bluuebunny/crossref_metadata_2025 huggingface dataset:
Uncertainty Analysis of Wideband Oxygen Sensor Based Strategy for Steady-State Biodiesel Blend Estimation
Authors: Snyder David B. , Adi Gayatri H. , Bunce Michael P. , Satkoski Christopher A. , Shaver Gregory M.
Published: July 2009

Real-time estimation and accommodation is critical for clean and efficient utilization of biodiesel blends in “fuel flexible” diesel engines. This paper utilizes a generalizable, physically-based, and experimentally-verified blend estimation strategy which uses exhaust oxygen sensor measurements coupled with engine control module (ECM) estimates of fuel and air flow to estimate the biodiesel blend fraction. The paper assesses the impact of uncertain variables on the estimation strategy. The strategy is essentially unaffected by biodiesel feedstock variations and, when applied to a Cummins 6.7-liter engine, is not susceptible to significant blend estimation discrepancies in response to expected fuel flow and oxygen sensor errors. However, observed errors in air flow estimates are expected to lead to large blend estimate errors. Use of direct air flow measurement or the use of a dynamic estimator (e.g., Kalman filter) synthesized from the model, the subject matter of future work, is expected to significantly reduce these errors.
Maximizing Wind Turbine Energy Capture via Extremum Seeking Control
Authors: Creaby Justin , Li Yaoyu , Seem John E.
Published: July 2009

Maximizing wind turbine energy capture has become an important issue as more turbines are installed in low wind areas. This paper investigates the application of extremum seeking control (ESC) to maximizing the energy capture of variable speed wind turbine. The optimal control torque and pitch angle are searched via ESC based on the measurement of output power. The advantage is the independency from accurate wind measurement. Simulation has been conducted on FAST for a wind turbine dynamic model, under uniformly steady wind, stair-case wind speed variations, and turbulence wind. The simulation results indicated that the captured power increased by up to 4% over the standard torque control. Anti-windup ESC was then applied to overcome the actuation saturation which may disable the ESC process. Finally, the ESC with high-pass filter input resetting was applied to speed up the transient under abrupt change of wind.
Controlled Synchronization of Mechanical Systems
Authors: Chopra Nikhil , Liu YenChen
Published: July 2009

In this paper we study the problem of synchronization and trajectory tracking in mechanical systems. Exploiting output synchronization results developed previously, a control algorithm is developed to guarantee output synchronization in addition to trajectory tracking in mechanical systems. The classical Slotine-Li adaptive trajectory tracking algorithm is modified to synchronize mechanical systems following a common trajectory. The robustness of the proposed scheme to time delays in communication is also discussed. A numerical example is presented to verify the efficacy of the proposed results.
Modeling Major and Minor Hysteresis Loops in Galfenol-Driven Micro-Positioning Actuators Using a Memory-Based Hysteresis Framework
Authors: Bashash Saeid , Vora Kushan , Jalili Nader , Evans Philip G. , Dapino Marcelo J. , Slaughter Julie
Published: July 2009

This article presents a memory-based hysteresis modeling framework which uses a mathematical mapping technique for accurate prediction of major and minor hysteresis loops in Galfenol-driven actuators. The model is based on three properties of hysteretic materials which have been recently established for piezoelectric actuators. These properties are: targeting of turning points, curve alignment and the wiping-out effect. To describe the anhysteretic behavior of the actuator, we initially separate the nonlinearity of the hysteretic response from the hysteresis looping effect and approximate it with a piecewise exponential function. This function is then utilized in a nonlinear mapping procedure, where it is mapped between consequent turning points recorded in the model’s memory unit. This mapping requires two constant shaping parameters for the ascending and two for the descending trajectories. To assess the performance of the proposed model and for experimental verification, a Galfenol-driven micro-positioning cantilever actuator is utilized. The results indicate that the model is able to precisely predict the response of the actuator for its full-range motion including both major and minor hysteresis loops. The maximum error percentage and the average error between the experiment and the model for a 120 μm stroke are 1.5% and 435 nm, respectively. With using only 14 coefficients, the proposed framework not only offers a precise model, but also a computationally efficient algorithm to quantify the hysteresis response of Galfenol-driven actuators.
Modeling and Forced Vibration Analysis of Rod-Like Solid-State Actuators
Authors: Vora Kushan , Bashash Saeid , Jalili Nader
Published: July 2009

