitive to controller gains. The design of the first prototype and result from the experiments are presented with a discussion of future work.
Development of Vehicle Dynamics Simulation for Safety Analyses of Rail Vehicles on Excited Tracks
Authors: Nishimura Kazuhiko , Terumichi Yoshiaki , Morimura Tsutomu , Sogabe Kiyoshi
Published: May 2009

Considerable numbers of earthquake disasters have been experienced in Japan. Thus the study and research of earthquake disaster prevention are highly awarded in Japan. In a railway industry, for instance, infrastructures have been reinforced and a new alert system has been employed to regulate the operating system to stop trains immediately if a great earthquake occurs. A railway is organized by a variety of individual technologies, and functions safely and properly as a system, therefore it is beneficial for the system safety to study and examine the individual potential cases of disasters caused by earthquakes from various different viewpoints. Recent reports imply that rail vehicles could derail solely by the ground motions of earthquakes without fatal damages of vehicles and tracks. Therefore, in this paper, the vehicle safety in terms of the dynamic stability and the possibility of derailment directly caused by the track excitations of great earthquakes, is specifically studied. The rail vehicles are supposed to involve severe vehicle body motions, wheel lifts and derailing behaviors. In this study, such extreme responses of the vehicles is focused on, thus at the start, a new vehicle dynamics simulation is developed with unique modeling specifically taking account of internal slide forces between the vehicle body and the bogie resulting from large motions of vehicles. Then, the simulation is employed to assess the safety of vehicles on excited tracks with sinusoidal displacements, and the numerical results are analyzed. Through the assessment and the analyses, four major outcomes are obtained. First, the limit excitation amplitudes for the wheel lift of flange height, defined as safety limits in this paper, are presented in the frequency range of 0.5 to 2.5Hz. Second, two types of critical vehicle motions are captured; one is a rocking motion involving large wheel lift observed in lower frequency excitations and the other is a severe horizontal impact of a wheel to a rail observed in higher frequency excitations. In the latter cases, the vehicles derail with slightly larger excitations than those of the wheel lift of flange height. Third, the roll characteristic of a vehicle body is demonstrated as a dominant factor for the vehicle dynamic motions in terms of large wheel lift and derailment. Finally, the unique modeling in the developed simulation is evaluated and its advantages for precise prediction of the extreme vehicle responses are confirmed.
Analog Implementation of Non Integer Order PIλDμ Controller Via Field Programmable Analog Array
Authors: Caponetto R. , Dongola G.
Published: May 2009

Recently a renewed interest has been devoted to non integer, or fractional, order systems. This is due to the fact that they well model a lot of physical systems and can be usefully applied in the area of automatic control. On drawback, mainly faced in the area of control systems, is related to their practical realization, essentially due to their infinite dimension nature. In this paper it is proposed an analog implementation of a non integer order PIλDμ controller by using Field Programmable Analog Array. The reported example shows the feasibility and reliability of the proposed approach.
Numerical Solution of Constrained Systems Using Jet Spaces
Authors: Tuomela Jukka , Arponen Teijo , Normi Villesamuli
Published: May 2009

The major difficulty in simulations of constrained systems is how to avoid drift off and spurious oscillations. We describe results obtained by our method which addresses these issues. Our computational model considers differential equations in jet spaces. In case of multibody systems we use Lagrangian formalism to derive the equations of motion. Constraints and possible invariants (like conservation of energy) are taken into account by restricting the dynamics to an appropriate submanifold of a jet space. We will consider only holonomic constraints in this paper. However, nonholonomic problems can also be formulated and solved with our method.
Second-Order Blind Identification for Operational Modal Analysis
Authors: Poncelet F. , Kerschen G. , Golinval J. C. , Marin F.
Published: May 2009

