bluuebunny/crossref_metadata_2025 huggingface dataset:
Politicization and Responsiveness in the Regional Offices of the NLRB
Authors: Schmidt Diane E.
Published: July 2003

Societal, professional, and organizational pressures create opportunities in bureaucratic decision making for political forces to dominate policy implementation. The author examines regional decision making in the National Labor Relations Board (NLRB). Because earlier studies examine such decision making in NLRB regional offices from 1964 to 1986, they include no critical examinations of the impact of changes in partisan control, societal attitudes, the balance of power between employers and unions, and economic stability from 1986 to 1997. The author argues that these developments create important new constraints on the level of regional staff responsiveness and accountability to political interests. Using a dynamic model, the author examines the influence of national pressures, regional environmental influences, and previous decisions by regional staffs to dismiss and by clienteles to withdraw complaints. The results show that clienteles pursue cases strategically in response to expectations of favoritism from national forces, political strength at the regional level, and previous decisions and the contemporary success of opposing interests.
Teaching Strategic Marketing Models with Web-Based Business Intelligence Tools: Innovative Guided Marketing Analysis
Authors: Heinrichs John H. , Lim Jeen-Su , Hudspeth Lonnie J.
Published: July 2003

The current business environment faced by many firms is increasingly characterized by nimble competitors competing in a dynamic, global marketplace. These firms are required to transition into a global economy wherein competitive advantage is based on intangible, knowledge-based resources. Such a competitive environment hasplaced a premium on knowl edge workers possessing technical and nontechnical competencies at obtaining, framing, integrating, using, and sharing knowledge. To succeed in this environment, the knowledge workers must possess three critical knowledge management competencies. First, they must be proficient in the use of leading edge business intelligence tools. Second, they must understand and apply proven marketing models and business concepts. Finally, they must be skilled in critical questioning techniques and demonstrate strategic thinking. In this study, students use leading edge decision support applications to mine a multidimensional data warehouse. Then, using generated chartsand tables, they apply proven marketing models to discover “gold nuggets” of insights.
Student Satisfaction Guarantees: An Empirical Examination of Attitudes, Antecedents, and Consequences
Authors: Gremler Dwayne D. , McCollough Michael A.
Published: July 2003

In guaranteeing the satisfaction of undergraduate students with the instructor’s performance, Gremler and McCollough in previous studies reported that undergraduate studentsgen erally approve of the concept of offering a student satisfaction guarantee for a course. Although they provided both qualitative and quantitative measures of students’attitudes concerning the guarantee, left unresolved is how students’ attitudes toward the guarantee might possibly affect their attitudes toward their overall classroom experience, including their attitude of the instructor’s efforts, their own efforts, and their satisfaction with classroom learning outcomes. This research presents and empirically evaluates a student satisfaction guarantee model. Lessons learned have implications not only for student satisfaction guarantees but for service guarantees in general.
MAC Versus PC: Determinism and Randomness as Complementary Approaches to Robotic Exploration of Continuous Unknown Domains
Authors: Wagner Israel A. , Lindenbaum Michael , Bruckstein Alfred M.
Published: July 2003

Three methods are described for exploring a continuous unknown planar region by a group of robots having limited sensors and no explicit communication. We formalize the problem, prove that its off-line version is NP-hard, and show a lower bound on the length of any solution. Then a deterministic mark and cover (MAC) algorithm is described for the on-line problem using short-lived navigational markers as a means of navigation and indirect communication. The convergence of the algorithm is proved, and its cover time is shown to be the asymptotically optimal O(A/a), where A is the total area and a is the area covered by the robot in a single step. The MAC algorithm is tested against an alternative randomized probabilistic covering (PC) method, which does not rely on sensors but is still able to cover an unknown region in an expected time that depends polynomially on the dimensions of the region. Both algorithms enable cooperation of several robots to achieve faster coverage. Finally, we show that the two methods can be combined to yield a third, hybrid algorithm with a better trade-off between performance and robustness.
A Fast New Algorithm for a Robot Neurocontroller Using Inverse QR Decomposition
Authors: Morris A. S. , Khemaissia S.
Published: July 2003

A new adaptive neural network controller for robots is presented. The controller is based on direct adaptive techniques. Unlike many neural network controllers in the literature, inverse dynamical model evaluation is not required. A numerically robust, computationally efficient processing scheme for neural network weight estimation is described, namely, the inverse QR decomposition (INVQR). The inverse QR decomposition and a weighted recursive least-squares (WRLS) method for neural network weight estimation is derived using Cholesky factorization of the data matrix. The algorithm that performs the efficient INVQR of the underlying space-time data matrix may be implemented in parallel on a triangular array. Furthermore, its systolic architecture is well suited for VLSI implementation. Another important benefit of the INVQR decomposition is that it solves directly for the time-recursive least-squares filter vector, while avoiding the sequential back-substitution step required by the QR decomposition approaches.
Dynamics Simulation and Controller Interfacing for Legged Robots
Authors: Reichler Jesse A. , Delcomyn Fred
Published: July 2003

Dynamics simulation can play a critical role in the engineering of robotic control code, and there exist a variety of strategies both for building physical models and for interacting with these models. This paper presents an approach to dynamics simulation and controller interfacing for legged robots, and contrasts it to existing approaches.