Solid-state smart actuators are widely utilized in a variety of micro and nano-positioning applications. Most of today’s modeling frameworks adopt lumped-parameter representation for system dynamics due to its more straightforward analysis and control. In this article, a distributed-parameters rod-like configuration is considered for free and forced motion analysis of structure. To include the effects of widely-used flexural mechanisms, a mass-spring-damper boundary condition is considered for the system. Moreover, the effect of electromechanical actuation is included as a concentrated force at the boundary. The problem is then divided into two parts: first part deals with free motion analysis of system to obtain eigenvalues and eigenfunctions using the expansion theorem and a standard eigenvalue problem procedure. The effects of different boundary mass and spring values on the natural frequencies and mode shapes are demonstrated, which indicate their significant contribution to system dynamical properties. In the second part, forced motion analysis of system and its state-space conversion tools are presented. It is shown that distributed-parameters modeling is inevitable when precision high frequency motions are demanded. This can enhance control bandwidth and performance of rod-like solid-state actuators such as piezoelectric and magnetostrictive positioners with moving to next generation digital signal processing systems which enable ultrahigh-frequency sampling rates.
Parts Entropy, Symmetry and the Difficulty of Self-Replication
Authors: Chirikjian Gregory S.
Published: July 2009

A self-replicating robot (SRR) is one that can identify and assemble spare parts into an exact functional copy of itself. An SRR that is able to identify and pick up parts that are randomly scattered in an environment without prior knowledge of their location would be more robust than one that requires parts to be positioned at exactly known locations. Therefore, the degree of disorder in the environment that an SRR is able to handle is in some sense a measure of how “powerful” it is. The entropy of the ensemble of all possible configurations of parts quantifies this concept. In this paper, various issues associated with computing the entropy of ensembles of configurations of parts are explored. The effect of part symmetries is analyzed. It is shown that both the design of parts and the evaluation of an SRR’s functionality can be influenced by the knowledge of part entropies.
Resilient Self-Reproducing Systems
Authors: Menezes Amor A. , Kabamba Pierre T.
Published: July 2009

This paper is motivated by the need to minimize the payload mass required to establish an extraterrestrial robotic colony. One approach for this minimization is to deploy a colony consisting of individual robots capable of self-reproducing. An important consideration once such a colony is established is its resiliency to large-scale environment or state variations. Previous approaches to learning and adaptation in self-reconfigurable robots have utilized reinforcement learning, cellular automata, and distributed control schemes to achieve robust handling of failure modes at the modular level. This work considers self-reconfigurability at the system level, where each constituent robot is endowed with a self-reproductive capacity. Rather than focus on individual dynamics, the hypothesis is that resiliency in a collective may be achieved if: 1) individual robots are free to explore all options in their decision space, including self-reproduction, and 2) they dwell preferentially on the most favorable options. Through simulations, we demonstrate that a colony operating in accordance with this hypothesis is able to adapt to changes in the external environment, respond rapidly to applied disturbances and disruptions to the internal system states, and operate in the presence of uncertainty.
Bond Graph Modeling and Analysis of Active Differential Kinematics
Authors: Deur Josˇko , Hancock Matthew , Assadian Francis
Published: July 2009

This paper describes the kinematic structures of Active Limited Slip Differential (ALSD) and different concepts of Torque Vectoring Differentials (TVD) (superposition clutch concept, stationary clutch concept, and 4WD concept). The bond graph method is used to derive the models of ALSD/TVD kinematics. Based on the developed models, a comparative analysis of active differential operating modes and performance is conducted.
Robust Control for Multiple Time Delay Systems With Delay–Decouplability Concept
Authors: Turkoglu Kamran , Olgac Nejat
Published: July 2009

We consider linear time-invariant minimum phase MIMO plants in this paper, with multiple control delays. The delays appear at several components of the state. Deployment of delay decoupling control (DDC) creates a characteristic equation which facilitates the assessment of stability in each of the delays independently from each other. When, however, some system parameters are uncertain, the characteristic equation seems to entail truly coupled delays, which forces the stability assessment to an N-P hard complexity class problem. We show that this assessment can be very efficient using the Cluster Treatment of Characteristic Roots (CTCR) paradigm. The main contribution of the study is for a certain class of structures, if the feedback control forms with independent delays on separate feedback channels decouplability may still hold, and the robustness analysis becomes efficient. This result is demonstrated for 2-input, 2-output system, and it is claimed that the findings are scalable to higher dimensional dynamics. Example case study of a cart-pendulum system is treated.
Numerical Evidence for Cutoffs in Chaotic Microfluidic Mixing
Authors: Liang Tzu-Chen , West Matthew
Published: July 2009

Chaotic mixing strategies produce high mixing rates in microfluidic channels and other applications. In prior numerical and experimental work the variance of a tracer field in a chaotic mixer has been observed to decay rapidly after an initial slower transient. We relate this to the cutoff phenomenon observed in finite Markov chains and provide numerical evidence to suggest that chaotic mixing indeed exhibits cutoff. We provide results for a herringbone passive microfluidic mixer and the Standard Map.
Co-Regulation of Calcium and Delayed Rectifier Currents Maintains Neuronal Output in a Model of a Crustacean Cardiac Motor Neuron
Authors: Ball John M. , Franklin Clarence C. , Schulz David J. , Nair Satish S.
Published: July 2009

