bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparison of Bayesian and Maximum Likelihood Methods to Determine the Performance of a Point of Care Test for Helicobacter pylori in the Office Setting
Authors: Delaney Brendan C. , Holder Roger L. , Allan Teresa F. , Kenkre Joyce E. , Hobbs F. D. Richard
Published: July 2003

Objective. Evaluations of point of care tests (PCT) are often hampered by a lack of appropriate gold standards. This study aimed to compare the results of a Bayesian statistical analysis and a maximum likelihood method to evaluate the performance of a PCT for Helicobacter pylori in primary care. Methods. The Helisal Rapid Blood Test (Cortecs Diagnostics) was performed in 311 patients from 6 primary care centers, and a concurrent venous sample was taken for 2 enzyme linked immunosorbent assays (ELISA) performed at the laboratory, blind to the PCT result. The Bayesian analysis was conducted using Markov Chain Monte Carlo methods (WinBUGS). The performance characteristics of the PCT and the 2 ELISA tests were estimated together with 95% credible intervals (95% CIs). Results. The estimate of prevalence of H. pylori in this population was 64% (95% CI, 59% to 70%), the sensitivity and specificity of the PCT were 89% (84% to 94%) and 84% (77% to 91%), respectively (likelihood ratios positive 5.6, negative 0.13). The equivalent maximum likelihood results were prevalence, 65%; sensitivity, 90%; and specificity, 83%. Conclusions. The Helisal Rapid Blood Test performed as well as laboratory-based ELISA tests in this cohort of patients. The Bayesian analysis and the maximum likelihood method gave similar results, the Bayesian method also simultaneously estimating 95% CIs.
Learning Outcomes: Comparing Student Perceptions of Skill Level and Importance
Authors: Duke Charles R.
Published: July 2003

As an example of the assessment of learning outcomes, student perceptions were obtained for learning outcome importance as well as their own abilities to perform learning outcome skills. Development of outcomes involved multiple stakeholder groups and extensive reviews. Rankings were developed for highest importance and highest skill level as a way to evaluate outcomes needing emphasis. A simple priority index demonstrated one technique of allocating resources in program changes. In this example, highest priorities converged around issues of interpersonal, leadership, global economy, and interacting in the business environment. Extensive comparisons were made between class level as well as between marketing majors and other business disciplines. Although lists of outcomes, student perception ratings, and priorities will vary among institutions, this example indicated a beginning point for rating criteria.
Enhancing Student Motivation in Marketing Classes: Using Student Management Groups
Authors: Lilly Bryan , Tippins Michael J.
Published: July 2003

This article discusses student management groups (SMGs) and explains how these groups help stimulate class interaction and enhance student motivation to learn. After reviewing the concepts of motivation and immediacy, the article discusses how SMGs reduce perceived student-professor distance and encourage students to become more intrinsically motivated by participating in class governance issues. Presented next are the results of three studies. The first study examines qualitative feedback gathered from students and evaluates several benefits and drawbacks associated with using SMGs. A second study uses an experimental design to test the effects of SMGs on anticipated motivation across different class types. Finally, the third study reports feedback from professors to gauge their reactions to the SMG process. Research implications and suggestions for implementing SMGs are also discussed.
Pragmatic Discourse and Administrative Legitimacy
Authors: Box Richard C.
Published: July 2003

Legitimacy, the place of public administration in governance, has always been a concern in American society. Responses to this concern have included efforts to control bureaucracy by defining what it should do, to free it from control by elevating its status in relation to other branches of government, and to confine it to micro-level, market-like management techniques. The discourse theory of O. C. McSwite, based on pragmatism, suggests that governmental legitimacy in America may be revived by shifting from an emphasis on the public administrator’s role in directing agencies to thinking about how administrators may assist in creating community through collaboration with citizens. This article offers a critique and extension of McSwite’s work based in part on critical theory, arguing that to recover administrative legitimacy through collaborative discourse, it may be necessary to recognize and respond to the nature of the liberal-capitalist political environment.
Common Law, Equity, and American Public Administration
Authors: Green Richard T.
Published: July 2003

This article evaluates the claims of those who advocate the use of common law as a corrective to the statutory and rule-based excesses of the American administrative state. Their claims are assessed in light of common-law history and in terms of current administrative law. Although many claims are exaggerated or simply wrong, there are some aspects of common law that deserve attention in public administration. These are explained from the perspective of common-law evolution. Common law developed in a very pragmatic and experimental fashion and therefore displays some qualities public administrators will find useful, especially in the adjudicative realm of agency decisions, but more broadly as well. A model with five features of common-law practice is presented for public administrators to use in improving an agency’s decision making under law.
From Community Building to Governing Strangers
Authors: Sinclair Thomas A. P.
Published: July 2003