We describe dynamics algorithms and contact-resolution strategies for multibody articulated mobile robots based on the decoupled tree-structure approach, and present a novel scripting language that provides a unified framework for control-code interfacing, userinterface design, and data analysis. Special emphasis is placed on facilitating the rapid integration of control algorithms written in a standard object-oriented language (C++), the production of modular, distributed, reusable controllers, and the use of parameterized signal-transmission properties such as delay, sampling rate, and noise.
Using the Time Petri Net Formalism for Specification, Validation, and Code Generation in Robot-Control Applications
Authors: Montano Luis , García Francisco José , Villarroel José Luis
Published: July 2003

The main objective of this paper is to show the advantages of using the time Petri net formalism for specification, validation, and code generation in robot-control applications. To achieve this objective, we consider as application the development of a control system for a mobile robot with a rotating rangefinder laser sensor with two degrees of freedom to be used in navigation tasks with obstacle avoidance. It is shown how the use of the time Petri net formalism in the whole development cycle can fulfilll the reliability requirement of real-time systems, make the system development easy and quick, strongly reduce the time for the testing and tuning phases and, therefore, reduce the development cost significantly. It allows verification of functional and temporal requirements, error detection in the early stages of the development cycle, and automatic code generation, avoiding coding mistakes. Experimental tests show that the theoretical results obtained from the analysis of formal system models match the real-time behavior of the robotic system.
Multivariable Stability of Force-Reflecting Teleoperation: Structures of Finite and Infinite Zeros
Authors: Daniel R. W. , McAree P. R.
Published: July 2003

This paper presents a stability analysis of force-position teleoperation under general end-effector contact. The analysis is based on the finite and infinite zero structure of the multivariable root-locus resulting from modulation of the environment stiffness. The starting point is an analysis of the stability of robot force control, motivated by the observation that the human-operator in a force reflection loop acts as a “force servo,” generating position commands in response to reflected force. Asymptotic root loci properties are used to establish passivity conditions on force feedback to give root locus interpretations of the well-known results that (1) feedback via the inverse joint Jacobian can lead to (kinematic) instability and that (2) passivity is preserved by kinematically proper force feedback through the transpose of the joint angle Jacobian. It is demonstrated that a fully constrained force-position teleoperation loop has an identical infinite zero structure to that of a slave manipulator under kinematically proper force control and that the dominant vibration modes of a force-position loop are fully described by a multivariable analogue of the single-input single-output pseudo-system investigated in a study by Daniel and McAree. Extension of the analysis to cover partial end-effector constraint provides a design tool for teleoperation control and serves to aid selection of teleoperation slave-arms. The paper concludes by giving a passivity condition for multiple-input multiple-output force-position teleoperation for stable contact against all environments.
Optimal Gait Selection for Nonholonomic Locomotion Systems
Authors: Ostrowski James P. , Desai Jaydev P. , Kumar Vijay
Published: July 2003

This paper addresses the optimal control and selection of gaits in a class of nonholonomic locomotion systems that exhibit group symmetries. We study optimal gaits for the snakeboard, a representative example of this class of systems. We employ Lagrangian reduction techniques to simplify the optimal control problem and describe a general framework and an algorithm to obtain numerical solutions to this problem. This work employs optimal control techniques to study the optimality of gaits and issues involving gait transitions. The general framework provided in this paper can easily be applied to other examples of biological and robotic locomotion.
Extended Kalman Filtering Applied to a Two-Axis Robotic Arm with Flexible Links
Authors: Lertpiriyasuwat Vatchara , Berg Martin C. , Buffinton Keith W.
Published: July 2003

An industrial robot today uses measurements of its joint positions and models of its kinematics and dynamics to estimate and control its end-effector position. Substantially better end-effector position estimation and control performance would be obtainable if direct measurements of its end-effector position were also used. The subject of this paper is extended Kalman filtering for precise estimation of the position of the end-effector of a robot using, in addition to the usual measurements of the joint positions, direct measurements of the end-effector position. The estimation performances of extended Kalman filters are compared in applications to a planar two-axis robotic arm with very flexible links. The comparisons shed new light on the dependence of extended Kalman filter estimation performance on the quality of the model of the arm dynamics that the extended Kalman filter operates with.
Singularity Analysis and Representation of the General Gough-Stewart Platform
Authors: St-Onge Boris Mayer , Gosselin Clément M.
Published: July 2003