Homeostatic processes are widespread throughout all living systems, and the nervous system is no exception. Individual neurons as well as neuronal networks must maintain levels of excitability and connectivity to ensure that consistent functional output is achieved. Possible mechanisms for maintaining functional output using co-regulation of channel conductances is studied for a motor neuron, using a computational model. The results are both consistent with and extend the biological observations.
Single Vortex Streets on the Sphere
Authors: Chamoun George C. , Kanso Eva , Newton Paul K.
Published: July 2009

We study arrangements of point vortices on a sphere in the form of a single von Ka´rma´n vortex street, with and without the addition of pole vortices using the configuration matrix approach recently introduced by (1) and (2) on the sphere. We derive the general form of the von Ka´rma´n matrix thereby obtaining all possible vortex strengths for which the configuration rotates rigidly, perpendicular to the axis of rotation of the sphere. The distribution of normalized singular values of the von Ka´rma´n matrices allows us to calculate their Shannon entropy (as a function of the vortex street parameters), which we interpret as a scalar measure of ‘disorder’ and robustness of the vortex street. We also study the streamline topologies associated with the vortex street and identify a number of distinct topologies which support a jet-stream passing through the street capable of transporting particles globally.
A Biologically-Inspired Dynamic Legged Locomotion With a Modular Reconfigurable Robot
Authors: Sastra Jimmy , Bernal Heredia Willy Giovanni , Clark Jonathan , Yim Mark
Published: July 2009

Reconfigurable Modular robots can adapt their morphologies and their gaits for locomotion through different environments, whether like a snake for moving through constrained spaces or in a wheel-like shape for efficient and fast rolling on flat terrain. This paper proposes a new, scalable biologically-inspired legged style of locomotion for this class of robots. Passively compliant leg attachments are utilized to achieve a dynamic running gait using body articulation. A dynamic simulation as well as experimental data showing that we have achieved stable dynamic locomotion is presented. Although the robot design and control strategy are, in principle, scalable to any number of leg pairs, results are given for a hexapedal robot configuration. This prototype represents the first example of dynamic legged locomotion driven only by body articulation.
Regulation of Fear by Amygdala Intercalated Cells in a Network Model of Fear Acquisition and Extinction
Authors: Li Guoshi , Quirk Gregory J. , Nair Satish S.
Published: July 2009

A computational model of the fear circuit was developed to study regulation of fear by amygdala intercalated (ITC) neurons within the amygdala. A new biophysical model of an ITC neuron was developed first to capture its bistable behavior caused by an unusual slowly deinactivating current. An existing lateral amygdala network model was then extended into an overall fear circuit by adding ITC neurons, together with additional amygdaloid structures. Using a biophysical Hebbian learning rule for plastic synapses, the model successfully simulated the amygdala responses during acquisition, extinction, and recall of extinction in auditory fear conditioning. Results showed that fear could be regulated by the bistability of ITC neurons. The model also suggested additional sites for the storage fear and extinction memories.
Control of Mobile Sensor Networks: A State-of-the-Art Review
Authors: Hedrick J. Karl , Basso Brandon , Love Joshua , Girard Anouck R. , Klesh Andrew T.
Published: July 2009

This paper presents a state-of-the-art survey in the broad area of Mobile Sensor Networks (MSNs). There is currently a great deal of interest in having autonomous vehicles carrying sensors and communication devices that can conduct ISR (intelligence, surveillance and reconnaissance) operations. Although this paper will discuss issues common to mobile sensor networks, the applications will generally be associated with autonomous vehicles. Areas that are addressed are: 1. Mission definition languages that allow the human to compose a mission defined in terms of tasks; 2. Communication issues including hardware, software, and network connectivity; 3. Task allocation among the assets generally by a market-based approach; 4. Path planning for individual agents; and 5. Platform motion control using autopilots with and without GPS signals and including collision avoidance.
Nonlinear Dynamics and Its Applications in Micro- and Nanoresonators
Authors: Rhoads Jeffrey F. , Shaw Steven W. , Turner Kimberly L.
Published: July 2009

This review provides a summary of the work completed to date on the nonlinear dynamics of resonant micro- and nanoelectromechanical systems (MEMS/NEMS). This research area, which has been active for approximately a decade, involves the study of nonlinear behaviors arising in small scale, vibratory, mechanical devices that are typically integrated with electronics for use in signal processing, actuation, and sensing applications. The inherent nature of these devices, which includes low damping, desired resonant operation, and the presence of nonlinear potential fields, sets an ideal stage for the appearance of nonlinear behavior, and this allows engineers to beneficially leverage nonlinear dynamics in the course of device design. This work provides an overview of the fundamental research on nonlinear behaviors arising in micro/nanoresonators, including direct and parametric resonances, parametric amplification, impacts, selfexcited oscillations, and collective behaviors, such as localization and synchronization, which arise in coupled resonator arrays. In addition, the work describes the active exploitation of nonlinear dynamics in the development of resonant mass sensors, inertial sensors, and electromechanical signal processing systems. The paper closes with some brief remarks about important ongoing developments in the field.
A Review of the Exoskeleton and Human Augmentation Technology
Authors: Kazerooni H.
Published: July 2009

