bluuebunny/crossref_metadata_2025 huggingface dataset:
Haptic Feedback Applied to Pneumatic Walking
Authors: Guerriero Brian , Book Wayne
Published: July 2009

This paper presents a proposed control method for controlling the foot positions of two robotic legs through direct operator inputs with haptic feedback. The robot consists of two 3-DoF legs driven by pneumatic actuators. A demonstration of the controller shows the tracking performance enhancements of the proposed force-based position controller over a simple differential pressure gain scheduler-based position controller. The proposed controller incorporates pressure feedback to create supplementary force control. Foot position tracking remains within 10% of the commanded reference position, even through the sharp disparities of loading conditions as the actuators are either lifting the weight of the legs or supporting the weight of the robot itself. An operator gives direct foot position commands to the controller through two PHANToM haptic devices. Bilateral teleoperation of the system provides directional force feedback to the operator as a function of foot position error. The proposed controller also decreases the ambient and false forces reflected to the operator while moving the legs through gait cycles.
State Feedback Stabilization of Networked Control Systems With Random Time Delays and Packet Dropout
Authors: Yu Bo , Shi Yang
Published: July 2009

This article considers the state feedback controller design in the networked control systems (NCSs). The network-induced random time delays and packet dropout existing in sensor-to-controller (S-C) and controller-to-actuator (C-A) links are modeled by two Markov chains. The controller incorporates not only the current S-C delay but also the most recent C-A delay to exploit all available information. Then, the system is converted to be a special jump linear system. The sufficient and necessary conditions for stochastic stability are derived and the state feedback stabilization problem is formulated to be an optimization problem solved by the iterative linear matrix inequality (LMI) approach. A design example is given to illustrate the effectiveness of the proposed method.
Articulated Wheeled Robots: Exploiting Reconfigurability and Redundancy
Authors: Fu Qiushi , Krovi Venkat
Published: July 2009

Articulated Wheeled Robotic (AWR) locomotion systems consist of chassis connected to a set of wheels through articulated linkages. Such articulated “leg-wheel systems” facilitate reconfigurability that has significant applications in many arenas, but also engender constraints that make the design, analysis and control difficult. We will study this class of systems in the context of design, analysis and control of a novel planar reconfigurable omnidirectional wheeled mobile platform. We first extend a twist based modeling approach to this class of AWRs. Our systematic symbolic implementation allows for rapid formulation of kinematic models for the general class of AWR. Two kinematic control schemes are developed which coordinate the motion of the articulated legs and wheels and resolve redundancy. Simulation results are presented to validate the control algorithm that can move the robot from one configuration to another while following a reference path. The development of two generations of prototypes is also presented briefly.
A Comparative Study of Feedforward Tuning Methods for Wafer Scanning Systems
Authors: Stearns Hoday , Yu Shuwen , Fine Benjamin , Mishra Sandipan , Tomizuka Masayoshi
Published: July 2009

The use of feedforward control is beneficial for high-performance trajectory tracking in many motion control systems. Three methods of designing and tuning feedforward control signals (Iterative Learning Control, Iterative Controller Tuning, and Adaptive Feedforward Control) for a wafer scanner system are presented and compared. For this application, the main sources of tracking error are due to phase mismatch and nonlinear force ripple disturbance. The objective is to compare the performance of these three methods in compensating for error arising from these sources. The methods are compared based on a set of metrics. Comparison is followed by a discussion on advantages and disadvantages of each method including ability to reduce error during acceleration or scan phases of the trajectory, necessary assumptions, effect of inaccurate modeling, and effect of noise.
Underwater Vehicle Autopilots With Adaptive Dynamic Surface Control
Authors: Zheng Zhibo , da Silva Jorge Estrela , de Sousa Joa˜o B. , Girard Anouck R.
Published: July 2009

This paper presents an overview of the state-of-the-art for underwater vehicle autopilots. We start by reviewing reference frames, vehicle states, typical control surfaces, equations of motion, the different coefficients and how they are obtained, and disturbance models as well. We then consider different possible configurations for the autopilot, including decoupled lateral and longitudinal loops, maneuver and waypoint control. Adaptive dynamic surface control of nonlinear tracking of a single underwater vehicle is designed with the corroboration with numerical simulations. Finally, we describe current hardware implementations for autonomous underwater vehicles.
Adaptive Sliding Mode Tracking of Nonlinear Plants With Multiple Unknown Time-Varying State Delays
Authors: Mirkin Boris , Gutman Per-Olof , Shtessel Yuri
Published: July 2009

In this paper, we develop a sliding mode model reference adaptive control (MRAC) scheme for a class of nonlinear dynamic systems with multiple time-varying state delays which is robust with respect to unknown plant delays, to a nonlinear perturbation, and to an external disturbance with unknown bounds. An appropriate Lyapunov-Krasovskii type functional is introduced to design the adaptation algorithms, and to prove stability.
Mutual Identifiability Analysis for Parameter Signature Isolation in the Time-Scale Plane
Authors: Danai Kourosh , McCusker James R. , Hollot C. V.
Published: July 2009