Community building, with its emphasis on developing capacities of organizations in low-income communities, is sparking wide interest among public administration practitioners and scholars. However, the community-building literature oversimplifies the complex relationships between individuals, community institutions, and government. Using a structuration approach theorized by Giddens, these interactions are explored using the arrival of new residents—or strangers—as the impetus for community redefinition. The article concludes that all types of communities, not just those typically targeted for community building may benefit from governmental interventions when undergoing transitions.
Learning to Govern Online
Authors: Mahler Julianne , Regan Priscilla M.
Published: July 2003

This research offers a limited empirical study of online service in federal government agencies. The authors are interested in the evolution of online governance and what factors influence the adoption and elaboration of online services. Information about online agency services was gathered primarily from online U.S. General Accounting Office reports and testimony offered between 1993 and 2000. The authors examine online activities that carry out three governmental functions: providing services, collecting information, and soliciting stakeholder comment. Four principal cases were selected: the Social Security Administration’s Online PEBES, the Department of Education’s National Student Loan Data System, the Securities and Exchange Commission, and the Nuclear Regulatory Commission. The analysis of these cases identifies a partial sequence of steps or stages in development of online services. It appears that this sequence is a result of both learning and the imposition of certain standards of performance based on best practices and legislative mandates.
The Reinvention Laboratories
Authors: Thompson James R.
Published: July 2003

The reinvention laboratories created as part of the National Performance Review represent a novel approach to strategic change in the federal government. In assigning an important role to middle management in the design and implementation of new work technologies, the lab program contrasts with more conventional approaches to change in which top management is dominant. This study examines the viability of the generative model that the lab program represents as a means of inducing agencies to employ postbureaucratic organizing principles. A conclusion is that although a variety of factors will affect the degree of success achieved, the model holds promise as a means of achieving strategic change in public organizations.
Comparing the Roles of Political Appointees and Career Executives in the U.S. Federal Executive Branch
Authors: Brewer Gene A. , Maranto Robert A.
Published: July 2003

This study uses Anthony Downs’s well-known typology of bureaucratic roles (climbers, conservers, advocates, zealots, and statesmen) as a theoretical template to examine the roles of political appointees and career executives serving in Washington, D.C. during the Reagan administration. Officials were asked to rank various personal goals in a 1987 survey. Political appointees were more likely to endorse climber (career advancement) and zealot (policy promotion) goals. Career executives were more likely to endorse advocate (support for the organization) responses. Notably, both political and career officials ranked zealot and statesman goals highly, suggesting that each group gains significant psychic income from supporting policies they believe in and from serving their country. Furthermore, each group was relatively unlikely to endorse conserver options, suggesting that those who reach the highest rungs of the civil service, whether political or career, are not motivated by job security or a limited workload.
Board Practices of Especially Effective and Less Effective Local Nonprofit Organizations
Authors: Herman Robert D. , Renz David O.
Published: July 2003

This study reviews evidence in support of the hypothesis that nonprofit organizations’effectiveness is related to the effectiveness of their boards of directors. It also asks whether various recommended board practices and processes affect board effectiveness. The study focuses on a subset of especially effective and less effective nonprofit organizations from a larger sample. The results show that the especially effective organizations (as judged by multiple stakeholders) have more effective boards (as judged by different multiple stakeholders) and that the more effective boards use significantly more of a set of recommended board practices. The results also show that nonprofit organizations using more of the prescribed board practices are also more likely to use other correct procedures. The results support the practical implication of urging the dissemination and adoption of the recommended practices.
“South of the Border”
Authors: Klingner Donald E.
Published: July 2003

This symposium assesses Mexico’s recent experiments with implementing new public management (NPM) reforms. The introduction describes Mexico’s characteristics, summarizes the history of NPM implementation there, and explores its underlying political and administrative rationale. Next, it introduces the three Mexican contributors and summarizes their respective presentations. Finally, it predicts the eventual outcome of NPM implementation in Mexico based on the critical issues that affect Mexican development, indicators for assessing progress, and the key role of public administration in the Mexican reform process.
Public Administrator Attitudes about Spirituality
Authors: Bruce Willa Marie
Published: July 2003

A random sample of members of the American Society for Public Administration (ASPA) were surveyed in regard to their views about spirituality in the public-sector workplace and whether spirituality should be discussed in their profession. Results of the survey are analyzed and reported. Based on these initial findings, it can be said that ASPA members who consider themselves to be spiritual have a substantially different worldview from those who are not spiritual, so they may behave differently in some ways at work and in the community than do their nonspiritual counterparts. Implications of these findings are discussed.
Municipal Government-Nonprofit Sector Collaboration in Bulgaria
Authors: Snavely Keith , Desai Uday
Published: July 2003

