bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Approach to Interactive Grasping Simulation of Product Concepts in a Virtual Reality Environment
Authors: Rusa´k Zolta´n , Antonya Csaba , van der Vegte Wilfred , Horva´th Imre , Varga Edit
Published: May 2009

Customer evaluation of concepts plays an important role in the design of handheld devices, such as bottles of douche gels and shampoos, where the phenomenon of grasping needs to be evaluated. In these applications important information on the aspects of ergonomics and user behaviors could be gathered from computer simulation. It is our ultimate goal to develop an environment in which users and designers can freely interact with product concepts. In our approach to grasping simulation there is no tactile feedback and we do not measure the exerted grasping forces. There is no wiring of the human hand, and the users are not limited in their movements. We measure the motion of the human hand, compute the grasping forces based on anthropometric data, and simulate the reaction of product concepts in a physically based virtual reality environment. Our contribution consists of: (i) a method, which takes into account the anatomy of the human hand in order to determine the maximum grasping forces, and (ii) an approach which enables to control the grasping forces based on (a) the penetration of the virtual human hand into the virtual model of product concept (b) the posture of the grasping, and (c) the angles of the joints. The paper reports on the framework of our approach and presents an application.
Active Control of Radial Rotor Vibration in Cage Induction Electrical Machines by a Built-in Force Actuator
Authors: Laiho Antti , Burakov Andrej , Tammi Kari , Zenger Kai , Arkkio Antero
Published: May 2009

In this paper active control of radial rotor vibrations in electrical machines is studied. We consider attenuation of rotation speed harmonic vibration components by using a built-in force actuator. The action of the actuator is based on the electromechanical interaction between the rotor and the stator of the machine. Actuator is given a low-order linear state-space model which is identified by time-stepping finite element simulations. An adaptive control strategy is applied and numerical simulation results with test machine parameters are presented.
Elastic Boundary Layers in Two-Dimensional Isotropic Lattices
Authors: Phani A. Srikantha , Fleck Norman A.
Published: May 2009

The phenomenon of elastic boundary layers under quasistatic loading is investigated using the Floquet-Bloch formalism for two-dimensional, isotropic, periodic lattices. The elastic boundary layer is a region of localised elastic deformation, confined to the free-edge of a lattice. Boundary layer phenomena in three isotropic lattice topologies are investigated: the semi-regular Kagome lattice, the regular hexagonal lattice and the regular fully-triangulated lattice. The boundary layer depth is on the order of the strut length for the hexagonal and the fully-triangulated lattices. For the Kagome lattice, the depth of boundary layer scales inversely with the relative density. Thus, the boundary layer in a Kagome lattice of low relative density spans many cells.
New Gear Manufacturing Technologies in the Automotive Field of Transmissions, Axle Drives and Transfer Cases
Authors: Jeitler Bernd , Hinteregger Christian , Leitner Heinz
Published: May 2009

Thanks to its innovative products in the field of all-wheel drives, Magna Powertrain (MPT) has positioned itself in manufacturing high-performance All wheel drive gearboxes in the worldwide market very well. The continuity of the overall development process from manufacturing via assembly to comprehensive performance checks with integration in the vehicle is decisive for MPT’s system competence. In order to meet the customers’ requirements even in future, it is, in the long run, not only necessary to provide innovations that are relevant to the function. It also is absolutely required to enable optimizations based on innovative manufacturing concepts and methods will be done by innovative material selection, new manufacturing process chains or in their combination. Today the degree of optimization of machining, which is used for manufacturing gearing, is already very high. Therefore, advantages relating to manufacturing technology can only be achieved by completely changing the manufacturing concept. It is a matter of massive forming processes, which are particularly suitable as pre-processes or finishing processes for such gearing. Such terms as “Net shape” or “Near net shape” have been already integrated in literature for describing these manufacturing processes. Hot forming, semi-hot-forming or cold forming processes or their combination can be used depending on the geometrical requirements to achieve these near-net shape- or net shape condition. For slightly loaded, slow-rolling-off gear pairs, this process already is state of the art in many cases. In the field of highly loaded fast-rolling-off-involute cylindrical gears, we are entering new territory, no matter whether it is a question of all-wheel drive gear boxes, automatic or manual transmissions or of applications in the engine. The requirements placed on fatigue strength and gearing noise are correspondingly high for such gearing. This is a particular challenge both for innovative manufacturing technology and the design and test programme. In this paper you were shown about the status of current predevelopment programs regarding manufacturing of toothing for high speed gears.
A Dummy for Reproducing the Human Whole Body Vibration
Authors: Mastinu Giampiero , Gobbi Massimiliano , Pennati Mario
Published: May 2009