This paper is written for the plenary talk of 2008 ASME Dynamic Systems and Control Conference in Ann Arbor Michigan and gives an overview of the exoskeleton technology and human augmentation. Human-Robot integration outlines the future of robotics. The technology associated with exoskeleton systems and human power augmentation can be divided into lower extremity exoskeletons and upper extremity exoskeletons. The reason for this was two-fold; firstly, one could envision a great many applications for either a stand-alone lower or upper extremity exoskeleton in the immediate future. Secondly, and more importantly, the reason for the division is that it is unclear if an integrated upper extremity-lower extremity exoskeleton is a scientifically-valid concept in logistical operations (i.e., lifting and carrying heavy objects).
Eigenvalues and Sensitivity Analysis for a Model of HIV-1 Pathogenesis With an Intracellular Delay
Authors: Yi Sun , Nelson Patrick W. , Ulsoy A. Galip
Published: July 2009

During the past decade significant research has been aimed at better understanding for human immunodeficiency virus type 1 (HIV-1), and the use of mathematical modeling to interpret experimental results has made a significant contribution. However, time-delays, which play a critical role in various biological models, are still not amenable to many traditional analysis methods. In this paper, we apply a recently developed approach using the Lambert W function to handle the time delay in a HIV-1 pathogenesis dynamic model. Dominant eigenvalues in the infinite eigenspectrum of these time-delay systems are obtained and used to understand the effects of the parameters of the model on the immune system. Also, the result is extended to analyze the sensitivity of the eigenvalues with respect to the parameters in the HIV-1 model. The research makes it possible to know which parameters are more influential than others, and the obtained information is used to investigate the HIV-1 dynamic system analytically.
In-Process Surface Normal Estimation for Raster Scanned Point Cloud Data
Authors: Srivatsan Vijay , Katz Reuven
Published: July 2009

A method for in-process surface normal estimation from point cloud data is presented. The method enables surface normal estimation immediately after coordinates of points are measured. Such an approach allows in-process computational registration, used for collision and occlusion avoidance during dimensional inspection with high-precision point-based range sensors. The most commonly used sensor path for inspection with high-precision point-based range sensors is a raster scan path. A novel neighborhood identification approach for raster scanned point cloud data is presented. Quadratic polynomials are used to model the local geometry of the surface, from which the surface normal is estimated for the point. Implementation of the method through simulations and on a real part shows the normal estimation error to be within 0.1°.
Effect of Directionality of Grinding Marks on Friction and Formation of Transfer Layer
Authors: Menezes Pradeep L. , Kishore  , Kailas Satish V.
Published: July 2009

Surface texture influences friction and transfer layer formation during sliding. In the present investigation, basic studies were conducted using inclined pin-on-plate sliding tester to understand the effect of directionality of surface grinding marks of hard material on friction and transfer layer formation during sliding against soft materials. 080 M40 steel plates were ground to attain different surface roughness with unidirectional grinding marks. Then pins made of soft materials such as pure Al, pure Mg and Al-Mg alloy were slid against the prepared steel plates. Grinding angle (i.e., the angle between direction of sliding and grinding marks) was varied between 0° and 90° in the tests. Experiments were conducted under both dry and lubricated conditions on each plate in ambient environment. It was observed that the transfer layer formation and the coefficient of friction, which has two components — adhesion and plowing — depend primarily on the directionality of grinding marks of the harder mating surface, and independent of surface roughness of the harder mating surface. For the case of pure Mg, stick-slip phenomenon was observed under dry condition for all grinding angles and it was absent upto 20° grinding angles under lubricated condition. However, for the case of Al, it was observed only under lubricated conditions for angles exceeding 20°. As regards the alloy, namely, Al-Mg alloy, it was absent in both conditions. For the case of pure Mg and Al, it was observed that the amplitude of stick-slip motion primarily depends on plowing component of friction. The grinding angle effect on coefficient of friction was attributed to the variation of plowing component of friction with grinding angle.
A Finite Element Approach Derived From the Simplified Variational Principle
Authors: Yahalom Asher
Published: July 2009

In previous papers [1–4] we have described how by minimizing the fluid action numerically one can obtain a solution of the fluid steady state equations. The action which was used was the four function action of Seliger & Whitham [5]. In a recent paper [6] we describe how one can improve upon previous art by reducing the number of variables in the action. Three independent functions variational formalism for stationary and non-stationary barotropic flows is introduced. This is less than the four variables which appear in the standard equations of fluid dynamics which are the velocity field ν⃗ and the density ρ. In this paper we will discuss a possible finite element approach related to the usage of the new action principles as basis for a CFD algorithms.
Network Methods in Engineering
Authors: Shai Offer , Preiss Kenneth
Published: July 2009