For modal analysis of large structures, it is unpractical and expensive to use artificial excitation (e.g., shakers). However, engineering structures are most often subject to ambient loads (e.g., traffic and wind) that can be exploited for modal parameter estimation. One difficulty is that the actual loading conditions cannot generally be measured, and output-only measurements are available. This paper proposes to explore the utility of blind source separation (BSS) techniques for operational modal analysis. The basic idea of BSS is to recover unobserved source signals from their observed mixtures. The feasibility and practicality of the proposed method are demonstrated using an experimental application.
New Geometry of Generating Spiral Bevel Gear
Authors: Zhou Kaihong , Tang Jinyuan , Zeng Tao
Published: May 2009

New geometry of generating spiral bevel gear is proposed. The key idea of the new proposed geometry is that the gear tooth surface geometry can be investigated in a developed curved surface based on the planar engagement principle. It is proved that the profile curve on the back of generating cone surface is a conical involute curve. The equations of generated gear tooth surface are achieved by the conical involute curve sweeping along the tooth trace of gear. The obtained equations are explicit and independent of the machine-tool settings. This differs from previous studies. The developed theory is illustrated with numerical examples to compare with the previous method, the comparison approves that the method is possible in this way. The new method indicates that there are new solutions to the design the production of spiral bevel gear.
Introduction to Engineering Through Service-Learning
Authors: Kazmer David , Duffy John , Barrington Linda , Perna Beverly
Published: May 2009

Service-learning (S-L) is the integration of academic subject matter with service to the community in credit-bearing courses. In an engineering context, service-learning provides a project-based experience in which students are presented with real clients and their problems, often of immediate need. This paper reflects on three years of service-learning integrated into a first engineering course with approximately three hundred students per year. The costs and benefits of service-learning to students, faculty, and clients are analyzed through several means including traditional teaching evaluations, blind pre- and post-assessments by students and clients, multi-year institutional data regarding student performance, and others. The results indicate that a majority of students personally believe that the described service-learning project is a valuable experience and should be integrated throughout the engineering curriculum. However, the service-learning experience varied significantly across teams, students, and course offerings.
An Analysis of the Force-Moment Capabilities of Branch-Redundant Planar-Parallel Manipulators
Authors: Nokleby Scott B. , Firmani Flavio , Zibil Alp , Podhorodeski Ron P.
Published: May 2009

The force-moment capabilities of branch-redundant planar-parallel manipulators (PPMs) are investigated. A previously developed explicit methodology for generating the force-moment capabilities of redundant PPMs is used on three different PPM architectures. The results for the 4-RRR, 4-RPR, 4-PRR layouts (where the underline denotes the actuated joint in each branch) are presented and discussed. For the revolute-actuated layouts, it was shown that the force-moment capabilities for the 4-RRR were in general better than those of the 4-RPR for the chosen manipulator parameters. The presented analysis is an effective tool for designing PPMs to determine the largest forces and moments that can be applied at any point within the workspace.
Task-Based Configuration Management for Modular Serial Robotic Manipulators
Authors: Rios Oziel , Krishnamoorthy Ganesh , Hulse Aaron , Koran Lucas , Gully Benjamin , Seepersad Carolyn Conner , Tesar Delbert
Published: May 2009

Modular robotic systems have become popular in recent years due to the ease of reconfigurability to satisfy varying task requirements. Due to the nonlinear nature of the actuator performance parameters, it is often difficult to map component specifications to the overall system performance making it cumbersome to use these parameters to design the system. Specifying system requirements based on task specifications, on the other hand, provides greater insight into how the system must perform in order to complete a given task and the resources required to achieve this performance. In this paper, we present a method for optimal design of modular robotic manipulators using a finite set of actuators to execute various tasks. Three different tasks — material removal, welding and a pick-and-place operation — which have different requirements in terms of the force, speed, precision and energy required to perform them, are considered. A set of five actuators is used to form different serial robotic manipulator configurations whose ability to accomplish the task is then evaluated using various performance metrics. A sequential filtering method is used to eliminate infeasible manipulator configurations and the remaining feasible set of manipulator configurations are then optimized using the weighted sum and compromise multiobjective optimization methods to determine a Pareto optimal manipulator configuration to accomplish each of the three tasks individually, in addition to a fourth manipulator configuration that is capable of accomplishing all the three tasks.
Simulation, Design, and Testing of a High Performance Multi-Axis Hexapod for Vibration Isolation
Authors: Jahn Bernie R.
Published: May 2009