It was shown recently that regions in the time-scale plane can be isolated wherein the prediction error can be attributed to the error of an individual model parameter. A necessary condition for this isolation capacity is the mutual (pairwise) identifiability of the model parameters. This paper presents conditions for mutual identifiability of parameters of linear models and refines these conditions for models that exhibit rank-1 dependency on the parameters.
Teaching Automatic Control of Engineering Systems Using Open Source CH Control System Toolkit and Web-Based Design and Analysis System
Authors: Chen Bo , Chou Yu-Cheng , Cheng Harry H.
Published: July 2009

Ch Control System Toolkit (CCST) is a software package for design and analysis of control systems. It is implemented as a class with member functions to run in the user-friendly C/C++ interpreter Ch. Based on the CCST, a Web-based Control System Design and Analysis System (WCDAS) has been developed. In this article, using CCST and WCDAS to teach automatic control of engineering systems is presented. Using CCST, students are able to write programs easily with a few lines of C/C++ code to solve practical engineering problems. By solving control system design and analysis problems in C/C++, the programming skills gained in the course are applicable to other areas of engineering. CCST and WCDAS are open source. Students are able to examine the source code to understand the implementation of theories and algorithms in software. Based on CCST and WCDAS, the Web-based Controller/Compensator Design Module (WCCDM) has also been developed for teaching and student learning. Using these Web-based tools, students can perform design and analysis of control systems interactively through a Web browser remotely. The CCST, WCDAS, and WCCDM have been used to teach an undergraduate course on Automatic Control of Engineering Systems at the University of California, Davis. All software packages and teaching materials for this course are available on the internet. They can be downloaded and modified to teach similar courses with different requirements.
Higher-Order Experimental Haptic Force Models of Mechanical Devices Using Moving Ridge Regression
Authors: Judd Mark A. , Colton Mark B.
Published: July 2009

Accurate modeling of physical devices is one of the keys to improving the realism of haptic simulations. This paper presents general, locally linear haptic force models to describe the feel of complex mechanical systems that exhibit nonlinear static and dynamic behavior. The parameters of these models are estimated from experimental data using moving ridge regression. Nonlinear variations of the locally linear model are presented and analyzed, and the goodness-of-fit of these models is compared. Initial results suggest that higher-order terms do little to improve the quality of this class of haptic models, and that reduced-order models should be further investigated.
Neural Network Control of a Robot Interacting With an Uncertain Hunt-Crossley Viscoelastic Environment
Authors: Bhasin S. , Dupree K. , Patre P. M. , Dixon W. E.
Published: July 2009

The objective in this paper is to control a robot as it transitions from a non-contact to a contact state with an unactuated viscoelastic mass-spring system such that the mass-spring is regulated to a desired final position. A nonlinear Hunt-Crossley model, which is physically consistent with the real behavior of the system at contact, is used to represent the viscoelastic contact dynamics. A Neural Network feedforward term is used in the controller to estimate the environment uncertainties, which are not linear-in-parameters. The NN Lyapunov based controller is shown to guarantee uniformly ultimately bounded regulation of the system despite parametric and nonparametric uncertainties in the robot and the viscoelastic environment respectively. The proposed controller only depends on the position and velocity terms, and hence, obviates the need for measuring the impact force and acceleration. Further, the controller is continuous, and can be used for both non-contact and contact conditions.
Robust Controller Design to Achieve Active Damping for a MEMS Microphone
Authors: Qu Jinli , Miles Ronald N. , Wu N. Eva
Published: July 2009

This paper presented an H∞-controller design to achieve active damping for a MEMS microphone system. The parametric uncertainties introduced by linearization process were modeled. The stability and performance of the closed-loop system were analyzed for the uncertain microphone model and both were shown to be robust. The nonlinear simulation further verifies that the controller offers the desired performance.
Longitudinal Vehicle Dynamics Scaling and Implementation on a HIL Setup
Authors: Verma Rajeev , Del Vecchio Domitilla , Fathy Hosam K.
Published: July 2009

This paper presents the application of Buckingham’s π theorem to scale the powertrain of a High Mobility Multipurpose Wheeled Vehicle (HMMWV) by deriving non dimensional ratios called π parameters. A Hardware In the Loop (HIL) setup is constructed and the resulting longitudinal dynamics of the scaled vehicle are validated against those of a full scale vehicle model. This is performed with the ultimate goal of testing cooperative collision avoidance algorithms on a testbed comprising a number of these scaled vehicles. This paper is based on “Development of a scaled vehicle with Longitudinal dynamics of a HMMWV for ITS testbed”, by Verma, R., Domitilla Del Vecchio, and Hosam K. Fathy which appeared in IEEE/ASME Transactions on Mechatronics, February 2008 and is being reprinted with permission from IEEE.
A Stochastic Optimal Control Approach for Power Management in Plug-In Hybrid Electric Vehicles
Authors: Moura Scott J. , Fathy Hosam K. , Callaway Duncan S. , Stein Jeffrey L.
Published: July 2009