This paper reviews the main idea underlying the use of network graph theory for analysis or for design of physical engineered systems. A physical engineered system is a system built from physical components, as compared with a system built only from symbols or software. The term includes structures, mechanisms, electric circuits and more. Different engineered systems may be represented as the same graph, or as graphs that show a known mathematical relationship between them. We then have a single mathematical representation that is applicable to more than one engineered system. The properties of the graph, as known from graph theory, are applicable to all the engineered systems in domains that match that graph. The graph can be regarded as a generalized representation suitable for various engineered systems. Engineering theory is commonly divided into domains, solid mechanics, mechanisms, fluid mechanics, heat transfer, and more. When dealing with engineered systems using the language and mathematical formality of graph theory such divisions become unnecessary. Network graph theory can apply similar or even identical theory to many engineering domains.
The Effect of Laser Surface Texturing on Soft Elasto-Hydrodynamic Lubrication Considering Non-Linear Elasticity
Authors: Shinkarenko Alexey , Kligerman Yuri , Etsion Izhak
Published: July 2009

A non-linear theoretical model is presented to study the effect of laser surface texturing (LST) on the load carrying capacity in soft elasto-hydrodynamic lubrication (SEHL). Both geometrical and physical non-linearity of the elastomer is considered by using a logarithmic strain and the Mooney-Rivlin constitutive law, respectively. The results of the present non-linear model are compared with those of a previous linear one over a wide range of operating conditions. It is found that the two models predict the same optimum LST parameters for maximum load capacity but the non-linear model gives load capacity that is up to 10% lower than that obtained from the linear model.
Models of Potential and Wear Particles in a Spherical Contact
Authors: Salib Jiries , Kligerman Yuri , Etsion Izhak
Published: July 2009

The main goal of the current study is a numerical prediction of adhesive wear volume in a spherical contact. The contact consists of a deformable sphere and a rigid flat subjected to combined normal and tangential loading under full stick contact condition. Following the completion of the normal loading a tangential load is applied gradually leading to a decrease in the stiffness of the contact and eventually to sliding inception. Due to the full stick contact condition the sliding inception can occur on a certain surface beneath the contact interface. The entire volume contained between this incipient sliding surface and the contact interface defines a potential wear particle. Further increase of the tangential loading will eventually result in a detachment of a certain actual wear particle from the sphere. The detachment surface, which differs from the incipient sliding surface, occurs where the sphere material has failed due to reaching the ultimate shear or tensile strain. The volume contained between this detachment surface and the contact interface forms the actual wear particle that adheres to the moving flat and results in material transfer. Empirical expressions for the volumes of the potential and actual wear particles are developed showing their dependency on material properties and the normal preload.
H-Infinity Controlled Actuators in Automotive Active Suspension System
Authors: Kruczek Alesˇ , Strˇi´brsky´ Antoni´n , Hyniova´ Katerˇina , Hlinovsky´ Martin
Published: July 2009

In this paper active suspension with linear electric motor has been designed. The active suspension is often hardly rejected for its big energy consumption. This contribution deals with direct real-time energy control in suspension system. The linear electric motor is used as an actuator. This motor can in specific situation generate the energy for next use. The H-infinity controller has been developed to improve car behavior, in particular passenger comfort and car stability. The second objective of the controller is to control energy distribution. Our submission is mainly focused on vehicle suspension, but it can be generalized to any kind of active suspension.
Effect of Multivariable Dead Times on the Properties of the Quadruple-Tank Process
Authors: Palmor Zalman J. , Shneiderman Dmitry
Published: July 2009

The well known laboratory Quadruple-Tank Process (QTP) has been introduced in the laboratories of many schools around the world as it is ideally suited to illustrate concepts in multivariable control. In this paper the QTP is extended to include independent multivariable dead times (DTs) and their effects on the properties of the QTP are studied. DTs are very common in many various processes and make the control of the QTP more interesting and challenging. The addition of DTs may introduce infinite, finite or not any number of non-minimum-phase (NMP) zeros. As shown in the paper it depends on a particular combination of the multivariable DTs. The conditions for each case are stated and the location and behavior of the zeros closest to the imaginary axis due to the DTs are specified. Other properties of the QTP with DTs as the output real NMP zero directions and the decentralized integral controllability of the process are discussed too. Also, a novel laboratory QTP with DTs is described.
A Rough-Cut Cost Estimation in a Finite-Capacity Stochastic Environment Based on Forced Idle Time Prediction
Authors: Eklin Mark , Arzi Yohanan , Shtub Avraham
Published: July 2009

In recent years several researchers suggested cost estimation models that consider the limited capacity of the shop. In these studies, the stochastic nature of the shop floor is modeled by a time-consuming simulation. This paper proposes five alternative rough-cut cost estimation methods that can replace the simulation. Three of five methods based on forced idle time prediction. The study compares the cost estimations derived from these methods. A cost estimation method, based on the forced idle time of the bottleneck workstation, was found to be outperform the others. As the best method, the bottleneck-based method was compared to the actual order’s cost and was found as a replacement to simulation.
Control Organization: Survey and Application
Authors: Rusnak Ilan
Published: July 2009

