bluuebunny/crossref_metadata_2025 huggingface dataset:
A Multiperiod Breakeven Analysis
Authors: Moore Giora
Published: September 2010

This paper presents a breakeven analysis in a multi‐periodframework. The purpose of the model construction offered here is to modify the traditional one‐period breakeven analysis and to broaden the scope of its application in management decision making. The main findings are that an increase in the corporate tax rate, the cost of capital or the annual inflation rate will require a higher annual breakeven output An increase in the capital cost allowance rate or in the time period of using the asset will require a lower annual breakeven output. The model presents a theoretical integration of breakeven analysis and capital budgeting. The applications of the multiperiod breakeven analysis are illustrated in numerical examples, in accordance with the tax laws in Canada.

Cette étude présente une analyse du point mort effectuée dans un cadre à périodes multiples. Le but de ce modelè est de modifier l'analyse traditionnelle du point mort à période unique et d'élargir l'étendue de son application dans la prise de décision. Les principaux résultats de cette étude indiquent qu'une augmentation du taux d'imposition des sociétés, du coǔt du capital ou du taux annuel d'inflation exigera un point mort annuel plus élevé. Une augmentation du taux de l'allocation du coǔt en capital ou dans la période d'utilisation d'un élément d'actif exigera un point mort annuel moins éleve. Le modèle présente une intégration théorique de l'analyse du oint mort quant aux dépenses en capital. Les applications d'une analyse du point mort à périodes multiples sont illustrés à l'aide d'exemples numériques, conformément aux lois fiscales du Canada.
La gestion du changement technologique: organisationnelle?
Authors: Alsène Éric , Denis Hélène
Published: September 2010

More and more managers recognize today that the introduction of new operation technologies into the enterprise needs to be managed not only from a technical standpoint but also from an organizational one. Therefore this study aims at establishing whether, and to which extent, the management of technological changes in three firms located in Quebec (an industrial enterprise in process production, an industrial enterprise in assembly production, and a service enterprise) has actually taken the organization design into account. The new operation technologies concerned are: a computer process control system, some automatic assembly machines, a manufacturing resource planning (MRP II) system, and some automatic service equipments.

De plus en plus de managers reconnaissent aujourd'hui que l'introduction de nouvelles technologies d'opération au sein de l'entreprise nécessite une gestion non seulement technique, mais également organisationnelle. La recherche tente en conséquence d'établir si, et dans quelle mesure, la prise en compte de l'organisation a effectivement été une pratique de gestion du changement technologique dans trois entreprises localisées au Québec (une entreprise industrielle de process, une entreprise industrielle d'assemblage, une entreprise de services), ces entreprises s'étant dotées récemment de nouvelles technologies d'opération (système informatisé de contrôle de procédé, machines automatiques d'assemblage, système MRP II de planification et de contrôle de la production, appareils automatiques de service).
Linfluence du pays d'origine sur l‘évaluation de produits suscitant différents niveaux d'implication: Une approche multi‐attributs
Authors: Ahmed Sadrudin A. , D'Astous Alain
Published: September 2010

Dans un contexte de concurrence globale, les firmes de pays industrialisés ont des choix difficiles à faire quant au lieu de fabrication de leurs produits, aux noms de marque à utiliser, aux prix et aux programmes de garantie de satisfaction à offrir à leurs clients. Cette étude examine l'appréciation que des consommateurs font de profils d'analyse conjointe pour trois catégories de produits: automobiles, magnétoscopes et T‐shirts. Les profils diffèrent au niveau du pays d'origine (Canada, un second pays industrialisé prestigieux et un pays de mauvaise réputation), des noms de marque, des prix et des programmes de garantie de satisfaction. On a interrogé 179 consommateurs Canadiens de langue française, sélectionnés de façon probabiliste. Les résultats indiquent que l'effet du prix sur la valeur perçue d'un achat n'est pas très important. Le nom de marque est l'indice le plus important pour les automobiles, la garantie pour les magnétoscopes et le lieu de fabrication pour les T‐shirts. Il semble que la valeur informative du pays d'origine varie selon le niveau d'implication de la catégorie de produit et la présence d'autres indices d'information. Des implications managériales concernant des aspects de marketing international sont tirées des résultats de l'étude et discutées.