This paper examines the problem of optimally splitting driver power demand among the different actuators (i.e., the engine and electric machines) in a plug-in hybrid electric vehicle (PHEV). Existing studies focus mostly on optimizing PHEV power management for fuel economy, subject to charge sustenance constraints, over individual drive cycles. This paper adds three original contributions to this literature. First, it uses stochastic dynamic programming to optimize PHEV power management over a distribution of drive cycles, rather than a single cycle. Second, it explicitly trades off fuel and electricity usage in a PHEV, thereby systematically exploring the potential benefits of controlled charge depletion over aggressive charge depletion followed by charge sustenance. Finally, it examines the impact of variations in relative fuel-to-electricity pricing on optimal PHEV power management. The paper focuses on a single-mode powersplit PHEV configuration for mid-size sedans, but its approach is extendible to other configurations and sizes as well.
Parametrization of All Stabilizing LTI Controllers for Multirate SISO Systems
Authors: Cimino M. , Pagilla P. R.
Published: July 2009

In this work we provide a solution for the problem of parametrization of all stabilizing LTI controllers for multirate SISO systems. This problem has been previously addressed with the use of the lifting technique which can be utilized to convert a linear multirate system into a single-rate higher-order system. We propose a new procedure to solve the problem without lifting the multirate system. The new approach reduces the computational effort and restrict the solution to the set of all stabilizing LTI controllers. The non-commutative property of the down-sampling operation is the main obstacle to solve the problem. To overcome this difficulty we transform the problem by rewriting the controller transfer function using the modified Z-transform. This facilitates the separation of plant and controller dynamics in the closed-loop characteristic polynomial. Tools from the modified Z-transform method and control synthesis using the Diophantine equation are utilized to solve the problem for multirate systems. Moreover, by using the Diophantine equation the result is extended to the set of all stabilizing controllers for which the multirate system exhibits a dead-beat response.
Proportional Pressure Control of Water Hydraulic System for Water-Assisted Injection Molding: Modeling and Simulation
Authors: Zhang Zengmeng , Zhou Hua
Published: July 2009

The proportional pressure control of water hydraulic system for water-assisted injection molding (WAIM) is investigated through modeling and simulation. WAIM is an innovative process to mold plastic parts with hollow sections. A water hydraulic system is designed for WAIM and a differential pressure control strategy is provided to regulate the water injection pressure by a proportional relief valve. An accumulator and a pressure cylinder are applied in the system and modeled in MATLAB. The load characteristic is analyzed and the coupling relationship between load pressure and flow rate is approximately simulated. Based on the variable-parameter model with linearization, open-loop and closed-loop control with multi-point feedback are investigated. Integral compensation and PI control are used with slope control of injection pressure. In addition, the influence of load characteristic is also investigated. Results of the simulation show that the closed-loop control contributes to the stability and disturbance resistance performance under various load characteristics.
Iterative Learning Control of Mechanical Systems With Slow Sampling Rate Position Measurements
Authors: Wang Chun-Chih , Tomizuka Masayoshi
Published: July 2009

This paper deals with the iterative learning controller design problem with slow sampling rate position measurements. In some applications, it is desired to implement the learning controller at a sampling rate higher than that of the measurement. Two approaches are presented in this paper to solve the learning controller design problem. The first approach utilizes an interlacing technique to obtain the slow sampling rate position measurement, and update the learning controller at the desired sampling rate using only the available slow sampling rate measurement. The second approach uses a multirate kinematic Kalman smoother to obtain the position estimate at the desired sampling rate by fusing the position measurement and additional acceleration measurements at fast sampling rates. The effectiveness of the two approaches is demonstrated by experiments.
Design and Modeling of a Petal-Shape, Conjugated Polymer-Actuated Micropump
Authors: Fang Yang , Tan Xiaobo
Published: July 2009

Conjugated polymers are emerging actuation materials for biomimetic robots and biomedical devices. Most previous research has been focused on the configurations of cantilever beams and linear extenders. However, the diaphragm configuration is needed in many potential applications, such as micro pumps for drug delivery and chemical/ biological analysis. In this paper the design of a conjugated polymer pumping diaphragm is investigated theoretically and experimentally. A petal-shape design is proposed to alleviate the edge constrains. Transfer function models from the actuation voltage to the diaphragm curvature and to the flow rate are obtained. Experiments are conducted to verify the effectiveness of the models. The transfer function models facilitate design optimization and the use of feedback control tools in dealing with the complicated behavior of conjugated polymer actuators.
A “Smart Tire” System for Tire/Road Friction Estimation
Authors: Yi Jingang , Tseng Eric H.
Published: July 2009