The issue of the organization of control and feedback can be subdivided into several subjects: i) Selection of performance objectives; ii) The control algorithms; iii) Selection of measured and manipulated variables; and iv) Feedback organization. In previous publication [1] partial survey of the issues above and a terminology for feedback and control organization has been presented, that is, not all issues and not all relevant disciplines have been covered. Namely, motion control and servo-regulator applications have been covered; however, aircraft control, missile autopilots and process control have been barely covered. The issues of: (i) Selection of measured variables (location of sensors) and manipulated variables (location of actuators) called as well as Input-Output Selection (IO); (ii) Control Structure Design (CSD); and (iii) Control Configuration selection (CC); had not been covered and are presented here. These issues are strictly proper sub-issues of the Control and Feedback organization problem. This paper extends the survey to additional disciplines and subjects. Thus this paper can be considered as part II and supplement of [1]. Using the definitions the problem of Control and Feedback Organization (CFO) is defined over the set theory within the well-established functional analysis and optimal control theories. The optimal control-feedback organization problem and the optimal simultaneous design of the system and feedback configuration problem are presented as open issues. This demonstrates the usefulness of the existence of a proper terminology and theory of the control-feedback organization problem and its extension and connection to design of sensors and actuators location. As an example the architecture generating property of the LQR metric is used to derive advanced high performance architecture for motion control applications.
Notes on the Kinematics of an Octopus’s Arm
Authors: Levinson Y. , Segev R. , Shapiro A.
Published: July 2009

In a study of the kinematics of an Octopus’s arm from the robotics point of view, we consider two models: a discrete model and a continuum model. Both models represent control of the curve in space defined by the centerline of the arm and the position of the suction elements of the arm relative to the centerline. The two models also represent the control of the arm by means of three groups of muscles: the longitudinal, transverse and helicoidal groups. Another feature of the kinematics exhibited by the two models is the use of incompressibility in the control of the arm. In the discrete model, the arm is represented as a sequence of parallel mechanisms. Each mechanism in the sequence consists of two parallel platforms of variable dimensions so that the resulting sequence of platforms represents the various cross sections of the arm. The continuum rod model that we use allows linear in-plane deformation of the cross-section and assumes that cross-sections remain perpendicular to the axis of the rod.
An Assembly Microfactory for Hybrid Microproducts
Authors: Santochi Marco , Porta Marcello , Fantoni Gualtiero
Published: July 2009

The microfactory seems to be one of the most promising approaches for reducing the assembly cost of hybrid microproducts. The microfactory is a miniaturized assembly system with a reduced consumption of space and energy compared to conventional assembly systems. The assembly microfactory includes the same devices of a traditional assembly system: handling, joining, monitoring devices and also proper strategies to assure a correct assembly. The assembly microfactory here presented consists of various prototypes and commercial handling devices integrated in the same assembly environment. The complete system is able to automatically perform different assembly tasks. As a bench test for evaluating the microfactory performance, a product made of several microcomponents of different materials and shapes has been designed. The operations necessary for its correct assembly are: pick and place of parts with various shapes, peg-in-hole of microcylinders with small clearance, alignment and positioning of microparts. The main goal of the developed microfactory is to demonstrate the reliability and the feasibility of the tested devices in complex microhandling tasks and their capability to be simply integrated in a microassembly environment. Another purpose is to show the feasibility and the flexibility of the adopted assembly strategy in the micro domain. Several different transporting and grasping devices find application in the assembly system. Two innovative electrostatic feeders and an electrostatic sorter are used to sort, transport and position microspheres, microcylinders and microgears with dimension of few hundreds microns. Four different types of grippers (a mechanical, an electrostatic, an adhesive and a pneumatic one) supported by a 3 DOFs commercial micropositioner have been used to execute peg-in-hole of microcylinders with a diameter of 500 μm and pick and place of microspheres with a diameter in the range of 800–1100 μm.
A New Generation of Tools for the Design of Tall Buildings Subjected to Wind Loads
Authors: Simiu Emil , Gabbai Rene D.
Published: July 2009

Current approaches to the estimation of wind-induced wind effects on tall buildings are based largely on 1970s and 1980s technology, and were shown to result in some cases in errors of up to 40%. Improvements are needed in: (i) the description of direction-dependent aerodynamics; (ii) the description of the direction-dependent extreme wind climate; (iii) the estimation of inertial wind effects induced by fluctuating aerodynamic forces acting on the entire building envelope; (iv) the estimation of uncertainties inherent in the wind effects; and (v) the use of applied wind forces, calculated inertial forces, and uncertainty estimates, to obtain via influence coefficients accurate and risk-consistent estimates of wind-induced internal forces or demand-to-capacity ratios for any individual structural member. Methods used in current wind engineering practice are especially deficient when the distribution of the wind loads over the building surface and their effects at levels other than the building base are not known, as is the case when measurements are obtained by the High-Frequency Force Balance method, particularly in the presence of aerodynamic interference effects due to neighboring buildings. The paper describes a procedure that makes it possible to estimate wind-induced internal forces and demand-to-capacity ratios in any individual member by: developing aerodynamic and wind climatological data sets, as well as aerodynamic/climatological directional interaction models; significantly improving the quality of the design via rigorous structural engineering methods made possible by modern computational resources; and properly accounting for knowledge uncertainties. The paper covers estimates of wind effects required for allowable stress design, wherein knowledge uncertainties pertaining to the parameters that determine the wind loading are not considered, as well as estimates required for strength design, in which these uncertainties need to be accounted for explicitly.
Dynamic Analysis of a Parallel Pick-and-Place Robot With Flexible Links
Authors: Li Haihong , Yang Zhiyong
Published: July 2009