In a time of increasing global competition, firms from industrialized countries are faced with difficult choices concerning where they should locate their manufacturing facilities, what brand names to use, what price to charge, and what level of satisfaction guarantee to provide their customers. This study examines consumer evaluations of conjoint profiles of automobiles, VCRs and T‐shirts, manufactured in Canada (home country), a second prestigious country, and a low prestige third country, with three different brand name, price, and satisfaction guarantee levels. The results, based on a probabilistic sample of 179 male, French‐speaking individuals, indicate that the effect of price on perceptions of purchase value is generally not very important. Brand name is the most important informational cue for automobiles, product warranty for VCRs, and country of origin for T‐shirts. It seems that the informational value of country of origin varies across product classes that differ in involvement level and with the availability of other extrinsic cues to consumers. Managerial implications for multi‐cue marketing strategy are drawn from the results of the study.
Les PME peuvent‐elles manifester une certaine logique stratégique? L'utilisation d'une approche pour l'identifier
Authors: D'Amboise Gérald , Fortin Christiane , Gamier Bernard
Published: September 2010

Cet article propose une façon de classifier les tactiques ou stratégies de concurrence des PME et d'identifier la logique stratégique sous‐jacente aux activités quotidiennes de ces entreprises. La grille s'inspire du modèle de Porter; elle est toutefois élargie pour mieux correspondre aux activités concrètes des petites et moyennes entreprises. La grille est appliquée aux données recueillies auprès d'un échantillon de 60 PME manufacturières québécoises; elle permet de distinguer les firmes qui suivent l'une ou l'autre des logiques possibles. Les résultats aident à mieux comprendre les aspects théoriques et pratiques du débat sur les possibilités de donner une orientation stratégique aux entreprises de taille réduite.

This article classifies the tactics or strategies of small and medium‐sized businesses, using an extension of the Porter model. It allows consideration of more detailed competitive activities which can be found in the specific management of SMEs. It was used to analyze the data gathered from 60 firms engaged in manufacturing operations in the province of Québec. Everyday activities were assigned to their underlying generic strategy. The discussion of the results clarifies the issues at stake in the traditional debate over the possibility of strategically conducting lesser size enterprises.
Estimating the Carbon Footprint of Telecommunications Products: A Heuristic Approach
Authors: Joyce Toby , Okrasinski Thomas A. , Schaeffer William
Published: September 2010

Estimation of the carbon footprint for telecommunications and electronics products has become a key design activity. Improvement in carbon footprint must be demonstrated consistently on all new products. Current methods of providing a useful estimate are laborious and time-consuming. A simplified approach is described, which uses basic statistical methods for estimation and promises significant improvements over existing methods.
A method for Estimating the Degree of Uncertainty With Respect to Life Cycle Assessment During Design
Authors: Kota Srinivas , Chakrabarti Amaresh
Published: September 2010

Life cycle assessment (LCA) is used to estimate a product’s environmental impact. Using LCA during the earlier stages of design may produce erroneous results since information available on the product’s lifecycle is typically incomplete at these stages. The resulting uncertainty must be accounted for in the decision-making process. This paper proposes a method for estimating the environmental impact of a product’s life cycle and the associated degree of uncertainty of that impact using information generated during the design process. Total impact is estimated based on aggregation of individual product life cycle processes impacts. Uncertainty estimation is based on assessing the mismatch between the information required and the information available about the product life cycle in each uncertainty category, as well as their integration. The method is evaluated using pre-defined scenarios with varying uncertainty.
Optimal Plug-In Hybrid Electric Vehicle Design and Allocation for Minimum Life Cycle Cost, Petroleum Consumption, and Greenhouse Gas Emissions
Authors: Shiau Ching-Shin Norman , Kaushal Nikhil , Hendrickson Chris T. , Peterson Scott B. , Whitacre Jay F. , Michalek Jeremy J.
Published: September 2010

Plug-in hybrid electric vehicle (PHEV) technology has the potential to reduce operating cost, greenhouse gas (GHG) emissions, and petroleum consumption in the transportation sector. However, the net effects of PHEVs depend critically on vehicle design, battery technology, and charging frequency. To examine these implications, we develop an optimization model integrating vehicle physics simulation, battery degradation data, and U.S. driving data. The model identifies optimal vehicle designs and allocation of vehicles to drivers for minimum net life cycle cost, GHG emissions, and petroleum consumption under a range of scenarios. We compare conventional and hybrid electric vehicles (HEVs) to PHEVs with equivalent size and performance (similar to a Toyota Prius) under urban driving conditions. We find that while PHEVs with large battery packs minimize petroleum consumption, a mix of PHEVs with packs sized for ∼25–50 miles of electric travel under the average U.S. grid mix (or ∼35–60 miles under decarbonized grid scenarios) produces the greatest reduction in life cycle GHG emissions. Life cycle cost and GHG emissions are minimized using high battery swing and replacing batteries as needed, rather than designing underutilized capacity into the vehicle with corresponding production, weight, and cost implications. At 2008 average U.S. energy prices, Li-ion battery pack costs must fall below $590/kW h at a 5% discount rate or below $410/kW h at a 10% rate for PHEVs to be cost competitive with HEVs. Carbon allowance prices offer little leverage for improving cost competitiveness of PHEVs. PHEV life cycle costs must fall to within a few percent of HEVs in order to offer a cost-effective approach to GHG reduction.
A Schematic Method for Sustainable Material Selection of Toxic Chemicals in Design and Manufacturing
Authors: Yuan Chris Y. , Dornfeld David A.
Published: September 2010