The worldwide phenomenon of devolution of power to local governments and growth of community nonprofit organizations increases opportunities for municipal government-nonprofit sector collaboration. Successful collaboration between the two institutions is seen as a promising trend because it stimulates development of a healthy civil society and delivery of a broader array of social services. This article presents an analysis of survey data that measured attitudes of Bulgarian municipal officials toward municipal-nonprofit collaboration. Municipal officials’ orientation toward working cooperatively with nonprofit organizations is critical to success. The survey data indicate that Bulgarian municipal officials are supportive of the general notion of municipal-nonprofit collaboration, but they retain serious reservations about the capacity of community nonprofit organizations to contribute meaningfully to service delivery in cooperation with local government. They perceive financial and human resource constraints within the nonprofit sector as well as within their own structures, thus making successful collaboration and its benefits problematic.
The Clinton Reforms and the Administrative Ascendancy of Congress
Authors: Thompson James R.
Published: July 2003

Early in the history of the National Performance Review (NPR), observers speculated that the prescriptions it contained, if implemented, would shift authority over the bureaucracy from the legislative branch to the executive branch. This review of the actual impact of NPR on relations between these key institutional actors finds that to the contrary, NPR has served to strengthen the congressional role in administrative matters in important ways. Key to this outcome has been the recent tendency, promoted by NPR, toward the disaggregation of administrative structures and systems in the federal government.
The Etiology of Administrative Evil
Authors: Moreno-Riaño Gerson
Published: July 2003

Administrative evil, as a research problem, is receiving attention in public administration research. Some of the literature suggests that administrative evil is caused by technical rationality. Although this may be so, technical rationality could also be considered symptomatic of a larger problem, one more directly causative of administrative evil. Exemplifying this claim is the organizational theory of Eric Voegelin. Voegelin, a political theorist, saw administrative evil resulting from the modern era’s refusal to consider existential questions, freedom, and human dignity as important dimensions of reality. Voegelin’s critique of modern organizations is presented along with his positive suggestions for organizational ethics. Last, some current ethical models are discussed that may encompass Voegelin’s ethical concerns.
Do Computers Cut Red Tape?
Authors: Peled Alon
Published: July 2003

Large public organizations that adopted computers in the early 1960s ever since have been accumulating “electronic mounds” consisting of layers upon layers of computer systems, data cemeteries, and software-inscribed, special case rules. These electronic mounds acquire a life of their own and are responsible for huge amounts of new electronic red tape that, in turn, inhibit flexibility, innovation, and reform. However, these electronic mounds are also the living carriers of organizational memory and needs, past and present. Organizations must learn how to coexist with their electronic mounds rather than constantly try to modernize them.
Values and Virtue
Authors: Arsneault Shelly
Published: July 2003

This article illustrates the concepts of morality policy and politics by examining the 1996 Title V federal grants for abstinence-only sex education. Drawing from the existing literature on morality policy and politics, it includes a theoretical framework for the study of morality policy and an analysis of abstinenceonly education as it was shaped at the federal, state, and local levels. Using the example of Title V in Kentucky, this case study well illustrates the expectations of conflict in adoption and controversy in implementation of morality policy. Furthermore, it provides an admonition for practitioners about compromise in even the most contentious morality policy battles.
Better, Faster, Stronger
Authors: Durst Samantha L. , Newell Charldean
Published: July 2003

The 1990s have been a period of intense reanalysis of what government does and of how it does it. As a result, public-sector organizations at the national, state, and local level are changing the way they do business to enhance performance, improve productivity, and champion customer service. This research analyzes the effects of reinventing government on selected public agencies. In general, survey respondents think reinvention activities have contributed to the development of more productive, more cost-conscious organizations offering enhanced services and improved performance. Regression results suggest that a number of different factors contribute to that thinking. These factors include the reasons that the governmental unit undertook reinvention activities and the internal and external actors involved in designing the reinvention.
Apples and Oranges?
Authors: de Soto William , Opheim Cynthia , Tajalli Hassan
Published: July 2003

This project builds on previous theoretical work that explores the differences between policy analysis and public administration/management approaches to public service education. Using survey data collected from public policy and public administration programs across the country, we test two aspects of public service education that may differ between public administration and public policy students: the psychological dispositions of students who enter each kind of program and the socializing effect of the respective curricula. With some exceptions, we find few differences in either area. Our research casts doubt on many of the preconceived notions of the differences in public policy versus public administration students and has important implications for public service education.
Assessing the Validity, Legitimacy, and Functionality of Performance Measurement Systems in Municipal Governments
Authors: Streib Gregory D. , Poister Theodore H.
Published: July 2003