The dynamic modeling and analysis of a 2-DOF translational parallel robot for high-speed pick-and-place operation was presented. Considering the flexibility of all links, the governing equation of motion of a flexible link is formulated in the floating frame of reference using Euler-Lagrange method. A kineto-elasto dynamic model of the system is achieved, ready for modal analysis. Simulation in FEM software showed the similar modes with above computational result in typical location and rotation. The dynamic experiment presented the dominant modes and proved the theoretical analysis and simulation. The Diamond robot used in Lithium-ion battery sorting was taken as an example to demonstrate how to finish above studies. The result shows that the mechanism has good dynamic performance. The work is available for all parallel robots with flexible links.
Experimental Determination of Optimal Speeds for Alloy Steels in Plane Turning
Authors: Srikanth T. , Kamala V.
Published: July 2009

In machining, speeds play vital role. The operator should know exactly the speed at which machining should be performed to get the required surface finish. In this paper, an attempt is made to determine the optimal cutting speed for machining of alloy steels. Three work piece materials having different hardness are taken and machined using a round nose tool with a coated tip. The tool dynamometer is attached to the tool post for force measurement. Turning operation on the work piece is performed on lathe at four different speeds, keeping the feed and depth of cut constant. Cutting forces acting on the tool, temperature at the tool and material interface are recorded. Power consumed being determined by a wattmeter and surface roughness values are measured. The same procedure is repeated for the other two work-pieces materials and optimal speeds for machining are determined for the three specimens. The results obtained are compared with the theoretical values and found to be very close.
A Survey of Autonomous Control Algorithms by Means of Adapted Vehicle Routing Problems
Authors: Scholz-Reiter Bernd , Rekersbrink Henning , Wenning Bernd-Ludwig , Makuschewitz Thomas
Published: July 2009

The German Collaborative Research Centre 637 “Autonomous Cooperating Logistic Processes – A Paradigm Shift and its Limitations”, develops, among other things, autonomous routing algorithms for transport networks. The discussed algorithm is designed to match goods and vehicles and to continuously make route decisions within a dynamic transport network. Here, each object makes its own decisions. It is called Distributed Logistics Routing Protocol – DLRP. Because of obvious similarities to the Vehicle Routing Problem (VRP), one question arises for both practitioners and researchers: How efficient is this protocol compared to traditional, established algorithms or in comparison to the optimal solution? This article tries to answer this question, which appears simple on the first and challenging on the second view.
SEN Analysis of Stratified Hot Water Heat Stores With Respect to Axial Position and Number of Charging-Discharging Equipments
Authors: Panthalookaran Varghese
Published: July 2009

SEN analysis [Solar Energy, 2007, Vol. 81, pp. 1043–1054] is a robust characterization method for stratified thermal energy stores (TES). It integrates the concerns of the First and Second Law of Thermodynamics into single efficiency index. The First Law concern is incorporated into the definition of SEN efficiency index through energy response factor (ER) and the Second Law concern through entropy generation ratio (REG). SEN analysis thus estimates the ability of a TES to store energy and exergy. In the current paper SEN analysis is utilized to characterize hot water heat stores (HWHS) with respect to the axial position and number of charging/discharging equipments they possess. Diffusers or flow-guides are used as charging-discharging equipments in view of reducing turbulent mixing within the HWHS, especially in the entrance and exit ports. For HWHS charging-discharging equipments are commonly positioned in the top-most and bottom-most regions of the HWHS in order to avoid development of dead volume, i.e., volume that does not take part in the charging-discharging process. Axially placed conical diffusers are observed to circumvent the issue of dead volumes. However, the effect of their axial position on the entropy generation is not yet studied. Further, one may use intermediate charging-discharging equipment in association with the original pair in order to feed or withdraw the working fluid into/from the HWHS at different heights. This paper provides a detailed analysis of the position and number of axially placed conical diffusers with zero diffuser angles inside a cylindrical HWHS. The thermal field information obtained from a computational fluid dynamic (CFD) analysis is subjected to the SEN analysis to achieve required design insights.
Kinematic and Dynamic Simulations for the Design of iCub Upper-Body Structure
Authors: Nava R. Nestor E. , Metta Giorgio , Sandini Giulio , Tikhanoff Vadim
Published: July 2009