Toxic chemicals used in product design and manufacturing are grave concerns due to their toxic impact on human health. Implementing sustainable material selection strategies on toxic chemicals can substantially improve the sustainability of products in both design and manufacturing processes. In this paper, a schematic method is presented for characterizing and benchmarking the human health impact of toxic chemicals, as a visual aid to facilitate decision-making in the material selection process for sustainable design and manufacturing. In this schematic method, the human health impact of a toxic chemical is characterized by two critical parameters: daily exposure risk R and environmental persistence T. The human health impact of a toxic chemical is represented by its position in the R−T two-dimensional plot, which enables the screening and benchmarking of toxic chemicals to be easily made through comparing their relative positions in the characterization plot. A case study is performed on six toxic chemicals commonly used as solvents for cleaning and degreasing in product development and manufacturing.
Design for Lifecycle Cost Using Time-Dependent Reliability
Authors: Singh Amandeep , Mourelatos Zissimos P. , Li Jing
Published: September 2010

Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. As time progresses, the product may fail due to time phenomena such as time-dependent operating conditions, component degradation, etc. The degradation of reliability with time may increase the lifecycle cost due to potential warranty costs, repairs, and loss of market share, affecting the sustainability of environmentally friendly products. In the design for lifecycle cost, we must account for product quality and time-dependent reliability. Quality is a measure of our confidence that the product conforms to specifications as it leaves the factory. Quality is time independent, and reliability is time dependent. This article presents a design methodology to determine the optimal design of time-dependent multiresponse systems by minimizing the cost during the life of the product. The conformance of multiple responses is treated in a series-system fashion. The lifecycle cost includes a production, an inspection, and an expected variable cost. All costs depend on quality and/or reliability. The key to our approach is the calculation of the so-called system cumulative probability of failure. For that, we use an equivalent time-invariant “composite” limit state and a niching genetic algorithm with lazy learning metamodeling. A two-mass vibratory system example and an automotive roller clutch example demonstrate the calculation of the cumulative probability of failure and the design for lifecycle cost.
Product Life-Cycle Modeling and Evaluation at the Conceptual Design Stage: A Digraph and Matrix Approach
Authors: Anand A. , Wani M. F.
Published: September 2010

An evaluation procedure for product life-cycle design at the conceptual stage is presented using a digraph and matrix approach. Life-cycle design attributes are identified and used to evaluate a life-cycle design index. The ideal value of this index is also obtained, which is useful in assessing the relative life-cycle design value of product design alternatives. A step-by-step procedure for the evaluation of the life-cycle design index is presented and illustrated by means of two examples.
An Actively Controlled Hydraulic Carbody Centering System for the Lateral Suspensions of High Speed Trains
Authors: Jacazio Giovanni , Magnani Alberto , Gastaldi Laura , Balossini Gualtiero
Published: September 2010

High speed trains normally use pneumatic actuation systems to recenter the carbody with respect to the bogie when the train negotiates a curve. Pneumatic systems are used because of their compliance, necessary to ensure dynamic isolation between carbody and bogie, but have the drawbacks of large dimensions and slow response, often accompanied by a few damped oscillations. An innovative solution was developed using hydraulic actuators with an adaptive control law providing the actuators with artificial compliance, hence making them suitable for this application. A carbody centering system is thus obtained presenting fast response, small volume and the necessary compliance. The optimal control law for this system was defined, the system dynamic characteristics were analyzed and a technological demonstrator was built to assess the system merits. The paper presents the theoretical grounds for the system control, its implementation and performance, and the most significant test results obtained with the technological demonstrator.
Enabling Air-Path Systems for Homogeneous Charge Compression Ignition (HCCI) Engine Transient Control
Authors: Yan Fengjun , Wang Junmin
Published: September 2010

This paper explores the possibility of using a cost-effective air-path system that includes a dual-loop (exhaust gas recirculation) EGR and a (variable geometry turbocharger) VGT to achieve independent control of the main in-cylinder charge conditions (i.e. in-cylinder oxygen, inert gas amounts, and gas temperature at the intake valve closing) for HCCI engine combustion transient operation. An engine simulation model consisting of the air-path system and a HCCI combustion model was developed and synthesized to evaluate the control authority of the air-path system on the in-cylinder charge conditions as well as their effects on combustion. A variety of simulations unveiled that such an air-path system can enable independent control of the main in-cylinder charge conditions and active compensation of the effects of the wall temperature variations on HCCI combustion.
Combined Component Swapping Modularity for a VCT Engine Controller
Authors: C¸akmakcı Melih , Ulsoy A. Galip
Published: September 2010