The paper presents an innovative dummy conceived to provide an effective tool for an objective vehicle ride comfort evaluation. The first part of the research includes experimental tests on instrumented seats for evaluating the vertical (cushion) and longitudinal (backrest) acceleration between the vehicle seat and the seated human subject. Experiments have been performed by using a vibrating table fitted with a vehicle seat and by seating directly the subjects on vehicles (cars and light trucks) while running on a test track. The test track includes uneven road and different obstacles. Human subjects have been chosen in order to obtain a high variability in the anthropometric features (height, weight, gender, age). Several test have been also performed with the same subject submitted to the same excitation in order to investigate the inter-subject variability and the intra-subject variability. During the study different seats have been compared. From the acquired data, a mathematical model of the system, human subject + seat has been derived and numerically validated by minimizing the error between the measured and the computed accelerations. The corresponding mechanical device has been built, the MaRiCO dummy. The device is fully adjustable in order to simulate the vibrational behaviour of different human subjects. Particular attention has been devoted to the construction of the springs and of the magnetic damper to reduce as much as possible the friction between the moving components. The dummy rests on the seat by means of special elements that, thanks to their compliance and conformation, act as the tight and the back of human beings. An experimental validation of the dummy has been performed. The device, opportunely tuned and seated with the same posture of the corresponding human subject is able to reproduce the acceleration between the subject and both the cushion and the backrest.
Harmonic Balancing of Planar Machinery by Arbitrarily Placed Counterweighing Shafts
Authors: Innocenti Carlo
Published: May 2009

The paper proposes a new method to neutralize the shaking force and shaking moment exerted on its supporting structure by a one-degree-of-freedom machine whose non-stationary parts move parallel to the same plane. Differently from the well-known technique that takes advantage of two counterweighing shafts for each of the harmonic components of the frame excitation that has to be counteracted, the proposed method requires three shafts per harmonic component. This seemingly additional complexity is offset by the complete freedom of selection of the shaft axis positions, a feature not enjoyed by the classical two-shaft device. An example shows application of the proposed method to a four-cylinder in-line engine.
A Kinematic Study of Human Torso Motion
Authors: Simonidis Christian , Stelzner Gu¨nther , Seemann Wolfgang
Published: May 2009

This paper illustrates a kinematic study of human torso motion in order to design and transfer human-like motion on humanoid robots. The realization is done using motion capture data and an optimization based inverse kinematic approach for mapping motion data to skeleton models with the main focus on reproducing realistic torso motion. The kinematic model is based on a multiybody approach using relative coordinates. According to the difficulty of marker based motion reconstruction of human torso movements a detailed multibody model of the spine with a coupling structure between vertebrae based on medical data is introduced. Then, a new formulation describing the kinematic constraints between pelvis and shoulder girdle is presented in order to simplify modeling effort while maintaining natural motion of the torso. Results are compared for key movements with common models. The developed models will be used for design application in the Collaborative Research Center 588 “Humanoid Robots - Learning and Cooperating Multimodal Robots”.
Suppression of Vibration by Using Antiresonance Point of a Dynamic Vibration Absorber
Authors: Okaguchi Hidetoshi , Yabuno Hiroshi
Published: May 2009

The conventional passive dynamic absorber reduces the amplitude of the main system when the natural frequency of the absorber corresponds to the excitation frequency. The dynamic absorber produces two resonance peak. In this paper, we propose a control method of the semi-active dynamic absorber to reduce the amplitude of the main system to zero over the wide range of excitation frequency. The proposed controller has the system of real time estimation of excitation frequency by applying adaptive filter. When the excitation frequency varies, the frequency is estimated by the controller in real time and control signal is generated according to the estimated frequency. As a result, the natural frequency of the absorber is changed in real time and the amplitude of the main system is kept to zero over the wide range of excitation frequency. The performance of the proposed control method is experimentally discussed.
A Simple Approach to Kinematic Inversion of Redundant Mechanisms
Authors: Fumagalli Alessandro , Gaias Gabriella , Masarati Pierangelo
Published: May 2009

This work addresses the problem of kinematic inversion of complex redundant mechanisms. The inverse problem for redundant mechanisms is known to be ill-posed. Using the multibody formalism and the capability to automatically write the equations of motion of mechanisms provided by general multibody software, a simple algorithm is proposed for the solution of the inverse kinematics problem for redundant robotic systems. The algorithm, in its basic form, is equivalent to the classical Moore-Penrose pseudo-inverse applied to the Jacobian matrix of the constraints. The inverse solution is found in a least squares sense: among the infinite admissible solutions, the one with minimum norm is chosen. Little extra effort allows the computation of optimized inverse kinematics. In this case, the solution is found in a weighted least squares sense. Weights can be automatically chosen by an optimization algorithm in order to minimize a given cost function, or assigned by the user based on engineering judgment. Among the advantages of the proposed approach, it is worth mentioning its simplicity and the possibility to be used within generic multibody software with very limited effort.
Dynamic Signal Interpretation of Rotary Machines Using Adaptive Order Tracking
Authors: Pan Min-Chun , Wu Cheng-Xue
Published: May 2009