This paper describes the simulation, design, and testing of a high-performance six degree-of-freedom hexapod for the purpose of isolating sensitive payloads from low-frequency vibrations. Design criteria required the hexapod to support a generic payload up to 500 lb with an isolation plunge frequency of approximately 1 Hz. Simulations were performed using Matlab in order to determine the optimum geometry of the base and platform structures in order to provide the best combination of translation-rotation uncoupling, frequency spread, plunge frequency, and jitter. Based on these simulation results, hexapod base and platform structures were designed and fabricated based on a 50 inch-diameter platform size. All of the accumulators and pneumatic hardware were embedded into the base structure to allow for a totally contained system. Modal testing of the hexapod was performed in order to verify the modes predicted by the model.
Numeric Synthesis of the Control Movement of Robotics With the Redundant Constraints and Drives
Authors: Gorobtsov Alexander
Published: May 2009

The robotics systems of arbitrary structures with closed loops, redundant constraints and drives are investigated. Propose the method of the transform redundant constraints for exclude static indefinite and provide predefines accuracy numeric solution. The method based on introduces some kinematics subchain at full kinematics chain of machine. Redundant constraints set finds by special assemble algorithms. Proposed theoretical method was incorporated at multibody dynamics simulation program FRUND. The paper presents the results computer simulation some types examples. The first types of examples are CLAWAR (walking machines). The problem of the control movement walking machine at statically unstable regimes is considering. The second type of examples is the vehicle steering and stability. The theoretical parameters of the stability walking machines and wheels car are compared.
Imbalance Detection and Health Monitoring From Gain Variations in an Adaptive Disturbance Rejection Controller
Authors: Barber Kelly , Flowers George T. , Matras Alex , Balas Mark , Fausz Jerry
Published: May 2009

Health monitoring is of critical importance in maintaining the integrity of high-speed rotating machinery. In this paper, a health monitoring strategy based upon the acquisition and analysis of vibration measurements is described and evaluated. A common technique in this regard is to track changes in the synchronous vibration due to imbalance. However, such an approach must consider the controller strategy used with the magnetic bearings. Herein, a simulation model is developed that consists of a flywheel system supported by magnetic bearings, which are controlled using an adaptive strategy that suppresses synchronous vibration. The interaction between the rotor vibration and the controller responses are evaluated in order to provide insight into indicators of crack initiation and growth. The results and conclusions are also validated using an experimental test rig. Some insights and guidelines as to appropriate strategies for crack detection in rotor systems interacting with active bearing controllers is presented and discussed.
Q2S2: Merging Qualitative Information in Sequential DOE
Authors: Rai Rahul , Campbell Matthew I.
Published: May 2009

Sequential sampling refers to a set of design of experiment (DOE) methods where the next sample point is determined by information from previous experiments. This paper introduces a qualitative and quantitative sequential sampling (Q2S2) technique, in which optimization and user knowledge is used to guide the efficient choice of sample points. This method combines information from multiple fidelity sources including computer simulation models of the product, first principals involved in design, and designer’s qualitative intuitions about the design. Both quantitative and qualitative information from different sources are merged together to arrive at a new sampling strategy. This is accomplished by introducing the concept of a confidence function, C, which is represented as a field that is a function of the decision variables, x, and the performance parameter, f. We compare the sampling plans generated by Q2S2 to previously known sample plans on five test functions using various metrics. In each case, the performance of Q2S2 is highly encouraging.
A Low Computational Cost Nonlinear Formulation for Multibody Railroad Vehicle Systems
Authors: Sanborn Graham G. , Heineman Jason R. , Shabana Ahmed A.
Published: May 2009