The use of bi-directional communication provides additional design freedom which can be used to maximize the swapping modularity of networked smart components. In this paper, application of a design method for combined swapping modularity of two or more system components is discussed. Development of measures for combined swapping modularity is important to be able to analyze more realistic engineering cases. The combined modularity problem is a more difficult problem compared to the individual component swapping modularity problem. First, two approaches (simultaneous and sequential) for combining component swapping modularity of two or more components are presented. Then these combined modularity approaches are used to design controllers which maximize the component-swapping modularity of the Variable Camshaft Timing (VCT) component (i.e. actuator and sensor) and the Exhaust Gas Oxygen (EGO) sensor for an internal combustion engine.
Observer-Based Control of Nonlinear Time-Delay Systems in Lower-Triangular Form
Authors: Ibrir Salim
Published: September 2010

Time-delay systems is a special class of dynamical systems that are frequently present in many fields of engineering. It has been shown in the literature that the existence of a stabilizing observer-based controller is related to delay-dependent conditions that are generally satisfied for a small time delay. Motivating works towards reducing the conservatism of the results are among the on-going research topics especially when partial-state measurements are imposed. This paper investigates the problem of observer-based stabilization of a class of time-delay nonlinear systems written in triangular form. First, we show that a delay nonlinear observer is globally convergent under the global Lipschitz condition of the system nonlinearity. Then, it is shown that a parameterized linear feedback that uses the observer states can stabilize the system whatever the size of the delay. Illustrative example is provided to approve the theoretical results.
Control of Electric Motor Systems Considering Input/Output Saturation
Authors: Kong Kyoungchul , Kniep Helge C. , Tomizuka Masayoshi
Published: September 2010

Input saturation is a well-known nonlinearity in mechanical control systems; it constrains the maximum acceleration, which results in a limitation of the system response time. Input saturation has been considered in controller design in various ways, e.g., anti-windup control. In addition to the input, the state variables of mechanical systems are often subject to saturation. For example, the maximum angular velocity of electric motor systems is limited by the maximum voltage provided for the motor. In the case of electronically commutated motors (i.e. brushless DC motors) the maximum speed is additionally constrained by limitations of the servo amplifier output. If gears are utilized, further constraints are introduced due to resonances in ball bearings and/or velocity dependent friction. Although such factors are significant in practice, they have not been fully considered in controller design. This paper investigates the input and output saturations and presents how they may be considered in the controller design; a Kalman filter, a PID controller, and a disturbance observer are designed in view of input/output saturations. A case study is provided to verify the proposed methods.
Experimental Investigation Into Improved Wrapper Control of Hot Strip Steel Rolling Mill Downcoilers
Authors: Davies D. Ll. , Watton J. , Xue Y. , Williams G. A.
Published: September 2010

With increasing international competition in steel production mainly from developing nations, it is important for steel plants to keep up to date with new technologies, and continuously improve on current practices and manufacturing techniques to remain competitive. This paper looks specifically at improvements to the hot rolling mill downcoilers, which is where the strip is coiled at the end of the rolling process. Hydraulic and pneumatic technology is combined to give accurate position control of guide wrappers that aid the initial coiling process. The paper presents an experimental test rig, using an actual wrapper guide, constructed to evaluate the specific design approach.
Sliding Mode Control of a Dual-Fuel System Internal Combustion Engine
Authors: Pace Stephen , Zhu Guoming G.
Published: September 2010

Air-to-fuel (A/F) ratio is the mass ratio of air-to-fuel mixture trapped inside a cylinder before combustion begins, and it affects engine emissions, fuel economy, and other performances. Using an A/F ratio and dual-fuel ratio control oriented engine model, a multi-input-multi-output (MIMO) sliding mode control scheme is used to simultaneously control the mass flow rate of both port fuel injection (PFI) and direct injection (DI) systems. The control target is to regulate the A/F ratio at a desired level (e.g., at stoichiometric) and fuel ratio (ratio of PFI fueling vs. total fueling) to a given desired level between zero and one. A MIMO sliding mode controller was designed with guaranteed stability to drive the system A/F and fuel ratios to the desired target under various air flow disturbances. The performance of the sliding mode controller was compared with a baseline multi-loop PID (Proportional-Integral-Derivative) controller through simulations and showed improvements over the baseline controller.
Charge-Balanced Optimal Inputs for Phase Models of Spiking Neurons
Authors: Nabi Ali , Moehlis Jeff
Published: September 2010

The optimal input current for a reduced neuron model and a specific target spiking time is obtained. The objective of optimization is to minimize the total input energy to the system subject to a zero net input integral over the time horizon. This “charge-balance constraint” ensures that no net external charge is injected into the neuron. The results are compared to optimal currents for which the charge-balance constraint is not imposed.
Improved Parameter Estimation by Noise Compensation in the Time-Scale Domain
Authors: McCusker James R. , Currier Todd , Danai Kourosh
Published: September 2010