This paper proposes and implements an adaptive Vold-Kalman filtering order tracking (VKF_OT) approach to overcome the deficiencies of the original VKF_OT scheme for condition monitoring and diagnosis of rotary machinery. This article comprises theoretical derivation, numerical implementation and experimental validation. Comparisons of the adaptive scheme to the original are accomplished through processing a synthetic signal composed of close order components. Parameters such as the weighting factor and the correlation matrix of process noise, which influences tracking performance, are investigated in the study. The adaptive OT scheme based on the Kalman filter can be computed on-line and implemented as a real-time processing application. This paper also illustrates experimental validation through the separation of two close orders arising from a transmission test bench.
Nonlinear Model Based Estimation of Rigid-Body Motion Via an Indirect Measurement of an Elastic Appendage
Authors: Mor M. , Wolf A. , Gottlieb O.
Published: May 2009

In this paper we develop and implement a nonlinear model based procedure for estimation of rigid body motion via an indirect measurement of an elastic appendage. We demonstrate the procedure by motion analysis of a compound planar pendulum from indirect optoelectronic measurements of markers attached to an elastic appendage that is restrained to slide along the rigid-body length. We implement a Lagrangian approach to derive a theoretical nonlinear model that consistently incorporates the generalized forces acting on the system. Identification of the governing linear and nonlinear system parameters is obtained by analysis of frequency and damping backbone curves obtained from controlled experiments of the decoupled system elements. Comparison of an independently measured rotation angle to that obtained by the model-based estimation procedure enables evaluation of the procedure accuracy and its advantages over standard noninvasive methods.
Development of a Production Information Management System to Support Environmental CSR Activities for Process Production
Authors: Shimizu Takafumi , Kanai Satoshi , Ichinohe Masayuki , Ohashi Toshijiro , Nakagawa Yasuo
Published: May 2009

Recently, awareness of Corporate Social Responsibility (CSR) has been raised and various environmental regulations have spread in many countries. Under this situation, manufacturers of process production, production information management systems are required that can archive and retrieve data not only of final products and raw materials but of chemical substances contained, intermediate products and wastes generated, and energy consumption during the production. However, management systems and product models currently used for assembly production do not fit the above requirement. To solve the problem, first, an object-oriented process-product model was designed which can represent these data and can be easily implemented on commercial ORDBMS. Second, traceability functions of explosion and implosion covering chemical substances, intermediate products, wastes and energy were developed on the ORDBMS. Third, a generic environmental law model was designed which can represent restrictions of various environmental regulations in a uniform way. Finally, a conformance checking function for environmental regulations was developed by combining the generic environmental law model with the process-product model. The effectiveness of the models and functions was verified by applying them to full-scale production data of functional polymer films and checking its conformance to RoHS and EuP directives.
Numerical Simulation of Gas Flow in a Square Cyclone Separator With Double Inlets
Authors: Xiong Bin , Lu Xiaofeng , Amano R. S.
Published: May 2009

This paper presents a numerical study of gas flow in a square cyclone separator with a double inlet. The turbulence of gas flow is computed by the use of the Reynolds stress model. The distribution of the flow field and pressure drop under different constructional details, which include changes of the shape, size and arrangement of the vortex finder are obtained. The computed results in the distributions of pressure in different sections are verified by comparison with those measured. We found that the center of the flow field is nearly on the geometric center of the cyclone. The flow fields show a feature of Rankine eddy, i.e., a strongly swirling region in the central part and a pseudo-free eddy region of weak swirling intensity near the cyclone wall. Local vortex exists at the corners where the flow changes their direction sharply, but it is less chaotic than in the general square cyclone with a single inlet. The flow field away from the outlet of the vortex finder is different from the Rankine eddy. The pressure-drop increases rapidly with the increase of the inlet velocity, and the pressure-drop increases with the decrease of the diameter of vortex finder and the increase of length of the vortex finder. The calculat ed results of this paper provide some guidance for the optimization of the square cyclone separator structure.
Modeling and Simulation of Woven Fabrics and Woven Fiber-Reinforced Composites Based on a Nonlinear Fiber Model
Authors: Ma Zheng-Dong , Jiang Dongying , Liu Yuanyuan
Published: May 2009

A three-dimensional nonlinear thread formulation developed by the first two authors [1] has been extended in this paper for modeling and simulation of woven fabrics and fiber-reinforced composites of various configurations under arbitrary large deformation. The resultant model accounts for extensibility of the woven fibers in the composite, geometry nonlinearity, tension variation along the fiber, and other nonlinear effects due to the woven composition and large deformation. The new modeling effort includes the development of a contact model for simulating the contact between fibers, which can be used to predict high-fidelity behavior of woven fibers in the composite and their interactions. Matrix model is also added into the composite for studying the coupling between woven fibers and matrix material such as resin. The incremental form of original nonlinear equation is discretized using a finite element method with an iteration scheme. Two numerical examples are given to demonstrate the effectiveness of the proposed modeling technique.
Investigation of the Quality of Shape Definition by Hand Motions
Authors: Varga Edit , Horva´th Imre , Rusa´k Zolta´n
Published: May 2009