In this paper we present kinematic and dynamic simulations of the humanoid robot iCub in operation. ICub is the result of RobotCub, an EU-funded project, which aims at developing an open-source humanoid platform by following an original research line in synthetic cognition. Workspace analysis and singular positions have been computed for the structure of the upper-body sub-systems. Simulations validated the manipulation performance of iCub under dynamic conditions. Actuating torques have been computed on the joint structure. The analysis of the results may suggest that further design improvements are possible for iCub.
An Instrument That Simultaneously Measures Spatiotemporal Gait Parameters and Ground Reaction Forces of Locomoting Rats
Authors: Tasch U. , Moubarak P. , Tang W. , Zhu L. , Lovering R. M. , Roche J. , Bloch R. J.
Published: July 2009

We describe an instrument that assesses two features of the gait of rats, spatiotemporal paw movement variables (SPMV) and ground reaction forces (GRF) in the vertical direction. The GRF and the SPMV variables are measured electrically by eight single axis load-cells that support two floor plates. We can derive four gait parameters from the SPMV and GRF measured by the instrument: the stride length of individual limbs, the maximum and mean vertical ground forces, and the intensity of the vibrations created by each paw during locomotion. Measurements of the vertical GRF show errors of less than 3.5%; errors in the determination of the paw positions, used to derive stride lengths, are less than 9 mm. Here we report the stride length, maximum and mean GRF values, and the intensity of the floor vibrations of healthy adult mature rats. Our instrument is capable of evaluating changes in these gait parameters in rat models of injury and disease.
Framework for Flaw Detection: Application to Dynamic Crack Detection in Flat Membranes
Authors: Rabinovich Daniel , Givoli Dan , Vigdergauz Shmuel
Published: July 2009

A computational framework is developed for the detection of flaws in flexible structures. The framework is based on posing the detection problem as an inverse problem, which requires the solution of many forward problems. Each forward problem is associated with a known flaw; an appropriate cost functional evaluates the quality of each candidate flaw based on the solution of the corresponding forward problem. On the higher level, the inverse problem is solved by a global optimization algorithm. The performance of the computational framework is evaluated by considering the detectability of various types of flaws. In the present context detectability is defined by introducing a measure of the distance between the sought flaw and trial flaws in the space of the parameters characterizing the configuration of the flaw. The framework is applied to crack detection in flat membranes subjected to time-harmonic and transient excitations. The detectability of cracks is compared for these two cases.
3D CFD Modeling and Experimental Validation for Slurry Flow Through Pipe Bend
Authors: Kumar Arvind , Kaushal D. R. , Kumar Umesh
Published: July 2009

Bends are integral part of any slurry pipeline system and are prone to excessive wear. Therefore, a detailed knowledge of the flow characteristics in the bends will enable us to identify the causes of excessive wear which in turn may help in developing remedial steps to control the excessive wear. In the present study, experimental data are collected in a 90 degree horizontal pipe bend having bend radius of 148 mm situated in a pilot plant test loop with pipe diameter of 53 mm. The experiments are performed at volumetric concentration of 16.28% of silica sand having mean particle diameter of 448.5 micron. The flow velocity was varied from 1.78 to 3.56 m/s. Separation chambers are provided at each pressure tap for interface separation of slurry and manometric fluid, water being the intermediate fluid. For better accuracy, pressure drop along the pipeline is measured by an inclined manometer. Electromagnetic flow meter is used for the measurement of slurry discharge. It is observed that pressure drop along the pipe bend increases with flow velocity. The experimental data collected in the present study have been compared with the three-dimensional computational fluid dynamics (CFD) modeling, using Eulerian two-phase model and commercial CFD package FLUENT 6.2. Eulerian model expands the definition of continuum assumption to the dispersed phase and treats both continuous and dispersed phases separately as two phases. Both phases are linked using the drag force in the momentum equation. The standard k-epsilon model is used to treat turbulence phenomena in both the phases. The granular theory for the liquid–solid flow of the Eulerian model is introduced. Gambit software is used for the development of mesh. It is observed that CFD modeling gives fairly accurate results for almost all the pressure drop data considered in the present study. CFD modeling results for concentration and velocity profiles for collected experimental data have also been presented.
Processing-Structure-Property Relationships in Hierarchically-Structured Polymer Composites for Multifunctional Structures
Authors: Bruck Hugh A.
Published: July 2009

This research focuses on elucidating on the processing-structure-property relationship in hierarchically-structured polymer composites that are being developed for multifunctional structures. This is accomplished through characterization of the transition in mechanical behavior that occurs across length scales and compositions by: (a) development of model hierarchically-structured composite materials using a combination of model nanoscale and microscale ingredients (carbon nanofibers (CNFs) and carbon microfibers (CMFs)) reinforcing a High Impact Polystyrene (HIPS) thermoplastic polymer that can be extruded or solvent processed, (b) characterization and modeling of the transition compositions in the polymer nanocomposites through melt rheology, and (c) the effect of the CNF on the dynamic compressive behavior of CMF-reinforced polymer composites.