In this investigation, a multibody system formulation for the nonlinear dynamics of railroad vehicles is developed. This formulation, which permits developing simplified models for the forces acting on rail cars, allows the analysis of long trains at a low computational cost. In the dynamic models developed using the formulation proposed in this investigation, each rail car can be represented as a single rigid body. The configurations of the bodies in a train model are defined with respect to trajectory coordinate systems which follow a space curve whose geometry is defined at a preprocessing stage. In the formulation presented in this study, the number of degrees of freedom of an arbitrary body can be varied from one to six degrees of freedom. The principal degree of freedom of an arbitrary body is the arc length along the space curve. This degree of freedom defines the location of the origin and the orientation of the body trajectory coordinate system. The other five degrees of freedom define the location and orientation of the body with respect to the body trajectory coordinate system. The nonlinear equations of motion of the bodies in a train model are developed using the three-dimensional Newton-Euler equations. These equations are then expressed in terms of the trajectory coordinates and their derivatives. To this end, a velocity transformation is obtained by expressing the Cartesian and angular velocities of the bodies in terms of the time derivatives of the trajectory coordinates. Various force element models particular to rail cars are developed in this study. These forces include tractive effort, and air brake and dynamic brake forces, as well as a model of available wheel-rail adhesion. Additionally, various types of couplers are formulated as force elements, allowing the modeling of connections between cars. Resistance forces are also modeled in order to be able to simulate rolling, curve, and air resistance forces that may act on the cars during the train operations.
Developing Ontologies for Engineering Information Retrieval
Authors: Li Zhanjun , Raskin Victor , Ramani Karthik
Published: May 2009

When engineering content is created and applied during the product lifecycle, it is often stored and forgotten. Since search remains text-based, engineers do not have the means to harness and reuse past designs and experiences. On the other hand, current information retrieval approaches based on statistical methods and keyword matching are not directly applicable to the engineering domain. We propose a new computational framework that includes an ontological basis and algorithms to retrieve unstructured engineering documents while handling complex queries. The results from the preliminary test demonstrate that our method outperforms the traditional keyword-based search with respect to the standard information retrieval measurement.
Direct Pose Measurement: A Suitable Way to Increase the Accuracy of Parallel Robots?
Authors: Munzinger Christian , Kipfmu¨ller Martin
Published: May 2009

Parallel robots are showing a high potential for the application in machine tools requesting high stiffness and dynamics. Nevertheless, a broad use of parallel mechanisms in machine tools is nowadays avoided by the minor accuracy of parallel kinematic machines compared to conventional machine tool structures, which entails the need for complex calibration algorithms. In this paper, a strategy to avoid the calibration of parallel kinematic machines by rearranging the measurement system to the end effector is presented. Because this rearrangement entails a massive modification of the machine tools control circuit that causes stability problems, first tests of the concept have been carried out via simulation. The focus of these tests was to determine the necessary dynamic parameters of a suitable machine tool’s structure. The results of these tests are used to derive guidelines for the design of a machine tool with direct pose measurement. Finally, a design approach for a suitable machine tool is presented.
Control of First Order Systems With Bounded Input by Asymptotic Output Tracking With Fractional Regulators
Authors: Marti´nez Rube´n , Mazaira Israel , Feliu Vicente
Published: May 2009

In this paper, the control of first order systems by applying fractional regulators in the time domain with bounded input is presented. The design of the proposed fractional regulator, is based in the local asymptotic output tracking of linear systems with bounded control input by linear dynamic state feedback and the reduction of the system time response by the expansion of integer-order models to rational-order one.
Building Component Based Software Connectors for Communication Middleware in Distributed Embedded Systems
Authors: Schreiner Dietmar , Go¨schka Karl M.
Published: May 2009