In preceding research, the concept of the Hand Motion Language (HML) was developed as a novel and intuitive interface for Computer Aided Conceptual Design (CACD) systems. Also, a pilot implementation of the HML interpreter was developed and tested. Current research focuses on the applicability of HML in real-life situations. Firstly, this paper reports on the connection of the HML to the Vague Discrete Interval Modeler (VDIM) as an input interface. Together with the HML interpreter, it serves as a testing environment. Secondly, the paper concentrates on the design and evaluation of an experiment which was done to study the quality of shape definition by hand motions. Three quality measures were established: (i) fidelity of the generated surfaces, (ii) accuracy of the surface manipulation functions, and (iii) difficulty of modeling. Fidelity is the degree to which the representation of a shape is similar to an ideal shape. Accuracy is defined as the degree of conformity of an indicated value, such as width or angle, to an ideal value. With regards to complexity, it is interesting for us how the number of geometric HML words relates to the number of manipulative HML words that has to be issued to model a given shape. A pilot study was designed and performed to gain insight into the problems when generating surfaces by hand motions. The task given to the users was completed within a few steps; however, the quality of the surfaces has to be improved.
System Identification Using Fractional Models: State of the Art
Authors: Malti Rachid , Victor Ste´phane , Nicolas Olivier , Oustaloup Alain
Published: May 2009

This paper presents a state of the art of actual achievements in time-domain system identification using fractional models. It starts with some general aspects on time and frequency-domain representations, time-domain simulation, and stability of fractional models. Then, an overview on system identification methods using fractional models is presented. Both equation-error and output-error-based models are detailed. In the former models, prior knowledge is generally used to fix differentiation orders; model coefficients are estimated using least squares. The latter models allow simultaneous estimation of model’s coefficients and differentiation orders, using non linear programming. A real thermal example is identified using a fractional model and compared to a rational one.
Fully Comprehensive Geometrically Non-Linear Analysis of Anisotropic Composite Beam Systems
Authors: Pollayi Hemaraju , Harursampath Dineshkumar
Published: May 2009

This paper describes a comprehensive approach to analyse anisotropic composite beams. Based on geometrically non-linear elasticity theory, the non-linear 3-D beam problem splits into either a linear or non-linear 2-D analysis of the beam cross-section and a non-linear 1-D analysis along the beam reference line. Usually cross-sectional analyses are linear, but there are a few exceptions, like the “trapeze effect” and “Brazier effect”. The two sub-tasks of this work (viz. non-linear analysis of the beam cross-section and non-linear beam analysis) are to be accomplished on a single platform using object-oriented framework. First, we perform a non-linear numerical cross-sectional analysis, based on the Variational-Asymptotic Method (VAM). It is capable of treating cross-sections of arbitrary geometry and generally anisotropic material. Second, we formulate the comprehensively non-linear 1-D governing equations along the beam reference line using the mixed variational method and the expressions for non-linear stiffness matrix. The dynamic response of non-linear, flexible multibody systems is thus simulated within the framework of energy-preserving and energy-decaying time integration schemes that provide unconditional stability for non-linear systems. Finally, local 3-D stress, strain and displacement fields for representative sections in the component beams are recovered, based on the stress resultants from a 1-D global beam analysis. Results from this analysis are compared with those available in the literature, both theoretical and experimental, and focus on the behavior of multi-body systems involving members with elastic couplings.
Towards a Generic “Single-Path Programming” Solution With Reduced Power Consumption
Authors: Gendy Ayman K. , Pont Michael J.
Published: May 2009

As embedded designs become more widespread and complex they tend to use more modern processors. Such processors will often include features (such as pipelines, caches, and branch predictors) which help to improve performance. While such performance improvements are welcome, they come at the price of predictability. More specifically, the use of advanced processor hardware makes it difficult to predict the worst-case execution time (WCET) of tasks. As part of an effort to address these problems, Puschner and Burns (Proc. 7th IEEE International Workshop on Object-Oriented Real-Time Dependable Systems, Jan. 2002) proposed the “single path programming paradigm”. As its name implies program code written according to this paradigm has only one execution path: this helps to ensure a constant execution time. Yet there are two problems with the techniques described by Puschner and Burns: (i) they are applicable only to hardware which supports “conditional move” or similar instructions; (ii) their balancing approach increases power consumption. In the present paper, we begin to address both of these problems with a set of novel code-balancing techniques. The effectiveness of these new techniques is explored by means of an empirical study.
Endoscope Geometrical Analysis and Kinematic Control
Authors: Lipkin Harvey , Munnae Jomkwun , McMurray Gary , Zhou Debao , Daley Wayne
Published: May 2009