In this paper, we present the development of a tire deformation sensing system that can provide the critical information for estimation of tire/road interaction for mobile robots and vehicles. Polyvinylidene fluoride (PVDF)-based sensor is designed and fabricated to embed on the inner tread surface to measure the rubber tread deformation. Analytical models of the PVDF-based sensing system are presented to capture the tire/road contact information and friction characteristics. The sensed deformation measurements are integrated with the on-board control system through a wireless data transmission module. Experimental results on a skid-steered mobile robot are presented to show the feasibility of the developed sensing system.
DDE Model of Gene Expression: A Continuum Approach
Authors: Verdugo Anael , Rand Richard H.
Published: July 2009

This paper presents an analytical study of the stability of the steady state solutions of a gene regulatory network with time delay. The system is modeled as a continuous network and takes the form of a nonlinear delay differential-integral equation coupled to an ordinary differential equation. Two examples are given in which the critical delay causing instability is computed.
Two-Vortex Models for Vortex Breakdown
Authors: Blackmore Denis , Goullet Arnaud , Bro̸ns Morten
Published: July 2009

A simple Hamiltonian dynamical systems model for vortex breakdown of the bubble-type (B-type) is developed and analyzed. This model is constructed using the flow induced by two point vortices moving in a half-plane immersed in an ideal (= inviscid and incompressible) fluid with an ambient uniform horizontal velocity. It is shown — using a combination of modern dynamical systems theory and numerical analysis — that the flows generated by this model capture most of the dynamical features exhibited in B-type vortex breakdown, including the existence of chaotic regimes. Examples are provided to illustrate the variety and complexity of vortex breakdown type flows that can be produced with these models.
Inertial Swimming as a Singular Perturbation
Authors: Childress Stephen
Published: July 2009

The swimming of a sheet, originally treated by G.I. Taylor (1951) for the case of Stokes flow, is considered at moderate and high Reynolds numbers using matched asymptotic expansions. It is shown that for propagating waves with frequency ω, wavenumber k, and amplitude b, the swimming speed must be deduced from a dual expansion in powers of the small parameters bkR1/2 and R−1/2, where R = ω/νk2 is the Reynolds number. The result of Tuck (1968) for the leading term of the swimming velocity is recovered, and higher-order results are given. For the case of a planar, stretching sheet, the expansion is in powers of bk and R−1/2 and a limit for large R is obtained as a boundary layer. We contrast these results with the inviscid case, where no swimming is possible. We also consider briefly the application of these ideas to “recoil swimming”, wherein the movements of the center of mass and center of volume of a body allow swimming at both finite and infinite Reynolds numbers.
Modeling the Rapid Transmission of Information Within a Social Group of Insects: Emergent Patterns in the Antipredator Signals
Authors: Borduin Russell , Ramaswamy Karthik , Mohan Ashwin , Cocroft Rex , Nair Satish S.
Published: July 2009

The study of group behavior in animals emerging from social interactions among individuals using agent based models has gained momentum in recent years. Although most of the individuals in a group of the treehopper Umbonia crassicornis do not have information about where the predator is, the signaling behavior of the group yields an emergent pattern that provides the defending adult with information about predator presence and location. Offspring signal synchronously to warn a defending parent of a predator attack. We develop a computational model of rapid signaler-receiver interactions in this group-living insect. We test the emergence of informative global patterns by providing interacting juvenile nymphs with limited locally available information with this agent based model. Known parameters such as size of the aggregation and spatial distribution are estimated from experimental recordings. Further, the model investigates the behavioral rules underlying group signaling patterns that reveal the predator’s location. We also show how variation in these behavioral rules can bring about variation in group signals, demonstrating the potential for natural selection to shape these rules.
Stability Analysis of Three-Agent Consensus Dynamics With Fixed Topology and Three Non-Identical Delays
Authors: Sipahi Rifat , Acar Artug
Published: July 2009

In this paper, we consider a strongly connected three-agent consensus dynamics with three non-identical communication delays, where each delay arises between a pair of agents. Asymptotic stability of consensus mission is of question in presence of delays, and to study this we propose a new and computationally efficient technique that detects stability transitions with respect to delays. This new technique originates from frequency sweeping ideas and ultimately leads to stability robustness maps of the system with respect to three delays. Proofs related to the analysis are sketched. A case study is provided to demonstrate the effectiveness of the approach and the trade-off between controller gains versus delays.
Experimental Study of Static Friction in a Spherical Elastic-Plastic Contact
Authors: Ovcharenko Andrey , Halperin Gregory , Etsion Izhak
Published: July 2009