In this paper, the singularity loci of the Gough-Stewart platform are studied and a graphical representation of these loci in the manipulator’s workspace is obtained. The algorithm presented is based on analytical expressions of the determinant of the Jacobian matrix, using two different approaches, namely, linear decomposition and cofactor expansion. The first approach is used to assess the effect of the architecture parameters on the nature of the singularity loci, while the second approach leads to a significant reduction of the computational complexity of the determinant. It is shown that, for a given orientation of the platform, the singularity locus in the Cartesian space is represented by a polynomial of degree three. Moreover, this polynomial equation is applied to several simplified Gough-Stewart architectures and it is shown that the expression is reduced when the base of the mechanism is coplanar and for other special geometries. A comparison with the results obtained using Grassmann geometry is then presented, which illustrates the advantages of using one single compact equation for the singularity loci. The generalization of Fichter’s singular configuration is also developed, and several observations are then made. Finally, a brief discussion on the architecture singularities is presented and a graphical representation of the singularity loci in the Cartesian workspace of the manipulator is obtained. Two examples clearly illustrate the usefulness of the results for the analysis and design of parallel manipulators.
A Configuration Manifold Embedding Model for Dynamic Control of Redundant Robots
Authors: Gu Edward Y. L.
Published: July 2003

This paper presents a configuration manifold embedding model that provides a new approach to dynamic model reduction and adaptive control of redundant robotic systems. The proposed model is developed based on a geometrical and topological analysis of configuration manifolds (C-manifolds) hidden behind every robotic dynamic system that commonly obeys the Lagrange equation. With a detailed study of the C-manifold immersion and embedding into Euclidean space, we show that for a redundant robotic system, a subtask decision by choosing a certain null solution is technically equivalent to the C-manifold embedization. A direct adaptive control strategy is then developed based on the C-manifold embedding model for a specific application to model reduction and control of redundant robotic systems with both main tasks and subtasks represented in Cartesian space. It is also demonstrated that making only a kinematics model for a redundant robot can do the dynamic control job. Finally, a computer simulation study shows the effectiveness of this adaptive control algorithm.
Human Safety Mechanisms of Human-Friendly Robots: Passive Viscoelastic Trunk and Passively Movable Base
Authors: Lim Hun-Ok , Tanie Kazuo
Published: July 2003

We would like to give robots the ability to secure human safety in human-robot collisions capable of arising in our living and working environments. However, unfortunately, not much attention has been paid to the technologies of human robot symbiosis to date because almost all robots have been designed and constructed on the assumption that the robots are physically separated from humans. A robot with a new concept will be required to deal with human-robot contact. In this article, we propose a passively movable human-friendly robot that consists of an elastic material-covered manipulator, passive compliant trunk, and passively movable base. The compliant trunk is equipped with springs and dampers, and the passively movable base is constrained by friction developed between the contact surface of the base and the ground. During unexpected collisions, the trunk and base passively move in response to the produced collision force. We describe the validity of the movable base and compliant trunk for collision force suppression, and it is demonstrated in several collision situations.
Control of Planar Rigid Body Sliding with Impacts and Friction
Authors: Partridge Chad B. , Spong Mark W.
Published: July 2003

In this paper, we continue our investigations into robotic air hockey by studying the problem of controlling the trajectory of a puck subject to impacts. Impacts are modeled using the Routh two-dimensional impact model, which incorporates the effects of spin and friction. Using this model, we derive an explicit mapping between preimpact and postimpact velocities of the puck as a function of the velocities of the impacting objects and the coefficients of restitution and friction. We will see that this mapping depends fundamentally on whether or not relative sliding between the objects occurs throughout the duration of the impact event, or terminates during the impact. We then present results on planning of puck trajectories and control of the puck through impacts with a mallet or striker, which is essentially the problem of inverting the mapping between preimpact and postimpact velocities. Our results confirm the intuitive notion that a large coefficient of friction between the mallet and puck, and between the puck and table walls, enhances the ability to control puck motion through impacts.
Stabilizing Impacts in Force-Reflecting Teleoperation Using Distance-to-Impact Estimates
Authors: McAree P. R. , Daniel R. W.
Published: July 2003

The level of force that can be stably reflected to the human operator in a force-reflecting teleoperator is constrained by the dynamics of impact between the slave arm and its environment. This paper models the underlying dynamics of impact and describes how the impact effects can be minimized using estimates of the distance between the slave and objects in its workspace. Our approach is based on stochastic variational principles and seeks to limit the momentum of the slave arm at impact. Preliminary experimental results show that the approach allows extension of the range of frequencies that can be stably reflected to the human operator.
Modeling and Dynamic Performance Evaluation of Target Capture in Robotic Systems
Authors: Kövecses József , Cleghorn William L. , Fenton Robert G.
Published: July 2003