Endoscopes are used in medical practice to effect minimally invasive diagnostics and treatments through a natural or surgical orifice. The endoscope is a snakelike device with a two degree-of-freedom articulated tip that bends in any direction using internal cables actuated by knobs. In this paper we use a serial robot model of the tip to show that the tip motions are not decoupled with respect to the knob inputs nor do they have constant gains. Further in a geometrical analysis it is shown that the articulated tip always lies along a circle. A tip kinematic control strategy is developed based on small motions that is able to decouple the output motions from the input motions and provide a constant gain functions. This allows the surgeon to control the endoscope in an intuitive and efficient manner.
Immersive Product Configurator for Conceptual Design
Authors: Zhang Ruqin , Noon Christian , Winer Eliot , Oliver James H. , Gilmore Brian , Duncan Jerry
Published: May 2009

Currently, new product concepts are evaluated by developing detailed virtual part and assembly models with traditional Computer Aided Design (CAD) tools followed by appropriate analyses (e.g., finite element analysis, computational fluid dynamics, etc.). The creation of these models and analyses are tremendously time consuming. If a number of different conceptual configurations have been determined, it may not be possible to model and analyze each of them. Thus, promising concepts might be eliminated based solely on insufficient time to assess them. In addition, the virtual models and analyses performed are usually of much higher detail and accuracy than what is needed for such early assessment. By eliminating the time-consuming complexity of a CAD environment and incorporating qualitative assessment tools, engineers could spend more time evaluating additional concepts, which were previously abandoned due to time constraints. In this paper, a software framework, the Advanced Systems Design Suite (ASDS), for creating and evaluating conceptual design configurations in an immersive virtual reality environment is presented. The ASDS allows design concepts to be quickly modeled, analyzed, and visualized. It incorporates a PC user interface with an immersive virtual reality environment to ease the creation and assessment of conceptual design prototypes. The development of the modeling and assessment tools are presented along with a test case to demonstrate the usability and effectiveness of the framework.
μ-Synthesis Control of Systems With Unknown Hysteresis Nonlinearity and Parametric Uncertainties
Authors: Bashash Saeid , Ayalew Beshah , Jalili Nader
Published: May 2009

This paper deals with μ-synthesis control approaches for a class of uncertain dynamic systems with unknown comple multi-loop hysteresis nonlinearity. By decoupling the hysteresis from the system dynamics, an uncertain linear dynamic system subjected to a static hysteretic input is achieved. A bound of uncertainty for the parameters of the dynamic system is considered and the hysteresis is reduced to a line with a known slope plus a varying function representing the difference of the approximate line and the hysteresis response. For the described uncertain system, μ-synthesis method is used to achieve both stabilization and tracking performance within a desired precision and bandwidth. Simulation performed on a perturbed nonlinear plant demonstrate the effectiveness of the approach when compared to other methods.
Cost-Benefit Quantification of ISHM in Aerospace Systems
Authors: Hoyle Christopher , Mehr Alexander F. , Tumer Irem Y. , Chen Wei
Published: May 2009

Integrated Systems Health Management (ISHM) is an evolving technology used to detect, assess, and isolate faults in complex aerospace systems to improve safety. At the conceptual design level, system-level engineers must make decisions regarding the inclusion of ISHM and the extent and type of the sensing technologies used in various subsystems. In this paper, we propose a Cost-Benefit Analysis approach to initiate the ISHM design process. The key to this analysis is the formulation of an objective function that explicitly quantifies the cost-benefit factors involved with using ISHM technology in various subsystems. Ultimately, to determine the best ISHM system configuration, an objective is formulated, referred to as Profit, which is expressed as the product of system Availability (A) and Revenue per unit Availability (R), minus the sum of Cost of Detection (CD) and Cost of Risk (CR). Cost of Detection includes the cost of periodic inspection/maintenance and the cost of ISHM; Cost of Risk quantifies risk in financial terms as a function of the consequential cost of a fault and the probabilities of occurrence and detection. Increasing the ISHM footprint will generally lower Cost of Risk while raising Cost of Detection, while Availability will increase or decrease based upon the balance of the reliability and detectability of the sensors added, versus their ability to reduce total maintenance time. The analysis is conducted at the system functional level, with ISHM allocated to functional blocks in the optimization analysis. The proposed method is demonstrated using a simplified aerospace system design problem resulting in a configuration of sensors which optimizes the cost-benefit of the ISHM system for the given input parameters. In this problem, profit was increased by 11%, inspection interval increased by a factor of 1.5, and cost of risk reduced by a factor of 2.4 over a system with no ISHM.
Robustness and Controllability Analysis for Autonomous Navigation of Two-Wheeled Mobile Robots
Authors: Salerno Alessio , Angeles Jorge
Published: May 2009