There is now great interest in the use of performance measurement and there have been a number of studies that focused on municipal governments. The findings to date tend to be descriptive. This analysis seeks to add to this discussion by comparing real world conditions with the criteria outlined in a prescriptive model. The authors look at the validity, legitimacy, and functionality of municipal performance measures. The data on the use of performance measures come from a detailed survey that was mailed to all municipalities with populations larger than 25,000. The analysis identifies weaknesses in all of the areas that were examined, though there are a number of municipal governments that have developed very sophisticated performance measurement systems. The authors also offer some thoughts on what can be done to enhance municipal performance measures.
Community-Based Research and Changes in the Research Landscape
Authors: Chopyak Jill , Levesque Peter N.
Published: July 2003

This article argues that community-based research (CBR)—research that includes the participation of “lay” citizens in the research process—is changing the process of research and knowledge production. The article is an initial attempt to examine the outcomes of CBR and the impact such research is having on knowledge development and funding trends in North America. The article concludes with a set of policy recommendations and areas for further research.
Toward the Public Sphere—Reflections on the Development of Participatory Technology Assessment
Authors: Joss Simon
Published: July 2003

With the development and increasing use of diverse public involvement methods over the past decade, formal technology assessment has shifted from a largely closed, intrainstitutional tool of policy analysis and advice to a tool for the social assessment of scientific-technological issues at the interface between politics and public discourse. Through citizens’ conferences, scenario workshops, and consensus conferences, technology assessment has effectively been opened up to the public sphere: Citizens and interest group representatives are drawn into the process of assessing scientific and technological issues alongside experts, the process often takes place in public, and its outcomes are made widely available for information and debate. This article analyzes the public involvement agenda in technology assessment from the conceptual perspective of the “public sphere.” It discusses key features of public sphere–oriented technology assessment, including public access, actor involvement, and deliberation. And it considers the implications of the public sphere dimension for future developments in participatory technology assessment.
Learning From a University-Cosponsored Regional Consensus Conference
Authors: Hudspith Bob , Kim Mike
Published: July 2003

A consensus conference can be used to enable ordinary citizens to have informed input into policy making concerning controversial science and technology issues. To test whether this process could be used at a local level, facilitated by expertise from a university, McMaster University and the City of Hamilton, Ontario, cosponsored a regional consensus conference on waste management. This article describes this experience and evaluates it from three perspectives: how well the process satisfied the criteria of a good public participation process, how much impact the conference had, and how well the positive role envisioned for university involvement was satisfied. Lessons learned are outlined briefly.
Saying “Yes,”“No,” and “Load Me Up” to Guns in America
Authors: True James L. , Utter Glenn H.
Published: July 2003

Debate over gun control and gun rights has energized but not explained the seesaw nature of national gun policy making. Punctuated equilibrium theory (PET) aids in understanding that process, the gun policies it produces, and the roles of the ideologically opposed coalitions that are their sources. Gun ownership remains closely related to public preferences about gun policy, and the size of the gun-owning population has begun to diminish. In this analysis, the authors find that rifle and shotgun ownership responded little to national policy changes, but handgun ownership responded to both secular and policy influences. The results are that more Americans than ever before are saying “no” to gun ownership. Fewer are saying “yes,” but those who do own guns have been saying “load me up.” PET provides a framework for analyzing these changes and for anticipating some of their implications for public administrators.
A Need to Revamp Textbook Presentations of Price Elasticity
Authors: Dickinson John R.
Published: July 2003

Estimating price elasticity as commonly introduced in marketing textbooks is unrealistically simplistic. Actual estimation issubject to numerousconfounding factors. Generally, true price elasticity is not known and, thus, it is not possible to quantify deviation between estimated and true price elasticity. This study uses a simulation gaming platform where true price elasticity is known to compare estimated and true price elasticity. The results suggest that the simple formula and total revenue–price relationship estimation methods for price elasticity are subject to considerable error.
Argos: A Novel 3-DoF Parallel Wrist Mechanism
Authors: Vischer Peter , Clavel Reymond
Published: July 2003

This article presents a novel parallel spherical mechanism called Argos with three rotational degrees of freedom. Design aspects of the first prototype built of the Argos mechanism are discussed. The direct kinematic problem is solved, leading always to four nonsingular configurations of the end effector for a given set of joint angles. The inverse-kinematic problem yields two possible configurations for each of the three pantographs for a given orientation of the end effector. Potential applications of the Argos mechanism are robot wrists, orientable machine tool beds, joy sticks, surgical manipulators, and orientable units for optical components. Another pantograph based new structure named PantoScope having two rotational DoF is also briefly introduced.
On the Dynamics and Control of Flexible Multibody Systems with Closed Loops
Authors: Damaren Christopher J.
Published: July 2003