It was shown recently that parameter estimation can be performed directly in the time-scale domain by isolating regions wherein the prediction error can be attributed to the error of individual dynamic model parameters [1]. Based on these single-parameter attributions of the prediction error, individual parameter errors can be estimated for iterative parameter estimation. A benefit of relying entirely on the time-scale domain for parameter estimation is the added capacity for noise suppression. This paper explores this benefit by introducing a noise compensation method that estimates the distortion by noise of the prediction error in the time-scale domain and incorporates it as a confidence factor when estimating individual parameter errors. This method is shown to further improve the estimated parameters beyond the time-filtering and denoising techniques developed for time-based estimation.
Modeling of Complex Hydronic Systems for Energy Efficient Operation
Authors: Chandan Vikas , Zak Gina , Alleyne Andrew
Published: September 2010

Energy requirements for heating and cooling of residential, commercial and industrial spaces constitute a major fraction of end use energy consumed. Centralized systems such as hydronic networks are becoming increasingly popular to meet those requirements. Energy efficient operation of such systems requires intelligent energy management strategies, which necessitates an understanding of the complex dynamical interactions among its components from a mathematical and physical perspective. In this work, concepts from linear graph theory are applied to model complex hydronic networks. Further, time-scale decomposition techniques have been employed to obtain a more succinct representation of the overall system dynamics. Lastly, the usefulness of the proposed model for energy efficient operation of the system through advanced control techniques has been discussed.
The Mix Estimation Algorithm for Battery State-of-Charge Estimator: Analysis of the Sensitivity to Model Errors
Authors: Codeca` Fabio , Savaresi Sergio M. , Manzoni Vincenzo
Published: September 2010

The problem considered in this paper is the analysis of a battery State-of-Charge estimation algorithm: in particular the mix estimation algorithm. This algorithm provides the estimation mixing two estimation approaches: namely the Coulomb-Counting and the Model-Based. The mix algorithm is qualitatively able to provide a more robust and accurate estimation respect to the estimation provided by the approaches the algorithm mixes together. The aim of this paper is to analyze the differences between the three algorithms and the advantages produced by the mixing procedure. In particular the paper presents the comparison of the mix algorithm behavior with the Coulomb-Counting and the Model-Based behaviors in case of model errors.
Validation of Dynamic Models by Image Distances in the Time-Scale Domain
Authors: Danai Kourosh , McCusker James R. , Currier Todd , Kazmer David O.
Published: September 2010

Model validation is the procedure whereby the fidelity of a model is evaluated. The traditional approaches to dynamic model validation either rely on the magnitude of the prediction error between the process observations and model outputs or consider the observations and model outputs as time series and use their similarity to assess the closeness of the model to the process. Here, we propose transforming these time series into the time-scale domain, to enhance their delineation, and using image distances between these transformed time series to assess the closeness of the model to the process. It is shown that the image distances provide a more consistent measure of model closeness than available from the magnitude of the prediction error.
Iterative Controller Tuning in the Time-Scale Domain
Authors: McCusker James R. , McKinley Michael G. , Danai Kourosh
Published: September 2010

A novel method of controller tuning is introduced to achieve a desired closed-loop response. It uses the same strategy as Iterative Feedback Tuning (IFT), but instead of relying on a scalar cost function of the performance error between the desired response and system response, it utilizes the expanded version of the performance error in the time-scale domain for estimating the suitable controller parameters. The proposed method relies on the enhanced delineation of output sensitivities in the time-scale domain to identify regions in the time-scale domain wherein the performance error can be attributed to individual controller parameters [1]. It then relies on the error association in each region to estimate the corresponding controller parameter. It is shown that given a realistic desired response for the closed-loop system, the proposed method can lead to satisfactory controller parameters. It is also shown that the results from this method can be integrated with those from IFT to represent the best of the two solutions from the time and time-scale domains.
The Multi-Variable Torque-Displacement Relation at the Ankle
Authors: Lee Hyunglae , Ho Patrick , Krebs Hermano Igo , Hogan Neville
Published: September 2010

In this paper, we report measurements of the multi-variable torque-displacement relation at the ankle. The passive behavior of the ankle in two degrees of freedom (inversion-eversion and dorsiflexion-plantarflexion) was quantified using the Anklebot. The measured torque-displacement relationship was represented as a vector field using thin-plate spline smoothing with generalized cross validation. Analysis of the experimental results showed that, when maximally relaxed, the ankle behaved like a mechanical spring. However, if muscles were active, the torque-displacement relation was not spring-like. Implications for the contribution of neural feedback to ankle impedance are discussed.
Nonlinear Observers for Constrained Systems
Authors: Kfoury Giscard A. , Chalhoub Nabil G.
Published: September 2010