This work deals with the robustness and controllability analysis for autonomous navigation of two-wheeled mobile robots. The analysis of controllability of the systems at hand is conducted using both the Kalman rank condition for controllability and the Lie Algebra rank condition. We show that the robots targeted in this work can be controlled using a model for autonomous navigation by means of their dynamics model: kinematics will not be sufficient to completely control these underactuated systems. After having proven that these autonomous robots are small-time locally controllable from every equilibrium point and locally accessible from the remaining points, the uncertainty is modeled resorting to a multiplicative approach. The dynamics response of these robots is analyzed in the frequency domain. Upper bounds for the complex uncertainty are established.
Fractional Dynamics in Mechanical Manipulation
Authors: Lima Miguel F. M. , Machado J. A. Tenreiro , Criso´stomo Manuel
Published: May 2009

This paper analyzes the signals captured during the movement of a mechanical manipulator carrying a liquid container. In order to study the signals an experimental setup is implemented. The system acquires data from the sensors, in real time, and, in a second phase, processes them through an analysis package. The analysis package runs off-line and handles the recorded data. The results show that the Fourier spectrum of several signals presents a fractional behavior. The experimental study provides useful information that can assist in the design of a control system to be used in reducing or eliminating the effect of vibrations.
Mechanical Domain Parametric Amplification
Authors: Rhoads Jeffrey F. , Miller Nicholas J. , Shaw Steven W. , Feeny Brian F.
Published: May 2009

Though utilized for more than fifty years in a variety of power and communication systems, parametric amplification, the process of amplifying a harmonic signal with a parametric pump, has received very little attention in the mechanical engineering community. In fact, only within the past fifteen to twenty years has the technique been implemented in micromechanical systems as a means of amplifying the output of resonant micro-transducers. While the vast potential of parametric amplification has been demonstrated, to date, in a number of micro- and nano-mechanical systems (as well as a number electrical systems), few, if any, macroscale mechanical amplifiers have been reported. Given that these amplifiers are easily realizable using larger-scale mechanical systems, the present work seeks to address this void by examining a simple, representative example: a cantilevered beam with longitudinal and transverse base excitations. The work begins with the systematic formulation of a representative system model, which is used to derive a number of pertinent metrics. A series of experimental results, which validate the work’s analytical findings, are subsequently examined, and the work concludes with a brief look at some plausible applications of parametric amplification in macroscale mechanical systems.
Autonomous Helicopter for Surveillance and Security
Authors: Zingaretti P. , Mancini A. , Frontoni E. , Monteriu` A. , Longhi S.
Published: May 2009

Unmanned Aerial Vehicles represent today an advanced and complex robotics platform for novel tasks. For example, UAVs can be used in applications for traffic monitoring and surveillance, emergency services assistance, photogrammetry and surveying. Generally, an UAV must be fully autonomous; autonomy is accomplished by a complex interconnection of systems related to a wide range of topics, e.g., flight low level control, navigation and task-based planning, elaboration of sensor signals, software architecture for reactive behaviours, communication. Today the challenge is the ability to insert UAVs in a cooperative network based on autonomous agents as UAV, UGV (Unmanned Ground Vehicle) to accomplish a specific task a priori defined. In this paper we introduce a prototype of autonomous aerial vehicle, the Helibot helicopter, specifically designed for applications as surveillance and security.
Optimal Reduction Ratio Selection for the Driving System of a Novel High-Speed Parallel Manipulator
Authors: Zhang Xianmin , Yuan Jianfeng
Published: May 2009

The reduction ratio of the driving system plays a very important role in the accelerating and decelerating capacity for a parallel manipulator. In this paper, the virtual work principle was employed to develop the inverse dynamics model of a novel high-speed parallel manipulator. A new S-curve speed profile was introduced and adopted to plan the trajectory of the end-effecter of the manipulator in the operation space. Aiming at the minimal operation time, a reduction ratio optimal selection method of the driving system was presented, which can make full use of the advantages of the AC servomotor and consequently reduce the cost of the manipulator.
Reduced-Order Modeling of Two-Sided Frictional Interfaces
Authors: Miller Jason D. , Quinn D. Dane
Published: May 2009

We consider a model describing the behavior of a two-sided interface allowing for both elasticity and microslip of the joint. A reduced-order approximation of this system is developed based on a decomposition of the original model into an elastic chain and a dissipative component equivalent to a series-series Iwan chain. The Iwan chain is then solved using a quasi-static complementarity formulation while the order of the elastic chain is reduced using modal analysis. The computational efficiency of the resulting reduced-order model is significantly increased, while the overall response of the interface to realistic forcing conditions is maintained.
GPU-Based Real-Time Occlusion in a CAVE-Based Augmented Reality Environment
Authors: Lu Yuzhu , Smith Shana
Published: May 2009