The elastic-plastic contact between a deformable sphere and a rigid flat during pre-sliding is studied experimentally. Measurements of friction force and contact area are done in real time along with an accurate identification of the instant of sliding inception. The static friction force and relative tangential displacement are investigated over a wide range of normal preloads for several sphere materials and diameters. It is found that at low normal loads the static friction coefficient depends on the normal load in breach of the classical laws of friction. The pre-sliding displacement is found to be less than 5 percent of the contact diameter, and the interface mean shear stress at sliding inception is found to be slightly below the shear strength of the sphere material. Good correlation is found between the present experimental results and a recent theoretical model in the elastic-plastic regime of deformation.
Studies on Friction and Formation of Transfer Layer in HCP Metals
Authors: Menezes Pradeep L. , Kishore  , Kailas Satish V.
Published: July 2009

Surface texture plays an important role as it predominantly controls the frictional behavior and transfer layer formation at the contacting surfaces. In the present investigation, basic studies were conducted using inclined pin-on-plate sliding tester to understand the role of surface texture of hard material on coefficient of friction and transfer layer formation when sliding against soft materials. HCP materials such as pure Mg and pure Zn were used as pins while 080 M40 steel was used as plate in the tests. Two surface parameters of steel plates — roughness and texture — were varied in the tests. Tests were conducted in ambient conditions under both dry and lubricated conditions. The morphologies of the worn surfaces of the pins and the formation of transfer layer on the counter surfaces were observed using a scanning electron microscope. It was observed for both the pin materials that the occurrence of stick-slip motion, the transfer layer formation and the value of coefficient of friction as well as its two components, namely, adhesion and plowing, depend primarily on surface texture. The effect of surface texture on coefficient of friction was attributed to the variation of plowing component of friction for different surfaces. Both the plowing component of friction and amplitude of stick-slip motion were highest for the surface texture that promotes plane strain conditions while these were lowest for the texture that favors plane stress conditions at the interface.
Robust-Satisficing in Engineering Design
Authors: Ben-Haim Yakov
Published: July 2009

Hammurabi’s Code of Law imposed extreme penalties for design failures, providing strong incentives for ancient engineers to meet design specs. Engineers today still bear legal liability for design failure, though less severely than in ancient Babylonia. Why does the engineering profession commonly specify performance requirements as inequality constraints, rather than specifying constrained-optimal design? To “satisfice” means to “meet expectations or specifications”. Why do engineers satisfice rather than optimize performance requirements? The answer we present is based on design in the face of severe uncertainty. We use info-gap decision theory to formulate a design strategy: robust-satisficing. We discuss the relation between robust-satisficing and min-maxing, and we discuss a simple example.
Nb-Doped Barium Titanate: Concentration-Properties Relations
Authors: Hershkovitz Shany , Baltianski Sioma , Tsur Yoed
Published: July 2009

Nb doped barium titanate (BT) experiences unique phenomena over a range of dopant concentrations. One important phenomenon is the resistivity behavior as a function of donor concentration. The role of the grains and the grain boundaries in this system is not fully established yet. There are diverse opinions on this subject, since this system is usually only in partial equilibrium and hence very complex. We examine the system using Impedance Spectroscopy (IS). Two new analysis methods for IS based on evolutionary programming techniques, which are inspired by biological evolution, have been developed in our lab. Those evolutionary programming techniques are called Genetic Programming (GP) and Genetic Algorithm (GA). This is an approach to solve (or in the case of GA suggest solution for) such ill-posed inverse problems. By implementation and improvement of the use of those techniques for analyzing IS results, we believe that the role of the grains and the grain boundaries can be separated and the physical processes occur can be analyzed.
Iterative Feedback Tuning for Nonlinear Systems Based on Identification of Linearized Time-Varying Models
Authors: Sjo¨berg Jonas , Gutman Per-Olof , Agarwal Mukul , Bax Mike
Published: July 2009

A novel algorithm for tuning controllers for nonlinear plants is presented. The algorithm iteratively minimizes a criterion of the control performance. For each controller update iteration, one experiment is performed with a reference signal slightly different from the previous reference signal. The input-output signals of the plant are used to identify a linear time-varying model of the plant which is then used to calculate an update of the controller parameters. The algorithm requires an initial feedback controller that stabilizes the closed loop for the desired reference signal and in its vicinity, and that the closed-loop outputs are similar for the previous and current reference signals. The tuning algorithm is successfully tested on a laboratory set-up of the Furuta pendulum.
Friction and Wear of MoS2 Films on Laser Textured Steel Surfaces
Authors: Rapoport Lev , Moshkovich Alexey , Perfilyev Vladislav , Lapsker Igor , Halperin Gregory , Itovich Yan , Etsion Izhak
Published: July 2009