In this paper, a dynamic system consisting of a robot manipulator and a target is analyzed. The target is considered in a general way as a dynamic subsystem having finite mass and moments of inertia (e.g., a rigid body or a second robot). The situation investigated is when the robot establishes interaction with the target in such a way that it intercepts and captures a reference element of the target. The analysis of target capture is divided into three phases in terms of time: the precapture, “free” motion (finite motion); the transition from free to constrained motion in the vicinity of interception and capture (impulsive motion); and the postcapture, constrained motion (finite motion). The greatest attention is paid to the analysis of the phase of transition, the impulsive motion, and dynamics of the system. Based on the use of impulsive constraints and the Jourdainian formulation of analytical dynamics, a novel approach is proposed for the dynamic modeling of target capture by a robot manipulator. The proposed approach is suitable to handle both finite and impulsive motions in a common analytical framework. Based on the dynamic model developed and using a geometric representation of the system’s dynamics, a detailed analysis and a performance evaluation framework are presented for the phase of transition. Both rigid and structurally flexible models of robots are considered. For the performance evaluation analyses, two main concepts are proposed and corresponding performance measures are derived. These tools may be used in the analysis, design, and control of time-varying robotic systems. The dynamic system of a three-link robot arm capturing a rigid body is used to illustrate the material presented.
Dynamics of a Mobile Robot with Three Ball-Wheels
Authors: Ostrovskaya S. , Angeles J. , Spiteri R.
Published: July 2003

A mathematical model is developed for a mobile robot with three ball-wheels. The resulting model turns out to be a Chaplygin system, which allows the dynamics equations and the kinematic constraints to be integrated separately. The system is driven by six actuators: one actuator connected to one roller of each wheel, and three more actuators controlling the orientation of the ball-carriers with respect to the platform. Analysis of the mathematical model of this system using the holonomy matrix yields conditions under which the system can be rendered holonomic. Holonomy can be achieved by keeping the ball-carriers in pure translational motion. Therefore, the control of the system can be simplified by imposing constraints on the ball-carriers that prevent them from changing their orientation with respect to an inertial frame.
Nonlinear PID Control with Partial State Knowledge: Damping without Derivatives
Authors: Armstrong Brian , Wade Bruce A.
Published: July 2003

Nonlinear PID (NPID) control is implemented by allowing the controller gains to vary as a function of system state. NPID control has been previously described and implemented, and recently a constructive Lyapunov stability proof has been given. The controllers arising with the constructive Lyapunov method will in general depend on knowledge of the full state vector. In the present work, NPID controllers that operate without knowledge of some state variables are demonstrated. A general but conservative design method is presented with an experimental demonstration. For a special case, complete necessary and sufficient conditions are established; for this case, simulation of a robotic force control application demonstrates well-damped control with no requirement for a force-rate signal. The extension to cases of partial state knowledge is important for NPID control, which is most practical when some state variables—particularly rate variables—are poorly known, confounding full-state feedback or other high-damping linear control designs. Extension of NPID control to MIMO systems and computed torque control is also shown.
On Ballistic Walking Locomotion of a Quadruped
Authors: Formal’sky A. , Chevallereau C. , Perrin B.
Published: July 2003

This paper investigates ballistic motions in walking quadrupeds on a horizontal plane. The study is carried out on a quadruped consisting of a body and four identical two-link legs. Each leg has a knee joint and is connected to the body by a haunch joint. Three types of quadruped gaits, bound, amble, and trot, are studied. None of these gaits complies with a flight phase, but they all involve simultaneous and identical motion of two legs. Muscle activities are commonly believed to alternate with periods of relaxation. Our study, therefore, assumes that the swing phase is ballistic, i.e., no active control torque is exerted. Ballistic motion is achieved through appropriate initial velocities. These velocities result from impulsive active control torques and ground reactions exerted at the boundary instants of the single support phase. Natural ballistic motions are shown to exist for the three gaits and for each valid walking velocity class. Torque cost analysis shows that amble and trot gaits are more efficient than bound.
A Survey of Global Configuration-Space Mapping Techniques for a Single Robot in a Static Environment
Authors: Wise Kevin D. , Bowyer Adrian
Published: July 2003