Three procedures for designing robust observers to estimate the state variables of nonlinear constrained systems have been developed in this work. All observers are based on the sliding mode methodology and assume that the number of transducers matches that of the degrees of freedom of the system. The conceptual differences between the proposed observer designs are in the number and selection of the sliding surfaces along with the formulations pertaining to their nominal models. The observers have been applied to estimate the state variables of a crank-slider mechanism of a single cylinder engine. The simulation results demonstrate the capabilities of the observers in accurately estimating the state variables of the system, including the superfluous ones, in the presence of significant structured and unstructured uncertainties. In addition, the results show that the nominal constraint equations are satisfied by the estimated state variables.
Model-Based Nonlinear Control of a New Active Tilting-Pad Bearing
Authors: Wu An , de Queiroz Marcio
Published: September 2010

This paper introduces a new type of active fluid-film bearing and its feedback control. In particular, we propose to actively adjust the angular velocity of the pads of a tilting-pad bearing in response to changes in the operating conditions of the rotating machine. This is motivated by the observation that there is more control authority in the pad tilt motion than in its radial translation. To this end, we first develop a dynamic model for the bearing system, inclusive of the nonlinear hydrodynamic force for the infinitely-short bearing case. A model-based controller is then constructed, based on measurements of the journal position and velocity and pad tilt angles, to ensure that the journal is asymptotically regulated to the bearing center. Numerical simulations illustrate the performance of the active bearing under the proposed control in comparison with the bearing’s standard passive mode of operation.
Synthetic Wheel Prismatic Joint Biped With Torso
Authors: Flynn Louis L. , Jafari Rouhollah , Mukherjee Ranjan
Published: September 2010

The design of a new biped robot is proposed in this paper. Based on the concept of a self-propelled wheel, the design offers to provide impact-free motion during walking. The biped robot is composed of a torso and two legs. Each leg has arc-shaped feet that are constrained to move in a manner that essentially allows the robot to roll continuously during walking. The role of the torso is to generate forward and backward motion. The equations of motion of the robot are generated using Lagrange’s equations and constraints are imposed on the motion to generate a walking gait. In the experimental hardware, the constraints are imposed by designing and implementing closed-loop torque control of the actuators. The robot successfully walked down a hallway and data collected from the robot verified the efficacy of the controllers.
Digital Clay Force Observer Design and Shape Editing Concept
Authors: Ngoo Cheng Shu , Book Wayne J.
Published: September 2010

Digital Clay is a novel fluid-driven device for shape input/output that potentially has wide application in the areas of engineering, sciences, medicine, military, entertainment etc. Shape display is achieved with the current 5×5 prototype but this research seeks to expand its haptic capability with force feedback, but the absence of pressure/force sensors requires finger force estimation. In this paper, a velocity estimator and a mathematical model are derived for the design of a force observer. A brief overview of the current 5×5 prototype at the Georgia Institute of Technology and a new concept for shape editing are also given.
Optimal Control of a Magnetically Suspended Under Actuated Robot for Swing-Up Motion
Authors: Mazumdar Anirban , Asada H. Harry
Published: September 2010

This paper describes the analysis, design, and implementation of an under-actuated robot control system for swing up motion. The robot, called the “Mag-Foot” robot, uses permanent magnets to adhere to steel surfaces. This robot uses a novel tilting foot design for locomotion and can swing over small obstacles using an underactuated swinging motion. Since the robot can only adhere to the surface using limited (and relatively small) magnetic forces, it may fall down due to the reaction forces caused by the swing-up motion. To prevent failure, an optimal swing up trajectory is designed so that the maximum reaction force during the trajectory is minimized. The trajectories are parameterized using sigmoids and are determined by solving the dynamic equations as a 2 point boundary value problem. Finally, experiments are performed to evaluate the validity of this approach. The results of these experiments are promising and illustrate the validity of our approach.
A Unified Approach for Weighted Sensitivity Design of PID Controllers
Authors: Emami Tooran , Watkins John M.
Published: September 2010

In this paper a graphical technique is introduced for finding all continuous-time or discrete-time proportional integral derivative (PID) controllers that satisfy a weighted sensitivity constraint of an arbitrary order transfer function with time delay. These problems can be solved by finding all achievable PID controllers that simultaneously stabilize the closed-loop characteristic polynomial and satisfy constraints defined by a set of related complex polynomials. The key advantage of this procedure is that this method depends only on the frequency response of the system. The delta operator is used to describe the controllers in a discrete-time model, because it not only possesses numerical properties superior to the discrete-time shift operator, but also converges to the continuous-time controller as the sampling period approaches zero. A unified approach allows us to use the same procedure for discrete-time and continuous-time weighted sensitivity design of PID controllers.
A Multiattribute Utility Approach to Target Assignment
Authors: Chen Xi , Abbas Ali E. , Stipanovic´ Dusˇan M.
Published: September 2010