The motion control problem for cooperating flexible robot arms manipulating a large rigid payload is considered. An output that depends on the payload position and contributions from the joint motion of each arm is constructed whose rate yields the passivity property with respect to a special input. The input is a combination of the torques from each arm and contains a free load-sharing parameter. The passivity property is shown to depend on the payload mass properties, and in cases where the payload is large, a passivity-based controller combining feedforward and feedback as elements is devised, which yields tracking. An experimental facility consisting of two planar 3-DoF arms is used to implement the strategies. Good tracking is observed and compared with simulation predictions for closed-loop flexible multibody systems.
Gait Optimization through Search
Authors: Pal Prabir K. , Kar Dayal C.
Published: July 2003

We present a search-based method for the generation of a terrain-adaptive optimal gait of a six-legged walking machine. In this, several heuristic rules have been proposed to reduce the search effort. We identify the useful support states of the machine and form a table to indicate for each of these states the list of other states to which a transition can be made. This helps in converging to and maintaining a periodic gait through a limited search while retaining adequate options to deviate from such a gait as and when needed. The criterion for optimization is coded into a function that evaluates the promise of a node in the search graph. We have shown how this function may be designed to generate the common periodic gaits like the wave gait, the equal phase gait, and the follow-the-leader gait. The purpose is to demonstrate that the proposed method is sufficiently general and can cater to a wide range of optimizing requirements.
Coordinated Motion Planning for a Mobile Manipulator considering Stability and Manipulation
Authors: Huang Qiang , Tanie Kazuo , Sugano Shigeki
Published: July 2003

For a mobile manipulator to be used in areas such as offices and houses, it is desirable that the mobile platform be small sized. In the case of a small-sized platform, the mobile manipulator may tip over when moving at high speed or executing tasks in the presence of disturbances. Therefore, it is necessary to simultaneously consider both stabilization and manipulation while coordinating vehicle motion and manipulator motion. In this paper, we first present the concept of the valid stable region to evaluate stability in the presence of disturbances. Next, we propose a method for coordinating vehicle motion planning including manipulator configuration, and manipulator motion planning including platform stability. Then, the optimal problem of vehicle motion is formulated, taking into account vehicle dynamics, manipulator workspace, and system stability. Also, the manipulator motion is derived, considering stability compensation and manipulator configuration. Finally, the effectiveness of the proposed method is demonstrated by simulation examples.
Mobile Robot Localization from Large-Scale Appearance Mosaics
Authors: Kelly Alonzo
Published: July 2003

A new practical, high-performance mobile robot localization technique is described that is motivated by the fact that many man-made environments contain substantially flat, visually textured surfaces of persistent appearance. While the tracking of image regions is much studied in computer vision, appearance is still a largely unexploited localization resource in commercially relevant applications. We show how prior appearance models can be used to enable highly repeatable mobile robot guidance that, unlike commercial alternatives, is both infrastructure-free and free-ranging. Very large-scale mosaics are constructed and used to localize a mobile robot operating in the modeled environment. Straightforward techniques from vision-based localization and mosaicking are used to produce a field-relevant AGV guidance system based only on vision and odometry. The feasibility, design, implementation, and precommercial field qualification of such a guidance system are described.
Variable Constraint Mechanism and Its Application for Design of Mobile Robots
Authors: Hirose Shigeo
Published: July 2003

This paper describes the existence of one of the most useful mechanisms for robotic systems, coined the “variable constraint mechanism.” The variable constraint mechanism is a system that actively changes constraint conditions by itself, in response to the working purpose or the required motion sequence to acquire varied functionality. The paper discusses some of the generalized design principles for the mechanism and shows some example robotic systems, including an adjustable leg-length walking robot, a legged and wheeled hybrid vehicle, an autonomous multisection robot, and a planetary rover with collapsible frame and compressible wheels.
Probabilistic Algorithms and the Interactive Museum Tour-Guide Robot Minerva
Authors: Thrun S. , Beetz M. , Bennewitz M. , Burgard W. , Cremers A. B. , Dellaert F. , Fox D. , Hähnel D. , Rosenberg C. , Roy N. , Schulte J. , Schulz D.
Published: July 2003

This paper describes Minerva, an interactive tour-guide robot that was successfully deployed in a Smithsonian museum. Minerva’s software is pervasively probabilistic, relying on explicit representations of uncertainty in perception and control. During 2 weeks of operation, the robot interacted with thousands of people, both in the museum and through the Web, traversing more than 44 km at speeds of up to 163 cm/sec in the unmodified museum.
Context-Aware Shared Control of a Robot Mobility Aid for the Elderly Blind
Authors: Lacey Gerard , MacNamara Shane
Published: July 2003