Incorporation of solid lubricant into micro-reservoirs produced by Laser Surface Texturing (LST) and its effect on the tribological properties of surfaces under dry friction is studied. The density of the dimple reservoirs and the height of the bulges around them are investigated in terms of the longevity of solid lubricant films burnished on LST steel surfaces. Friction tests were performed using a ball-on-flat device. Optimum density (40–50%) of the dimples is revealed. It is shown that the adhesion of solid lubricant in the space between the dimples is provided by mechanical engagement of particles in the rough surface and by smearing the solid lubricant around the dimples. Best results are obtained with the surfaces that were lapped to half of the height of bulges. Long wear life of burnished film on LST steel surfaces is apparently provided by preservation of thin MoS2 film around the bulges and by supply of solid lubricant from the dimples to the surface. The effect of repeated burnishing on wear life of solid lubricant films was studied. Repeating burnishing leading to increasing the density of solid lubricant films increases the wear life.
Correlating the Features of Topography to Friction by Sliding Experiments
Authors: Pottirayil Anirudhan , Menezes Pradeep L. , Kailas Satish V.
Published: July 2009

Friction can influence the quality of the finished product to a large extent in certain manufacturing processes. Sheet metal forming is a particular case, where the friction between the hard-die and the relatively soft work-piece can be extremely important. Under such conditions, topography of the harder surface can influence the resistance to traction at the interface. This paper discusses about the correlation between certain features of the surface topography and coefficient of friction based on experiments involving sliding of a few soft metal pins against a harder material. A brief description of the experimental procedure and the analysis are presented. A hybrid parameter which encapsulates both the amplitude features as well as the relative packing of peaks is shown to correlate well with the coefficient of friction.
Future Vehicle Stability Control Systems for Motorcycles With Focus on Accident Prevention
Authors: Seiniger P. , Winner H. , Gail J.
Published: July 2009

Vehicle Stability Control systems (VSC) for four-wheeled vehicles like the electronic stability program (ESP) helped to decrease the number of traffic deaths in Germany to an all-time low over the last ten years. However, the number of people killed in powered two-wheeler accidents has been almost constant over the same period of time. Vehicle Stability Control systems for powered two-wheelers (especially motorcycles) so far include only anti-lock brakes and traction control systems, both systems are not designed to work in cornering. Further stability control systems are not known up to now. The objective of this paper is to assess the technical possibilities for future Vehicle Stability Control systems and the amount of accidents that could be prevented by those systems. From an accident analysis, all accidents not avoidable by today’s VSC Systems have been analyzed. Only accidents while cornering without braking have been determined as potentially avoidable by future technical systems (braked accidents have been counted as preventable by improved today’s systems). The accidents can be caused by insufficient friction (e.g. slippery road surface, sand, oil or to high curve speed). About 4 to 8 percent of all motorcycle accidents are of this type. The data source for accident descriptions were interviews of motorcycle experts who were able to describe their own accidents and detailed accident descriptions from an accident database. The accident types have been investigated with driving experiments and computer simulation. With a vehicle model different ways to influence the critical driving situations could be analyzed and evaluated. Experiments and simulations showed an instable roll and side-slip angular acceleration of the motorcycle during critical driving situations. The sideslip rate proved to be a robust criterion for recognizing whether a driving situation is critical. The roll movement of the vehicle cannot be influenced with reasonable means, because neither the lateral tire forces can be increased nor stabilizing gyros can be used since the necessary angular momentum is to large for a feasible package. The vehicle sideslip rate can be influenced by braking the front or the rear wheel, thus generating a yaw moment to avoid the dangerous high-side type accidents when friction changes back from low to high. The motorcycle accidents influenced by this system are only a small portion of the mentioned accidents, so as a result of this study, the potential for future vehicle dynamic control systems that help prevent non-braking cornering accidents is estimated quite low.
Loading-Unloading of an Elastic-Plastic Adhesive Spherical Contact
Authors: Kadin Yuri , Kligerman Yuri , Etsion Izhak
Published: July 2009

A numerical solution is presented for a single load-unload cycle of an adhesive contact between an elastic-plastic sphere and a rigid flat. The interacting forces between the sphere and the flat are obtained through connecting non-linear spring elements having force-displacement behavior that obeys the Lennard-Jones potential. Linear kinematic hardening (with tangent modulus of 2% and 5% of the Young’s modulus) rather than isotropic hardening is assumed for the sphere material to account for possible secondary plastification during the unloading. The well known Tabor parameter and a plasticity parameter are shown to be the two main dimensionless parameters governing the problem. The effects of these two parameters on the load-approach curves, on the plastically deformed sphere profiles and on the plastic strain fields inside the sphere are presented, showing different modes of separation during the unloading.
Features of Flexible E-Learning Modules Within Geographical Information Science for Vocational Training
Authors: Parseliunas Eimuntas , Urbanas Saulius
Published: July 2009