In this paper, we present a prototype system which makes use of the characterisitcs of CAVE-based virtual reality to enhance immersion in an augmented-reality environment. The system integrates virtual objects into a real scene captured by a set of stereo remote cameras. We also developed a GPU-based method for computing occlusion between real and virtual objects, in real time. The method uses information from the captured stereo images to determine depth of objects in the real scene. Results and performance comparisons show that the GPU-based method is much faster than prior CPU-based methods.
Discrete Mechanical Systems: Projective Constraint Violation Stabilization Method for Numerical Forward Dynamics on Manifolds
Authors: Terze Zdravko , Naudet Joris
Published: May 2009

During numerical forward dynamics of discrete mechanical systems with constraints, a numerical violation of system kinematical constraints is the basic source of time-integration errors and frequent difficulty that analyst has to cope with. The stabilized time-integration procedure, whose stabilization step is based on projection of the integration results to the underlying constraint manifold via post-integration correction of the selected coordinates, is proposed in the paper. After discussing optimization of the partitioning algorithm, the geometric and stabilization issues of the method are addressed and it is shown that the projective stabilization algorithm can be applied for numerical stabilization of holonomic and non-holonomic constraints in Pfaffian and general form. As a continuation of the previous work, a further elaboration of the projective stabilization method applied on non-holonomic discrete mechanical systems is reported in the paper and numerical example is provided.
Ferromagnetic Shape Memory Thin Film In-Plane Actuators: Assessment of Mechanical Output
Authors: Stoilov Vesselin
Published: May 2009

Ferromagnetic shape memory alloy micro actuators and motors are promising for applications in various servo control systems, with the potential to provide ultra(sub-nano)-precision positioning and compensation. This article shows that in an in-plane configuration, thin film ferromagnetic shape memory actuators open the possibility to reach more powerful actuators keeping the same geometric dimensions by simply stacking these films. The assessment of mechanical output for the FSMA thin film actuators have been done with a multiscale model, which allowed for concurrent simulation of the phenomena at atomic and mesoscale.
Design of a Leaf Spring Suspension for an FSAE Vehicle
Authors: Braghin Francesco , Sabbioni Edoardo , Annoni Francesco
Published: May 2009

FSAE is a competition in which engineering students are asked to conceive, design, fabricate and compete with small, formula style, autocross racing cars ([1]). To give teams the maximum design flexibility and the freedom to express their creativity and imaginations there are very few restrictions on the overall vehicle design. DynamiΣ team (from Politecnico di Milano) has designed and optimized a new leaf spring suspension that allows to significantly reduce the weight and lower the centre of gravity of traditional suspensions that are based on linear dampers and coil springs. In fact, besides being extremely adjustable, the proposed leaf spring suspension weights a half, being made of carbon fiber and aluminum sandwich, and lowers the centre of gravity of the suspension system, being placed below the vehicle frame.
A Hybrid Method for Surrogate Model Updating in Engineering Design Optimization
Authors: Shao Tiefu , Krishnamurthy Sundar
Published: May 2009

This paper addresses the critical issue of effectiveness, efficiency, and reliability in simulation-based design optimization under surrogate model uncertainty. Specifically, it presents a novel method to build surrogate models iteratively with sufficient fidelity for accurately capturing global optimal design solutions at a minimal cost. The salient feature of the proposed method lies in its unique preference of focusing necessarily high fidelity at potential global optimal regions of surrogate models. The proposed method is the synergic integration of the multiple preference point method, which updates surrogate model at current local optimal points predicted with data-mining techniques in genetic algorithm setup, and the maximum variance point method, which updates surrogate model at the point associated with the maximum prediction variance. Through illustrative comparison studies on thirty different optimization scenarios derived from 15 different test functions, the proposed method demonstrates the tangible reliability advancement. The experimental results indicate that the proposed method can be a reliable updating method in surrogate-model-based design optimization for efficiently locating the global optimal point/points in various kinds of optimization scenarios featured by single/multiple global optimal point/points that may exist at the corners of design space, inside design space, or on the boundaries of design space.
Geometric Modeling of Cutter/Workpiece Engagements for Helical Milling With Flat End Mills
Authors: Aras Eyyup , Yip-Hoi Derek
Published: May 2009

Helical milling is a 3-axis machining operation where a cutting tool is feed along a helix. This operation is used in ramp-in and ramp-out moves when the cutting tool first engages the workpiece, for contouring and for hole machining. It is increasingly finding application as a means for roughing large amounts of material during high speed machining. Modeling the helical milling process requires cutter/workpiece engagements (CWEs) geometry in order to predict cutting forces. The calculation of these engagements is challenging due to the complicated and changing intersection geometry that occurs between the cutter and the in-process workpiece. In this paper we present a geometric modeling methodology for finding engagements during helical milling with flat end mills. A mapping technique has been developed that transforms a polyhedral model of the removal volume from Euclidean space to a parametric space defined by location along the tool path, engagement angle and the depth-of-cut. As a result, intersection operations are reduced to first order plane-plane intersections. This approach reduces the complexity of the cutter/workpiece intersections and also eliminates robustness problems found in standard polyhedral modeling and improves accuracy over the Z-buffer technique. The reported method has been implemented and tested using a combination of commercial applications. This paper highlights ongoing collaborative research into developing a Virtual Machining System.
Robust Control System Design for Multivariable Plants With Lightly Damped Modes
Authors: Nelson-Gruel D. , Lanusse P. , Oustaloup A. , Pommier V.
Published: May 2009