This paper introduces the multiattribute utility theory to the control Lyapunov function design framework. As an illustration we focus on the problem of multi-target assignment. With this formulation, we use a global multiattribute utility function as a multivariate objective function that should be minimized for the agents to achieve their objectives. The objectives represent deviations of each agent from specified targets. We provide closed form feedback control laws, based on the multiattribute utility function, for general nonlinear multi-agent system models affine in control. Finally, we present simulation results and conduct sensitivity analysis for two different models that are affine in control; basic kinematic model and nonlinear nonholonomic unicycle model.
Distributed Control of Two Dimensional Vehicular Formations: Stability Margin Improvement by Mistuning
Authors: Hao He , Barooah Prabir , Mehta Prashant G.
Published: September 2010

We consider distributed control of a large two-dimensional (planar) vehicular formation. An individual vehicle in the formation is assumed to be a fully actuated point mass. The control objective is to move the formation with a constant pre-specified velocity while maintaining constant inter-vehicle separation between any pair of nearby vehicles. The control law is distributed in the sense that the control action at each vehicle depends on the relative position measurements with nearby vehicles and its own velocity measurement. For this problem, a partial differential equation (PDE) model is derived to describe the spatio-temporal evolution of velocity perturbations for large number of vehicles, Nveh. The PDE model is used to deduce asymptotic formulae for the stability margin (absolute value of the real part of the least stable eigenvalue). We show that the stability margin of the closed loop decays to 0 as the number of vehicles increases, but the decay rate in 2D formation is much slower than in 1D platoons. In addition, the PDE is used to optimize the stability margin using a mistuning-based approach, in which the control gains of the vehicles are changed slightly from their nominal values. We show that the mistuning design reduces the loss of stability margin significantly even with arbitrarily small amount of mistuning. The results of the analysis with the PDE model are corroborated with numerical computation of eigenvalues with the state-space model of the vehicular formation.
Analysis and Control Design of a Hydro-Mechanical Hydraulic Hybrid Passenger Vehicle
Authors: Sim Teck Ping , Li Perry Y.
Published: September 2010

This paper gives the dynamic analysis of a hydro-mechanical transmission (HMT) drive train with regeneration and independent wheel torque control of a hydraulic hybrid passenger vehicle. From this analysis, we formulate the HMT control system, which is made up of high, mid and low-level control systems. The high-level consists of a state of charge management and the mid-level translates the storage requirement specified by the high-level into desired internal speed and gear ratio to be executed by the low-level. In this paper we focus on the low-level control analysis and design, where the actuation authority to regulate the internal speed variable comes from either the engine (mode 1) or the hydraulic system (mode 2). Experimental studies show good tracking performance of the proposed control systems and enable our vehicle system to be driven in the proposed HMT architecture.
Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve
Authors: Rannow Michael B. , Li Perry Y.
Published: September 2010

A method for significantly reducing the losses associated with an on/off controlled hydraulic system is proposed. There has been a growing interest in the use of on/off valves to control hydraulic systems as a means of improving system efficiency. While on/off valves are efficient when they are fully open or fully closed, a significant amount of energy can be lost in throttling as the valve transitions between the two states. A soft switching approach is proposed as a method of eliminating the majority of these transition losses. The operating principle of soft switching is that fluid can temporarily flow through a check valve or into a small chamber while valve orifices are partially closed. The fluid can then flow out of the chamber once the valve has fully transitioned. Thus, fluid flows through the valve only when it is in its most efficient fully open state. A model of the system is derived and simulated, with results indicating that the soft switching approach can reduce transition and compressibility losses by 79%, and total system losses by 66%. Design equations are also derived. The soft switching approach has the potential to improve the efficiency of on/off controlled systems and is particularly important as switching frequencies are increased. The soft switching approach will also facilitate the use of slower on/off valves for effective on/off control; in simulation, a valve with soft switching matched the efficiency an on/off valve that was 5 times faster.
Observer-Based Output Feedback Control of Nonlinear Systems Non-Affine in the Unmeasured States
Authors: Morel Yannick , Leonessa Alexander
Published: September 2010

The presented work addresses the output feedback control problem for a large class of nonlinear systems. The control strategy shares similarities to separation-based algorithms commonly found in the literature, in the sense that the control problem is solved using an observer-predictor, in conjunction with a state feedback control law. The approach however distinguishes itself in significant ways. In particular, the control algorithm is not designed to control the actual system’s output, as is usually the case in separation-based approaches, but it is rather designed to control the output of the observer-predictor. The latter is designed to ensure that, for any admissible control signal, its output converges to a neighborhood of the corresponding output of the real system. The observer-predictor is thus used to indirectly control the real system. Results of numerical simulations are provided to illustrate performance of the obtained control algorithm.
Wireless Piezoelectric Sensor for the Measurement of Tire Deformations and the Estimation of Slip Angle
Authors: Erdogan Gurkan , Alexander Lee , Rajamani Rajesh
Published: September 2010