The mapping from workspace to configuration space (C-space) plays a major role in the field of kinematics, with applications including robotics path planning, packing and nesting, automated assembly, and mechanism analysis. Over the past 20 years, research into the problem has resulted in many techniques that can be combined to suit a specific application. This survey aims to provide the developer of a C-space-based system with an overview of those techniques that map the global C-space of a single robot in a static environment. We discuss issues concerning how the robot and its environment are modeled (including how approximations can be used to make C-space mapping easier) and describe a range of schemes used to represent a C-space map. We then discuss the key techniques used to generate a C-space map for mobile robots and manipulators. The survey of literature is summarized by tables that list some 50 individual mapmaking papers, classifying each according to criteria identified in earlier sections. Finally, we draw conclusions from the findings of the survey. Note that, although reference is made throughout to robots, the controlled objects may equivalently be components or assemblies. In particular, results for mobile robots are fundamental to all C-space mapmaking problems.
Eigenfrequencies Invariance Property in One-Link Robotic Arm
Authors: Rouff Marc , Cotsaftis Michel
Published: July 2003

In the study of eignefrequencies of robotic arms versus load, straightforward invariance property is singled out under a preload condition. We show that compliance does not affect this effect. This property opens the way to new robust and finite dimensional controllers.
A Set of Geometric Invariants for Kinematic Analysis of 6R Manipulators
Authors: Hongguang Fu , Lu Yang , Jingzhong Zhang
Published: July 2003

This paper proposes four geometric invariants to be used to eliminate joint variables in closure equations for a 6R manipulator instead of the Gaussian elimination used in other studies. The geometric invariants are determined by the structure of any three consecutive joints in space. They have specific geometric meanings such as angle, length, area, volume. For a general 6R manipulator, its four basic closure equations containing only three angular variables can be directly constructed in a few minutes from the geometric invariants using Maple on a general personal computer. These resulting equations have no extraneous roots and are algebraically independent. Because the basic closure equations are obtained from the geometric invariants, they have the most simple forms and provide a very good chance to solve the input-output equation for the inverse kinematics problem. As a result, we use the set of basic closure equations to derive the symbolic 16th degree input-output equation and compute the input-output equation for a special case with 16 different real solutions. All position and orientation coordinates of the end-effector may be symbolic parameters. The definition of the geometric invariants is independent of joint types and can be applied to manipulators with any serial geometry.
Mechanics, Planning, and Control for Tapping
Authors: Huang Wesley H. , Mason Matthew T.
Published: July 2003

We present analysis and experimental demonstration of manipulation by tapping. Our problem domain is positioning planar parts on a support surface by a sequence of taps; each tap imparts some initial velocities to the object, which then slides until it comes to rest due to friction. We formulate the mechanics of tapping for circular axisymmetric objects, show how to plan a single tap and a sequence of taps to reach a goal configuration, and present feedback control methods to robustly accomplish positioning tasks. With these methods, we have experimentally demonstrated positioning tasks using tapping, including high-precision positioning tasks in which the object is positioned more precisely than the tapping actuator. We show stability and sensitivity analysis in support of these results.
Feature Extraction from a Broadband Sonar Sensor for Mapping Structured Environments Efficiently
Authors: Kao Gordon , Probert Penny
Published: July 2003

In this paper, we describe the use of a broadband, frequency modulated sonar sensor (a CTFM sonar) for generating maps of structured environments for robots and autonomous systems. The major advantage of using these sensors is that the information generated is reliable enough to extract the geometry and type of certain features with very few measurements; hence, maps can be generated rapidly. Although the technology of low-cost CTFM sonar has been available for some time, it has only very recently been considered seriously as a candidate sensor for navigation and mapping in spite of its superior performance. We describe the operation of the sensor and the use of both the range-orientation and amplitude-orientation profiles to extract information online and point targets in both smooth and rough environments. We demonstrate the method through generating a map for a room typical of a modern building (in fact, in a domestic house), using resolution of scanning increment from 1.8 deg down to 10.8 deg. We examine the robustness of the method as the number of measurements is reduced through introducing two quality metrics for each map.
An Asynchronous, Robust, and Distributed Multisensor Fusion System for Mobile Robots
Authors: López-Orozco J. A. , de la Cruz J. M. , Besada E. , Ruipérez P.
Published: July 2003

In this paper, a multisensor fusion system that is used for calculating the position and orientation of an autonomous mobile robot is presented. The developed fusion system is distributed, robust, and asynchronous. It is distributed to permit the parallel function of all the sensors. It is robust because, being distributed, the system has been designed to keep working properly in spite of the failure, removal, or change of any sensor. It is asynchronous to take advantage of the different features and rates of each sensor. The implementation of the system is based on the distributed Kalman filter developed by Durrant-Whyte and Rao. In that distributed filter, all the sensors work in parallel to obtain their own estimate based on their own observations and on the observations coming from other sensors. Changes have been made to simplify and speed up the computation of the external validation equations and to allow the use of any sensor model. The equations have also been adapted to deal with asynchronously operating sensors and with the existence of communication delays. The fusion system is used to estimate the position and orientation of a mobile robot. The performance of the fusion system is shown both under simulation and in a real test with a mobile robot.
A Platform for Robotics Research Based on the Remote-Brained Robot Approach
Authors: Inaba Masayuki , Kagami Satoshi , Kanehiro Fumio , Hoshino Yukiko , Inoue Hirochika
Published: July 2003