This paper describes the use of a Bayesian network to provide context-aware shared control of a robot mobility aid for the frail blind. The robot mobility aid, PAM-AID, is a “smart walker” that aims to assist the frail and elderly blind to walk safely indoors. The Bayesian network combines user input with high-level information derived from the sensors to provide a context-aware estimate of the user’s current navigation goals. This context-aware action selection mechanism facilitates the use of a very simple, low bandwidth user interface, which is critical for the elderly user group. The PAM-AID systems have been evaluated through a series of field trails involving over 30 potential users.
Imaging Ladar for 3-D Surveying and CAD Modeling of Real-World Environments
Authors: Langer Dirk , Mettenleiter Markus , Härtl Franz , Fröhlich Christoph
Published: July 2003

To establish mobile robot operations and to realize survey and inspection tasks, robust and precise measurements of the geometry of the 3-D environment is a required basic sensor technology. For visual inspection, surface classification, and documentation purposes, however, additional information concerning reflectance of measured objects is necessary. High-speed acquisition of both geometric and visual information is achieved by the described active ladar, developed by Zoller and Fröhlich (Z+F). In contrast to other range-sensing devices, the Z+F system is designed for high-speed and high-performance operation in real indoor and outdoor environments, emitting a minimum of near-infrared laser energy. It integrates a single-point laser measurement system and a mechanical deflection system for 3-D environmental measurements. Experimental results are reported from surface inspections in tunnels, the generation of 3-D CAD models of a work cell in an automotive manufacturing plant, the modeling of free-form surfaces such as historic sculptures, and applications in mobile robot navigation.
Connectivity and Redundancy in Spatial Robots
Authors: Belfiore Nicola Pio , Di Benedetto Augusto
Published: July 2003

In this paper, the concepts of connectivity, degrees of control, and redundancy are revisited from a pure topological viewpoint and then applied to robotics. The redundancy matrix is defined to provide designers with a useful support in the first conceptual phase of the project of a new manipulator. An algorithm for building the connectivity and the redundancy matrices for a large class of manipulators is derived and implemented in an algebraic manipulation programming language. Based on some results borrowed from graph theory, the procedure can be used to study open-loop, closed-loop, and hybrid kinematic chains. In particular, it is shown how the biconnected components of the graph corresponding to the manipulator under analysis have to be detected for a correct computation of connectivity and redundancy. Furthermore, the study of the connectivity and of the degrees of control led to the development of a full mobility test that automatically detects the type of mobility of any given robot: total, partial, or fractionated. One of the presented sample cases offers the opportunity to discover some differences between the connectivity matrix obtained by means of the new algorithm and that presented, on the same kinematic chain, in a previous one.
A Galloping Horse Model
Authors: Herr Hugh M. , McMahon Thomas A.
Published: July 2003

A two-dimensional numerical model of a horse is presented that predicts the locomotory behaviors of galloping horses, including how stride frequency, stride length, and metabolic rate change from a slow canter to a fast gallop. In galloping, each limb strikes the ground sequentially, one after the other, with distinct time lags separating hind and forelimb footfalls. In the model, each stance limb is represented as an ideal linear spring, and both feed-forward and feedback control strategies determine when each limb should strike the ground. In a feed-forward strategy, the first hindlimb and the first forelimb to strike the ground are phase-locked such that the time separating their adjacent footfalls is held constant by the controller. In distinction, in a feedback strategy, the footfalls of the second hindlimb and the second forelimb begin when the first hindlimb and the first forelimb are perpendicular to the model’s trunk, respectively. While any limb is in contact with the ground, the controller also employs a feedback control to move each stance foot at a constant tangential velocity relative to the model’s trunk. With these control schemes, the galloping model remains balanced without sensory knowledge of its postural orientation relative to vertical. This work suggests that a robot will exhibit behavior that is mechanically similar to that of a galloping horse if it employs spring-like limbs and simple feed-forward and feedback control strategies for which postural stabilization is an emergent property of the system.
Virtual Model Control: An Intuitive Approach for Bipedal Locomotion
Authors: Pratt Jerry , Chew Chee-Meng , Torres Ann , Dilworth Peter , Pratt Gill
Published: July 2003