Interaction in distributed component based software-architectures can become a rather complex and error prone issue. As it is good practice to keep application concerns separated from infrastructural ones, component based applications typically rely on communication middleware to cope with matters of distribution and heterogeneity. Unfortunately, generic middleware tends to be monolithic, heavyweight software, which is unacceptable in resource constrained embedded systems. Communication middleware for distributed embedded systems has to be custom tailored to the application’s interaction needs and therefore shall be as lightweight as possible. By applying the component paradigm to the communication middleware, a practical methodology can be defined, that allows the middleware’s automatic generation from the application’s architectural models and structural designs of explicit component connectors with a well defined set of prefabricated basic building blocks—so called communication primitives. This paper contributes by specifying the most common structural designs for explicit connectors within the automotive domain and thereby, in addition identifies a set of classes of automotive communication primitives. Thus this paper provides the sound foundation for automatic, model driven middleware synthesis by specifying all necessary basic modules.
Practical Methods for Managing the Gear Whine Phenomena
Authors: Abe Takeshi , Cheng Yuping , Nowaczyk Ken , Wilson Brian K.
Published: May 2009

Unprecedented competition among the worldwide automotive manufacturers has benefited the consumer, resulting in higher levels of overall quality while simultaneously reducing the time-to-market for new models. One subjective differentiator of automotive quality is the noise and vibration performance, as evident by the quieter interiors even in vehicles not typically associated with the luxury banner, such a large trucks. In essence, passenger compartments devoid of objectionable road and wind noise have become a fundamental customer requirement expected in all vehicles regardless of cost, thereby reducing the broadband masking content of the interior. This reduction of masking has the potential to make tonal noise more prominent and annoying, by increasing the tone-to-noise ratio, and as result, the perception of quality may suffer. Gear whine is one such tonal noise phenomena that must be diligently managed by automotive engineers in order to avoid objectionable passenger compartment noise. This can be quite challenging, since many gear design features implemented for increased durability are often counter productive for noise. Sources of gear whine include powertrain components such as automatic and manuals transmissions, axles, transfer cases, power-take of units, engine accessory drives, and an assortment of other potential noise makers. This paper will attempt a technology review of various practical methods for managing the gear whine phenomena, including the use of Quality Function Deployment charts, dynamic transmission error with parametric gear models, and response surface modeling for gear design optimization.
A Grey Sliding Mode Controller Design for Antilock Braking System
Authors: Oniz Yesim , Kayacan Erdal , Kaynak Okyay
Published: May 2009

The main control objective of an Antilock Braking System (ABS) is to increase the tractive forces between wheel and road surface by keeping the wheel slip at the peak value of μ – λ curve. Conventionally, it is assumed that optimal wheel slip is constant. In this paper, a grey sliding mode controller is proposed to regulate optimal wheel slip depending on the vehicle forward velocity. ABS exhibits strongly nonlinear and uncertain characteristics. To overcome these difficulties, robust control methods should be employed. The concept of grey system theory, which has a certain prediction capability, offers an alternative approach to conventional control methods. The proposed controller anticipates the upcoming values of wheel slip and optimal wheel slip, and takes the necessary action to keep wheel slip at the desired value. The control algorithm is applied to a quarter vehicle model, and it is verified through simulations indicating fast convergence and good performance of the designed controller.
Motion Planning and Control of Artificial Muscle Actuated Underwater Vehicle Using Nonlinear Neural Oscillator
Authors: Lee Joon Soo , Yim Woosoon , Kim Kwang J.
Published: May 2009