Robots of the future will act in the real world. To realize robots with the common sense to do this will, it is generally believed, require massively parallel processing. This is a problem for those of us who want to do experiments with robots in the real world today—it is hard to build active, limber, situated robots when they have to carry along heavy brains. Our answer is “remote-brained robots.” A remote-brained robot is designed to have the brain and body separate, both conceptually and physically. It allows us to tie artificial intelligence (AI) with massive parallelism directly to the real world, enabling the verification of high-level AI techniques, which could previously only be used in simulation. Once the brain is placed remotely from the body, it encourages us to investigate many important research topics of embodied agents working in the real world. This paper describes such platform for future robotics and principal experiments done on the platform.
Robotic System Sensitivity to Neural Network Learning Rate: Theory, Simulation, and Experiments
Authors: Clark Christopher M. , Mills James K.
Published: July 2003

Selection of neural network learning rates to obtain satisfactory performance from neural network controllers is a challenging problem. To assist in the selection of learning rates, this paper investigates robotic system sensitivity to neural network (NN) learning rate. The work reported here consists of experimental and simulation results. A neural network controller module, developed for the purpose of experimental evaluation of neural network controller performance of a CRS Robotics Corporation A460 robot, allows testing of NN controllers using real-time iterative learning. The A460 is equipped with a joint position proportional, integral, and derivative (PID) controller. The neural network module supplies a signal to compensate for remaining errors in the PID-controlled system. A robot simulation, which models this PID-controlled A460 robot and NN controller, was also developed to allow the calculation of sensitivity to the NN learning rate. This paper describes the implementation of three NN architectures: the error back-propagation (EBP) NN, mixture of experts (ME) NN, and manipulator operations using value encoding (MOVE) NN. The sensitivity of joint trajectory error of three NN controllers to learning rate was investigated using both simulation and experimentation. Similar results were obtained from the robot experiments and the dynamic simulation. These results of state sensitivity to NN learning rate confirm that the MOVE NN is least sensitive to learning rate, implying that selection of suitable learning rates for this NN architecture for the system considered is accomplished more readily than other NN architectures.
Fine-Scale Three-Dimensional Mapping of a Deep-Sea Hydrothermal Vent Site Using the Jason ROV System
Authors: Yoerger Dana R. , Kelley Deborah S. , Delaney John R.
Published: July 2003

Using precise navigation, a computer-controlled remotely operated vehicle, and a variety of optical and acoustic imaging sensors, we created the most precise three-dimensional renderings ever made of an active hydrothermal vent field at a depth of 2400 meters on the deep sea floor. Data products included electronic and film photographs as well as three-dimensional sonar scans. We used these to produce detailed photomosaics and gridded surface renderings. Precise navigation and control of the vehicle during all transects permitted us to register all observations in a common world frame, ensured complete and uniform coverage, and allowed biases to be identified and removed. The assembled photomosaics and sonar renderings provide valuable insights into the unique environment of submarine hydrothermal vents.
Technology and Field Demonstration of Robotic Search for Antarctic Meteorites
Authors: Apostolopoulos Dimitrios S. , Wagner Michael D. , Shamah Benjamin N. , Pedersen Liam , Shillcutt Kimberly , Whittaker William L.
Published: July 2003

Meteorites are the only significant source of material from other planets and asteroids, and therefore are of immense scientific value. Antarctica’s frozen and pristine environment has proven to be the best place on earth to harvest meteorite specimens. The lack of melting and surface erosion keep meteorite falls visible on the ice surface in pristine condition for thousands of years. In this article, we describe the robotic technologies and field demonstration that enabled the first discovery of Antarctic meteorites by a robot. Using a novel autonomous control architecture, specialized science sensing, combined manipulation and visual servoing, and Bayesian classification, the Nomad robot found and classified five indigenous meteorites during an expedition to the remote site of Elephant Moraine in January 2000. This article first overviews Nomad’s mechatronic systems and details the control architecture that governs the robot’s autonomy and classifier that enables the autonomous interpretation of scientific data. It then focuses on the technical results achieved during field demonstrations at Elephant Moraine. Finally, the article discusses the benefits and limitations of robotic autonomy in science missions. Science autonomy is shown as a capable and expandable architecture for exploration and in situ classification. Inefficiencies in the existing implementation are explained with a focus on important lessons that outline future work.
PIRAT—A System for Quantitative Sewer Pipe Assessment
Authors: Kirkham Robin , Kearney Patrick D. , Rogers Kevin J. , Mashford John
Published: July 2003