Virtual model control is a motion control framework that uses virtual components to create virtual forces generated when the virtual components interact with a robot system. An algorithm derived based on the virtual model control framework is applied to a physical planar bipedal robot. It uses a simple set of virtual components that allows the robot to walk successfully over level terrain. This paper also describes how the algorithm can be augmented for rough terrain walking based on geometric consideration. The resulting algorithm is very simple and does not require the biped to have an extensive sensory system. The robot does not know the slope gradients and transition locations in advance. The ground is detected using foot contact switches. Using the algorithm, we have successfully compelled a simulated seven-link planar biped to walk blindly up and down slopes and over rolling terrain.
Survey of Robotic Applications for Odor-Sensing Technology
Authors: Russell R. Andrew
Published: July 2003

This paper presents a review of the current status of chemical sensing as a sensory modality for mobile robots. Of the numerous techniques that are available for detecting chemicals, only a few have so far proved suitable for robotics applications. These are described and evaluated. To infer useful information from readings of chemical concentration, attention must be paid to the control and/or measurement of airflow close to the sensor. Experiments that incorporate aspects of airflow control and/or measurement are outlined. The information about chemical concentration is then used to control the motion of a robot. There follows a description of the reactive, often biologically inspired, control algorithms that have been used for this purpose. In conclusion, the present state of development of robotic chemical sensing is assessed.
Robot Hand-Eye Calibration Using Structure-from-Motion
Authors: Andreff Nicolas , Horaud Radu , Espiau Bernard
Published: July 2003

In this paper, we propose a new flexible method for hand-eye calibration. The vast majority of existing hand-eye calibration techniques require a calibration rig that is used in conjunction with camera pose estimation methods. Instead, we combine structure-from-motion with known robot motions, and we show that the solution can be obtained in linear form. The latter solves for both the hand-eye parameters and the unknown scale factor inherent with structure-from-motion methods. The algebraic analysis that is made possible with such a linear formulation allows investigation of not only the well-known case of general screw motions but also of such singular motions as pure translations, pure rotations, and planar motions. In essence, the robot-mounted camera looks to an unknown rigid layout, tracks points over an image sequence, and estimates the camera-to-robot relationship. Such a self-calibration process is relevant for unmanned vehicles, robots working in remote places, and so forth. We conduct a large number of experiments that validate the quality of the method by comparing it with existing ones.
Singularity Analysis of a Three-Leg Six-Degree-of-Freedom Parallel Platform Mechanism Based on Grassmann Line Geometry
Authors: Monsarrat Bruno , Gosselin Clément M.
Published: July 2003

This paper addresses the determination of the singularity loci of a six-degree-of-freedom spatial parallel platform mechanism of a new type that can be statically balanced. The mechanism consists of a base and a mobile platform that are connected by three legs using five-bar linkages. A general formulation of the Jacobian matrix is first derived that allows one to determine the Plücker vectors associated with the six input angles of the architecture. The linear dependencies between the corresponding lines are studied using Grassmann line geometry, and the singular configurations are presented using simple geometric rules. It is shown that most of the singular configurations of the three-leg six-degree-of-freedom parallel manipulator can be reduced to the generation of a general linear complex. Expressions describing all the corresponding singularities are then obtained in closed form. Thus, it is shown that for a given orientation of the mobile platform, the singularity locus corresponding to the general complex is a quadratic surface (i.e., either a hyperbolic, a parabolic, or an elliptic cylinder) oriented along the z-axis. Finally, three-dimensional representations that show the intersection between the singularity loci and the constant-orientation workspace of the mechanism are given.
Planning Motions Compliant to Complex Contact States
Authors: Ji Xuerong , Xiao Jing
Published: July 2003

Many robotic tasks require compliant motions, but planning such motions poses special challenges not present in collision-free motion planning. One challenge is how to achieve exactness, that is, how to make sure that a planned path is exactly compliant to a desired contact state, especially when the configuration manifold of such a contact state is hard to describe analytically due to high geometrical complexity and/or high dimensionality. The authors tackle the problem with a hybrid approach of direct exploitation of contact constraints and randomized planning. They particularly focus on planning motion that maintains certain contact state or contact formation (CF), called a CF-compliant motion, because a general compliant motion is a sequence of such CF-compliant motions with respect to different CFs. This paper describes a randomized planner for planning CF-compliant motion between two arbitrary polyhedral solids, extending the probabilistic roadmap paradigm for planning collision-free motion to the space of contact configurations. Key to this approach is a novel sampling strategy to generate random CF-compliant configurations. The authors also present and discuss examples of sampling and planning results.
Flexible Part Orienting Using Rotation Direction and Force Measurements
Authors: Rusaw Shawn , Gupta Kamal , Payandeh Shahram
Published: July 2003