In this paper, we introduce the motion planning and control strategy for the underwater vehicle actuated by a soft artificial muscle actuator. The artificial muscle used for this underwater application is an Ionic Polymer Metal Composite (IPMC) which can generate bending motion in aquatic environments. In this research, the double ring structured nonlinear neural oscillator is proposed for the undulatory motion in the actuator. The overall dynamic model of the flexible IPMC actuator including its fluid interaction terms is used for the motion planning and open-loop controller design. The IPMC used in this study is a patterned or segmented type where the electrode surface of the actuator is encoded such that each segment can be controlled independently for effectively generating an undulatory motion in the water. Computer simulations show that the proposed neural oscillator based controller can be effectively used for the underwater locomotion applications, and can be extended to the closed-loop controller where the precise maneuver is needed in the unstructured aquatic environments.
Joint Rotation Space and Mobility of Linkages
Authors: Ting Kwun-Lon
Published: May 2009

The paper presents a general concept regarding the joint rotation space (JRS) of single loop planar and spherical N-bar linkages as well as its significance and applicability in multiple loop and spatial linkages. A JRS refers to the input domain of a linkage. The paper first discusses and classifies the JRS types of single loop five-bar linkages based on the types of the JRS boundary. The concept of sheets and pages of JRS is then introduced as an aid to understand the mobility of linkages. A sheet refers to the JRS of a linkage branch (or circuit). A JRS sheet may have one or more pages and each page refers to an uncertainty singularity free JRS. The concept is then generalized to any single loop planar and spherical N-bar linkages (N ≥ 3). The paper offers geometric insights to the input domain of a linkage and establishes a one-to-one correspondence between the input domain and the linkage configurations. The applications to the mobility identification of complex linkages are discussed and demonstrated with geared five-bar linkages, Stephenson six-bar linkages, as well as spatial RCRCR mechanisms. The paper presents a useful model explaining the fundamental principle regarding the formation of branches and sub-branches in Stephenson six-bar linkages as well as some other multiloop and spatial linkages. The Mobility similarity between multiloop linkages and spatial linkages is also highlighted.
Experimental and Numerical Simulations of Percussive Diagnosis of Lung Pathologies
Authors: Acikgoz Serhan , Royston Thomas J. , Mansy Hansen A. , Sandler Richard H.
Published: May 2009

A mechanical phantom model was built to simulate percussive techniques for diagnosing pneumothorax (PTX) and hydrothorax (HTX) (collapsed lung with air or water in the pleural space, respectively). The model was built with materials that have similar acoustic properties to that of human parenchyma, soft tissue and ribs. A bladder was embedded into the parenchyma-mimicking foam to simulate PTX or HTX. Experimental frequency response measurements were taken on the mechanical phantom model for the simulated pathologies and the healthy case with percussive excitation and noninvasive response measurements at the soft tissue surface. To aid in understanding experimental measurements, a finite element model of the experimental setup was constructed in ANSYS and used to simulate these same cases. Normal velocity amplitudes over the soft tissue surface measured from the experimental setup and calculated via the finite element model were analyzed in the frequency domain to identify any patterns or signatures that could be exploited for diagnosis. Experiment and numerical studies agree in identifying the key features of the PTX condition versus the healthy case, but differ somewhat on how HTX can be distinguished from PTX and the healthy case. Reasons for this discrepancy are discussed. With some improvements, these computational and experimental phantom models may aid in the development of improved noninvasive acoustic techniques for identifying these and other life-threatening conditions.
Kinematic Design of Mechanisms for the Control of an Oscillating Wing
Authors: Allen Demers Louis-Alexis , Gosselin Cle´ment
Published: May 2009

This work is part of a project which aims at the development of underwater generators using oscillating wings. One of the important challenges in the design of a system collecting the kinetic energy of a fluid is the transformation of this energy into electric power [1]. Since it is not possible to pass directly from the movement of a fluid to electric power, it is necessary to conceive an intermediate mechanical system. Its function is to convert the kinetic energy of the fluid into kinetic energy of a mechanism capable of converting kinetic energy into electric power. In this work, the mechanical system also has an additional function, i.e., to guide the orientation of the blades (wings) throughout the cycle of movement in order to maximize the efficiency.