Sewers are aging, expensive assets that attract public attention only when they fail. Sewer operators are under increasing pressure to minimise their maintenance costs, while preventing sewer failures. Inspection can give early warning of failures and allow economical repair under noncrisis conditions. Current inspection techniques are subjective and detect only gross defects reliably. They cannot provide the data needed to confidently plan long-term maintenance. This paper describes PIRAT, a quantitative technique for sewer inspection.PIRAT measures the internal geometry of the sewer and then analyses these data to detect, classify, and rate defects automatically using artificial intelligence techniques. We describe the measuring system and present and discuss geometry results for different types of sewers. The defect analysis techniques are outlined and a sample defect report presented. PIRAT’s defect reports are compared with reports from the conventional technique and the discrepancies discussed. We relate PIRAT to other work in sewer robotics.
Development and Control of a Holonomic Mobile Robot for Mobile Manipulation Tasks
Authors: Holmberg Robert , Khatib Oussama
Published: July 2003

Mobile manipulator systems hold promise in many industrial and service applications including assembly, inspection, and work in hazardous environments. The integration of a manipulator and a mobile robot base places special demands on the vehicle’s drive system. For smooth, accurate motion and coordination with an on-board manipulator, a holonomic vibration-free wheel system that can be dynamically controlled is needed. In this paper, we present the design and development of a powered caster vehicle (PCV), which is shown to possess the desired mechanical properties. To dynamically control the PCV, a new approach for modeling and controlling the dynamics of this parallel redundant system is proposed. The experimental results presented in the paper illustrate the performance of this platform and demonstrate the significance of dynamic control and its effectiveness in mobile manipulation tasks.
A Low-Cost, Redundant Inertial Measurement Unit for Unmanned Air Vehicles
Authors: Sukkarieh Salah , Gibbens Peter , Grocholsky Ben , Willis Keith , Durrant-Whyte Hugh F.
Published: July 2003

This paper discusses the development of a low-cost, redundant, strapdown inertial measurement unit (IMU). The unit comprises four ceramic vibrating structure gyroscopes and four QLC 400 accelerometers configured on a truncated tetrahedron design. This design allows for the optimal configuration of the eight sensors, which in turn provides for a theoretical 33% increase in information. The redundant sensor configuration also allows for fault detection, which is required for many autonomous applications. This initiative is a precursor for future developments with more sensors to provide fault isolation. The paper will also present a navigation system implementing the redundant IMU with the global positioning system. Results are provided of this navigation system being implemented in an unmanned air vehicle.
Orienting Toleranced Polygonal Parts
Authors: Akella Srinivas , Mason Matthew T.
Published: July 2003

Parts manufactured to tolerances have variations in shape. Most previous work in robotic manipulation assumes that parts do not have shape variations. Orienting devices such as bowl feeders often fail due to variations in part shape. We study the effects of uncertainty in part shape on orienting to develop systems that can orient toleranced polygonal parts. We present a tolerance model in which the part center of mass and vertices lie in circular uncertainty zones around their nominal positions. The variations in part shape are characterized by the tolerance model and the part’s nominal shape. We describe the nondeterminism that arises due to part shape uncertainty for a conveyor-based orienting system and show that sensor-based and sensorless orienting plans can exist for toleranced polygonal parts. We present implemented planners that generate orienting plans for the entire variational class of part shapes given a nominal part shape and tolerance bounds. These plans use both deterministic and nondeterministic actions to orient the parts, and we describe experiments to demonstrate them.
Collision-Free Trajectory Planning for a 3-DoF Robot with a Passive Joint
Authors: Lynch Kevin M. , Shiroma Naoji , Arai Hirohiko , Tanie Kazuo
Published: July 2003

This paper studies motion planning from one zero-velocity state to another for a three-joint robot in a horizontal plane with a passive revolute third joint. Such a robot is small-time locally controllable on an open subset of its zero-velocity section, allowing it to follow any path in this subset arbitrarily closely. However, some paths are “preferred” by the dynamics of the manipulator in that they can be followed at higher speeds. In this paper, the authors describe a computationally efficient trajectory planner that finds fast, collision-free trajectories among obstacles. The planner decouples the problem of planning feasible trajectories in the robot’s six-dimensional state space into the computationally simpler problems of planning paths in the three-dimensional configuration space and time scaling the paths according to the manipulator dynamics. This decoupling is made possible by the existence of velocity directions, fixed in the passive link frame, which can be executed at arbitrary speeds. Results of the planner have been implemented on an experimental underactuated manipulator. To the authors’ knowledge, it is the first implementation of a collision-free motion-planning algorithm for a manipulator subject to a second-order nonholonomic constraint.
Transparent Bilateral Teleoperation under Position and Rate Control
Authors: Salcudean Septimiu E. , Zhu Ming , Zhu Wen-Hong , Hashtrudi-Zaad Keyvan
Published: July 2003