This paper presents a novel sensor-based flexible part orienting system based on the commonly available force/torque sensor. The system orients planar parts arriving on a conveyor belt via a sequence of pushing operations with a force/torque sensor–equipped fence. A method of using the raw force data from the sensor to infer the rotation direction of the part is presented. Algorithms using (i) only rotation direction and (ii) rotation direction plus force information are presented. These algorithms find orienting plans with fewer steps than current sensorless orienting techniques, and for a number of specified part shape classes, current sensor-based techniques. Plans generated by these algorithms were tested and verified using a conveyor/robotic car test bed.
Edge-Projected Integration of Image and Model Cues for Robust Model-Based Object Tracking
Authors: Vincze M. , Ayromlou M. , Ponweiser W. , Zillich M.
Published: July 2003

A real-world limitation of visual servoing approaches is the sensitivity of visual tracking to varying ambient conditions and background clutter. The authors present a model-based vision framework to improve the robustness of edge-based feature tracking. Lines and ellipses are tracked using edge-projected integration of cues (EPIC). EPIC uses cues in regions delineated by edges that are defined by observed edgels and a priori knowledge from a wire-frame model of the object. The edgels are then used for a robust fit of the feature geometry, but at times this results in multiple feature candidates. A final validation step uses the model topology to select the most likely feature candidates. EPIC is suited for real-time operation. Experiments demonstrate operation at frame rate. Navigating a walking robot through an industrial environment shows the robustness to varying lighting conditions. Tracking objects over varying backgrounds indicates robustness to clutter.
Positioning of Symmetric and Nonsymmetric Parts Using Radial and Constant Fields: Computation of All Equilibrium Configurations
Authors: Lamiraux Florent , Kavraki Lydia E.
Published: July 2003

Programmable force fields have been used as an abstraction to represent a whole new class of devices that have been proposed for part manipulation. The general idea behind these devices is that a force field is implemented in a plane upon which the part is placed. The forces and torques exerted on the contact surface of the part translate and rotate the part. Manipulation plans for these devices can therefore be considered as strategies for applying a sequence of force fields to bring parts to some desired configuration. Instances of these novel devices are currently implemented using microelectromechanical systems technology, small airjets, vibration, and small motors. Manipulation in this case is sensorless and nonprehensile and promises to address the handling of very small or very fragile parts, such as electronics components, that cannot be handled with conventional pick-and-place robotics techniques. In this paper, the authors consider the problem of bringing a part to a stable equilibrium configuration using force fields. The authors study the combination of a unit radial field with a small constant field. A part placed on the radial field moves toward the origin of the radial field but cannot be oriented due to symmetry. Perturbing the radial field with a constant force field breaks the symmetry and gives rise to a finite number of equilibria. Under certain conditions, there is a unique stable equilibrium configuration. For the case in which these conditions are not fulfilled, the authors provide a comprehensive and unified analysis of the problem that leads to an algorithm to compute all stable equilibrium configurations. The paper contains a detailed discussion on how to implement the algorithm for any part. In the analysis, the authors make extensive use of potential fields. Using the theory of potential fields, the stable equilibrium configurations of a part are equivalent to the local minima of a scalar function. The work presented in this paper leads to the design of a new generation of efficient, open-loop part feeders that can bring a part to a desired orientation from any initial orientation without the need of sensing or a clock.
Optimal Probing Strategies
Authors: Canny John , Paulos Eric
Published: July 2003

Probing is a common operation employed to reduce the position uncertainty of objects. This paper demonstrates a technique for constructing provably near-optimal probing strategies for precisely localizing polygonal parts. This problem is shown to be dual to the well-studied grasping problem of computing optimal finger placements as defined by B. Mishra and others. A useful quality metric of any given probing strategy can easily be computed from simple geometric constructions in the displacement space of the polygon. The approach will always find a minimal set of probes that is guaranteed to be near optimal for constraining the position of the polygon. The size of the resulting set of probes is within O(1) of the optimal number of probes and can be computed in O(n log2 n) time, whereas the exact optimal solution is in NP-hard. The result of this work is a probing strategy useful in practice for refining part poses.
Optimal Gaits for Dynamic Robotic Locomotion
Authors: Cortés Jorge , Martínez Sonia , Ostrowski James P. , McIsaac Kenneth A.
Published: July 2003

This paper addresses the optimal control and selection of gaits in a class of dynamic locomotion systems that exhibit group symmetries. The authors study near-optimal gaits for an underwater eel-like robot, although the tools and analysis can be applied more broadly to a large family of nonlinear control systems with drift. The approximate solutions to the optimal control problem are found using a truncated basis of cyclic input functions. This generates feasible paths that approach the optimal one as the number of basis functions is increased. The authors describe an algorithm to obtain numerical solutions to this problem and present simulation results that demonstrate the types of solutions that can be achieved. Comparisons are made with experimental data using the REEL II robot platform.