This paper introduces a wireless piezoelectric tire sensor whose readings can be utilized for the estimation of various tire variables such as slip angle, slip ratio, tire forces and tire road friction coefficient. In this paper, the proposed sensor is demonstrated for the estimation of tire slip angle. Lateral deformation of the tire is decoupled from radial and longitudinal tire deformations using a special sensor design. The decoupled lateral deflection profile of the tire is employed to estimate the slip angle. A new tire test rig is constructed to experimentally evaluate the performance of the developed sensor. Results show that the tire sensor can accurately estimate slip angles up to values of 5.0 degrees.
Active Vibration Cancellation for Tire Road Friction Estimation
Authors: Erdogan Gurkan , Alexander Lee , Rajamani Rajesh
Published: September 2010

This paper focuses on the development and experimental evaluation of a novel adaptive feedforward vibration cancellation based friction estimation system. The friction estimation utilizes a small instrumented redundant wheel on the vehicle. Unlike other systems previously documented in literature, the developed system can provide a continuous measurement of the friction coefficient under all vehicle maneuvers, even when the longitudinal and lateral accelerations are both zero. A key challenge in the development of the estimation system is the need to remove the influence of vibrations and the influence of vehicle maneuvers from the measured signal of a force sensor. An adaptive feedforward algorithm based on the use of accelerometer signals as reference inputs is developed. The parameters of the feedforward model estimated by the adaptive algorithm themselves serve to determine the value of the friction coefficient. Detailed experimental results are presented on a skid pad wherein the road surface changes from dry asphalt to ice.
Feasibility Study on the Use of a Voice Coil Motor Direct Drive Flow Rate Control Valve
Authors: Wu Shuai , Burton Richard , Jiao Zongxia , Yu Juntao , Kang Rongjie
Published: September 2010

This paper considers the feasibility of a new type of voice coil motor direct drive flow control servo valve. The proposed servo valve controls the flow rate using only a direct measurement of the spool position. A neural network is used to estimate the flow rate based on the spool position, velocity and coil current. The estimated flow rate is fed back to a closed loop controller. The feasibility of the concept is established using simulation techniques only at this point. All results are validated by computer co-simulation using AMESim and Simulink. A simulated model of a VCM-DDV (Voice Coil Motor-Direct Drive Valve) and hydraulic test circuit are built in an AMESim environment. A virtual digital controller is developed in a Simulink environment in which the feedback signals are received from the AMESim model; the controller outputs are sent to the VCM-DDV model in AMESim (by interfacing between these two simulation packages). A LQR (Linear Quadratic Regulator) state feedback and nonlinear compensator controller for spool position tracking is considered as this is the first step for flow control. A flow rate control loop is subsequently included via a neural network flow rate estimator. Simulation results show that this method could control the flow rate to an acceptable degree of precision, but only at low frequencies. This kind of valve can find usage in open loop hydraulic velocity control in many industrial applications.
On the Geometric Characteristics of Cell Membrane Using Rotationally Oscillating Drill (Ros-Drill©)
Authors: Diaz Jhon , Karzar Jeddi Mehdi , Olgac Nejat , Fan Tai-Hsi , Ergenc Ali Fuat
Published: September 2010

ICSI (intracytoplasmic sperm injection) is a broadly utilized assisted reproductive technology. A number of new versions of the procedure have evolved lately, such as piezo-assisted ICSI technique. An important problem with this technique, however, is that it requires small amounts of mercury to stabilize the pipette tip. A completely different and mercury-free technology, called the “Ros-Drill©” (rotationally oscillating drill) was developed by the group of the authors. It uses microprocessor-controlled rotational oscillations of a spiked micropipette for piercing. One of the key issues is to determine when to start the oscillations. It is based on the cell deformation prior to the membrane piercing. In-situ measurements are needed for this protocol. The contribution of this paper is the utilization of computer vision for these measurements. The triggering logic is correlated to the cell membrane curvature variations along the vision-detected membrane line segment. Such a tool becomes very helpful for automating the Ros-Drill operation.
Experimental Evaluation of Two Bilateral Control Schemes Applied to a Tele-Operated Hydraulic Actuator
Authors: Zarei-nia Kurosh , Goharrizi Amin Yazdanpanah , Sepehri Nariman , Fung Wai-keung
Published: September 2010

Providing force feedback along with other sensory information can greatly increase task quality, productivity, and safety during teleoperation of hydraulic manipulators. However, as compared to the class of electrically-actuated robots, research on application of bilateral control schemes applied to the class of hydraulic manipulators is sparse. In this paper, we present experimental results of implementing two bilateral control scheme, previously developed for electrically-actuated manipulators, to a hydraulic actuator having additional nonlinear dynamics. The two schemes chosen are ‘force reflection’ and ‘position error’. The performance of each scheme is evaluated in terms of position tracking, force tracking, and fidelity of perceived stiffness by the human operator. The results reveal specific features of each scheme paving the road for future research in this direction in terms of designing appropriate bilateral control schemes for hydraulic manipulators.