A four-channel control architecture has been suggested in the literature to achieve transparency for master-slave teleoperator systems under position control. In this paper, the result is generalized to include teleoperator systems that are under rate control or more general master-slave kinematic correspondence laws, such as a mixedposition/rate mode. A one-degree-of-freedom example is given to outline the design and analysis of such a system for transparency and stability. The validity of the theory has been verified through simulations and experiments.
Experimental Validation of Contact Dynamics Simulation of Constrained Robotic Tasks
Authors: Van Vliet J. , Sharf I. , Ma O.
Published: July 2003

Dynamics simulation plays a key role in the design, verification, and operation planning of space manipulator systems because of the difficulties of ground-based physical tests with large, flexible robotic systems. Modeling of contact dynamics has increasingly become an essential step in dynamics simulation of space station robotic operations (such as the assembly and maintenance of the station). This role requires the modeling tool to have very high fidelity. This paper describes a research project aimed at experimentally validating a general contact dynamics simulation software developed by McDonald Dettwiler Space and Advanced Robotics Ltd (previously Spar Aerospace Ltd). The experimental tests were carried out in the robotics laboratory at the University of Victoria. The validation results demonstrated that the software is capable of predicting realistic contact behavior.
A Nested-Loop Architecture for Mobile Robot Navigation
Authors: Santos Vitor M. , Castro José P. , Ribeiro M. Isabel
Published: July 2003

This paper describes a navigation architecture for mobile robots, structured as a set of nested control loops whose depth is related to their knowledge of the environment and the ability to drive the actuator, and involving as well competing behaviors that will ultimately generate the robot motion. The architecture has been successfully used on a mobile platform to support three-dimensional environment reconstruction tasks. The architecture may be classified as belonging to the hybrid type but made up of hybrid elements as well, allowing virtually any level of input awareness and ranging from high-level task planning to direct motion commands issued by external user or applications. A monitorized data path ensures the construction of the most adequate and safe motion, as well as an unlimited set of behaviors depending on the already known and perceived environment. Added concepts of path recovering and assisted navigation fulfill the demands for the three-dimensional acquisition scheme involved. Some comparison with existing architectures is carried out throughout the text. The versatility and robustness of the architecture are supported by extensive results.
Real-Time Solution of the Inverse Kinematic-Rate Problem
Authors: Lucas Stuart R. , Tischler Craig R. , Samuel Andrew E.
Published: July 2003

Solving the inverse kinematic-rate problem is an old and ever-present problem in robotics. Many methods of solution for this problem have been discussed over the past 30 years and, as computational speeds have improved, there has been greater expectation that this calculation will be performed online. This paper compares the merits of many of the methods already presented and describes a new approach that leads to a fast and numerically well-conditioned algorithm. This method is most advantageous for robots with a spherical wrist, which is a common feature among industrial robots. More important, we uncover some interesting properties of efficient solutions that can be applied to a variety of robot architectures. We apply this and other methods to an industrial robot with near to PUMA geometry and report calculation speeds indicative of the real-time cost of each of the several procedures.
Range-Sensor-Based Navigation in Three-Dimensional Polyhedral Environments
Authors: Kamon Ishay , Rimon Elon , Rivlin Ehud
Published: July 2003

This paper is concerned with the problem of sensor-based navigation in three dimensions. The robot, which is modeled as a “bug” or a “point robot,” has no a priori knowledge of the environment. It must rather use its sensors to perceive the environment and plan a collision-free path to various targets. The robot is further required to navigate in the most reactive way possible, retaining the smallest amount of information required for global convergence to the target. We assume a three-dimensional polyhedral environment and present two basic results for sensor-based navigation in this environment. First we establish sufficient conditions for range-sensor-based exploration of the entire surface of a general polyhedron and present a strategy for performing this task. Then we characterize the locally shortest path from the current robot location to the target and present a method for estimating this path in time that is linear with the problem size. Based on these results, we present a range-sensor-based navigation algorithm for a bug robot in a general three-dimensional polyhedral environment. The algorithm, called 3 DBug, strives to process the sensory data in the most reactive way possible, without sacrificing its global convergence guarantee. The algorithm uses two modes of motion, called motion-toward-the-target and obstacle- surface-traversal. During the first mode of motion, the robot follows the locally shortest path to the target in a purely reactive fashion. During the second mode of motion, the robot attempts to reach exit points along an obstacle surface, while simultaneously expanding its knowledge of the obstacle based on range data. We provide analysis of the algorithm, showing that if the target is reachable, the robot always finds obstacle exit points from which it reaches the target. Otherwise, the robot eventually possesses full knowledge of the obstacle blocking its path to the target and determines that the target is unreachable. We have also implemented and verified the algorithm on three-dimensional simulated environments. The simulation results show that 3 DBug generates paths that resemble the globally shortest path in simple scenarios and reasonably short paths in concave roomlike environments.