The main features and general structures of two distant learning modules within geographical information science for vocational training are presented in this paper. “European Level Developments of Flexible Learning Models within Geographical Information Science (GIS) for Vocational Training (E-GIS)” was a pilot project under the Leonardo de Vinci Community action Programme on vocational training, within Geographical Information Science (GIS), to be implemented over a three year period, 2002–05. The project will be continued in 2008–2009 under the abbreviation eGIS+. The main objectives of the project is to establish co-operation between European Universities and GIS user organisations and to develop modularised courses intended for Internet based learning, establish links of communications between the partners in the project in order to disseminate and share “best practices” in different teaching situations and for different types of students. The course modules to be developed, all together, will constitute a one-year programme within GIS. This project mainly targets full time students, private and civil service employees within the European Union, but also similar categories in non-EU countries. The outcomes of the project is high level content, new net-based pedagogic method suited for accessing target groups of great diversity as regards pedagogic traditions, access to computers and bandwidth. Cooperation between the institutions will, certainly, give higher level courses than the individual institutions could possibly themselves. “Training of Lithuanian Geographic Information Infrastructure managers” is a project supported by European Union Structural Funds and National Land Service under the Ministry of Agriculture of Lithuania Republic. The main objective of the proposed geographic information e-training system is to develop and provide the modularised Spatial Information Infrastructure courses intended for on-line based learning. This mainly will target employees of civil service and private business in Lithuania and European Union. Proposed curriculum is a set of modular courses adding up to 1.5-year part-time studies in the field of Geographic Information Science and Geographic Information Infrastructure.
Teaching Reconfigurable Systems by RAM-Based FSM Designing
Authors: Abramov Binyamin , Ostrovsky Vladimir , Poltek Ronen
Published: July 2009

Reconfigurable systems have the potential to boost hardware performance, efficiency and to stimulate development activity by enabling designers to work with flexible “modeling clay”, rather than with fixed units of hardware. One of the design issues not widely covered in current Advanced Logic Design courses is the issue of reconfigurable systems design. The proposed pedagogical approach enables the achievement of reconfigurable electronic systems representations through Finite State Machine (FSM), and may be helpful for teaching disciplines, in subjects such as reconfigurable computing and advanced digital systems. The approach intends to cover topics such as architectures and capabilities of field-programmable logic devices; system specification, modelling, and synthesis of digital systems; design methodology; computer-aided design tools; reconfiguration techniques. FSMs are probably the most widely used control components in digital systems. The accepted FSM design methodology taught today is problem oriented, especially its combinatorial part. This approach makes changes to the design complicated and undesirable. In contrast, in the new suggested approach, the emphasis is on the automata behavior and not on its implementation logic. The result of this approach is a more flexible and less complicated design abilities that uplift the course to a more intense and focused levels while enabling at the same time to perform a larger amount of experiments, and enhance the students’ self-efficacy. The proposed design method for FSM implementation with both combinational part and state memory part is built primarily from RAM blocks. The basic components of the circuit are utilizing the FPGA’s RAM blocks, by reprogramming these one can provide for different functionality. The design procedure is automated by software shell that converts the FSM representation in Kiss2 format to a VHDL description that corresponds to the proposed architecture. This paper suggests methods for the design of a reconfigurable FSM to be used in Advanced Logic Design course, and deals with the following aspects: a) system formalization by high (behavioral) level of abstraction; b) RAM based FSM architecture; c) reusable templates d) software system for FSM static reconfiguration. In addition, the proposed approach enables non-hardware background people to be able to control algorithm representation as FSMs and it also provides an additional motivation for students since the reconfigurable systems concept may be linked to studies in other disciplines; and a dynamic reconfiguration is overviewed.
Electromechanical Response of Large Strain Ferroelectric Actuators
Authors: Shilo Doron , Mendelovich Amir , Drezner Haika
Published: July 2009

One of the desired properties of actuators is large actuation strains, which also correlates with large work output per volume. This property becomes especially important in micro systems where small devices are required to produce relatively large strokes. The existing mechanisms for electromechanical actuation are limited to small actuation strains and hence recent years have seen a variety of attempts at achieving larger strain actuation. One such attempt, basing on 90 degree domain switching in ferroelectric crystals subjected to compression load and cyclic electric field, has recently been demonstrated. In this presentation we explore the dynamics of 90 degree domain switching at high frequencies. For this purpose a novel ferroelectric actuator and experimental system were developed, which allow measuring the response of a BaTiO3 single crystal to a combination of constant tensile stress and cyclic electric field at frequencies of up to 100 kHz. Experimental results are compared with theoretical calculations basing on a new model which considers the motion of discrete domain walls. Current results exhibit actuation strains of up to 0.8% (an order of magnitude larger than piezoelectric strains) and no decrease of actuation strains up to several kHz.
Using Threshold Functions in Teaching Electronics
Authors: Shafat Gabriel , Abramov Binyamin , Levin Ilya
Published: July 2009