A robust controller design is proposed for the active suspension system bench-mark problem. The CRONE control system design used is extended to unstable multivariable plants with lightly damped modes and RHP zeros. Decoupling and stabilizing controller K, is achieved for the open-loop transfer matrix. Fractional order transfer functions are used to define all the components of the diagonal open-loop transfer matrix, β. In defining the fractional open-loop transfer function β0i some elements of the plants, G0 and its inverse must be considered to achieve the stable controller. Optimisation provides the best fractional open-loop βopt. Finally, frequency domain system identification is used to find controller K=G0−1 βopt.
Synthesis of Adaptive Pliers Mechanism Using Genetic Algorithms
Authors: Szydlowski Wieslaw M. , Nelson Carl A.
Published: May 2009

A Genetic Algorithms (GA) approach to dimensional synthesis of an adaptive pliers mechanism is presented. Satisfaction functions are implemented in a custom C++ algorithm to enforce ergonomic and force-transmission goals. Using various values of selection rate and crossover rate, along with a “diversity monitor,” many solutions are found which are functionally superior to the original mechanism.
From Origami to a New Class of Centralized 3-DOF Parallel Mechanisms
Authors: Rodriguez Leal Ernesto , Dai Jian S.
Published: May 2009

This paper applies the ‘technomimetics’ concept to generate a new class of parallel mechanisms inspired by origami folds. This new class of 3-DOF (Degree of Freedom) parallel mechanisms is constructed with 3-RPRP architecture. When the geometric constraints mentioned in this paper are applied, the mechanisms will be allowed to rotate around the x and y axes and translate vertically along the z axis, while the centre of the platform remains concentric to the centre of its base. This paper investigates both position and geometry of these mechanisms and identifies the closed form solutions for the inverse kinematics problem. The differential kinematical analysis is developed by deriving the Jacobian matrix through screw theory and the singularities are identified with workspace analysis. The paper ends with isotropic configuration analysis and illustrates the characteristics of the new mechanisms.
Reliable Space Pursuing for RBDO With Black-Box Performance Functions
Authors: Shan S. , Wang G. Gary
Published: May 2009

Reliability-based design optimization (RBDO) is intrinsically a double-loop procedure since it involves an overall optimization and an iterative reliability assessment at each search point. Due to the double-loop procedure, the computational expense of RBDO is normally very high. Current RBDO research is focused on performance functions having explicit analytical expression and readily available gradients. This paper addresses a more challenging type of RBDO problem in which the performance functions are computation intensive. These computation intensive functions are often considered as a “black-box” and their gradients are not available or not reliable. Based on the reliable design space (RDS) concept proposed earlier by the authors, this paper proposes a Reliable Space Pursuing (RSP) approach, in which RDS is first identified and then gradually refined while optimization is performed. It theoretically avoids the nested optimization and probabilistic assessment loop. This approach can apply to RBDO problems with either analytical or blackbox performance functions. Three well known numerical problems from the literature are used to test and demonstrate the effectiveness of RSP.
An Implicit Time-Stepping Method for Quasi-Rigid Multibody Systems With Intermittent Contact
Authors: Chakraborty Nilanjan , Berard Stephen , Akella Srinivas , Trinkle Jeff
Published: May 2009

We recently developed a time-stepping method for simulating rigid multi-body systems with intermittent contact that is implicit in the geometric information [1]. In this paper, we extend this formulation to quasi-rigid or locally compliant objects, i.e., objects with a rigid core surrounded by a compliant layer, similar to Song et al. [2]. The difference in our compliance model from existing quasi-rigid models is that, based on physical motivations, we assume the compliant layer has a maximum possible normal deflection beyond which it acts as a rigid body. Therefore, we use an extension of the Kelvin-Voigt (i.e. linear spring-damper) model for obtaining the normal contact forces by incorporating the thickness of the compliant layer explicitly in the contact model. We use the Kelvin-Voigt model for the tangential forces and assume that the contact forces and moment satisfy an ellipsoidal friction law. We model each object as an intersection of convex inequalities and write the contact constraint as a complementarity constraint between the contact force and a distance function dependent on the closest points and the local deformation of the body. The closest points satisfy a system of nonlinear algebraic equations and the resultant continuous model is a Differential Complementarity Problem (DCP). This enables us to formulate a geometrically implicit time-stepping scheme for solving the DCP which is more accurate than a geometrically explicit scheme. The discrete problem to be solved at each time-step is a mixed nonlinear complementarity problem.