Teaching of digital electronics and the teaching of analog electronics differ significantly. The methods in use today differ in two major points: the required mathematical background and the used didactic methods. The well-known gap between the analog and the digital paradigms in teaching electronics has motivated the present study. The paper introduces a novel approach for electronics course teaching. The approach uses a concept threshold functions. Threshold functions have three remarkable properties that are suitable for the purposes of teaching an electronics course. The first property is the simplicity of the functions’ representation and implementation; the essence of a threshold function is understandable on the common sense level. The second property is the dual analog-digital nature of the threshold functions. The definition of a threshold function usually includes both Boolean and arithmetic portions and weaves together the two alternative domains: digital and analog. Since students are familiar with regular arithmetic functions from previous math courses, the addition of Boolean concepts is simple to grasp. The possibility to transform any threshold function from one domain to another, serves as a powerful tool for processes teaching. The third property we consider is the multiple representations possible for threshold functions. Besides the classical Boolean and arithmetic representations, a threshold function can be represented in the format of an electric/electronic circuit and also can be represented in a spatial form, by three-dimensional visualization for better understanding the functional properties of threshold functions. The paper discusses a problem-based learning with two main types of problems: synthesis and analysis problems of threshold elements. While the analysis problem is relatively simple, the problem of optimal synthesis is NP-complete, and equivalent to a well-known optimization problem that exists also in linear programming. Using the linear programming for teaching the synthesis of a threshold element is a challenging pedagogical task. The paper describes an approach for solving this task. A number of real-world problems may be formulated and efficiently solved by using the proposed threshold-based approach, for example the problems of event-driven control, fuzzy control, linear optimization, self-regulation. These problems formulate as students’ assignments, and are used in the lesson. These exercises convert a lesson of electronics into an interesting, challengeable and useful educational event. Introduction of the threshold approach into the electronics curriculum enables the students to acquire much deeper understanding of electronic systems.
Fast Fracture in Slow Motion
Authors: Livne Ariel , Cohen Gil , Fineberg Jay
Published: July 2009

We present recent results of fracture experiments in polyacrylamide gels. Polyacrylamide gels are soft polymer materials in which the characteristic sound speeds are on the order of a few meters/sec — thereby slowing down fracture dynamics by 3 orders of magnitude. We first demonstrate the universality of rapid fracture dynamics, comparing dynamics observed in gels with those seen in “classic” brittle materials such as glass. Among the common features are the appearance and form of branching instabilities as well as characteristic attributes of the resulting fracture surface that provide evidence for crack front inertia when translational invariance along the front is broken. We then demonstrate a number wholly new aspects of the fracture process, whose study is only made possible by utilizing the “slow motion” inherent in the fracture of these materials. These include both a new oscillatory instability at about 90% of the Rayleigh wave speed and measurements of the nonlinear zone at the tip of dynamic cracks.
In-Situ Electron Microscopy Testing of 1-D Nanostructures
Authors: Espinosa Horacio D.
Published: July 2009

Over the past decade, there has been a substantial thrust to reduce the size of electronic and electromechanical systems to the nano scale by fabricating devices out of thin films, carbon nanotubes (CNTs) and nanowires (NWs). In these applications, a thorough understanding of material mechanical, electrical and thermal properties as well as device performance and reliability requires the development of novel experimental approaches. In this presentation the design, microfabrication and operation of a MEMS based nanoscale material testing system (n-MTS, see Fig. 1) will be presented. Results obtained from in-situ SEM and TEM tensile testing of NWs and CNTs will be discussed. We will show that TEM imaging is required to properly assess the modulus and strength of multi-walled CNTs (MWCNTs) and demonstrate that the assumption of outer shell failure is not accurate in most cases. We will also discuss a change in failure mode as a function of electron and ion radiation.
Large Deformation Modeling Applied to the Sheet Metal Electromagnetic Forming
Authors: Dumitras C. , Cozminca I.
Published: July 2009

The electromagnetic forming has the advantage of a minimum forming time, but this is a major obstacle in determining the process’s history of the forming workpiece. Both experimental and theoretical known analysis methods for this process give a discret array of data (only for the displacements). One considers it is more adequate to use the finite element method in studying this process. The main advantage of the finite element analysis is given by the fact that it shows the stress and strain fields in a continuous way during the deformation process. Also, it offers a model from which one can predict the final shape of the part and the possible crack zones. One present a compared study of the experimental and the simulated results achieved of the free bulging aluminum specimens by electromagnetic impulses.
Analysis of CMM Accuracy in the Measurement of Roundness
Authors: Gapinski Bartosz , Rucki Miroslaw
Published: July 2009

In the paper, the possibility and accuracy of the roundness measurement with CMM (Coordinate Measuring Machines) has been analyzed. The accuracy of final measurement result is always affected by many factors and conditions of measurement. The following factors underwent discussion: the form deviation and tolerance of measured detail, and the measuring method determined by the number of measuring points, fitting element and uncertainty of CMM. The results of simulations and measurement have proved that the minimal number of measuring points (4 for circle measurement) is not enough. In order to achieve satisfactory results of the roundness measurement, the number of measuring points should be sufficiently increased. On the other hand, the unlimited increase of the points does not improve the measurements results, but extend the time of measurement. The recommendations on the number of measuring points and the required uncertainty of CMM have been presented, too.